@article {2015A\&A...574A..65B, title = {{Molecular gas and nuclear activity in early-type galaxies: any link with radio loudness?}}, journal = {Astronomy and Astrophysics}, volume = {574}, year = {2015}, month = {feb}, pages = {A65}, abstract = {
Aims: We want to study the amount of molecular gas in a sample of nearby early-type galaxies (ETGs) that host low-luminosity active galactic nuclei (AGN). We look for possible differences between the radio-loud (RL) and radio-quiet (RQ) AGN.
Methods: We observed the CO(1-0) and CO(2-1) spectral lines with the IRAM 30 m and NRO 45 m telescopes for eight galaxies. They belong to a large sample of 37 local ETGs that host both RQ and RL AGN. We gather data from the literature for the entire sample.
Results: We report the new detection of CO(1-0) emission in four galaxies (UGC 0968, UGC 5617, UGC 6946, and UGC 8355) and CO(2-1) emission in two of them (UGC 0968 and UGC 5617). The CO(2-1)/CO(1-0) ratio in these sources is \~{} 0.7 {\plusmn} 0.2. Considering both the new observations and the literature, the detection rate of CO in our sample is 55{\plusmn} 9\%, with no statistically significant difference between the hosts of RL and RQ AGNs. For all the detected galaxies we converted the CO luminosities into the molecular masses, M$_{H2}$, which range from 10$^{6.5}$ to 10$^{8.5}$ M$_{\&sun;}$, without any statistically significant differences between RL and RQ galaxies. This suggests that the amount of molecular gas does not likely set the radio loudness of the AGN. Furthermore, despite the low statistical significance, the presence of a weak trend between the H$_{2}$ mass with various tracers of nuclear activity (mainly [O III] emission line nuclear power) cannot be excluded. Based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).}, keywords = {cD, galaxies: active, galaxies: elliptical and lenticular, galaxies: ISM, galaxies: nuclei, ISM: molecules}, doi = {10.1051/0004-6361/201425131}, url = {http://adsabs.harvard.edu/abs/2015A\%26A...574A..65B}, author = {Baldi, R.~D. and Giroletti, M. and Capetti, A. and Giovannini, G. and Casasola, V. and M. A. P{\'e}rez-Torres and Kuno, N.} } @article {231, title = {{Multiple AGN in the crowded field of the compact group SDSS J0959+1259}}, journal = {MNRAS}, volume = {453}, year = {2015}, pages = {214-221}, keywords = {galaxies: active, galaxies: interactions, galaxies: Seyfert, X-rays: galaxies}, doi = {10.1093/mnras/stv1623}, url = {http://adsabs.harvard.edu/abs/2015MNRAS.453..214D}, author = {De Rosa, A. and Bianchi, S. and Bogdanovi{\'c}, T. and Decarli, R. and Herrero-Illana, R. and Husemann, B. and Komossa, S. and Kun, E. and Loiseau, N. and Paragi, Z. and P{\'e}rez-Torres, M. and Piconcelli, E. and Schawinski, K. and Vignali, C.} } @article {2014A\&A...565A..19R, title = {{The molecular gas content of ULIRG type 2 quasars at z {\l}t} 1}}, journal = {Astronomy and Astrophysics}, volume = {565}, year = {2014}, month = {may}, pages = {A19}, abstract = {We present new results of CO(1-0) spectroscopic observations of four Sloan Digital Sky Survey (SDSS) type 2 quasars (QSO2) at z \~{} 0.3, observed with the 30-m IRAM radio telescope. The QSO2 have infrared luminosities in the ultra-luminous infrared galaxies (ULIRG) regime. We confirm the CO(1-0) detection in one of our four QSO2, SDSS J1543-00, with L{\textquoteright}$_{CO}$ and M$_{H2}$ (1.2 {\plusmn} 0.2) {\times} 10$^{10}$ K km s$^{-1}$ pc$^{2}$ and (9.4 {\plusmn} 1.4) {\times} 10$^{9}$ M $_{\&sun;}$, respectively. The full width at half maximum (FWHM) of the CO(1-0) line is =575 {\plusmn} 102 km s$^{-1}$. No CO(1-0) emission is detected in SDSS J0903+02, SDSS J1337-01, SDSS J1520-01 above 3 sigma, yielding upper limits on M(H$_{2}$) \~{} 9.6, 4.3 and 5.1 {\times} 10$^{9}$ M$_{\&sun;}$, respectively. We expand previous studies of the molecular gas content of intermediate z QSO2 into the ULIRG regime. Taking into account nine QSO2 at z \~{} 0.3-1.0 from the literature, we discuss the location of the 13 ULIRG QSO2 at z {\l}t} 1 with available L{\textquoteright}$_{CO}$ measurements in the L{\textquoteright}$_{CO}$ vs. z and L{\textquoteright}$_{CO}$ vs. L$_{FIR}$ diagrams, in comparison with other QSO1 and ULIRG star forming samples. Based on observations carried out with the IRAM 30 m radiotelescope.}, keywords = {galaxies: ISM, quasars: emission lines, quasars: general}, doi = {10.1051/0004-6361/201323004}, url = {http://adsabs.harvard.edu/abs/2014A\%26A...565A..19R}, author = {M. Rodr{\'\i}guez and Villar-Mart{\'\i}n, M. and Emonts, B. and Humphrey, A. and Drouart, G. and S. Garc{\'\i}a-Burillo and P{\'e}rez Torres, M.} } @article {220, title = {{The molecular gas reservoir of 6 low-metallicity galaxies from the Herschel Dwarf Galaxy Survey. A ground-based follow-up survey of CO(1-0), CO(2-1), and CO(3-2)}}, journal = {\aap}, volume = {564}, year = {2014}, pages = {A121}, keywords = {galaxies: dwarf, galaxies: ISM, infrared: galaxies, ISM: molecules, radio lines: galaxies}, doi = {10.1051/0004-6361/201322096}, author = {Cormier, D. and Madden, S.~C. and Lebouteiller, V. and Hony, S. and Aalto, S. and Costagliola, F. and Hughes, A. and R{\'e}my-Ruyer, A. and Abel, N. and Bayet, E. and Bigiel, F. and Cannon, J.~M. and Cumming, R.~J. and Galametz, M. and Galliano, F. and Viti, S. and Wu, R.} } @article {2014A\&A...564A.121C, title = {{The molecular gas reservoir of 6 low-metallicity galaxies from the Herschel Dwarf Galaxy Survey. A ground-based follow-up survey of CO(1-0), CO(2-1), and CO(3-2)}}, journal = {Astronomy and Astrophysics}, volume = {564}, year = {2014}, month = {apr}, pages = {A121}, abstract = {Context. Observations of nearby starburst and spiral galaxies have revealed that molecular gas is the driver of star formation. However, some nearby low-metallicity dwarf galaxies are actively forming stars, but CO, the most common tracer of this reservoir, is faint, leaving us with a puzzle about how star formation proceeds in these environments.
Aims: We aim to quantify the molecular gas reservoir in a subset of 6 galaxies from the Herschel Dwarf Galaxy Survey with newly acquired CO data and to link this reservoir to the observed star formation activity.
