J/ApJ/946/L23 Multiwavelength follow-up obs. of GRB 221009A (Laskar+, 2023)
The radio to GeV afterglow of GRB 221009A.
Laskar T., Alexander K.D., Margutti R., Eftekhari T., Chornock R.,
Berger E., Cendes Y., Duerr A., Perley D.A., Ravasio M.E., Yamazaki R.,
Ayache E.H., Barclay T., Duran R.B., Bhandari S., Brethauer D.,
Christy C.T., Coppejans D.L., Duffell P., Fong W.-F., Gomboc A.,
Guidorzi C., Kennea J.A., Kobayashi S., Levan A., Lobanov A.P.,
Metzger B.D., Ros E., Schroeder G., Williams P.K.G.
<Astrophys. J., 946, L23 (2023)>
=2023ApJ...946L..23L 2023ApJ...946L..23L
ADC_Keywords: GRB; Radio sources; Photometry, millimetric/submm;
Photometry, ugriz; X-ray sources
Keywords: High energy astrophysics ; Gamma-ray bursts
Abstract:
GRB 221009A (z=0.151) is one of the closest known long γ-ray
bursts (GRBs). Its extreme brightness across all electromagnetic
wavelengths provides an unprecedented opportunity to study a member of
this still-mysterious class of transients in exquisite detail. We
present multiwavelength observations of this extraordinary event,
spanning 15 orders of magnitude in photon energy from radio to
γ-rays. We find that the data can be partially explained by a
forward shock (FS) from a highly collimated relativistic jet
interacting with a low-density, wind-like medium. Under this model,
the jet's beaming-corrected kinetic energy (EK∼4x1050erg) is
typical for the GRB population. The radio and millimeter data provide
strong limiting constraints on the FS model, but require the presence
of an additional emission component. From equipartition arguments, we
find that the radio emission is likely produced by a small amount of
mass (≲6x10-7M☉) moving relativistically (Γ≳9) with a
large kinetic energy (≳1049erg). However, the temporal evolution of
this component does not follow prescriptions for synchrotron radiation
from a single power-law distribution of electrons (e.g., in a reverse
shock or two-component jet), or a thermal- electron population,
perhaps suggesting that one of the standard assumptions of afterglow
theory is violated. GRB 221009A will likely remain detectable with
radio telescopes for years to come, providing a valuable opportunity
to track the full lifecycle of a powerful relativistic jet.
Description:
We observed the afterglow using the upgraded Giant Metrewave Radio
Telescope (GMRT) through program 43_039 (PI: Laskar) starting 18.0d,
21.9d, and 21.8d after the burst in bands 3 (400MHz), 4 (750MHz), and
5 (1260MHz), respectively. The observations utilized 400MHz bandwidth.
See Section 2.1.1.
We also observed the afterglow with the MeerKAT radio telescope
beginning at ∼1.3 days after the burst in the L band (1.3GHz) via
program SCI-20220822-TL-01 (PI: Laskar). See Section 2.1.2.
We obtained seven epochs of multifrequency observations of GRB 221009A
beginning ∼3.5d after the burst with the Karl G. Jansky Very Large
Array (VLA) through program 22B_062 (PI: Laskar). See Section 2.1.3.
We also obtained four epochs of observations of GRB 221009A with the
Very Long Baseline Array (VLBA) and the 100m radio telescope
Effelsberg at 8.3GHz, beginning ∼12.4 days after the burst, under
project VLBA/22B-305 (Legacy Code BL073; PI: Laskar). See Section 2.1.4.
We obtained four epochs of observations of the afterglow with the
Australia Telescope Compact Array (ATCA) beginning ∼5.8 days after the
burst by triggering our program C3289 (PI: Laskar) using the CABB
correlator tuned to 15mm (with 2GHz basebands tuned to 16.7 and
21.2GHz) and 7mm (33 and 35GHz, and also 45 and 47GHz). See Section 2.1.5.
We obtained seven epochs of ALMA Band 3 (3mm) observations of GRB221009A
beginning ∼2.4 days after the burst through program 2022.1.01433.T
(PI: Laskar). The observations utilized two 4GHz wide basebands
centered at 91.5 and 103.5GHz, respectively. See Section 2.1.6.
We obtained two epochs of Northern Extended Millimeter Array (NOEMA)
97.5GHz observations of GRB 221009A at 39.2 and 54.2 days after the
burst through program S22BE (PI: Laskar). The observations utilized
two 7.7GHz wide basebands centered at 89.8 and 105.2GHz, respectively.
