J/ApJ/814/1 GRB 120326A, 100418A & 100901A multi-wavelength obs. (Laskar+, 2015)
Energy injection in gamma-ray burst afterglows.
Laskar T., Berger E., Margutti R., Perley D., Zauderer B.A., Sari R.,
Fong W.-F.
<Astrophys. J., 814, 1 (2015)>
=2015ApJ...814....1L 2015ApJ...814....1L (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays ; X-ray sources ; Ultraviolet ; Energy distributions ;
Millimetric/submm sources
Keywords: gamma-ray burst: general;
gamma-ray burst: individual: (GRB 100418A, GRB 100901A, GRB 120326A,
GRB 120404A)
Abstract:
We present multi-wavelength observations and modeling of gamma-ray
bursts (GRBs) that exhibit a simultaneous re-brightening in their
X-ray and optical light curves, and are also detected at radio
wavelengths. We show that the re-brightening episodes can be modeled
by injection of energy into the blastwave and that in all cases the
energy injection rate falls within the theoretical bounds expected for
a distribution of energy with ejecta Lorentz factor. Our measured
values of the circumburst density, jet opening angle, and
beaming-corrected kinetic energy are consistent with the distribution
of these parameters for long-duration GRBs at both z∼1 and z≳6,
suggesting that the jet launching mechanism and environment of these
events are similar to that of GRBs that do not have bumps in their
light curves. However, events exhibiting re-brightening episodes have
lower radiative efficiencies than average, suggesting that a majority
of the kinetic energy of the outflow is carried by slow-moving ejecta,
which is further supported by steep measured distributions of the
ejecta energy as a function of Lorentz factor. We do not find evidence
for reverse shocks over the energy injection period, implying that the
onset of energy injection is a gentle process. We further show that
GRBs exhibiting simultaneous X-ray and optical re-brightenings are
likely the tail of a distribution of events with varying rates of
energy injection, forming the most extreme events in their class.
Future X-ray observations of GRB afterglows with Swift and its
successors will thus likely discover several more such events, while
radio follow-up and multi-wavelength modeling of similar events will
unveil the role of energy injection in GRB afterglows.
Description:
GRB 120326A was discovered by the Swift Burst Alert Telescope (BAT)
on 2012 March 26 at 01:20:29 UT. Spectroscopic observations at the
10.4m Gran Telescope Canarias provided a redshift of z=1.798 (Tello
et al. 2012GCN..13118...1T). The burst also triggered the Fermi
Gamma-ray Burst Monitor (GBM) at 01:20:31.51 UT.
The Swift XRT began observing the field at 69s after the BAT trigger.
The source was localized to RAJ2000=18:15:37.06, DEJ2000=+69:15:35.4,
with an uncertainty radius of 1.4 arcsec (90% containment).
The Swift UV/Optical Telescope (UVOT) observed GRB 120326A using 6
filters spanning the central wavelength range λc=1928Å
(W2) to λc=5468Å (v) beginning 67s after the burst. See
table 1.
We observed GRB 120326A with the Wide-field Infrared Camera (J and
Ks-band) on the Palomar 200-inch telescope beginning on 2012 March
30.48 UT. We also carried out a series of imaging observations of
GRB120326A with the robotic Palomar 60-inch telescope on the nights of
2012 March 31, April 02, April 03 (r' and i'), April 04, April 08, and
April 16 (r' only). Finally, we collected other optical and NIR
observations of GRB120326A reported through the Gamma-ray Burst
Coordinates Network (GCN) Circulars and converted all photometry to
flux densities. See table 2.
We observed GRB 120326A with the Combined Array for Research in
Millimeter Astronomy (CARMA) beginning on 2012 March 30.56 UT (4.52d
after the burst) at a mean frequency of 93GHz. The SMA observed GRB
120326A at a mean frequency of 222GHz between 2012 March 26.43 UT
(0.37d after the burst) and 2012 April 11.64 UT (16.6d after the
burst). These observations have been reported in Urata et al.
(2014ApJ...789..146U 2014ApJ...789..146U).
We observed the afterglow at C (4-7GHz), K (18-25GHz), and Ka
(30-38GHz) bands using the Karl G. Jansky VLA starting 5.45d after the
burst. See table 3.
GRB 100418A was detected and localized by the Swift BAT on 2010 April
18 at 21:10:08 UT. The afterglow was detected in the X-ray and optical
bands by XRT, UVOT, and various ground-based observatories, as well as
in the radio by WSRT, VLA, the Australia Telescope Compact Array
(ATCA), and the Very Long Baseline Array (VLBA). Spectroscopic
observations with the ESO Very Large Telescope (VLT) yielded a
redshift of z=0.6235. See table 6 and section 6.1.
GRB 100901A was detected and localized by the Swift BAT on 2010
September 01 at 13:34:10 UT. The afterglow was detected in the X-rays
and optical bands by XRT, UVOT, and by multiple ground-based
observatories, as well as in the radio by the WSRT and the VLA.
Spectroscopic observations with Magellan yielded a redshift of
z=1.408. See tables 7 and 8 and section 6.2.
