48 research outputs found
Optical observations of the fast declining type Ib supernova iPTF13bvn
We present optical UBVRI photometry and medium resolution spectroscopy of the
type Ib supernova iPTF13bvn, spanning a phase of d to d
with respect to -band maximum. The post maximum decline rates indicate a
fast decline with . Correcting for a galactic
extinction and host galaxy extinction of
, the absolute -band magnitude peaks at
M. The bolometric light curve indicates that M of Ni was synthesized in the explosion. The earliest
spectrum (d) shows the presence of He~{\sc i} 5876 \AA\ feature at a
velocity of 15000 km s, which falls rapidly by the time the SN
approaches the epoch of B-band maximum. The photospheric velocity near maximum
light, as indicated by the Fe~{\sc ii} 5169~\AA\ feature, is km
s. The estimate for the Ni mass, together with the estimates for
the ejected mass () and kinetic energy of the explosion
() indicate that iPTF13bvn is a low luminosity type Ib supernova,
with a lower than average ejected mass and kinetic energy. Our results suggest
that the progenitor of iPTF13bvn is inconsistent with a single Wolf-Rayet star.Comment: Accepted for publication in MNRAS, 11 pages, 12 figure
Multiparton Cwebs at five loops
Scattering amplitudes involving multiple partons are plagued with infrared
singularities. The soft singularities of the amplitude are captured by the soft
function which is defined as the vacuum expectation value of Wilson line
correlators. Renormalization properties of soft function allows us to write it
as an exponential of the finite soft anomalous dimension. An efficient way to
study the soft function is through a set of Feynman diagrams known as Cwebs
(webs). We obtain the mixing matrices and exponentiated colour factors for all
the Cwebs at five loops that connect six massless Wilson lines. Our results are
the first key ingredient for the calculation of the soft anomalous dimension at
five loops.Comment: 46 pages, 29 figures, 27 tables and 1 ancillary fil
iPTF13bvn: The First Evidence of a Binary Progenitor for a Type Ib Supernova
The recent detection in archival HST images of an object at the the location
of supernova (SN) iPTF13bvn may represent the first direct evidence of the
progenitor of a Type Ib SN. The object's photometry was found to be compatible
with a Wolf-Rayet pre-SN star mass of ~11 Msun. However, based on
hydrodynamical models we show that the progenitor had a pre-SN mass of ~3.5
Msun and that it could not be larger than ~8 Msun. We propose an interacting
binary system as the SN progenitor and perform evolutionary calculations that
are able to self-consistently explain the light-curve shape, the absence of
hydrogen, and the pre-SN photometry. We further discuss the range of allowed
binary systems and predict that the remaining companion is a luminous O-type
star of significantly lower flux in the optical than the pre-SN object. A
future detection of such star may be possible and would provide the first
robust identification of a progenitor system for a Type Ib SN.Comment: Accepted to AJ on July 26. Slight changes from original, however
delayed by slow refereeing proces
Multi-wavelength observations of multiple eruptions of the recurrent nova M31N 2008-12a
We report the optical, UV, and soft X-ray observations of the
eruptions of the recurrent nova M31N 2008-12a. We infer a steady decrease in
the accretion rate over the years based on the inter-eruption recurrence
period. We find a ``cusp'' feature in the and band light curves close
to the peak, which could be associated to jets. Spectral modelling indicates a
mass ejection of 10 to 10 M during each eruption, and
an enhanced Helium abundance of He/He 3. The super-soft
source (SSS) phase shows significant variability, which is anti-correlated to
the UV emission, indicating a common origin. The variability could be due to
the reformation of the accretion disk. A comparison of the accretion rate with
different models on the plane yields the mass of a CO
WD, powering the ``H-shell flashes'' every 1 year to be
M and growing with time, making M31N 2008-12a a strong candidate for
the single degenerate scenario of Type Ia supernovae progenitor.Comment: Submitted to AJ, 22 pages, 14 figures, 5 table
Multiwavelength Observations of Multiple Eruptions of the Recurrent Nova M31N 2008-12a
