A5003803425- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Pulsars and Gravitational Waves Research
- Astrophysics and Star Formation Studies
- SAS software applications and methods
- Galaxies: Formation, Evolution, Phenomena
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Neutrino Physics Research
- Planetary Science and Exploration
- Adaptive optics and wavefront sensing
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Advanced Sensor and Energy Harvesting Materials
- High voltage insulation and dielectric phenomena
- Calibration and Measurement Techniques
- Scientific Research and Discoveries
- Magnetic Properties and Synthesis of Ferrites
- Electromagnetic wave absorption materials
- Spacecraft and Cryogenic Technologies
- Multiferroics and related materials
Indian Institute of Astrophysics
2016-2025
SRM Institute of Science and Technology
2025
National Institute of Technology Raipur
2024
Bundelkhand University
2010-2023
Ambedkar University Delhi
2023
Rashtrasant Tukadoji Maharaj Nagpur University
2018
Indian Institute of Technology Hyderabad
2015
Center for Study of Science Technology and Policy
2008
The University of Tokyo
2005-2007
Max Planck Institute for Astrophysics
2005-2007
Wide-field optical surveys have begun to uncover large samples of fast (trise ≲ 5 d), luminous (Mpeak < −18), blue transients. While commonly attributed the breakout a supernova shock into dense wind, great distances transients this class found so far hampered detailed investigation their properties. We present photometry and spectroscopy from comprehensive worldwide campaign observe AT 2018cow (ATLAS 18qqn), first fast-luminous transient be in real time at low redshift. Our spectra (<2 days...
Abstract We present early-phase panchromatic photometric and spectroscopic coverage spanning the far-ultraviolet to near-infrared regime of nearest hydrogen-rich core-collapse supernova (SN) in last 25 yr, SN 2023ixf. observe early “flash” features optical spectra due confined dense circumstellar material (CSM). high-ionization absorption lines (Fe ii , Mg ) ultraviolet from very on. also a multipeaked emission profile H α spectrum beginning at ∼16 days, which indicates ongoing interaction...
Abstract The unluckiest star orbits a supermassive black hole elliptically. Every time it reaches the pericenter, shallowly enters tidal radius and gets partially tidally disrupted, producing series of flares. Confirmation repeated partial disruption event (pTDE) requires not only evidence to rule out other types transients but also proof that one is involved, as TDEs from multiple stars can produce similar In this Letter, we report discovery pTDE, AT 2022dbl. quiescent galaxy at z = 0.0284,...
We present optical photometry and spectroscopy of the type IIP supernova SN 2004et that occurred in nearby galaxy NGC 6946.The observations span a time range 8 days to 541 after explosion.The late bolometric luminosity Hα nebular phase indicate 0.06 ± 0.02M ⊙ 56 Ni was synthesised during plateau luminosity, its duration expansion velocity at middle an explosion energy E exp = 1.20 +0.38 -0.30 × 10 51 ergs.The light curve evolution [OI] emission line profiles possibility early dust formation...
The recent detection in archival HST images of an object at the location supernova (SN) iPTF13bvn may represent first direct evidence progenitor a Type Ib SN. object's photometry was found to be compatible with Wolf-Rayet pre-SN star mass ~11 Msun. However, based on hydrodynamical models we show that had ~3.5 Msun and it could not larger than ~8 We propose interacting binary system as SN perform evolutionary calculations are able self-consistently explain light-curve shape, absence hydrogen,...
Supernova (SN) 2015bh (or SNhunt275) was discovered in NGC 2770 on 2015 February with an absolute magnitude of Mr ~ -13.4 mag, and initially classified as a SN impostor. Here we present the photometric spectroscopic evolution from discovery to late phases (~ 1 yr after). In addition, inspect archival images host galaxy up 21 before discovery, finding burst further signatures stellar instability until 2014. Later on, luminosity transient slowly increases, broad light curve peak is reached...
Abstract We present a detailed investigation of photometric, spectroscopic, and polarimetric observations the Type II SN 2023ixf. Earlier studies have provided compelling evidence for delayed shock breakout from confined dense circumstellar matter (CSM) enveloping progenitor star. The temporal evolution polarization in 2023ixf phase revealed three distinct peaks at 1.4 days, 6.4 79.2 indicating an asymmetric CSM, aspherical front clumpiness low-density extended inner ejecta/He-core....
Observations and modeling for the light curve (LC) spectra of supernova (SN) 2005bf are reported. This SN showed unique features: LC had two maxima, declined rapidly after second maximum, while strengthening He lines whose velocity increased with time. The double-peaked can be reproduced by a $^{56}$Ni distribution, most at low small amount high velocity. rapid post-maximum decline requires large fraction $γ$-rays to escape from $^{56}$Ni-dominated region, possibly because low-density...
$UBVRI$ photometry and medium resolution optical spectroscopy of peculiar Type Ia supernova SN 2005hk are presented analysed, covering the pre-maximum phase to around 400 days after explosion. The is found be underluminous compared "normal" supernovae. photometric spectroscopic evolution remarkably similar event 2002cx. expansion velocity ejecta lower than normal events. spectra obtained $\gsim 200$ since explosion do not show presence forbidden [\ion{Fe}{ii}], [\ion{Fe}{iii}]...
We present early-time optical and near-infrared photometry of supernova (SN) 2005cf. The observations, spanning a period from about 12 d before to 3 months after maximum, have been obtained through the coordination observational efforts various nodes European Supernova Collaboration including data at 2-m Himalayan Chandra Telescope. From observed light curve we deduce that SN 2005cf is fairly typical Ia with post-maximum decline [Δm15(B)true= 1.12] close average value normal luminosity...