Objects:
-----------------------------------------------------------------------
RA (ICRS) DE Designation(s) Redshift
-----------------------------------------------------------------------
18 15 37.06 +69 15 35.4 GRB 120326A = Fermi bn120326056 (z=1.798)
17 05 26.96 +11 27 41.9 GRB 100418A = GRB 100418A (z=0.6235)
01 49 03.56 +22 45 30.6 GRB 100901A = GRB 100901A (z=1.408)
-----------------------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 40 52 Swift/UVOT Observations of GRB 120326A
table2.dat 112 138 Optical Observations of GRB 120326A
table3.dat 57 34 Millimeter and Radio Observations of GRB 120326A
table6.dat 40 64 Swift/UVOT Observations of GRB 100418A
table7.dat 40 125 Swift/UVOT Observations of GRB 100901A
table8.dat 112 263 Optical Observations of GRB 100901A
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See also:
VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)
J/A+A/581/A125 : UV/Optical/NIR spectroscopy GRB hosts (Kruehler+, 2015)
J/A+A/557/A12 : Optical light curves of γ-ray bursts (Zaninoni+, 2013)
J/ApJS/209/20 : Swift GRB catalog with X-ray data (Grupe+, 2013)
J/ApJ/774/157 : Swift GRBs with X-ray afterglows and z<9.5 (Dainotti+, 2013)
J/MNRAS/428/729 : GRB Swift X-ray light curves analysis (Margutti+, 2013)
J/ApJS/199/18 : The Fermi GBM catalog (Paciesas+, 2012)
J/ApJ/746/170 : Follow-up resources for high-redshift GRBs (Morgan+, 2012)
J/MNRAS/421/1874 : GRB 100901A and GRB 100906A light curves (Gorbovskoy+, 2012)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/AJ/130/873 : BQS objects data in the SDSS DR3 area (Jester+, 2005)
http://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html : Fermi GBM bursts
http://www.swift.ac.uk/xrt_positions/ : Swift-XRT GRB positions
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.5 d t [0.001/19.5] Time since discovery; t-t0
10- 14 A5 --- Filt Filter used in the observation (White, u, b,
v, uvm2, uvw1 or uvw2)
16- 23 E8.2 Hz Freq [5.5e+14/1.5e+15] Frequency of Filter peak
25- 31 F7.3 uJy Flux [0.2/150] Flux density (1)
33- 38 F6.3 uJy e_Flux [0.5/15] Uncertainty in Flux
40 I1 --- Det? [0/1] Detection flag; 1 = Detection
--------------------------------------------------------------------------------
Note (1): In cases of non-detections, we report the formal flux density
measurement from aperture photometry.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[28].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.6 d t [0.0002/21.4] Time since discovery; t-t0
11- 22 A12 --- Obs Observatory identifier
24- 34 A11 --- T/I Telescope/Instrument description
36- 37 A2 --- Filt Filter used in the observation (CR, JHK, RI,
RcIc, g'r'i'z', bv or Y')
39- 46 E8.1 Hz Freq [1.3e+14/7e+14] Effective frequency
48- 54 F7.2 uJy Flux [1.6/4040] Flux density (1)
56- 64 F9.4 uJy e_Flux [0.09/1350] Uncertainty in Flux
66 I1 --- Det? [0/1] Detection flag; 1 = Detection
68- 92 A25 --- Aut First author's name(s) of the reference (2)
94-112 A19 --- BibCode Bibcode of the reference (2)
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Note (1): In cases of non-detections, we report the 3σ upper limit
on the flux density.
Note (2): We note that the photometry reported in Table 1 of
Urata et al. (2014ApJ...789..146U 2014ApJ...789..146U) yields an unphysical spectral index
of Β~-4.5 for GRB 120326A. We assume that these numbers have been
scaled by the same factors as reported in Figure 4 of their paper, and
divide the gr'Rizy light curves by a factor of 0.5, 1, 1, 2, 4, and 6,
respectively. We further assume that the data have not been corrected
for galactic extinction.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 A14 "Y/M/D" Date UT date of the observation
16- 22 F7.3 d t [0.5/122.1] Time since discovery; t-t0
24- 28 A5 --- Obs Observatory identifier (CARMA, SMA or VLA/B,
VLA/C) (1)
30- 34 F5.1 GHz Freq [5/222] Frequency of the observation
36- 41 F6.2 min Int [4.5/386] Integration time
43 A1 --- l_Flux Limit flag on Flux
45- 49 F5.3 mJy Flux [0.05/3.4] Flux density
51- 55 F5.3 mJy e_Flux [0.01/0.9] The 1σ statistical
uncertainty in Flux
57 I1 --- Det? [0/1] Detection flag; 1 = Detection
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Note (1): The letter following "VLA" indicates the array configuration. The
PI of the SMA data set is Y. Urata.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table[67].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.5 d t [0.001/34.4] Time since discovery; t-t0
10- 14 A5 --- Filt Filter used in the observation White, u, b,
v, uvm2, uvw1 or uvw2)
16- 23 E8.2 Hz Freq [5.5e+14/1.5e+15] Frequency of Filter peak
25- 31 F7.3 uJy Flux [1.3/291] Flux density (1)
33- 38 F6.3 uJy e_Flux [0.3/76] Uncertainty in Flux
40 I1 --- Det? [0/1] Detection flag; 1 = Detection
--------------------------------------------------------------------------------
Note (1): In cases of non-detections, we report the formal flux density
measurement from aperture photometry.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Feb-2016