Publications (94)
The luminous Type IIN supernova SN 2017hcc: Infrared bright, X-ray and radio faint
Poonam Chandra, Roger A. Chevalier, Nicholas J. H. James +1
We present multiwavelength observations of supernova (SN) 2017hcc with the Chandra X-ray telescope and the X-ray telescope onboard Swift (Swift-XRT) in X-ray bands, with the Spitze…
Circumstellar interaction in supernovae in dense environments - an observational perspective
Poonam Chandra
In a supernova explosion, the ejecta interacting with the surrounding circumstellar medium (CSM) give rise to variety of radiation. Since CSM is created from the mass lost from the…
Pre-existing dwarfs, tidal knots and a tidal dwarf galaxy: an unbiased HI study of the gas-rich interacting galaxy group NGC 3166/9
Karen Lee-Waddell, Kristine Spekkens, Martha P. Haynes +4
We present Arecibo Legacy Fast ALFA (ALFALFA) and follow-up Giant Metrewave Radio Telescope (GMRT) HI observations of the gas-rich interacting group NGC 3166/9. The sensitive ALFAL…
The X-ray and Radio Loud Fast Blue Optical Transient AT2020mrf: Implications for an Emerging Class of Engine-Driven Massive Star Explosions
Yuhan Yao, Anna Y. Q. Ho, Pavel Medvedev +9
We present AT2020mrf (SRGe J154754.2443907), an extra-galactic () fast blue optical transient (FBOT) with a rise time of days and a peak luminosit…
Coherent radio emission from 'Main-sequence Radio Pulse emitters': a new stellar diagnostic to probe 3D magnetospheric structures
Barnali Das, Poonam Chandra, Veronique Petit
Main-sequence Radio Pulse emitters (MRPs) are magnetic early-type stars that produce coherent radio emission observed in the form of periodic radio pulses. The emission mechanism b…
Electron Cooling in a Young Radio Supernova: SN 2012aw
Naveen Yadav, Alak Ray, Sayan Chakraborti +8
We present the radio observations and modeling of an optically bright Type II-P supernova (SN), SN 2012aw which exploded in the nearby galaxy Messier 95 (M95) at a distance of $10\…
Probing Final Stages of Stellar Evolution with X-Ray Observations of SN 2013ej
Sayan Chakraborti, Alak Ray, Randall Smith +8
Massive stars shape their surroundings with mass loss from winds during their lifetimes. Fast ejecta from supernovae, from these massive stars, shocks this circumstellar medium. Em…
A Multi-Wavelength View on the Rapidly-Evolving Supernova 2018ivc: An Analog of SN IIb 1993J but Powered Primarily by Circumstellar Interaction
Keiichi Maeda, Poonam Chandra, Takashi J. Moriya +15
SN 2018ivc is an unusual type II supernova (SN II). It is a variant of SNe IIL, which might represent a transitional case between SNe IIP with a massive H-rich envelope, and IIb wi…
Strong Evolution of X-Ray Absorption in the Type IIn Supernova SN 2010jl
Poonam Chandra, Roger A. Chevalier, Christopher M. Irwin +3
We report two epochs of Chandra-ACIS X-ray imaging spectroscopy of the nearby bright Type IIn supernova SN 2010jl, taken around 2 months and then a year after the explosion. The ma…
Discoveries of fine structures and secondary pulses in coherent radio emission from a magnetic massive star
Barnali Das, Poonam Chandra, William Cotton +1
In this paper, we report auroral radio emission from a magnetic B star HD 142990 using the MeerKAT radio telescope at MHz. The star is known to produce such emission (ob…
Discovery of Radio Afterglow from the Most Distant Cosmic Explosion
Poonam Chandra, Dale A. Frail, Derek Fox +6
We report the discovery of radio afterglow emission from the gamma-ray burst GRB 090423, which exploded at a redshift of 8.3, making it the object with the highest known redshift i…
Chandra's tryst with SN 1995N
Poonam Chandra, Alak Ray, Eric M. Schlegel +2