See Section 2.1.7.
We observed the afterglow with the Submillimeter Array (SMA) at a
combination of 1.3mm (∼230GHz) and 1.1mm (290GHz) for seven epochs.
See Section 2.1.8.
We observed GRB 221009A in griz filters with IO:O on the Liverpool
Telescope (LT) at multiple epochs beginning on 2022 October 9. We
downloaded pipeline-reduced images from the LT archive.
See Section 2.2.
We performed photometry in a 5" aperture on all Swift/Ultra-violet
Optical Telescope (UVOT) images up to and including segment
01126853067 (taken on 2022 December 16) obtained from the Swift
repository. See Section 2.3.
In X-rays, the Nuclear Spectroscopic Telescope Array (NuSTAR; 3-79keV)
acquired a first set of four observations between 1.96 and 23.73 days
(PIs: Margutti & Racusin) with exposure times of ∼20ks, followed by
one deeper exposure at 31.91 days (exposure time of 40ks; PI: Troja).
See Section 2.4.1.
The Swift X-ray Telescope (XRT) began observing GRB 221009A ∼3.4ks
after the Swift/BAT trigger and ∼6.6ks after the Fermi/GBM trigger.
We extracted XRT photon counting (PC)-mode spectra at the times
corresponding to the NuSTAR epochs. See Section 2.4.2.
Finally, the Large Area Telescope (LAT) instrument on board the Fermi
satellite is sensitive to γ-ray photons in the energy band from
30MeV to 300GeV. We extracted and analyzed the Fermi/LAT data of
GRB221009A within a temporal window from 3.5 to 100ks (0.04-1.16d)
after the GBM trigger time. See Section 2.5.
Objects:
------------------------------------------------------------
RA (ICRS) DE Designation(s)
------------------------------------------------------------
19 13 03.84 +19 46 22.6 GRB 221009A = Fermi bn221009553
------------------------------------------------------------
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 57 146 Radio observations of GRB 221009A
table2.dat 31 70 Liverpool Telescope observations of GRB 221009A
table3.dat 30 18 Swift/UVOT observations of GRB 221009A
table4.dat 74 5 Log of NuSTAR observations
table5.dat 72 8 Fermi/LAT Observations
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See also:
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJ/781/37 : Multi-band photometry of GRB 130427A (Perley+, 2014)
J/ApJ/814/1 : GRB 120326A, 100418A & 100901A multi-wave. obs. (Laskar+, 2015)
J/ApJ/833/88 : GRB 160509A VLA monitoring campaign results (Laskar+, 2016)
J/ApJ/862/94 : Multiwavelength obs. of GRB 161219B (Laskar+, 2018)
J/ApJ/884/121 : Radio to UV observations of GRB 181201A (Laskar+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.4 d Time [1.14/99.1] Mid-time since Fermi/GBM trigger (1)
9- 18 E10.3 Hz Freq [4e+08/3.5e+11] Center frequency
20- 26 F7.1 uJy FluxD [10/15000] Flux density
28- 33 F6.1 uJy e_FluxD [15/1300] Flux density uncertainty
35- 35 I1 --- Det [0/1] Detection flag: 1 for detection,
0 for 3σ upper limit
37- 43 A7 --- Obs Observatory (2)
45- 49 A5 --- Band Radio band
51- 55 I5 --- Ref [0/32736]? References (3)
57- 57 A1 --- Flag Observation flag(s) (4)
--------------------------------------------------------------------------------
Note (1): Mid-time since Fermi/GBM trigger at 2022-10-09 13:16:59.000 UT.
Note (2): Observatory as follows:
VLA = the Karl G. Jansky Very Large Array (86 occurrences)
ATCA = the Australia Telescope Compact Array (14 occurrences)
SMA = the Submillimeter Array (11 occurrences)
MeerKAT = the MeerKAT radio telescope (10 occurrences)
GMRT = the upgraded Giant Metrewave Radio Telescope (10 occurrences)
ALMA = the Atacama Large Millimeter/submillimeter Array (7 occurrences)
VLBA = the Very Long Baseline Array (4 occurrences)
NOEMA = the Northern Extended Millimeter Array (3 occurrences)
ASKAP = 1 occurrence
Note (3): References as follows:
0 = this work;
32676 = GCN 32676; de Ugarte Postigo et al. 2022/10/11 09:09:27 GMT,
32736 = GCN 32736; Leung, Lenc, Murphy, 2022/10/13 10:48:46 GMT
Note (4): Observation flags as follows:
a = The noise in the image of L-band data taken on 2022 Oct 15
was much higher than in the other epochs due to significant
RFI contamination;
b = The sixth ALMA epoch used J1550+0527 as flux density
calibrator; this execution was affected by a correlator issue
and was re-observed, the second time using J2232+1143, which
is the value reported here;
c = The cleaning process reveals residuals characteristic of
phase decorrelation and the resulting ATCA SEDs are extremely
steep and are inconsistent with an extrapolation to nearly
contemporaneous ALMA observations. Whereas phase-only
self-calibration recovers some flux, the signal-to-noise in
the data is too low for adequate self-calibration. We list
the ATCA measurements for completeness, but we do not use
these in the modeling in this work, and we caution against
the use of these data in other works without more careful
attention to the calibration;
d = For the second VLA epoch taken on 2022 Oct 15, the flux
calibrator scans were defective. We calibrated this
observation using flux calibrator data at the same
frequencies taken from the first epoch instead, and achieved
excellent agreement for the derived flux density of the gain
calibrator.
