282 research outputs found
Is there a hidden hole in Type Ia supernova remnants?
In this paper we report on the bulk features of the hole carved by the
companion star in the material ejected during a Type Ia supernova explosion. In
particular we are interested in the long term evolution of the hole as well as
in its fingerprint in the geometry of the supernova remnant after several
centuries of evolution, which is a hot topic in current Type Iasupernovae
studies. We use an axisymmetric smoothed particle hydrodynamics code to
characterize the geometric properties of the supernova remnant resulting from
the interaction of this ejected material with the ambient medium. Our aim is to
use supernova remnant observations to constrain the single degenerate scenario
for Type Ia supernova progenitors. Our simulations show that the hole will
remain open during centuries, although its partial or total closure at later
times due to hydrodynamic instabilities is not excluded. Close to the edge of
the hole, the Rayleigh-Taylor instability grows faster, leading to plumes that
approach the edge of the forward shock. We also discuss other geometrical
properties of the simulations, like the evolution of the contact discontinuity.Comment: 48 pages, 17 figures; Accepted for publication in Ap
An X-Ray Study of Supernova Remnant N49 and Soft Gamma-Ray Repeater 0526-66 in the Large Magellanic Cloud
We report on the results from our deep Chandra observation (120 ks) of the
supernova remnant (SNR) N49 and soft Gamma-ray repeater (SGR) 0526-66 in the
Large Magellanic Cloud. We firmly establish the detection of an ejecta "bullet"
beyond the southwestern boundary of N49. The X-ray spectrum of the bullet is
distinguished from that of the main SNR shell, showing significantly enhanced
Si and S abundances. We also detect an ejecta feature in the eastern shell,
which shows metal overabundances similar to those of the bullet. If N49 was
produced by a core-collapse explosion of a massive star, the detected Si-rich
ejecta may represent explosive O-burning or incomplete Si-burning products from
deep interior of the supernova. On the other hand, the observed Si/S abundance
ratio in the ejecta may favor Type Ia origin for N49. We refine the Sedov age
of N49, tau_Sed ~ 4800 yr, with the explosion energy E_0 ~ 1.8 x 10^51 erg. Our
blackbody (BB) + power law (PL) model for the quiescent X-ray emission from SGR
0526-66 indicates that the PL photon index (Gamma ~ 2.5) is identical to that
of PSR 1E1048.1-5937, the well-known candidate transition object between
anomalous X-ray pulsars and SGRs. Alternatively, the two-component BB model
implies X-ray emission from a small (R ~ 1 km) hot spot(s) (kT ~ 1 keV) in
addition to emission from the neutron star's cooler surface (R ~ 10 km, kT ~
0.4 keV). There is a considerable discrepancy in the estimated column toward
0526-66 between BB+PL and BB+BB model fits. Discriminating these spectral
models would be crucial to test the long-debated physical association between
N49 and 0526-66.Comment: Accepted by ApJ, 27 pages in total (aastex preprint format) including
5 figures (4 in color) and 5 table
A Super-Solar Metallicity for the Progenitor of Kepler's Supernova
We have performed deep X-ray observations of the remnant of Kepler's
supernova (SN 1604) as a Key Project of the Suzaku Observatory. Our main goal
is to detect secondary Fe-peak elements in the SN ejecta to gain insights into
the Type Ia supernova explosion mechanism and the nature of the progenitor.
Here we report our initial results. We made a conclusive detection of X-ray
emission lines from highly ionized Mn, Cr, and Ni as well as Fe. The observed
Mn-to-Cr line flux ratio is ~0.60, ~30% larger than that measured in Tycho's
remnant. We estimate a Mn-to-Cr mass ratio of ~0.77, which is strongly
suggestive of a large neutron excess in the progenitor star before the onset of
the thermonuclear runaway. The observed Ni-to-Fe line flux ratio (~0.03)
corresponds to a mass ratio of ~0.06, which is generally consistent with the
products of explosive Si-burning regime in Type Ia explosion models, and rules
out contamination from the products of neutron-rich nuclear statistical
equilibrium in the shocked ejecta. Together with the previously suggested
luminous nature of the explosion, these mass ratios provide strong evidence for
a super-solar metallicity in the SN progenitor (~3 Z_sun). Kepler's supernova
was likely the thermonuclear explosion of a white dwarf formed in the recent
past that must have exploded through a relatively prompt channel.Comment: Total 12 pages including 2 tables and 2 color figures. Accepted by
ApJ
Are the Models for Type Ia Supernova Progenitors Consistent with the Properties of Supernova Remnants?
