- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 19 Aug 02 14:58:31 UT
NOTICE_TYPE: HETE S/C_Alert
TRIGGER_NUM: 2275, Seq_Num: 1
GRB_DATE: 12505 TJD; 231 DOY; 02/08/19
GRB_TIME: 53855.82 SOD {14:57:35.82} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 225 [cnts/s] on a 0.160 [sec] timescale
SC_LONG: 148 [deg East]
SUN_POSTN: 148.69d {+09h 54m 46s} +12.70d {+12d 41' 46"}
MOON_POSTN: 290.10d {+19h 20m 24s} -24.96d {-24d 57' 38"}
MOON_ILLUM: 89 [%]
COMMENTS: No s/c ACS pointing info available yet.
COMMENTS: Probable GRB.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 19 Aug 02 16:35:41 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 2275, Seq_Num: 3
GRB_DATE: 12505 TJD; 231 DOY; 02/08/19
GRB_TIME: 53855.82 SOD {14:57:35.82} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 225 [cnts/s] on a 0.160 [sec] timescale
SC_-Z_RA: 149 [deg]
SC_-Z_DEC: 11 [deg]
SC_LONG: 148 [deg East]
WXM_CNTR_RA: 351.780d {+23h 27m 07s} (J2000),
351.813d {+23h 27m 15s} (current),
351.144d {+23h 24m 35s} (1950)
WXM_CNTR_DEC: +6.364d {+06d 21' 50"} (J2000),
+6.379d {+06d 22' 43"} (current),
+6.089d {+06d 05' 19"} (1950)
WXM_MAX_SIZE: 14.00 [arcmin] diameter
WXM_LOC_SN: 14 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 13.6 Y= 6.3 [sig/noise]
WXM_LC_SN: X= 9.7 Y= 9.1 [sig/noise]
SUN_POSTN: 148.69d {+09h 54m 46s} +12.70d {+12d 41' 46"}
SUN_DIST: 150.14 [deg]
MOON_POSTN: 290.10d {+19h 20m 24s} -24.96d {-24d 57' 38"}
MOON_DIST: 67.66 [deg]
MOON_ILLUM: 89 [%]
GAL_COORDS: 88.50,-50.78 [deg] galactic lon,lat of the burst
ECL_COORDS: 354.99,9.10 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: WXM error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
- GCN/BACODINE POSITION NOTICE
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Mon 19 Aug 02 17:54:08 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 2275, Seq_Num: 4
GRB_DATE: 12505 TJD; 231 DOY; 02/08/19
GRB_TIME: 53855.82 SOD {14:57:35.82} UT
TRIGGER_SOURCE: Trigger on the 25-400 keV band.
GAMMA_RATE: 225 [cnts/s] on a 0.160 [sec] timescale
SC_-Z_RA: 149 [deg]
SC_-Z_DEC: 11 [deg]
SC_LONG: 148 [deg East]
SXC_CNTR_RA: 351.849d {+23h 27m 24s} (J2000),
351.882d {+23h 27m 32s} (current),
351.213d {+23h 24m 51s} (1950)
+6.284d {+06d 17' 01"} (current),
+5.994d {+05d 59' 37"} (1950)
SXC_MAX_SIZE: 4.33 [arcmin] diameter
SXC_LOC_SN: 8 sig/noise (pt src in image)
SUN_POSTN: 148.69d {+09h 54m 46s} +12.70d {+12d 41' 46"}
SUN_DIST: 150.14 [deg]
MOON_POSTN: 290.10d {+19h 20m 24s} -24.96d {-24d 57' 38"}
MOON_DIST: 67.67 [deg]
MOON_ILLUM: 89 [%]
GAL_COORDS: 88.52,-50.90 [deg] galactic lon,lat of the burst
ECL_COORDS: 355.01,8.99 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: SXC error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
COMMENTS: SXC data refined since S/C_Last Notice.
- red DSS finding chart
ps-file
The large circle is the WXM error box of 7 arcmin radius, the small circle
in the lower left corner the SXC position with the 2 arcmin error circle.
