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251. Updated Type II supernova Hubble diagram
ID:
ivo://CDS.VizieR/J/A+A/611/A25
Title:
Updated Type II supernova Hubble diagram
Short Name:
J/A+A/611/A25
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present photometry and spectroscopy of nine Type II-P/L supernovae (SNe) with redshifts in the 0.045~<z~<0.335 range, with a view to re-examining their utility as distance indicators. Specifically, we apply the expanding photosphere method (EPM) and the standardized candle method (SCM) to each target, and find that both methods yield distances that are in reasonable agreement with each other. The current record-holder for the highest-redshift spectroscopically confirmed SN II-P is PS1-13bni (z=0.335^+0.009^_-0.012_), and illustrates the promise of Type II SNe as cosmological tools. We updated existing EPM and SCM Hubble diagrams by adding our sample to those previously published. Within the context of Type II SN distance measuring techniques, we investigated two related questions. First, we explored the possibility of utilising spectral lines other than the traditionally used FeII {lambda}5169 to infer the photospheric velocity of SN ejecta. Using local well-observed objects, we derive an epoch-dependent relation between the strong Balmer lines H{alpha}, H{beta} and FeII {lambda}5169 velocities that is applicable 30 to 40 days post-explosion. Motivated in part by the continuum of key observables such as rise time and decline rates exhibited from II-P to II-L SNe, we assessed the possibility of using Hubble-flow Type II-L SNe as distance indicators. These yield similar distances as the Type II-P SNe. Although these initial results are encouraging, a significantly larger sample of SNe II-L would be required to draw definitive conclusions.
252. UVOT light curves of supernovae
ID:
ivo://CDS.VizieR/J/AJ/137/4517
Title:
UVOT light curves of supernovae
Short Name:
J/AJ/137/4517
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present ultraviolet (UV) observations of supernovae (SNe) obtained with the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is the largest sample of UV light curves from any single instrument and covers all major SN types and most subtypes.
253. UVOT photometry of Super-Chandrasekhar mass SNe Ia
ID:
ivo://CDS.VizieR/J/ApJ/787/29
Title:
UVOT photometry of Super-Chandrasekhar mass SNe Ia
Short Name:
J/ApJ/787/29
Date:
21 Oct 2021
Publisher:
CDS
Description:
Among Type Ia supernovae (SNe Ia), a class of overluminous objects exist whose ejecta mass is inferred to be larger than the canonical Chandrasekhar mass. We present and discuss the UV/optical photometric light curves, colors, absolute magnitudes, and spectra of three candidate Super-Chandrasekhar mass SNe - 2009dc, 2011aa, and 2012dn - observed with the Swift Ultraviolet/Optical Telescope. The light curves are at the broad end for SNe Ia, with the light curves of SN 2011aa being among the broadest ever observed. We find all three to have very blue colors which may provide a means of excluding these overluminous SNe from cosmological analysis, though there is some overlap with the bluest of "normal" SNe Ia. All three are overluminous in their UV absolute magnitudes compared to normal and broad SNe Ia, but SNe 2011aa and 2012dn are not optically overluminous compared to normal SNe Ia. The integrated luminosity curves of SNe 2011aa and 2012dn in the UVOT range (1600-6000 {AA}) are only half as bright as SN 2009dc, implying a smaller ^56^Ni yield. While it is not enough to strongly affect the bolometric flux, the early time mid-UV flux makes a significant contribution at early times. The strong spectral features in the mid-UV spectra of SNe 2009dc and 2012dn suggest a higher temperature and lower opacity to be the cause of the UV excess rather than a hot, smooth blackbody from shock interaction. Further work is needed to determine the ejecta and ^56^Ni masses of SNe 2011aa and 2012dn and to fully explain their high UV luminosities.