We present the spectroscopic and imaging analysis of a type IIn supernova SN 1995N observed with the Chandra X-ray observatory on 2004 March 27. We compare the spectrum obtained fr…
Giant Metrewave Radio Telescope monitoring of the black hole X-ray binary, V404 Cygni, during its June 2015 outburst
Poonam Chandra, Nissim Kanekar
We report results from a Giant Metrewave Radio Telescope (GMRT) monitoring campaign on the black hole X-ray binary V404 Cygni during its 2015 June outburst. The GMRT observations w…
Resurrection of type IIL supernova 2018ivc: Implications for a binary evolution sequence connecting hydrogen-rich and -poor progenitors
Keiichi Maeda, Tomonari Michiyama, Poonam Chandra +4
Long-term observations of synchrotron emission from supernovae (SNe), covering more than a year after the explosion, provide a unique opportunity to study the poorly-understood evo…
Accounting for Selection Bias and Redshift Evolution in GRB Radio Afterglow Data
Maria Dainotti, Delina Levine, Nissim Fraija +1
Gamma-ray Bursts (GRBs) are highly energetic events that can be observed at extremely high redshift. However, inherent bias in GRB data due to selection effects and redshift evolut…
The Nature of Optical Afterglows Without Gamma-ray Bursts: Identification of AT2023lcr and Multiwavelength Modeling
Maggie L. Li, Anna Y. Q. Ho, Geoffrey Ryan +29
In the past few years, the improved sensitivity and cadence of wide-field optical surveys have enabled the discovery of several afterglows without associated detected gamma-ray bur…
A candidate relativistic tidal disruption event at 340 Mpc
Jean J. Somalwar, Vikram Ravi, Dillon Z. Dong +13
We present observations of an extreme radio flare, VT J024345.70-284040.08, hereafter VT J0243, from the nucleus of a galaxy with evidence for historic Seyfert activity at redshift…
Gamma Ray Bursts -- A radio perspective
Poonam Chandra
Gamma-ray bursts (GRBs) are extremely energetic events at cosmological distances. They provide unique laboratory to investigate fundamental physical processes under extreme conditi…
Modeling the X-ray emission of SN 1993J
Tanja K. Nymark, Poonam Chandra, Claes Fransson
We investigate the effects of radiative shocks on the observed X-ray emission from the Type II supernova SN 1993J. To this end, the X-ray emission is modeled as a result of the int…
The fifth main sequence magnetic B-type star showing coherent radio emission: is this really a rare phenomenon?
Barnali Das, Poonam Chandra, Matt. E. Shultz +1
We report the discovery of intense, highly directional radio emission from the Bp star HD 35298, which we interpret as the consequence of Electron Cyclotron Maser Emission (ECME).…
Discovery of eight 'Main-sequence Radio Pulse emitters' using the GMRT: clues to the onset of coherent radio emission in hot magnetic stars
Barnali Das, Poonam Chandra, Matt E. Shultz +6
'Main-sequence radio pulse-emitters' (MRPs) are magnetic early-type stars from which periodic radio pulses, produced via electron cyclotron maser emission (ECME), are observed. Des…
Detection of coherent emission from the Bp star HD 142990 at uGMRT frequencies
Barnali Das, Poonam Chandra, M. E. Shultz +1
HD 142990 is a Bp-type star with a nearly dipolar surface magnetic field of kG strength. Recently Lenc et al. (2018) reported the tentative discovery of Electron Cyclotron Maser Em…
Testing a scaling relation between coherent radio emission and physical parameters of hot magnetic stars
Barnali Das, Poonam Chandra, Matt E. Shultz +4
Coherent radio emission via electron cyclotron maser emission (ECME) from hot magnetic stars was discovered more than two decades ago, but the physical conditions that make the gen…
