The Nearby Luminous Transient AT2018cow: A Magnetar Formed in a Subrelativistically Expanding Nonjetted Explosion

Mohan, Prashanth; An, Tao; Yang, Jun

doi:10.3847/2041-8213/ab64d1

Cited by 39 publications

(28 citation statements)

References 33 publications

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“…AT2018cow was suggested to have two distinct components: a shock driven through dense equatorial material (producing the optical emission), and a faster polar outflow (producing the radio emission; Margutti et al 2019). As shown by early millimeter observations (Ho et al 2019b), later radio observations (Margutti et al 2019), and Very Long Baseline Interferometry (Bietenholz et al 2020;Mohan et al 2020), the fast outflow was subrelativistic with a near-constant velocity of = v c 0.1 . In ZTF18abvkwla, the radio-emitting ejecta is faster: >0.38c at the same epochs when the outflow velocity of AT2018cow was c 0.1 .…”

Section: Progenitor Systems and A Search For An Associatedmentioning

confidence: 99%

The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at z = 0.27

Ho¹,

Perley²,

Kulkarni³

et al. 2020

ApJ

100

111

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We present ZTF18abvkwla (the "Koala"), a fast blue optical transient discovered in the Zwicky Transient Facility (ZTF) One-Day Cadence (1DC) Survey. ZTF18abvkwla has a number of features in common with the groundbreaking transient AT 2018cow: blue colors at peak (-»g r 0.5 mag), a short rise time from half-max of under two days, a decay time to half-max of only three days, a high optical luminosity (»-M 20.6 g,peak mag), a hot (40,000 K) featureless spectrum at peak light, and a luminous radio counterpart. At late times (D > t 80 days), the radio luminosity of ZTF18abvkwla (n n- L 10 erg s 40 1 at 10 GHz, observer-frame) is most similar to that of long-duration gamma-ray bursts (GRBs). The host galaxy is a dwarf starburst galaxy ( »Ḿ M 5 10 8 ,  »-M SFR 7 yr 1) that is moderately metal-enriched ([ ] » log O H 8.5), similar to the hosts of GRBs and superluminous supernovae. As in AT2018cow, the radio and optical emission in ZTF18abvkwla likely arise from two separate components: the radio from fast-moving ejecta (b G > c c 0.38) and the optical from shockinteraction with confined dense material (<0.07 M e in~10 cm 15). Compiling transients in the literature with < t 5 days rise and <-M 20 peak mag, we find that a significant number are engine-powered, and suggest that the high peak optical luminosity is directly related to the presence of this engine. From 18 months of the 1DC survey, we find that transients in this rise-luminosity phase space are at least two to three orders of magnitude less common than CC SNe. Finally, we discuss strategies for identifying such events with future facilities like the Large Synoptic Survey Telescope, as well as prospects for detecting accompanying X-ray and radio emission.

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Section: Progenitor Systems and A Search For An Associatedmentioning

confidence: 99%

The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at z = 0.27

Ho¹,

Perley²,

Kulkarni³

et al. 2020

ApJ

100

111

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“…The nearby transient AT2018cow has drawn many comparisons to the cosmological RETs from DES and PS1 (e.g. Perley et al 2019;Margutti et al 2019;Fox & Smith 2019;Mohan et al 2020) due to its rapid evolution and blue colour. AT2018cow displayed a contracting photosphere as well as evidence for central-engine power alongside an unusual spectrum that showed similarities to broad-lined SNe Ic (SN Icbl) at early stages (e.g.…”

Section: Comparison With Individual Retsmentioning

confidence: 99%

“…The transient declined from its discovery, with constraints on the rise time of 1 day, and from X-rays through to radio wavelengths did not resemble any known SN, GRB afterglow, or kilonova (KN;Ho et al 2019) . There are many diverse explanations for the power source of AT2018cow touted in the literature, including: magnetars (Mohan et al 2020); electron capture collapse of merged white dwarfs (Lyutikov & Toonen 2019); a tidal disruption event (TDE) of a white dwarf (Kuin et al 2019) or of a main sequence star by an intermediate mass black hole (Perley et al 2019); common envelope jets supernova (CEJSN;Soker et al 2019); or a wind-driven transient (Uno & Maeda 2020). Other nearby rapid transients include the local fast-declining SN-like transient SN2018kzr (McBrien et al 2019) which is explained by the accretion-induced collapse of a white dwarf or a white dwarf-neutron star merger, and KSN-2015K (Rest et al 2018) whose fast rise and decline is explained by the shock of an SN running into previously-expelled material.…”

mentioning

confidence: 99%

The host galaxies of 106 rapidly evolving transients discovered by the Dark Energy Survey