Methods: We present CO(1-0), CO(2-1), and CO(3-2) observations obtained at the ATNF Mopra 22-m, APEX, and IRAM 30-m telescopes, as well as [C ii] 157{$μ$}m and [O i] 63{$μ$}m observations obtained with the Herschel/PACS spectrometer in the 6 low-metallicity dwarf galaxies: Haro 11, Mrk 1089, Mrk 930, NGC 4861, NGC 625, and UM 311. We derived their molecular gas masses from several methods, including using the CO-to-H$_{2}$ conversion factor X$_{CO}$ (both Galactic and metallicity-scaled values) and dust measurements. The molecular and atomic gas reservoirs were compared to the star formation activity. We also constrained the physical conditions of the molecular clouds using the non-LTE code RADEX and the spectral synthesis code Cloudy.
Results: We detect CO in 5 of the 6 galaxies, including first detections in Haro 11 (Z \~{} 0.4 Z$_{\&sun;}$), Mrk 930 (0.2 Z$_{\&sun;}$), and UM 311 (0.5 Z$_{\&sun;}$), but CO remains undetected in NGC 4861 (0.2 Z$_{\&sun;}$). The CO luminosities are low, while [C ii] is bright in these galaxies, resulting in [C ii]/CO(1-0) {\ge} 10 000. Our dwarf galaxies are in relatively good agreement with the Schmidt-Kennicutt relation for total gas. They show short molecular depletion timescales, even when considering metallicity-scaled X$_{CO}$ factors. Those galaxies are dominated by their H i gas, except Haro 11, which has high star formation efficiency and is dominated by ionized and molecular gas. We determine the mass of each ISM phase in Haro 11 using Cloudy and estimate an equivalent X$_{CO}$ factor that is 10 times higher than the Galactic value. Overall, our results confirm the emerging picture that CO suffers from significant selective photodissociation in low-metallicity dwarf galaxies.}, keywords = {galaxies: dwarf, galaxies: ISM, infrared: galaxies, ISM: molecules, radio lines: galaxies}, doi = {10.1051/0004-6361/201322096}, url = {http://adsabs.harvard.edu/abs/2014A\%26A...564A.121C}, author = {Cormier, D. and Madden, S.~C. and Lebouteiller, V. and Hony, S. and Aalto, S. and F. Costagliola and Hughes, A. and R{\'e}my-Ruyer, A. and Abel, N. and Bayet, E. and Bigiel, F. and Cannon, J.~M. and Cumming, R.~J. and Galametz, M. and Galliano, F. and Viti, S. and Wu, R.} } @article {2014A\&A...567A.125G, title = {{Molecular line emission in NGC 1068 imaged with ALMA. I. An AGN-driven outflow in the dense molecular gas}}, journal = {Astronomy and Astrophysics}, volume = {567}, year = {2014}, month = {jul}, pages = {A125}, abstract = {
Aims: We investigate the fueling and the feedback of star formation and nuclear activity in NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy, by analyzing the distribution and kinematics of the molecular gas in the disk. We aim to understand if and how gas accretion can self-regulate.
Methods: We have used the Atacama Large Millimeter Array (ALMA) to map the emission of a set of dense molecular gas (n(H$_{2}$) {\sime} 10$^{5 - 6}$ cm$^{-3}$) tracers (CO(3-2), CO(6-5), HCN(4-3), HCO$^{+}$(4-3), and CS(7-6)) and their underlying continuum emission in the central r \~{} 2 kpc of NGC 1068 with spatial resolutions \~{}0.3{\Prime} - 0.5{\Prime} (\~{}20-35 pc for the assumed distance of D = 14 Mpc).
Results: The sensitivity and spatial resolution of ALMA give an unprecedented detailed view of the distribution and kinematics of the dense molecular gas (n(H$_{2}$) {\ge} 10$^{5 - 6}$cm$^{-3}$) in NGC 1068. Molecular line and dust continuum emissions are detected from a r \~{} 200 pc off-centered circumnuclear disk (CND), from the 2.6 kpc-diameter bar region, and from the r \~{} 1.3 kpc starburst (SB) ring. Most of the emission in HCO$^{+}$, HCN, and CS stems from the CND. Molecular line ratios show dramatic order-of-magnitude changes inside the CND that are correlated with the UV/X-ray illumination by the active galactic nucleus (AGN), betraying ongoing feedback. We used the dust continuum fluxes measured by ALMA together with NIR/MIR data to constrain the properties of the putative torus using CLUMPY models and found a torus radius of 20$^{+6}$$_{-10}$pc. The Fourier decomposition of the gas velocity field indicates that rotation is perturbed by an inward radial flow in the SB ring and the bar region. However, the gas kinematics from r \~{} 50 pc out to r \~{} 400 pc reveal a massive (M$_{mol}$\~{} 2.7$^{+0.9}$$_{-1.2}$ {\times} 10$^{7}$ M$_{\&sun;}$) outflow in all molecular tracers. The tight correlation between the ionized gas outflow, the radio jet, and the occurrence of outward motions in the disk suggests that the outflow is AGN driven.
Conclusions: The molecular outflow is likely launched when the ionization cone of the narrow line region sweeps the nuclear disk. The outflow rate estimated in the CND, dM/dt\~{} 63$^{+21}$$_{-37}$ M$_{\&sun;}$ yr$^{-1}$, is an order of magnitude higher than the star formation rate at these radii, confirming that the outflow is AGN driven. The power of the AGN is able to account for the estimated momentum and kinetic luminosity of the outflow. The CND mass load rate of the CND outflow implies a very short gas depletion timescale of {\l}e}1 Myr. The CND gas reservoir is likely replenished on longer timescales by efficient gas inflow from the outer disk. Based on observations carried out with ALMA in Cycle 0.}, keywords = {galaxies: individual: NGC 1068, galaxies: ISM, galaxies: kinematics and dynamics, galaxies: nuclei, galaxies: Seyfert, radio lines: galaxies}, doi = {10.1051/0004-6361/201423843}, url = {http://adsabs.harvard.edu/abs/2014A\%26A...567A.125G}, author = {S. Garc{\'\i}a-Burillo and Combes, F. and Usero, A. and Aalto, S. and Krips, M. and Viti, S. and Alonso-Herrero, A. and Hunt, L.~K. and Schinnerer, E. and Baker, A.~J. and Boone, F. and Casasola, V. and Colina, L. and F. Costagliola and Eckart, A. and Fuente, A. and Henkel, C. and Labiano, A. and Mart{\'\i}n, S. and Marquez, I. and Muller, S. and Planesas, P. and Ramos Almeida, C. and Spaans, M. and Tacconi, L.~J. and van der Werf, P.~P.} } @article {218, title = {{Molecular line emission in NGC 1068 imaged with ALMA. I. An AGN-driven outflow in the dense molecular gas}}, journal = {\aap}, volume = {567}, year = {2014}, pages = {A125}, keywords = {galaxies: individual: NGC 1068, galaxies: ISM, galaxies: kinematics and dynamics, galaxies: nuclei, galaxies: Seyfert, radio lines: galaxies}, doi = {10.1051/0004-6361/201423843}, author = {Garcia-Burillo, S. and Combes, F. and Usero, A. and Aalto, S. and Krips, M. and Viti, S. and Alonso-Herrero, A. and Hunt, L.~K. and Schinnerer, E. and Baker, A.~J. and Boone, F. and Casasola, V. and Colina, L. and Costagliola, F. and Eckart, A. and Fuente, A. and Henkel, C. and Labiano, A. and Mart{\'\i}n, S. and Marquez, I. and Muller, S. and Planesas, P. and Ramos Almeida, C. and Spaans, M. and Tacconi, L.~J. and van der Werf, P.~P.} } @article {2014A\&A...570A..28V, title = {{Molecular line emission in NGC 1068 imaged with ALMA. II. The chemistry of the dense molecular gas}}, journal = {Astronomy and Astrophysics}, volume = {570}, year = {2014}, month = {oct}, pages = {A28}, abstract = {
Aims: We present a detailed analysis of Atacama Large Millimeter/submillimeter Array (ALMA) Bands 7 and 9 data of CO, HCO$^{+}$, HCN, and CS, augmented with Plateau de Bure Interferometer (PdBI) data of the \~{}200 pc circumnuclear disc (CND) and the \~{}1.3 kpc starburst ring (SB ring) of NGC 1068, a nearby (D = 14 Mpc) Seyfert 2 barred galaxy. We aim to determine the physical characteristics of the dense gas present in the CND, and to establish whether the different line intensity ratios we find within the CND, as well as between the CND and the SB ring, are due to excitation effects (gas density and temperature differences) or to a different chemistry.