Explosive and radio-selected Transients: Transient Astronomy with SKA and its Precursors
Poonam Chandra, G. C. Anupama, K. G. Arun +7
With the high sensitivity and wide-field coverage of the Square Kilometre Array (SKA), large samples of explosive transients are expected to be discovered. Radio wavelengths, espec…
The progenitor of SN 2011ja: Clues from circumstellar interaction
Sayan Chakraborti, Alak Ray, Randall Smith +7
Massive stars, possibly red supergiants, which retain extended hydrogen envelopes until core collapse, produce Type II Plateau (IIP) supernovae. The ejecta from these explosions sh…
The Panchromatic Afterglow of GW170817: The full uniform dataset, modeling, comparison with previous results and implications
Sphesihle Makhathini, Kunal P. Mooley, Murray Brightman +35
We present the full panchromatic afterglow light curve data of GW170817, including new radio data as well as archival optical and X-ray data, between 0.5 and 940 days post-merger.…
Radio evolution of a Type IIb supernova SN 2016gkg
A. J. Nayana, Poonam Chandra, Anoop Krishna +1
We present extensive radio monitoring of a type IIb supernova (SN IIb), SN 2016gkg during 81429 days post explosion at frequencies 0.3325 GHz. The detailed…
Discovery and confirmation of the shortest gamma ray burst from a collapsar
Tomas Ahumada, Leo P. Singer, Shreya Anand +54
Gamma-ray bursts (GRBs) are among the brightest and most energetic events in the universe. The duration and hardness distribution of GRBs has two clusters, now understood to reflec…
Low-frequency GMRT observations of ultra-cool dwarfs
Andrew Zic, Christene Lynch, Tara Murphy +2
Observations of radio emission in about 10 per cent of ultra-cool dwarfs (UCDs) indicate the presence of strong, persistent magnetic fields in these stars. These results are in con…
Discovery of electron cyclotron MASER emission from the magnetic Bp star HD 133880 with the Giant Metrewave Radio Telescope
Barnali Das, Poonam Chandra, Gregg A. Wade
We report the discovery of coherent radio emission from the young, rapidly-rotating magnetic Bp star HD 133880 at a frequency of 610 MHz with the Giant Metrewave Radio Telescope (G…
X-rays from the explosion site: Fifteen years of light curves of SN 1993J
Poonam Chandra, Vikram V. Dwarkadas, Alak Ray +2
We present a comprehensive analysis of the X-ray light curves of SN 1993J in a nearby galaxy M81. This is the only supernova other than SN 1987A, which is so extensively followed i…
Star-Planet Interaction at radio wavelengths in YZ Ceti: Inferring planetary magnetic field
Corrado Trigilio, Ayan Biswas, Paolo Leto +13
In exoplanetary systems, the interaction between the central star and the planet can trigger Auroral Radio Emission (ARE), due to the Electron Cyclotron Maser mechanism. The high b…
Supernova Interaction with a Dense Detached Shell in SN 2001em
Poonam Chandra, Roger A. Chevalier, Nikolai Chugai +2
We carry out a comprehensive analysis of supernova \snem\ covering a period of 19 years since discovery. SN 2001em is the oldest supernova known to have undergone a metamorphosis f…
Unraveling the complex magnetosphere of the B star HD 133880 via wideband observation of coherent radio emission
Barnali Das, Poonam Chandra, Gregg A. Wade
HD 133880 is one of the six hot magnetic stars known to produce coherent pulsed radio emission by the process of electron cyclotron maser emission (ECME). In this paper, we present…
Chandra's insights into SN 2023ixf
Poonam Chandra, Roger A. Chevalier, Keiichi Maeda +2
We report Chandra-ACIS observations of SN 2023ixf in M101 on day 13 and 86 since the explosion. The X-rays in both epochs are characterized by high temperature plasma from the forw…
