@article {233, title = {{Excitation Mechanisms for HCN (1-0) and HCO+ (1-0) in Galaxies from the Great Observatories All-sky LIRG Survey}}, journal = {ArXiv e-prints}, year = {2015}, keywords = {Astrophysics - Astrophysics of Galaxies}, url = {http://adsabs.harvard.edu/abs/2015arXiv150907512P}, author = {Privon, G.~C. and Herrero-Illana, R. and Evans, A.~S. and Iwasawa, K. and Perez-Torres, M.~A. and Armus, L. and Diaz-Santos, T. and Murphy, E.~J. and Stierwalt, S. and Aalto, S. and Mazzarella, J.~M. and Barcos-Munoz, L. and Borish, H.~J. and Inami, H. and Kim, D.-C. and Treister, E. and Surace, J.~A. and Lord, S. and Conway, J. and Frayer, D.~T. and Alberdi, A.} } @article {214, title = {{Exploring the molecular chemistry and excitation in obscured luminous infrared galaxies: An ALMA mm-wave spectral scan of NGC 4418}}, journal = {ArXiv e-prints}, year = {2015}, keywords = {Astrophysics - Astrophysics of Galaxies}, author = {Costagliola, F. and Sakamoto, K. and Muller, S. and Mart{\'\i}n, S. and Aalto, S. and Harada, N. and van der Werf, P. and Viti, S. and Garcia-Burillo, S. and Spaans, M.} } @article {2014MNRAS.444L..68R, title = {{Episodic star formation in a group of LAEs at z = 5.07}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {444}, year = {2014}, pages = {L68-L72}, abstract = {We are undertaking a search for high-redshift low-luminosity Lyman Alpha sources in the SHARDS (Survey for High-z Absorption Red and Dead Sources) survey. Among the pre-selected Lyman Alpha sources two candidates were spotted, located 3.19 arcsec apart, and tentatively at the same redshift. Here, we report on the spectroscopic confirmation with Gran Telescopio Canarias of the Lyman Alpha emission from this pair of galaxies at a confirmed spectroscopic redshifts of z=5.07. Furthermore, one of the sources is interacting/merging with another close companion that looks distorted. Based on the analysis of the spectroscopy and additional photometric data, we infer that most of the stellar mass of these objects was assembled in a burst of star formation 100 Myr ago. A more recent burst (2 Myr old) is necessary to account for the measured Lyman Alpha flux. We claim that these two galaxies are good examples of Lyman Alpha sources undergoing episodic star formation. Besides, these sources very likely constitute a group of interacting Lyman Alpha emitters (LAEs).}, keywords = {galaxies: high-redshift}, doi = {10.1093/mnrasl/slu099}, url = {http://adsabs.harvard.edu/abs/2014MNRAS.444L..68R}, author = {Rodr{\'\i}guez-Espinosa, J.~M. and Gonz{\'a}lez-Mart{\'\i}n, O. and Castro-Rodr{\'\i}guez, N. and P. P{\'e}rez-Gonz{\'a}lez and Mas-Hesse, J.~M. and Mu{\~n}oz-Tu{\~n}{\'o}n, C. and Cava, A. and Cardiel, N. and Cabrera-Lavers, A. and Gallego, J. and Hern{\'a}n-Caballero, A. and Herrera-Ruiz, N. and N. Ram{\'\i}rez-Olivencia} } @article {2012A\&A...543A..72R, title = {{e-MERLIN and VLBI observations of the luminous infrared galaxy IC 883: a nuclear starburst and an AGN candidate revealed}}, journal = {Astronomy and Astrophysics}, volume = {543}, year = {2012}, month = {jul}, pages = {A72}, abstract = {Context. The high star formation rates of luminous infrared galaxies (LIRGs) make them ideal places for core-collapse supernova (CCSN) searches. Massive star formation can often be found in coexistence with an active galactic nucleus (AGN), contributing jointly to the energy source of LIRGs. At radio frequencies, where light is unaffected by dust extinction, it is possible to detect compact components within the innermost LIRG nuclear regions, such as SNe and SN remnants, as well as AGN buried deep in the LIRG nuclei.
