20 research outputs found
Evolution of the progenitors of SNe 1993J and 2011dh revealed through late time radio and X-ray studies
We perform hydrodynamical simulations of the interaction between supernova
(SN) ejecta and circumstellar medium (CSM) for SN 1993J and SN 2011dh, and
calculate the radio and X-ray emissions expected from the shocked gas at late
epochs (). Considering the ejecta structure from multi-group radiation
hydrodynamics simulation, we find that the observed rapid drop in radio and
X-ray light curves of SN 1993J at 3000 days can be due to a change in the
mass-loss rate () around 6500 years prior to the explosion of the
SN. The exact epoch scales inversely with the assumed wind velocity of . The progenitor of this SN very likely belonged to a binary
system, where, during its evolution, the primary had transferred material to
the secondary. It is argued in the paper that the change in can happen
because of a change in the mass accretion efficiency () of the companion
star. It is possible that before years
prior to the explosion, was high, thus the CSM was tenuous, which causes
the late time downturn in fluxes. In the case of SN 2011dh, the late time
evolution is found to be consistent with a wind medium with . It is difficult from
our analysis to predict whether the progenitor of this SN had a binary
companion, however, if future observations show similar decrease in radio and
X-ray fluxes, then that would give strong support to a scenario where both SNe
had undergone similar kind of binary evolution before explosion.Comment: 13 pages, 10 figures; Accepted for publication in Ap
The progenitor mass of the Type IIP supernova SN 2004et from late-time spectral modeling
SN 2004et is one of the nearest and best-observed Type IIP supernovae, with a
progenitor detection as well as good photometric and spectroscopic
observational coverage well into the nebular phase. Based on nucleosynthesis
from stellar evolution/explosion models we apply spectral modeling to analyze
its 140-700 day evolution from ultraviolet to mid-infrared. We find a M_ZAMS=
15 Msun progenitor star (with an oxygen mass of 0.8 Msun) to satisfactorily
reproduce [O I] 6300, 6364 {\AA} and other emission lines of carbon, sodium,
magnesium, and silicon, while 12 Msun and 19 Msun models under- and overproduce
most of these lines, respectively. This result is in fair agreement with the
mass derived from the progenitor detection, but in disagreement with
hydrodynamical modeling of the early-time light curve. From modeling of the
mid-infrared iron-group emission lines, we determine the density of the
"Ni-bubble" to rho(t) = 7E-14*(t/100d)^-3 g cm^-3, corresponding to a filling
factor of f = 0.15 in the metal core region (V = 1800 km/s). We also confirm
that silicate dust, CO, and SiO emission are all present in the spectra.Comment: 21 pages, 15 figures. Accepted for publication in A&
High Density Circumstellar Interaction in the Luminous Type IIn SN 2010jl: The first 1100 days
HST and ground based observations of the Type IIn SN 2010jl are analyzed,
including photometry, spectroscopy in the ultraviolet, optical and NIR bands,
26-1128 days after first detection. At maximum the bolometric luminosity was
erg/s and even at 850 days exceeds erg/s. A NIR
excess, dominating after 400 days, probably originates in dust in the
circumstellar medium (CSM). The total radiated energy is
ergs, excluding the dust component. The spectral lines can be separated into
one broad component due to electron scattering, and one narrow with expansion
velocity km/s from the CSM. The broad component is initially
symmetric around zero velocity but becomes blueshifted after days,
while remaining symmetric about a shifted centroid velocity. Dust absorption in
the ejecta is unlikely to explain the line shifts, and we attribute the shift
instead to acceleration by the SN radiation. From the optical lines and the
X-ray and dust properties, there is strong evidence for large scale asymmetries
in the CSM. The ultraviolet lines indicate CNO processing in the progenitor,
while the optical shows a number of narrow coronal lines excited by the X-rays.
The bolometric light curve is consistent with a radiative shock in an
CSM with a mass loss rate of M_sun/yr. The total mass lost is
M_sun. These properties are consistent with the SN expanding into a CSM
characteristic of an LBV progenitor with a bipolar geometry. The apparent
absence of nuclear processing is attributed to a CSM still opaque to electron
scattering.Comment: ApJ in press. Updated and changed after referees comment
Lightcurve and spectral modelling of the Type IIb SN 2020acat. Evidence for a strong Ni bubble effect on the diffusion time
We use the light curve and spectral synthesis code JEKYLL to calculate a set
of macroscopically mixed Type IIb supernova (SN) models, which are compared to
both previously published and new late-phase observations of SN 2020acat. The
models differ in the initial mass, the radial mixing and expansion of the
radioactive material, and the properties of the hydrogen envelope. The best
match to the photospheric and nebular spectra and lightcurves of SN 2020acat is
found for a model with an initial mass of 17 solar masses, strong radial mixing
and expansion of the radioactive material, and a 0.1 solar mass hydrogen
envelope with a low hydrogen mass-fraction of 0.27. The most interesting result
is that strong expansion of the clumps containing radioactive material seems to
be required to fit the observations of SN 2020acat both in the diffusion phase
and the nebular phase. These "Ni bubbles" are expected to expand due to heating
from radioactive decays, but the degree of expansion is poorly constrained.
