Broad-line type Ic SN 2020bvc:Signatures of an off-axis gamma-ray burst afterglow
Autor: | Enrico Ramirez-Ruiz, F. De Colle, S. I. Raimundo, Jens Hjorth, Luca Izzo, Katie Auchettl, Christa Gall, C. R. Angus |
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Jazyk: | angličtina |
Rok vydání: | 2020 |
Předmět: |
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Radiation general [gamma-ray burst] 01 natural sciences GRB-060218 law.invention Telescope Observatory law 0103 physical sciences SPECTRA RATES 010303 astronomy & astrophysics SUPERNOVA Line (formation) High Energy Astrophysical Phenomena (astro-ph.HE) Physics LIGHT CURVES 010308 nuclear & particles physics COCOON individual: SN2020bvc [supernovae] Astronomy and Astrophysics Optical spectra EVOLUTION Afterglow MODEL Supernova jets [stars] Space and Planetary Science JETS Astrophysics - High Energy Astrophysical Phenomena Gamma-ray burst EMISSION |
Zdroj: | Izzo, L, Auchettl, K, Hjorth, J, De Colle, F, Gall, C, Angus, C R, Raimundo, S & Ramirez-Ruiz, E 2020, ' Broad-line type Ic SN 2020bvc : Signatures of an off-axis gamma-ray burst afterglow ', Astronomy & Astrophysics, vol. 639, L11 . https://doi.org/10.1051/0004-6361/202038152 |
Popis: | Long-duration gamma-ray bursts (GRBs) are almost unequivocally associated with very energetic, broad-lined supernovae (SNe) of Type Ic-BL. While the gamma-ray emission is emitted in narrow jets, the SN emits radiation isotropically. Therefore, some SN Ic-BL not associated with GRBs have been hypothesized to arise from events with inner engines such as off-axis GRBs or choked jets. Here we present observations of the nearby ($d = 120$ Mpc) SN 2020bvc (ASAS-SN 20bs) which support this scenario. \textit{Swift} UVOT observations reveal an early decline (up to two days after explosion) while optical spectra classify it as a SN Ic-BL with very high expansion velocities ($\approx$ 70,000 km/s), similar to that found for the jet-cocoon emission in SN 2017iuk associated with GRB 171205A. Moreover, \textit{Swift} X-Ray Telescope and \textit{CXO} X-ray Observatory detected X-ray emission only three days after the SN and decaying onwards, which can be ascribed to an afterglow component. Cocoon and X-ray emission are both signatures of jet-powered GRBs. In the case of SN 2020bvc, we find that the jet is off axis (by $\approx$ 23 degrees), as also indicated by the lack of early ($\approx 1$ day) X-ray emission which explains why no coincident GRB was detected promptly or in archival data. These observations suggest that SN 2020bvc is the first orphan GRB detected through its associated SN emission. 9 pages, 6 figures, 5 tables. Accepted for publication in A&A |
Databáze: | OpenAIRE |
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