Kishalay De

Kavli Institute for Particle Astrophysics and Cosmology

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i-10 index

Research Trends

Author Order

Document Type

Co-Authors

M. M. Kasliwal

California Institute of Technology

211

C. Fremling

California Institute of Technology

109

J. Sollerman

Stockholm University

107

D. A. Perley

Liverpool John Moores University

Igor Andreoni

Joint Space Science Institute

Frank J. Masci

California Institute of Technology

M. J. Graham

California Institute of Technology

S. R. Kulkarni

California Institute of Technology

Viraj Karambelkar

California Institute of Technology

Eric C. Bellm

University of Washington

Cooperative Institutions

California Institute of Technology

304

Cornell University

201

Alpha and Omega Semiconductor (Bermuda)

192

Advantech AMT (Canada)

191

Robert Bosch (India)

191

Renewable Energy Systems (United States)

188

Custom Electronics (United States)

187

University of California, Berkeley

103

Center for Astrophysics Harvard & Smithsonian

Centre National de la Recherche Scientifique

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Papers

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Serendipitous detection of the dusty Type IIL SN 1980K with JWST/MIRI

Szanna Zsíros Tamás Szalai I. De Looze Arkaprabha Sarangi Melissa Shahbandeh

We present mid-infrared (mid-IR) imaging of the Type IIL supernova (SN) 1980K with the James Webb Space Telescope (JWST) more than 40 yr post-explosion. SN 1980K, located in the nearby ($D\approx7$ Mpc) "SN factory" galaxy NGC 6946, was serendipitously captured in JWST/MIRI images taken of the field of SN 2004et in the same galaxy. SN 1980K serves as a promising candidate for studying the transitional phase between young SNe and older SN remnants and also provides a great opportunity to investigate its the close environment. SN 1980K can be identified as a clear and bright point source in all eight MIRI filters from F560W up to F2550W. We fit analytical dust models to the mid-IR spectral energy distribution that reveal a large amount ($M_d \approx 0.002 {M}_{\odot}$) of Si-dominated dust at $T_{dust}\approx 150$ K (accompanied by a hotter dust/gas component), and also computed numerical SED dust models. Radiative transfer modeling of a late-time optical spectrum obtained recently with Keck discloses that an even larger ($\sim 0.24-0.58~{M}_{\odot}$) amount of dust is needed in order for selective extinction to explain the asymmetric line profile shapes observed in SN 1980K. As a conclusion, with JWST, we may see i) pre-existing circumstellar dust heated collisionally (or, partly radiatively), analogous to the equatorial ring of SN 1987A, or ii) the mid-IR component of the presumed newly-formed dust, accompanied by much more colder dust present in the ejecta (as suggested by the late-time the optical spectra).

Extinction (optical mineralogy)

Spectral energy distribution

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The Zwicky Transient Facility Census of the Local Universe. I. Systematic Search for Calcium-rich Gap Transients Reveals Three Related Spectroscopic Subclasses

The Astrophysical Journal (2020)

Kishalay De M. M. Kasliwal Anastasios Tzanidakis C. Fremling S. M. Adams

(Abridged) Using the Zwicky Transient Facility alert stream, we are conducting a large campaign to spectroscopically classify all transients occurring in galaxies in the Census of the Local Universe (CLU) catalog. The aim of the experiment is to construct a spectroscopically complete, volume-limited sample of transients coincident within 100" of CLU galaxies out to 200 Mpc, and to a depth of 20 mag. We describe the survey design and spectroscopic completeness from the first 16 months of operations. We present results from a systematic search for Calcium rich gap transients in the sample of 22 low luminosity (peak absolute magnitude $M > -17$), hydrogen poor events found in the experiment (out of 754 spectroscopically classified SNe). We report the detection of eight Calcium rich gap transients, and constrain their volumetric rate to be at least $\approx 15\pm5$% of the SN Ia rate. Combining this sample with ten events from the literature, we find a likely continuum of spectroscopic properties ranging from events with SN Ia-like features (Ca-Ia objects) to SN Ib/c-like features (Ca-Ib/c objects) at peak light. Within the Ca-Ib/c events, we find two populations of events distinguished by their red ($g - r \approx 1.5$ mag) or green ($g - r \approx 0.5$ mag) spectral colors at $r$-band peak, wherein redder events show strong line blanketing signatures, slower light curves, weaker He lines and lower [Ca II]/[O I] in the nebular phase. Together, we find that the spectroscopic continuum, volumetric rates and striking old environments are consistent with the explosive burning of He shells on low mass white dwarfs. We posit that Ca-Ia and red Ca-Ib/c objects are consistent with the double detonation of He shells with high He burning efficiency, while green Ca-Ib/c objects could arise from less efficient He burning scenarios such as detonations in low density He shells or He shell deflagrations.