A Radio-Selected Sample of Gamma Ray Burst Afterglows
Poonam Chandra, Dale A. Frail
We present a catalog of radio afterglow observations of gamma-ray bursts (GRBs) over a 14 year period from 1997 to 2011. Our sample of 304 afterglows consists of 2995 flux density…
SN 2021foa: the bridge between SN IIn and Ibn
Anjasha Gangopadhyay, Naveen Dukiya, Takashi J Moriya +26
We present the long-term photometric and spectroscopic analysis of a transitioning SN~IIn/Ibn from 10.8 d to 150.7 d post -band maximum. SN~2021foa shows prominent He {\sc i}…
Probing the magnetospheres of hot magnetic stars using ECME
Barnali Das, Poonam Chandra, Gregg A. Wade +2
We discuss Electron Cyclotron Maser Emission (ECME), observed in the form of highly circularly polarized pulses, from a few hot magnetic stars. This emission is one of the manifest…
Supernovae with the Square Kilometre Array
Poonam Chandra, Yuhei Iwata, A. J. Nayana +2
This chapter presents the science potential of the Square Kilometre Array (SKA) for studying all classes of supernovae and their environments. It substantially updates and extends…
Baby supernovae through the looking glass at long wavelengths
Poonam Chandra, Alak Ray
We emphasize the importance of observations of young supernovae in wide radio band. We argue on the basis of observational results that only high or only low frequency data is not…
Multi-Wavelength Analysis of AT 2023sva: a Luminous Orphan Afterglow With Evidence for a Structured Jet
Gokul P. Srinivasaragavan, Daniel A. Perley, Anna Y. Q. Ho +50
We present multi-wavelength analysis of ZTF23abelseb (AT 2023sva), an optically discovered fast-fading ( mag in days), luminous ( mag) an…
Discovery of Magnetospheric Interactions in the Doubly-Magnetic Hot Binary Lupi
Ayan Biswas, Barnali Das, Poonam Chandra +6
Magnetic fields are extremely rare in close, hot binaries, with only 1.5\% of such systems known to contain a magnetic star. The eccentric Lupi system stands out in this popul…
A detailed study of the polarisation convention of the Giant Metrewave Radio Telescope
Poonam Chandra, S. Suresh Kumar, Sanjay Kudale +5
Our work aims to investigate the polarisation convention of the Giant Metrewave Radio Telescope (GMRT) radio telescope and understand whether the telescope follows the standard IAU…
Rubin ToO 2024: Envisioning the Vera C. Rubin Observatory LSST Target of Opportunity program
Igor Andreoni, Raffaella Margutti, John Banovetz +86
The Legacy Survey of Space and Time (LSST) at Vera C. Rubin Observatory is planned to begin in the Fall of 2025. The LSST survey cadence has been designed via a community-driven pr…
Next Generation Observatories -- Report from the Dawn VI Workshop; October 5-7 2021
D. H. Shoemaker, Stefan Ballmer, Matteo Barsuglia +33
The workshop Dawn VI: Next Generation Observatories took place online over three days, 5-7 October, 2021. More than 200 physicists and astronomers attended to contribute to, and le…
GRB 230204B: GIT Discovery of a Fast Fading Afterglow Associated with an Energetic GRB from a Massive-Star Progenitor
Vishwajeet Swain, Varun Bhalerao, Harsh Kumar +19
We present a comprehensive multi-wavelength study of a bright gamma-ray burst GRB 230204B, analyzing both prompt and afterglow emissions. This GRB is highly energetic, with an isot…
The final months of massive star evolution from the circumstellar environment around SN Ic 2020oi
Keiichi Maeda, Poonam Chandra, Tomoki Matsuoka +8
We present the results of ALMA band 3 observations of a nearby type Ic supernova (SN) 2020oi. Under the standard assumptions on the SN-circumstellar medium (CSM) interaction and th…
