Rahul Gupta

Rahul Gupta
Aryabhatta Research Institute of Observational Sciences | ARIES · Department of Astronomy and Astrophysics

Master of Science

About

48
Publications
2,549
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161
Citations
Introduction
I am Rahul Gupta, currently working as SRF at the Department of Astronomy, Aryabhatta Research Institute of Observational Sciences, India. My research work is mainly focused on time-domain astronomy (towards Gamma-ray bursts (GRBs) and their afterglows, Supernovae (SNe), and other transients) based on data from across the electromagnetic band. Presently, I am interested in prompt emission (Gamma and X-rays) spectro-polarimetric studies of GRBs using AstroSat CZTI observations.
Additional affiliations
August 2020 - May 2021
Aryabhatta Research Institute of Observational Sciences
Position
  • Senior Researcher
Description
  • I am currently working as SRF under BRICS grant.
Education
July 2015 - June 2017

Publications

Publications (48)
Article
Full-text available
We present the results of a detailed investigation of the prompt and afterglow emission in the High Energy Stereoscopic System (H.E.S.S.)-detected GRB 190829A. Swift and Fermi observations of the prompt phase of this gamma-ray burst (GRB) reveal two isolated subbursts or episodes, separated by a quiescent phase. The energetic and the spectral prope...
Preprint
Full-text available
We present and perform a detailed analysis of multi-wavelength observations of \thisgrb, an optical bright GRB with an observed reverse shock (RS) signature. Observations of this GRB were acquired with the BOOTES-4 robotic telescope, the \fermi, and the \swift missions. Time-resolved spectroscopy of the prompt emission shows that changes to the pea...
Article
Full-text available
Optical follow-up observations of optical afterglows of gamma-ray bursts are crucial to probe the geometry of outflows, emission mechanisms, energetics, and burst environments. We performed the follow-up observations of GRB 210205A and ZTF21aaeyldq (AT2021any) using the 3.6m Devasthal Optical Telescope (DOT) around one day after the burst to deeper...
Article
Full-text available
Multi-pulsed GRB 190530A, detected by the GBM and LAT onboard Fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric analysis of the prompt emission observed using AstroSat and Fermi to provide insight into the prompt emission radiation mechanisms. The time-integrated spectrum shows con...
Preprint
Full-text available
Cadmium Zinc Telluride Imager (CZTI) aboard AstroSat has been regularly detecting Gamma-Ray Bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI to attempt spectro-polarimetric studies of GRBs. Here, we present the first catalog of GRB polarization measurements made by CZTI durin...
Article
We present late-time optical follow-up observations of GRB 171010A/SN 2017htp (z = 0.33) and low-luminosity GRB 171205A/SN 2017iuk (z = 0.037) acquired using the 4K×4K CCD Imager mounted at the 3.6 m Devasthal Optical Telescope (3.6 m DOT) along with the prompt emission data analysis of these two interesting bursts. The prompt characteristics (othe...
Preprint
Full-text available
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (>2 s) duration are produced by the core-collapse of massive stars, those of short (< 2 s) duration by the merger of two neutron stars (NSs). A third class of events with hybrid high-energy properties was identified, but never concl...
Article
Full-text available
The Cadmium Zinc Telluride Imager (CZTI) on board AstroSat has been regularly detecting gamma-ray bursts (GRBs) since its launch in 2015. Its sensitivity to polarization measurements at energies above 100 keV allows CZTI to attempt spectropolarimetric studies of GRBs. Here, we present the first catalog of GRB polarization measurements made by CZTI...
Article
In this work, photometric and spectroscopic analyses of a very low-luminosity Type IIb supernova (SN) 2016iyc have been performed. SN 2016iyc lies near the faint end among the distribution of similar supernovae (SNe). Given lower ejecta mass (Mej) and low nickel mass (MNi) from the literature, combined with SN 2016iyc lying near the faint end, one-...
Preprint
Full-text available
In this work, photometric and spectroscopic analyses of a very low-luminosity Type IIb supernova (SN) 2016iyc have been performed. SN 2016iyc lies near the faint end among the distribution of similar supernovae (SNe). Given lower ejecta mass ($M_{\rm ej}$) and low nickel mass ($M_{\rm Ni}$) from the literature, combined with SN 2016iyc lying near t...
Poster
Full-text available
The emission processes responsible for the prompt emission of gamma-ray bursts (GRBs) are still an open question. Besides temporal and spectral properties, hard X-ray/ gamma-ray polarization measurement is thought to be a powerful tool for probing the radiation mechanisms of GRBs since the emission mechanisms invoked to explain prompt emission are...
