51 research outputs found
Detection and classification of supernovae beyond z~2 redshift with the James Webb Space Telescope
Future time-domain surveys for transient events in the near- and mid-infrared
bands will significantly extend our understanding about the physics of the
early Universe. In this paper we study the implications of a deep (~27 mag),
long-term (~3 years), observationally inexpensive survey with the James Webb
Space Telescope (JWST) within its Continuous Viewing Zone, aimed at discovering
luminous supernovae beyond z~2 redshift. We explore the possibilities for
detecting Superluminous Supernovae (SLSNe) as well as Type Ia supernovae at
such high redshifts and estimate their expected numbers within a relatively
small (~0.1 deg^2) survey area. It is found that we can expect ~10 new SLSNe
and ~50 SNe Ia discovered in the 1 < z < 4 redshift range. We show that it is
possible to get relatively accurate (sigma_z < 0.25) photometric redshifts for
Type Ia SNe by fitting their Spectral Energy Distributions (SED), redshifted
into the observed near-IR bands, with SN templates. We propose that Type Ia SNe
occupy a relatively narrow range on the JWST F220W-F440W vs F150W-F356W
color-color diagram between +/- 7 rest-frame days around maximum light, which
could be a useful classification tool for such type of transients. We also
study the possibility of extending the Hubble-diagram of Type Ia SNe beyond
redshift 2 up to z~4. Such high-z SNe Ia may provide new observational
constraints for their progenitor scenario.Comment: accepted for publication in Ap
Distance estimate and progenitor characteristics of SN 2005cs in M51
Distance to the Whirlpool Galaxy (M51, NGC 5194) is estimated using published
photometry and spectroscopy of the Type II-P supernova SN 2005cs. Both the
Expanding Photosphere Method (EPM) and the Standard Candle Method (SCM),
suitable for SNe II-P, were applied. The average distance (7.1 \pm 1.2 Mpc) is
in good agreement with earlier SBF- and PNLF-based distances, but slightly
longer than the distance obtained by Baron et al. for SN 1994I via the Spectral
Fitting Expanding Atmosphere Method (SEAM). Since SN 2005cs exhibited low
expansion velocity during the plateau phase, similarly to SN 1999br, the
constants of SCM were re-calibrated including the data of SN 2005cs as well.
The new relation is better constrained in the low velocity regime (v_{ph}(50) ~
1500 - 2000$ km/s), that may result in better distance estimates for such SNe.
The physical parameters of SN 2005cs and its progenitor are re-evaluated based
on the updated distance. All the available data support the low-mass (~ 9
M_\odot) progenitor scenario proposed previously by its direct detection with
the Hubble Space Telescope.Comment: 7 pages, 4 figures, 4 tables, accepted in MNRA
Detecting Pair-Instability Supernovae at z<5 with the James Webb Space Telescope
Pair-instability supernovae (PISNe) are the ultimate cosmic lighthouses,
capable of being observed at z<25 and revealing the properties of primordial
stars at cosmic dawn. But it is now understood that the spectra and light
curves of these events evolved with redshift as the universe became polluted
with heavy elements because chemically enriched stars in this mass range
typically lose most of their hydrogen envelopes and explode as bare helium
cores. The light curves of such transients can be considerably dimmer in the
near infrared (NIR) today than those of primordial PISNe of equal energy and
progenitor mass. Here, we calculate detection rates for PISNe whose progenitors
lost their outer layers to either line-driven winds or rotation at z<10, their
detection limit in redshift for the James Webb Space Telescope (JWST). We find
that JWST may be able to detect only Pop II (metal-poor) PISNe over the
redshift range of z<4, but not their Pop III (metal-free) counterparts.Comment: Accepted for ApJ, in pres
A semi-analytical light curve model and its application to type IIP supernovae
The aim of this work is to present a semi-analytical light curve modeling
code which can be used for estimating physical properties of core collapse
supernovae (SNe) in a quick and efficient way. To verify our code we fit light
curves of Type II SNe and compare our best parameter estimates to those from
hydrodynamical calculations. For this analysis we use the quasi-bolometric
light curves of five different Type IIP supernovae. In each case we get
appropriate results for the initial pre-supernova parameters. We conclude that
this semi-analytical light curve model is useful to get approximate physical
properties of Type II SNe without using time-consuming numerical hydrodynamic
simulations.Comment: accepted for publication in Astronomy \& Astrophysics; corrected
Fig.2, 3,
Lost in space: companions' fatal dance around massive dying stars
Discoveries of planet- and stellar remnant-hosting pulsars challenge our
understanding as the violent supernova explosion that forms the pulsar
presumably destabilizes the system. Type II supernova explosions lead to the
formation of eccentric bound systems, free-floating planets, neutron stars,
pulsars, and white dwarfs. Analytical and numerical studies of high mass-loss
rate systems based on perturbation theory so far have focused mainly on
planet-star systems. In this paper, we extend our understanding of the fate of
planet-star and binary systems by assuming a homologous envelope expansion
model using a plausible ejection velocity (),
envelope- and neutron star masses. The investigation covers secondary masses of
1-10MJup for planetary, and 1-20MSun for stellar companions. We conduct and
analyze over 2.5 million simulations assuming different semi-major axes (2.23 -
100au), eccentricities (0-0.8), and true-anomalies (0-2pi) for the companion.
