SN 2015bq: A Luminous Type Ia Supernova with Early Flux Excess

Abstract We present optical and ultraviolet (UV) observations of a luminous type Ia supernova (SN Ia) SN 2015bq characterized by early flux excess. This SN reaches a B-band absolute magnitude at M B = −19.68 ± 0.41 mag and a peak bolometric luminosity at L = (1.75 ± 0.37) × 1043 erg s−1, with a relatively small post-maximum decline rate [Δm 15(B) = 0.82 ± 0.05 mag]. The flux excess observed in the light curves of SN 2015bq a few days after the explosion, especially seen in the UV bands, might be due to the radioactive decay of 56Ni mixed into the surface. The radiation from the decay of the surface 56Ni heats the outer layer of this SN. It produces blue U − B color followed by monotonically reddening in the early phase, dominated iron-group lines, and weak intermediate-mass element absorption features in the early spectra. The scenario of enhanced 56Ni in the surface is consistent with a large amount of 56Ni ( M 56 Ni = 0.97 ± 0.20 M ☉) synthesized during the explosion. The properties of SN 2015bq are found to locate between SN 1991T and SN 1999aa, suggesting the latter two subclasses of SNe Ia may have a common origin.

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Rapidly Declining Hostless Type Ia Supernova KSP-OT-201509b from the KMTNet Supernova Program: Transitional Nature and Constraint on 56Ni Distribution and Progenitor Type

The Astrophysical Journal ◽

10.3847/1538-4357/abe466 ◽

2021 ◽

Vol 910 (2) ◽

pp. 151

Author(s):

Dae-Sik Moon ◽

Yuan Qi Ni ◽

Maria R. Drout ◽

Santiago González-Gaitán ◽

Niloufar Afsariardchi ◽

...

Keyword(s):

Light Curve ◽

Radioactive Decay ◽

Light Curves ◽

Host Galaxy ◽

Curve Evolution ◽

Sensitivity Limit ◽

Bolometric Luminosity ◽

Type Ia Supernova ◽

Type Ia ◽

High Cadence

Abstract We report the early discovery and multicolor (BVI) high-cadence light-curve analyses of the rapidly declining sub-Chandrasekhar Type Ia supernova KSP-OT-201509b (= AT 2015cx) from the KMTNet Supernova Program. The Phillips and color stretch parameters of KSP-OT-201509b are ΔM B,15 ≃ 1.62 mag and s BV ≃ 0.54, respectively, at an inferred redshift of 0.072. These, together with other measured parameters (such as the strength of the secondary I-band peak, colors, and luminosity), identify the source to be a rapidly declining Type Ia of a transitional nature that is closer to Branch-normal than 91bg-like. Its early light-curve evolution and bolometric luminosity are consistent with those of homologously expanding ejecta powered by radioactive decay and a Type Ia SN explosion with 0.32 ± 0.01 M ⊙ of synthesized 56Ni mass, 0.84 ± 0.12 M ⊙ of ejecta mass, and (0.61 ± 0.14) × 1051 erg of ejecta kinetic energy. While its B − V and V − I colors evolve largely synchronously with the changes in the I-band light curve, as found in other supernovae, we also find the presence of an early redward evolution in V − I prior to −10 days since peak. The bolometric light curve of the source is compatible with a stratified 56Ni distribution extended to shallow layers of the exploding progenitor. Comparisons between the observed light curves and those predicted from ejecta–companion interactions clearly disfavor Roche lobe–filling companion stars at large separation distances, thus supporting a double-degenerate scenario for its origin. The lack of any apparent host galaxy in our deep stack images reaching a sensitivity limit of ∼28 mag arcsec−2 makes KSP-OT-201509b a hostless Type Ia supernova and offers new insights into supernova host galaxy environments.

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Highly reddened Type Ia supernova SN 2004ab: another case of anomalous extinction

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx2839 ◽

2017 ◽

Vol 474 (2) ◽

pp. 2502-2513 ◽

Cited By ~ 1

Author(s):

N K Chakradhari ◽

D K Sahu ◽

G C Anupama ◽

T P Prabhu

Keyword(s):

