M. Bayliss

Publications (4)6.02 Total impact

• Article: GRB 060121: Implications of a Short-/Intermediate-Duration γ-Ray Burst at High Redshift

  A. de Ugarte Postigo, A. J. Castro-Tirado, S. Guziy, J. Gorosabel, G. Jóhannesson, M. A. Aloy, S. McBreen, D. Q. Lamb, N. Benitez, M. Jelínek, [......], G. Gómez, R. López, T. Q. Donaghy, Y. E. Nakagawa, T. Sakamoto, G. R. Ricker, F. R. Hearty, M. Bayliss, G. Gyuk, and D. G. York
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  ABSTRACT: Since the discovery of the first short-population γ-ray burst (GRB) afterglows in 2005, the handful of observed events have been found to be embedded in nearby (z < 1), bright underlying galaxies. We present multiwavelength observations of GRB 060121, the first short burst observed to clearly outshine its host galaxy (by a factor >102). A photometric redshift for this event places the progenitor at a most probable redshift of z = 4.6, with a less probable scenario of z = 1.7. In either case, GRB 060121 could be the farthermost short-population GRB detected to date and implies an isotropic-equivalent energy release in gamma rays comparable to that seen in long-population bursts. We discuss the implications of the released energy on the nature of the progenitor. These results suggest that GRB 060121 may belong to a family of energetic short-population events, lying at z > 1 and whose optical afterglows would outshine their host galaxies, unlike the first short GRBs observed in 2005. The possibility of GRB 060121 being an intermediate-duration burst is also discussed.
  The Astrophysical Journal 12/2008; 648(2):L83. · 6.02 Impact Factor
• Source

  Available from: Eiji Nakagawa

  Article: GRB 060121: Implications of a Short/Intermediate Duration Gamma-Ray Burst at High Redshift

  A. de Ugarte Postigo, A. J. Castro-Tirado, S. Guziy, J. Gorosabel, G. Johannesson, M. A. Aloy, S. McBreen, D. Q. Lamb, N. Benitez, M. Jelinek, [......], G. Gomez, R. Lopez, T. Q. Donaghy, Y. E. Nakagawa, T Sakamoto, G. R. Ricker, F. R. Hearty, M. Bayliss, G. Gyuk, D. G. York
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  ABSTRACT: Since the discovery of the first short-hard gamma-ray burst afterglows in 2005, the handful of observed events have been found to be embedded in nearby (z < 1), bright underlying galaxies. We present multiwavelength observations of the short-duration burst GRB 060121, which is the first observed to clearly outshine its host galaxy (by a factor >10^2). A photometric redshift for this event places the progenitor at a most probable redshift of z = 4.6, with a less probable scenario of z = 1.7. In either case, GRB 060121 could be the farthermost short-duration GRB detected to date and implies an isotropic-equivalent energy release in gamma-rays comparable to that seen in long-duration bursts. We discuss the implications of the released energy on the nature of the progenitor. These results suggest that GRB 060121 may belong to a family of energetic short-duration events, lying at z > 1 and whose optical afterglows would outshine their host galaxies, unlike the first short-duration GRBs observed in 2005. The possibility of GRB 060121 being an intermediate duration burst is also discussed.
  06/2006;
• Source

  Available from: Eduardo Cypriano

  Article: Discovery and identification of the very high redshift afterglow of GRB 050904

  J. Haislip, M. Nysewander, D. Reichart, A. Levan, N. Tanvir, S. Cenko, D. Fox, P. Price, A. Castro-Tirado, J. Gorosabel, [......], A. Gal-Yam, M. Kasliwal, R. Hudec, S. Vitek, P. Kubanek, J. Crain, A. Foster, M. Bayliss, J. Clemens, J. Bartelme
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  ABSTRACT: In 2000, Lamb and Reichart predicted that gamma-ray bursts (GRBs) and their afterglows occur in sufficient numbers and at sufficient brightnesses at very high redshifts (z > 5) to eventually replace quasars as the preferred probe of element formation and reionization in the early universe and to be used to characterize the star-formation history of the early universe, perhaps back to when the first stars formed. Here we report the discovery of the afterglow of GRB 050904 and the identification of GRB 050904 as the first very high redshift GRB. We measure its redshift to be 6.39(+0.11,-0.12), which is consistent with the reported spectroscopic redshift (6.29 +/- 0.01). Furthermore, just redward of Ly-alpha the flux is suppressed by a factor of three on the first night, but returns to expected levels by the fourth night. We propose that this is due to absorption by molecular hydrogen that was excited to rovibrational states by the GRB's prompt emission, but was then overtaken by the jet. Now that very high redshift GRBs have been shown to exist, and at least in this case the afterglow was very bright, observing programs that are designed to capitalize on this science will likely drive a new era of study of the early universe, using GRBs as probes. Comment: Submitted to Nature, 11 pages, 3 figures, LaTeX
  09/2005;
• Source

  Available from: arxiv.org

  Article: PROMPT: Panchromatic Robotic Optical Monitoring and Polarimetry Telescopes

  D. Reichart, M. Nysewander, J. Moran, J. Bartelme, M. Bayliss, A. Foster, J.C. Clemens, P. Price, C. Evans, J. Salmonson, S. Trammell, B. Carney, J. Keohane, R. Gotwals
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  ABSTRACT: Funded by $1.2M in grants and donations, we are now building PROMPT at CTIO. When completed in late 2005, PROMPT will consist of six 0.41-meter diameter Ritchey-Chretien telescopes on rapidly slewing mounts that respond to GRB alerts within seconds, when the afterglow is potentially extremely bright. Each mirror and camera coating is being optimized for a different wavelength range and function, including a NIR imager, two red-optimized imagers, a blue-optimized imager, an UV-optimized imager, and an optical polarimeter. PROMPT will be able to identify high-redshift events by dropout and distinguish these events from the similar signatures of extinction. In this way, PROMPT will act as a distance-finder scope for spectroscopic follow up on the larger 4.1-meter diameter SOAR telescope, which is also located at CTIO. When not chasing GRBs, PROMPT serves broader educational objectives across the state of North Carolina. Enclosure construction and the first two telescopes are now complete and functioning: PROMPT observed Swift's first GRB in December 2004. We upgrade from two to four telescope in February 2005 and from four to six telescopes in mid-2005. Comment: Accepted to Il Nuovo Cimento, 5 pages, 2 figures, LaTeX (4th Workshop Gamma-Ray Bursts in the Afterglow Era, Rome, 18-22 October 2004)
  02/2005;