Methods: We estimate the column densities of each species in local thermodynamic equilibrium (LTE). We then compute large one-dimensional, non-LTE radiative transfer grids (using RADEX) by using only the CO transitions first, and then all the available molecules to constrain the densities, temperatures, and column densities within the CND. We finally present a preliminary set of chemical models to determine the origin of the gas.
Results: We find that, in general, the gas in the CND is very dense ({\gt}10$^{5}$ cm$^{-3}$) and hot (T{\gt} 150 K), with differences especially in the temperature across the CND. The AGN position has the lowest CO/HCO$^{+}$, CO/HCN, and CO/CS column density ratios. The RADEX analyses seem to indicate that there is chemical differentiation across the CND. We also find differences between the chemistry of the SB ring and some regions of the CND; the SB ring is also much colder and less dense than the CND. Chemical modelling does not succeed in reproducing all the molecular ratios with one model per region, suggesting the presence of multi-gas phase components.
Conclusions: The LTE, RADEX, and chemical analyses all indicate that more than one gas-phase component is necessary to uniquely fit all the available molecular ratios within the CND. A higher number of molecular transitions at the ALMA resolution is necessary to determine quantitatively the physical and chemical characteristics of these components. Tables 5-11 are available in electronic form at http://www.aanda.org}, keywords = {galaxies: active, galaxies: individual: NGC 1068, galaxies: ISM, galaxies: nuclei, molecular processes, radio lines: galaxies}, doi = {10.1051/0004-6361/201424116}, url = {http://adsabs.harvard.edu/abs/2014A\%26A...570A..28V}, author = {Viti, S. and S. Garc{\'\i}a-Burillo and Fuente, A. and Hunt, L.~K. and Usero, A. and Henkel, C. and Eckart, A. and Mart{\'\i}n, S. and Spaans, M. and Muller, S. and Combes, F. and Krips, M. and Schinnerer, E. and Casasola, V. and F. Costagliola and Marquez, I. and Planesas, P. and van der Werf, P.~P. and Aalto, S. and Baker, A.~J. and Boone, F. and Tacconi, L.~J.} } @article {217, title = {{Molecular line emission in NGC 1068 imaged with ALMA. II. The chemistry of the dense molecular gas}}, journal = {\aap}, volume = {570}, year = {2014}, pages = {A28}, keywords = {galaxies: active, galaxies: individual: NGC 1068, galaxies: ISM, galaxies: nuclei, molecular processes, radio lines: galaxies}, doi = {10.1051/0004-6361/201424116}, author = {Viti, S. and Garcia-Burillo, S. and Fuente, A. and Hunt, L.~K. and Usero, A. and Henkel, C. and Eckart, A. and Mart{\'\i}n, S. and Spaans, M. and Muller, S. and Combes, F. and Krips, M. and Schinnerer, E. and Casasola, V. and Costagliola, F. and Marquez, I. and Planesas, P. and van der Werf, P.~P. and Aalto, S. and Baker, A.~J. and Boone, F. and Tacconi, L.~J.} } @article {2014ApJ...786..156H, title = {{A Multi-wavelength View of the Central Kiloparsec Region in the Luminous Infrared Galaxy NGC 1614}}, journal = {The Astrophysical Journal}, volume = {786}, year = {2014}, month = {may}, pages = {156}, abstract = {The Luminous Infrared Galaxy NGC 1614 hosts a prominent circumnuclear ring of star formation. However, the nature of the dominant emitting mechanism in its central \~{}100 pc is still under debate. We present sub-arcsecond angular resolution radio, mid-infrared, Pa{$\alpha$}, optical, and X-ray observations of NGC 1614, aimed at studying in detail both the circumnuclear ring and the nuclear region. The 8.4 GHz continuum emission traced by the Very Large Array and the Gemini/T-ReCS 8.7 {$μ$}m emission, as well as the Pa{$\alpha$} line emission, show remarkable morphological similarities within the star-forming ring, suggesting that the underlying emission mechanisms are tightly related. We used a Hubble Space Telescope/NICMOS Pa{$\alpha$} map of similar resolution to our radio maps to disentangle the thermal free-free and non-thermal synchrotron radio emission, from which we obtained the intrinsic synchrotron power law for each individual region within the central kiloparsec of NGC 1614. The radio ring surrounds a relatively faint, steep-spectrum source at the very center of the galaxy, suggesting that the central source is not powered by an active galactic nucleus (AGN), but rather by a compact (r {\l}t}\~{} 90 pc) starburst (SB). Chandra X-ray data also show that the central kiloparsec region is dominated by SB activity, without requiring the existence of an AGN. We also used publicly available infrared data to model-fit the spectral energy distribution of both the SB ring and a putative AGN in NGC 1614. In summary, we conclude that there is no need to invoke an AGN to explain the observed bolometric properties of the galaxy.}, keywords = {galaxies: individual: NGC 1614, galaxies: nuclei, galaxies: starburst, infrared: galaxies, radio continuum: galaxies, supernovae: general}, doi = {10.1088/0004-637X/786/2/156}, url = {http://adsabs.harvard.edu/abs/2014ApJ...786..156H}, author = {R. Herrero-Illana and M. A. P{\'e}rez-Torres and Alonso-Herrero, A. and Alberdi, A. and Colina, L. and Efstathiou, A. and Hern{\'a}ndez-Garc{\'\i}a, L. and Miralles-Caballero, D. and V{\"a}is{\"a}nen, P. and Packham, C.~C. and Rajpaul, V. and Zijlstra, A.~A.} } @article {2013MNRAS.434..978V, title = {{Molecular gas in type 2 quasars at z {\tilde} 0.2-0.3}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {434}, year = {2013}, month = {sep}, pages = {978-991}, abstract = {{We present results of CO(1-0) spectroscopic observations of 10 Sloan Digital Sky Survey type 2 quasars (QSO2) at z {\tilde} 0.2-0.3 observed with the 30-m IRAM radio telescope and the Australia Telescope Compact Array. We report five new confirmed CO(1-0) detections and one tentative detection. They have L\^{}{\textquoteright} $\}$\_CO {\tilde} several {\times} 10$^{9}$ K km s$^{-1}$ pc$^{2}$, while upper limits for the non-detections are L\^{}{\textquoteright} $\}, keywords = {galaxies: evolution, galaxies: interactions, quasars: general}, author = {Villar-Mart{\'\i}n, M. and M. Rodr{\'\i}guez and Drouart, G. and Emonts, B. and Colina, L. and Humphrey, A. and S. Garc{\'\i}a-Burillo and Graci{\'a} Carpio, J. and Planesas, P. and P{\'e}rez Torres, M. and Arribas, S.} } @article {2012A\&A...544A..96A, title = {{MAGIC observations of the giant radio galaxy M 87 in a low-emission state between 2005 and 2007}}, journal = {Astronomy and Astrophysics}, volume = {544}, year = {2012}, month = {aug}, pages = {A96}, abstract = {Context. We present the results of a long M 87 monitoring campaign in very high energy {$\gamma$}-rays with the MAGIC-I Cherenkov telescope.