Preprint
Full-text available
We present a detailed analysis of short GRB 201221D lying at redshift $z= 1.045$. We analyse the high-energy data of the burst and compare it with the sample of short gamma-ray bursts (SGRBs). The prompt emission characteristics are typical of those seen in the case of other SGRBs except for the peak energy ($E_{\rm p}$), which lies at the softer e...
Preprint
Full-text available
We present late-time optical follow-up observations of GRB 171010A/SN 2017htp ($z$ = 0.33) and low-luminosity GRB 171205A/SN 2017iuk ($z$ = 0.037) acquired using the 4K$\times$4K CCD Imager mounted at the 3.6m Devasthal Optical Telescope (3.6m DOT) along with the prompt emission data analysis of these two interesting bursts. The prompt characterist...
Article
Full-text available
In this work, we study the synthetic explosions of a massive star. We take a 100 \(M_{\odot }\) zero-age main-sequence (ZAMS) star and evolve it until the onset of core-collapse using MESA. Then, the resulting star model is exploded using the publicly available stellar explosion code, STELLA. The outputs of STELLA calculations provide the bolometri...
Preprint
Full-text available
In this work, we study the synthetic explosions of a massive star. We take a 100 M$_{\odot}$ zero--age main--sequence (ZAMS) star and evolve it until the onset of core-collapse using {\tt MESA}. Then, the resulting star model is exploded using the publicly available stellar explosion code, {\tt STELLA}. The outputs of {\tt STELLA} calculations prov...
Preprint
Full-text available
In this work, we employ two publicly available analysis tools to study four hydrogen(H)--stripped core--collapse supernovae (CCSNe) namely, SN 2009jf, iPTF13bvn, SN 2015ap, and SN 2016bau. We use the Modular Open-Source Fitter for Transients ({\tt MOSFiT}) to model the multi band light curves. {\tt MOSFiT} analyses show ejecta masses (log M$_{ej}$)...
Preprint
Full-text available
In this article, we present multi-band photometric observations and analysis of the host galaxies for a sample of five interesting gamma-ray bursts (GRBs) observed using the 3.6m Devasthal Optical Telescope (DOT) and the back-end instruments. The host galaxy observations of GRBs provide unique opportunities to estimate the stellar mass, ages, star-...
Preprint
Full-text available
We report detailed prompt emission observations and analysis of the very bright and long GRB 210619B, detected by the Atmosphere-Space Interactions Monitor (ASIM) installed on the International Space Station ({\it ISS}) and the Gamma-ray Burst Monitor (GBM) on-board the Fermi mission. Our main goal is to understand the radiation mechanisms and jet...
Preprint
Full-text available
We present results from extensive broadband follow-up of GRB 210204A over the period of thirty days. We detect optical flares in the afterglow at 7.6 x 10^5 s and 1.1 x 10^6 s after the burst: the most delayed flaring ever detected in a GRB afterglow. At the source redshift of 0.876, the rest-frame delay is 5.8 x 10^5 s (6.71 d). We investigate pos...
Poster
Full-text available
We present the poster titled 'Probing into emission mechanisms of \thisgrb using time-resolved spectra and polarization studies: Synchrotron Origin? In this work, we have explored different aspects of the prompt emission and afterglow of multi-pulsed GRB 190530A (the sixth most fluent GBM burst detected so far) detected by the GBM and LAT and compa...
Preprint
Full-text available
Gamma-ray bursts are traditionally classified as short and long bursts based on their T90 value (the time interval during which an instrument observes 5% to 95% of gamma-ray/hard X-ray fluence). However, T90 is dependent on the detector sensitivity and the energy range in which the instrument operates. As a result, different instruments provide dif...
Preprint
Full-text available
Multi-pulsed GRB 190530A, detected by the GBM and LAT onboard \fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric analysis of the prompt emission observed using \AstroSat and \fermi to provide insight into the prompt emission radiation mechanisms. The time-integrated spectrum shows...
Preprint
Full-text available
Optical follow-up observations of optical afterglows of gamma-ray bursts are crucial to probe the geometry of outflows, emission mechanisms, energetics, and burst environments. We performed the follow-up observations of GRB 210205A and ZTF21aaeyldq (AT2021any) using the 3.6m Devasthal Optical Telescope (DOT) around one day after the burst to deeper...
Poster
Full-text available