- GCN notice #1506
P.A. Price (RSAA, ANU) and R. McNaught (AAO) report:
We have observed the SXC error-circle of HETE trigger #2275 with the
SSO 40-inch telescope + CCD imager commencing at Aug 19.754 UT. Our
3x300 sec exposures cover the entire error-circle to a limiting magnitude
of R ~ 20.5 mag. We do not detect any obvious afterglow candidate upon
visual comparison with the DSS-2 red. Further observations are underway.
- GCN notice #1507
K. Hurley and T. Cline, on behalf of the Ulysses GRB team, and
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, S. Woosley, J. Doty, R.
Vanderspek, J. Villasenor, G. Crew, G. Monnelly, N. Butler, J.G.
Jernigan, A. Levine, F. Martel, E. Morgan, G. Prigozhin, J. Braga, R.
Manchanda, G. Pizzichini, Y. Shirasaki, C. Graziani, M. Matsuoka, T.
Tamagawa, K. Torii, T. Sakamoto, A. Yoshida, E. Fenimore, M. Galassi,
T. Tavenner, T. Donaghy, M. Boer, J-F Olive, and J-P Dezalay, on behalf
of the HETE GRB team, report:
Ulysses and HETE observed this burst (HETE 2275, 53855 s). As observed
by Ulysses, it had a duration of ~20 s, a 25-100 keV fluence of
~7.8E-06 erg/cm2, and a peak flux of ~7.0E-07 erg/cm2 s over 0.25
s.
We have triangulated it to a preliminary, 3 sigma annulus centered
at RA, Decl (2000)=345.048 o, -43.013 o, with radius 49.664 +/- 0.033
degrees. This annulus intersects the HETE WXM position (Sequence
4) at just two points, reducing its area only slightly:
RA DEC
23 h 27 m 29.39 s 6 o 17' 47.58"
23 h 27 m 19.78 s 6 o 18' 3.95"
A map will be posted shortly at ssl.berkeley.edu/ipn3/020819.
This annulus may be improved; it may become an error box when
the Mars Odyssey data become available.
- GCN notice #1508
GRB020819(=H2275): A Long Burst Localized by the HETE WXM and SXC
R. Vanderspek, J. Villasenor, J.G. Jernigan, G. Monnelly, J. Doty, G.
Crew, N. Butler, T. Cline, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini,
on behalf of the HETE Optical-SXC and HETE Operations Teams;
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of
the HETE Science Team;
Y. Shirasaki, C. Graziani, M. Matsuoka, T. Tamagawa, K. Torii, T.
Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T.
Donaghy, on behalf of the HETE WXM Team;
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE
FREGATE Team;
write:
At 14:57:35.82 UTC (53855.82 s UT) on 19 Aug 2002, the HETE FREGATE,
WXM, and SXC instruments detected event H2275, a moderately bright,
long GRB. In the FREGATE 8-40 keV band, the burst had a duration of
~20 seconds, and a peak brightness of ~5x Crab. A GCN Burst Alert
Notice was disseminated 55s after the burst. No real-time optical
camera aspect was generated at the time of the burst; thus, no WXM
real-time localization could be disseminated. Ground analysis of the
optical camera data, and of the WXM data for the burst, produced a
refined location which was reported in a GCN Position Notice issued
98 minutes after the burst. The WXM location can be expressed as a
90% confidence circle that is 7 arcminutes in radius and is centered
at
WXM: RA = 23h 27m 07s, Dec = +6o 21' 50" (J2000).
Ground analysis of the SXC data for the burst also produced a refined
location, which was reported in a GCN Position Notice issued 176
minutes after the burst. The SXC location can be expressed as a 90%
confidence circle that is 130 arcseconds in radius and is centered at
SXC: RA = 23h 27m 24s, Dec = +6o 16' 08" (J2000).
We note that the SXC error circle (reported at 17:54:08 UTC) lies
almost fully within the subsequently-reported IPN annulus (Hurley et
al, GCN1507, issued at 19:30:40 UTC). Also, the catalogued X-ray
source 1RXS J232705.9+062419 lies within the WXM error box, but is
not within the SXC error box.
