- GCN/BACODINE POSITION NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:53:05 UT
NOTICE_TYPE: Swift-BAT GRB Position
TRIGGER_NUM: 153514, Seg_Num: 0
GRB_RA: 13.670d {+00h 54m 41s} (J2000),
13.745d {+00h 54m 59s} (current),
13.014d {+00h 52m 03s} (1950)
GRB_DEC: +14.138d {+14d 08' 17"} (J2000),
+14.169d {+14d 10' 08"} (current),
+13.867d {+13d 52' 02"} (1950)
GRB_ERROR: 4.00 [arcmin radius, statistical only]
GRB_INTEN: 0 [cnts] Image_Peak=2820 [image_cnts]
TRIGGER_DUR: 64.000 [sec]
TRIGGER_INDEX: 20000 E_range: 15-50 keV
BKG_INTEN: 0 [cnts]
BKG_TIME: 0.00 SOD {00:00:00.00} UT
BKG_DUR: 0 [sec]
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6704.28 SOD {01:51:44.28} UT
GRB_PHI: 13.39 [deg]
GRB_THETA: 35.07 [deg]
SOLN_STATUS: 0x13
RATE_SIGNIF: 0.00 [sigma]
IMAGE_SIGNIF: 13.26 [sigma]
MERIT_PARAMS: +1 +0 +0 +6 +1 +2 +0 +0 +79 +1
SUN_POSTN: 163.07d {+10h 52m 16s} +7.20d {+07d 11' 44"}
SUN_DIST: 142.81 [deg]
MOON_POSTN: 167.25d {+11h 09m 00s} +8.25d {+08d 15' 03"}
MOON_DIST: 145.45 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.12,-48.73 [deg] galactic lon,lat of the burst (or transient)
ECL_COORDS: 18.07, 7.64 [deg] ecliptic lon,lat of the burst (or transient)
COMMENTS: SWIFT-BAT GRB Coordinates.
COMMENTS: This is an image trigger. (The RATE_SIGNIF & BKG_{INTEN, TIME, DUR} are undefined.)
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
- red DSS finding chart
ps-file
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:55:56 UT
NOTICE_TYPE: Swift-BAT GRB Lightcurve
TRIGGER_NUM: 153514, Seg_Num: 0
GRB_RA: 13.670d {+00h 54m 41s} (J2000),
13.745d {+00h 54m 59s} (current),
13.014d {+00h 52m 03s} (1950)
GRB_DEC: +14.138d {+14d 08' 17"} (J2000),
+14.169d {+14d 10' 08"} (current),
+13.867d {+13d 52' 02"} (1950)
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6704.28 SOD {01:51:44.28} UT
TRIGGER_INDEX: 20000
GRB_PHI: 13.39 [deg]
GRB_THETA: 35.07 [deg]
DELTA_TIME: 0.00 [sec]
TRIGGER_DUR: 64.000 [sec]
LC_URL: sw00153514000msb.lc
SUN_POSTN: 163.07d {+10h 52m 16s} +7.20d {+07d 11' 44"}
SUN_DIST: 142.81 [deg]
MOON_POSTN: 167.25d {+11h 09m 00s} +8.25d {+08d 15' 03"}
MOON_DIST: 145.45 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.12,-48.73 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 18.07, 7.64 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-BAT GRB Lightcurve.
COMMENTS:
COMMENTS: The next comments were copied from the BAT_POS Notice:
COMMENTS: This is an image trigger.
COMMENTS: A point_source was found.
COMMENTS: This does not match any source in the on-board catalog.
COMMENTS: This does not match any source in the ground catalog.
COMMENTS: This is a GRB.
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:56:30 UT
NOTICE_TYPE: Swift-UVOT Source List
TRIGGER_NUM: 153514, Seg_Num: 0
POINT_RA: 13.662d {+00h 54m 39s} (J2000)
POINT_DEC: +14.090d {+14d 05' 24"} (J2000)
POINT_ROLL: 56.837d
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6868.26 SOD {01:54:28.26} UT
FILTER: 3, V
BKG_MEAN: 1055216280
N_STARS: 1687
X_OFFSET: 1913 [pixels]
Y_OFFSET: 19 [pixels]
X_MAX: 728 [pixels]
Y_MAX: 954 [pixels]
DET_THRESH: 6
PHOTO_THRESH: 3
SL_URL: sw00153514000msufc.fits
SUN_POSTN: 163.07d {+10h 52m 17s} +7.19d {+07d 11' 41"}
SUN_DIST: 142.85 [deg]
MOON_POSTN: 167.27d {+11h 09m 05s} +8.24d {+08d 14' 25"}
MOON_DIST: 145.51 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.11,-48.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 18.04, 7.60 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Source List.
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:57:20 UT
NOTICE_TYPE: Swift-UVOT Processed Source List
TRIGGER_NUM: 153514, Seg_Num: 0
POINT_RA: 13.662d {+00h 54m 39s} (J2000)
POINT_DEC: +14.090d {+14d 05' 24"} (J2000)
POINT_ROLL: 56.837d
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6868.26 SOD {01:54:28.26} UT
FILTER: 3, V
BKG_MEAN: 1055216280
N_STARS: 1687
X_OFFSET: 1913 [pixels]
Y_OFFSET: 19 [pixels]
X_MAX: 728 [pixels]
Y_MAX: 954 [pixels]
DET_THRESH: 6
PHOTO_THRESH: 3
SL_URL: sw00153514000msufc.fits
SUN_POSTN: 163.07d {+10h 52m 17s} +7.19d {+07d 11' 41"}
SUN_DIST: 142.85 [deg]
MOON_POSTN: 167.27d {+11h 09m 05s} +8.24d {+08d 14' 25"}
MOON_DIST: 145.51 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.11,-48.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 18.04, 7.60 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Processed Source List.
COMMENTS: If you have elected to receive attachments:
COMMENTS: The uvot_catalog_srclist.fits file does not exist; skipping the attachment.
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:57:35 UT
NOTICE_TYPE: Swift-UVOT Image
TRIGGER_NUM: 153514, Seg_Num: 0
POINT_RA: 13.662d {+00h 54m 39s} (J2000)
POINT_DEC: +14.090d {+14d 05' 24"} (J2000)
ROLL: 56.837d
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6868.26 SOD {01:54:28.26} UT
FILTER: 3, V
EXPOSURE_ID: 2250
X_OFFSET: 2072 [pixels]
Y_OFFSET: 1274 [pixels]
WIDTH: 0 [pixels]
HEIGHT: 0 [pixels]
X_GRB_POS: 0
Y_GRB_POS: 0
BINNING_INDEX: 0
IM_URL: sw00153514000msuni.fits
SUN_POSTN: 163.07d {+10h 52m 17s} +7.19d {+07d 11' 41"}
SUN_DIST: 142.85 [deg]
MOON_POSTN: 167.27d {+11h 09m 05s} +8.24d {+08d 14' 25"}
MOON_DIST: 145.51 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.11,-48.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 18.04, 7.60 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Image.
COMMENTS: The GRB Position came from the Window Position in the Mode
+Command.
COMMENTS: The image has 1x1 binning (ie no compression).
