THE LIGHT CURVE OF THE MACRONOVA ASSOCIATED WITH THE LONG–SHORT BURST GRB 060614

The Swift-detected GRB 060614 was a unique burst that straddles an imaginary divide between long- and short-duration gamma-ray bursts (GRBs), and its physical origin has been heavily debated over the years. Recently, a distinct, very soft F814W-band excess at t similar to 13.6 days after the burst was identified in a joint-analysis of VLT and Hubble Space Telescope optical afterglow data of GRB 060614, which has been interpreted as evidence for an accompanying macronova (also called a kilonova). Under the assumption that the afterglow data in the time interval of 1.7-3.0 days after the burst are due to external FS emission, when this assumption is extrapolated to later times it is found that there is an excess of flux in several multi-band photometric observations. This component emerges at similar to 4 days after the burst, and it may represent the first time that a multi-epoch/band light curve of a macronova has been obtained. The macronova associated with GRB 060614 peaked at t less than or similar to 4 days after the burst, which is significantly earlier than that observed for a supernova associated with a long-duration GRB. Due to the limited data, no strong evidence for a temperature evolution is found. We derive a conservative estimate of the macronova rate of similar to 16.3(8.2)(+16.3) Gpc(-3) yr(-1), implying a promising prospect for detecting the gravitational wave radiation from compact-object mergers by upcoming Advanced LIGO/VIRGO/KAGRA detectors (i.e., the rate is R-GW similar to 0.5(-0.25)(+0.5)(D/200 Mpc)3 yr(-1)).

[1]  P. Harding,et al.  SHORT GRB 130603B: DISCOVERY OF A JET BREAK IN THE OPTICAL AND RADIO AFTERGLOWS, AND A MYSTERIOUS LATE-TIME X-RAY EXCESS , 2013, 1309.7479.

[2]  M. Livio,et al.  Nucleosynthesis, neutrino bursts and γ-rays from coalescing neutron stars , 1989, Nature.

[3]  Jesper Sollerman,et al.  No supernovae associated with two long-duration γ-ray bursts , 2006, Nature.

[4]  A. J. Levan,et al.  XRF 100316D/SN 2010bh AND THE NATURE OF GAMMA-RAY BURST SUPERNOVAE , 2011, 1104.5141.

[5]  Bing Zhang,et al.  The physics of gamma-ray bursts & relativistic jets , 2014, 1410.0679.

[6]  D. A. Kann,et al.  The Fast Evolution of SN 2010bh associated with GRB 100316D , 2011, Proceedings of the International Astronomical Union.

[7]  D. Kasen,et al.  OPACITIES AND SPECTRA OF THE r-PROCESS EJECTA FROM NEUTRON STAR MERGERS , 2013, 1303.5788.

[8]  P. Giommi,et al.  A short γ-ray burst apparently associated with an elliptical galaxy at redshift z = 0.225 , 2005, Nature.

[9]  B. Metzger,et al.  Red or blue? A potential kilonova imprint of the delay until black hole formation following a neutron star merger , 2014, 1402.4803.

[10]  S. R. Kulkarni.  Modeling Supernova-like Explosions Associated with Gamma-ray Bursts with Short Durations , 2005 .

[11]  S. B. Pandey,et al.  Swift observations of GRB 060614: an anomalous burst with a well behaved afterglow , 2007, 0704.2235.

[12]  Masaru Shibata,et al.  PRODUCTION OF ALL THE r-PROCESS NUCLIDES IN THE DYNAMICAL EJECTA OF NEUTRON STAR MERGERS , 2014, 1402.7317.

[13]  T. Piran,et al.  Gamma-ray bursts as the death throes of massive binary stars , 1992, astro-ph/9204001.

[14]  K. Hotokezaka,et al.  RADIATIVE TRANSFER SIMULATIONS OF NEUTRON STAR MERGER EJECTA , 2013, 1306.3742.

[15]  T. Piran,et al.  Implications of GRB 130603B and its macronova for r-process nucleosynthesis , 2014, 1401.2166.

[16]  N. T. Zinner,et al.  Electromagnetic counterparts of compact object mergers powered by the radioactive decay of r‐process nuclei , 2010, 1001.5029.

[17]  J. Lippuner,et al.  r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE , 2015, 1508.03133.

[18]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[19]  Bing Zhang,et al.  A SUPRAMASSIVE MAGNETAR CENTRAL ENGINE FOR GRB 130603B , 2013, 1311.7185.

[20]  T. Piran.  The physics of gamma-ray bursts , 2004, astro-ph/0405503.

[21]  E. Berger,et al.  THE LOCATIONS OF SHORT GAMMA-RAY BURSTS AS EVIDENCE FOR COMPACT OBJECT BINARY PROGENITORS , 2013, 1307.0819.