We explore the relationship between the models for progenitor systems of Type
Ia supernovae and the properties of the supernova remnants that evolve after
the explosion. Most models for Type Ia progenitors in the single degenerate
scenario predict substantial outflows during the presupernova evolution.
Expanding on previous work, we estimate the imprint of these outflows on the
structure of the circumstellar medium at the time of the supernova explosion,
and the effect that this modified circumstellar medium has on the evolution of
the ensuing supernova remnant. We compare our simulations with the
observational properties of known Type Ia supernova remnants in the Galaxy
(Kepler, Tycho, SN 1006), the Large Magellanic Cloud (0509-67.5, 0519-69.0,
N103B), and M31 (SN 1885). We find that optically thick outflows from the white
dwarf surface (sometimes known as accretion winds) with velocities above 200
km/s excavate large low-density cavities around the progenitors. Such large
cavities are incompatible with the dynamics of the forward shock and the X-ray
emission from the shocked ejecta in all the Type Ia remnants that we have
examined.Comment: To appear in ApJ. 17 pages, 10 figures, emulateap
Supernova Remnants as Clues to Their Progenitors
Supernovae shape the interstellar medium, chemically enrich their host
galaxies, and generate powerful interstellar shocks that drive future
generations of star formation. The shock produced by a supernova event acts as
a type of time machine, probing the mass loss history of the progenitor system
back to ages of 10 000 years before the explosion, whereas supernova
remnants probe a much earlier stage of stellar evolution, interacting with
material expelled during the progenitor's much earlier evolution. In this
chapter we will review how observations of supernova remnants allow us to infer
fundamental properties of the progenitor system. We will provide detailed
examples of how bulk characteristics of a remnant, such as its chemical
composition and dynamics, allow us to infer properties of the progenitor
evolution. In the latter half of this chapter, we will show how this exercise
may be extended from individual objects to SNR as classes of objects, and how
there are clear bifurcations in the dynamics and spectral characteristics of
core collapse and thermonuclear supernova remnants. We will finish the chapter
by touching on recent advances in the modeling of massive stars, and the
implications for observable properties of supernovae and their remnants.Comment: A chapter in "Handbook of Supernovae" edited by Athem W. Alsabti and
Paul Murdin (18 pages, 6 figures
The Imprint of Presupernova Evolution on Supernovae Remnants
The evolution of type Ia supernova binary system progenitors is highly
uncertain. Several evolutionary models predict that the accretion of mass onto
the white dwarf is accompanied by mass ejection from the binary in the form of
a powerful wind, but very few observations have been made during the initial
phase of formation of supernovae remnants, when the interaction of supernova
ejecta with presupernova wind could be tested. Here we present hydrodynamical
simulations of supernova ejecta interaction with an ambient medium modified by
presupernova wind. The structure of the ambient medium when the supernova
explodes is very sensitive to the details of wind history, and the evolution of
the supernova remnant can be affected during several thousand years. We have
found that the forward shock expansion parameter is a good tool for
discriminating between several wind models. The evolution of the supernova
remnant in the presence of an ambient medium modified by interaction with
pre-supernova wind cannot be described by a similarity solution. We also rule
out simple models based on a circumstellar medium that merges smoothly with a
uniform density ambient medium.Comment: 18 pages, 5 figures, to be published in ApJ
The metal contents of two groups of galaxies
The hot gas in clusters and groups of galaxies is continuously being enriched
with metals from supernovae and stars. It is well established that the
enrichment of the gas with elements from oxygen to iron is mainly caused by
supernova explosions. The origins of nitrogen and carbon are still being
debated. Possible candidates include massive, metal-rich stars, early
generations of massive stars, intermediate or low mass stars and Asymptotic
Giant Branch (AGB) stars. In this paper we accurately determine the metal
abundances of the gas in the groups of galaxies NGC 5044 and NGC 5813, and
discuss the nature of the objects that create these metals.
