Dr Shubham Srivastav: Publications

Characterizing the Rapid Hydrogen Disappearance in SN 2022crv: Evidence of a Continuum between Type Ib and IIb Supernova Properties

The Astrophysical Journal American Astronomical Society 974:2 (2024) 316

Authors:

Yize Dong, Stefano Valenti, Chris Ashall, Marc Williamson, David J Sand, Schuyler D Van Dyk, Alexei V Filippenko, Saurabh W Jha, Michael Lundquist, Maryam Modjaz, Jennifer E Andrews, Jacob E Jencson, Griffin Hosseinzadeh, Jeniveve Pearson, Lindsey A Kwok, Teresa Boland, Eric Y Hsiao, Nathan Smith, Nancy Elias-Rosa, Shubham Srivastav, Stephen Smartt, Michael Fulton, WeiKang Zheng, Thomas G Brink, Melissa Shahbandeh, K Azalee Bostroem, Emily Hoang, Daryl Janzen, Darshana Mehta, Nicolas Meza, Manisha Shrestha, Samuel Wyatt, Katie Auchettl, Christopher R Burns, Joseph Farah, Lluís Galbany, Estefania Padilla Gonzalez, Joshua Haislip, Jason T Hinkle, D Andrew Howell, Thomas De Jaeger, Vladimir Kouprianov, Sahana Kumar, Jing Lu, Curtis McCully, Shane Moran, Nidia Morrell, Megan Newsome, Craig Pellegrino, Abigail Polin, Daniel E Reichart, BJ Shappee, Maximilian D Stritzinger, Giacomo Terreran, MA Tucker

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SN 2021dbg: A Luminous Type IIP–IIL Supernova Exploding from a Massive Star with a Layered Shell

The Astrophysical Journal American Astronomical Society 973:2 (2024) 155-155

Authors:

Zeyi Zhao, Jujia Zhang, Liping Li, Qian Zhai, Yongzhi Cai, Shubham Srivastav, Xiaofeng Wang, Han Lin, Yi Yang, Alexei V Filippenko, Thomas G Brink, WeiKang Zheng

Abstract:

Abstract We present extensive observations and analysis of supernova (SN) SN 2021dbg, utilizing optical photometry and spectroscopy. For approximately 385 days following the explosion, SN 2021dbg exhibited remarkable luminosity, surpassing most Type II SNe (SNe II). This initial high luminosity is potentially attributed to interaction between the ejected material and the surrounding circumstellar material (CSM), as evidenced by the pronounced interaction signatures observed in its spectra. The subsequent high luminosity is primarily due to the significant 56Ni mass (0.17 ± 0.05 M ⊙) produced in the explosion. Based on the flux of flash emission lines detected in the initial spectra, we estimate that the CSM mass near the progenitor amounted to ∼(1.0–2.0) × 10−3 M ⊙, likely resulting from intense stellar wind activity 2–3 yr preceding the explosion. Considering the bolometric light curve, nebular spectrum modeling, and mass-loss rate, we suggest that the progenitor of SN 2021dbg was a red supergiant (RSG) with a mass of ∼20 M ⊙ and a radius of 1200 R ⊙. This RSG featured a thick hydrogen shell, which may have contained a region with a sharp decrease in material density, electron density, and temperature, contributing to its layered structure. This object demonstrates mixed features of Type IIP and IIL SNe, making it a transitional event linking the above two subclasses of SNe II.

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Identification of the optical counterpart of the fast X-ray transient EP240414a

ArXiv 2409.1907 (2024)

Authors:

S Srivastav, T-W Chen, JH Gillanders, L Rhodes, SJ Smartt, ME Huber, A Aryan, S Yang, A Beri, AJ Cooper, M Nicholl, KW Smith, HF Stevance, F Carotenuto, KC Chambers, A Aamer, CR Angus, MD Fulton, T Moore, IA Smith, DR Young, T de Boer, H Gao, C-C Lin, T Lowe, EA Magnier, P Minguez, Y-C Pan, RJ Wainscoat

