The rates of core-collapse supernovae in disturbed/interacting host galaxies, and the multiple supernova population in the starburst galaxy Arp 299
Constraints on supernova (SN) progenitors can be made through studying the environments within which they are found within host galaxies. However, core-collapse (CC) SNe can also be used as tracers of high mass star formation (SF). Therefore we can use the distribution of different CC SN types to infer properties of host galaxy SF in galaxies of different types. We present results on the radial distribution of CC SNe in disturbed and undisturbed host galaxies. We find that the type Ibc SNe are much more centrally concentrated than the type II SNe in the disturbed hosts than in the undisturbed sample. This implies that the IMF in the central regions of these disturbed galaxies is biased towards higher mass stars, given that type Ibc supernova are likely to trace higher mass progenitor stars than SNe type II. We also present a case study of the multiple SN population of the starburst system Arp 299 where we see this same process in action.
Extinction corrections for high-z core collapse SN rates
I will present recent results on the core collapse SN rate to redshift z~1 and discuss issues involved in deriving intrinsic rates from a sample of observed SNe. This includes correcting for extinction in the host galaxies as well as taking into account the fraction of SNe that are hidden in highly dust enshrouded environments in LIRGs and ULIRGs. These effects are expected to increase with redshift since in general, shorter rest-frame wave-lengths are observed at higher redshifts. In addition, the fraction of the star formation hidden from optical searches in LIRGs and ULIRGs is expected to increase rapidly towards redshift z~1. Unless properly corrected for, errors in derived core collapse SN rates at z~1 will be dominated by these effects.
Supernovae in Dense Environments - SN 2009kn the Twin of SN 1994W?
We have conducted multiband photometric and spectroscopic follow-up of narrow-line Type II (IIn) supernova (SN) 2009kn spanning 20-516 days from the discovery. The spectra of SN 2009kn are dominated by narrow Balmer lines (FWHM = 1100 km/s) indicating strong interaction with the circumstellar medium. Both the photometric and spectroscopic evolution of SN 2009kn resembles the behavior of SN 1994W, the nature of which has been explained by two very different models, and which we can test with the new well sampled dataset of SN 2009kn. In normal galaxies Type IIn SNe are relatively rare, ~5% of all core-collapse SNe. However, in the nuclear regions of luminous (L_IR > 10^11 L_sun) and ultraluminous (L_IR > 10^12 L_sun) infrared galaxies such SNe showing strong interaction with the surrounding medium might be more common as indicated by recent radio observations. Detailed studies of Type IIn SNe are therefore interesting also in this aspect.
The luminosity functions of SNe from the Lick Observatory Supernova Search (LOSS)
The Lick Observatory Supernova Search (LOSS), using the robotic 30-inch Katzman Automatic Imaging Telescope (KAIT), has discovered over 800 SNe in the past decade, and is one of the most successful nearby SN searches. In this talk, I will discuss the derivation of the luminosity functions of SNe from a "complete" sample. We use the followup R band and unfiltered search observations to derive an R-band LF for SNe Ia, Ibc, and II. Moreover, multi-color (BVRI) LFs for SNe Ia are also derived. Investigation of the LFs in different colors, and in galaxies of different types provide us insights into the physical (such as explosion mechanism) and observational (such as reddening within the host galaxies) properties of SNe.
Multiwavelength properties of Wolf-Rayet galaxies
In this talk I will present a detailed analysis of a sample of Wolf-Rayet (WR) galaxies using multiwavelength data, which include deep optical/NIR images and spectroscopy, UV and FIR data, and 21-cm HI and 20-cm radio-continuum data. This kind of galaxies will very probably host SNe in the near future and, indeed, the feedback from the massive stars (both supernova explosions and the effects of the stellar winds) is very important to understand their physical and chemical properties. Our WR galaxy sample includes both low metallicity, low mass star-forming galaxies and high metallicity, high mass spiral galaxies. We studied the spatial localization of the WR-rich clusters within each galaxy via the detection of the blue and red WR bumps and derived an empirical estimation of the WR/O ratio considering metallicity-dependent WR luminosities. We analyzed the relationships between stellar and gas mass, metallicity, star-formation rate, stellar populations and dust content in these starbursts. The main finding of our analysis is that interaction processes with dwarf objects or diffuse HI clouds are common in Wolf-Rayet galaxies, supporting the hypothesis that galaxy interaction trigger star formation activity in this kind of starburst galaxies (Lopez-Sanchez 2010, A&A, 521, 63).
Adaptive Optics assisted searches for SNe in luminous infrared galaxies
A substantial fraction of star formation (SF) and hence of the core-collapse supernovae (CCSNe) in the Universe is hidden behind dust. At higher-z obscured star formation in luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) actually dominates over SF seen in the UV and optical. These same objects are expected to hide in their nuclear regions large numbers of undetected CCSNe. In this talk I describe our ongoing efforts using near-IR adaptive optics imaging with Gemini-N and VLT to obtain the most complete picture so far of the SN activity in the nuclear regions of local LIRGs. I will summarise what we can learn from the results already obtained.