- GCN/SWIFT NOTICE
TITLE: GCN/SWIFT NOTICE
NOTICE_DATE: Sun 04 Sep 05 01:58:24 UT
NOTICE_TYPE: Swift-UVOT Processed Image
TRIGGER_NUM: 153514, Seg_Num: 0
POINT_RA: 13.662d {+00h 54m 39s} (J2000)
POINT_DEC: +14.090d {+14d 05' 24"} (J2000)
ROLL: 56.837d
GRB_DATE: 13617 TJD; 247 DOY; 05/09/04
GRB_TIME: 6868.26 SOD {01:54:28.26} UT
FILTER: 3, V
EXPOSURE_ID: 2250
X_OFFSET: 2072 [pixels]
Y_OFFSET: 1274 [pixels]
WIDTH: 0 [pixels]
HEIGHT: 0 [pixels]
X_GRB_POS: 0
Y_GRB_POS: 0
BINNING_INDEX: 0
IM_URL: sw00153514000msuni.fits
SUN_POSTN: 163.07d {+10h 52m 17s} +7.19d {+07d 11' 41"}
SUN_DIST: 142.85 [deg]
MOON_POSTN: 167.27d {+11h 09m 05s} +8.24d {+08d 14' 25"}
MOON_DIST: 145.51 [deg]
MOON_ILLUM: 0 [%]
GAL_COORDS: 124.11,-48.77 [deg] galactic lon,lat of the pointing direction
ECL_COORDS: 18.04, 7.60 [deg] ecliptic lon,lat of the pointing direction
COMMENTS: SWIFT-UVOT Processed Image.
COMMENTS: If you have elected to receive attachments:
COMMENTS: The uvot_catalog_image.fits file does not exist; skipping the
attachment.
- GCN notice #3910
J. Cummings (GSFC/NRC), L. Angelini (GSFC), S. Barthelmy (GSFC), A. Cucchiara (PSU),
N. Gehrels (GSFC), C. Gronwall (PSU), S.T. Holland (GSFC), V. Mangano (INAF-IASF),
F. Marshall (GSFC), C. Pagani (PSU), D. Palmer (LANL)
on behalf of the Swift team:
At 01:51:44 UT, Swift-BAT triggered and located GRB050904 (trigger=153514).
The spacecraft slewed immediately. The BAT on-board calculated location
is RA,Dec 13.670d,+14.138d {00h 54m 41s,+14d 08' 17"} (J2000), with an
uncertainty of 3 arcmin (radius, 90% containment, stat+sys). This was a 64-sec
image trigger. The BAT light curve shows hints of emission, but it is
not possible to separate source variations from background variations
at this early stage in the analysis. Given that this is at high galactic
latitude, we believe this is a burst rather than a hard x-ray transient.
There is nothing in SIMBAD nor in the BAT Active Source list near this location.
XRT slewed promptly to the target and observation started at 01:54:25 UT
(T+161 sec) with XRT in auto state. XRT revealed an uncatalogued fading
point source at RA (J2000): 00h 54m 50.4s Dec (J2000): +14d 05' 08.5"
with an uncertainty of 6 arsec (radius), 3.9 arcmin from the BAT position.
The UVOT began observing at 01:54:28 UT, 164 s after the BAT trigger.
The UVOT image is 3 arcmin away from the XRT position, so it does not
intersect the XRT or BAT error circle. We cannot tell whether there
is an optical counterpart at this time.
We are currently in the portion of the orbits where the spacecraft does not
pass over the Malindi downlink station. Therefore, it will be 4 hours
before we have access to the full data set for the refined analyses.
- GCN notice #3911
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We imaged the field of GRB 050904 detected by SWIFT
(trigger 153514) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.
First image was acquired 86s after the GCN trigger.
The field had an elevation of 60 degrees above horizon
and weather conditions were good.
We detected no new source comparing our unfiltered images
with the USNO-B catalog.
From the first frame we give an early limit:
Day : 2005-09-04
UT-start UT-end (sec since GRB) Exp(s) R-mag
01:53:10.33 - 01:54:08.33 86 - 101 15 >16.0
We co-added 13 first frames and no new source
is detected:
Day : 2005-09-04
UT-start UT-end (sec since GRB) Exp(s) R-mag
01:53:10.33 - 02:00:18.74 86 - 515 360 >18.5
Limiting magnitude was estimated with the nearby USNO-B1 stars.
This message can be cited.
- GCN notice #3912
Derek B. Fox (Penn State) and S. Bradley Cenko (Caltech) report on
behalf of a larger collaboration:
"We have imaged the BAT and XRT localization region for GRB050904
(Swift Trigger 153514; Cummings et al., GCN 3910) in a series of
exposures with the Palomar Robotic 60-inch Telescope (P60). At the
following mean epochs, and to the following limits in R- and i-band,
we identify no new sources within the XRT localization region in our
coadded images:
Time (UT) Delta Limit (mag)
===================================
05:25 +3h33m R > 20.8
05:41 +3h49m i > 19.7
===================================
Our photometric calibration is performed against the USNO-B1.0 catalog
R-band and I-band magnitudes for this field for our R- and i-filter
images, respectively.
Our observations of this field are continuing."
- GCN notice #3913
J. Haislip, D. Reichart, E. Cypriano, S. Pizzaro, A. LaCluyze, J. Rhoads,
E. Figueredo report on behalf of the UNC team of the FUN GRB Collaboration.
We imaged the XRT localization of GRB 050904 (Cummings et al., GCN 3910)
with 4.1m SOAR at CTIO beginning about three hours after the burst. We
detect a relatively bright (J ~ 17.5 mag) and fading source within
the XRT error circle:
RA: 00 54 51.3
DEC 14 05 09.7
There is no source at this location in POSS2 or SDSS.
Near-simultaneous imaging with PROMPT reveals no source to about the POSS2
detection limit.
This suggests that the afterglow is either very extinguished or at high
redshift.
- GCN notice #3914
J. Haislip, D. Reichart, E. Cypriano, S. Pizzaro, A. LaCluyze, J. Rhoads,
E. Figueredo report on behalf of the UNC team of the FUN GRB Collaboration.
With SOAR, we have continued to image the NIR afterglow (Haislip et al.,
GCN 3913) of GRB 050904 (Cummings et al., GCN 3910) in JHK. Between 3.0
and 7.4 hours after the burst, we measure the temporal index to be -1.20.
At 7.4 hours after the burst, we measure J - K = 1.2 mag, corresponding to
a spectral index of -0.35.
Scaling the i and R limits of Fox et al. (GCN 3912) to 3.0 hours after the
burst, we measure i - J > 1.85 mag and R - J > 3.05 mag, corresponding to
spectral indexes of <-1.90 and <-3.35, respectively.
This is too steep to be explained by even heavy extinction. If
interpretted as dropout, this corresponds to 5.3 < z < 9.0 (calculated
using filter centers).
Further NIR and especially z observations are strongly encouraged.
- GCN notice #3915
D. Reichart reports on behalf of the UNC team of the FUN GRB Collaboration.
We have computed preliminary error bars on the temporal and spectral
indexes of Haislip et al. (GCN 3914). The temporal index is -1.20 +/- 0.17
and the spectral index is -0.35 +/- 0.33. This disfavors the ISM-RED and
WIND-RED cases at the 2.2 sigma confidence level, the ISM-BLUE case at the
1.3 sigma confidence level, and the WIND-BLUE case only at the 0.3 sigma
confidence level (e.g., Sari, Piran & Narayan 1998; Chevalier & Li 2000).
If the WIND-BLUE case is borne out by further observations, this suggests
an electron-energy distribution index of p = 1.9 +/- 0.2, as well as a
massive-star origin.
If the NIR afterglow is strongly extinguished, and the intrinsic spectrum
is even shallower than -0.35, or even positive, then none of the standard
cases hold. This also suggests that the afterglow is probably not strongly
extinguished, and supports the conclusion of Haislip et al. (GCN 3914) that
the sharp spectral break between the J and i bands is likely due to
dropout.
Furthermore, given that the K to J spectral index is so shallow, and the J
to i spectral index is so steep, the redshift range is probably narrower
than that implied by the J and i filter centers (5.3 < z < 9.0), and is
probably between 6 and 8. Careful modeling will better constrain this, but
z, Z and/or Y observations, preferably contemporaneous with addition NIR
observations would be most useful.
- GCN notice #3916
Dr. D.T. Durig (Cordell-Lorenz Observatory, University of the South),
Dennis Hohman (Stone Edge Observatory) and Aaron Price report on behalf of
the AAVSO International High Energy Network on observations of the field
of GRB050409 (GCN 3910; Cummings et al.).