We mainly focus on carbon and nitrogen. We use spatially-resolved
high-resolution X-ray spectroscopy from XMM-Newton. For the spectral fitting,
multi-temperature hot gas models are used. The abundance ratios of carbon over
oxygen and nitrogen over oxygen that we find are high compared to the ratios in
the stars in the disk of our Galaxy. The oxygen and nitrogen abundances we
derive are similar to what was found in earlier work on other giant ellipticals
in comparable environments. We show that the iron abundances in both our
sources have a gradient along the cross-dispersion direction of the Reflection
Grating Spectrometer (RGS). We conclude that it is unlikely that the creation
of nitrogen and carbon takes place in massive stars, which end their lives as
core-collapse supernovae, enriching the medium with oxygen because oxygen
should then also be enhanced. Therefore we favour low-and intermediate mass
stars as sources of these elements. The abundances in the hot gas can best be
explained by a 30-40% contribution of type Ia supernovae based on the measured
oxygen and iron abundances and under the assumption of a Salpeter Initial Mass
Function (IMF).Comment: Accepted for publication in A&A, 12 pages, 10 figures. Data points on
which figs 4,5,8 and 9 are based are present as comment in the source fil
Observations of SN2011fe with INTEGRAL
SN2011fe was detected by the Palomar Transient Factory on August 24th 2011 in
M101 few hours after the explosion. From the early spectra it was immediately
realized that it was a Type Ia supernova thus making this event the brightest
one discovered in the last twenty years. In this paper the observations
performed with the instruments on board of INTEGRAL (SPI, IBIS/ISGRI, JEM-X and
OMC) before and after the maximum of the optical light as well as the
interpretation in terms of the existing models of --ray emission from
such kind of supernovae are reported. All INTEGRAL high-energy have only been
able to provide upper limits to the expected emission due to the decay of
Ni. These bounds allow to reject explosions involving a massive white
dwarf in the sub--Chandrasekhar scenario. On the other hand, the optical light
curve obtained with the OMC camera suggests that the event was produced by a
delayed detonation of a CO white dwarf that produced M of
Ni. In this particular case, INTEGRAL would have only been able to
detect the early --ray emission if the supernova had occurred at a
distance of 2 -3 Mpc, although the brightest event could be visible up to
distances larger by a factor two.Comment: Proceedings of "An INTEGRAL view of the high-energy sky (the first 10
years)" the 9th INTEGRAL Workshop, October 15-19, 2012, Paris, France, in
Proceedings of Science (INTEGRAL 2012), Eds. A. Goldwurm, F. Lebrun and C.
Winkler, http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=176, id number
PoS (INTEGRAL 2012) 103 (2013
Observation of SN2011fe with INTEGRAL. I. Pre--maximum phase
SN2011fe was detected by the Palomar Transient Factory on August 24th 2011 in
M101 a few hours after the explosion. From the early optical spectra it was
immediately realized that it was a Type Ia supernova thus making this event the
brightest one discovered in the last twenty years. The distance of the event
offered the rare opportunity to perform a detailed observation with the
instruments on board of INTEGRAL to detect the gamma-ray emission expected from
the decay chains of Ni. The observations were performed in two runs, one
before and around the optical maximum, aimed to detect the early emission from
the decay of Ni and another after this maximum aimed to detect the
emission of Co. The observations performed with the instruments on board
of INTEGRAL (SPI, IBIS/ISGRI, JEMX and OMC) have been analyzed and compared
with the existing models of gamma-ray emission from such kind of supernovae. In
this paper, the analysis of the gamma-ray emission has been restricted to the
first epoch. Both, SPI and IBIS/ISGRI, only provide upper-limits to the
expected emission due to the decay of Ni. These upper-limits on the
gamma-ray flux are of 7.1 10 ph/s/cm for the 158 keV line
and of 2.3 10 ph/s/cm for the 812 keV line. These bounds
allow to reject at the level explosions involving a massive white
dwarf, M in the sub--Chandrasekhar scenario and specifically
all models that would have substantial amounts of radioactive Ni in the
outer layers of the exploding star responsible of the SN2011fe event. The
optical light curve obtained with the OMC camera also suggests that SN2011fe
was the outcome of the explosion, possibly a delayed detonation although other
models are possible, of a CO white dwarf that synthesized M
of Ni. For this specific model.Comment: Accepted for publication in A&A. 10 pages, 10 figure
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