E. Pian – LNGS, 13 Sep 2005 Elena Pian - INAF, Trieste Astronomical Observatory, Italy LNGS Summer Institute 2005 GRB: Modern Status

E. Pian – LNGS, 13 Sep 2005 Outline Connection between Supernovae and long GRBs / X-ray Flashes Swift: early GRB counterparts Short Gamma-Ray Bursts

E. Pian – LNGS, 13 Sep 2005 Bimodal distribution of GRB durations short long The progenitors of short bursts are still to be identified!!! Binary neutron stars? Kulkarni 2000

E. Pian – LNGS, 13 Sep 2005 Bloom et al. 1998,1999

E. Pian – LNGS, 13 Sep 2005 GRB host galaxies: EW of [O II] emission line Djorgovski 2001 SFR ~ M /yr millimetric: up to ~500 M /yr O II 3727 Å

E. Pian – LNGS, 13 Sep 2005 z = 0.8 GRB (z = 1.6) V ~ 23.5 GRB (z = 0.695) GRB (z = 1.6) V(host) = 28.5 ! GRB z = 0.43

E. Pian – LNGS, 13 Sep 2005 Colors of host galaxies are very blue (compare, e.g., with Hubble Deep Field) Fruchter et al GRB hosts

E. Pian – LNGS, 13 Sep 2005 Schaefer et al Keck LRIS – Mirabal et al. 2003

E. Pian – LNGS, 13 Sep 2005 GRB Supernova 1998bw (Type Ic) z =

E. Pian – LNGS, 13 Sep 2005 GRB030329/SN 2003dh Si II 6355 Hjorth et al z = ESO VLT + FORS Photospheric velocity

E. Pian – LNGS, 13 Sep 2005 GRB021211/SN2002lt Della Valle et al. 2003

E. Pian – LNGS, 13 Sep 2005 Della Valle et al z = d

E. Pian – LNGS, 13 Sep 2005

GRB031202/SN2003lw z = ESO VLT FORS Malesani et al. 2004

E. Pian – LNGS, 13 Sep 2005 z = Galama et al SN1998bw

E. Pian – LNGS, 13 Sep 2005 X-ray Flashes

E. Pian – LNGS, 13 Sep 2005 XRF Fynbo et al Tominaga et al Soderberg et al. 2004

E. Pian – LNGS, 13 Sep 2005 Is there a unifying scheme for SNe and GRBs? Four clear cases of SN-GRB association have been detected spectroscopically, all are Type Ic SNe. In all of these, the SN is very powerful (high luminosity, large kinetic energy), i.e. it is a Hypernova (Paczynski 1998; Iwamoto et al. 1998) The rate of GRBs (taking into account collimation) corresponds to the relative rate of hypernovae with respect to the total number of Ic SNe (i.e. ~5%, Podsiadlowski et al. 2004) SNe with hypernova characteristics have been detected, although they are not accompanied by a GRB (SNe 1997dq, 1997ef, 2002ap, 2004aw…); see also IPN survey Do all hypernovae have jets and produce GRBs, so that only those aligned with the line of sight are detected? Can we test this unified scenario?

E. Pian – LNGS, 13 Sep 2005 Rates of GRBs and HNe These are lower than rate of SNe from massive stars: Podsiadlowski et al. 2004

E. Pian – LNGS, 13 Sep 2005 Type Ic SNe / Hypernovae Broad lines Large Kinetic Energy Hypernovae (only SN1998bw was associated with a GRB) Narrow lines normal KE (1 foe) Normal SN Ic Mazzali et al. 2002

E. Pian – LNGS, 13 Sep 2005 Signatures of asphericity in SN1998bw In nebular spectra of SN1998bw, Fe lines are broader than O lines A spherically symmetric explosion of a massive star would result in the opposite [FeII] 5200A [OI] 6300A SN 1998bw O Fe

E. Pian – LNGS, 13 Sep s 1.5 s 2D explosion : KE=11foe, M BH (final)=5.9M, M( 56 Ni)=0.11M Outflow Inflow Maeda et al. 2002

E. Pian – LNGS, 13 Sep Fe 16 O Spherical Aspherical FeII] 5200A [OI] 6300A SN 1998bw Aspherical explosion: confined nucleosynthesis Orientation 15 deg Maeda et al. 2002

E. Pian – LNGS, 13 Sep 2005 Another GRB/SN: SN2003dh The nebular spectrum shows a strong and narrow [O I]6300 line, like SN1998bw. Narrow-line model: v = 5000 km/s Broad-line model: v = km/s

E. Pian – LNGS, 13 Sep 2005 The bright Type Ic SN 2003jd Courtesy: K. Kawabata Discovered 25 Oct 2003; distance: 80 Mpc

E. Pian – LNGS, 13 Sep 2005 The bright Type Ic SN 2003jd SN 2003jd was as bright at peak as SN1998bw (Mv = -18.7) Early-time spectra had broad lines, similar to hypernova SN2002ap No GRB or XRF

