| 1. |
- Fiore, Achille, et al.
(author)
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Detailed spectrophotometric analysis of the superluminous and fast evolving SN 2019neq
- 2024
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In: Monthly notices of the Royal Astronomical Society. - 0035-8711 .- 1365-2966. ; 527:3, s. 6473-6494
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Journal article (peer-reviewed)abstract
- SN 2019neq was a very fast evolving superluminous supernova. At a redshift z = 0.1059, its peak absolute magnitude was −21.5 ± 0.2 mag in g band. In this work, we present data and analysis from an extensive spectrophotometric follow-up campaign using multiple observational facilities. Thanks to a nebular spectrum of SN 2019neq, we investigated some of the properties of the host galaxy at the location of SN 2019neq and found that its metallicity and specific star formation rate are in a good agreement with those usually measured for SLSNe-I hosts. We then discuss the plausibility of the magnetar and the circumstellar interaction scenarios to explain the observed light curves, and interpret a nebular spectrum of SN 2019neq using published SUMO radiative-transfer models. The results of our analysis suggest that the spin-down radiation of a millisecond magnetar with a magnetic field B ≃ 6×1014 G could boost the luminosity of SN 2019neq.
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| 2. |
- Bersten, Melina C., et al.
(author)
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THE TYPE IIb SUPERNOVA 2011dh FROM A SUPERGIANT PROGENITOR
- 2012
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In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 757:1
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Journal article (peer-reviewed)abstract
- A set of hydrodynamical models based on stellar evolutionary progenitors is used to study the nature of SN 2011dh. Our modeling suggests that a large progenitor star-with R similar to 200 R-circle dot-is needed to reproduce the early light curve (LC) of SN 2011dh. This is consistent with the suggestion that the yellow super-giant star detected at the location of the supernova (SN) in deep pre-explosion images is the progenitor star. From the main peak of the bolometric LC and expansion velocities, we constrain the mass of the ejecta to be approximate to 2 M-circle dot, the explosion energy to be E = (6-10) x 10(50) erg, and the Ni-56 mass to be approximately 0.06 M-circle dot. The progenitor star was composed of a helium core of 3-4 M-circle dot and a thin hydrogen-rich envelope of approximate to 0.1M(circle dot) with a main-sequence mass estimated to be in the range of 12-15 M-circle dot. Our models rule out progenitors with helium-core masses larger than 8 M-circle dot, which correspond to M-ZAMS greater than or similar to 25M(circle dot). This suggests that a single star evolutionary scenario for SN 2011dh is unlikely.
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| 3. |
- Bose, Subhash, et al.
(author)
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Gaia17biu/SN 2017egm in NGC 3191 : The Closest Hydrogen-poor Superluminous Supernova to Date Is in a Normal, Massive, Metal-rich Spiral Galaxy
- 2018
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 853:1
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Journal article (peer-reviewed)abstract
- Hydrogen-poor superluminous supernovae (SLSNe-I) have been predominantly found in low-metallicity, star-forming dwarf galaxies. Here we identify Gaia17biu/SN 2017egm as an SLSN-I occurring in a normal spiral galaxy (NGC 3191) in terms of stellar mass (several times 10(10) M-circle dot) and metallicity (roughly solar). At redshift z = 0.031, Gaia17biu is also the lowest-redshift SLSN-I to date, and the absence of a larger population of SLSNe-I in dwarf galaxies of similar redshift suggests that metallicity is likely less important to the production of SLSNe-I than previously believed. With the smallest distance and highest apparent brightness for an SLSN-I, we are able to study Gaia17biu in unprecedented detail. Its pre-peak near-ultraviolet to optical color is similar to that of Gaia16apd and among the bluest observed for an SLSN-I, while its peak luminosity (M-g = -21 mag) is substantially lower than that of Gaia16apd. Thanks to the high signal-to-noise ratios of our spectra, we identify several new spectroscopic features that may help to probe the properties of these enigmatic explosions. We detect polarization at the similar to 0.5% level that is not strongly dependent on wavelength, suggesting a modest, global departure from spherical symmetry. In addition, we put the tightest upper limit yet on the radio luminosity of an SLSN-I with < 5.4 x 10(26) erg s(-1) Hz(-1) at 10 GHz, which is almost a factor of 40 better than previous upper limits and one of the few measured at an early stage in the evolution of an SLSN-I. This limit largely rules out an association of this SLSN-I with known populations of gamma-ray-burst-like central engines.
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| 4. |
- Li, Wenxiong, et al.
(author)
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Observations of Type Ia Supernova 2014J for Nearly 900 Days and Constraints on Its Progenitor System
- 2019
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 882:1
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Journal article (peer-reviewed)abstract
- We present extensive ground-based and Hubble Space Telescope (HST) photometry of the highly reddened, very nearby SN Ia 2014J in M82, covering the phases from 9 days before to about 900 days after the B-band maximum. SN 2014J is similar to other normal SNe Ia near the maximum light, but it shows flux excess in the B band in the early nebular phase. This excess flux emission can be due to light scattering by some structures of circum stellar materials located at a few 10(17) cm, consistent with a single-degenerate progenitor system or a double-degenerate progenitor system with mass outflows in the final evolution or magnetically driven winds around the binary system. At t similar to +300 to similar to +500 days past the B-band maximum, the light curve of SN 2014J shows a faster decline relative to the Ni-56 decay. That feature can be attributed to the significant weakening of the emission features around [Fe III] lambda 4700 and [Fe II] lambda 5200 rather than the positron escape, as previously suggested. Analysis of the HST images taken at t > 600 days confirms that the luminosity of SN 2014J maintains a flat evolution at the very late phase. Fitting the late-time pseudobolometric light curve with radioactive decay of Ni-56, Ni-57, and Fe-55 isotopes, we obtain the mass ratio Ni-57/Ni-56 as 0.035 +/- 0.011, which is consistent with the corresponding value predicted from the 2D and 3D delayed-detonation models. Combined with early-time analysis, we propose that delayed detonation through the single-degenerate scenario is most likely favored for SN 2014J.
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| 5. |
- Zhang, Tianmeng, et al.
(author)
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Observations of a Fast-expanding and UV-bright Type Ia Supernova SN 2013gs
- 2019
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In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 872:1
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Journal article (peer-reviewed)abstract
- In this paper, we present extensive optical and ultraviolet (UV) observations of the type Ia supernova (SN Ia) 2013gs discovered during the Tsinghua-NAOC Transient Survey. The photometric observations in the optical show that the light curves of SN 2013gs are similar to those of normal SNe Ia, with an absolute peak magnitude of M-B = -19.25 +/- 0.15 mag and a post-maximum decline rate Delta m(15)(B) = 1.00 +/- 0.05 mag. Gehrels Swift Ultr-Violet/Optical Telescope observations indicate that SN 2013gs shows unusually strong UV emission (especially in the uvw1 band) at around the maximum light (M-uvw1 similar to -18.9 mag). The SN is characterized by relatively weak Fe II III absorptions at similar to 5000 angstrom in the early spectra and a larger expansion velocity (v(Si) similar to 13,000 km s(-1) around the maximum light) than the normal-velocity SNe Ia. We discuss the relation between the uvw1 - v color and some observables, including Si II velocity, line strength of Si II lambda 6355 and Fe II/III lines, and Delta m(15)(B). Compared to other fast-expanding SNe Ia, SN 2013gs exhibits Si and Fe absorption lines with similar strength and bluer uvw1 - v color. We briefly discussed the origin of the observed UV dispersion of SNe Ia.
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