Aims: We aim to model the persistent non-thermal jet emission by monitoring and characterizing the very high energy {$\gamma$}-ray emission of M 87 during a low state.
Methods: A total of 150 h of data were taken between 2005 and 2007 with the single MAGIC-I telescope, out of which 128.6 h survived the data quality selection. We also collected data in the X-ray and Fermi-LAT bands from the literature (partially contemporaneous).
Results: No flaring activity was found during the campaign. The source was found to be in a persistent low-emission state, which was at a confidence level of 7{$\sigma$}. We present the spectrum between 100 GeV and 2 TeV, which is consistent with a simple power law with a photon index {$\Gamma$} = 2.21 {\plusmn} 0.21 and a flux normalization at 300 GeV of (7.7 {\plusmn} 1.3) {\times} 10$^{-8}$ TeV$^{-1}$ s$^{-1}$ m$^{-2}$. The extrapolation of the MAGIC spectrum into the GeV energy range matches the previously published Fermi-LAT spectrum well, covering a combined energy range of four orders of magnitude with the same spectral index. We model the broad band energy spectrum with a spine layer model, which can satisfactorily describe our data.}, keywords = {galaxies: individual: M 87, gamma rays: galaxies}, doi = {10.1051/0004-6361/201117827}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...544A..96A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Gaug, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and Ghisellini, G.} } @article {2012A\&A...541A..13A, title = {{Morphological and spectral properties of the W51 region measured with the MAGIC telescopes}}, journal = {Astronomy and Astrophysics}, volume = {541}, year = {2012}, month = {may}, pages = {A13}, abstract = {Context. The W51 complex hosts the supernova remnant W51C which is known to interact with the molecular clouds in the star forming region W51B. In addition, a possible pulsar wind nebula CXO J192318.5+140305 was found likely associated with the supernova remnant. Gamma-ray emission from this region was discovered by Fermi/LAT (between 0.2 and 50 GeV) and H.E.S.S. ({\gt}1 TeV). The spatial distribution of the events could not be used to pinpoint the location of the emission among the pulsar wind nebula, the supernova remnant shell and/or the molecular cloud. However, the modeling of the spectral energy distribution presented by the Fermi/LAT collaboration suggests a hadronic emission mechanism. The possibility that the gamma-ray emission from such an object is of hadronic origin can contribute to solvingthe long-standing problem of the contribution to galactic cosmic rays by supernova remnants.
Aims: Our aim is to determine the morphology of the very-high-energy gamma-ray emission of W51 and measure its spectral properties.
Methods: We performed observations of the W51 complex with the MAGIC telescopes for more than 50 h. The energy range accessible with MAGIC extends from 50 GeV to several TeV, allowing for the first spectral measurement at these energies. In addition, the good angular resolution in the medium (few hundred GeV) to high (above 1 TeV) energies allow us to perform morphological studies. We look for underlying structures by means of detailed morphological studies. Multi-wavelength data from this source have been sampled to model the emission with both leptonic and hadronic processes.
Results: We detect an extended emission of very-high-energy gamma rays, with a significance of 11 standard deviations. We extend the spectrum from the highest Fermi/LAT energies to \~{}5 TeV and find that it follows a single power law with an index of 2.58 {\plusmn} 0.07$_{stat}$ {\plusmn} 0.22$_{syst}$. The main part of the emission coincides with the shocked cloud region, while we find a feature extending towards the pulsar wind nebula. The possible contribution of the pulsar wind nebula, assuming a point-like source, shows no dependence on energy and it is about 20\% of the overall emission. The broad band spectral energy distribution can be explained with a hadronic model that implies proton acceleration above 100 TeV. This result, together with the morphology of the source, tentatively suggests that we observe ongoing acceleration of ions in the interaction zone between supernova remnant and cloud.}, keywords = {acceleration of particles, gamma rays: general, gamma rays: ISM, ISM: clouds, ISM: supernova remnants}, doi = {10.1051/0004-6361/201218846}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...541A..13A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barres de Almeida, U. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Da Vela, P. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Eisenacher, D. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Gonz{\'a}lez Mu{\~n}oz, A. and Gozzini, S.~R. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jankowski, F. and Jogler, T. and Kadenius, V. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lewandowska, N. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and L{\'o}pez-Coto, R. and L{\'o}pez-Oramas, A. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Niedzwiecki, A. and Nieto, D. and Nilsson, K. and Nowak, N. and Orito, R. and Paiano, S. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and M. A. P{\'e}rez-Torres and Persic, M. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puerto Gimenez, I. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Snidaric, I. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamatescu, V. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Sun, S. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2012A\&A...542A.100A, title = {{Mrk 421 active state in 2008: the MAGIC view, simultaneous multi-wavelength observations and SSC model constrained}}, journal = {Astronomy and Astrophysics}, volume = {542}, year = {2012}, month = {jun}, pages = {A100}, abstract = {Context. The blazar Markarian 421 is one of the brightest TeV gamma-ray sources of the northern sky. From December 2007 until June 2008 it was intensively observed in the very high energy (VHE, E {\gt} 100 GeV) band by the single-dish Major Atmospheric Gamma-ray Imaging Cherenkov telescope (MAGIC-I).
Aims: We aimed to measure the physical parameters of the emitting region of the blazar jet during active states.
Methods: We performed a dense monitoring of the source in VHE with MAGIC-I, and also collected complementary data in soft X-rays and optical-UV bands; then, we modeled the spectral energy distributions (SED) derived from simultaneous multi-wavelength data within the synchrotron self-Compton (SSC) framework.
