[vsnet-grb-info 14246] GRB 060614: theoretical derivation of the redshift and need for deeper search of the host galaxy

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15560
SUBJECT: GRB 060614: theoretical derivation of the redshift and need for deeper search of the host galaxy
DATE:    13/12/02 17:16:04 GMT
FROM:    Remo Rufinni at ICRA  <ruffini at icra.it>

R. Ruffini, C.L. Bianco, M. Enderli, M. Kovacevic, M. Muccino, A.V. Penacchioni, G.B. Pisani, J.A. Rueda, Y. Wang report:

The late X-ray observations of GRB 060614 (A. M. Parsons et al., GCN 5252) by Swift-XRT clearly evidence a pattern typical of a family of GRBs associated to supernova (SN) following the Induced Gravitational Collapse (IGC) paradigm (1,2). By overlapping the X-ray (0.3-10 keV in rest-frame) luminosity light curve of GRB 060614 with the one of GRB 090618, namely the IGC GRB-SN prototype (3), we estimate a theoretical redshift of z=1.2 (see Fig. 1 http://www.icranet.org/images/GCN/GRB060614_Fig1.pdf), much higher than z=0.125 of the purported host galaxy (Price et al., GCN 5275; Fugazza et al., GCN 5276). This leads to the explanation of the absence of a visible SN (4,5,6), settling a long lasting dispute of a possible wrong redshift estimation given by a chance superposition of GRB 060614 with its purported host galaxy (7). GRB 060614 is therefore a canonical IGC GRB-SN system. We note that this new value of the redshift still marginally fulfills the Amati relation (see Fig. 2!
  http://www.icranet.org/images/GCN/GRB060614_Fig2.pdf), and that it is in agreement with z=1.45+/-0.85 given by the Atteia relation (A. Pelangeon & J-L. Atteia, GCN 5265) and with the observational limit of z<1.3 (99.99% CL) given by the combined ultraviolet/optical and X-ray spectra (8).

More optical observations in the GRB field are encouraged for the investigation of the actual host galaxy.


References:
(1) J. A. Rueda & R. Ruffini, ApJLett, 758, L7 (2012)
(2) G. B. Pisani et al., A&A, 552, L5 (2013)
(3) L. Izzo et al., A&A, 548, L5 (2012)
(4) M. Della Valle et al., Nature, 444, 1050-1052 (2006)
(5) J. P. U. Fynbo et al., Nature, 444, 1047-1049 (2006)
(6) A. Gal-Yam et al., Nature, 444, 1053-1055  (2006)
(7) B. E. Cobb et al., ApJ, 651, L85-L88 (2006)
(8) N. Gehrels et al., Nature, 444, 1044-1046 (2006)