Durig does not detect any afterglow with SNR>3 on unfiltered images
centered at 08:30:59 UT. However, sources do exist with an SNR=3 at
locations near that reported in GCN #3913 (Haislip et al.). Locations and
magnitude:
00 54 51.38 14 04 48.9 20.0 mag
00 54 50.42 14 05 30.6 20.1 mag
00 54 51.55 14 05 28.8 20.2 mag
Full details, including a link to the FITS image is available at the
bottom of this notice.
Also, Hohman observed the field with an Rc filter centered on 06:18 UT
and does not report any afterglow to Rc=18.6. Details on his observation
are also below.
The AAVSO thanks the Curry Foundataion for their continued
support of the AVSO International High Energy Network.
Report filed on Sun Sep 4 07:54:36 2005:
Name: Dr. D. T. Durig
email: ddurig@sewanee.edu
Observer: D. T. Durig, A. P. Long, A. L. Yacko, J. L. Rouquette, J. C.
Heiss
Site: Cotrdell-Lorenz Observatory
Location: Sewanee, Tenn, USA
LatitudeLongitude: 35 12 N 85 55 W
Elevation: 600m
Scope: SCT 0.30 m
ScopeFocalRatio: f/5.9 1760 mm
CCDVendor: SBIG STL-1001E
CCDDetector: KAF-1001E
CCDSize: 1024x1024
CCDPixelScale: 2.8
CCDFOV: 48x48 full, 12x12 quater shown
Object: GRB050904
ObsDate: 2005 Sept 4
ObsMidPointTime: 08 30 59 UT
TimePerFrame: 300 sec
NumberOfFrames: 37
Filters: CR
Processing: dark, flat, register, add, 1/4 frame crop
Seeing: ~6
LimitingMag: approx. 20.5
Sky: clear but windy
afterglowmag: NA
afterglowerr: NA
compstars: 850 USNO B1.0 in Full Frame
Report: Total exposure 185 minutes (37x300 sec= 11,100 sec ). I see no
afterglow at the reported position(s) above my detection limit but there
appears to be three very dim diffuse sources nearby at
00 54 51.38 14 04 48.9 20.0 mag
00 54 50.42 14 05 30.6 20.1 mag
00 54 51.55 14 05 28.8 20.2 mag
All three are near my limiting mag with sigma equal to 3.
In the noise I measure
00 54 49.69 14 05 08.5 21.9 mag
but with sigma equal to 1.5 and below my detection limit of 20.5 mag.
A FITS image has been uploaded to
ftp://ftp.aavso.org/grb/Dr.D.T.Durig_GRB050904_2453617.99625_.fits
--------------------
Report filed on Sun Sep 4 03:36:21 2005:
Name: Dennis Hohman
email: dennishohman@adelphia.net
Observer: Dennis Hohman HDF
Site: Stone Edge Observatory
Location: Orchard Park, NY USA
LatitudeLongitude: -78 45, 42 46
Elevation: 290M
Scope: C8 200mm
ScopeFocalRatio: 1200
CCDVendor: ST7XME
CCDDetector: KAF402E
CCDSize:
CCDPixelScale: 1.55
CCDFOV: 19x13
Object: GRB050904
ObsDate: 09/04/05
ObsMidPointTime: 06:18
TimePerFrame: 240 sec
NumberOfFrames: 8
Filters: R
Processing: Darks,Flats, bias, coadd
Seeing: 4
LimitingMag: 18.6
Sky: mostly clear with occasional patchy clouds
afterglowmag:
afterglowerr:
compstars:
Report: Full error circle covered. No new object observed to a limiting
magnitude of 18.6 based USNO A2.0 catalog
comments:
A FITS image has been uploaded to
ftp://ftp.aavso.org/grb/DennisHohman_GRB050904_2453617.81691_.fits
- GCN notice #3917
Klotz, A. (CESR-OMP), Boer M. (OHP), Atteia J.L. (LATT-OMP) report:
We did not explore the location of the Haislip
et al. (GCNC 3913) source candidate in the first
analyzis reported in GCNC 3911. This source is
detected in three composited images taken by TAROT
in the 8 first minutes after GRB. Magnitudes are
calculated using the R USNO-B magnitudes of three
nearby stars.
[sec after GRB]
start end magnitude
86 144 R>18.1 +/- 0.3 (no detected)
150 253 R=18.5 +/- 0.3
312 370 R=18.7 +/- 0.3
376 479 R=19.1 +/- 0.4
Corresponding images can be seen at:
http://www.cesr.fr/~klotz/grb050904
After 8 minutes, the CCD camera cooler failed.
Then, images are very noisy. We will try to
obtain corresponding dark frames in the next
days to reprocess images after t_GRB+8 min.
This message can be cited.
- GCN notice #3918
D. Palmer (LANL), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cannizzo (GSFC-UMBC), J. Cummings (GSFC/NRC), D. Hullinger (GSFC/UMD),
E. Fenimore (LANL), N. Gehrels (GSFC), H. Krimm (GSFC/USRA),
C. Markwardt (GSFC/UMD), A. Parsons (GSFC), T. Sakamoto (GSFC/NRC),
G. Sato (ISAS), M. Tashiro (Saitama U.), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
Using only a small amount of the full data set from recent telemetry
downlinks, we report further analysis of Swift-BAT Trigger #153514
(Cummings, et al., GCN 3910). Due to a large backlog in data downlinking,
we have only the data from T-40 to T+120 sec. We do not expect the full
data set for at least another 2 days, so we are issuing this partial report.
The ground-analysis position is RA,Dec 13.722,14.081 {0h54m53s, 14d04'52"}
(J2000) with an uncertainty of 2.6 arcmin (radius, 90%, stat+sys).
This is 3.9 arcmin from the onboard position and 0.54 arcmin from the
IR afterglow position reported by Haislip et al. in GCN Circ. 3913.
This is a long burst with T90 greater than 120 sec. The burst started
at T+0 sec with continued emission past T+120 sec (where the downlinked
data stops).
- GCN notice #3919
J. Haislip, M. Nysewander, D. Reichart, E. Cypriano, D. Maturana, S.
Pizarro, C. MacLeod, J. Kirschbrown, E. Figueredo report on behalf of the
UNC team of the FUN GRB Collaboration.
We continued observations of the afterglow (Haislip et al., GCN 3913) of
GRB 050904 (Cummings et al., GCN 3910) with SOAR and PROMPT at CTIO in YJ
and Ic, respectively, beginning 26.4 hours after the burst.
We detect the afterglow in J and refine the fading rate to be -1.00 +/-
0.12.
We also detect the afterglow in Y, which suggests that the redshift is at
the lower end of the redshift ranges of Haislip et al. (GCN 3914) and
Reichart (GCN 3915).
Furthermore, a redshift of 6 (+/- 1) appears to be consistent with the
relatively faint, unfiltered optical detections of Klotz et al. (GCN 3917)
from only minutes after the burst: Extrapolation of our J-band light curve
back to this time suggests that the afterglow was probably relatively
bright (J ~ 13 mag) redward of the Ly-alpha forest. Integration of the
light across a broad optical spectral response curve would then result in
significantly fainter magnitudes for such redshifts.
- GCN notice #3920
T. Mineo(INAF-IASF), V. Mangano(INAF-IASF), V. La Parola(INAF-IASF),
G. Cusumano (INAF-IASF), L. Angelini (GSFC), J. Cummings (GSFC/NRC),
D. N. Burrows (PSU), F. Marshall (GSFC), P. Boyd (GSFC-UMBC)
report on behalf of the Swift XRT team:
We have analyzed the Swift XRT data from the first observation
of GRB 050904 (Cummings et al. 2005, GCN 3910) consisting
of four orbits (about 20 ks).
