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.
Abstract
Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor Γ
init
below the Γ
init
∼ 100 required to produce a long-duration gamma-ray ...burst (LGRB), but which could still produce optical emission resembling LGRB afterglows. Here we present the results of a search for on-axis optical afterglows using the Zwicky Transient Facility (ZTF). Our search yielded seven optical transients that resemble on-axis LGRB afterglows in terms of their red colors (
g
−
r
> 0 mag), faint host galaxies (
r
> 23 mag), rapid fading (
dr
/
dt
> 1 mag day
−1
), and in some cases X-ray and radio emission. Spectroscopy of the transient emission within a few days of discovery established cosmological distances (redshift
z
= 0.876 to 2.9) for six of the seven events, tripling the number of afterglows with redshift measurements discovered by optical surveys without a
γ
-ray trigger. A likely associated LGRB (GRB 200524A, GRB 210204A, GRB 210212B, and GRB 210610B) was identified for four events (ZTF 20abbiixp/AT 2020kym, ZTF 21aagwbjr/AT 2021buv, ZTF 21aakruew/AT 2021cwd, and ZTF 21abfmpwn/AT 2021qbd) post facto, while three (ZTF 20aajnksq/AT 2020blt, ZTF 21aaeyldq/AT 2021any, and ZTF 21aayokph/AT 2021lfa) had no detected LGRB counterpart. The simplest explanation for the three “orphan” events is that they were regular LGRBs missed by high-energy satellites owing to detector sensitivity and duty cycle, although it is possible that they were intrinsically subluminous in
γ
-rays or viewed slightly off-axis. We rule out a scenario in which dirty fireballs have a similar energy per solid angle to LGRBs and are an order of magnitude more common. In addition, we set the first direct constraint on the ratio of the opening angles of the material producing
γ
-rays and the material producing early optical afterglow emission, finding that they must be comparable.
Abstract
We present and analyze a near-infrared (NIR) spectrum of the underluminous Type Ia supernova SN 2020qxp/ASASSN-20jq obtained with NIRES at the Keck Observatory, 191 days after
B
-band ...maximum. The spectrum is dominated by a number of broad emission features, including the Fe
ii
at 1.644
μ
m, which is highly asymmetric with a tilted top and a peak redshifted by ≈2000 km s
−1
. In comparison with 2D non-LTE synthetic spectra computed from 3D simulations of off-center delayed-detonation Chandrasekhar-mass (
M
ch
) white dwarf (WD) models, we find good agreement between the observed lines and the synthetic profiles, and are able to unravel the structure of the progenitor’s envelope. We find that the size and tilt of the Fe
ii
1.644
μ
m profile (in velocity space) is an effective way to determine the location of an off-center delayed-detonation transition (DDT) and the viewing angle, and it requires a WD with a high central density of ∼4 × 10
9
g cm
−3
. We also tentatively identify a stable Ni feature around 1.9
μ
m characterized by a “pot-belly” profile that is slightly offset with respect to the kinematic center. In the case of SN 2020qxp/ASASSN-20jq, we estimate that the location of the DDT is ∼0.3
M
WD
off center, which gives rise to an asymmetric distribution of the underlying ejecta. We also demonstrate that low-luminosity and high-density WD SN Ia progenitors exhibit a very strong overlap of Ca and
56
Ni in physical space. This results in the formation of a prevalent Ca
ii
0.73
μ
m emission feature that is sensitive to asymmetry effects. Our findings are discussed within the context of alternative scenarios, including off-center C/O detonations in He-triggered sub-
M
Ch
WDs and the direct collision of two WDs. Snapshot programs with Gemini/Keck/Very Large Telescope (VLT)/ELT-class instruments and our spectropolarimetry program are complementary to mid-IR spectra by the James Webb Space Telescope (JWST).