Blanketing

10.3847/1538-4357/abb45c

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SN2019dge: A Helium-rich Ultra-stripped Envelope Supernova

The Astrophysical Journal (2020)

Yuhan Yao Kishalay De M. M. Kasliwal Anna Y. Q. Ho S. Schulze

We present observations of ZTF18abfcmjw (SN2019dge), a helium-rich supernova with a fast-evolving light curve indicating an extremely low ejecta mass ($\approx 0.3\,M_\odot$) and low kinetic energy ($\approx 1.2\times 10^{50}\,{\rm erg}$). Early-time (<4 d after explosion) photometry reveal evidence of shock cooling from an extended helium-rich envelope of $\sim0.1\,M_\odot$ located at $\sim 3\times 10^{12}\,{\rm cm}$ from the progenitor. Early-time He II line emission and subsequent spectra show signatures of interaction with helium-rich circumstellar material, which extends from $\gtrsim 5\times 10^{13}\,{\rm cm}$ to $\gtrsim 2\times 10^{16}\,{\rm cm}$. We interpret SN2019dge as a helium-rich supernova from an ultra-stripped progenitor, which originates from a close binary system consisting of a mass-losing helium star and a low-mass main sequence star or a compact object (i.e., a white dwarf, a neutron star, or a black hole). We infer that the local volumetric birth rate of 19dge-like ultra-stripped SNe is in the range of 1400--8200$\,{\rm Gpc^{-3}\, yr^{-1}}$ (i.e., 2--12% of core-collapse supernova rate). This can be compared to the observed coalescence rate of compact neutron star binaries that are not formed by dynamical capture.

10.3847/1538-4357/abaa3d

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An ASKAP Search for a Radio Counterpart to the First High-significance Neutron Star–Black Hole Merger LIGO/Virgo S190814bv

The Astrophysical Journal Letters (2019)

Dougal Dobie A. Stewart Tara Murphy E. Lenc Ziteng Wang

Abstract We present results from a search for a radio transient associated with the LIGO/Virgo source S190814bv, a likely neutron star–black hole (NSBH) merger, with the Australian Square Kilometre Array Pathfinder. We imaged a 30 deg 2 field at Δ T = 2, 9, and 33 days post-merger at a frequency of 944 MHz, comparing them to reference images from the Rapid ASKAP Continuum Survey observed 110 days prior to the event. Each epoch of our observations covers 89% of the LIGO/Virgo localization region. We conducted an untargeted search for radio transients in this field, resulting in 21 candidates. For one of these, AT2019osy, we performed multiwavelength follow-up and ultimately ruled out the association with S190814bv. All other candidates are likely unrelated variables, but we cannot conclusively rule them out. We discuss our results in the context of model predictions for radio emission from NSBH mergers and place constrains on the circum-merger density and inclination angle of the merger. This survey is simultaneously the first large-scale radio follow-up of an NSBH merger, and the most sensitive widefield radio transients search to-date.

Black hole (networking)

Pathfinder

10.3847/2041-8213/ab59db

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pinta: The uGMRT data processing pipeline for the Indian Pulsar Timing Array

Publications of the Astronomical Society of Australia (2021)

Abhimanyu Susobhanan Yogesh Maan B. C. Joshi T. Prabu S. Desai

Abstract We introduce pinta , a pipeline for reducing the upgraded Giant Metre-wave Radio Telescope (uGMRT) raw pulsar timing data, developed for the Indian Pulsar Timing Array experiment. We provide a detailed description of the workflow and usage of pinta , as well as its computational performance and RFI mitigation characteristics. We also discuss a novel and independent determination of the relative time offsets between the different back-end modes of uGMRT and the interpretation of the uGMRT observation frequency settings and their agreement with results obtained from engineering tests. Further, we demonstrate the capability of pinta to generate data products which can produce high-precision TOAs using PSR J1909 $-$ 3744 as an example. These results are crucial for performing precision pulsar timing with the uGMRT.