The refined coordinates of the X-ray afterglow are:
RA(J2000) = 0h 54m 50.6s
Dec(J2000) = +14d 05' 04.5"
with an estimated uncertainty is of 6 arcseconds radius (90%
containment).
This position is 37 arcsec from the revised BAT position given
in GCN 3918 (Palmer et al. 2005), 4.5 arcseconds from
the XRT position determined on board and 11 arcseconds
from the SOAR position (Haislip et al., GCN 3913).
The 0.2-10 keV light curve, that starts in Windowed Timing (WT) mode
169 seconds after the BAT trigger (T0), shows a fading behaviour.
Moreover two flares are clearly detected in the first orbit:
the first at T0+466 s in WT data and the second at at T0+1240 s
in Photon Counting (PC) mode data.
The light curve decay index, obtained excluding the flare
time intervals, is -2.08+/-0.03.
The remaining three orbits show irregular rate variations
likely due to other flares.
A preliminary spectral fit to WT and PC data of the first orbit,
excluding the flare time intervals, shows an evidence of spectral
evolution from hard to soft:
Time interval(s) Photon Index NHx10^20(cm^-2) Flux(erg cm^-2 s^-1)
T0+170-370 1.33+/-0.04 15+/-1 1.8x10^-9
T0+580-1760 1.70+/-0.08 5.6+/-1.0 4.6x10^-11
The Galactic absorption in the GRB direction is 5x10^20 cm^-2.
I.A.S.F. INAF Mailing System
- GCN notice #3921
P. D'Avanzo (INAF/OAB), L. A. Antonelli (INAF/OAR), S. Covino
(INAF/OAB), D. Malesani (SISSA), G. Tagliaferri, G. Chincarini
(INAF/OAB) on behalf of the MISTICI collaboration report:
We observed the field of GRB 050904 (Cummings et al., GCN 3910), in the
J band with the 3.6m TNG telescope (equipped with NICS) and with the ESO
VLT-UT1 (equipped with ISAAC). We don't detect the NIR source at the
position indicated by Haislip et al. (R.A. 00:54:51.3, Dec. 14:05:09.7,
GCN 3913, 3919) and by Klotz et al. (GCN 3917) to a limit J > 22
(5sigma). We also note that this position is ~ 6 arcsec out from the XRT
error box (Mineo et al., GCN 3920) and ~ 11" away from its center.
We detect however a single fading source inside the XRT error box, which
is likely the NIR counterpart of GRB 050904. Its coordinates are:
R.A.(J2000) = 00:54:50.8
Dec.(J2000) = +14:05:10.0
The detected source faded by 0.30 +/- 0.15 mag between the two epochs
(24.7 and 26 h after the burst, respectively). That source has a J
magnitude which is consistent with the one expected from the source
proposed by Haislip et al. with a decay slope of t^-1,
A finding chart is available at the following URL:
http://www.sissa.it/~malesani/GRB/050904/GRB050904_finder.jpg
We thank the TNG and ESO staff, in particular Marco Pedani, Poshak
Gandhi and Nancy Ageorges for carefully performing our observations and
quickly providing the data.
This message can be cited.
- GCN notice #3922
M. Nysewander, D. Reichart, J. Haislip report on behalf of the UNC GRB team
of the FUN GRB Collaboration:
Using a single 348 sec coadd from last night's SOAR data (Haislip et al.,
GCN 3919) and 7 USNO stars, we measure the coordinates of the afterglow to
be:
RA: 00:54:50.794
DEC: +14:05:09.42
with uncertainties of 1.6" in RA and 2.3" in DEC.
This is consistent with the astrometry of D'Avanzo et al. (GCN 3921) and
the refined coordinates of the X-ray afterglow (Mineo et al.; GCN 3920).
DR apologizes for the crudeness of our initial astrometry.
- GCN notice #3923
A. Cucchiara (PSU), J. Cummings (GSFC), S. Holland (GSFC), C. Gronwall
(PSU),
A. Blustin (MSSL), F. Marshall (GCFS), A. Smale (NASA HQ), L. Cominsky
(Sonoma State U.),
N. Gehrels (GSFC) on behalf of the Swift UVOT team
Swift/UVOT began observing the field of GRB050904 at 01:54:25 UT,
164 s after the BAT trigger (Cummings, et al., GCN 3910) in all the six
filters.
In the first 100 s V-band image (T+ 214 s), no new source is detected with
respect to the DSS down to a 3 sigma upper limit of 18.9 mag in the XRT
error
circle (GCN 3910).
At T+90 min after the trigger, in a single 900 s V-band image the upper
limit
was 20.1.
The instrument continued to collect data during all the other orbits
detecting no new source down to the following upper limits:
Filter Start_Time(UT) Stop_Time(UT) Exp(s) 3sig_limit
V 01:54 16:20 4887 20.9
B 01:56 18:12 4773 21.9
U 01:56 17:57 4686 21.6
UVW1 01:56 16:49 4292 21.1
UVM2 01:56 16:35 4684 21.4
UVW2 01:57 18:26 4331 21.4
Where Start_Time and Stop_Time are the time range over wich the summed
images
were accumulated and Exp is the total exposure time (in seconds) of the
summed image.
The magnitude upper limits are not corrected for extinction.
These non-detections are consistent with a high redshift GRB,
as reported by J. Haislip, et al. (GCN 3914 and 3919).
These magnitudes are based on preliminary zero-points, measured
in orbit, and will require refinement with further calibration.
This message can be cited.
- GCN notice #3924
L.A. Antonelli, A. Grazian (INAF/OAR), P. D'Avanzo (INAF/OABr), V. Testa
(INAF/OAR), S. Covino, G. Tagliaferri, G. Chincarini (INAF/OABr), A.
Fernandez-Soto (Univ. Valencia), D. Malesani (SISSA), F. Fiore and L.
Stella (INAF/OAR) report on behalf of the MISTICI collaboration:
"We observed the field of GRB 050904 (Cummings et al., GCN 3910; Mineo
et al., GCN 3920) with the ESO VLT-UT1, in the J, H, and K bands (with
ISAAC) and in the I band (with FORS2).
The afterglow (Haislip et al., GCN 3913; D'Avanzo et al., GCN 3921) is
detected in all filters, including the I band.
We derive for this source a photometric redshift z = 6.10 (+0.37,
-0.12; 90% confidence) by adopting a chi square minimization technique
(Fontana et al., 2000, AJ, 120, 2206). This is in agreement with the
result of Haislip et al. (GCN 3919).
This message can be cited."
- GCN notice #3925
C. MacLeod, J. Kirschbrown, D. Reichart, E. Cypriano, P. Ugarte, A.
Alvarez, E. Figueredo report on behalf of the UNC team of the FUN GRB
Collaboration.
We continued observations of the afterglow (Haislip et al., GCN 3913) of
GRB 050904 (Cummings et al., GCN 3910) with 4.1m SOAR at CTIO in J,
beginning 52.9 hours after the burst.
The afterglow is no longer detected: J > 21.6 (2 sigma). This implies that
temporal index has steepened from -1.0 +/- 0.1 (Haislip et al., GCN 3919)
to <-2.3 over the past day, which suggests that we are now past the
jet-break time.
- GCN notice #3928
J-L. Atteia (LAT-OMP) communicates:
The high redshift of GRB 050904 suggests a possible interpretation
of the XRT observations reported in GCNC 3920 (T. Mineo et al.) as
the *prompt emission* of the burst.
- The maximum effective area of SWIFT/XRT (2 keV) corresponds to a restframe
energy of ~14 keV for a source at redshift z=6.1.
- The time of the first XRT flare is 466/(7.1) ~ 66 sec in the restframe.
- The spectral index of -1.33 is suggestive of the spectral index of
the prompt emission below the the break energy (Epeak).
All these numbers are compatible with an interpretation of the early
SWIFT/XRT observations in terms of GRB prompt emission.