Aims: Our study of the LIRG IC 883 aims at: (i) investigating the parsec-scale radio structure of the (circum-)nuclear regions of IC 883; (ii) detecting at radio frequencies the two recently reported circumnuclear SNe 2010cu and 2011hi, which were discovered by near-IR (NIR) adaptive optics observations of IC 883; and (iii) further investigating the nature of SN 2011hi at NIR wavelengths.
Methods: We used the electronic European very long baseline interferometry (VLBI) Network (e-EVN) at 5 GHz, and the electronic Multi-Element Remotely Linked Interferometer Network (e-MERLIN) at 6.9 GHz, to observe contemporaneously the LIRG IC 883 at high angular-resolution (from tens to hundreds of milliarcsec) and with high sensitivity ({\l}t}70 {$μ$}Jy), complemented by archival VLBI data at 5 GHz and 8.4 GHz. We also used the Gemini North telescope to obtain late-time JHK photometry for SN 2011hi.
Results: The circumnuclear regions traced by e-MERLIN at 6.9 GHz have an extension of \~{} 1 kpc, at a position angle of 130{\deg}, and show a striking double-sided structure, which very likely corresponds to a warped rotating ring, in agreement with previous studies. Our e-EVN observations at 5 GHz and complementary archival VLBI data at 5 GHz and 8.4 GHz, reveal various milliarcsec compact components in the nucleus of IC 883. A single compact source, an AGN candidate, dominates the emission at both nuclear and circumnuclear scales, as imaged with the e-EVN and e-MERLIN, respectively. The other milliarcsec components are strongly indicative of ongoing nuclear CCSN activity. Our e-EVN observations also provided upper limits to the radio luminosity of the two SNe in IC 883 recently discovered at NIR wavelengths. We refine the classification of SN 2011hi as a Type IIP SN according to our latest epoch of Gemini North observations acquired in 2012, in agreement with a low-luminosity radio SN nature. We estimate a CCSN rate lower limit of 1.1$_{-0.6}$$^{+1.3}$ yr$^{-1}$ for the entire galaxy, based on three nuclear radio SNe and the circumnuclear SNe 2010cu and 2011hi.}, keywords = {galaxies: individual: IC 883, galaxies: starburst, radiation mechanisms: non-thermal, radio lines: stars}, doi = {10.1051/0004-6361/201218816}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...543A..72R}, author = {Romero-Ca{\~n}izales, C. and M. A. P{\'e}rez-Torres and Alberdi, A. and Argo, M.~K. and Beswick, R.~J. and Kankare, E. and Batejat, F. and Efstathiou, A. and Mattila, S. and Conway, J.~E. and Garrington, S.~T. and Muxlow, T.~W.~B. and Ryder, S.~D. and V{\"a}is{\"a}nen, P.} } @article {2012A\&A...540L...5H, title = {{Evidence of nuclear disks in starburst galaxies from their radial distribution of supernovae}}, journal = {Astronomy and Astrophysics}, volume = {540}, year = {2012}, pages = {L5}, abstract = {Galaxy-galaxy interactions are expected to be responsible for triggering massive star formation and possibly accretion onto a supermassive black hole, by providing large amounts of dense molecular gas down to the central kiloparsec region. Several scenarios to drive the gas further down to the central \~{}100 pc, have been proposed, including the formation of a nuclear disk around the black hole, where massive stars would produce supernovae. Here, we probe the radial distribution of supernovae and supernova remnants in the nuclear regions of the starburst galaxies M 82, Arp 299-A, and Arp 220, by using high-angular resolution ({\l}sim} 0.