1. NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
2. KIPAC, Stanford University, PO Box 20450, MS 29, Stanford, California 94309, USA
3. USRA, NSSTC,
4. NASA/Marshall Space Flight Center, NSSTC, VP-62, 320 Sparkman Drive, Huntsville, Alabama 35805, USA
5. Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
6. Department of Astronomy and Astrophysics,
7. Department of Physics, Pennsylvania State University, Pennsylvania 16802, USA
8. Theoretical Astrophysics, California Institute of Technology, MS 130-33, Pasadena, California 91125, USA
9. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
10. Mullard Space Science Laboratory, University College London, Dorking, RH5 6NT, UK
11. Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
12. Oak Ridge Associated Universities, PO Box 117, Oak Ridge, Tennessee 37831-0117, USA
13. Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904-4325, USA
14. Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, California 95064, USA

Correspondence to: N. Gehrels¹ Correspondence and requests for materials should be addressed to N.G. (Email: gehrels@milkyway.gsfc.nasa.gov).

Abstract

Gamma-ray bursts (GRBs) are known to come in two duration classes¹, separated at 2 s. Long-duration bursts originate from star-forming regions in galaxies², have accompanying supernovae when these are near enough to observe and are probably caused by massive-star collapsars³. Recent observations^{4, 5, 6, 7, 8, 9, 10} show that short-duration bursts originate in regions within their host galaxies that have lower star-formation rates, consistent with binary neutron star or neutron star–black hole mergers^{11, 12}. Moreover, although their hosts are predominantly nearby galaxies, no supernovae have been so far associated with short-duration GRBs. Here we report that the bright, nearby GRB 060614 does not fit into either class. Its 102-s duration groups it with long-duration GRBs, while its temporal lag and peak luminosity fall entirely within the short-duration GRB subclass. Moreover, very deep optical observations exclude an accompanying supernova^{13, 14, 15}, similar to short-duration GRBs. This combination of a long-duration event without an accompanying supernova poses a challenge to both the collapsar and the merging-neutron-star interpretations and opens the door to a new GRB classification scheme that straddles both long- and short-duration bursts.

1. NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771, USA
2. KIPAC, Stanford University, PO Box 20450, MS 29, Stanford, California 94309, USA
3. USRA, NSSTC,
4. NASA/Marshall Space Flight Center, NSSTC, VP-62, 320 Sparkman Drive, Huntsville, Alabama 35805, USA
5. Department of Astronomy, University of Maryland, College Park, Maryland 20742, USA
6. Department of Astronomy and Astrophysics,
7. Department of Physics, Pennsylvania State University, Pennsylvania 16802, USA
8. Theoretical Astrophysics, California Institute of Technology, MS 130-33, Pasadena, California 91125, USA
9. Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
10. Mullard Space Science Laboratory, University College London, Dorking, RH5 6NT, UK
11. Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
12. Oak Ridge Associated Universities, PO Box 117, Oak Ridge, Tennessee 37831-0117, USA
13. Department of Astronomy, University of Virginia, Charlottesville, Virginia 22904-4325, USA
14. Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, California 95064, USA

Correspondence to: N. Gehrels¹ Correspondence and requests for materials should be addressed to N.G. (Email: gehrels@milkyway.gsfc.nasa.gov).

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.