In view of this possibility, further information on the duration
of GRB 050904, would be of great interest.
- GCN notice #3929
M. Jelinek, A.J. Castro-Tirado, A. de Ugarte Postigo (IAA-CSIC
Granada), P. Kubanek (ASU AV CR Ondrejov), S. Vitek (CVUT
Praha), J. Gorosabel and S. Guziy (IAA-CSIC), R. Hudec (ASU
AV CR), J.M. Castro Ceron (NBI Kobenhavn), P. Pata and M.
Bernas (CVUT),
report:
The BOOTES-1B 30 cm robotic telescope in Southern Spain,
has followed-up the high-redshift GRB 050904 (Cummings et
al. GCN 3910, Antonelli et al. GCN 3924) starting 124s after
the onset of the burst. Our R-band measurements during the
time interval 124s -1100s after the event, together with the
values reported by TAROT (Klotz et al. GCN 3917) are
consistent with an early decay index of alpha = -1.2 (i.e. in
agreement with the value later reported in the J-band by Haislip
et al. GCN 3914).
This message can be quoted.
- GCN notice #3930
P. D'Avanzo (INAF/OABr), L.A. Antonelli(INAF/OAR), S. Covino
(INAF/OABr), A. Grazian, V. Testa (INAF/OAR), D. Malesani (SISSA), D.
Fugazza, G. Tagliaferri (INAF/OABr), G. Chincarini (INAF/OAB & UNIMIB),
L. Stella (INAF/OAR), and A. Fernandez-Soto (Univ. Valencia) report on
behalf of the MISTICI collaboration:
We continued monitoring the afterglow (Haislip et al., GCN 3913;
D'Avanzo et al., GCN 3921) of GRB 050904 (Cummings et al., GCN 3910;
Mineo et al., GCN 3920) with the ESO VLT-UT1 (equipped with ISAAC).
Observations were performed in the J, H, and K bands, at about 50, 51
and 51.5 hours after the burst.
We still detect the afterglow in all filters. The measured magnitudes
are consistent with an unbroken decay with slope ~1 from 3 to ~50 hr
after the GRB.
We thank the ESO staff, in particular Nancy Ageorges for carefully
performing our observations and quickly providing the data.
More observations are planned.
This message can be cited.
- GCN notice #3932
D. Perley, J. S. Bloom, M. Cooper (UCB), J. Newman (LBL), P.
Guhatakurta (UCSC), J. X. Prochaska (UCO Lick) and H.-W. Chen (MIT/U
Chicago) report on behalf of a larger group:
"We observed the field of GRB 050904 (GCN 3910) using the DEIMOS
imager on the Keck II during the early morning twilight of 05 Sept
2005 UT. The afterglow candidate reported by Haislip et al. (GCN
3913, 3922) is well-detected in the first 300-second I-band exposure,
taken at UTC=14:50 (~37.0 hours after the burst). Calibrating
against three nearby stars in SDSS, we measure a preliminary
magnitude for the afterglow of i~=22.9 +/- 0.6. This uncertainty is
dominated by the photometric calibration which we expect to improve
with further processing."
This message may be cited.
- GCN notice #3937
N. Kawai (Tokyo Tech), T. Yamada (NAOJ), G. Kosugi, T. Hattori, and
K. Aoki (Subaru/NAOJ) report on behalf of Subaru GRB team:
"We observed the field of GRB 050904 (GCN 3910) with Faint Object
Camera And Spectrograph on the Subaru 8.2m telescope atop Mauna
Kea on the night of September 6, approximately 3.5 days after the
burst. We obtained spectra of the afterglow candidate (Haislip et
al. GCN 3913, 3922, D'Avanzo et al. GCN 3921).
Based on the absorption features we measure the redshift to be
z=6.29 +- 0.01, confirming the photometoric redshift reported
earlier (Haislip et al. GCN 3914, 3919, Antonelli et al. GCN 3924)."
This message may be cited.
- GCN notice #3938
T. Sakamoto (GSFC/NRC), L. Barbier (GSFC), S. Barthelmy (GSFC),
J. Cummings (GSFC/NRC), D. Hullinger (GSFC/UMD), E. Fenimore (LANL),
N. Gehrels (GSFC), H. Krimm (GSFC/USRA), C. Markwardt (GSFC/UMD),
D. Palmer (LANL), A. Parsons (GSFC), G. Sato (ISAS), J. Tueller (GSFC)
on behalf of the Swift-BAT team:
We now have the complete BAT data for GRB 050904 (Cummings et al.,
GCN circ. 3910 and Palmer et al. GCN circ. 3918). This was a very
long, bright burst. The light curve shows 3 main peaks. There are
15-second long peaks at ~T+28 sec and ~T+56 sec, and the main peak
was from ~T+80 sec to ~T+220 sec, along with weaker peaks. Emission
in the BAT energy range continues to almost T+500 sec with a weak
peak at ~T+470 sec. T90 was 225 +/- 10 sec (estimated error including
systematics, 15-350 keV).
Fitting a simple power law from T+17 sec to T+226 sec, the photon
index is 1.34 +/- 0.06. The fluence is 5.4 +/- 0.2 x 10^6 ergs/cm^2.
The 1-second peak flux from T+27.5 sec is 0.8 +- 0.2 photons/cm^2/sec.
All errors are 90% confidence, energy range 15-150 keV.
Haislip et al. (GNC circ. 3914, 3919) reported a Ly-alpha break for
this burst corresponding to a redshift of 5.3 to 9.0. Antonelli et al.
(GCN circ. 3924) calculate a redshift of 6.1. Kawai et al. (GCN circ.
3937) report a spectrographic redshift of 6.29. With the above fluence
at this redshift (6.29), the isotropic energy equivalent is
3.8 x 10^53 ergs in the range 109 - 1094 keV in the GRB rest frame.
- GCN notice #3939
V.Rumyantsev (CrAO), V.Biryukov (SAI, MSU), A.Pozanenko
(IKI), M. Ibrahimov (MAO) on behalf of larger GRB follow up
collaboration report:
We observed the BAT and XRT error boxes of GRB050904
(Swift # 153514; Cummings et al., GCN 3910) with 2.6m Shain
telescope (CrAO) on September 4 between (UT) 20:39 - 21:31
in R-band filter. The OT (Haislip et al., GCN 3913, D'Avanzo
et al. GCN 3921) is not detected in our combine image.
Preliminary estimation of the limiting value of the
combined image based on USNO-A2.0 catalog is following
Mean time Exposure Filter Magnitude
(UT) s
21:04 24x120 R 23.5
Combined image can be found in
http://grb.rssi.ru/GRB050904
This message may be cited.
- ESO press release 22/05
http://www.eso.org/outreach/press-rel/pr-2005/pr-22-05.html
- astro-ph/0511154 from 5 Nov 2005
Wei: The optical flare and afterglow light curve of GRB 050904 at redshift z=6.29
GRB050904 is very interesting since it is by far the most distant GRB event
known to date($z=6.29$). It was reported that during the prompt high energy
emission phase, a very bright optical flare was detected, and it was temporal
coincident with an X-ray flare. Here we use two models to explain the optical
flare, One is the "late internal shock model", in which the optical flare is
produced by the synchrotron radiation of the electrons accelerated by the late
internal shock, and the X-ray flare is produced by the synchrotron-self-Compton
mechanism. The other is the external forward-reverse shock model, in which the
optical flare is from the reverse shock emission and the X-ray flare is
attributed to the central engine activity. We show that with proper parameters,
a bright optical flare can appear in both models. We think the "late internal
shock model" is more favored since in this model the optical flash and the
X-ray flare have the same origin, which provides a natural explanation of the
temporal coincidence of them. In the forward-reverse shock scenario, fits to
the optical flare and the late afterglow suggests that the physical parameters
of the reverse shock are much different from that of forward shock, as found in
modeling the optical flash of GRB 990123 previously.