Evolution of the progenitors of SNe 1993J and 2011dh revealed through late time radio and X-ray studies
Esha Kundu, Peter Lundqvist, Elena Sorokina +6
We perform hydrodynamical simulations of the interaction between supernova (SN) ejecta and circumstellar medium (CSM) for SN 1993J and SN 2011dh, and calculate the radio and X-ray…
Bridging between type IIb and Ib supernovae: SN IIb 2022crv with a very thin Hydrogen envelope
Anjasha Gangopadhyay, Keiichi Maeda, Avinash Singh +26
We present optical, near-infrared, and radio observations of supernova (SN) SN~IIb 2022crv. We show that it retained a very thin H envelope and transitioned from a SN~IIb to a SN~I…
X-ray and radio emission from Type IIn supernova SN 2010jl
Poonam Chandra, Roger A. Chevalier, Nikolai Chugai +2
We present all X-ray and radio observations of the Type IIn supernova SN 2010jl. The X-ray observations cover a period up to day 1500 with Chandra, XMM-Newton, NuSTAR and Swift-XRT…
Multiwavelength Analysis of Six Luminous Fast Blue Optical Transients
Cassie Sevilla, Anna Y. Q. Ho, Nayana A. J. +43
We present multiwavelength observations and analysis of six luminous fast blue optical transients (LFBOTs) discovered in Zwicky Transient Facility (ZTF) survey data. We identified…
Eleven years of radio monitoring of the Type IIn supernova SN 1995N
Poonam Chandra, Christopher J. Stockdale, Roger A. Chevalier +6
We present radio observations of the optically bright Type IIn supernova SN 1995N. We observed the SN at radio wavelengths with the Very Large Array (VLA) for 11 years. We also obs…
Uncovering the Putative B-Star Binary Companion of the SN 1993J Progenitor
Ori D. Fox, K. Azalee Bostroem, Schuyler D. Van Dyk +9
The Type IIb supernova (SN) 1993J is one of only a few stripped-envelope supernovae with a progenitor star identified in pre-explosion images. SN IIb models typically invoke H enve…
XMM-Newton Perspective of the Unique Magnetic Binary- Lupi
Ayan Biswas, Gregg A. Wade, Poonam Chandra +3
The Lupi A (HD 136504) system stands out among magnetic massive binaries as the only short-period binary system in which both components have detectable magnetic fields. The p…
Identification of a Radio Counterpart to SN 2025ulz in the S250818k Localization Area
Tanner O'Dwyer, Alessandra Corsi, Deepika Yadav +12
On 2025 August 18, the LIGO-Virgo-KAGRA collaboration reported S250818k, a sub-threshold gravitational-wave (GW) candidate consistent with a binary neutron star (NS) merger potenti…
325 and 610 MHz Radio Counterparts of SNR G353.60.7 a.k.a. HESS J1731347
A. J. Nayana, Poonam Chandra, Subhashis Roy +6
HESS J1731347 a.k.a. SNR G353.60.7 is one of the five known shell-type supernova remnants (SNRs) emitting in the very high energy (VHE, Energy 0.1 TeV) -ray domain. W…
Radio Studies of Young Core Collapse Supernovae
Poonam Chandra, Alak Ray, Sanjay Bhatnagar
Multi-frequency observations of two radio bright SNe (SN1993J, SN1979C) carried out over a year with GMRT are presented. Their radio light curves trace the evolution of the mass lo…
A multiwavelength view of the nearby Calcium-Strong Transient SN 2025coe in the X-Ray, Near-Infrared, and Radio Wavebands
Sahana Kumar, Raphael Baer-Way, Aravind P. Ravi +18
Calcium-strong transients (CaSTs) are a subclass of faint and rapidly evolving supernovae (SNe) that exhibit strong calcium features and notably weak oxygen features. The small but…
A very luminous jet from the disruption of a star by a massive black hole
Igor Andreoni, Michael W. Coughlin, Daniel A. Perley +78
Tidal disruption events (TDEs) are bursts of electromagnetic energy released when supermassive black holes (SMBHs) at the centers of galaxies violently disrupt a star that passes t…
