Radio and X-Ray Observations of the Luminous Fast Blue Optical Transient AT 2020xnd

Bright, J. S.; Margutti, R.; Matthews, D. J.; Brethauer, Daniel; Coppejans, D. L.; Wieringa, M.; Metzger, Brian; DeMarchi, L. M.; Laskar, T.; Romero, C.; Alexander, K. D.; Horesh, A.; Migliori, G.; Chornock, R.; Berger, E.; Bietenholz, M. F.; Devlin, Mark J.; Dicker, Simon; Jacobson-Galán, W. V.; Mason, B. S.; Milisavljevic, Dan; Motta, S.; Mroczkowski, Tony; Ramírez-Ruiz, E.; Rhodes, L.; Sarazin, Craig L.; Sfaradi, Itai; Sievers, Jonathan

doi:10.3847/1538-4357/ac4506

Cited by 43 publications

(40 citation statements)

References 60 publications

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“…CSS161010 (Coppejans et al 2020) and AT2018lug ("Koala"; Ho et al 2020) exhibited broadly similar optical and radio emission to AT2018cow, but with even higher peak ejecta speeds v  0.55c and v  0.38c, respectively. AT2020xnd showed broadly similar optical, X-ray, and millimeter radio emission to AT2018cow, including the abrupt decrease in the X-ray luminosity around 1 month after the start of the explosion (Ho et al 2021a;Perley et al 2021;Bright et al 2022). The radio emission from AT2020xnd also showed evidence for a steep cutoff n∝r −3 in the CSM density at r ∼ 3 × 10 16 cm (Ho et al 2021a;Bright et al 2022), incompatible with that of a steady pre-explosion wind (n ∝ r −2 ).…”

Section: Lessons From At2018cow and Its Analogsmentioning

confidence: 76%

“…AT2020xnd showed broadly similar optical, X-ray, and millimeter radio emission to AT2018cow, including the abrupt decrease in the X-ray luminosity around 1 month after the start of the explosion (Ho et al 2021a;Perley et al 2021;Bright et al 2022). The radio emission from AT2020xnd also showed evidence for a steep cutoff n∝r −3 in the CSM density at r ∼ 3 × 10 16 cm (Ho et al 2021a;Bright et al 2022), incompatible with that of a steady pre-explosion wind (n ∝ r −2 ). AT2020mrf exhibited optical and radio emission similar to AT2018cow, but showed variable X-ray emission a factor 200 times more luminous than AT2018cow at a comparable epoch (Yao et al 2021).…”

Section: Lessons From At2018cow and Its Analogsmentioning

confidence: 76%

“…However, as already noted, the coupled behavior and similar late-time luminosities of the optical and X-ray light curves in AT2018cow favors reprocessed engine power instead of shock interaction as the dominant source of optical emission. Furthermore, multiple PPI eruptions may be required to generate the large CSM mass covering radii ∼10 14 -10 16 cm (potentially requiring a fine-tuned progenitor star mass), despite a broadly similar CSM density field now inferred to characterize multiple members of the LFBOT class (Ho et al 2019(Ho et al , 2021aBright et al 2022). The low polar ejecta mass M fast  0.1M e that enables soft X-rays to escape from the central engine (Margutti et al 2019), is also in tension with the large ejecta masses predicted from the successful explosion of a ∼40M e PPISN progenitor.…”

Section: Progenitor Modelsmentioning

confidence: 99%

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Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers

Metzger

2022

ApJ

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Progenitor models for the “luminous” subclass of Fast Blue Optical Transients (LFBOTs; prototype: AT2018cow) are challenged to simultaneously explain all of their observed properties: fast optical rise times of days or less; peak luminosities ≳1044 erg s−1; low yields ≲0.1M ⊙ of 56Ni; aspherical ejecta with a wide velocity range (≲3000 km s−1 to ≳0.1–0.5c with increasing polar latitude); presence of hydrogen-depleted-but-not-free dense circumstellar material (CSM) on radial scales from ∼1014 cm to ∼3 × 1016 cm; embedded variable source of non-thermal X-ray/γ-rays, suggestive of a compact object. We show that all of these properties are consistent with the tidal disruption and hyper-accretion of a Wolf-Rayet (WR) star by a black hole or neutron star binary companion. In contrast with related previous models, the merger occurs with a long delay (≳100 yr) following the common envelope (CE) event responsible for birthing the binary, as a result of gradual angular momentum loss to a relic circumbinary disk. Disk-wind outflows from the merger-generated accretion flow generate the 56Ni-poor aspherical ejecta with the requisite velocity range. The optical light curve is powered primarily by reprocessing X-rays from the inner accretion flow/jet, though CSM shock interaction also contributes. Primary CSM sources include WR mass loss from the earliest stages of the merger (≲1014 cm) and the relic CE disk and its photoevaporation-driven wind (≳1016 cm). Longer delayed mergers may instead give rise to supernovae Type Ibn/Icn (depending on the WR evolutionary state), connecting these transient classes with LFBOTs.