- astro-ph/0511205 from 8 Nov 2005
Zou: Is GRB 050904 a super-long burst?
In the basis of the internal shock model and synchrotron radiative process
and under the assumption that all internal shocks are nearly equally energetic,
we analyse the emission at different radii, which correspond to different
observed times. Surprisingly, our analytical results can provide a natural
explanation for the multi-band observations of GRB 050904. This implies that
the violently variated X-ray emission and the optical emission of the burst
originated from internal shocks, with the energy of ejected shells from the
central engine that didn't decrease until the X-ray emission faded away. So we
suggest that GRB 050904 is a burst with super-long central engine activity.
- astro-ph/0512154 from 6 Dec 2005
Totani: Implications for the Cosmic Reionization from the Optical Afterglow Spectrum of the Gamma-Ray Burst 050904 at z = 6.3
The gamma-ray burst (GRB) 050904 at z = 6.3 provides the first opportunity of
probing the intergalactic medium (IGM) by GRBs at the epoch of the
reionization. Here we present a spectral modeling analysis of the optical
afterglow spectrum taken by the Subaru Telescope, aiming to constrain the
reionization history. The spectrum shows a clear damping wing at wavelengths
redward of the Lyman break, and the wing shape can be fit either by a damped Ly
alpha system with a column density of log N_HI ~ 21.6 at a redshift close to
the detected metal absorption lines (z_{metal} = 6.295), or by almost neutral
IGM extending to a slightly higher redshift of z_{IGM,u} ~ 6.36. In the latter
case, the difference from z_{metal} may be explained by acceleration of metal
absorbing shells by the activities of the GRB or its progenitor. However, we
exclude this possibility by using the light transmission feature around the Ly
beta resonance, leading to a firm upper limit of z_{IGM,u} < 6.314. We then
show an evidence that the IGM was largely ionized already at z=6.3, with the
best-fit neutral fraction of IGM, x_HI = 0.00 +- 0.17, and an upper limit of
x_HI < 0.60 (95% C.L.). This is the first quantitative upper limit on x_HI at z
> 6. Various systematic uncertainties are examined, but none of them appears
large enough to change this conclusion. To get further information on the
reionization, it is important to increase the sample size of z >6 GRBs, to find
GRBs with low column densities (log N_HI <~ 20) within their host galaxies, and
for statistical studies of Ly alpha line emission from host galaxies.
- astro-ph/0603431 from 16 Mar 2006
Gendre: The Gamma-ray burst 050904 : a star in the early sky
We present optical and X-ray observations of GRB 050904 obtained with TAROT
and SWIFT. We perform temporal and spectral analysis of the XRT and optical
data. We find evidence for a variable absorption in the early phase of the
afterglow and we interpret this as a progressive photo-ionization. The spectral
properties of the early X-ray flare observed about 460 seconds after the burst
are similar to those of the following afterglow. In the optical band, we
observe a flare simultaneous with the X-ray one. We use the temporal and
spectral information to interpret the data. The overall behavior of the early
afterglow is compatible with a fireball expanding in a wind environment, and
the late optical flattening might be explained by the effect of a termination
shock. To explain the simultaneous X-ray and optical flares we consider the
hypothesis of delayed external shock from a thick shell, inverse Compton
emission from reverse shock, reverse shock from synchrotron emission, inverse
Compton emission from late internal shock or a very long internal shock
activity.
- astro-ph/0603689 from 27 Mar 2006
Berger: HST and Spitzer Observations of the Host Galaxy of GRB 050904: A Metal-Enriched, Dusty Starburst at z=6.295
We present deep Hubble Space Telescope and Spitzer Space Telescope
observations of the host galaxy of GRB 050904 at z=6.295. The host is detected
in the H-band and marginally at 3.6 micron. From these detections, and limits
in the z'-band and 4.5 micron, we infer an extinction-corrected absolute
magnitude, M(UV)=-20.7 mag, or ~L*, a substantial star formation rate of 15
solar masses per year, and a stellar mass of a few 10^9 solar masses. A
comparison to the published sample of spectroscopically-confirmed galaxies at
z>5.5 reveals that the host of GRB 050904 would evade detection and/or
confirmation in any of the current surveys due to the lack of detectable
Ly-alpha emission, which is likely the result of dust extinction (A[1200]~1.5
mag). This suggests that not all luminous starburst galaxies at z~6 are
currently being accounted for. Most importantly, using the metallicity of
Z~0.05 solar inferred from the afterglow absorption spectrum, our observations
indicate for the first time that the observed evolution in the mass- and
luminosity-metallicity relations from z=0 to z~2 continues on to z>6. The ease
of measuring redshifts and metallicities from the afterglow emission suggests
that in tandem with the next generation ground- and space-based telescopes, a
GRB mission with dedicated near-IR follow-up can provide unique information on
the evolution of stars and galaxies through the epoch of re-ionization.
- astro-ph/0606567 from 22 Jun 2006
Kann: The prompt optical/near-infrared flare of GRB 050904: the most luminous transient ever detected
With a redshift of z=6.295, GRB 050904 is the most distant gamma-ray burst
ever discovered. It was an energetic event at all wavelengths and the afterglow
was observed in detail in the near-infrared bands. We gathered all available
optical and NIR afterglow photometry of this GRB to construct a composite NIR
light curve spanning several decades in time and flux density. Transforming the
NIR light curve into the optical, we find that the afterglow of GRB 050904 was
more luminous at early times than any other GRB afterglow in the
pre-Swift era, making it at these wavelengths the most luminous
transient ever detected. Given the intrinsic properties of GRB 050904 and its
afterglow, we discuss if this burst is markedly different from other GRBs at
lower redshifts.
- GCN Circular #5300
F. Walter (MPIA Heidelberg), C. Carilli (NRAO), F. Bertoldi (AIfA Bonn),
A. Weiss (MPIfR Bonn) report:
We observed the host galaxy of GRB 050904 (GCN 3910) at redshift z=6.29
(GCN 3937), RA 00:54:50.83, Dec +14:05:10 (J2000), with the
Max-Planck-Millimeter Bolometer (MAMBO-2) array at the IRAM 30-m telescope
on 27 February 2006 and 03 March 2006, and obtained a non-detection of
S_nu(250 GHz,1.20mm) = -0.76 +/- 0.45 mJy
(1 sigma error), i.e. a 3 sigma upper flux density limit of 1.35 mJy. The
MAMBO-2 bolometer detectors cover 210-290 GHz (half power). The host
galaxy of GRB 050904 is well within our 10.7 arcsec FWHM beam.
This message may be cited.
- Radio detection: Frail et al. 2006, ApJL 646, L99
- astro-ph/0610570 from 18 Oct 2006
Cusumano et al: Swift observations of GRB050904: the most distant cosmic
explosion ever observed
Swift discovered the high redshift (z=6.29) GRB050904 with the Burst Alert
Telescope (BAT) and began observing with its narrow field instruments 161 s
after the burst onset. This gamma-ray burst is the most distant cosmic
explosion ever observed. Because of its high redshift, the X-ray Telescope
(XRT) and BAT simultaneous observations provide 4 orders of magnitude of
spectral coverage (0.2-150 keV; 1.4-1090 keV in the source rest frame) at a
very early source-frame time (22 s). GRB050904 was a long, multi-peaked, bright
GRB with strong variability during its entire evolution. The light curve
observed by the XRT is characterized by the presence of a long flaring activity
lasting up to 1-2 hours after the burst onset in the burst rest frame, with no
evidence of a smooth power-law decay following the prompt emission as seen in
other GRBs. However, the BAT tail extrapolated to the XRT band joins the XRT
early light curve and the overall behavior resembles that of a very long GRB
prompt. The spectral energy distribution softens with time, with the photon
index decreasing from -1.2 during the BAT observation to -1.9 at the end of the
XRT observation. The dips of the late X-ray flares may be consistent with an
underlying X-ray emission arising from the forward shock and with the
properties of the optical afterglow reported by Tagliaferri et al. (2005b). We
interpret the BAT and XRT data as a single continuous observation of the prompt
emission from a very long GRB. The peculiarities observed in GRB050904 could be
due to its origin within one of the first star-forming regions in the Universe;
very low metallicities of the progenitor at these epochs may provide an
explanation.