{\textquoteright}{\textquoteright}1) radio observations published in the literature (for M 82 and Arp 220), or obtained by ourselves from the European VLBI Network (Arp 299-A). Our main goal was to characterize the nuclear starbursts in those galaxies and thus test scenarios that propose that nuclear disks of sizes \~{}100 pc form in the central regions of starburst galaxies. We obtained the radial distribution of supernovae (SNe) in the nuclear starbursts of M 82, Arp 299-A, and Arp 220, and derived scale-length values for the putative nuclear disks powering the bursts in those central regions. The scale lengths for the (exponential) disks range from \~{}20-30 pc for Arp 299-A and Arp 220, up to \~{}140 pc for M 82. The radial distribution of SNe for the nuclear disks in Arp 299-A and Arp 220 is also consistent with a power-law surface density profile of exponent {$\gamma$} = 1, as expected from detailed hydrodynamical simulations of nuclear disks. Our results support scenarios where a nuclear disk of size \~{}100 pc is formed in (U)LIRGs, and sustained by gas pressure, in which case the accretion onto the black hole could be lowered by supernova feedback. Appendices are available in electronic form at http://www.aanda.org}, keywords = {galaxies: individual: Arp 299-A, galaxies: luminosity function, galaxies: starburst, mass function, radiation mechanisms: non-thermal, radio continuum: stars, supernovae: general}, doi = {10.1051/0004-6361/201118545}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...540L...5H}, author = {R. Herrero-Illana and M. A. P{\'e}rez-Torres and Alberdi, A.} } @article {2012MNRAS.422..510R, title = {{EVN observations of the farthest and brightest ULIRGs in the local Universe: the case of IRAS 23365+3604}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {422}, year = {2012}, month = {may}, pages = {510-520}, abstract = {We present high-resolution, high-sensitivity radio images of the ultra-luminous infrared galaxy (ULIRG) IRAS 23365+3604. We performed contemporaneous observations at 1.7 and 5.0 GHz, in three epochs separated by 1 year from each other, with the European Very Long Baseline Interferometry (VLBI) Network (EVN). We also present complementary Multi-Element Radio Linked Interferometry Network (MERLIN) at 1.6 and 5.0 GHz, and archival Very Large Array data, taken at 1.4 and 4.9 GHz. We find that the emission at {\tilde}5.0 GHz remains quite compact as seen at different resolutions, whereas at {\tilde}1.7 GHz, high-resolution imaging reveals some extended structure. The nuclear region has an approximate linear size of 200 pc and shows the presence of two main emission components: (i) one with a composite spectrum due to ongoing non-thermal activity (probably due to recently exploded supernovae and the presence of an active galactic nucleus), and (ii) the other with a steep spectrum, likely dominated by an old population of radio emitters, such as supernova remnants. Radiative losses are important, so re-acceleration or replenishment of new electrons is necessary. We estimate a magnetic field strength of {\tilde} 18 {$μ$}G at galactic and {\tilde} 175 {$μ$}G at nuclear scales, which are typical for galaxies in advanced mergers.}, keywords = {galaxies: individual: IRAS 23365+3604, galaxies: starburst, radio continuum: general}, doi = {10.1111/j.1365-2966.2012.20627.x}, url = {http://adsabs.harvard.edu/abs/2012MNRAS.422..510R}, author = {Romero-Ca{\~n}izales, C. and M. A. P{\'e}rez-Torres and Alberdi, A.} } @article {2011A\&A...529A..47M, title = {{Electron cooling and the connection between expansion and flux-density evolution in radio supernovae}}, journal = {Astronomy and Astrophysics}, volume = {529}, year = {2011}, month = {may}, pages = {A47}, abstract = {{Radio supernovae (RSNe) are weak and rare events. Their typical maximum radio luminosities are of the order of only 10$^{27}$ erg s$^{-1}$ Hz$^{-1}$. There are, however, very few cases of relatively bright (and/or close) RSNe, from which the expansion of the shock and the radio light curves at several frequencies have been monitored covering several years. Applying the standard model of radio emission from supernovae, it is possible to relate the defining parameters of the modelled expansion curve to those of the modelled light curves in a simple algebraic way by assuming an evolution law for the magnetic field and for the energy density of the population of synchrotron-emitting electrons. However, cooling mechanisms of the electrons may