@article {2015ApJ...799...11X, title = {{ALMA Observations of Warm Dense Gas in NGC 1614 - Breaking of the Star Formation Law in the Central Kiloparsec}}, journal = {The Astrophysical Journal}, volume = {799}, year = {2015}, month = {jan}, pages = {11}, abstract = {We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the 435 {$μ$}m dust continuum emission in the central kiloparsec of NGC 1614, a local luminous infrared galaxy at a distance of 67.8 Mpc (1$\{$$^{\prime \prime }$$\}$= 329 pc). The CO emission is well resolved by the ALMA beam (0.{\textquoteright}{\textquoteright}26 {\times} 0.{\textquoteright}{\textquoteright}20) into a circumnuclear ring, with an integrated flux of f $_{ CO(6-5)}$ = 898 ({\plusmn} 153) Jy km s$^{-1}$, which is 63({\plusmn} 12)\% of the total CO (6-5) flux measured by Herschel. The molecular ring, located between 100 pc {\l}t} r {\l}t} 350 pc from the nucleus, looks clumpy and includes seven unresolved (or marginally resolved) knots with median velocity dispersion of \~{}40 km s$^{-1}$. These knots are associated with strong star formation regions with {$Σ$}$_{SFR}$ \~{} 100 M $_{\&sun;}$ yr$^{-1}$ kpc$^{-2}$ and {$Σ$} $_{Gas}${\tilde} 10$^{4}$ $\{$M$\}$\_{\sun} pc$^{-2}$. The non-detections of the nucleus in both the CO (6-5) line emission and the 435 {$μ$}m continuum rule out, with relatively high confidence, a Compton-thick active galactic nucleus in NGC 1614. Comparisons with radio continuum emission show a strong deviation from an expected local correlation between {$Σ$}$_{Gas}$ and {$Σ$}$_{SFR}$, indicating a breakdown of the Kennicutt-Schmidt law on the linear scale of \~{}100 pc. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.}, keywords = {galaxies: active, galaxies: evolution, galaxies: general, galaxies: interactions, galaxies: ISM, galaxies: magnetic fields, galaxies: nuclei, galaxies: starburst, submillimeter: galaxies}, doi = {10.1088/0004-637X/799/1/11}, url = {http://adsabs.harvard.edu/abs/2015ApJ...799...11X}, author = {Xu, C.~K. and Cao, C. and Lu, N. and Gao, Y. and Diaz-Santos, T. and R. Herrero-Illana and Meijerink, R. and Privon, G. and Zhao, Y.-H. and Evans, A.~S. and K{\"o}nig, S. and Mazzarella, J.~M. and Aalto, S. and Appleton, P. and Armus, L. and Charmandaris, V. and Chu, J. and Haan, S. and Inami, H. and Murphy, E.~J. and Sanders, D.~B. and Schulz, B. and van der Werf, P.} } @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 {2014MNRAS.440.1052K, title = {{The nature of supernovae 2010O and 2010P in Arp 299 - I. Near-infrared and optical evolution}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {440}, year = {2014}, month = {may}, pages = {1052-1066}, abstract = {We present near-infrared and optical photometry, plus optical spectroscopy of two stripped-envelope supernovae (SNe) 2010O and 2010P that exploded in two different components of an interacting luminous infrared galaxy Arp 299 within only a few days of one another. SN 2010O is found to be photometrically and spectroscopically similar to many normal Type Ib SNe and our multiwavelength observations of SN 2010P suggest it to be a Type IIb SN. No signs of clear hydrogen features or interaction with the circumstellar medium are evident in the optical spectrum of SN 2010P. We derive estimates for the host galaxy line-of-sight extinctions for both SNe, based on both light curve and spectroscopic comparison finding consistent results. These methods are also found to provide much more robust estimates of the SN host galaxy reddening than the commonly used empirical relations between extinction and equivalent width of Na I D absorption features. The SN observations also suggest that different extinction laws are present in different components of Arp 299. For completeness, we study high-resolution pre-explosion images of Arp 299 and find both SNe to be close to, but not coincident with, extended sources that are likely massive clusters. A very simple model applied to the bolometric light curve of SN 2010O implies a rough estimate for the explosion parameters of E$_{k}$ {\ap} 3 {\times} 10$^{51}$ erg, M$_{ej}$ {\ap} 2.9 M$_{\&sun;}$ and M$_{Ni}$ {\ap} 0.16 M$_{\&sun;}$.}, keywords = {galaxies: individual: Arp 299, galaxies: starburst, infrared: galaxies, supernovae: general, supernovae: individual: SN 2010O, supernovae: individual: SN 2010P}, doi = {10.1093/mnras/stt2289}, url = {http://adsabs.harvard.edu/abs/2014MNRAS.440.1052K}, author = {Kankare, E. and Mattila, S. and Ryder, S. and Fraser, M. and Pastorello, A. and Elias-Rosa, N. and Romero-Ca{\~n}izales, C. and Alberdi, A. and Hentunen, V.-P. and R. Herrero-Illana and Kotilainen, J. and M. A. P{\'e}rez-Torres and V{\"a}is{\"a}nen, P.