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Section: Lessons From At2018cow and Its Analogsmentioning

confidence: 76%

Section: Lessons From At2018cow and Its Analogsmentioning

confidence: 76%

Section: Progenitor Modelsmentioning

confidence: 99%

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Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers

Metzger

2022

ApJ

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“…AT2018cow (Perley et al 2019;Margutti et al 2019) and CSS161010 (Coppejans et al 2020). Moreover, combined observations in the optical and radio bands suggest that the fastest component of the outflow is moving with speed 0.1c v f 0.6c (Perley et al 2019;Ho et al 2019;Margutti et al 2019;Yao et al 2021;Bright et al 2022).…”

Section: Introductionmentioning

confidence: 97%

“…LFBOTs have been detected in the hard X-ray band as well, though not yet in gamma-rays (i.e. with energies > 200 keV) (Ho et al 2019;Margutti et al 2019;Coppejans et al 2020;Ho et al 2020;Yao et al 2021;Bright et al 2022).…”

Section: Introductionmentioning

confidence: 99%

Looking at Luminous Fast Blue Optical Transients through Neutrino Glasses

Guarini,

Tamborra,

Margutti

2022

Preprint

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Mounting evidence suggests that Luminous Fast Blue Optical Transients (LFBOTs) are powered by a compact object, launching an asymmetric and fast outflow responsible for the radiation observed in the ultraviolet, optical, infrared, radio, and X-ray bands. Proposed scenarios aiming to explain the electromagnetic emission include an inflated cocoon, surrounding a jet choked in the extended stellar envelope. In alternative, the observed radiation may arise from the disk formed by the delayed merger of a black hole with a Wolf-Rayet star. We explore the neutrino production in these scenarios, i.e. internal shocks in a choked jet and interaction between the outflow and the circumstellar medium (CSM). The choked jet provides the dominant contribution to the neutrino fluence. Intriguingly, the IceCube upper limit on the neutrino emission inferred from the closest LF-BOT, AT2018cow, excludes a region of the parameter space otherwise allowed by electromagnetic observations. After correcting for the Eddington bias on the observation of cosmic neutrinos, we conclude that the emission from a choked jet and CSM interaction is compatible with the detection of two track-like neutrino events observed by the IceCube Neutrino Observatory in coincidence with AT2018cow, and otherwise considered to be of atmospheric origin. While the neutrino emission from LFBOTs does not constitute the bulk of the diffuse background of neutrinos observed by IceCube, detection prospects of nearby LFBOTs with IceCube and the upcoming IceCube-Gen2 are encouraging; neutrinos could be observed up to 300 Mpc and 10 4 Mpc from the CSM interaction and choked jet, respectively. Follow-up neutrino searches will be crucial for unravelling the mechanism powering this emergent transient class.

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Precise measurements of self-absorbed rising reverse shock emission from gamma-ray burst 221009A

et al. 2023

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The deaths of massive stars are sometimes accompanied by the launch of highly relativistic and collimated jets. If the jet is pointed towards Earth, we observe a ‘prompt’ gamma-ray burst due to internal shocks or magnetic reconnection events within the jet, followed by a long-lived broadband synchrotron afterglow as the jet interacts with the circumburst material. While there is solid observational evidence that emission from multiple shocks contributes to the afterglow signature, detailed studies of the reverse shock, which travels back into the explosion ejecta, are hampered by a lack of early-time observations, particularly in the radio band. We present rapid follow-up radio observations of the exceptionally bright gamma-ray burst GRB 221009A that reveal in detail, both temporally and in frequency space, an optically thick rising component from the reverse shock. From this, we are able to constrain the size, Lorentz factor and internal energy of the outflow while providing accurate predictions for the location of the peak frequency of the reverse shock in the first few hours after the burst. These observations challenge standard gamma-ray burst models describing reverse shock emission.

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Radio and X-Ray Observations of the Luminous Fast Blue Optical Transient AT 2020xnd

Cited by 43 publications

References 60 publications

Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers

Luminous Fast Blue Optical Transients and Type Ibn/Icn SNe from Wolf-Rayet/Black Hole Mergers

Looking at Luminous Fast Blue Optical Transients through Neutrino Glasses

Precise measurements of self-absorbed rising reverse shock emission from gamma-ray burst 221009A

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