considerably affect this connection between light curves and expansion curve, and lead to wrong conclusions on the details of the electron acceleration and/or on the CSM radial density profile. We study how electron cooling modifies the flux-density decay rate of RSNe for a set of plausible/realistic values of the magnetic field and for different expansion regimes. We use these results to estimate the magnetic fields of different RSNe observed to date and compare them to those obtained by assuming energy equipartition between particles and magnetic fields. For some of the best monitored RSNe, for which deceleration measurements, optically thin spectral index, and power-law time decay have been observed (SN 1979C, SN 1986J, SN 1993J, and SN 2008iz), we find self-consistent solutions for the index of the power-law circumstellar density profile (s = 2 for all cases), the index of the power-law relativistic electron population (rather steep values}, keywords = {acceleration of particles, radiation mechanisms: nonthermal, radio continuum: stars, supernovae: general}, doi = {10.1051/0004-6361/201016105}, url = {http://adsabs.harvard.edu/abs/2011A\%26A...529A..47M}, author = {Mart{\'\i}-Vidal, I. and M. A. P{\'e}rez-Torres and Brunthaler, A.} } @article {2011MNRAS.410.2556D, title = {{Extragalactic background light inferred from AEGIS galaxy-SED-type fractions}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {410}, year = {2011}, month = {feb}, pages = {2556-2578}, abstract = {The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for {$\gamma$}-ray astronomy, but the overall spectrum of the EBL between 0.1 and 1000 {$μ$}m has never been determined directly from galaxy spectral energy distribution (SED) observations over a wide redshift range. The evolving, overall spectrum of the EBL is derived here utilizing a novel method based on observations only. This is achieved from the observed evolution of the rest-frame K-band galaxy luminosity function up to redshift 4, combined with a determination of galaxy-SED-type fractions. These are based on fitting Spitzer Wide-Area Infrared Extragalactic Survey (SWIRE) templates to a multiwavelength sample of about 6000 galaxies in the redshift range from 0.2 to 1 from the All-wavelength Extended Groth Strip International Survey (AEGIS). The changing fractions of quiescent galaxies, star-forming galaxies, starburst galaxies and active galactic nucleus (AGN) galaxies in that redshift range are estimated, and two alternative extrapolations of SED types to higher redshifts are considered. This allows calculation of the evolution of the luminosity densities from the ultraviolet (UV) to the infrared (IR), the evolving star formation rate density of the Universe, the evolving contribution to the bolometric EBL from the different galaxy populations including AGN galaxies and the buildup of the EBL. Our EBL calculations are compared with those from a semi-analytic model, another observationally based model and observational data. The EBL uncertainties in our modelling based directly on the data are quantified, and their consequences for attenuation of very-high-energy {$\gamma$}-rays due to pair production on the EBL are discussed. It is concluded that the EBL is well constrained from the UV to the mid-IR, but independent efforts from IR and {$\gamma$}-ray astronomy are needed in order to reduce the uncertainties in the far-IR.}, keywords = {cosmology: observations, diffuse radiation, galaxies: evolution, galaxies: formation, infrared: diffuse background}, doi = {10.1111/j.1365-2966.2010.17631.x}, url = {http://adsabs.harvard.edu/abs/2011MNRAS.410.2556D}, author = {Dom{\'\i}nguez, A. and Primack, J.~R. and Rosario, D.~J. and Prada, F. and Gilmore, R.~C. and Faber, S.~M. and Koo, D.~C. and Somerville, R.~S. and M. A. P{\'e}rez-Torres and P. P{\'e}rez-Gonz{\'a}lez and Huang, J.-S. and Davis, M. and Guhathakurta, P. and Barmby, P. and Conselice, C.~J. and Lozano, M. and Newman, J.~A. and Cooper, M.~C.} }