J/ApJ/843/143 Polarimetry & photometry of GRB with RINGO2 (Steele+, 2017)
Polarimetry and photometry of gamma-ray bursts with RINGO2.
Steele I.A., Kopac D., Arnold D.M., Smith R.J., Kobayashi S., Jermak H.E.,
Mundell C.G., Gomboc A., Guidorzi C., Melandri A., Japelj J.
<Astrophys. J., 843, 143 (2017)>
=2017ApJ...843..143S 2017ApJ...843..143S
ADC_Keywords: GRB ; Polarization ; Photometry, SDSS ; Redshifts
Keywords: gamma-ray burst: general; magnetic fields; polarization
Abstract:
We present a catalog of early-time (∼102-104s) photometry and
polarimetry of all gamma-ray burst (GRB) optical afterglows observed
with the RINGO2 imaging polarimeter on the Liverpool Telescope. Of the
19 optical afterglows observed, the following nine were bright enough
to perform photometry and attempt polarimetry: GRB100805A, GRB101112A,
GRB110205A, GRB110726A, GRB120119A, GRB120308A, GRB120311A,
GRB120326A, and GRB120327A. We present multiwavelength light curves
for these 9 GRBs, together with estimates of their optical
polarization degrees and/or limits. We carry out a thorough
investigation of detection probabilities, instrumental properties, and
systematics. Using two independent methods, we confirm previous
reports of significant polarization in GRB 110205A and 120308A, and
report the new detection of P=6-2+3% in GRB101112A. We discuss the
results for the sample in the context of the reverse- and
forward-shock afterglow scenario, and show that GRBs with detectable
optical polarization at early time have clearly identifiable
signatures of reverse-shock emission in their optical light curves.
This supports the idea that GRB ejecta contain large-scale magnetic
fields, and it highlights the importance of rapid-response
polarimetry.
Description:
Between 2010 and 2012, 19 optical afterglows were observed with the
RINGO2 polarimeter on the Liverpool Telescope (LT) at La Palma.
Table 2 shows observational properties of the complete sample.
In addition to the RINGO2 observations, optical band photometry of
each burst was carried out using the RATCam CCD imaging camera on the
same telescope, using either g'r'i' or r'i'z' filter sequences, in
intervals between and after the RINGO2 observations.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . this file
table2.dat 76 28 The complete sample of 19 GRB afterglows observed
with RINGO2
table3.dat 82 17 Polarization results
table5.dat 55 397 RINGO2 sample complete photometry
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See also:
J/ApJ/743/154 : Multi-band photom. of GRB 110205A+110213A (Cucchiara+, 2011)
J/ApJ/746/156 : Radio afterglow observations of GRBs (Chandra+, 2012)
J/ApJ/763/15 : Fermi GRB analysis. III. T90 distributions (Qin+, 2013)
J/ApJ/772/73 : GRB with early-time optical emission (Kopac+, 2013)
J/ApJS/209/20 : Swift GRB catalog with X-ray data (Grupe+, 2013)
J/MNRAS/428/729 : GRB Swift X-ray light curves analysis (Margutti+, 2013)
J/A+A/565/A72 : Optical & X-ray light curves of BAT6 sample (Melandri+, 2014)
J/ApJ/787/66 : Burst duration measurements for a GRB sample (Zhang+, 2014)
J/ApJ/787/90 : Gamma-ray bursts minimum timescales (Golkhou+, 2014)
J/A+A/581/A125 : UV/Optical/NIR spectroscopy GRB hosts (Kruehler+, 2015)
J/A+A/584/A48 : New redshifts of 357 GBBs (Horvath+, 2015)
J/ApJ/800/16 : Swift-XRT long GRB durations (Boer+, 2015)
J/ApJ/811/93 : Fermi/GBM GRB minimum timescales (Golkhou+, 2015)
J/ApJ/814/1 : GRB 120326A, 100418A+100901A observations (Laskar+, 2015)
J/ApJ/826/45 : GRB X-ray afterglows light curves analysis (Racusin+, 2016)
J/ApJ/828/36 : GRB light-curve decay indices with Swift (Del Vecchio+, 2016)
J/ApJS/224/20 : 10yr of Swift/XRT obs. of GRBs (Yi+, 2016)
J/ApJS/227/7 : Long + short GRBs with host galaxies data (Li+, 2016)
J/A+A/589/A97 : GRBs Ep and Fourier PDS slope correlation (Dichiara+, 2016)
J/A+A/589/A98 : Swift GRBs individual power density spectra (Guidorzi+, 2016)
J/MNRAS/464/4545 : GRBs with Swift data (2004-2015) (Buchner+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- GRB GRB name (1)
9- 12 I4 s t-T0l Lower range of t-T0 (2)
13 A1 --- --- [-]
14- 17 I4 s t-T0u Upper range of t-T0 (2)
19 A1 --- l_r'mag [≳] Upper or uncertainty flag on r'mag (3)
21- 25 F5.2 --- r'mag [15.7/22.5]? r' band magnitude at mid-time
of the RINGO2 epoch
27- 30 F4.2 --- e_r'mag [0.03/0.7]? r'mag uncertainty (4)
32- 36 I5 s tmag [215/42469]? Nearest time (3)
38- 56 A19 --- Auth GCN Author' reference (3)
58- 76 A19 --- Ref GCN bibcode' reference (3)
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Note (1): All bursts were initially detected by Swift, except for GRB101112A,
which was detected by INTEGRAL.
