Director’s Colloquium speaker Shrinivas Kulkarni stands below an image of the Compton Gamma Ray Observatory, just prior to its release into orbit by the Space Shuttle Atlantis in April 1991. Four of the eight BATSE GRB detector modules mounted on the satellite are visible at its corners. Photos by LeRoy N. Sanchez, Public Affairs

Kulkarni explores the flashiest of cosmic explosions

Gamma-ray bursts are the “flashiest of cosmic explosions,” according to Shrinivas Kulkarni.

Kulkarni's professional interests are the study of compact objects––neutron stars and gamma-ray bursts (GRBs) ––and the search for extra-solar planets. This work has lead him to believe that gamma-ray bursts mark the death of massive stars and the birth of newly-formed, rapidly spinning black holes.

Kulkarni, a Califorrnia Institute of Technology professor of astronomy and planetary sciences, talked about his research in the field of gamma-ray bursts at a Director’s Colloquium earlier this week at Los Alamos. The Laboratory this year is celebrating 30 years of the discovery of GRBs and sponsored a meeting on these cosmic phenomena this fall in Santa Fe.

Compellingly titled “The Brilliant Gamma-ray Bursts: Death Cries Across the Universe” and laced with bits of self-deprecating humor, Kulkarni’s talk charted the course of gamma-ray burst research since their discovery in the 1960s. Starting with the Laboratory’s early and influential role in their detection with the Vela satellite, he moved through a series of specific gamma-ray burst events that have been influential in his life and in the fields of astronomy and astrophysics.

These GRB events, all numerically named for the year, date and month of their occurrence, can each contribute to advancing our knowledge of the phenomenon, and in doing so, lessen GRBs claim to the title of the “most mysterious objects in the Universe,” Kulkarni said. GRB 970508, for example, was what Kulkarni calls “the golden burst” that provided evidence that GRBs were of an extragalactic origin. On Jan. 23, 1999, afterglow images were captured by ROTSE, a Los Alamos-run robotic optical telescope, of the fading optical counterpart of GBR 990123.

Kulkarni hopes that some of what he called “unconventional telescopes” will help advance the field even further. These are instruments and devices like HETE, Swift, Milagro, GLAST, ICE CUBE and S-AGILE, most of which have involved Los Alamos researchers.

Kulkarni predicts a bright future for the study of GRBs, especially in terms of their use as “cosmological lighthouses.” According to Kulkarni, GRBs might be used to probe the intergalactic medium, to probe the elemental and dust abundance in the disk of cosmological galaxies, as independent measures of obscured fractions of cosmological star formation, and to explore the so-called “Epoch of Reionization.”

Kulkarni provided several reasons why GRBs are of potential interest to both astronomers and physicists alike, but noted that GRB astronomy is a world-wide struggle.” “Bursts,” he says, “are equal opportunity targets for small or large telescopes across the entire electromagnetic spectrum to professionals and amateurs alike.”

For more information on the Director’s Coloquium program, go to http://stb.lanl.gov:8080/wosaserver/web?pg=/program/colloquium/upcoming.xml online.

-- Todd Hanson

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