H-deficient superluminous supernovae (SLSNe I) are nearly 2-3 magnitudes brighter than the classical core-collapse SNe (CCSNe), radiating total energy of the order of 10 51 erg and exhibiting characteristic W-shaped O II features towards blue in the near-peak spectra (Quimby et al. 2011, Natur, 474, 487, Nicholl 2021, A&G, 62, 5.34). SLSNe I appear...
Article
Full-text available
Giant flares (GFs) are unusual bursts from soft gamma-ray repeaters (SGRs) that release an enormous amount of energy in a fraction of a second. The afterglow emission of these SGR-GFs or GF candidates is a highly beneficial means of discerning their composition, relativistic speed, and emission mechanisms. GRB 200415A is a recent GF candidate obser...
Article
Full-text available
Newly installed 3.6m DOT at Nainital (Uttarakhand) is a novel facility for the time domain astronomy. Because of the longitudinal advantage of India, it could be used to study new transients reported by a global network of robotic telescopes. Observations with the 4K × 4K CCD Imager at the axial port of the 3.6m DOT will be very helpful in the near...
Article
Full-text available
We explore the study of energetic transients including core-collapse supernovae using various publicly available analysis tools like MESA & SNEC, MOSFiT and SNCOSMO. We used MESA to evolve a star having zero age main sequence mass (Mzams) of 24 M⊙ until the onset of core-collapse. Then we exploded this model using openly available explosion codes,...
Preprint
Full-text available
Optical, near-infrared (NIR) photometric and spectroscopic studies along with the optical imaging polarimetric results for SN 2012au to constrain the nature of the progenitor and other properties are presented in this paper. Well-calibrated multi-band optical photometric data (from -0.2 to +413 d since B-band maximum) was used to compute the bolome...
Article
Full-text available
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN 2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, syn...
Poster
Full-text available
Superluminous supernovae (SLSNe) are a new class of SNe (2–3 magnitudes brighter than classical SNe) that were recognized about a decade ago (Quimby et al. 2011). SLSNe comprising ∼0.01 per cent of normal core-collapse SNe (CCSNe), and nearly 150 objects have been spectroscopically confirmed so far. Like classical CCSNe, SLSNe are spectroscopically...
Article
Full-text available
We present and perform a detailed analysis of multi-wavelength observations of \thisgrb, an optical bright GRB with an observed reverse shock (RS) signature. Observations of this GRB were acquired with the BOOTES-4 robotic telescope, the \fermi, and the \swift missions. Time-resolved spectroscopy of the prompt emission shows that changes to the pea...
Article
Full-text available
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN~2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, syn...
Preprint
Full-text available
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN~2016bau are discussed. Photometric properties of the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, syn...
Article
Full-text available
We present radio and optical afterglow observations of the TeV-bright long gamma-ray burst 190114C at a redshift of z = 0.425, which was detected by the Major Atmospheric Gamma Imaging Cherenkov telescope. Our observations with Atacama Large Millimeter/submillitmeter Array, Australia Telescope Compact Array, and upgraded Giant Metre-wave Radio Tele...
Article
Full-text available
We investigate the observational properties of a hydrogen-deficient superluminous supernova (SLSN) SN 2020ank (at z = 0.2485), with the help of early phase observations carried out between –21 and +52 d since g-band maximum. Photometrically, SN 2020ank is one of the brightest SLSN (Mg, peak ∼ –21.84 ± 0.10 mag), having fast pre-peak rising and post...
Conference Paper
Newly installed 3.6m DOT at Nainital (Uttarakhand) is a novel facility for the time domain astronomy. Because of India's longitudinal advantage, it could be used to study new transients reported by a global network of robotic telescopes. Observations with the 4K×4K CCD Imager at the axial port of the 3.6m DOT will be very helpful in the near future...
Preprint
Full-text available
We investigate the observational properties of a hydrogen-deficient superluminous supernova (SLSN) SN 2020ank (at z = 0.2485), with the help of early phase observations carried out between $-$21 and +52 d since $g$-band maximum. Photometrically, SN 2020ank is one of the brightest SLSN ($M_{g,peak}$ $\sim$ $-$21.84 $\pm$ 0.10 mag), having fast pre-p...
Article
Full-text available
Aims. Gamma-ray burst (GRB) 190829A ( z = 0.0785) was detected by Fermi and Swift and also at very high energy (VHE) by the High-Energy Stereoscopic System (H.E.S.S.) telescopes. The prompt emission displayed two emission episodes separated by a quiescent gap of ∼40 s. We present the 10.4 m Gran Telescopio Canarias (GTC) observations of the aftergl...