} } @article {2014MNRAS.440.1067R, title = {{The nature of supernovae 2010O and 2010P in Arp 299 - II. Radio emission}}, journal = {Monthly Notices of the Royal Astronomical Society}, volume = {440}, year = {2014}, pages = {1067-1079}, abstract = {We report radio observations of two stripped-envelope supernovae (SNe), 2010O and 2010P, which exploded within a few days of each other in the luminous infrared galaxy Arp 299. Whilst SN 2010O remains undetected at radio frequencies, SN 2010P was detected (with an astrometric accuracy better than 1 milli arcsec in position) in its optically thin phase in epochs ranging from {\tilde}1 to {\tilde}3 yr after its explosion date, indicating a very slow radio evolution and a strong interaction of the SN ejecta with the circumstellar medium. Our late-time radio observations towards SN 2010P probe the dense circumstellar envelope of this SN, and imply dot$\{$M$\}$ [ $\{$M\_$\{${\sun}$\}$ yr\^{}$\{$-1$\}$$\}$] / v\_$\{$wind$\}$ [10 km s\^{}$\{$-1$\}$] =(3.0-5.1) {\times} 10$^{-5}$, with a 5 GHz peak luminosity of {\tilde}1.2 {\times} 10$^{27}$ erg s$^{- 1}$ Hz$^{- 1}$ on day {\tilde}464 after explosion. This is consistent with a Type IIb classification for SN 2010P, making it the most distant and most slowly evolving Type IIb radio SN detected to date.}, keywords = {galaxies: individual: Arp 299, galaxies: starburst, radio continuum: galaxies, supernovae: general, supernovae: individual: SN 2010O, supernovae: individual: SN 2010P}, doi = {10.1093/mnras/stu430}, url = {http://adsabs.harvard.edu/abs/2014MNRAS.440.1067R}, author = {Romero-Ca{\~n}izales, C. and R. Herrero-Illana and M. A. P{\'e}rez-Torres and Alberdi, A. and Kankare, E. and Bauer, F.~E. and Ryder, S.~D. and Mattila, S. and Conway, J.~E. and Beswick, R.~J. and Muxlow, T.~W.~B.} } @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 {2012A\&A...539A.134B, title = {{The nuclear starburst in Arp 299-A: from the 5.0 GHz VLBI radio light-curves to its core-collapse supernova rate}}, journal = {Astronomy and Astrophysics}, volume = {539}, year = {2012}, pages = {A134}, abstract = {Context. The nuclear region of the luminous infrared galaxy (LIRG) Arp 299-A hosts a recent ( {\sime} 10 Myr) intense burst of massive star formation that is expected to lead to numerous core-collapse supernovae (CCSNe). Previous VLBI observations, carried out with the European VLBI Network (EVN) at 5.0 GHz and with the VLBA at 2.3 and 8.4 GHz, resulted in the detection of many compact, bright, non-thermal sources in a region {\l}sim} 150 pc in size.
Aims: We aim to establish the nature of all non-thermal compact components in Arp 299-A, as well as to estimate its core-collapse supernova rate. While the majority of the compact components are expected to be young radio supernovae (RSNe) and supernova remnants (SNRs), a definitive classification is still lacking. Yet, this is very relevant for eventually establishing the CCSN rate, as well as the star formation rate, for this galaxy.
Methods: We used multi-epoch EVN observations taken at 5.0 GHz to image the compact radio sources in the nuclear region of Arp 299-A with milliarcsecond resolution. We also used one single-epoch 5.0 GHz Multi-Element Radio Linked Interferometer Network (MERLIN) observation to image the extended emission in which these compact radio sources are embedded.
Results: We present the first 5.0 GHz radio light-curve (spanning \~{}2.5 yr) of all compact components in the nuclear starburst of Arp 299-A. Twenty-six compact sources are detected, eight of which are new objects. The properties of all detected objects are consistent with them being a mixed population of CCSNe and SNRs. We find clear evidence for at least two new CCSNe, implying a lower limit to the CCSN rate of {$ν$}$_{SN}$ {\gsim} 0.80 SN/yr, indicating that the bulk of the current star formation in Arp 299-A is taking place in the innermost \~{}150 pc.A few more objects show variability consistent with them being recently exploded SNe, but only future observations will clarify this point. Our MERLIN observations trace a region of diffuse extended emission that is cospatial to the region where all compact sources are found. From this diffuse non-thermal radio emission traced by MERLIN we obtain an independent estimate for the CCSN rate, which is in the range {$ν$}$_{SN}$ = 0.40-0.65 SN/yr, in agreement with previous estimates and our direct estimate of the CCSN rate from the compact radio emission.
Conclusions: Our \~{}2.5 yr monitoring of Arp 299-A has allowed us to obtain for the first time a direct estimate of the CCSN rate of {$ν$}$_{SN}$ {\gsim} 0.80 SN/yr for the innermost \~{}150 pc of Arp 299-A.}, keywords = {galaxies: individual: Arp 299, galaxies: luminosity function, galaxies: starburst, mass function, radiation mechanisms: non-thermal, radio continuum: stars, supernovae: general}, doi = {10.1051/0004-6361/201118446}, url = {http://adsabs.harvard.edu/abs/2012A\%26A...539A.134B}, author = {Bondi, M. and M. A. P{\'e}rez-Torres and R. Herrero-Illana and Alberdi, A.} }