Further information (including a light curve and the error boxes) for
GRB020819 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/
This message is citable.
The sky map for GRB020819 (H2275). Shown are the error circles from
the WXM, the SXC, and the annulus calculated by the IPN using HETE and
Ulysses data.
- GCN notice #1509
A. Piccioni, C. Bartolini, I. Bruni, R. Gualandi., A. Guarnieri
(Bologna University and Bologna Astronomical Observatory), and
G. Pizzichini (IASF-CNR, Sezione di Bologna) report:
On 2002 August 19, 22h16m17s UT we started observations of the
error box of GRB 020819 (GCN 1468) with the 152 cm telescope in
Loiano. The acquisition sequence was: R band, 1x600 + 3x900 sec
exposures; V band, 1x900 sec; I band, 1x900 sec; B band, 1x1200
sec; R band, 3x900 sec.
By visual inspection in our R frames there is no new object
brighter than the limit of DssII, in accordance with Price P.A.
and McNaught R.
Image reductions and further observations are in progress.
Our images can be retrieved by sftp at 'ermione.bo.astro.it',
username 'publicGRB', password 'GRB_bo', starting on August 21.
This message may be cited.
- GCN notice #1510
A. Henden (USRA/USNO),
J. Greiner (MPE Garching),
S. Klose (Thueringer Landessternwarte Tautenburg),
N. Cardiel, J. Gallego, U. Thiele (Calar Alto Observatory),
D. H. Hartmann (Clemson University),
F. J. Vrba (USNO),
A.J. Castro-Tirado (LAEFF-INTA Madrid and IAA-CSIC Granada),
E. Pian (INAF, Astr. Obs. Trieste), and
G. Tovmassian (OAN Ensenada, Mexico)
report on behalf of the GRACE collaboration:
The 130 arcsec radius error circle of the HETE burst GRB 020819 (HETE
trigger #2275, Seq_4; Vanderspek et al. GCN #1508) was imaged in the
K' band on August 19/20, 23:12 UT - 0:33 UT (about 9 hrs after the
burst), using the Calar Alto 3.5-m telescope equipped with the Omega
Prime near-infrared camera (1k x 1k; FOV 6.8 x 6.8 arcmin). The
integration time was 63 min. The limiting magnitude is about K'=20
(+/-0.5), the seeing was about 1.5 arcsec.
Based on a visual comparison with the corresponding DSS2 red image we
find a best afterglow candidate at coordinates
RA, DEC (J2000) = 23:27:31.5, 6:14:59, +/- 1 arcsec.
This source is relatively bright in K' (we can only provide a very
rough estimate at the moment; K' = 17.5 +/- 1) but has no counterpart on
the DSS 2 red image. We stress that we cannot yet rule out that this a
red foreground star. Naturally, there are several more, progressively
fainter, objects that are also potential candidates.
Further NIR observations are needed in order to search for a fading
behaviour.
- Finding chart associated to GCN #1510
The error circle represents the 130 arcsec radius HETE-SXC error, and the
object marked by two dashes is the afterglow candidate as mentioned in
GCN #1510.
- GCN notice #1511
P.A. Price (RSAA, ANU), D.W. Fox (Caltech), A. Piccioni, C. Bartolini,
I. Bruni, R. Gualandi., A. Guarnieri (Bologna University and Bologna
Astronomical Observatory), G. Pizzichini (IASF-CNR, Sezione di Bologna)
and R. McNaught (RSAA, ANU) report:
We observed the SXC error-circle of GRB 020819 (GCN #1508) with the
Palomar 60-inch telescope at Aug 20.34 UT with 4x600 sec exposures in R.