In a homologous expansion scenario, we confirm that the most probable outcome
of the explosion is the destabilization of the system, while the retention of a
bound system requires a highly eccentric primordial orbit. In general, a higher
ejecta velocity results in a lower eccentricity orbit independent of secondary
mass. The explanation of close-in pulsar planets requires exotic formation
scenarios, rather than survival through the type II supernova explosion model.
Post-explosion bound star systems gain a peculiar velocity (<100\,km/s), even
though the explosion model is symmetric. The applied numerical model allows us
to derive velocity components for dissociating systems. The peculiar velocities
of free-floating planets and stellar corpses are in the range of 10^-6-275km/s.Comment: Accepted for publication in ApJ (proofread
Possible detection of singly-ionized oxygen in the Type Ia SN 2010kg
We present direct spectroscopic modeling of 11 high-S/N observed spectra of
the Type Ia SN 2010kg, taken between -10 and +5 days with respect to B-maximum.
The synthetic spectra, calculated with the SYN++ code, span the range between
4100 and 8500 \r{A}. Our results are in good agreement with previous findings
for other Type Ia SNe. Most of the spectral features are formed at or close to
the photosphere, but some ions, like Fe II and Mg II, also form features at
~2000 - 5000 km s above the photosphere. The well-known high-velocity
features of the Ca II IR-triplet as well as Si II 6355 are also
detected.
The single absorption feature at ~4400 \r{A}, which usually has been
identified as due to Si III, is poorly fit with Si III in SN 2010kg. We find
that the fit can be improved by assuming that this feature is due to either C
III or O II, located in the outermost part of the ejecta, ~4000 - 5000 km
s above the photosphere. Since the presence of C III is unlikely,
because of the lack of the necessary excitation/ionization conditions in the
outer ejecta, we identify this feature as due to O II. The simultaneous
presence of O I and O II is in good agreement with the optical depth
calculations and the temperature distribution in the ejecta of SN 2010kg. This
could be the first identification of singly ionized oxygen in a Type Ia SN
atmosphere.Comment: Submitted to MNRA
High-Velocity Features of Calcium and Silicon in the Spectra of Type Ia Supernovae
"High-velocity features" (HVFs) are spectral features in Type Ia supernovae
(SNe Ia) that have minima indicating significantly higher (by greater than
about 6000 km/s) velocities than typical "photospheric-velocity features"
(PVFs). The PVFs are absorption features with minima indicating typical
photospheric (i.e., bulk ejecta) velocities (usually ~9000-15,000 km/s near
B-band maximum brightness). In this work we undertake the most in-depth study
of HVFs ever performed. The dataset used herein consists of 445 low-resolution
optical and near-infrared (NIR) spectra (at epochs up to 5 d past maximum
brightness) of 210 low-redshift SNe Ia that follow the "Phillips relation." A
series of Gaussian functions is fit to the data in order to characterise
possible HVFs of Ca II H&K, Si II {\lambda}6355, and the Ca II NIR triplet. The
temporal evolution of the velocities and strengths of the PVFs and HVFs of
these three spectral features is investigated, as are possible correlations
with other SN Ia observables. We find that while HVFs of Ca II are regularly
observed (except in underluminous SNe Ia, where they are never found), HVFs of
Si II {\lambda}6355 are significantly rarer, and they tend to exist at the
earliest epochs and mostly in objects with large photospheric velocities. It is
also shown that stronger HVFs of Si II {\lambda}6355 are found in objects that
lack C II absorption at early times and that have red ultraviolet/optical
colours near maximum brightness. These results lead to a self-consistent
connection between the presence and strength of HVFs of Si II {\lambda}6355 and
many other mutually correlated SN~Ia observables, including photospheric
velocity.Comment: 48 pages (22 of which are tables), 15 figures, 5 tables, re-submitted
to MNRAS (after first referee report
The Exceptionally Luminous Type Ia Supernova 2007If
SN 2007if was the third over-luminous Type Ia supernova (SN Ia) detected after 2003fg and 2006gz. We present the photometric and spectroscopic observations of the SN and its host by ROTSE-III, HET, and Keck. From the H a line identified in the host spectra, we determine a redshift of 0.0736. At this distance, the SN reached an absolute magnitude of -20.4, brighter than any other SNe Ia ever observed. If the source of luminosity is radioactive decay, a large amount of radioactive nickel (similar to 1.5 M(circle dot)) is required to power the peak luminosity, more than can be produced realistically in a Chandrasekhar mass progenitor. Low expansion velocity, similar to that of 2003fg, is also measured around the maximum light. The observations may suggest that SN 2007if was from a massive white dwarf progenitor, plausibly exploding with mass well beyond 1.4 M(circle dot). Alternatively, we investigate circumstellar interaction that may contribute to the excess luminosity.NASA NNX-08AN25G, NNX-08AV63GNSF AST-0707769, PHY-0801007Australian Research CouncilUniversity of New South WalesUniversity of TexasUniversity of MichiganAstronom
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