Velocity Gradient ◽

Spectroscopic Data ◽

Absolute Magnitude ◽

Host Galaxy ◽

Broad Line ◽

Rate Parameter ◽

Bolometric Luminosity ◽

Type Ia Supernova ◽

Type Ia ◽

Anomalous Extinction

Abstract We present optical photometric and spectroscopic data for supernova SN 2004ab, a highly reddened normal Type Ia supernova. The total reddening is estimated as E(B − V) = 1.70 ± 0.05 mag. The intrinsic decline-rate parameter Δm15(B)true is 1.27 ± 0.05, and the B-band absolute magnitude at maximum $M_{B}^{{\rm max}}$ is −19.31 ± 0.25 mag. The host galaxy NGC 5054 is found to exhibit anomalous extinction with a very low value of RV = 1.41 ± 0.06 in the direction of SN 2004ab. The peak bolometric luminosity is derived as $\log L_{\rm bol}^{\rm max}$ = 43.10 ± 0.07 erg s−1. The photospheric velocity measured from the absorption minimum of the Si ii λ6355 line shows a velocity gradient of $\dot{v}$ = 90 km s−1 d−1, indicating that SN 2004ab is a member of the high velocity gradient (HVG) subgroup. The ratio of the strengths of the Si ii λ5972 and λ6355 absorption lines, $\cal R$(Si ii), is estimated as 0.37, while their pseudo-equivalent widths suggest that SN 2004ab belongs to the broad line (BL) type subgroup.

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Light-curve properties of SN 2017fgc and HV SNe Ia

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab254 ◽

2021 ◽

Vol 502 (3) ◽

pp. 4112-4124

Author(s):

Umut Burgaz ◽

Keiichi Maeda ◽

Belinda Kalomeni ◽

Miho Kawabata ◽

Masayuki Yamanaka ◽

...

Keyword(s):

Light Curve ◽

Near Infrared ◽

Light Curves ◽

Normal Velocity ◽

External Effects ◽

Band Maximum ◽

Bolometric Luminosity ◽

V Band ◽

Photometric And Spectroscopic Observations ◽

Type Ia

ABSTRACT Photometric and spectroscopic observations of Type Ia supernova (SN) 2017fgc, which cover the period from −12 to + 137 d since the B-band maximum are presented. SN 2017fgc is a photometrically normal SN Ia with the luminosity decline rate, Δm15(B)true = 1.10 ± 0.10 mag. Spectroscopically, it belongs to the high-velocity (HV) SNe Ia group, with the Si ii λ6355 velocity near the B-band maximum estimated to be 15 200 ± 480 km s−1. At the epochs around the near-infrared secondary peak, the R and I bands show an excess of ∼0.2-mag level compared to the light curves of the normal velocity (NV) SNe Ia. Further inspection of the samples of HV and NV SNe Ia indicates that the excess is a generic feature among HV SNe Ia, different from NV SNe Ia. There is also a hint that the excess is seen in the V band, both in SN 2017fgc and other HV SNe Ia, which behaves like a less prominent shoulder in the light curve. The excess is not obvious in the B band (and unknown in the U band), and the colour is consistent with the fiducial SN colour. This might indicate that the excess is attributed to the bolometric luminosity, not in the colour. This excess is less likely caused by external effects, like an echo or change in reddening but could be due to an ionization effect, which reflects an intrinsic, either distinct or continuous, difference in the ejecta properties between HV and NV SNe Ia.

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Supernova Abundance Generation

Symposium - International Astronomical Union ◽

10.1017/s007418090022723x ◽

1991 ◽

Vol 145 ◽

pp. 21-38

Author(s):

K. Nomoto ◽

T. Shigeyama ◽

T. Tsujimoto

Keyword(s):

Heavy Element ◽

Massive Stars ◽

Theoretical Models ◽

Light Curves ◽

Maximum Brightness ◽

Sn 1987A ◽

New Models ◽

Decline Rate ◽

Type Ia ◽

Supernova Explosions

Theoretical models of supernova explosions of various types are reviewed to obtain heavy element yields from supernovae. We focus on new models for SN 1987A, and Type Ia, Ib, and Ic supernovae. Maximum brightness and decline rate of their light curves suggest that 12–18 M⊙ stars produce larger amount of 56Ni than more massive stars. We discuss relative roles of various types of supernovae in the chemical evolution of galaxies.

