11 research outputs found
DESI-253.2534+26.8843: A New Einstein Cross Spectroscopically Confirmed with VLT/MUSE and Modeled with GIGA-Lens
Gravitational lensing provides unique insights into astrophysics and
cosmology, including the determination of galaxy mass profiles and constraining
cosmological parameters. We present spectroscopic confirmation and lens
modeling of the strong lensing system DESI-253.2534+26.8843, discovered in the
Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys data. This
system consists of a massive elliptical galaxy surrounded by four blue images
forming an Einstein Cross pattern. We obtained spectroscopic observations of
this system using the Multi Unit Spectroscopic Explorer (MUSE) on ESO's Very
Large Telescope (VLT) and confirmed its lensing nature. The main lens, which is
the elliptical galaxy, has a redshift of , while the
spectra of the background source images are typical of a starburst galaxy and
have a redshift of . Additionally, we identified a faint
galaxy foreground of one of the lensed images, with a redshift of . We employed the GIGA-Lens modeling code to characterize this system and
determined the Einstein radius of the main lens to be , which corresponds to a velocity dispersion of
= 379 2 km s. Our study contributes to a growing catalog
of this rare kind of strong lensing systems and demonstrates the effectiveness
of spectroscopic integral field unit observations and advanced modeling
techniques in understanding the properties of these systems.Comment: Accepted for publication in ApJ
The fast declining Type Ia supernova 2003gs, and evidence for a significant dispersion in near-infrared absolute magnitudes of fast decliners at maximum light
We obtained optical photometry of SN 2003gs on 49 nights, from 2 to 494 days
after T(B_max). We also obtained near-IR photometry on 21 nights. SN 2003gs was
the first fast declining Type Ia SN that has been well observed since SN
1999by. While it was subluminous in optical bands compared to more slowly
declining Type Ia SNe, it was not subluminous at maximum light in the near-IR
bands. There appears to be a bimodal distribution in the near-IR absolute
magnitudes of Type Ia SNe at maximum light. Those that peak in the near-IR
after T(B_max) are subluminous in the all bands. Those that peak in the near-IR
prior to T(B_max), such as SN 2003gs, have effectively the same near-IR
absolute magnitudes at maximum light regardless of the decline rate Delta
m_15(B).
Near-IR spectral evidence suggests that opacities in the outer layers of SN
2003gs are reduced much earlier than for normal Type Ia SNe. That may allow
gamma rays that power the luminosity to escape more rapidly and accelerate the
decline rate. This conclusion is consistent with the photometric behavior of SN
2003gs in the IR, which indicates a faster than normal decline from
approximately normal peak brightness.Comment: 41 pages, 13 figures, to be published in the December, 2009, issue of
the Astronomical Journa
Near-Infrared and Optical Observations of Type Ic SN 2021krf: Luminous Late-time Emission and Dust Formation
We present near-infrared (NIR) and optical observations of the Type Ic
supernova (SN Ic) SN 2021krf obtained between days 13 and 259 at several
ground-based telescopes. The NIR spectrum at day 68 exhibits a rising -band
continuum flux density longward of 2.0 m, and a late-time optical
spectrum at day 259 shows strong [O I] 6300 and 6364 \r{A} emission-line
asymmetry, both indicating the presence of dust, likely formed in the SN
ejecta. We estimate a carbon-grain dust mass of 2 10
M and a dust temperature of 900 - 1200 K associated with this
rising continuum and suggest the dust has formed in SN ejecta. Utilizing the
one-dimensional multigroup radiation hydrodynamics code STELLA, we present two
degenerate progenitor solutions for SN 2021krf, characterized by C-O star
masses of 3.93 and 5.74 M, but with the same best-fit Ni mass
of 0.11 M for early times (0-70 days). At late times (70-300 days),
optical light curves of SN 2021krf decline substantially more slowly than that
expected from Co radioactive decay. Lack of H and He lines in the
late-time SN spectrum suggests the absence of significant interaction of the
ejecta with the circumstellar medium. We reproduce the entire bolometric light
curve with a combination of radioactive decay and an additional powering source
in the form of a central engine of a millisecond pulsar with a magnetic field
smaller than that of a typical magnetar.Comment: Accepted for publication in ApJ, 27 pages, 21 figures, 6 tables.