Results: The source showed intense and prolonged {$\gamma$}-ray activity during the whole period, with integral fluxes (E {\gt} 200 GeV) seldom below the level of the Crab Nebula, and up to 3.6 times this value. Eight datasets of simultaneous optical-UV (KVA, Swift/UVOT), soft X-ray (Swift/XRT) and MAGIC-I VHE data were obtained during different outburst phases. The data constrain the physical parameters of the jet, once the spectral energy distributions obtained are interpreted within the framework of a single-zone SSC leptonic model.
Conclusions: The main outcome of the study is that within the homogeneous model high Doppler factors (40 {\l}e} {$δ$} {\l}e} 80) are needed to reproduce the observed SED; but this model cannot explain the observed short time-scale variability, while it can be argued that inhomogeneous models could allow for less extreme Doppler factors, more intense magnetic fields and shorter electron cooling times compatible with hour or sub-hour scale variability.}, keywords = {BL Lacertae objects: individual: Mrk 421, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/201117442}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...542A.100A}, author = {Aleksi{\'c}, J. and Alvarez, E.~A. and Antonelli, L.~A. and Antoranz, P. and Asensio, M. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Caneva, G. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Kellermann, H. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, A. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Munar-Adrover, P. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Takami, H. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Uellenbeck, M. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011ApJ...730L...8A, title = {{MAGIC Discovery of Very High Energy Emission from the FSRQ PKS 1222+21}}, journal = {The Astrophysical Journal Letters}, volume = {730}, year = {2011}, month = {mar}, pages = {L8}, abstract = {{Very high energy (VHE) {$\gamma$}-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35}, keywords = {cosmic background radiation, galaxies: active, galaxies: jets, gamma rays: galaxies, quasars: individual: PKS 1222+21}, doi = {10.1088/2041-8205/730/1/L8}, url = {http://adsabs.harvard.edu/abs/2011ApJ...730L...8A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paneque, D. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration and Tanaka, Y.~T. and Wood, D.~L. and Buson, S.} } @article {2011A\&A...530A...4A, title = {{MAGIC Observations and multiwavelength properties of the quasar 3C 279 in 2007 and 2009}}, journal = {Astronomy and Astrophysics}, volume = {530}, year = {2011}, month = {jun}, pages = {A4}, abstract = {Context. 3C 279, the first quasar discovered to emit VHE {$\gamma$}-rays by the MAGIC telescope in 2006, was reobserved by MAGIC in January 2007 during a major optical flare and from December 2008 to April 2009 following an alert from the Fermi space telescope on an exceptionally high {$\gamma$}-ray state.
Aims: The January 2007 observations resulted in a detection on January 16 with significance 5.4{$\sigma$}, corresponding to a F ({\gt}150 GeV) (3.8 {\plusmn} 0.8) {\times} 10$^{-11}$ ph cm$^{-2}$ s$^{-1}$ while the overall data sample does not show significant signal. The December 2008-April 2009 observations did not detect the source. We study the multiwavelength behaviour of the source at the epochs of MAGIC observations, collecting quasi-simultaneous data at optical and X-ray frequencies and for 2009 also {$\gamma$}-ray data from Fermi.
Methods: We study the light curves and spectral energy distribution of the source. The spectral energy distributions of three observing epochs (including the February 2006, which has been previously published) are modelled with one-zone inverse Compton models and the emission on January 16, 2007 also with two zone model and with a lepto-hadronic model.
Results: We find that the VHE {$\gamma$}-ray emission detected in 2006 and 2007 challenges standard one-zone model, based on relativistic electrons in a jet scattering broad line region photons, while the other studied models fit the observed spectral energy distribution more satisfactorily.}, keywords = {gamma rays: galaxies, quasars: individual: 3C 279}, doi = {10.1051/0004-6361/201116497}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...530A...4A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Borla Tridon, D. and Braun, I. and Bretz, T. and Ca{\~n}ellas, A. and Carmona, E. and Carosi, A. and Colin, P. and Colombo, E. and Contreras, J.~L. and Cortina, J. and Cossio, L. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Fruck, C. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Garrido, D. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and H{\"a}fner, D. and Herrero, A. and Hildebrand, D. and Hose, J. and Hrupec, D. and Huber, B. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Krause, J. and La Barbera, A. and Lelas, D. and Leonardo, E. and Lindfors, E. and Lombardi, S. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Makariev, M. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Pardo, S. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pilia, M. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and R{\"u}gamer, S. and R{\"u}ger, M. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Thom, M. and Tibolla, O. and Torres, D.~F. and Treves, A. and Vankov, H. and Vogler, P. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} } @article {2011A\&A...532A..83S, title = {{The mean infrared emission of Sagittarius A*}}, journal = {Astronomy and Astrophysics}, volume = {532}, year = {2011}, month = {aug}, pages = {A83}, abstract = {Context. The massive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*) is, in relative terms, the weakest accreting black hole accessible to observations. It has inspired the theoretical models of radiatively inefficient accretion. Unfortunately, our knowledge of the mean SED and source structure of Sgr A* is very limited owing to numerous observational difficulties. At the moment, the mean SED of Sgr A* is only known reliably in the radio to mm regimes.
Aims: The goal of this paper is to provide constraints on the mean emission from Sgr A* in the near-to-mid infrared.
Methods: Sensitive images of the surroundings of Sgr A* at 8.6 {$μ$}m, 4.8 {$μ$}m , and 3.8 {$μ$}m were produced by combining large quantities of imaging data. Images were produced for several observing epochs. Excellent imaging quality was reached in the MIR by using speckle imaging combined with holographic image reconstruction, a novel technique for this kind of data.
Results: No counterpart of Sgr A* is detected at 8.6 {$μ$}m. At this wavelength, Sgr A* is located atop a dust ridge, which considerably complicates the search for a potential point source. An observed 3{$\sigma$} upper limit of \~{}10 mJy is estimated for the emission of Sgr A* at 8.6 {$μ$}m, a tighter limit at this wavelength than in previous work. The de-reddened 3{$\sigma$} upper limit, including the uncertainty of the extinction correction, is \~{}84 mJy . Based on the available data, it is argued that, with currently available instruments, Sgr A* cannot be detected in the MIR, not even during flares. At 4.8 {$μ$}m and 3.8 {$μ$}m, on the other hand, Sgr A* is detected at all times, at least when considering timescales of a few up to 13 min. We derive well-defined time-averaged, de-reddened flux densities of 3.8 {\plusmn} 1.3 mJy at 4.8 {$μ$}m and 5.0 {\plusmn} 0.6 mJy at 3.8 {$μ$}m. Observations with NIRC2/Keck and NaCo/VLT from the literature provide good evidence that Sgr A* also has a fairly well-defined de-reddened mean flux of 0.5-2.5 mJy at wavelengths of 2.1-2.2 {$μ$}m.