e = No uncertainty was reported for this measurement and an SNR of 15
was assumed.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.5 d Time [0.3/38.3] Mid-time since Fermi/GBM trigger (1)
10- 10 A1 --- Filt [griz] Filter
12- 16 F5.2 mag omag [15.29/24.1] Observed AB magnitude in Filter (2)
18- 21 F4.2 mag e_omag [0.01/0.8] Uncertainty in omag (2)
23- 26 I4 s Tint [30/1800] Integration time
28- 31 F4.2 arcsec Seeing [0.75/2.7] Seeing
--------------------------------------------------------------------------------
Note (1): Mid-time since Fermi/GBM trigger at 2022-10-09 13:16:59.000 UT.
Note (2): The data have not been corrected for extinction in the
Milky Way or GRB host galaxy, or for the contribution of host galaxy light.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.1 s Start [337.2/97761.4] Start Time (1)
9- 15 F7.1 s Stop [586.9/98526.1] Stop Time (1)
17- 19 A3 --- Band Swift/UVOT Band
21- 25 F5.2 mag omag [15.5/20.9] Observed magnitude in Band (2)
27- 30 F4.2 mag e_omag [0.07/0.4] Uncertainty in omag (2)
--------------------------------------------------------------------------------
Note (1): Times in seconds since Swift/BAT trigger
-- Add 3199s to convert to time relative to Fermi/GBM trigger at
2022-10-09 13:16:59.000 UT
Note (2): Magnitudes are in the native Swift/UVOT system and have not
been corrected for extinction in the Milky Way or GRB host galaxy.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 "datime" Start Start Date Time, ISO 8601
21- 39 A19 "datime" Stop Stop Date Time, ISO 8601
41- 52 F12.6 d MJD [59863.5/59893.5] Centroid Modified Julian Date,
JD-2400000.5)
54- 58 F5.2 d Time [1.96/31.91] Time (1)
60- 64 F5.2 ks NetExp-A [20.44/40.78] Net Exposure, NuSTAR module A
66- 70 F5.2 ks NetExp-B [20.26/40.38] Net Exposure, NuSTAR module B
72- 74 F3.1 arcmin Size [1/1.5] Source region size
--------------------------------------------------------------------------------
Note (1): Time in days since Fermi/GBM trigger at 2022-10-09 13:16:59.000 UT.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 F7.1 s Start [3000/67731.6] Start Time (1)
9- 16 F8.1 s Stop [4429.2/100000] Stop Time (1)
18- 18 A1 --- l_EFlux Limit flag on EFlux
20- 27 E8.2 mW/m2 EFlux [4.3e-10/2.7e-08] Energy flux, erg/s/cm2
29- 36 E8.2 mW/m2 e_EFlux [1.8e-10/1.5e-08]? Uncertainty in EFlux
38- 38 A1 --- l_PFlux Limit flag on PFlux
40- 47 E8.2 ph/s/cm2 PFlux [5.79e-07/3.1e-05] Photon flux, photons/s/cm2
49- 56 E8.2 ph/s/cm2 e_PFlux [5e-07/1.1e-05]? Uncertainty in PFlux
58- 61 F4.2 --- Gamma [2/2.9] Photon Index, FE∝E-Γ
63- 67 F5.3 --- e_Gamma [0.14/0.5]? Uncertainty in Gamma
69- 72 I4 --- Tstat [5/177] Test statistic
--------------------------------------------------------------------------------
Note (1): Time in seconds since Fermi/GBM trigger at 2022-10-09 13:16:59.000 UT.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Feb-2025