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Think Global, Act Local: The Influence of Environment Age and Host Mass on Type Ia Supernova Light Curves

The Astrophysical Journal ◽

10.3847/1538-4357/ab0704 ◽

2019 ◽

Vol 874 (1) ◽

pp. 32 ◽

Cited By ~ 16

Author(s):

B. M. Rose ◽

P. M. Garnavich ◽

M. A. Berg

Keyword(s):

Light Curves ◽

Type Ia Supernova ◽

Type Ia

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Using gamma ray monitoring to avoid missing the next Milky Way Type Ia supernova

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz993 ◽

2019 ◽

Vol 486 (2) ◽

pp. 2910-2918 ◽

Cited By ~ 2

Author(s):

Xilu Wang (王夕露) ◽

Brian D Fields ◽

Amy Yarleen Lien (連雅琳)

Keyword(s):

Gamma Rays ◽

Milky Way ◽

Gamma Ray ◽

Galactic Plane ◽

Early Warning Systems ◽

Light Curves ◽

X Rays ◽

Warning Systems ◽

Type Ia Supernova ◽

Type Ia

Abstract A Milky Way Type Ia supernova (SNIa) could be unidentified or even initially unnoticed, being dim in radio, X-rays, and neutrinos, and suffering large optical/IR extinction in the Galactic plane. But SNIa emit nuclear gamma-ray lines from 56Ni → 56Co → 56Fe radioactive decays. These lines fall within the Fermi/GBM energy range, and the 56Ni 158 keV line is detectable by Swift/BAT. Both instruments frequently monitor the Galactic plane, which is transparent to gamma rays. Thus GBM and BAT are ideal Galactic SNIa early warning systems. We simulate SNIa MeV light curves and spectra to show that GBM and BAT could confirm a Galactic SNIa explosion, followed by Swift localization and observation in X-rays and UVOIR band. The time of detection depends sensitively on the 56Ni distribution, and can be as early as a few days if ${\gtrsim } 10{{\ \rm per\ cent}}$ of the 56Ni is present in the surface as suggested by SN2014J gamma data.

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Theoretical Light Curves for Type Ia Supernovae and Determination of the Hubble Constant

Symposium - International Astronomical Union ◽

10.1017/s0074180900132139 ◽

1999 ◽

Vol 183 ◽

pp. 68-68

Author(s):

Koichi Iwamoto ◽

Ken'Ichi Nomoto

Keyword(s):

Hubble Constant ◽

Light Curves ◽

Type Ia Supernovae ◽

Maximum Brightness ◽

Decline Rate ◽

Type Ia ◽

Error Bars ◽

Ia Supernovae ◽

Distance Indicators

The large luminosity (MV ≈ −19 ∼ −20) and the homogeneity in light curves and spectra of Type Ia supernovae(SNe Ia) have led to their use as distance indicators ultimately to determine the Hubble constant (H0). However, an increasing number of the observed samples from intermediate- and high-z (z ∼ 0.1 − 1) SN Ia survey projects(Hamuy et al. 1996, Perlmutter et al. 1997) have shown that there is a significant dispersion in the maximum brightness (∼ 0.4 mag) and the brighter-slower correlation between the brightness and the postmaximum decline rate, which was first pointed out by Phillips(1993). By taking the correlation into account, Hamuy et al.(1996) gave an estimate of H0 within the error bars half as much as previous ones.

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Cosmological Inference from Host-Selected Type Ia Supernova Samples

Publications of the Astronomical Society of Australia ◽

10.1017/pasa.2017.2 ◽

2017 ◽

Vol 34 ◽

Cited By ~ 3

Author(s):

Syed A. Uddin ◽

Jeremy Mould ◽

Chris Lidman ◽

Vanina Ruhlmann-Kleider ◽

Delphine Hardin

Keyword(s):

Dark Energy ◽

Equation Of State ◽

Real Time ◽

Matter Density ◽

Light Curves ◽

Type Ia Supernova ◽

Type Ia

AbstractWe compare two Type Ia supernova samples that are drawn from a spectroscopically confirmed Type Ia supernova sample: a host-selected sample in which SNe Ia are restricted to those that have a spectroscopic redshift from the host; and a broader, more traditional sample in which the redshift could come from either the SN or the host. The host-selected sample is representative of SN samples that will use the redshift of the host to infer the SN redshift, long after the SN has faded from view. We find that SNe Ia that are selected on the availability of a redshift from the host differ from SNe Ia that are from the broader sample. The former tend to be redder, have narrower light curves, live in more massive hosts, and tend to be at lower redshifts. We find that constraints on the equation of state of dark energy, w, and the matter density, ΩM, remain consistent between these two types of samples. Our results are important for ongoing and future supernova surveys, which unlike previous supernova surveys, will have limited real-time follow-up to spectroscopically classify the SNe they discover. Most of the redshifts in these surveys will come from the hosts.

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