Comparison of this combined image with those from the SSO 40-inch
telescope (GCN #1506) and the Loiano 1.5-metre telescope (GCN #1509),
both visually and through image subtraction do not reveal any afterglow
candidates. We estimate the limiting magnitudes to be as follows:
SSO 40-inch R ~ 20.5 mag (GCN #1506)
Loiano 1.5-metre R ~ 21.7 mag (GCN #1509)
Palomar 60-inch R ~ 21.5 mag
Comparison of the best NIR afterglow candidate (GCN #1510) with other
sources in the field suggests that this candidate is likely constant in
flux.
This message may be cited.
- GCN notice #1512
Evert Rol, Isabel Salamanca (University of Amsterdam, Netherlands),
Maureen van den Berg, Jeroen Homan (Osservatorio Astronomico di Brera,
Itlay), Lex Kaper (UvA, NL), Nial Tanvir (University of Hertfordshire,
UK) Andrew Levan and Ingunn Burud (STScI, US) on behalf of a larger
collaboration, report:
We have observed the error box of GRB 020819 with the CCD camera in
the JKT at La Palma on August 19/20. The filter was R Harris. We
obtained three sets of exposures at the beginning (2250 sec), middle
(3000 sec) and end (2250 sec) of the night. The limiting magnitude is
about R~22 for the first epoch.
We detect the OT candidate reported by Henden et al (GCN 1510) at
magnitude R ~ 21, but it does not fade from the beginning (UT ~ 23.814
hours) to the end (UT ~ 5.365 hours) of the night.
- GCN notice #1516
Y. Urata, K. Tarusawa, T. Soyano
on behalf of the KISO GRB Team report:
"We have observed the entire HETE-2 SXC error circle of GRB020819
(Vanderspek et al., GCN1508) with the KISO observatory 1.05m schmidt
telescope starting at Aug 19.747 UT. A combined image of all
exposures (3x300sec) gives limiting magnitude of R ~ 19 mag using r
magnitudes of near USNO_A2.0 stars as photometric
references. Comparison with DSS II red images, no new object was
detected down to the limiting magnitude. Also, the candidate reported
by Henden et al. (GCN1510) was not detected."
This message may be cited.
- GCN notice #1517
Andrew Levan, Ingunn Burud, Andy Fruchter, James Rhoads (STScI)
Maureen van den Berg, Jeroen Homan (Osservatorio Astronomico di Brera,
Itlay), Evert Rol (University of Amsterdam, Netherlands) and
Nial Tanvir (University of Hertfordshire, UK) on behalf of a larger
collaboration, report:
The error box of GRB 020819 was observed on August 19 at the JKT (La
Palma) beginning at 23.814, 8.9 hours after burst. R band
observations in three epochs were obtained as described by Salamanca
et al (GCN 1512), these observations reach a limiting magnitude shown
below
Start time (UT) Exp. Time R_lim
23:32:30.117 2250 22.15
01:59:32.974 3000 22.30
05:04:11.925 1500 21.75
(The exposure time is shorter in the third epoch since one of the
frames was contaminated by a satellite track and was not used for
detailed analysis).
Comparison shows no new object brighter than the DSS-2 limit
in any exposure. Confirming the results of GCN 1506 and GCN
1509.
Combined images from each of the three epochs of observations were
subtracted using the method of Alard (Alard, 2000, A&AS, 144, 363).
The subtraction residuals were found to be of order 3% for
bright (though not saturated) objects. For fainter objects the
detection is limited by the noise in the image. With the exception of
the faintest objects the limit on the fading detection is ~0.1 mags.
We find that no objects in the frame exhibit variability beyond the
systematic errors for the entire period of the observation (5.365
hours).
We would like to thank L. Strolger for allowing us use his software
for image registration and subtraction.
- GCN notice #1520
S. Klose (Thueringer Landessternwarte Tautenburg),
A. Henden (USRA/USNO),
J. Greiner (MPE Garching),
D. H. Hartmann (Clemson University),
N. Cardiel, J. Gallego (Universidad Complutense de Madrid), and
U. Thiele (Calar Alto Observatory)
report:
A deep second epoch K' band observation of the 130 arcsec radius error
circle of the HETE burst GRB 020819 (HETE trigger #2275, Seq_4;
Vanderspek et al. 2002, GCN #1508) has been performed on August 20/21,
23:11--00:59 UT (about 33 hrs after the GRB), using the Calar Alto
3.5-m telescope equipped with the Omega Prime near-infrared camera.