Conclusions: We present well-constrained anchor points for the SED of Sgr A* on the high-frequency side of the Terahertz peak. The new data are in general agreement with published theoretical SEDs of the mean emission from Sgr A*, but we expect them to have an appreciable impact on the model parameters in future theoretical work.}, keywords = {black hole physics, Galaxy: center, instrumentation: adaptive optics, instrumentation: high angular resolution}, doi = {10.1051/0004-6361/201116994}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...532A..83S}, author = {Sch{\"o}del, R. and Morris, M.~R. and Muzi{\'c}, K. and Alberdi, A. and Meyer, L. and Eckart, A. and Gezari, D.~Y.} } @article {2011A\&A...531A..52M, title = {{A model for the thermal radio-continuum emission from radiative shocks in colliding stellar winds}}, journal = {Astronomy and Astrophysics}, volume = {531}, year = {2011}, month = {jul}, pages = {A52}, abstract = {Context. In massive-star binary systems, the interaction of the strong stellar winds results in a wind collision region (WCR) between the stars, which is limited by two shock fronts. Besides the nonthermal emission resulting from the shock acceleration, these shocks emit thermal (free-free) radiation detectable at radio frequencies that increase the expected emission from the stellar winds. Observations and theoretical studies of these sources show that the shocked gas is an important, but not dominant, contributor to the total emission in wide binary systems, while it plays a very substantial role in close binaries.
Aims: The interaction of two isotropic stellar winds is studied in order to calculate the free-free emission from the WCR. The effects of the binary separation and the wind momentum ratio on the emission from the wind-wind interaction region are investigated.
Methods: We developed a semi-analytical model for calculating the thermal emission from colliding stellar winds. Assuming radiative shocks for the compressed layer, which are expected in close binaries, we obtained the emission measure of the thin shell. Then, we computed the total optical depth along each line of sight to obtain the emission from the whole configuration.
Results: Here, we present predictions of the free-free emission at radio frequencies from analytic, radiative shock models in colliding wind binaries. It is shown that the emission from the WCR mainly arises from the optically thick region of the compressed layer and scales as \~{}D$^{4/5}$, where D is the binary separation. The predicted flux density S$_{nu}$ from the WCR becomes more important as the frequency {$ν$} increases, showing higher spectral indices than the expected 0.6 value (S$_{nu}$ {\prop} {$ν$}$^{alpha}$, where {$\alpha$} = 0.6) from the unshocked winds. We also investigate the emission from short-period WR+O systems calculated with our analytic formulation. In particular, we apply the model to the binary systems WR 98 and WR 113 and compare our results with the observations. Our theoretical results are in good agreement with the observed thermal spectra from these sources.}, keywords = {binaries: close, radiation mechanisms: thermal, radio continuum: stars, stars: Wolf-Rayet}, doi = {10.1051/0004-6361/201015988}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...531A..52M}, author = {Montes, G. and Gonz{\'a}lez, R.~F. and Cant{\'o}, J. and M. A. P{\'e}rez-Torres and Alberdi, A.} } @article {2011A\&A...528A..30C, title = {{Molecules as tracers of galaxy evolution: an EMIR survey. I. Presentation of the data and first results}}, journal = {Astronomy and Astrophysics}, volume = {528}, year = {2011}, month = {apr}, pages = {A30}, abstract = {
Aims: We investigate the molecular gas properties of a sample of 23 galaxies in order to find and test chemical signatures of galaxy evolution and to compare them to IR evolutionary tracers.
Methods: Observation at 3 mm wavelengths were obtained with the EMIR broadband receiver, mounted on the IRAM 30 m telescope on Pico Veleta, Spain. We compare the emission of the main molecular species with existing models of chemical evolution by means of line intensity ratios diagrams and principal component analysis.
Results: We detect molecular emission in 19 galaxies in two 8 GHz-wide bands centred at 88 and 112 GHz. The main detected molecules are CO, $^{13}$CO, HCN, HNC, HCO$^{+}$, CN, and C$_{2}$H. We also detect HC$_{3}$N J = 10-9 in the galaxies IRAS 17208, IC 860, NGC 4418, NGC 7771, and NGC 1068. The only HC$_{3}$N detections are in objects with HCO$^{+}$/HCN {\l}t} 1. Galaxies with the highest HC$_{3}$N/HCN ratios have warm IRAS colours (60/100 {$μ$}m {\gt} 0.8). The brightest HC$_{3}$N emission is found in IC 860, where we also detect the molecule in its vibrationally excited state. We find low HNC/HCN line ratios ({\l}t}0.5), that cannot be explained by existing PDR or XDR chemical models. The intensities of HCO+ and HNC appear anti-correlated. No correlation is found between the HNC/HCN line ratio and dust temperature. All HNC-bright objects are either luminous IR galaxies (LIRG) or Seyferts. Galaxies with bright polycyclic aromatic hydrocarbons (PAH) emission show low HNC/HCO$^{+}$ ratios. The CO/$^{13}$CO ratio is positively correlated with the dust temperature and is generally higher than in our galaxy. The emission of CN and C$^{18}$O is correlated.
Conclusions: Bright HC$_{3}$N emission in HCO$^{+}$-faint objects may imply that these are not dominated by X-ray chemistry. Thus the HCN/HCO$^{+}$ line ratio is not, by itself, a reliable tracer of XDRs. Bright HC$_{3}$N and faint HCO$^{+}$ could be signatures of embedded star-formation, instead of AGN activity. Mechanical heating caused by supernova explosions may be responsible for the low HNC/HCN and high HCO$^{+}$/HCN ratios in some starbursts. We cannot exclude, however, that the discussed trends are largely caused by optical depth effects or excitation. Chemical models alone cannot explain all properties of the observed molecular emission. Better constraints to the gas spacial distribution and excitation are needed to distinguish abundance and excitation effects. Appendices are only available in electronic form http://www.aanda.org}, keywords = {evolution, galaxies: active, galaxies: evolution, galaxies: ISM, ISM: molecules}, doi = {10.1051/0004-6361/201015628}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...528A..30C}, author = {F. Costagliola and Aalto, S. and M. Rodr{\'\i}guez and Muller, S. and Spoon, H.~W.~W. and Mart{\'\i}n, S. and M. A. P{\'e}rez-Torres and Alberdi, A. and Lindberg, J.~E. and Batejat, F. and J{\"u}tte, E. and van der Werf, P. and Lahuis, F.} } @article {2010ApJ...721..843A, title = {{Magic Constraints on {$\gamma$}-ray Emission from Cygnus X-3}}, journal = {The Astrophysical Journal}, volume = {721}, year = {2010}, month = {sep}, pages = {843-855}, abstract = {Cygnus X-3 is a microquasar consisting of an accreting compact object orbiting around a Wolf-Rayet star. It has been detected at radio frequencies and up to high-energy {$\gamma$} rays (above 100 MeV). However, many models also predict a very high energy (VHE) emission (above hundreds of GeV) when the source displays relativistic persistent jets or transient ejections. Therefore, detecting such emission would improve the understanding of the jet physics. The imaging atmospheric Cherenkov telescope MAGIC observed Cygnus X-3 for about 70 hr between 2006 March and 2009 August in different X-ray/radio spectral states and also during a period of enhanced {$\gamma$}-ray emission. MAGIC found no evidence for a VHE signal from the direction of the microquasar. An upper limit to the integral flux for energies higher than 250 GeV has been set to 2.2 {\times} 10$^{-12}$ photons cm$^{-2}$ s$^{-1}$ (95\% confidence level). This is the best limit so far to the VHE emission from this source. The non-detection of a VHE signal during the period of activity in the high-energy band sheds light on the location of the possible VHE radiation favoring the emission from the innermost region of the jets, where absorption is significant. The current and future generations of Cherenkov telescopes may detect a signal under precise spectral conditions.