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Quasi-periodic X-ray eruptions years after a nearby tidal disruption event

(2024)

Authors:

M Nicholl, DR Pasham, A Mummery, M Guolo, K Gendreau, GC Dewangan, EC Ferrara, R Remillard, C Bonnerot, J Chakraborty, A Hajela, VS Dhillon, AF Gillan, J Greenwood, ME Huber, A Janiuk, G Salvesen, S van Velzen, A Aamer, KD Alexander, CR Angus, Z Arzoumanian, K Auchettl, E Berger, T de Boer, Y Cendes, KC Chambers, T-W Chen, R Chornock, MD Fulton, H Gao, JH Gillanders, S Gomez, BP Gompertz, AC Fabian, J Herman, A Ingram, E Kara, T Laskar, A Lawrence, C-C Lin, TB Lowe, EA Magnier, R Margutti, SL McGee, P Minguez, T Moore, E Nathan, SR Oates, KC Patra, P Ramsden, V Ravi, EJ Ridley, X Sheng, SJ Smartt, KW Smith, S Srivastav, R Stein, HF Stevance, SGD Turner, RJ Wainscoat, J Weston, T Wevers, DR Young

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On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae – II. 3D synthetic observables

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 533:3 (2024) 3036-3052

Authors:

JM Pollin, SA Sim, R Pakmor, FP Callan, CE Collins, LJ Shingles, FK Röpke, S Srivastav

Abstract:

ABSTRACT A leading model for Type Ia supernovae involves the double-detonation of a sub-Chandrasekhar mass white dwarf. Double-detonations arise when a surface helium shell detonation generates shockwaves that trigger a core detonation; this mechanism may be triggered via accretion or during the merger of binaries. Most previous double-detonation simulations only included the primary white dwarf; however, the fate of the secondary has significant observational consequences. Recently, hydrodynamic simulations accounted for the companion in double-degenerate double-detonation mergers. In the merger of a 1.05 M$_{\odot }$ primary white dwarf and 0.7 M$_{\odot }$ secondary white dwarf, the primary consistently detonates while the fate of the secondary remains uncertain. We consider two versions of this scenario, one in which the secondary survives and another in which it detonates. We present the first 3D radiative transfer calculations for these models and show that the synthetic observables for both models are similar and match properties of the peculiar 02es-like subclass of Type Ia supernovae. Our calculations show angle dependencies sensitive to the companion’s fate, and we can obtain a closer spectroscopic match to normal Type Ia supernovae when the secondary detonates and the effects of helium detonation ash are minimized. The asymmetry in the width–luminosity relationship is comparable to previous double-detonation models, but the overall spread is increased with a secondary detonation. The secondary detonation has a meaningful impact on all synthetic observables; however, multidimensional nebular phase calculations are needed to support or rule out either model as a likely explanation for Type Ia supernovae.

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Dr Shubham Srivastav

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Characterizing the Rapid Hydrogen Disappearance in SN 2022crv: Evidence of a Continuum between Type Ib and IIb Supernova Properties

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SN 2021dbg: A Luminous Type IIP–IIL Supernova Exploding from a Massive Star with a Layered Shell

Authors:

Abstract:

Identification of the optical counterpart of the fast X-ray transient EP240414a

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Quasi-periodic X-ray eruptions years after a nearby tidal disruption event

Authors:

On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae – II. 3D synthetic observables

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Abstract:

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Dr Shubham Srivastav

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Characterizing the Rapid Hydrogen Disappearance in SN 2022crv: Evidence of a Continuum between Type Ib and IIb Supernova Properties

Authors:

SN 2021dbg: A Luminous Type IIP–IIL Supernova Exploding from a Massive Star with a Layered Shell

Authors:

Abstract:

Identification of the optical counterpart of the fast X-ray transient EP240414a

Authors:

Quasi-periodic X-ray eruptions years after a nearby tidal disruption event

Authors:

On the fate of the secondary white dwarf in double-degenerate double-detonation Type Ia supernovae – II. 3D synthetic observables

Authors:

Abstract: