12 research outputs found
Optical Signatures of Circumstellar Interaction in Type IIP Supernovae
We propose new diagnostics for circumstellar interaction in Type IIP
supernovae by the detection of high velocity (HV) absorption features in Halpha
and He I 10830 A lines during the photospheric stage. To demonstrate the
method, we compute the ionization and excitation of H and He in supernova
ejecta taking into account time-dependent effects and X-ray irradiation. We
find that the interaction with a typical red supergiant wind should result in
the enhanced excitation of the outer layers of unshocked ejecta and the
emergence of corresponding HV absorption, i.e. a depression in the blue
absorption wing of Halpha and a pronounced absorption of He I 10830 A at a
radial velocity of about -10,000 km/s. We identify HV absorption in Halpha and
He I 10830 A lines of SN 1999em and in Halpha of SN 2004dj as being due to this
effect. The derived mass loss rate is close to 10^{-6} Msun/yr for both
supernovae, assuming a wind velocity 10 km/s. We argue that, in addition to the
HV absorption formed in the unshocked ejecta, spectra of SN 2004dj and SN
1999em show a HV notch feature that is formed in the cool dense shell (CDS)
modified by the Rayleigh-Taylor instability. The CDS results from both shock
breakout and radiative cooling of gas that has passed through the reverse shock
wave. The notch becomes dominant in the HV absorption during the late
photospheric phase, ~60 d. The wind density deduced from the velocity of the
CDS is consistent with the wind density found from the HV absorption produced
by unshocked ejecta.Comment: 38 pages, 12 figures, ApJ, in pres
The spectacular evolution of Supernova 1996al over 15 years: a low energy explosion of a stripped massive star in a highly structured environment
Spectrophotometry of SN 1996al carried out throughout 15 years is presented.
The early photometry suggests that SN 1996al is a Linear type-II supernova,
with an absolute peak of Mv ~ -18.2 mag. Early spectra present broad,
asymmetric Balmer emissions, with super-imposed narrow lines with P-Cygni
profile, and He I features with asymmetric, broad emission components. The
analysis of the line profiles shows that the H and He broad components form in
the same region of the ejecta. By day +142, the Halpha profile dramatically
changes: the narrow P-Cygni profile disappears, and the Halpha is fitted by
three emission components, that will be detected over the remaining 15 yrs of
the SN monitoring campaign. Instead, the He I emissions become progressively
narrower and symmetric. A sudden increase in flux of all He I lines is observed
between 300 and 600 days. Models show that the supernova luminosity is
sustained by the interaction of low mass (~1.15 Msun) ejecta, expelled in a low
kinetic energy (~ 1.6 x 10^50 erg) explosion, with highly asymmetric
circumstellar medium. The detection of Halpha emission in pre-explosion archive
images suggests that the progenitor was most likely a massive star (~25 Msun
ZAMS) that had lost a large fraction of its hydrogen envelope before explosion,
and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest
kinetic energy of the explosion are explained with massive fallback of material
into the compact remnant, a 7-8 Msun black hole.Comment: 27 pages, 23 figures, Accepted for publication in MNRA
StaNdaRT: A repository of standardized test models and outputs for supernova radiative transfer
Accepted for publication in A&A. 26 pages, 12 figures. The ejecta models and output files from the simulations are available at https://github.com/sn-rad-trans/data1International audienceWe present the first results of a comprehensive supernova (SN) radiative-transfer (RT) code-comparison initiative (StaNdaRT), where the emission from the same set of standardized test models is simulated by currently-used RT codes. A total of ten codes have been run on a set of four benchmark ejecta models of Type Ia supernovae. We consider two sub-Chandrasekhar-mass ( M) toy models with analytic density and composition profiles and two Chandrasekhar-mass delayed-detonation models that are outcomes of hydrodynamical simulations. We adopt spherical symmetry for all four models. The results of the different codes, including the light curves, spectra, and the evolution of several physical properties as a function of radius and time, are provided in electronic form in a standard format via a public repository. We also include the detailed test model profiles and several python scripts for accessing and presenting the input and output files. We also provide the code used to generate the toy models studied here. In this paper, we describe in detail the test models, radiative-transfer codes and output formats and provide access to the repository. We present example results of several key diagnostic features
StaNdaRT: A repository of standardized test models and outputs for supernova radiative transfer
Accepted for publication in A&A. 26 pages, 12 figures. The ejecta models and output files from the simulations are available at https://github.com/sn-rad-trans/data1International audienceWe present the first results of a comprehensive supernova (SN) radiative-transfer (RT) code-comparison initiative (StaNdaRT), where the emission from the same set of standardized test models is simulated by currently-used RT codes. A total of ten codes have been run on a set of four benchmark ejecta models of Type Ia supernovae. We consider two sub-Chandrasekhar-mass ( M) toy models with analytic density and composition profiles and two Chandrasekhar-mass delayed-detonation models that are outcomes of hydrodynamical simulations. We adopt spherical symmetry for all four models. The results of the different codes, including the light curves, spectra, and the evolution of several physical properties as a function of radius and time, are provided in electronic form in a standard format via a public repository. We also include the detailed test model profiles and several python scripts for accessing and presenting the input and output files. We also provide the code used to generate the toy models studied here. In this paper, we describe in detail the test models, radiative-transfer codes and output formats and provide access to the repository. We present example results of several key diagnostic features