The integration time was 77 min. The limiting magnitude is about
K'=20.5 (+/-0.5), the seeing was 1.2 arcsec.
Lacking a K band photometric calibration, we used the (B-R) colors of all
USNO stars (Monet et al. 1996;
http://asteroid.lowell.edu/cgi-bin/koehn/webnet)
in the field for a rough calibration. Assuming their colors are
representative for their spectral type and assuming zero interstellar
extinction, the magnitude of the candidate object reported in GCN #1510
(Henden et al. 2002) is found to have K'=17.6 (conservative error of 0.2 mag).
Photometry of all objects within the HETE/SXC error circle using PSF fitting
(Sextractor) did not reveal any source brighter than K'=19 which faded by
more than 0.1 mag between the first epoch (Henden et al. 2002, GCN #1510)
and this second epoch observation. This and the findings of Price et al.
2002 (GCN #1511) and Salamanca et al. 2002 (GCN #1512) imply that the
candidate object proposed earlier (Henden et al. 2002, GCN #1510) is very
unlikely the GRB afterglow.
- GCN notice #1523
T. Kawabata (BAO), Y. Urata (Titech / RIKEN) report:
We have obtained the R band images of the entire HETE-2 SXC error circle
of GRB020819 (Vanderspek et al., GCN #1508) with the Bisei Astronomical
Observatory (BAO) 1.01-m telescope starting at Aug. 19 18:34 UT (3.6 hrs
after the burst). The limiting magnitude of a combined image of 35
frames (FOV 7.8'x5.2', each exposure time 90 seconds) is R~20.6 (3 sigma,
compared with USNO-A2.0 red magnitudes). We could not find a new object
in the error circle by the comparison with DSS II red image.
This message may be cited.
- GCN notice #1526
GRB020819(=H2275): Revised Localization with HETE Soft X-ray Camera (SXC)
G. Crew, J.G. Jernigan, R. Vanderspek, J. Villasenor, G. Monnelly, J.
Doty, N. Butler, T. Cline, A. Levine, F. Martel, E. Morgan, G.
Prigozhin, G. Azzibrouck, J. Braga, R. Manchanda, and G. Pizzichini,
on behalf of the HETE Optical-SXC and HETE Operations Teams;
G. Ricker, J-L Atteia, N. Kawai, D. Lamb, and S. Woosley on behalf of
the HETE Science Team;
C. Graziani, Y. Shirasaki, M. Matsuoka, T. Tamagawa, K. Torii, T.
Sakamoto, A. Yoshida, E. Fenimore, M. Galassi, T. Tavenner, and T.
Donaghy, on behalf of the HETE WXM Team;
M. Boer, J-F Olive, J-P Dezalay, and K. Hurley on behalf of the HETE
FREGATE Team;
write:
Analysis of the full data set derived from the HETE Soft X-ray Camera
(SXC) has resulted in a revised location for GRB020819(=H2275;
Vanderspek et al, GCN Circular #1508). The revised SXC location can
be expressed as a 90% confidence circle that is 64" in radius and is
centered at:
RA = 23h 27m 25.1s, Dec = +6o 16' 46" (J2000)
This revised SXC localization lies fully within the original 130"
radius SXC error circle reported by Vanderspek et al in GCN1508, as
well as fully within the annulus for the IPN location reported by
Hurley et al in GCN1507.
Further information regarding GRB020819 is provided at the following URL:
http://space.mit.edu/HETE/Bursts/
This message is citable.
- GCN notice #1842
D. A. Frail (NRAO), and E. Berger (Caltech) report on behalf of a
larger collaboration:
"We have continued to monitor the HETE burst GRB020819 with the VLA at
8.46 GHz. Two radio sources were identified within the initial
130-arcsec error circle of the SXC (GCN1508). The first source has
remained constant (within the radiometric errors) at about 380 uJy.