Type Ib supernova Master OT J120451.50+265946.6: radio emitting shock with inhomogeneities crossing through a dense shell
Poonam Chandra, A. J. Nayana, Claes-Ingvar Bjornsson +4
We present radio observations of a Type Ib supernova (SN) Master OT J120451.50+265946.6. Our low frequency Giant Metrewave Radio Telescope (GMRT) data taken when the SN was in the…
Radio emission from a decade old Type I superluminous supernova, PTF10hgi: Comparison with FRB121102
Surajit Mondal, Apurba Bera, Poonam Chandra +1
We perform a comparative study between the only radio detected Type I superluminous supernova (SLSN) PTF10hgi, and the most active repeating fast radio burst FRB121102. This study…
The long-active afterglow of GRB 210204A: Detection of the most delayed flares in a Gamma-Ray Burst
Harsh Kumar, Rahul Gupta, Divita Saraogi +22
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 afte…
Radio studies of supernovae 1979C, 1986J and 2006X with LOFAR
Peter Lundqvist, Deeepika Venkattu, Miguel Pérez Torres +3
We present LOw Frequency ARray (LOFAR) studies of supernovae SN 1979C, SN 1986J, and SN 2006X, focusing on new observations from the LOFAR Two-metre Sky Survey (LoTSS) and the Inte…
Implications of aging in young supernovae
Poonam Chandra, Alak Ray
We present here the combined radio spectrum from the Giant Metrewave Radio Telescope (GMRT) and Very Large Array (VLA) of type-IIb SN 1993J (age 11 years) and a type-Ic SN 2003bg (…
Centrifugal breakout reconnection as the electron acceleration mechanism powering the radio magnetospheres of early-type stars
Stanley P Owocki, Matt E. Shultz, Asif ud-Doula +3
Magnetic B-stars often exhibit circularly polarized radio emission thought to arise from gyrosynchrotron emission by energetic electrons trapped in the circumstellar magnetosphere.…
A comprehensive study of GRB 070125, a most energetic gamma ray burst
Poonam Chandra, S. Bradley Cenko, Dale Frail +21
We present a comprehensive multiwavelength analysis of the bright, long duration gamma-ray burst GRB 070125, comprised of observations in -ray, X-ray, optical, millimeter and c…
Radio and X-ray Observations of the Transitional Supernova 2019yvr: Insights into the Progenitor Mass-Loss History
Raphael Baer-way, Poonam Chandra, Maryam Modjaz +7
The final life stages of the massive star progenitors of stripped-envelope supernovae (SESNe) are still an open question, especially when it comes to the timing and magnitude of th…
Fading Echoes of Interaction: Probing Centuries of Preexplosion Mass-Loss in Four Type IIn Supernovae
Elizabeth Hillenkamp, Raphael Baer-Way, Poonam Chandra +6
Supernovae characterized by enduring narrow optical hydrogen emission lines (SNe IIn) are believed to result primarily from the core-collapse of massive stars undergoing sustained…
Ultra-Wideband, Multi-epoch Radio Study of the First Discovered `Main sequence Radio Pulse emitter' CU Vir
Barnali Das, Poonam Chandra
Presence of large-scale surface magnetic field in early-type stars leads to several unique electromagnetic phenomena producing radiation over X-ray to radio bands. Among them, the…
A JVLA survey of the high frequency radio emission of the massive magnetic B- and O-type stars
Sushma Kurapati, Poonam Chandra, Gregg Wade +10
We conducted a survey of seven magnetic O and eleven B-type stars with masses above using the Very Large Array in the 1cm, 3cm and 13cm bands. The survey resulted in a…
X-Ray emission from SN 2004dj: A Tale of Two Shocks
Sayan Chakraborti, Naveen Yadav, Alak Ray +2
Type IIP (Plateau) Supernovae are the most commonly observed variety of core collapse events. They have been detected in a wide range of wavelengths from radio, through optical to…
