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ASASSN-15nx: A luminous Type II supernova with a 'perfect' linear decline
- Source :
- Astrophysical Journal, Artículos CONICYT, CONICYT Chile, instacron:CONICYT
- Publication Year :
- 2018
-
Abstract
- We report a luminous Type II supernova, ASASSN-15nx, with a peak luminosity of M_V=-20 mag, that is between typical core-collapse supernovae and super-luminous supernovae. The post-peak optical light curves show a long, linear decline with a steep slope of 2.5 mag/100 days (i.e., an exponential decline in flux), through the end of observations at phase ~260 days. In contrast, the light curves of hydrogen rich supernovae (SNe II-P/L) always show breaks in their light curves at phase ~100 days, before settling onto Co56 radioactive decay tails with a decline rate of about 1 mag/100 days. The spectra of ASASSN-15nx do not exhibit the narrow emission-line features characteristic of Type IIn SNe, which can have a wide variety of light-curve shapes usually attributed to strong interactions with a dense circumstellar medium (CSM). ASASSN-15nx has a number of spectroscopic peculiarities, including a relatively weak and triangularly-shaped H-alpha emission profile with no absorption component. The physical origin of these peculiarities is unclear, but the long and linear post-peak light curve without a break suggests a single dominant powering mechanism. Decay of a large amount of Ni56 (M_Ni56 = 1.6 +/- 0.2 M_sun) can power the light curve of ASASSN-15nx, and the steep light-curve slope requires substantial gamma-ray escape from the ejecta, which is possible given a low-mass hydrogen envelope for the progenitor. Another possibility is strong CSM interactions powering the light curve, but the CSM needs to be sculpted to produce the unique light-curve shape and to avoid producing SN IIn-like narrow emission lines.<br />Accepted for publication in ApJ. Ancillary ASCII tables added: photsn.txt -- photometry; L.txt -- blackbody bolometric luminosity
- Subjects :
- Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
7. Clean energy
01 natural sciences
Spectral line
Luminosity
0103 physical sciences
Astrophysics::Solar and Stellar Astrophysics
Emission spectrum
Exponential decay
010303 astronomy & astrophysics
Solar and Stellar Astrophysics (astro-ph.SR)
QC
Astrophysics::Galaxy Astrophysics
QB
Physics
High Energy Astrophysical Phenomena (astro-ph.HE)
010308 nuclear & particles physics
Astronomy and Astrophysics
Type II supernova
Light curve
Supernova
Astrophysics - Solar and Stellar Astrophysics
13. Climate action
Space and Planetary Science
Astrophysics - High Energy Astrophysical Phenomena
Radioactive decay
Subjects
Details
- Language :
- English
- ISSN :
- 00046256
- Database :
- OpenAIRE
- Journal :
- Astrophysical Journal, Artículos CONICYT, CONICYT Chile, instacron:CONICYT
- Accession number :
- edsair.doi.dedup.....6a8df66c73346bf7dcaf75883f2a014f