SN 1996cr: Trying to Resolve the Shock in the Brightest Radio Supernova
Supernova 1996cr is of Type IIn, and in radio, ranks as the brightest ever discovered. It is also one of the closest, being located in the Circinus Galaxy (ESO 97-G13) at a distance of only ~3.8 Mpc. SN 1996cr is bright both at radio and X-ray wavelengths, indicating strong interaction with the circumstellar medium left over from the progenitor. We report on our VLBI observations with the Australian Long Baseline Array at 8.4 GHz and discuss our results. We determine the size of the supernova and constrain the expansion velocity, which we compare with predictions from theoretical calculations.
Infrared SN search to probe supernova progenitor scenario
We attempt to measure the SN rate in starburst galaxies to test the relation between FIR luminosity and star formation rate. To this aim we performed an infrared search for supernovae in starburst galaxies, using HAWKI@VLT. We obtained a total of ~100 visits during the periods 83 and 85. All data were reduced and analyzed and we found 3 candidates in P83 and 3 SNe in P85. In one case we obtained the discovery image (SN2010hp). I will present the data reduction tecnique, the experiments for determining the detection efficiency and the simulation tools. We computed the SN rate and, as in previous experiments, this value is lower than expected from FIR luminosity. We will analyze the possible alternatives explanation to this.
Galaxy evolution models: the SN time delays and the star formation histories
By using the chemical evolution models from Mollá & Díaz (2005), we analyze the supernova rates obtained for spiral disks and irregular and low mass galaxies and their relation with the star formation histories, colors and stellar masses.
Faint supernovae or supernova impostors?
We label as "supernova impostors" a family of eruptive variables with observed properties resembling those of type IIn supernovae. However, contrary to real supernova explosions, the star (which is usually a "luminous blue variable") survive the eruptive episodes. In this talk I will present recent observations of a few interesting supernova impostors, including some cases of objects whose nature (real SN or SN impostor) is still debated.
Radio supernova searches in local (U)LIRGs
I'll present some results of some radio supernova factories found in starbust galaxies, with emphasis on Arp 299, where our group in Granada is leading a continuing effort at very high resolution (~few milliarseconds) and sensitivity (down to L_radio ~10^26 erg/s/Hz), using VLBI. I will also present our attempts to probe the hidden SN population in local (U)LIRGs using the EVLA on a sample of 11 bright LIRGs, and the eMERLIN on a sample of 42 bright LIRGs.
The CHASE-MiniTAO infrared survey
I will present the preliminary results of the CHASE-MiniTAO K band Supernova search. The survey started in October 2010 with the aim of discover SNe in moderate star forming galaxies (like the "Milky Way") suffering an intermediate degree of extinction (Av < 15). The galaxy sample is composed by very nearby (vr < 1500 km/sec) late type galaxies. For the observations we use 10% Chilean time on the MiniTAO 1m telescope installed by the Univerisity of Tokyo at the Chajnantor summit at 5600 meter above sea level. The instrument is still in the commissioning face, therefore the search is proceeding relatively slow. Nevertheless, we are confident that when the telescope will be fully in operation, we will able to discover that are invisible to the present optical searched (i.e. PTF, Pan-STARRS, LOSS).
The progenitor system of the Type IIb supernova 2001ig
The late-time radio light curve of SN 2001ig showed remarkable quasi-periodic fluctuations indicative of modulation of the circumstellar medium, perhaps by a massive binary companion that could have survived the explosion. Subsequent Gemini imaging revealed an apparent A/F supergiant star, while a Gemini spectrum shows weak He II 4686 emission attributed to a Wolf-Rayet star. We propose that the star which exploded as SN 2001ig was itself an even more massive Wolf-Rayet star.
Evidence for Type Ia Supernova Diversity from the Ultraviolet Observations with the Hubble Space Telescope
We present ultraviolet (UV) spectroscopy and photometry of four type Ia supernovae (SNe Ia) (SNe 2004dt, 2004ef, 2005M, and 2005cf) obtained with the HST ACS High Resolution Channel (HRC) during Cycle 13. These data set provide the unique spectral time series down to 200 nm. Significant diversity is seen in the UV region (~200-350 nm) of the near maximum-light spectra for this small sample. The corresponding photometric data, together with archival data of the SWIFT Ultraviolet/Optical Telescope observations, provide further evidence of increased dispersion in the UV emission with respect to the optical. The peak luminosities measured in uvw1/F250W are found to correlate with the B-band light-curve shape parameter dm15, but with much larger scatter by contrast with the correlation in the broadband B (e.g., ~0.4 mag versus ~0.2 mag for those with 0.8 < dm15 < 1.7 mag). SN 2004dt is found as an outlier of this correlation (at >3 sigmas), being brighter than the normal SNe Ia such as SN 2005cf by ~0.9 mag and ~2.0 mag in the uvw1/F250W filters, respectively. Contemporary models cannot explain such a large discrepancy by changes in the abundance of the iron-group elements of the progenitor. Interaction of the circumstellar material with the ejecta of the SN may contribute to the UV excess, but detailed modeling is needed to quantify this process.
Return to workshop home page.
Date Last Modified: 22 June 2011