Without strong expansion there is a tension between the diffusion phase and the
subsequent evolution, and models that fit the nebular phase produce a diffusion
peak that is too broad. The diffusion phase lightcurve is sensitive to the
expansion of the "Ni bubbles", as the resulting Swiss-cheese-like geometry
decreases the effective opacity and therefore the diffusion time. This effect
has not been taken into account in previous lightcurve modelling of
stripped-envelope SNe, which may lead to a systematic underestimate of their
ejecta masses. It should be emphasized, though, that JEKYLL is limited to a
geometry that is spherically symmetric on average, and large-scale asymmetries
may also play a role. The relatively high initial mass found for the progenitor
of SN 2020acat places it at the upper end of the mass distribution of Type IIb
SN progenitors, and a single star origin can not be excluded.Comment: Accepted for publication by Astronomy and Astrophysic
High-density circumstellar interaction in the luminous Type IIn SN 2010jl : the first 1100 days
Hubble Space Telescope and ground-based observations of the Type IIn supernova (SN) 2010jl are analyzed, including photometry and spectroscopy in the ultraviolet, optical, and near-IR bands, 26-1128 days after first detection. At maximum, the bolometric luminosity was ~3 × 1043 erg s-1 and even at 850 days exceeds 1042 erg s-1. A near-IR excess, dominating after 400 days, probably originates in dust in the circumstellar medium (CSM). The total radiated energy is >~ 6.5 × 1050 erg, excluding the dust component. The spectral lines can be separated into one broad component that is due to electron scattering and one narrow with expansion velocity ~100 km s-1 from the CSM. The broad component is initially symmetric around zero velocity but becomes blueshifted after ~50 days, while remaining symmetric about a shifted centroid velocity. Dust absorption in the ejecta is unlikely to explain the line shifts, and we attribute the shift instead to acceleration by the SN radiation. From the optical lines and the X-ray and dust properties, there is strong evidence for large-scale asymmetries in the CSM. The ultraviolet lines indicate CNO processing in the progenitor, while the optical shows a number of narrow coronal lines excited by the X-rays. The bolometric light curve is consistent with a radiative shock in an r-2 CSM with a mass-loss rate of Ṁ ∼ 0.1 M⊙ yr-1. The total mass lost is >~ 3 M⊙. These properties are consistent with the SN expanding into a CSM characteristic of a luminous blue variable progenitor with a bipolar geometry. The apparent absence of nuclear processing is attributed to a CSM that is still opaque to electron scattering.Peer reviewe
The type IIB supernova 2011DH from a supergiant progenitor
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 ∼ 200 R⊙ - 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 ≈2 M⊙, the explosion energy to be E = (6-10) × 1050 erg, and the 56NI mass to be approximately 0.06 M⊙. The progenitor star was composed of a helium core of 3-4 M⊙ and a thin hydrogen-rich envelope of ≈0.1M ⊙ with a main-sequence mass estimated to be in the range of 12-15 M⊙. Our models rule out progenitors with helium-core masses larger than 8 M⊙, which correspond to MZAMS ≳ 25M⊙. This suggests that a single star evolutionary scenario for SN 2011DH is unlikely.Facultad de Ciencias Astronómicas y GeofÃsica
The Type IIb Supernova 2011dh from a Supergiant Progenitor
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 ~200 Rsun---, is needed to reproduce the early light
curve of SN 2011dh. This is consistent with the suggestion that the yellow
super-giant star detected at the location of the SN in deep pre-explosion
images is the progenitor star. From the main peak of the bolometric light curve
and expansion velocities we constrain the mass of the ejecta to be ~2 Msun, the
explosion energy to be E= 6-10 x 10^50 erg, and the 56Ni mass to be
approximately 0.06 Msun. The progenitor star was composed of a helium core of 3
to 4 Msun and a thin hydrogen-rich envelope of ~0.1 M_sun with a main sequence
mass estimated to be in the range of 12--15 Msun. Our models rule out
progenitors with helium-core masses larger than 8 Msun, which correspond to
M_ZAMS > 25 Msun. This suggests that a single star evolutionary scenario for SN
2011dh is unlikely.Comment: 20 pages with 12 figures. Submitted to The Astrophysical Journal on
24 May 2012 and accepted on 17 July 201
Evidence for Late-stage Eruptive Mass Loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient
We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.4 ± 0.1 mag hr-1) and luminous (Mg,peak = -20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity (Lbol ≳ 3 × 1044 erg s-1), the short rise time (trise = 3 days in g band), and the blue colors at peak (g-r ∼ -0.4) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (Teff ≳ 40,000 K) spectra of a stripped-envelope SN. A retrospective search revealed luminous (Mg ∼ Mr ≈ mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray energy release E γ,iso \u3c 4.9 × 10 48 erg, a limit on X-ray emission LX \u3c 1040 erg s-1, and a limit on radio emission ν Lν ≲ 1037 erg s-1. Taken together, we find that the early (\u3c 10 days) data are best explained by shock breakout in a massive shell of dense circumstellar material (0.02 M⊙) at large radii (3 × 1014 cm) that was ejected in eruptive pre-explosion mass-loss episodes. The late-time (\u3e 10 days) light curve requires an additional energy source, which could be the radioactive decay of Ni-56
The Death Throes of a Stripped Massive Star: An Eruptive Mass-Loss History Encoded in Pre-Explosion Emission, a Rapidly Rising Luminous Transient, and a Broad-Lined Ic Supernova SN2018gep
We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.3 mag/hr) and luminous (M_(g,peak) = −20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The rapid rise to peak bolometric luminosity and blue colors at peak (t_(rise)∼0.5-3 days, L_(bol)≳3×10^(44) erg sec^(−1), g−r = −0.3) resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (T_(eff) ≳ 40,000K) spectra of a stripped-envelope SN. A retrospective search revealed luminous (M_g ∼ M_r ≈ −14mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray energy release E_(γ,iso) < 4.9×10^(48) erg, a limit on X-ray emission L_X < 10^(40) erg sec^(−1), and a limit on radio emission νL_ν ≲ 10^(37) erg sec^(−1). Taken together, we find that the data are best explained by shock breakout in a massive shell of dense circumstellar material (0.02 M⊙) at large radii (3×10^(14)cm) that was ejected in eruptive pre-explosion mass-loss episodes