We present a detailed study of the prompt and afterglow emission from Swift GRB 061126 using BAT, XRT, UVOT data multi-color optical imaging ten ground-based telescopes. was long burst (T_90=191 s) with four overlapping peaks in its gamma-ray light curve. The X-ray afterglow, observed 26 min to 20 days after burst, shows simple power-law decay alpha_X=1.290 \pm 0.008. Optical observations presented here cover time range 258 s (Faulkes Telescope North) 15 (Gemini burst; rate steep-to-shallow...
We present a theoretical model for supernova SN 2008D associated with the luminous X-ray transient 080109. The bolometric light curve and optical spectra of are modeled based on progenitor models explosion obtained from hydrodynamic/nucleosynthetic calculations. find that is more energetic than normal core-collapse supernovae, an ejecta mass Mej = 5.3 ± 1.0 M☉ kinetic energy EK 6.0 2.5 × 1051 erg. star has 6–8 He core essentially no H envelope (<5 10−4 M☉) prior to explosion. main-sequence...
We present ground-based and HST optical observations of the transients (OTs) long-duration Gamma Ray Bursts (GRBs) 060729 090618, both at a redshift z = 0.54. For GRB 060729, bumps are seen in light curves (LCs), late-time broadband spectral energy distributions (SEDs) OT resemble those local type Ic supernovae (SNe). dense sampling our has allowed us to detect well-defined LCs, as well change colour, that indicative coming from core-collapse SN. The accompanying SNe for events individually...
We present the low-resolution spectroscopic and UBVRI broad-band photometric investigations of Type IIb supernova 2011fu, discovered in UGC 01626.The follow-up this event has been initiated a few days after explosion covers period about 175 days.The early-phase light curve shows rise followed by steep decay all bands shares properties very similar to that seen case SN 1993J, with possible detection adiabatic cooling phase.Modelling quasi-bolometric suggests progenitor had an extended (∼ 1 ×...
We present spectroscopic and photometric observations of the Type IIP supernova, SN 2020jfo, in ultraviolet optical wavelengths. 2020jfo occurred spiral galaxy M61 (NGC 4303), with eight observed supernovae past 100 years. exhibited a short plateau lasting < 65 d, achieved maximum brightness V-band $M_V$ = -17.4 $\pm$ 0.4 mag at about 8.0 0.5 d since explosion. From bolometric light curve, we have estimated mass $^{56}$Ni synthesised explosion to be 0.033 0.006 $M_\odot$. The spectral...
ABSTRACT We present photometric, spectroscopic, and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 d after explosion. The peak absolute V-band magnitude SN is −15.5 mag, which fainter than that normal SNe. spectral evolution resembles other sub-luminous SNe: optical spectra show narrow P-Cygni profiles, indicating a low expansion velocity. estimate progenitor mass be about 12 $\rm {\rm M}_{\odot}$ nebular spectrum 56Ni 0.02 bolometric...
Abstract We present the long-term photometric and spectroscopic analysis of a transitioning SN IIn/Ibn from −10.8 d to 150.7 post V-band maximum. 2021foa shows prominent He i lines comparable in strength Hα line around peak, placing between IIn Ibn populations. The spectral comparison that it resembles population at pre-maximum, becomes intermediate SNe post-maximum matches with 1996al. evolution precursor −50 light curve shoulder 17d. peak luminosity color are consistent most our sample....
Sustainability is maintained by regular practices, but many factors may directly or indirectly affect sustainability in the construction industry. This paper introduces an enhancement manageability to improve that can actualize some imperative with help of ANN framework approach. The primary approach this discover present variables influence supportability development considers qualitative meta-analysis for collecting all information and contents. major problems sub-problems are identified...
In this work we have evaluated the dielectric properties of Poly Vinylidene fluoride (PVDF) thin films thickness (≈20 μm) as a function temperature from 40–70° C and frequency varying 500 Hz to 100 kHz respectively for Al‐Al Cu‐Cu electrode configuration. The constant values increases with increase in temperature. A broad peak is found at around (70±5)° C. maximum value losses were attributed phase transition polymer. variation loss tangent suggest net effect some internal field within...
Main belt asteroid (300163) 2006 VW139 (later designated P/2006 VW139) was discovered to exhibit comet-like activity by the Pan-STARRS1 survey telescope using automated point-spread-function analyses performed PS1's Moving Object Processing System. Deep follow-up observations show both a short (\sim 10") antisolar dust tail and longer 60") trail aligned with object's orbit plane, similar morphology observed for another main-belt comet, P/2010 R2 (La Sagra), other well-established comets,...
Photometric and spectral evolution of the Type Ic supernova SN 2007ru until around 210 days after maximum are presented. The spectra show broad features due to very high expansion velocity, normally seen in hypernovae. photospheric velocity is higher than other normal supernovae (SNe Ic). It lower 1998bw at ∼8 explosion, but comparable later epochs. light curve (LC) indicates a fast rise time 8 ± 3 B-band postmaximum decline more rapid broad-line SNe Ic. With an absolute V magnitude −19.06,...
We present optical spectroscopic and photometric observations of supernova (SN) 2008D, associated with the luminous X-ray transient 080109, at >300 days after explosion (nebular phases). also give flux measurements emission lines from H ii region site SN, estimates local metallicity. The brightness SN nebular phases is consistent prediction models an ejected 56Ni mass 0.07 M☉, which explains light curve early phases. [O i] line in spectrum shows a double-peaked profile while [Ca ii] does...
{Abridged} Rapid variations in optical flux are seen many quasars and all blazars. The amount of variability different classes Active Galactic Nuclei has been studied extensively but questions remain unanswered. We present the results a long-term programme to investigate intra-night (INOV) powerful flat spectrum radio core-dominated (CDQs), with focus on probing relationship INOV degree polarization. observed sample 16 bright CDQs showing strong broad emission lines consisting both high low...