E. Pian – LNGS, 13 Sep 2005 SN 2003jd: The [O I] 6300A line shows a double peak, suggesting an explosion similar to SN1998bw but viewed ~70° from the axis an aspherical SN viewed off-axis Mazzali et al. 2005, Science 308, 1284 Observations: Subaru+FOCAS, at 330 days Keck+LRIS, at 370 days Subaru

E. Pian – LNGS, 13 Sep 2005 Mg I] [Fe II][O I] [Ca II] Subaru+FOCAS Keck+LRIS SN2003jd: an aspherical supernova viewed off-axis Mazzali et al. 2005

E. Pian – LNGS, 13 Sep 2005 [O I] line: strong dependence on viewing angle Mazzali et al [O I] nebular emission

E. Pian – LNGS, 13 Sep 2005 Was SN 2003jd also a GRB/HN? Radio and X-ray upper limits are not in contradiction with a GRB viewed off-axis X-ray radio Mazzali et al. 2005

E. Pian – LNGS, 13 Sep 2005 Swift Launched 20 Nov 2004

E. Pian – LNGS, 13 Sep 2005 Swift localization of GRBs

E. Pian – LNGS, 13 Sep 2005 Steep decline common Gets shallower around here Examples of Swift-XRT light curves Nousek et al. 2005

E. Pian – LNGS, 13 Sep 2005 Maiorano et al GRB Corsi et al WFC PDS MECS 2-10 keV keV

E. Pian – LNGS, 13 Sep 2005 GRB (z = 1.6) Fruchter et al. 1999

E. Pian – LNGS, 13 Sep 2005 GRB041219a: Optical flash from internal shocks Akerlof et al. 1999; Vestrand et al RAPTOR Internal shock ROTSE-I Reverse shock

E. Pian – LNGS, 13 Sep 2005 Optical Flashes Guidorzi et al. 2005

E. Pian – LNGS, 13 Sep 2005 GRB050502a z = Liverpool 2m telescope + Robonet consortium Forward shock in ISM In variable density Environment Guidorzi et al. 2005

E. Pian – LNGS, 13 Sep 2005 BAT+XRT emission consistent with a single decay rate of 1.2± keV X-ray light curve GRB050509b (T 90 =0.04s) Gehrels et al. 2005

E. Pian – LNGS, 13 Sep 2005 Comparison with other X-ray transients

E. Pian – LNGS, 13 Sep 2005 GRB050509b Bloom et al Host galaxy

E. Pian – LNGS, 13 Sep 2005 GRB050509b (z = 0.22) Upper limits on optical Flux are inconsistent With supernova Hjorth et al. 2005

E. Pian – LNGS, 13 Sep 2005 t -4 ν -1 GRB looks long to BAT (T 90 =153s), but would be short to BATSE (<1s) GRB (z = 0.257)

E. Pian – LNGS, 13 Sep 2005 Optical afterglow of the short GRB (T = 0.25 s) Berger et al. 2005

E. Pian – LNGS, 13 Sep 2005 Host Galaxy of the Short GRB (z = 0.257) Bloom et al SFR < 0.03 Msun/yr

E. Pian – LNGS, 13 Sep 2005 Isotropic irradiated –ray energy vs redshift GRB/SN Short GRB GRB z = 6.29

E. Pian – LNGS, 13 Sep 2005 SNe/GRB: the X-ray light curves Initial X-ray flux is Very different: afterglow-like emission in GRB-SNe? Kouveliotou et al Pian et al. 2004

E. Pian – LNGS, 13 Sep 2005 X-ray properties of Core Collapse SNe Compare to predictions of standard (1foe) jet model for different orientations SNe follow the trend, but a universal jet cannot explain all SNe Pian et al., in prep.

E. Pian – LNGS, 13 Sep 2005 X-ray properties of Core Collapse SNe With normalisation GRB/SNe angles agree with results from optical spectra SN2003dh jet was stronger ? SN2002ap jet was very weak ? Alt: Differences in jet or in ISM properties?

E. Pian – LNGS, 13 Sep 2005

Properties of GRB/HNe: Photospheric velocities Velocity also seems to be proportional to global properties: GRB/SNe have the highest velocities

E. Pian – LNGS, 13 Sep 2005 Conclusions The nebular spectrum of the Type Ic energetic SN2003jd is different from that of SN1998bw: it exhibits a double-peaked [O I] emission line, which suggests an aspherical geometry and an equatorial view. This is consistent with the lack of a detected GRB, and could support a unified scenario for SNe and GRBs Are hypernovae the most aspherical SNe? Possibly, and this would be related to the presence of GRBs In this picture, X-ray flashes may be off-axis GRBs or weaker explosions Short GRBs have afterglows similar to those of long GRBs. They are Preferentially detected at lower redshifts, and in galaxies with scarce Star formation. The evidence that they are not associated with supernovae is increasing. They are probably double neutron star mergers Are hypernovae the only aspherical SNe Ic? No, normal Ic are polarized Optical flashes probe the early emission mechanisms and circumburst medium