[22]  K. Hotokezaka,et al.  RADIOACTIVELY POWERED EMISSION FROM BLACK HOLE–NEUTRON STAR MERGERS , 2013, 1310.2774.

[23]  Tsvi Piran,et al.  Jets in Gamma-Ray Bursts , 1999 .

[24]  K. Ioka,et al.  ISOTROPIC DETECTABLE X-RAY COUNTERPARTS TO GRAVITATIONAL WAVES FROM NEUTRON STAR BINARY MERGERS , 2015, 1506.02030.

[25]  E. Berger,et al.  AN r-PROCESS KILONOVA ASSOCIATED WITH THE SHORT-HARD GRB 130603B , 2013, 1306.3960.

[26]  E. Berger,et al.  HUBBLE SPACE TELESCOPE OBSERVATIONS OF SHORT GAMMA-RAY BURST HOST GALAXIES: MORPHOLOGIES, OFFSETS, AND LOCAL ENVIRONMENTS , 2009, 0909.1804.

[27]  Douglas P. Finkbeiner,et al.  MEASURING REDDENING WITH SLOAN DIGITAL SKY SURVEY STELLAR SPECTRA AND RECALIBRATING SFD , 2010, 1012.4804.

[28]  K. Ioka,et al.  Dynamical mass ejection from black hole-neutron star binaries , 2015, 1502.05402.

[29]  P. Jakobsson,et al.  THE HIGHLY ENERGETIC EXPANSION OF SN 2010bh ASSOCIATED WITH GRB 100316D , 2011, 1111.4527.

[30]  J. P. Osborne,et al.  Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs , 2008, 0812.3662.

[31]  K. S. Thorne,et al.  Predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors , 2010, 1003.2480.

[32]  Li-Xin Li,et al.  Transient Events from Neutron Star Mergers , 1998 .

[33]  N. M. Brown,et al.  Prospects for Observing and Localizing Gravitational-Wave Transients with Advanced LIGO and Advanced Virgo , 2013, Living Reviews in Relativity.

[34]  D. Wanderman,et al.  The rate, luminosity function and time delay of non-Collapsar short GRBs , 2014, 1405.5878.

[35]  E. Berger,et al.  THE STELLAR AGES AND MASSES OF SHORT GAMMA-RAY BURST HOST GALAXIES: INVESTIGATING THE PROGENITOR DELAY TIME DISTRIBUTION AND THE ROLE OF MASS AND STAR FORMATION IN THE SHORT GAMMA-RAY BURST RATE , 2010, 1009.1147.

[36]  Jennifer Barnes,et al.  EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS , 2013, 1303.5787.

[37]  Stefano Covino,et al.  A possible macronova in the late afterglow of the long–short burst GRB 060614 , 2015, Nature Communications.

[38]  S. Rosswog,et al.  The long-term evolution of neutron star merger remnants { II. Radioactively powered transients , 2013, 1307.2943.

[39]  P. T. O'Brien,et al.  IN SEARCH OF PROGENITORS FOR SUPERNOVALESS GAMMA-RAY BURSTS 060505 AND 060614: RE-EXAMINATION OF THEIR AFTERGLOWS , 2008, 0812.0979.

[40]  K. Ioka,et al.  ENERGY SOURCES AND LIGHT CURVES OF MACRONOVAE , 2014, 1410.0966.

[41]  D. Fugazza,et al.  An enigmatic long-lasting γ-ray burst not accompanied by a bright supernova , 2006, Nature.

[42]  E. Berger.  Short-Duration Gamma-Ray Bursts , 2013, 1311.2603.

[43]  E. O. Ofek,et al.  A novel explosive process is required for the γ-ray burst GRB 060614 , 2006, Nature.

[44]  A. Wolszczan,et al.  THE 5 GHz ARECIBO SEARCH FOR RADIO FLARES FROM ULTRACOOL DWARFS , 2013, 1306.1152.

[45]  S. Rosswog,et al.  Mergers of Neutron Star-Black Hole Binaries with Small Mass Ratios: Nucleosynthesis, Gamma-Ray Bursts, and Electromagnetic Transients , 2005, astro-ph/0508138.

[46]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[47]  Bing Zhang,et al.  Making a Short Gamma-Ray Burst from a Long one: Implications for the Nature of GRB 060614 , 2007 .

[48]  Yuichiro Sekiguchi,et al.  PROGENITOR MODELS OF THE ELECTROMAGNETIC TRANSIENT ASSOCIATED WITH THE SHORT GAMMA RAY BURST 130603B , 2013, 1310.1623.

[49]  S. Rosswog,et al.  On the astrophysical robustness of the neutron star merger r-process , 2012, 1206.2379.