}, keywords = {acceleration of particles, binaries: general, gamma rays: general, methods: observational, X-rays: binaries}, doi = {10.1088/0004-637X/721/1/843}, url = {http://adsabs.harvard.edu/abs/2010ApJ...721..843A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and G{\"o}ebel, F. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paiano, S. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration} } @article {2010ApJ...710..634A, title = {{MAGIC Gamma-ray Telescope Observation of the Perseus Cluster of Galaxies: Implications for Cosmic Rays, Dark Matter, and NGC 1275}}, journal = {The Astrophysical Journal}, volume = {710}, year = {2010}, month = {feb}, pages = {634-647}, abstract = {The Perseus galaxy cluster was observed by the MAGIC Cherenkov telescope for a total effective time of 24.4 hr during 2008 November and December. The resulting upper limits on the {$\gamma$}-ray emission above 100 GeV are in the range of 4.6-7.5 {\times} 10$^{-12}$ cm$^{-2}$ s$^{-1}$ for spectral indices from -1.5 to -2.5, thereby constraining the emission produced by cosmic rays, dark matter annihilations, and the central radio galaxy NGC 1275. Results are compatible with cosmological cluster simulations for the cosmic-ray-induced {$\gamma$}-ray emission, constraining the average cosmic ray-to-thermal pressure to {\l}t}4\% for the cluster core region ({\l}t}8\% for the entire cluster). Using simplified assumptions adopted in earlier work (a power-law spectrum with an index of -2.1, constant cosmic ray-to-thermal pressure for the peripheral cluster regions while accounting for the adiabatic contraction during the cooling flow formation), we would limit the ratio of cosmic ray-to-thermal energy to E $_{CR}$/E $_{th}$ {\l}t} 3\%. Improving the sensitivity of this observation by a factor of about 7 will enable us to scrutinize the hadronic model for the Perseus radio mini-halo: a non-detection of {$\gamma$}-ray emission at this level implies cosmic ray fluxes that are too small to produce enough electrons through hadronic interactions with the ambient gas protons to explain the observed synchrotron emission. The upper limit also translates into a level of {$\gamma$}-ray emission from possible annihilations of the cluster dark matter (the dominant mass component) that is consistent with boost factors of \~{}10$^{4}$ for the typically expected dark matter annihilation-induced emission. Finally, the upper limits obtained for the {$\gamma$}-ray emission of the central radio galaxy NGC 1275 are consistent with the recent detection by the Fermi-LAT satellite. Due to the extremely large Doppler factors required for the jet, a one-zone synchrotron self-Compton model is implausible in this case. We reproduce the observed spectral energy density by using the structured jet (spine-layer) model which has previously been adopted to explain the high-energy emission of radio galaxies.}, keywords = {galaxies: clusters: individual: Perseus, gamma rays: general}, doi = {10.1088/0004-637X/710/1/634}, url = {http://adsabs.harvard.edu/abs/2010ApJ...710..634A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Galante, N. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paiano, S. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M.~A. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and Zapatero, J. and Pfrommer, C. and Pinzke, A. and En{\ss}lin, T.~A. and Inoue, S. and Ghisellini, G. and MAGIC Collaboration} } @article {2010A\&A...517A...5A, title = {{MAGIC observation of the GRB 080430 afterglow}}, journal = {Astronomy and Astrophysics}, volume = {517}, year = {2010}, month = {jul}, pages = {A5}, abstract = {Context. Gamma-ray bursts are cosmological sources emitting radiation from the gamma-rays to the radio band. Substantial observational efforts have been devoted to the study of gamma-ray bursts during the prompt phase, i.e. the initial burst of high-energy radiation, and during the long-lasting afterglows. In spite of many successes in interpreting these phenomena, there are still several open key questions about the fundamental emission processes, their energetics and the environment.
Aims: Independently of specific gamma-ray burst theoretical recipes, spectra in the GeV/TeV range are predicted to be remarkably simple, being satisfactorily modeled with power-laws, and therefore offer a very valuable tool to probe the extragalactic background light distribution. Furthermore, the simple detection of a component at very-high energies, i.e. at \~{}100 GeV, would solve the ambiguity about the importance of various possible emission processes, which provide barely distinguishable scenarios at lower energies.
Methods: We used the results of the MAGIC telescope observation of the moderate resdhift (z \~{} 0.76) GRB 080430 at energies above about 80 GeV, to evaluate the perspective for late-afterglow observations with ground based GeV/TeV telescopes.
Results: We obtained an upper limit of F$_{95\% CL}$ = 5.5 {\times} 10$^{-11}$ erg cm$^{-2}$ s$^{-1}$ for the very-high energy emission of GRB 080430, which cannot set further constraints on the theoretical scenarios proposed for this object also due to the difficulties in modeling the low-energy afterglow. Nonetheless, our observations show that Cherenkov telescopes have already reached the required sensitivity to detect the GeV/TeV emission of GRBs at moderate redshift (z {\l}sim} 0.8), provided the observations are carried out at early times, close to the onset of their afterglow phase.}, keywords = {gamma-ray burst: individual: GRB 080430, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/200913461}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...517A...5A}, author = {Aleksi{\'c}, J. and Anderhub, H. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Becker, J.~K. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fern{\'a}ndez, E. and Firpo, R. and Fonseca, M.~V. and Font, L. and Galante, N. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and G{\"o}ebel, F. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Turini, N. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and Zapatero, J. and de Ugarte-Postigo, A. and MAGIC Collaboration} } @article {2010A\&A...519A..32A, title = {{MAGIC TeV gamma-ray observations of Markarian 421 during multiwavelength campaigns in 2006}}, journal = {Astronomy and Astrophysics}, volume = {519}, year = {2010}, month = {sep}, pages = {A32}, abstract = {Context. Wide-range spectral coverage of blazar-type active galactic nuclei is of paramount importance for understanding the particle acceleration mechanisms assumed to take place in their jets. The Major Atmospheric Gamma Imaging Cerenkov (MAGIC) telescope participated in three multiwavelength (MWL) campaigns, observing the blazar Markarian (Mkn) 421 during the nights of April 28 and 29, 2006, and June 14, 2006.
Aims: We analyzed the corresponding MAGIC very-high energy observations during 9 nights from April 22 to 30, 2006 and on June 14, 2006. We inferred light curves with sub-day resolution and night-by-night energy spectra.
Methods: MAGIC detects {$\gamma$}-rays by observing extended air showers in the atmosphere. The obtained air-shower images were analyzed using the standard MAGIC analysis chain.