- astro-ph/0611305 from 9 Nov 2006
Campana: A metal rich molecular cloud surrounds GRB 050904 at redshift 6.3
GRB050904 is the gamma-ray burst with the highest measured redshift. We
performed time resolved X-ray spectroscopy of the late GRB and early afterglow
emission. We find robust evidence for a decrease with time of the soft X-ray
absorbing column. We model the evolution of the column density due to the flash
ionization of the GRB and early afterglow photons. This allows us to constrain
the metallicity and geometry of the absorbing cloud. We conclude that the
progenitor of GRB050904 was a massive star embedded in a dense metal enriched
molecular cloud with Z~0.03 Z_solar. This is the first local measurement of
metallicity in the close environment of a GRB and one of the highest redshift
metallicity measurements. We also find that the dust associated with the cloud
cannot be similar to that of our Galaxy but must be either sizably depleted or
dominated by silicate grains. We discuss the implications of these results for
GRB progenitors and high redshift star formation.
- astro-ph/0612256 from 11 Dec 2006
Gou: Modeling GRB 050904: Autopsy of a Massive Stellar Explosion at z=6.29
GRB 050904 at redshift z=6.29, discovered and observed by Swift and with
spectroscopic redshift from the Subaru telescope, is the first gamma-ray burst
to be identified from beyond the epoch of reionization. Since the progenitors
of long gamma-ray bursts have been identified as massive stars, this event
offers a unique opportunity to investigate star formation environments at this
epoch. Apart from its record redshift, the burst is remarkable in two respects:
first, it exhibits fast-evolving X-ray and optical flares that peak
simultaneously at t~470 s in the observer frame, and may thus originate in the
same emission region; and second, its afterglow exhibits an accelerated decay
in the near-infrared (NIR) from t~10^4 s to t~3 10^4 s after the burst,
coincident with repeated and energetic X-ray flaring activity. We make a
complete analysis of available X-ray, NIR, and radio observations, utilizing
afterglow models that incorporate a range of physical effects not previously
considered for this or any other GRB afterglow, and quantifying our model
uncertainties in detail via Markov Chain Monte Carlo analysis. In the process,
we explore the possibility that the early optical and X-ray flare is due to
synchrotron and inverse Compton emission from the reverse shock regions of the
outflow. We suggest that the period of accelerated decay in the NIR may be due
to suppression of synchrotron radiation by inverse Compton interaction of X-ray
flare photons with electrons in the forward shock; a subsequent interval of
slow decay would then be due to a progressive decline in this suppression. The
range of acceptable models demonstrates that the kinetic energy and circumburst
density of GRB 050904 are well above the typical values found for low-redshift
GRBs.
- astro-ph/0612367 from 14 Dec 2006
Aoki: Search for the host galaxy of GRB 050904 at z=6.3
We present the results of deep imaging of the field of GRB 050904 with
Suprime-Cam on the Subaru 8.2m telescope. We have obtained a narrow-band (130
A) image centered at 9200 A (NB921) and an i'-band image with total integration
times of 56700 and 24060 s, respectively. The host galaxy was not detected
within 1'' of the afterglow position. An object was found at 1.5'' NE from the
position of the afterglow, but clear detection of this object in the i'-band
image rules out its association with the burst. We obtained a limit of > 26.4
AB magnitude (2'' diameter, 3 sigma) in the NB921 image for the host galaxy,
corresponding to a flux of 6.0 x 10^{28} erg/s/Hz at rest 1500 A assuming a
flat spectrum of the host galaxy. The star formation rate should be less than
7.5 (M_{solar}/yr) based on the conversion rate by Madau et al (1998). This
upper limit for the host of GRB 050904 is consistent with the star formation
rate of other gamma-ray burst host galaxies around redshift of 2 or less.
- GCN Circular #6018
E. Berger (Carnegie Observatories) reports on behalf of a large
collaboration:
"We re-observed the position of GRB 050904 (z=6.295) with NICMOS on the
Hubble Space Telescope on 2006 July 22 UT. A total of 6 orbits (15360
sec) were obtained with the F160W (H-band) filter. Previous observations
of the burst with NICMOS on 2005 Sep 27 UT revealed a source with
F160W(AB)=26.1+/-0.2 mag (Berger et al. astro-ph/0603689), which was
interpreted as a combination of afterglow and host galaxy light. The new
observations reveal no source at the position of the burst to a 3-sigma
limit of F160W(AB)=27.2 mag. This result indicates that the host galaxy
is fainter than about 0.05 microJy, and that the light contribution from
the afterglow to the source detected in the Sep 2005 observations was
>60%, confirming the proposed jet break at t~3 days (Tagliaferri et al.
2005; Haislip et al. 2006).
A complete analysis of the new NICMOS observations, and their implications
for the afterglow and host galaxy properties, will be made available in a
revised version of astro-ph/0603689."
- astro-ph/0703349 from 14 Mar 2007
Stratta: Dust properties at z=6.3 in the host galaxy of GRB 050904
We investigate the dust extinction properties in the host galaxy of the
Gamma-Ray Burst (GRB) GRB 050904 at z=6.29 by analyzing simultaneous broad band
observations of the optical and UV afterglow at three different epochs. We show
that the peculiar afterglow spectral energy distribution (SED) observed at 0.5
days and at 1 day after the burst (1.6 and 3 hours rest frame) cannot be
explained with dust reddening with any of the extinction curves observed at low
redshift. Yet, the extinction curve recently inferred for the most distant BAL
QSO at z=6.2 nicely reproduces the SED of GRB 050904 at both epochs. Our result
provides an additional, independent indication that the properties of dust
evolve beyond z~6. We discuss the implications of this finding within the
context of the dust production mechanisms through the cosmic ages.
- 1002.4101 from 23 Feb 10
Tayyaba Zafar et al.: No evidence for dust extinction in GRB 050904 at z ~ 6.3
Levan (2), Michal/ J. Michal/owski (1,3) ((1) DARK, (2) Univ. Warwick., (3) Univ. Edinburgh)
Context: GRB afterglows are excellent probes of gas and dust in star-forming galaxies at all epochs. It has been posited that dust in the early
Universe must be different from dust at lower z. To date two reports directly support this contention, one of which is based on the spectral
shape of GRB 050904 at z = 6.295. Aims: We reinvestigate the afterglow to understand dust at high z. We address the claimed evidence for
unusual (SN-origin) dust in its host galaxy by simultaneously examining the X-ray and optical/NIR spectrophotometric data. Methods: We derive
the intrinsic SED of the afterglow at 0.47, 1.25 and 3.4 days, by re-reducing the Swift X-ray data, the 1.25 days FORS2 z-Gunn photometric
data, the spectroscopic and z'-band photometric data at ~3 days from the Subaru telescope, as well as the critical UKIRT Z-band photometry at
0.47 days, upon which the claim of dust detection largely relies. Results: We find no evidence of dust extinction in the SED. We compute flux
densities at lambda_rest = 1250 AA directly from the observed counts at all epochs. In the earliest epoch, 0.47 days, the Z-band suppression is
found to be smaller (0.3 +- 0.2 mag) than previously reported and statistically insignificant (<1.5 sigma). Furthermore we find that the
photometry of this band is unstable and difficult to calibrate. Conclusions: From the afterglow SED we demonstrate that there is no evidence
for dust extinction -- the SED at all times can be reproduced without dust, and at 1.25 days in particular, significant extinction can be
excluded, with A(3000 AA) < 0.27 mag at 95% confidence using the SN-type extinction curve. We conclude that there is no evidence of any
extinction in the afterglow of GRB 050904 and that the presence of SN-origin dust in the host of GRB 050904 must be viewed skeptically.