254. Velocities and EW of PTF SNe Ia
ID:
ivo://CDS.VizieR/J/MNRAS/444/3258
Title:
Velocities and EW of PTF SNe Ia
Short Name:
J/MNRAS/444/3258
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an investigation of the optical spectra of 264 low-redshift (z<0.2) Type Ia supernovae (SNe Ia) discovered by the Palomar Transient Factory, an untargeted transient survey. We focus on velocity and pseudo-equivalent width measurements of the SiII 4130, 5972, and 6355{AA} lines, as well those of the CaII near-infrared (NIR) triplet, up to +5days relative to the SN B-band maximum light. We find that a high-velocity component of the CaII NIR triplet is needed to explain the spectrum in ~95% of SNe Ia observed before -5days, decreasing to ~80% at maximum. The average velocity of the CaII high-velocity component is ~8500km/s higher than the photospheric component. We confirm previous results that SNe Ia around maximum light with a larger contribution from the high-velocity component relative to the photospheric component in their CaII NIR feature have, on average, broader light curves and lower CaII NIR photospheric velocities. We find that these relations are driven by both a stronger high-velocity component and a weaker contribution from the photospheric CaII NIR component in broader light curve SNe Ia. We identify the presence of CII in very-early-time SN Ia spectra (before -10days), finding that >40% of SNe Ia observed at these phases show signs of unburnt material in their spectra, and that CII features are more likely to be found in SNe Ia having narrower light curves.
255. X-ray emission from 28 SNe (IIn, Ibn or SLSN-I)
ID:
ivo://CDS.VizieR/J/ApJ/763/42
Title:
X-ray emission from 28 SNe (IIn, Ibn or SLSN-I)
Short Name:
J/ApJ/763/42
Date:
21 Oct 2021
Publisher:
CDS
Description:
Here we report on a search, using Swift/XRT and Chandra, for X-ray emission from 28 SNe that belong to classes whose progenitors are suspected to be embedded in dense circumstellar matter (CSM). Our sample includes 19 Type IIn SNe, one Type Ibn SN, and eight hydrogen-poor superluminous SNe (SLSN-I such as SN 2005ap). Two SNe (SN 2006jc and SN 2010jl) have X-ray properties that are roughly consistent with the expectation for X-rays from a collisionless shock in optically thick CSM. However, the X-ray emission from SN 2006jc can also be explained as originating in an optically thin region. Thus, we propose that the optical light curve of SN 2010jl is powered by shock breakout in CSM. We suggest that two other events (SN 2010al and SN 2011ht) were too X-ray bright during the SN maximum optical light to be explained by the shock-breakout model. We conclude that the light curves of some, but not all, SNe IIn/Ibn are powered by shock breakout in CSM. For the rest of the SNe in our sample, including all of the SLSN-I events, our X-ray limits are not deep enough and were typically obtained too early (i.e., near the SN maximum light) for definitive conclusions about their nature. Late-time X-ray observations are required in order to further test whether these SNe are indeed embedded in dense CSM.
256. YJK for Type Ia supernovae
ID:
ivo://CDS.VizieR/J/MNRAS/448/1345
Title:
YJK for Type Ia supernovae
Short Name:
J/MNRAS/448/1345
Date:
21 Oct 2021
Publisher:
CDS
Description:
Type Ia supernovae (SNe Ia) have been proposed to be much better distance indicators at near-infrared (NIR) compared to optical wavelengths - the effect of dust extinction is expected to be lower and it has been shown that SNe Ia behave more like `standard candles' at NIR wavelengths. To better understand the physical processes behind this increased uniformity, we have studied the Y, J and H-filter light curves of 91 SNe Ia from the literature. We show that the phases and luminosities of the first maximum in the NIR light curves are extremely uniform for our sample. The phase of the second maximum, the late-phase NIR luminosity and the optical light-curve shape are found to be strongly correlated, in particular more luminous SNe Ia reach the second maximum in the NIR filters at a later phase compared to fainter objects. We also find a strong correlation between the phase of the second maximum and the epoch at which the SN enters the Lira law phase in its optical colour curve (epochs ~15 to 30d after B-band maximum). The decline rate after the second maximum is very uniform in all NIR filters. We suggest that these observational parameters are linked to the nickel and iron mass in the explosion, providing evidence that the amount of nickel synthesized in the explosion is the dominating factor shaping the optical and NIR appearance of SNe Ia.