The second source has declined from a peak of 315 uJy on 2002 August
21.37 UT and is currently undetectable (i.e. <35 uJy).
The variable source, located at r.a.=23:27:19.475, dec.=06:15:55.95
(epoch J2000) with conservative errors of +/-0.5 arcsec, is 98-arcsec
away from the center of the revised SXC 64-arcsec error circle
(GCN1526). From previous radio afterglow searches we note that the
probability of detecting such extreme variability from non-GRBs is
rare (<2% probability over the area surveyed). We request observers to
re-examine this position for an optical afterglow.
The entire radio dataset can be found at:
http://www.aoc.nrao.edu/~dfrail/grb_public.shtml
An 8.46 GHz light curve is at
http://www.aoc.nrao.edu/~dfrail/g020819_lcx.ps
This message may be quoted."
- GCN notice #1844
Andrew Levan (U. Leicester/STScI), Andrew Fruchter, James Rhoads and
Ingunn Burud (STScI), Evert Rol, Isabel Salamanca, Lex Kaper (U.
Amsterdam) and Nial Tanvir (U. Hertfordshire) report for a larger
collaboration:
We have re-examined R-band images of the field of GRB 020819 taken with
the JKT on Aug 19th 2002 and with CTIO-4m on Sept 9th 2002. Coincident
with the radio position reported by Frail & Berger (GCN 1842) we find a
clearly resolved galaxy with R~19.8.
A PSF matched image subtraction reveals no evidence of fading between
19th Aug. and 9th Sept. Thus any optical transient had R>22 at the time
of the JKT observations (9 hours after burst).
If this galaxy is indeed the host of GRB 020819 then it is the brightest
GRB host galaxy yet observed (with the exception of the host of GRB
980425/SN1998bw). It may therefore be at very low redshift. Alternatively
the unusual properties of the burst may be related to an unusual host
environment.
- GCN notice #1859
Y. Urata, K. Tarusawa, T. Soyano on behalf of the Kiso GRB team:
"We have observed the field of GRB020819 with the KISO observatory
1.05m schmidt telescope starting at Aug 19.747 UT (2.9 hour after the
burst). We obtained R and I band data with 300 sec x 4 frames and
three 300 sec x 3 frames respectively.
We could not identify any stellar object at the position of radio
afterglow (RA) reported by Frail & Berger (GCN 1842). The R band
limiting magnitude is 18.9 mag. It was estimated by comparison with
field photometry ( Dr. Levan ; private communication). For I band
data, because there are no field photometry, we can not estimate the
limiting magnitude.
Following the DSS-II red image (Plate ID = A0J7), we found that a
faint object is located at near the RA position. The coordinate is
RA=23:27.20 DEC=+06:15:53 measured by using WCS of the image.
We thank to Dr. Levan for R band field photometry."
This message may be cited.
- redshift determination
z=0.41 of host and radio afterglow (Jakobsson et al: ApJ, astro-ph/0505035)
ApJ 629, 45
- Note added Sep 14, 2006 (after repeated
inqueries):
Though most papers in the literature design this burst as GRB 020819, it IS
in fact GRB 020819B. GRB 020819A was detected by IPN satellites at
Earth crossing time = 28601 sec, while H2275 = GRB 020819B was
detected at Earth crossing time = 53856 sec.
See K. Hurley's page
http://www.ssl.berkeley.edu/ipn3/masterli.txt for details.
- 1001.0970 from 8 Jan 10
Emily M. Levesque et al.: A High-Metallicity Host Environment for the Long-Duration GRB 020819
We present spectroscopic observations of the host galaxy and explosion site of the long-duration gamma-ray burst GRB 020819. We determine a
metallicity for this host environment of log(O/H) + 12 = 9.0 +/- 0.1, by far the highest metallicity determined for a long-duration GRB to
date. We compare the metallicity and other properties of the GRB 020819 host environment to existing observations of long-duration GRB host
galaxies, and consider the implications that this metallicity has for our understanding of long-duration GRB progenitor scenarios. We also
consider how this unusually high metallicity may relate to the status of GRB 020819 as a "dark" burst, with no detected optical afterglow.