Note (2): Time of RINGO2 observations with respect to the gamma-ray trigger.
Note (3): When no r' magnitude with error is reported, the source was too faint
to be observed with RINGO2 and a limit or measurement from the GCN
report nearest in time is given.
Note (4): Photometric errors quoted are the statistical error on the
observation. In particular, those calibrated with respect to USNO-B1
catalogs (GRB 110726A, GRB 120326A) show larger systematic errors
(typically 0.3 mag).
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- GRB GRB name
9- 12 I4 s t-T0l Lower range of t-T0 (RINGO2 obs. interval)
13 A1 --- --- [-]
14- 17 I4 s t-T0u Upper range of t-T0 (RINGO2 obs. interval)
19 A1 --- l_Pol Upper limit flag on Pol
20- 21 I2 % Pol [4/28] Degree of polarization
23 I1 % e_Pol [2/9]? Negative uncertainty on Pol
25- 26 I2 % E_Pol [3/13]? Positive uncertainty on Pol
28- 30 I3 deg EVPA [34/126]? Measured polarization sky angle
(east of north)
32- 33 I2 deg e_EVPA [4/26]? EVPA uncertainty
35 A1 --- l_Rank Lower limit flag on Rank
36- 40 F5.3 --- Rank [0.008/1] Rank of the polarization measurement
in permutation analysis
42 A1 --- l_tpk Upper limit flag on tpk
43- 48 F6.1 s tpk [140/1664] Optical afterglow peak time
50- 53 F4.1 s e_tpk [6/16]? tpk uncertainty
55- 59 F5.1 s T90 [3.5/249] Gamma-ray emission duration
61- 64 F4.2 mag Av [0/0.92] Galactic extinction in V band
66- 67 A2 --- l_z [≲ ] Uncertainty flag on z
68- 72 F5.3 --- z [1.3/3.5]? Redshift
73 A1 --- f_z a: GRB110726A has 1.04<z<2.7
74- 77 F4.2 --- e_z ? Negative uncertainty on z
79- 82 F4.2 --- E_z ? Positive uncertainty on z
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- GRB Gamma-ray burst identifier
9- 15 F7.2 min tStart [1.9/1351]?=0 Start time
17- 22 F6.1 s Exp [7/7200]?=0 Exposure time
24- 29 A6 --- Inst Instrument used in the observation (PROMPT,
RATCam, RINGO or UVOT) (1)
31- 32 A2 --- Filt Filter used in the observation (I, R, g'i'r'z',
or ubv)
34- 38 F5.2 mag mag [14.3/23.1]?=0 Apparent magnitude in Filter;
corrected for the Galactic extinction
40- 43 F4.2 mag e_mag [0.01/0.6]?=0 Uncertainty in mag
45- 49 F5.3 mJy Flux [0.003/7.1]?=0 Flux density
51- 55 F5.3 mJy e_Flux [0.001/0.6]?=0 Uncertainty in Flux
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Note (1): For GRB110205A, additional SWIFT UVOT u, b and v magnitudes were all
obtained from Cucchiara+ (2011, J/ApJ/743/154).
For GRB120119A, additional PROMPT data in R and I filters from Morgan+
(2014MNRAS.440.1810M 2014MNRAS.440.1810M) was used.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Mar-2018