GRB 221009A: The BOAT Burns, Eric; Svinkin, Dmitry; Fenimore, Edward ...
Astrophysical journal. Letters,
03/2023, Volume:
946, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract GRB 221009A has been referred to as the brightest of all time (BOAT). We investigate the veracity of this statement by comparing it with a half century of prompt gamma-ray burst ...observations. This burst is the brightest ever detected by the measures of peak flux and fluence. Unexpectedly, GRB 221009A has the highest isotropic-equivalent total energy ever identified, while the peak luminosity is at the ∼99th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultralong and high-redshift gamma-ray bursts. By geometric extrapolation of the total fluence and peak flux distributions, GRB 221009A appears to be a once-in-10,000-year event. Thus, it is almost certainly not the BOAT over all of cosmic history; it may be the brightest gamma-ray burst since human civilization began.
Abstract GW230529 is the first compact binary coalescence detected by the LIGO–Virgo–KAGRA collaboration with at least one component mass confidently in the lower mass gap, corresponding to the range ...3–5 M ⊙ . If interpreted as a neutron star–black hole merger, this event has the most symmetric mass ratio detected so far and therefore has a relatively high probability of producing electromagnetic (EM) emission. However, no EM counterpart has been reported. At the merger time t 0 , Swift-BAT and Fermi-GBM together covered 100% of the sky. Performing a targeted search in a time window t 0 − 20 s, t 0 + 20 s, we report no detection by the Swift-BAT and Fermi-GBM instruments. Combining the position-dependent γ -ray flux upper limits and the gravitational-wave posterior distribution of luminosity distance, sky localization, and inclination angle of the binary, we derive constraints on the characteristic luminosity and structure of the jet possibly launched during the merger. Assuming a top-hat jet structure, we exclude at 90% credibility the presence of a jet that has at the same time an on-axis isotropic luminosity ≳10 48 erg s −1 in the bolometric band 1 keV–10 MeV and a jet opening angle ≳15°. Similar constraints are derived by testing other assumptions about the jet structure profile. Excluding GRB 170817A, the luminosity upper limits derived here are below the luminosity of any GRB observed so far.
GW230529 is the first compact binary coalescence detected by the
LIGO-Virgo-KAGRA collaboration with at least one component mass confidently in
the lower mass-gap, corresponding to the range ...3-5$M_{\odot}$. If interpreted
as a neutron star-black hole merger, this event has the most symmetric mass
ratio detected so far and therefore has a relatively high probability of
producing electromagnetic (EM) emission. However, no EM counterpart has been
reported. At the merger time $t_0$, Swift-BAT and Fermi-GBM together covered
100$\%$ of the sky. Performing a targeted search in a time window $t_0-20
\text{s},t_0+20 \text{s}$, we report no detection by the Swift-BAT and the
Fermi-GBM instruments. Combining the position-dependent $\gamma-$ray flux upper
limits and the gravitational-wave posterior distribution of luminosity
distance, sky localization and inclination angle of the binary, we derive
constraints on the characteristic luminosity and structure of the jet possibly
launched during the merger. Assuming a top-hat jet structure, we exclude at
90$\%$ credibility the presence of a jet which has at the same time an on-axis
isotropic luminosity $\gtrsim 10^{48}$ erg s$^{-1}$, in the bolometric band 1
keV-10 MeV, and a jet opening angle $\gtrsim 15$ deg. Similar constraints are
derived testing other assumptions about the jet structure profile. Excluding
GRB 170817A, the luminosity upper limits derived here are below the luminosity
of any GRB observed so far.
GW230529 is the first compact binary coalescence detected by the LIGO-Virgo-KAGRA collaboration with at least one component mass confidently in the lower mass-gap, corresponding to the range ...3-5\(M_{\odot}\). If interpreted as a neutron star-black hole merger, this event has the most symmetric mass ratio detected so far and therefore has a relatively high probability of producing electromagnetic (EM) emission. However, no EM counterpart has been reported. At the merger time \(t_0\), Swift-BAT and Fermi-GBM together covered 100\(\%\) of the sky. Performing a targeted search in a time window \(t_0-20 \text{s},t_0+20 \text{s}\), we report no detection by the Swift-BAT and the Fermi-GBM instruments. Combining the position-dependent \(\gamma-\)ray flux upper limits and the gravitational-wave posterior distribution of luminosity distance, sky localization and inclination angle of the binary, we derive constraints on the characteristic luminosity and structure of the jet possibly launched during the merger. Assuming a top-hat jet structure, we exclude at 90\(\%\) credibility the presence of a jet which has at the same time an on-axis isotropic luminosity \(\gtrsim 10^{48}\) erg s\(^{-1}\), in the bolometric band 1 keV-10 MeV, and a jet opening angle \(\gtrsim 15\) deg. Similar constraints are derived testing other assumptions about the jet structure profile. Excluding GRB 170817A, the luminosity upper limits derived here are below the luminosity of any GRB observed so far.