Examining Two-Dimensional Luminosity-time Correlations for Gamma Ray Burst Radio Afterglows with VLA and ALMA
Delina Levine, Maria Dainotti, Kevin J. Zvonarek +4
Gamma-ray burst (GRB) afterglow emission can be observed from sub-TeV to radio wavelengths, though only 6.6\% of observed GRBs present radio afterglows. We examine GRB radio light…
Multiwavelength view of circumstellar interaction in supernovae
Poonam Chandra
The interaction of post-explosion supernova ejecta with the surrounding circumstellar medium creates emission across the electromagnetic spectrum. Since the circumstellar medium is…
Long term behaviour of a Type IIP supernova SN 2004dj in the radio bands
Nayana A J, Poonam Chandra, Alak K. Ray
We present radio observations and modelling of one of the nearest and brightest Type IIP supernova SN\,2004dj exploded in the galaxy NGC 2403 at a distance of 3.5 Mpc. Our o…
Peculiar spectral property of coherent radio emission from a hot magnetic star: the case of an extreme oblique rotator
Barnali Das, Poonam Chandra
We report ultra-wideband (0.4-4.0 GHz) observation of coherent radio emission via electron cyclotron maser emission (ECME) produced by the hot magnetic star HD 142990. With nearly…
Synchrotron aging and the radio spectrum of SN 1993J
Poonam Chandra, Alak Ray, Sanjay Bhatnagar
We combine the GMRT low frequency radio observations of SN 1993J with the VLA high frequency radio data to get a near simultaneous spectrum around day 3200 since explosion. The low…
Ultra High Energy Cosmic Ray Acceleration in Engine-driven Relativistic Supernovae
Sayan Chakraborti, Alak Ray, Alicia Soderberg +2
The origin of the highest energy cosmic rays remains an enigma. They offer a window to new physics, including tests of physical laws relevant to their propagation and interactions,…
Type IIP Supernova SN 2004et: A Multi-Wavelength Study in X-Ray, Optical and Radio
Kuntal Misra, Dave Pooley, Poonam Chandra +4
We present X-ray, broad band optical and low frequency radio observations of the bright type IIP supernova SN 2004et. The \cxo observed the supernova at three epochs, and the optic…
Same explosion, many faces: numerical modeling reveals viewing angle as a driver of diversity for core-collapse SNe in binary systems
Soham Mandal, Raphael Baer-way, Shazrene Mohamed +3
The study uses binary evolution and radiation‑hydrodynamics simulations to show that asymmetric circumstellar material produced by binary interaction creates strong viewing‑angle d…
Dinosaur in a Haystack : X-ray View of the Entrails of SN 2023ixf and the Radio Afterglow of Its Interaction with the Medium Spawned by the Progenitor Star (Paper 1)
A. J. Nayana, Raffaella Margutti, Eli Wiston +24
We present the results from our extensive hard-to-soft X-ray (NuSTAR, Swift-XRT, XMM-Newton, Chandra) and meter-to-mm wave radio (GMRT, VLA, NOEMA) monitoring campaign of the very…
A Multiwavelength Autopsy of the Interacting IIn Supernova 2020ywx: Tracing its Progenitor Mass-Loss History for 100 Years before Death
Raphael Baer-Way, Poonam Chandra, Maryam Modjaz +31
While the subclass of interacting supernovae with narrow hydrogen emission lines (SNe IIn) consists of some of the longest-lasting and brightest SNe ever discovered, their progenit…
Sub-arcsecond resolution imaging of M 51 with the International LOFAR Telescope
Deepika Venkattu, Peter Lundqvist, Miguel Pérez-Torres +5
We present an International LOFAR Telescope sub-arcsecond resolution image of the nearby galaxy M 51 with a beam size of 0.436" x 0.366" and rms of 46 Jy. We compare this image…
The Polarization Convention of the uGMRT in Band 4
