{
  "bibcode": "2023GCN.33578....1B",
  "body": "M. Bulla, A.E. Camisasca, C. Guidorzi (Ferrara U.), L. Amati, A. Rossi \n(INAF-OAS), G. Stratta, P. Singh (Goethe U. Frankfurt) on behalf of a \nlarger collaboration report: We compared kilonova models computed with \nthe latest version of the radiative transfer code POSSIS (Bulla 2023, \nMNRAS, 520, 2558) to photometric data of a faint source associated with \nGRB 230307A as reported by Levan et al. (GCN 33569). Assuming a redshift \nz=0.065 (Gillanders et al. GCN 33485) and a Galactic extinction of \nE(B-V)=0.0743 mag (Schlafly & Finkbeiner 2011, ApJ, 737, 103), we find a \nreasonably good match to observations in both the F150W and F444W \nfilters for a model viewed along the jet axis (face-on) and with two \nejecta components: 1) a dynamical ejecta component with a mass of 0.005 \nMsun, an average velocity of 0.25c and an average electron fraction \nYe=0.15; 2) and a disk-wind ejecta component with a mass of 0.05 Msun, \nan average velocity of 0.1c and an average electron fraction Ye=0.3 (see \nfigure at the link below). This supports the claim of kilonova emission \nby Levan et al. (GCN 33569) and strengthens the interpretation of GRB \n230307A as a merger event, as also suggested by the properties of the \ngamma-ray prompt emission (Camisasca et al. GCN 33577). Further analysis \nis ongoing. Figure: \nhttps://drive.google.com/file/d/1XhpfwCXQxWWS_G7WQ1fUSZKSiZXnwXiJ/view?usp=sharing",
  "circularId": 33578,
  "createdOn": 1680792082000,
  "email": "guidorzi@fe.infn.it",
  "subject": "GRB 230307A: good match with kilonova models",
  "submitter": "Cristiano Guidorzi at Ferrara U,Italy  <guidorzi@fe.infn.it>",
  "eventId": "GRB 230307A"
}