Results: A strong {$\gamma$}-ray signal was detected from Mkn 421 on all observation nights. The flux (E {\gt} 250 GeV) varied on night-by-night basis between (0.92{\plusmn}0.11) {\times} 10$^{-10}$ cm$^{-2}$ s$^{-1}$ (0.57 Crab units) and (3.21{\plusmn}0.15) {\times} 10$^{-10}$ cm$^{-2}$ s$^{-1}$ (2.0 Crab units) in April 2006. There is a clear indication for intra-night variability with a doubling time of 36{\plusmn}10\_stat min on the night of April 29, 2006, establishing once more rapid flux variability for this object. For all individual nights {$\gamma$}-ray spectra could be inferred, with power-law indices ranging from 1.66 to 2.47. We did not find statistically significant correlations between the spectral index and the flux state for individual nights. During the June 2006 campaign, a flux substantially lower than the one measured by the Whipple 10-m telescope four days later was found. Using a log-parabolic power law fit we deduced for some data sets the location of the spectral peak in the very-high energy regime. Our results confirm the indications of rising peak energy with increasing flux, as expected in leptonic acceleration models.}, keywords = {BL Lacertae objects: individual: Mkn 421, gamma rays: galaxies, radiation mechanisms: non-thermal}, doi = {10.1051/0004-6361/200913945}, url = {http://adsabs.harvard.edu/abs/2010A\%26A...519A..32A}, author = {Aleksi{\'c}, J. and Anderhub, H. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Baixeras, C. and Balestra, S. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Becker, J.~K. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Bock, R.~K. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Britzger, D. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Commichau, S. and Contreras, J.~L. and Cortina, J. and Costado, M.~T. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and de los Reyes, R. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Hsu, C.~C. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and La Barbera, A. and Laille, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moles, M. and Moralejo, A. and Nieto, D. and Nilsson, K. and Ninkovic, J. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pascoli, D. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Prada, F. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schweizer, T. and Shayduk, M. and Shore, S.~N. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Zabalza, V. and Zandanel, F. and Zanin, R. and MAGIC Collaboration} } @article {2010ApJ...725.1629A, title = {{MAGIC Upper Limits for Two Milagro-detected Bright Fermi Sources in the Region of SNR G65.1+0.6}}, journal = {The Astrophysical Journal}, volume = {725}, year = {2010}, month = {dec}, pages = {1629-1632}, abstract = {We report on the observation of the region around supernova remnant G65.1+0.6 with the stand-alone MAGIC-I telescope. This region hosts the two bright GeV gamma-ray sources 1FGL J1954.3+2836 and 1FGL J1958.6+2845. They are identified as GeV pulsars and both have a possible counterpart detected at about 35 TeV by the Milagro observatory. MAGIC collected 25.5 hr of good quality data and found no significant emission in the range around 1 TeV. We therefore report differential flux upper limits, assuming the emission to be point-like ({\l}t}=0fdg1) or within a radius of 0fdg3. In the point-like scenario, the flux limits around 1 TeV are at the level of 3\% and 2\% of the Crab Nebula flux for the two sources, respectively. This implies that the Milagro emission is either extended over a much larger area than our point-spread function or it must be peaked at energies beyond 1 TeV, resulting in a photon index harder than 2.2 in the TeV band.}, keywords = {ISM: supernova remnants, pulsars: individual: PSR J1957+2831 LAT PSR J1954+2836 LAT PSR J1958+2846}, doi = {10.1088/0004-637X/725/2/1629}, url = {http://adsabs.harvard.edu/abs/2010ApJ...725.1629A}, author = {Aleksi{\'c}, J. and Antonelli, L.~A. and Antoranz, P. and Backes, M. and Barrio, J.~A. and Bastieri, D. and Becerra Gonz{\'a}lez, J. and Bednarek, W. and Berdyugin, A. and Berger, K. and Bernardini, E. and Biland, A. and Blanch, O. and Bock, R.~K. and Boller, A. and Bonnoli, G. and Bordas, P. and Borla Tridon, D. and Bosch-Ramon, V. and Bose, D. and Braun, I. and Bretz, T. and Camara, M. and Carmona, E. and Carosi, A. and Colin, P. and Contreras, J.~L. and Cortina, J. and Covino, S. and Dazzi, F. and De Angelis, A. and De Cea del Pozo, E. and De Lotto, B. and De Maria, M. and De Sabata, F. and Delgado Mendez, C. and Diago Ortega, A. and Doert, M. and Dom{\'\i}nguez, A. and Dominis Prester, D. and Dorner, D. and Doro, M. and Elsaesser, D. and Errando, M. and Ferenc, D. and Fonseca, M.~V. and Font, L. and Garc{\'\i}a L{\'o}pez, R.~J. and Garczarczyk, M. and Gaug, M. and Giavitto, G. and Godinovi{\'c}, N. and Hadasch, D. and Herrero, A. and Hildebrand, D. and H{\"o}hne-M{\"o}nch, D. and Hose, J. and Hrupec, D. and Jogler, T. and Klepser, S. and Kr{\"a}henb{\"u}hl, T. and Kranich, D. and Krause, J. and La Barbera, A. and Leonardo, E. and Lindfors, E. and Lombardi, S. and Longo, F. and L{\'o}pez, M. and Lorenz, E. and Majumdar, P. and Maneva, G. and Mankuzhiyil, N. and Mannheim, K. and Maraschi, L. and Mariotti, M. and Mart{\'\i}nez, M. and Mazin, D. and Meucci, M. and Miranda, J.~M. and Mirzoyan, R. and Miyamoto, H. and Mold{\'o}n, J. and Moralejo, A. and Nieto, D. and Nilsson, K. and Orito, R. and Oya, I. and Paoletti, R. and Paredes, J.~M. and Partini, S. and Pasanen, M. and Pauss, F. and Pegna, R.~G. and M. A. P{\'e}rez-Torres and Persic, M. and Peruzzo, L. and Pochon, J. and Prada, F. and Prada Moroni, P.~G. and Prandini, E. and Puchades, N. and Puljak, I. and Reichardt, I. and Reinthal, R. and Rhode, W. and Rib{\'o}, M. and Rico, J. and Rissi, M. and R{\"u}gamer, S. and Saggion, A. and Saito, K. and Saito, T.~Y. and Salvati, M. and S{\'a}nchez-Conde, M. and Satalecka, K. and Scalzotto, V. and Scapin, V. and Schultz, C. and Schweizer, T. and Shayduk, M. and Sierpowska-Bartosik, A. and Sillanp{\"a}{\"a}, A. and Sitarek, J. and Sobczynska, D. and Spanier, F. and Spiro, S. and Stamerra, A. and Steinke, B. and Storz, J. and Strah, N. and Struebig, J.~C. and Suri{\'c}, T. and Takalo, L. and Tavecchio, F. and Temnikov, P. and Terzi{\'c}, T. and Tescaro, D. and Teshima, M. and Torres, D.~F. and Vankov, H. and Wagner, R.~M. and Weitzel, Q. and Zabalza, V. and Zandanel, F. and Zanin, R.} }