Number of results to display per page
Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/56
- Title:
- UVOT, ZTF gri LCs and spectra of the SN Ia 2019yvq
- Short Name:
- J/ApJ/898/56
- Date:
- 16 Mar 2022 00:53:53
- Publisher:
- CDS
- Description:
- Early observations of Type Ia supernovae (SNe Ia) provide essential clues for understanding the progenitor system that gave rise to the terminal thermonuclear explosion. We present exquisite observations of SN 2019yvq, the second observed SN Ia, after iPTF 14atg, to display an early flash of emission in the ultraviolet (UV) and optical. Our analysis finds that SN 2019yvq was unusual, even when ignoring the initial flash, in that it was moderately underluminous for an SN Ia (M_g_~-18.5mag at peak) yet featured very high absorption velocities (v~15000km/s for SiII{lambda}6355 at peak). We find that many of the observational features of SN 2019yvq, aside from the flash, can be explained if the explosive yield of radioactive 56Ni is relatively low (we measure M_56Ni_=0.31+/-0.05M_{sun}_) and it and other iron-group elements are concentrated in the innermost layers of the ejecta. To explain both the UV/optical flash and peak properties of SN 2019yvq we consider four different models: interaction between the SN ejecta and a nondegenerate companion, extended clumps of ^56^Ni in the outer ejecta, a double-detonation explosion, and the violent merger of two white dwarfs. Each of these models has shortcomings when compared to the observations; it is clear additional tuning is required to better match SN 2019yvq. In closing, we predict that the nebular spectra of SN 2019yvq will feature either H or He emission, if the ejecta collided with a companion, strong [CaII] emission, if it was a double detonation, or narrow [OI] emission, if it was due to a violent merger.
- ID:
- ivo://CDS.VizieR/J/ApJ/877/152
- Title:
- UV to NIR light curves of type Ia SN 2017erp
- Short Name:
- J/ApJ/877/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present space-based ultraviolet/optical photometry and spectroscopy with the Swift Ultra-Violet/Optical Telescope and Hubble Space Telescope (HST), respectively, along with ground-based optical photometry and spectroscopy and near-infrared spectroscopy of supernova SN 2017erp. The optical light curves and spectra are consistent with a normal SN Ia. Compared to previous photometric samples in the near-ultraviolet (NUV), SN 2017erp has UV colors that are redder than NUV-blue SNe Ia corrected to similar optical colors. The chromatic difference between SNe 2011fe and 2017erp is dominated by the intrinsic differences in the UV rather than the expected dust reddening. This chromatic difference is similar to the SALT2 color law, derived from rest-frame ultraviolet photometry of higher redshift SNe Ia. Differentiating between intrinsic UV diversity and dust reddening can have important consequences for determining cosmological distances with rest-frame ultraviolet photometry. This ultraviolet spectroscopic series is the first from HST of a normal, albeit reddened, NUV-red SN Ia and is important for analyzing SNe Ia with intrinsically redder NUV colors. We show model comparisons suggesting that metallicity could be the physical difference between NUV-blue and NUV-red SNe Ia, with emission peaks from reverse fluorescence near 3000{AA} implying a factor of ~10 higher metallicity in the upper layers of SN 2017erp compared to SN 2011fe. Metallicity estimates are very model dependent, however, and there are multiple effects in the UV. Further models and UV spectra of SNe Ia are needed to explore the diversity of SNe Ia, which show seemingly independent differences in the near-UV peaks and mid-UV flux levels.