Development of the sensor head for the StarBurst multimessenger pioneer Woolf, Richard S.; Kocevski, Daniel; Grove, J. Eric ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
July 2024, 2024-07-00, Volume:
1064
Journal Article
Peer reviewed
The StarBurst Multimessenger Pioneer is a highly sensitive wide-field gamma-ray monitor designed to detect the prompt emission of short gamma-ray bursts, a key electromagnetic signature of neutron ...star mergers. StarBurst is designed to enhance the new era of multimessenger astronomy by using the advancements in gamma-ray detectors made over the past decade, namely in silicon photomultipliers (SiPMs) for light readout. With >400% the effective area of the Fermi Gamma-ray Burst Monitor and full coverage of the unocculted sky, the StarBurst observations of electromagnetic counterparts to neutron star mergers make it a key partner to the gravitational wave network in discovering these mergers at a fraction of the cost of currently operating gamma-ray missions. The StarBurst Sensor Head consists of 12 thallium-doped cesium iodide (CsI:Tl) scintillation detectors, each of which uses a custom array of low-mass, low-voltage SiPMs to cover an energy range 50 keV–2000 keV. The manuscript outlines the science of StarBurst; the predecessor technology demonstrator instrument, Glowbug; instrument design including mechanical, electrical, and data acquisition; and, the performance results from a crystal detector unit.
GRB 221009A, The BOAT Burns, Eric; Svinkin, Dmitry; Fenimore, Edward ...
arXiv (Cornell University),
03/2024
Paper, Journal Article
Open access
GRB 221009A has been referred to as the Brightest Of All Time (the 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 \(\sim99\)th percentile of the known distribution. We explore how such a burst can be powered and discuss potential implications for ultra-long 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, while it almost certainly not the BOAT over all of cosmic history, it may be the brightest gamma-ray burst since human civilization began.
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.
Dirty fireballs are a hypothesized class of relativistic massive-star explosions with an initial Lorentz factor \(\Gamma_\mathrm{init}\) below the \(\Gamma_\mathrm{init}\sim100\) required to produce ...a long-duration gamma-ray burst (LGRB), but which could still produce optical emission resembling LGRB afterglows. Here we present the results of a search for on-axis optical afterglows using the Zwicky Transient Facility (ZTF). Our search yielded seven optical transients that resemble on-axis LGRB afterglows in terms of their red colors (\(g-r>0\) mag), faint host galaxy (\(r>23\) mag), and rapid fading (\(dr/dt>1\) mag/day). Spectroscopy of the transient emission within a few days of discovery established cosmological distances (\(z=0.876\) to \(z=2.9\)) for six events, tripling the number of afterglows with redshift measurements discovered by optical surveys without a \(\gamma\)-ray trigger. Upon a retrospective search, four events (ZTF20abbiixp/AT2020kym, ZTF21aagwbjr/AT2021buv, ZTF21aakruew/AT2021cwd, ZTF21abfmpwn/AT2021qbd) turned out to have a likely associated LGRB (GRB200524A, GRB210204A, GRB210212B, GRB210610B), while three did not (ZTF20aajnksq/AT2020blt, ZTF21aaeyldq/AT2021any, ZTF21aayokph/AT2021lfa). Our search revealed no definitive new class of events: the simplest explanation for the apparently "orphan" events is that they were regular LGRBs missed by high-energy satellites due to detector sensitivity and duty cycle, although it is possible that they were intrinsically faint in \(\gamma\)-rays or viewed slightly off-axis. We rule out a scenario in which dirty fireballs have a similar energy per solid angle to LGRBs and are an order of magnitude more common. In addition, we set the first direct constraint on the ratio of the opening angles of the material producing \(\gamma\)-rays and the material producing early optical afterglow emission, finding that they must be comparable.
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.
Abstract
We present a study of the influence of magnetic field strength and morphology in Type Ia supernovae and their late-time light curves and spectra. In order to both capture self-consistent ...magnetic field topologies and evolve our models to late times, a two-stage approach is taken. We study the early deflagration phase (∼1 s) using a variety of magnetic field strengths and find that the topology of the field is set by the burning, independent of the initial strength. We study late-time (∼1000 days) light curves and spectra with a variety of magnetic field topologies and infer magnetic field strengths from observed supernovae. Lower limits are found to be 10
6
G. This is determined by the escape, or lack thereof, of positrons that are tied to the magnetic field. The first stage employs 3D MHD and a local burning approximation and uses the code Enzo. The second stage employs a hybrid approach, with 3D radiation and positron transport and spherical hydrodynamics. The second stage uses the code HYDRA. In our models, magnetic field amplification remains small during the early deflagration phase. Late-time spectra bear the imprint of both magnetic field strength and morphology. Implications for alternative explosion scenarios are discussed.
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