We report the optical, UV, and soft X-ray observations of the 2017–2022 eruptions of the recurrent nova M31N 2008-12a. We find a cusp feature in the r′ - and i′ -band light curves close to the peak, which could be related to jets. The geometry of the nova ejecta based on morpho-kinematic modeling of the Hα emission line indicates an extended jet-like bipolar structure. Spectral modeling indicates an ejecta mass of 10−7–10−8 M ⊙ during each eruption and an enhanced helium abundance. The supersoft source phase shows significant variability, which is anticorrelated to the UV emission, indicating a common origin. The variability could be due to the reformation of the accretion disk. We infer a steady decrease in the accretion rate over the years based on the intereruption recurrence period. A comparison of the accretion rate with different models on the MWD–Ṁ plane yields the mass of a CO white dwarf, powering the H-shell flashes every ∼1 yr, to be >1.36 M ⊙ and growing with time, making M31N 2008-12a a strong candidate for the single degenerate scenario of the Type Ia supernovae progenitor
The luminous type Ia supernova 2022ilv and its early excess emission
We present observations and analysis of the host-less and luminous type Ia
supernova 2022ilv, illustrating it is part of the 2003fg-like family, often
referred to as super-Chandrasekhar (Ia-SC) explosions. The ATLAS light curve
shows evidence of a short-lived, pulse-like early excess, similar to that
detected in another luminous type Ia supernova (SN 2020hvf). The light curve is
broad and the early spectra are remarkably similar to SN 2009dc. Adopting a
redshift of for SN 2022ilv based on spectral matching, our
model light curve requires a large Ni mass in the range
M, and a large ejecta mass in the range M. The
early excess can be explained by fast-moving SN ejecta interacting with a thin,
dense shell of circumstellar material close to the progenitor (
cm), a few hours after the explosion. This may be realised in a
double-degenerate scenario, wherein a white dwarf merger is preceded by
ejection of a small amount ( M) of hydrogen and
helium-poor tidally stripped material. A deep pre-explosion Pan-STARRS1 stack
indicates no host galaxy to a limiting magnitude of . This implies
a surprisingly faint limit for any host of , providing further
evidence that these types of explosion occur predominantly in low-metallicity
environments.Comment: Accepted to ApJL after minor revisio
SN 2020udy: A new piece of the homogeneous bright group in the diverse Iax subclass
We present optical observations and analysis of a bright type Iax SN~2020udy
hosted by NGC 0812. The light curve evolution of SN~2020udy is similar to other
bright Iax SNe. Analytical modeling of the quasi bolometric light curves of SN
2020udy suggests that 0.080.01 M of Ni would have been
synthesized during the explosion. Spectral features of SN 2020udy are similar
to the bright members of type Iax class showing weak Si {\sc II} line. The
late-time spectral sequence is mostly dominated by Iron Group Elements (IGEs)
with broad emission lines. Abundance tomography modeling of the spectral time
series of SN~2020udy using TARDIS indicates stratification in the outer ejecta,
however, to confirm this, spectral modeling at a very early phase is required.
After maximum light, uniform mixing of chemical elements is sufficient to
explain the spectral evolution. Unlike the case of normal type Ia SNe, the
photospheric approximation remains robust until +100 days, requiring an
additional continuum source. Overall, the observational features of SN 2020udy
are consistent with the deflagration of a Carbon-Oxygen white dwarf.Comment: 18 pages, 17 figures, 3 tables, Accepted for publication in Ap
Unprecedented early flux excess in the hybrid 02es-like type Ia supernova 2022ywc indicates interaction with circumstellar material
We present optical photometric and spectroscopic observations of the
02es-like type Ia supernova (SN) 2022ywc. The transient occurred in the
outskirts of an elliptical host galaxy and showed a striking double-peaked
light curve with an early excess feature detected in the ATLAS orange and cyan
bands. The early excess is remarkably luminous with an absolute magnitude , comparable in luminosity to the subsequent radioactively-driven second
peak. The spectra resemble the hybrid 02es-like SN 2016jhr, that is considered
to be a helium shell detonation candidate. We investigate different physical
mechanisms that could power such a prominent early excess and rule out massive
helium shell detonation, surface Ni distribution and ejecta-companion
interaction. We conclude that SN ejecta interacting with circumstellar material
(CSM) is the most viable scenario. Semi-analytical modelling with MOSFiT
indicates that SN ejecta interacting with M of CSM at a
distance of cm can explain the extraordinary light curve. A
double-degenerate scenario may explain the origin of the CSM, either by
tidally-stripped material from the secondary white dwarf, or disk-originated
matter launched along polar axes following the disruption and accretion of the
secondary white dwarf. A non-spherical CSM configuration could suggest that a
small fraction of 02es-like events viewed along a favourable line of sight may
be expected to display a very conspicuous early excess like SN 2022ywc.Comment: Accepted to ApJL after minor revisio