Previous arXiv submission (arXiv:2211.00205) replaced after acceptanc
SN 2019hcc: a Type II supernova displaying early O II lines
We present optical spectroscopy together with ultraviolet, optical, and near-infrared photometry of SN 2019hcc, which resides in a host galaxy at redshift 0.044, displaying a sub-solar metallicity. The supernova spectrum near peak epoch shows a 'w' shape at around 4000 Å which is usually associated with O II lines and is typical of Type I superluminous supernovae. SN 2019hcc post-peak spectra show a well-developed H α P-Cygni profile from 19 d past maximum and its light curve, in terms of its absolute peak luminosity and evolution, resembles that of a fast-declining Hydrogen-rich supernova (SN IIL). The object does not show any unambiguous sign of interaction as there is no evidence of narrow lines in the spectra or undulations in the light curve. Our TARDIS spectral modelling of the first spectrum shows that carbon, nitrogen, and oxygen (CNO) at 19 000 K reproduce the 'w' shape and suggests that a combination of non-thermally excited CNO and metal lines at 8000 K could reproduce the feature seen at 4000 Å. The Bolometric light-curve modelling reveals that SN 2019hcc could be fit with a magnetar model, showing a relatively strong magnetic field (B > 3 × 1014 G), which matches the peak luminosity and rise time without powering up the light curve to superluminous luminosities. The high-energy photons produced by the magnetar would then be responsible for the detected O II lines. As a consequence, SN 2019hcc shows that a 'w' shape profile at around 4000 Å, usually attributed to O II, is not only shown in superluminous supernovae and hence it should not be treated as the sole evidence of the belonging to such a supernova type...
SNÂ 2019hcc: a Type II supernova displaying early O ii lines
We present optical spectroscopy together with ultraviolet, optical, and near-infrared photometry of SN 2019hcc, which resides in a host galaxy at redshift 0.044, displaying a sub-solar metallicity. The supernova spectrum near peak epoch shows a ‘w’ shape at around 4000 Å which is usually associated with O ii lines and is typical of Type I superluminous supernovae. SN 2019hcc post-peak spectra show a well-developed H α P-Cygni profile from 19 d past maximum and its light curve, in terms of its absolute peak luminosity and evolution, resembles that of a fast-declining Hydrogen-rich supernova (SN IIL). The object does not show any unambiguous sign of interaction as there is no evidence of narrow lines in the spectra or undulations in the light curve. Our tardis spectral modelling of the first spectrum shows that carbon, nitrogen, and oxygen (CNO) at 19 000 K reproduce the ‘w’ shape and suggests that a combination of non-thermally excited CNO and metal lines at 8000 K could reproduce the feature seen at 4000 Å. The Bolometric light-curve modelling reveals that SN 2019hcc could be fit with a magnetar model, showing a relatively strong magnetic field (B > 3 × 1014 G), which matches the peak luminosity and rise time without powering up the light curve to superluminous luminosities. The high-energy photons produced by the magnetar would then be responsible for the detected O ii lines. As a consequence, SN 2019hcc shows that a ‘w’ shape profile at around 4000 Å, usually attributed to O ii, is not only shown in superluminous supernovae and hence it should not be treated as the sole evidence of the belonging to such a supernova type
SN 2019hcc: a Type II supernova displaying early O II lines
We present optical spectroscopy together with ultraviolet, optical and
near-infrared photometry of SN 2019hcc, which resides in a host galaxy at
redshift 0.044, displaying a sub-solar metallicity. The supernova spectrum near
peak epoch shows a `w' shape at around 4000 {\AA} which is usually associated
with O II lines and is typical of Type I superluminous supernovae. SN 2019hcc
post-peak spectra show a well-developed H alpha P-Cygni profile from 19 days
past maximum and its light curve, in terms of its absolute peak luminosity and
evolution, resembles that of a fast-declining Hydrogen-rich supernova (SN IIL).
The object does not show any unambiguous sign of interaction as there is no
evidence of narrow lines in the spectra or undulations in the light curve. Our
tardis spectral modelling of the first spectrum shows that Carbon, Nitrogen and
Oxygen (CNO) at 19000 K reproduce the `w' shape and suggests that a combination
of non-thermally excited CNO and metal lines at 8000 K could reproduce the
feature seen at 4000 {\AA}. The Bolometric light curve modelling reveals that
SN 2019hcc could be fit with a magnetar model, showing a relatively strong
magnetic field (B > 3 x 10^14 G), which matches the peak luminosity and rise
time without powering up the light curve to superluminous luminosities. The
high-energy photons produced by the magnetar would then be responsible for the
detected O II lines. As a consequence, SN 2019hcc shows that a `w' shape
profile at around 4000 {\AA}, usually attributed to O II, is not only shown in
superluminous supernovae and hence it should not be treated as the sole
evidence of the belonging to such a supernova type.Comment: Paper accepted on MNRAS, 24 pages, 18 figure