Wiseman¹,

Pursiainen²,

Childress³

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Rapidly evolving transients (RETs), also termed fast blue optical transients (FBOTs), are a distinct class of astrophysical event. They are characterised by lightcurves that decline much faster than common classes supernovae (SNe), span vast ranges in peak luminosity and can be seen to redshifts greater than 1. Their evolution on fast timescales has hindered high quality follow-up observations, and thus their origin and explosion/emission mechanism remains unexplained. In this paper we define the largest sample of RETs to date, comprising 106 objects from the Dark Energy Survey, and perform the most comprehensive analysis of RET host galaxies. Using deep-stacked photometry and emission-lines from OzDES spectroscopy, we derive stellar masses and star-formation rates (SFRs) for 49 host galaxies, and metallicities for 37. We find that RETs explode exclusively in star-forming galaxies and are thus likely associated with massive stars. Comparing RET hosts to samples of host galaxies of other explosive transients as well as field galaxies, we find that RETs prefer galaxies with high specific SFRs, indicating a link to young stellar populations, similar to stripped-envelope SNe. RET hosts appear to show a lack of chemical enrichment, their metallicities akin to long duration gamma-ray bursts and superluminous SN host galaxies. There are no clear relationships between properties of the host galaxies and the peak magnitudes or decline rates of the transients themselves.

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“…The enigmatic AT 2018cow event (Prentice et al 2018) and similar FBOTs have promoted the development of several scenarios for AT 2018cow-like FBOTs (e.g., Liu et al 2018;Fox & Smith 2019;Kuin et al 2019;Lyutikov & Toonen 2019;Margutti et al 2019;Quataert, Lecoanet, & Coughlin 2019;Yu et al 2019;Leung et al 2020;Mohan, An, & Yang 2020;Piro & Lu 2020;Uno & Maeda 2020;Kremer et al 2021;Xiang et al 2021;Gottlieb, Tchekhovskoy, & Margutti 2022). In the present study I do not compare the different scenarios with each other but rather present the polar-CEJSN impostor channel (section 2) and its new ingredients (section 3).…”

Section: Introductionmentioning

confidence: 99%

A common envelope jets supernova (CEJSN) impostor scenario for fast blue optical transients

Soker

2022

Preprint

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I propose a new scenario, the polar common envelope jets supernova (CEJSN) impostor scenario, to account for AT2018cow-like fast blue optical transients (FBOTs). The polar CEJSN impostor scenario evolves through four main phases. (1) A red supergiant (RSG) star expands to tidally interact with a neutron star (NS) companion (or a black hole). The interaction increases the RSG mass loss rate to form a circumstellar matter (CSM) halo to r 0.1 pc. (2) Shortly before the onset of a common envelope evolution (CEE) and about a year before explosion the NS accretes mass from the RSG envelope and launches jets that inflate two opposite lobes in the CSM within ≈ 100 AU. (3) The NS-RSG system enters a CEE phase during which the system ejects most of the envelope mass in a dense equatorial outflow. (4) At the termination of the CEE the leftover envelope forms a circumbinary disk around the NS-core system. The NS accretes mass from the circumbinary disk and launches energetic jets that when collide with the fronts of the CSM lobes power an FBOT event. The low mass of the jets-lobes interaction zones and their large distance, of about 100 AU, from the center account for the fast transient. In the future the core collapses to form a second NS. In the far future the two NS might merge. I suggest that FBOTs and similar fast transients are CEJSN impostors which compose a large fraction of the progenitors of NS-NS merger binaries.

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The Nearby Luminous Transient AT2018cow: A Magnetar Formed in a Subrelativistically Expanding Nonjetted Explosion

Cited by 39 publications

References 33 publications

The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at z = 0.27

The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at z = 0.27

The host galaxies of 106 rapidly evolving transients discovered by the Dark Energy Survey

A common envelope jets supernova (CEJSN) impostor scenario for fast blue optical transients

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