- ID:
- ivo://CDS.VizieR/J/ApJ/898/166
- Title:
- UV to NIR obs. of SN 2019ehk
- Short Name:
- J/ApJ/898/166
- Date:
- 21 Mar 2022 09:18:33
- Publisher:
- CDS
- Description:
- We present panchromatic observations and modeling of the Calcium-rich supernova (SN) 2019ehk in the star-forming galaxy M100 (d~16.2Mpc) starting 10hr after explosion and continuing for ~300days. SN 2019ehk shows a double-peaked optical light curve peaking at t=3 and 15days. The first peak is coincident with luminous, rapidly decaying Swift-XRT-discovered X-ray emission (L_x_~10^41^erg/s at 3days; Lx{propto}t^-3^), and a Shane/Kast spectral detection of narrow H{alpha} and HeII emission lines (v~500km/s) originating from pre-existent circumstellar material (CSM). We attribute this phenomenology to radiation from shock interaction with extended, dense material surrounding the progenitor star at r<10^15^cm and the resulting cooling emission. We calculate a total CSM mass of ~7x10^-3^M_{sun}_ (M_He_/M_H_~6) with particle density n~10^9^cm^-3^. Radio observations indicate a significantly lower density n<10^4^cm^-3^ at larger radii r>(0.1-1)x10^17^cm. The photometric and spectroscopic properties during the second light-curve peak are consistent with those of Ca-rich transients (rise-time of t_r_=13.4!+/-0.210days and a peak B-band magnitude of M_B_=-15.1+/-0.200mag). We find that SN 2019ehk synthesized (3.1+/-0.11)x10^-2^M_{sun}_ of ^56^Ni and ejected M_ej_=(0.72+/-0.040)M_{sun}_ total with a kinetic energy E_k_=(1.8+/-0.10)x10^50^erg. Finally, deep HST pre-explosion imaging at the SN site constrains the parameter space of viable stellar progenitors to massive stars in the lowest mass bin (~10M_{sun}_) in binaries that lost most of their He envelope or white dwarfs (WDs). The explosion and environment properties of SN 2019ehk further restrict the potential WD progenitor systems to low-mass hybrid HeCO WD+CO WD binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/6
- Title:
- UV to visible-light observations of SN 2018fif
- Short Name:
- J/ApJ/902/6
- Date:
- 25 Feb 2022 11:02:29
- Publisher:
- CDS
- Description:
- High-cadence transient surveys are able to capture supernovae closer to their first light than ever before. Applying analytical models to such early emission, we can constrain the progenitor stars' properties. In this paper, we present observations of SN 2018fif (ZTF18abokyfk). The supernova was discovered close to first light and monitored by the Zwicky Transient Facility (ZTF) and the Neil Gehrels Swift Observatory. Early spectroscopic observations suggest that the progenitor of SN 2018fif was surrounded by relatively small amounts of circumstellar material compared to all previous cases. This particularity, coupled with the high-cadence multiple-band coverage, makes it a good candidate to investigate using shock-cooling models. We employ the SOPRANOS code, an implementation of the model by Sapir & Waxman and its extension to early times by Morag et al. Compared with previous implementations, SOPRANOS has the advantage of including a careful account of the limited temporal validity domain of the shock-cooling model as well as allowing usage of the entirety of the early UV data. We find that the progenitor of SN 2018fif was a large red supergiant with a radius of R=744.0_-128.0_^+183.0^R_{sun}_ and an ejected mass of M_ej_=9.3_-5.8_^+0.4^M_{sun}_. Our model also gives information on the explosion epoch, the progenitor's inner structure, the shock velocity, and the extinction. The distribution of radii is double- peaked, with smaller radii corresponding to lower values of the extinction, earlier recombination times, and a better match to the early UV data. If these correlations persist in future objects, denser spectroscopic monitoring constraining the time of recombination, as well as accurate UV observations (e.g., with ULTRASAT), will help break the extinction/radius degeneracy and independently determine both.
- ID:
- ivo://CDS.VizieR/J/ApJ/664/1033
- Title:
- Variations in supernova yields
- Short Name:
- J/ApJ/664/1033
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Theoretical nucleosynthetic yields from supernovae are sensitive to both the details of the progenitor star and the explosion calculation. We attempt to comprehensively identify the sources of uncertainties in these yields. In this paper we concentrate on the variations in yields from a single progenitor arising from common 1D methods of approximating a supernova explosion. Subsequent papers will examine 3D effects in the explosion and the progenitor, and trends in mass and composition. For the 1D explosions we find that both elemental and isotopic yields for Si and heavier elements are a sensitive function of explosion energy. Also, piston-driven and thermal bomb-type explosions have different yields for the same explosion energy. Yields derived from 1D explosions are nonunique.
- 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.
- ID:
- ivo://CDS.VizieR/J/MNRAS/384/107
- Title:
- VRIJHK photometry of SN 2002cv
- Short Name:
- J/MNRAS/384/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present VRIJHK photometry, and optical and near-infrared spectroscopy, of the heavily extinguished Type Ia supernova (SN Ia) 2002cv, located in NGC 3190, which is also the parent galaxy of the SN Ia 2002bo. SN 2002cv, not visible in the blue, has a total visual extinction of 8.74+/-0.21mag. In spite of this, we were able to obtain the light curves between 10 and +207d from the maximum in the I band, and also to follow the spectral evolution, deriving its key parameters. We found the peak I-band brightness to be I_max_=16.57+/-0.10mag, the maximum absolute I magnitude to be M_max_I=18.79+/-0.20, and the parameter {delta}m15(B) specifying the width of the B-band light curve to be 1.46+/-0.17mag. The latter was derived using the relations between this parameter and {delta}m40(I) and the time-interval {delta}t_max_(I) between the two maxima in the I-band light curve. As has been found for previously observed, highly extinguished SNe Ia, a small value of 1.59+/-0.07 was obtained here for the ratio RV of the total-to-selective extinction ratio for SN 2002cv, which implies a small mean size for the grains along the line of sight towards us. Since it was found for SN 2002bo a canonical value of 3.1, here we present a clear evidence of different dust properties inside NGC 3190.
- 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.
