From core collapse to superluminous: The rates of massive stellar explosions from the Palomar Transient Factory

We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is CCv=9.10-1.27+1.56× 10-5SNe yr-1Mpc-3, h703 at za = 0.028, and the SESN volumetric rate is SEv=2.41-0.64+0.81× 10-5SNe yr-1Mpc-3, h703. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of SLSN-Iv=35-13+25 SNe yr-1Gpc-3, h703, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ∼1/810+1500-94, and of SLSN-I to all CCSN types of ∼1/3500+2800-720. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM∗ < 9.5 M·) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of 1/300+380-170 and 1/1700+1800-720 for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass

Circumstellar interaction in supernovae in dense environments - an observational perspective

In a supernova explosion, the ejecta interacting with the surrounding circumstellar medium (CSM) give rise to variety of radiation. Since CSM is created from the mass lost from the progenitor star, it carries footprints of the late time evolution of the star. This is one of the unique ways to get a handle on the nature of the progenitor star system. Here, I will focus mainly on the supernovae (SNe) exploding in dense environments, a.k.a. Type IIn SNe. Radio and X-ray emission from this class of SNe have revealed important modifications in their radiation properties, due to the presence of high density CSM. Forward shock dominance of the X-ray emission, internal free-free absorption of the radio emission, episodic or non-steady mass loss rate, asymmetry in the explosion seem to be common properties of this class of SNe.Comment: Fixed minor typos. 31 pages, 9 figures, accepted for publication in Space Science Reviews. Chapter in International Space Science Institute (ISSI) Book on "Supernovae" to be published in Space Science Reviews by Springe

Supernova 2013fc in a circumnuclear ring of a luminous infrared galaxy: the big brother of SN 1998S

We present photometric and spectroscopic observations of SN 2013fc, a bright type II supernova (SN) in a circumnuclear star-forming ring in the luminous infrared galaxy ESO 154-G010, observed as part of the Public ESO Spectroscopic Survey of Transient Objects. SN 2013fc is both photometrically and spectroscopically similar to the well-studied type IIn SN 1998S and to the bright type II-L SN 1979C. It exhibits an initial linear decline, followed by a short plateau phase and a tail phase with a decline too fast for 56Co decay with full γ-ray trapping. Initially, the spectrum was blue and featureless. Later on, a strong broad (˜8000 km s-1) H α emission profile became prominent. We apply a STARLIGHT stellar population model fit to the SN location (observed when the SN had faded) to estimate a high extinction of AV = 2.9 ± 0.2 mag and an age of 10_{-2}^{+3} Myr for the underlying cluster. We compare the SN to SNe 1998S and 1979C and discuss its possible progenitor star considering the similarities to these events. With a peak brightness of B = -20.46 ± 0.21 mag, SN 2013fc is 0.9 mag brighter than SN 1998S and of comparable brightness to SN 1979C. We suggest that SN 2013fc was consistent with a massive red supergiant (RSG) progenitor. Recent mass loss probably due to a strong RSG wind created the circumstellar matter illuminated through its interaction with the SN ejecta. We also observe a near-infrared excess, possibly due to newly condensed dust.</p

Massive stars exploding in a He-rich circumstellar medium - II. The transitional case of SN 2005la

We present photometric and spectroscopic data of the peculiar SN 2005la, an object which shows an optical light curve with some luminosity fluctuations and spectra with comparably strong narrow hydrogen and helium lines, probably of circumstellar nature. The increasing full-width-half-maximum velocity of these lines is indicative of an acceleration of the circumstellar material. SN 2005la exhibits hybrid properties, sharing some similarities with both type IIn supernovae and 2006jc-like (type Ibn) events. We propose that the progenitor of SN 2005la was a very young Wolf-Rayet (WN-type) star which experimented mass ejection episodes shortly before core collapse.Comment: 9 pages, including 6 figures and 4 tables. Minor corrections, 1 figure added. Accepted for publication in MNRA

From core collapse to superluminous: The rates of massive stellar explosions from the Palomar Transient Factory

International audienceWe present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is |$r^\mathrm{CC}_v=9.10_{-1.27}^{+1.56}\times 10^{-5}\, \text{SNe yr}^{-1}\, \text{Mpc}^{-3}\, h_{70}^{3}$| at 〈z〉 = 0.028, and the SESN volumetric rate is |$r^\mathrm{SE}_v=2.41_{-0.64}^{+0.81}\times 10^{-5}\, \text{SNe yr}^{-1}\, \text{Mpc}^{-3}\, h_{70}^{3}$|⁠. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of |$r^\mathrm{SLSN-I}_v=35_{-13}^{+25}\, \text{SNe yr}^{-1}\text{Gpc}^{-3}\, h_{70}^{3}$|⁠, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of |${\sim}1/810^{+1500}_{-94}$|⁠, and of SLSN-I to all CCSN types of |${\sim}1/3500^{+2800}_{-720}$|⁠. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM_* < 9.5 M_⊙) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of |$1/300^{+380}_{-170}$| and |$1/1700^{+1800}_{-720}$| for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass

The volumetric rate of normal type Ia supernovae in the local universe discovered by the Palomar Transient Factory

We present the volumetric rate of normal type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory (PTF). Using strict data-quality cuts, and considering only periods when the PTF maintained a regular cadence, PTF discovered 90 SNe Ia at z ≤ 0.09 in a well-controlled sample over three years of operation (2010–2012). We use this to calculate the volumetric rate of SN Ia events by comparing this sample to simulations of hundreds of millions of SN Ia light curves produced in statistically representative realisations of the PTF survey. This quantifies the recovery efficiency of each PTF SN Ia event, and thus the relative weighting of each event. From this, the volumetric SN Ia rate was found to be rv = 2.43±0.29(stat) +0.33−0.19 (sys) ×10−5SNe yr−1Mpc−3 h370⁠. This represents the most precise local measurement of the SN Ia rate. We fit a simple SN Ia delay-time distribution model, ∝ t−β, to our PTF rate measurement combined with a literature sample of rate measurements from surveys at higher-redshifts. We find β ∼ 1, consistent with a progenitor channel governed by the gravitational in-spiral of binary white dwarfs