[abridged]
- 1101.1503 from 10 Jan 11
Tayyaba Zafar et al.: Exploring dust extinction at the edge of reionization
((1) DARK, (2) Univ. Leicester, (3) Univ. Warwick)
The brightness of gamma-ray burst (GRB) afterglows and their occurrence in young, blue galaxies make them excellent probes to study star
forming regions in the distant Universe. We here elucidate dust extinction properties in the early Universe through the analysis of the
afterglows of all known z > 6 GRBs: GRB 090423, 080913 and 050904, at z = 8.2, 6.69, and 6.295, respectively. We gather all available optical
and near-infrared photometry, spectroscopy and X-ray data to construct spectral energy distributions (SEDs) at multiple epochs. We then fit the
SEDs at all epochs with a dust-attenuated power-law or broken power-law. We find no evidence for dust extinction in GRB 050904 and GRB 090423,
with possible evidence for a low level of extinction in GRB 080913. We compare the high redshift GRBs to a sample of lower redshift GRB
extinctions and find a lack of even moderately extinguished events (AV ~ 0.3) above z > 4. In spite of the biased selection and small number
statistics, this result hints at a decrease in dust content in star-forming environments at high redshifts.
- 1201.6383 from 1 Feb 12
S. Basa et al.: Constraining the nature of the most distant Gamma-Ray Burst host galaxies
Long duration Gamma-Ray Bursts (GRBs) allow us to explore the distant Universe, and are potentially the best tracer of the most distant
objects. Our current knowledge of the properties of GRB host galaxies at redshifts > 5 is very scarce, and more observations of high-redshift
hosts are required to better understand their properties and the implications of using GRBs as probes of the high-redshift universe. We
performed very deep photometric observations of three high-redshift GRB host galaxies, GRB 080913 at z = 6.7, GRB 060927 at z = 5.5 and GRB
060522 at z = 5.1. Our FORS2 and HAWK-I observations at the VLT targeted the rest-frame UV continuum of these galaxies, allowing us to
constrain their star formation rates. In addition, we performed deep spectroscopic observations of the GRB080913 host galaxy with X-Shooter at
the VLT to search for Ly-{\alpha} emission. For the sake of the discussion, we make use of published results on another GRB host, GRB 050904 at
z = 6.3. The sample of GRB host galaxies studied in this paper consists of 4 out of the 6 spectroscopically confirmed GRB host galaxies at z >
5. Despite being the deepest observations ever reported of high-redshift GRB host galaxies, we do not detect any of the hosts, neither in
photometry nor in spectroscopy in the case of GRB 080913. These observations indicate that the GRB host galaxies seem to evolve with time and
to have lower star formation rates (SFR) at z > 5 than they have at z < 2. In addition, the host galaxy of GRB 080913 at z = 6.7 does not show
Ly-{\alpha} emission. While the measured properties of the galaxies in our sample are in agreement with the properties of the general galaxy
population at z > 5, our observations are not sensitive enough to allow us to infer further conclusions on whether this specific population is
representative of the general one.
- 1304.2793 from 11 Apr 13
D. A. Badjin et al.: Thermal Emission in Gamma-Ray Burst Afterglows
We study thermal emission from circumstellar structures heated by gamma-ray burst (GRB) radiation and ejecta and calculate its contribution to
GRB optical and X-ray afterglows using the modified radiation hydro-code small STELLA. It is shown that thermal emission originating in heated
dense shells around the GRB progenitor star can reproduce X-ray plateaus (like observed in GRB 050904, 070110) as well as deviations from a
power law fading observed in optical afterglows of some GRBs (e.g. 020124, 030328, 030429X, 050904). Thermal radiation pressure in the heated
circumburst shell dominates the gas pressure, producing rapid expansion of matter similar to supenova-like explosions close to opacity or
radiation flux density jumps in the circumburst medium. This phenomenon can be responsible for so-called supernova bumps in optical afterglows
of several GRBs. Such a `quasi-supernova' suggests interpretation of the GRB-SN connection which does not directly involve the explosion of the
GRB progenitor star.
- 1503.01118 from 5 Mar 15
Q. Ma et al.: PopIII signatures in the spectra of PopII/I GRBs
We investigate signatures of population III (PopIII) stars in the metal-enriched environment of GRBs originating from population II-I (PopII/I)
stars by using abundance ratios derived from numerical simulations that follow stellar evolution and chemical enrichment. We find that at
$z>10$ more than $10%$ of PopII/I GRBs explode in a medium previously enriched by PopIII stars (we refer to them as GRBII$\rightarrow$III).
Although the formation of GRBII$\rightarrow$III is more frequent than that of pristine PopIII GRBs (GRBIIIs), we find that the expected
GRBII$\rightarrow$III observed rate is comparable to that of GRBIIIs, due to the usually larger luminosities of these latter.
GRBII$\rightarrow$III events take place preferentially in small proto-galaxies with stellar masses $\rm M_\star \sim 10^{4.5} - 10^7\,\rm
M_\odot$, star formation rates $\rm SFR \sim 10^{-3}-10^{-1}\,\rm M_\odot/yr$ and metallicities $Z \sim 10^{-4}-10^{-2}\,\rm Z_\odot$. On the
other hand, galaxies with $Z < 10^{-2.8}\,\rm Z_\odot$ are dominated by metal enrichment from PopIII stars and should preferentially host
GRBII$\rightarrow$III. Hence, measured GRB metal content below this limit could represent a strong evidence of enrichment by pristine stellar
populations. We discuss how to discriminate PopIII metal enrichment on the basis of various abundance ratios observable in the spectra of GRBs'
afterglows. By employing such analysis, we conclude that the currently known candidates at redshift $z\simeq 6$ -- i.e. GRB 050904
PopIII stars.
- 1512.07808 from 25 Dec 15
J. T. W. McGuire et al.: Detection of three Gamma-Ray Burst host galaxies at $z\sim6$
Gamma-ray bursts allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their immense luminosities and
association with deaths of massive stars. We present {\em Hubble Space Telescope} Wide Field Camera 3 detections of three {\em Swift} GRBs
lying at redshifts $z = 5.913$ (GRB 130606A), $z = 6.295$ (GRB 050904), and $z = 6.327$ (GRB 140515A) in the F140W (wide-$JH$ band,
$\lambda_{\rm{obs}}\sim1.4\,\mu m$) filter. The hosts have magnitudes (corrected for Galactic extinction) of $m_{\rm{\lambda_{obs},AB}}=
26.26^{+0.12}_{-0.14}, 27.63^{+0.16}_{-0.18},$ and $28.23^{+0.24}_{-0.30}$ respectively. In all three cases the probability of chance
coincidence of lower redshift galaxies is $\lesssim1.5\%$, indicating that the detected galaxies are most likely the GRB hosts. These are the
first detections of high redshift ($z > 5$) GRB host galaxies in emission. The galaxies have luminosities in the range $0.1-0.7\,L^{*}_{z=6}$
(with $M_{1600}^{*}=-20.95\pm0.12$), along with half-light radii in the range $0.6-1.2\,\rm{kpc}$. Both their half-light radii and luminosities
are consistent with existing samples of Lyman-break galaxies at $z\sim6$. Spectroscopic analysis of the GRB afterglows indicate low
metallicities ($[\rm{M/H}]\lesssim-1$) and dust extinction ($A_{\rm{V}}\lesssim0.1$) along the line of sight. We consider the implications of
these luminosities for their possible star formation histories and the potential for emission line metallicity determinations with {\em James
Webb Space Telescope} spectroscopy.
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