Barnali Das, Sanjay Kudale, Poonam Chandra +3
We present an experiment performed to understand the polarization convention adopted for band 4 (550--900 MHz) of the upgraded Giant Metrewave Radio Telescope (uGMRT). For that we…
Radio and X-ray observations of SN 2006jd: Another strongly interacting Type IIn supernova
Poonam Chandra, Roger A. Chevalier, Nikolai Chugai +5
We report four years of radio and X-ray monitoring of the Type IIn supernova SN 2006jd at radio wavelengths with the Very Large Array, Giant Metrewave Radio Telescope and Expanded…
A 3D framework to explore the propagation effects in stars exhibiting electron cyclotron maser emission
Barnali Das, Surajit Mondal, Poonam Chandra
Recently, coherent radio emission has been discovered from a number of hot magnetic stars, via the process of electron cyclotron maser emission (ECME). This emission, observed in t…
First monitoring campaign of a Main-sequence Radio Pulse emitter: the case of CU Vir
Barnali Das, Hayley Bignall, Andrew Zic +6
CU Vir, a magnetic hot star, is the first discovered Main-sequence Radio Pulse emitter (MRP) characterized by its ability to produce periodic radio pulses via electron cyclotron ma…
Multidisciplinary Science in the Multimessenger Era
Eric Burns, Christopher L. Fryer, Ivan Agullo +82
Astrophysical observations of the cosmos allow us to probe extreme physics and answer foundational questions on our universe. Modern astronomy is increasingly operating under a hol…
Interpretation of Radio Afterglows in the framework of the Standard Fireball and Energy Injection models
Delina Levine, Maria Dainotti, Nissim Fraija +3
Gamma-Ray Bursts (GRBs) are panchromatic, highly energetic transients whose energy emission mechanism is still debated. One of the possible explanations is the standard fireball mo…
uGMRT observations of a Fast and Blue Optical Transient -- AT 2018cow
A. J. Nayana, Poonam Chandra
We present low-frequency radio observations of a fast-rising blue optical transient (FBOT), AT\,2018cow, with the upgraded Giant Metrewave Radio Telescope (uGMRT). Our observations…
1000 days of lowest frequency emission from the low-luminosity GRB 171205A
Barun Maity, Poonam Chandra
We report the lowest frequency measurements of gamma-ray burst (GRB) 171205A with the upgraded Giant Metrewave Radio Telescope (uGMRT) covering a frequency range from 250--1450 MHz…
The first radio view of a type Ibn supernova in SN 2023fyq: Understanding the mass-loss history in the last decade before the explosion
Raphael Baer-Way, A. J. Nayana, Wynn Jacobson-Galan +13
Supernovae that interact with hydrogen-poor, helium-rich circumstellar material (CSM), known as Type Ibn supernovae (SNe Ibn), present a unique opportunity to probe mass-loss proce…
Minutes-duration Optical Flares with Supernova Luminosities
Anna Y. Q. Ho, Daniel A. Perley, Ping Chen +74
In recent years, certain luminous extragalactic optical transients have been observed to last only a few days. Their short observed duration implies a different powering mechanism…
Radio view of a broad-line Type Ic supernova ASASSN-16fp
Nayana A. J., Poonam Chandra
We present extensive radio observations of a Type Ic supernova, ASASSN-16fp. Our data represents the lowest frequency observations of the SN beyond 1000 days with a frequency range…
ASKAP J005512.2-255834: A Luminous, Long-Lived Radio Transient at z = 0.1 -- an Orphan Afterglow or an off-nuclear TDE from an IMBH?
Ashna Gulati, Tara Murphy, David L. Kaplan +24
We report the discovery of a slowly evolving, extragalactic radio transient, ASKAP J005512.2--255834 (hereafter ASKAP J0055-2558), identified using the Australian SKA Pathfinder in…