257. ZTF early observations of Type Ia SNe. I. LCs
ID:
ivo://CDS.VizieR/J/ApJ/886/152
Title:
ZTF early observations of Type Ia SNe. I. LCs
Short Name:
J/ApJ/886/152
Date:
21 Oct 2021
Publisher:
CDS
Description:
Early-time observations of Type Ia supernovae (SNe Ia) are essential to constrain the properties of their progenitors. In this paper, we present high-quality light curves of 127 SNe Ia discovered by the Zwicky Transient Facility (ZTF) in 2018. We describe our method to perform forced point-spread function photometry, which can be applied to other types of extragalactic transients. With a planned cadence of six observations per night (three g + three r), all of the 127 SNe Ia are detected in both g and r bands more than 10 days (in the rest frame) prior to the epoch of g-band maximum light. The redshifts of these objects range from z=0.0181 to 0.165; the median redshift is 0.074. Among the 127 SNe, 50 are detected at least 14 days prior to maximum light (in the rest frame), with a subset of nine objects being detected more than 17 days before g-band peak. This is the largest sample of young SNe Ia collected to date; it can be used to study the shape and color evolution of the rising light curves in unprecedented detail. We discuss six peculiar events in this sample: one 02cx-like event ZTF18abclfee (SN2018crl), one Ia-CSM SN ZTF18aaykjei (SN2018cxk), and four objects with possible super-Chandrasekhar mass progenitors: ZTF18abhpgje (SN2018eul), ZTF18abdpvnd (SN2018dvf), ZTF18aawpcel (SN2018cir), and ZTF18abddmrf (SN2018dsx).
258. Zwicky Transient Facility BTS. I.
ID:
ivo://CDS.VizieR/J/ApJ/895/32
Title:
Zwicky Transient Facility BTS. I.
Short Name:
J/ApJ/895/32
Date:
16 Mar 2022 00:25:08
Publisher:
CDS
Description:
The Zwicky Transient Facility (ZTF) is performing a three-day cadence survey of the visible northern sky (~3{pi}) with newly found transient candidates announced via public alerts. The ZTF Bright Transient Survey (BTS) is a large spectroscopic campaign to complement the photometric survey. BTS endeavors to spectroscopically classify all extragalactic transients with m_peak_<~18.5mag in either the g_ZTF_ or r_ZTF_ filters, and publicly announce said classifications. BTS discoveries are predominantly supernovae (SNe), making this the largest flux-limited SN survey to date. Here we present a catalog of 761 SNe, classified during the first nine months of ZTF (2018 April 1-2018 December 31). We report BTS SN redshifts from SN template matching and spectroscopic host-galaxy redshifts when available. We analyze the redshift completeness of local galaxy catalogs, the redshift completeness fraction (RCF; the ratio of SN host galaxies with known spectroscopic redshift prior to SN discovery to the total number of SN hosts). Of the 512 host galaxies with SNe Ia, 227 had previously known spectroscopic redshifts, yielding an RCF estimate of 44%{+/-}4%. The RCF decreases with increasing distance and decreasing galaxy luminosity (for z<0.05, or ~200Mpc, RCF~0.6). Prospects for dramatically increasing the RCF are limited to new multifiber spectroscopic instruments or wide-field narrowband surveys. Existing galaxy redshift catalogs are only ~50% complete at r~16.9mag. Pushing this limit several magnitudes deeper will pay huge dividends when searching for electromagnetic counterparts to gravitational wave events or sources of ultra-high-energy cosmic rays or neutrinos.

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