10.1017/pasa.2021.12

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Four (Super)luminous Supernovae from the First Months of the ZTF Survey

The Astrophysical Journal (2020)

R. Lunnan Lin Yan D. A. Perley S. Schulze K. Taggart

Abstract We present photometry and spectroscopy of four hydrogen-poor luminous supernovae discovered during the 2-month long science commissioning and early operations of the Zwicky Transient Facility (ZTF) survey. Three of these objects, SN 2018bym (ZTF18aapgrxo), SN 2018avk (ZTF18aaisyyp), and SN 2018bgv (ZTF18aavrmcg), resemble typical SLSN-I spectroscopically, while SN 2018don (ZTF18aajqcue) may be an object similar to SN 2007bi experiencing considerable host galaxy reddening, or an intrinsically long-lived, luminous, and red SN Ic. We analyze the light curves, spectra, and host galaxy properties of these four objects and put them in context of the population of SLSN-I. SN 2018bgv stands out as the fastest-rising SLSN-I observed to date, with a rest-frame g -band rise time of just 10 days from explosion to peak—if it is powered by magnetar spin-down, the implied ejecta mass is only ≃1 M ⊙ . SN 2018don also displays unusual properties—in addition to its red colors and comparatively massive host galaxy, the light curve undergoes some of the strongest light-curve undulations postpeak seen in an SLSN-I, which we speculate may be due to interaction with circumstellar material. We discuss the promises and challenges of finding SLSNe in large-scale surveys like ZTF given the observed diversity in the population.

10.3847/1538-4357/abaeec

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Citations (14)

A Strong Jet Signature in the Late-time Light Curve of GW170817

The Astrophysical Journal Letters (2018)

K. P. Mooley D. A. Frail Dougal Dobie E. Lenc A. Corsi

Abstract We present new 0.6–10 GHz observations of the binary neutron star merger GW170817 covering the period up to 300 days post-merger, taken with the upgraded Karl G. Jansky Very Large Array, the Australia Telescope Compact Array, the Giant Metrewave Radio Telescope and the MeerKAT telescope. We use these data to precisely characterize the decay phase of the late-time radio light curve. We find that the temporal decay is consistent with a power-law slope of t −2.2 , and that the transition between the power-law rise and decay is relatively sharp. Such a slope cannot be produced by a quasi-isotropic (cocoon-dominated) outflow, but is instead the classic signature of a relativistic jet. This provides strong observational evidence that GW170817 produced a successful jet, and directly demonstrates the link between binary neutron star mergers and short-hard gamma-ray bursts. Using simple analytical arguments, we derive constraints on the geometry and the jet opening angle of GW170817. These results are consistent with those from our companion very long baseline interferometry paper, reporting superluminal motion in GW170817.

Superluminal motion

Jansky

Very-long-baseline interferometry

10.3847/2041-8213/aaeda7

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Citations (129)

LIGO/Virgo S191205ah: Candidates from the Zwicky Transient Facility Public Survey

GRB Coordinates Network (2019)

Igor Andreoni Shreya Anand M. W. Coughlin Kishalay De M. M. Kasliwal

Transient (computer programming)

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Palomar Gattini-IR discovery of a peculiar, rapidly rising and highly reddened Galactic transient PGIR21fjn/AT2021kgk

Transient Name Server AstroNote (2021)

R. Soria Kishalay De M. M. Kasliwal K. S. Tinyanont Ryan M. Lau

Transient (computer programming)

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An exceptional infrared transient from a star engulfing a planet

Research Square (Research Square) (2022)

Kishalay De Morgan MacLeod Viraj Karambelkar J. Jencson Deepto Chakrabarty

Abstract It is well known that planets with short orbital periods (< 10 days) are common around stars like the Sun. Stars expand as they evolve, and thus we expect their close planetary companions to be engulfed. However, this phase has never been directly observed. Here, we present the discovery of ZTF SLRN-2020, a short-lived optical outburst in the Galactic disk accompanied by bright and long-lived infrared emission. The resulting light curve and spectra share striking similarities with those of red novae -- a class of eruptions now confirmed to arise from mergers of binary stars. Its exceptionally low optical luminosity (10^{35} erg/s) and radiated energy (6.5 X 10^{41} erg) point to the engulfment of a planet (of 1 - 10 Jupiter masses) by its Sun-like host star. We estimate the Galactic rate of such Sub-luminous Red Novae (SLRNe) to be $\sim 0.1 - few per year. Future Galactic plane surveys are well-poised to routinely identify them, revealing the demographics of planetary engulfment and the ultimate fate of planets in the inner Solar System.

10.21203/rs.3.rs-2117913/v1

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