Preprint
Full-text available
Aims. GRB 190829A (z = 0.0785), detected by Fermi and Swift with two emission episodes separated by a quiescent gap of ~40 s, was also observed by the H.E.S.S. telescopes at Very-High Energy (VHE). We present the 10.4m GTC observations of the afterglow of GRB 190829A and underlying supernova and compare it against a similar GRB 180728A and discuss...
Conference Paper
Full-text available
TeV emissions from γ-ray bursts are very important to study their origin and the radiation mechanisms in detail. Recent observations of TeV photons in some of the GRBs are challenging to be explained by the traditional Synchrotron radiation mechanism. In this work, we present the results of a detailed investigation of the prompt and afterglow emiss...
Preprint
Full-text available
Giant flares (GFs) are unusual bursts from soft gamma-ray repeaters (SGRs) that release an enormous amount of energy in a fraction of a second. The afterglow emission of these SGR-GFs or GF candidates is a highly beneficial means of discerning their composition, relativistic speed, and emission mechanisms. GRB 200415A is a recent GF candidate obser...
Preprint
Full-text available
We present the results of a detailed investigation of the prompt and afterglow emission in the HESS detected GRB 190829A. Swift and Fermi observations of the prompt phase of this GRB reveal two isolated sub-bursts or episodes, separated by a quiescent phase. The energetic and the spectral properties of the first episode are in stark contrast to the...
Article
This paper presents data and analysis of SN 2010kd, a low-redshift (z = 0.101) H-deficient superluminous supernova (SLSN), based on ultraviolet/optical photometry and optical spectroscopy spanning between -28 and +194 days relative to B-band maximum light. The B-band light-curve comparison of SN 2010kd with a subset of well-studied SLSNe I at compa...
Preprint
Full-text available
This paper presents data and analysis of SN 2010kd, a low-redshift ($z = 0.101$) H-deficient superluminous supernova (SLSN), based on ultraviolet/optical photometry and optical spectroscopy spanning between $-$28 and +194 days relative to $\mathit{B}$ band maximum light. The $\mathit{B}$ band light curve comparison of SN 2010kd with a subset of wel...
Article
Full-text available
We investigate the prompt emission and the afterglow properties of short-duration gamma-ray burst (sGRB) 130603B and another eight sGRB events during 2012-2015, observed by several multi-wavelength facilities including the GTC 10.4 m telescope. Prompt emission high energy data of the events were obtained by INT EGRAL-SPI-ACS, S wi f t-BAT and Fermi...
Preprint
Full-text available
We investigate the prompt emission and the afterglow properties of short duration gamma-ray burst (sGRB) 130603B and another eight sGRB events during 2012-2015, observed by several multi-wavelength facilities including the GTC 10.4m telescope. Prompt emission high energy data of the events were obtained by INTEGRAL/SPI/ACS, Swift/BAT and Fermi/GBM...
Conference Paper
Full-text available
We demonstrate the study of energetic transients including core-collapse supernovae using various publicly available analysis tools like MESA & SNEC, MOSFiT and SNCOSMO. We used MESA to evolve a star having zero age main sequence mass (M zams) of 24 M until the onset of core-collapse. Then we exploded this model using openly available explosion cod...

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Projects

Projects (6)
Project
We propose to make a detailed investigation of the spectral, temporal, and polarimetric characteristics of eleven bright gamma-ray bursts (GRBs) using archival data from the CZTI instrument of AstroSat. These GRBs are detected by CZTI during its first year of operation and the average polarisation characteristics of these GRBs are already published. In the present proposal, we plan to make an improved polarimetric study of these GRBs by doing a systematic and uniform analysis incorporating several new features developed by the CZTI team like increasing the effective area and bandwidth (by using data from low-gain pixels), using an improved event selection logic to reduce noise in the double events, and extend the spectral bandwidth. By these improved analysis methods, we propose to make a detailed energy-resolved and time-resolved spectro-polarimetric study of these GRBs to pin down the elusive prompt emission mechanism.
Project
Optical follow-up observations of optical afterglows of gamma-ray bursts are crucial to probe the geometry of outflows, emission mechanisms, energetics, and burst environments. Under this project, we plan to perform early to late-time optical follow-up observations of the optical afterglow of interesting GRBs.