The 2175 Å Dust Feature in a Gamma-Ray Burst Afterglow at Redshift 2.45

By T. Krühler, A. Yoldas, J. Greiner, C. Clemens, S. McBreen, N. Primak, S. Savaglio, G. Szokoly, S. Klose. 2008

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We present optical and near-infrared photometry of the afterglow of the long gamma-ray burst (GRB) 070802 at redshift 2.45 obtained with the ESO/MPI 2.2 m telescope equipped with the multichannel imager GROND. Follow-up observations in g'r'i'z' and JHKS bands started at ~17 minutes and extended up to 28 hr postburst. We find an increase in the brightness of the afterglow at early times, which can be explained by the superposition of reverse and forward shock (FS) emission or the onset of the afterglow FS. In addition, we detect a strong broadband absorption feature in the i' band, which we interpret as extinction from the redshifted 2175 Å bump in the GRB host galaxy. This is one of the first and clearest detections of the 2175 Å feature at high redshift. It is strong evidence for a carbon-rich environment, indicating that Milky Way- or Large Magellanic Cloud-like dust was already formed in substantial amounts in a galaxy at z = 2.45.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/f0312ae207dfee15e9c90f59ce0d9ff09f58e716

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Citations in the corpus

The SEDs and host galaxies of the dustiest GRB afterglows (2011, methodology): “All optical (GROND, EFOSC, FORS1/2) and near-infrared (GROND, SOFI, HAWK-I, ISAAC) imaging was reduced in a standard manner using pyraf/IRAF (Tody 1993) similar to the procedure outlined in Krühler et al. (2008).”
LOW-RESOLUTION SPECTROSCOPY OF GAMMA-RAY BURST OPTICAL AFTERGLOWS: BIASES IN THE SWIFT SAMPLE AND CHARACTERIZATION OF THE ABSORBERS (2009, methodology): “The spe -trum is remarkable is showing a strong 2175 Å dust extin tion feature at the GRB redshift of z = 2.45 (see also Krühler et al. 2008).”
GRB hosts through cosmic time - VLT/X-Shooter emission-line spectroscopy of 96 γ-ray-burst-selected galaxies at 0.1 (2015, methodology): “Data reduction and photometry follow the procedures established in Krühler et al. (2008) in the former case and is taken from the Keck GRB Host Survey (Perley et al. 2013a) in the latter case.”
The Cow: Discovery of a Luminous, Hot, and Rapidly Evolving Transient (2018, methodology): “The optical and NIR data were calibrated using SDSS and 2MASS stars (Krühler et al. 2008).”
THE HOST GALAXIES OF SWIFT DARK GAMMA-RAY BURSTS: OBSERVATIONAL CONSTRAINTS ON HIGHLY OBSCURED AND VERY HIGH REDSHIFT GRBs (2009, background): “Similarly, Swift bursts GRB 050401 (Watson et al. 2006) and GRB 070802 (Krühler et al. 2008) were also “dark” events that were nevertheless sufficiently optically luminous to enable multiband photometry and optical spectroscopy, confirming the link between optical suppression (darkness),…”
THE FIRST POSITIVE DETECTION OF MOLECULAR GAS IN A GRB HOST GALAXY (2009, background): “Wobs values determined from boxcar integrations have no value listed. galaxy (Krühler et al. 2008; Eĺıasdóttir et al. 2008); and (iii) the data favor a low c4 value suggesting few small dust grains.”
A POPULATION OF MASSIVE, LUMINOUS GALAXIES HOSTING HEAVILY DUST-OBSCURED GAMMA-RAY BURSTS: IMPLICATIONS FOR THE USE OF GRBs AS TRACERS OF COSMIC STAR FORMATION (2013, methodology): “GRB 070802 The relatively faint, red afterglow of this event was observed by several telescopes including GROND on the ESO/MPG 2.2 m, which detected the afterglow in all seven filters from g though K (Krühler et al. 2008).”