- 1511.00667 from 3 Nov 15
J. F. Graham et al.: High Metallicity LGRB Hosts
We present our imaging and spectroscopic observations of the host galaxies of two dark long bursts with anomalously high metallicities, LGRB
051022 and LGRB 020819B, which in conjunction with another LGRB event with an optical afterglow comprise the three LGRBs with high metallicity
host galaxies in the Graham & Fruchter (2013) sample. In Graham & Fruchter (2013), we showed that LGRBs exhibit a strong and apparently
intrinsic preference for low metallicity environments (12+log(O/H) < 8.4 in the KK04 scale) in spite of these three cases with abundances of
about solar and above. These exceptions however are consistent with the general star-forming galaxy population of comparable brightness &
redshift. This is surprising: even among a preselected sample of high metallicity LGRBs, were the metal aversion to remain in effect for these
objects, we would expect their metallicity to still be lower than the typical metallicity for the galaxies at that luminosity and redshift.
Therefore we deduce that it is possible to form an LGRB in a high metallicity environment although with greater rarity.
From this we conclude that there are three possible explanations for the presence of the LGRBs observed in high metallicity hosts as seen to
date: (1) LGRBs do not occur in high metallicity environments and those seen in high metallicity hosts are in fact occurring in low metallicity
environments that have become associated with otherwise high metallicity hosts but remain unenriched. (2) The LGRB formation mechanism while
preferring low metallicity environments does not strictly require it resulting in a gradual decline in burst formation with increasing
metallicity. (3) The typical low metallicity LGRBs and the few high metallicity cases are the result of physically different burst formation
pathways with only the former affected by the metallicity and the later occurring much more infrequently.
- 1606.08285 from 28 Jun 16
Jochen Greiner et al.: Probing dust-obscured star formation in the most massive Gamma-Ray Burst host galaxies
Due to their relation to massive stars, long-duration gamma-ray bursts (GRBs) allow pinpointing star formation in galaxies independently of
redshift, dust obscuration, or galaxy mass/size, thus providing a unique tool to investigate the star-formation history over cosmic time. About
half of the optical afterglows of long-duration GRBs are missed due to dust extinction, and are primarily located in the most massive GRB
hosts. In order to understand this bias it is important to investigate the amount of obscured star-formation in these GRB host galaxies. Radio
emission of galaxies correlates with star-formation, but does not suffer extinction as do the optical star-formation estimators. We selected 11
GRB host galaxies with either large stellar mass or large UV-/optical-based star-formation rates (SFRs) and obtained radio observations of
these with the Australia Telescope Compact Array and the Karl Jansky Very Large Array. Despite intentionally selecting GRB hosts with expected
high SFRs, we do not find any star-formation-related radio emission in any of our targets. Our upper limit for GRB 100621A implies that the
earlier reported radio detection was due to afterglow emission. We do detect radio emission from the position of GRB 020819B, but argue that it
is in large parts, if not all, due to afterglow contamination. Half of our sample has radio-derived SFR limits which are only a factor 2--3
above the optically measured SFRs. This supports other recent studies that the majority of star formation in GRB hosts is not obscured by dust.
- 1609.04016 from 15 Sep 16
Daniel A. Perley et al.: A Revised Host Galaxy Association for GRB 020819B: A High-Redshift Dusty Starburst, Not a Low-Redshift Gas-Poor Spiral
The purported spiral host galaxy of GRB 020819B at z=0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray
burst environments: optical spectroscopy of this host provided evidence that GRBs can form even at high metallicities, while millimetric
observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from VLT (MUSE and
X-shooter) which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a
compact, highly star-forming, dusty galaxy at z=1.9621. The revised redshift naturally explains the apparent nondetection of CO(3-2) line
emission at the afterglow site from ALMA. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited
evidence that GRBs can form readily at super-Solar metallicity.
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