Broad-line type Ic SN 2020bvc: Signatures of an off-axis gamma-ray burst afterglow
Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Standard
Broad-line type Ic SN 2020bvc : Signatures of an off-axis gamma-ray burst afterglow. / Izzo, L.; Auchettl, K.; Hjorth, J.; De Colle, F.; Gall, C.; Angus, C. R.; Raimundo, S.; Ramirez-Ruiz, E.
I: Astronomy & Astrophysics, Bind 639, L11, 21.07.2020.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
Harvard
APA
Vancouver
Author
Bibtex
}
RIS
TY - JOUR
T1 - Broad-line type Ic SN 2020bvc
T2 - Signatures of an off-axis gamma-ray burst afterglow
AU - Izzo, L.
AU - Auchettl, K.
AU - Hjorth, J.
AU - De Colle, F.
AU - Gall, C.
AU - Angus, C. R.
AU - Raimundo, S.
AU - Ramirez-Ruiz, E.
PY - 2020/7/21
Y1 - 2020/7/21
N2 - Long-duration gamma-ray bursts (GRBs) are almost unequivocally associated with very energetic, broad-line supernovae of Type Ic-BL. While the gamma-ray emission is emitted in narrow jets, the SN emits radiation isotropically. Therefore, it has been hypothesized that some SN Ic-BL not associated with GRBs 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) that support this scenario. 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 (approximate to 70 000 km s(-1)), similar to that found for the jet-cocoon emission in SN 2017iuk associated with GRB 171205A. Moreover, the Swift X-Ray Telescope and CXO X-ray Observatory detected X-ray emission only three days after the SN and decaying onward, 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 approximate to 23 degrees), as also indicated by the lack of early (approximate to 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.
AB - Long-duration gamma-ray bursts (GRBs) are almost unequivocally associated with very energetic, broad-line supernovae of Type Ic-BL. While the gamma-ray emission is emitted in narrow jets, the SN emits radiation isotropically. Therefore, it has been hypothesized that some SN Ic-BL not associated with GRBs 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) that support this scenario. 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 (approximate to 70 000 km s(-1)), similar to that found for the jet-cocoon emission in SN 2017iuk associated with GRB 171205A. Moreover, the Swift X-Ray Telescope and CXO X-ray Observatory detected X-ray emission only three days after the SN and decaying onward, 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 approximate to 23 degrees), as also indicated by the lack of early (approximate to 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.
KW - gamma-ray burst: general
KW - supernovae: individual: SN2020bvc
KW - stars: jets
KW - LIGHT CURVES
KW - SUPERNOVA
KW - EVOLUTION
KW - JETS
KW - EMISSION
KW - COCOON
KW - GRB-060218
KW - SPECTRA
KW - MODEL
KW - RATES
U2 - 10.1051/0004-6361/202038152
DO - 10.1051/0004-6361/202038152
M3 - Journal article
VL - 639
JO - Astronomy & Astrophysics
JF - Astronomy & Astrophysics
SN - 0004-6361
M1 - L11
ER -
ID: 246780164