The Exceptional GRB/XRF and its Associated SN 2006aj Jinsong Deng National Astronomical Observatories of China

Why is it Exceptional? extremely long duration T 90 ~ 2100 sec (typical GRB ~ 10 – 100 sec) dominated by soft X-ray photons E peak ~ 5 keV  X-ray Flash (typical GRB > 100 keV) under-luminous E iso ~ 6 x erg (typical GRB > erg) a UV LC bump peaking at ~ 30,000 sec associated with SN 2006aj the 1st clear XRF-SN connection

SWIFT Prompt BAT/XRT/UVOT Obs. Campana et al. Nature 06 Aug 31

Swift Long-term XRT / UVOT LCs Campana et al. Nature 06 Aug 31 SN 2006aj ?

A Low-redshift Drawf Host Galaxy z ~ the 2nd closet GRB drawf (fainter than SMC) M(B) ~ -16  ~ 0.01 L *, ~ 10 8 M ⊙ SRF ~ 0.05 M ⊙ yr -1 Mirabal et al. 06 GCN Pian et al. Nature 06 Aug 31 Sollerman et al. 06 A&A Modjaz et al. 06 ApJL Mirabal et al. 06 ApJL SDSS-2 pre-burst

The Emergence of SN 2006aj “A Heavenly Gift for the KITP GRB06 Program” –– Alicia Soderberg 2006 No H/He lines  type Ic earliest spectra for any Ibc Masetti et al. VLT Feb 21.05UT, Soderberg et al. Gemini Feb 21.02UT Fugazza et al. TNG Feb 20.93UT, Mirabal et al. MDM Feb 20.10UT, etc

Models of  -ray and X-ray Obs. a thermal X-ray comp.+ UV LC bump Campana et al. Nature 06  “Shock break-out” of dense WR wind ? Liang et al. 06: double themal comps. Butler 06: no thermal comp., but Fe emi. lines Li 06: requiring progenitor > 80 R ⊙ too large for WR Ghisellini et al. 06: UV/opt SED consistent with non- thermal X-ray comp., but not the thermal one Fan et al. 06: non-thermal comp due to central engine thermal comp due to jet-cocoon Models for prompt  -ray emi. Dai et al. 06: inverse-Compton scattering of “shock break-out”thermal photons Wang et al. 06: bulk-Compton scattering of “shock break-out” themal photons

VLT SN Spectra and LCs Pian al Nature submitted Pian et al. Nature 06 Aug 31

NAOC SN LCs and Spectra photometry: 80cm TNT spectroscopy: 2.16m consistent with VLT but of low S/N Deng et al. 06 in prep.

Spec. Comp. with Other Ibc SNe Mazzali, Deng et al Nature submitted Mazzali, Deng et al. Nature 06 Aug 31

LC Comp. with Other Ibc SNe Mazzali, Deng et al Nature submitted Pian et al. Nature 06 Aug 31

Modeling the VLT Spectra much less M & KE than other GRB-SNe M ~ 2 M ⊙, KE ~ 2 x erg SNe 1998bw, 2003dh, 2003lw ~ 8 – 13 M ⊙, ~ 30 – 70 x erg  hypernovae Mazzali, Deng et al. Nature 06 Aug 31

V ph Comp. With other Ibc SNe

Modelling the LC Mazzali, Deng et al Nature submitted using the same model as for spectra M ~ 2 M ⊙, KE ~ 2 x erg M( 56 Ni) ~ 0.2 M ⊙ Mazzali, Deng et al. Nature 06 Aug 31

Modelling the Nebular Spectrum obtained on Jul 26 with Keck by Foley et al. our modelling is going on M ~ 2 M ⊙, M( 56 Ni) ~ 0.2 M ⊙ M(O) ~ 1.4 M ⊙

KE ~ M MS of SNe and HNe NS BH

M( 56 Ni) ~ M MS of SNe and HNe NS BH

Radio Comp. with Other Ibc SNe Soderberg al in prep x less luminous than x less luminous than early turn-on  on-axis mildly- elativistic (  ) material Soderberg et al. Nature 06 Aug 31

Amati E p ~ E iso Correlation a Amati 06 MNRAS, Amati et al. 06 E p ~ E iso 0.5 XRFs , , a & GRB outliers: GRBs ,

Different Origins of GRBs and XRFs GRB-connected SNe display heterogeneity SN 98bw-like (large M, large KE) M MS ~ M ⊙  BH formation  collapsar   large  in relativistic jets  GRB SN 06aj-like (low M, low KE) M MS ~ 20 M ⊙  NS formation  ms magnetar activity   small  in relativistic jets  XRF newborn ms magnetar B > 3 x G, P ~ 1 ms  L dipole > erg s -1 Usov 92 Nature, Thompson 94 MNRAS, Nakamura 98 P. Theo. Phys., Wheeler 00 ApJ

Local Sub-luminous GRBs in all the 7 GRBs with z<0.2, at least 5 are sub-luminous GRB z E iso (erg) SN connction E48 X-ray rich SN 1998bw E49 XRF SN 2006aj B E (?) 1.2E49 SN excluded !? E50 X-ray rich SN 2003lw (?) 8.9E50 SN excluded !? E52 X-ray rich SN 2003dh E49 XRF possible SN over-population of local sub-luminous GRBs a rate hundrends times that of cosmological GRBs the Sino-French GRB mission Eclair/SVOM will do better in exploring this population than Swift Pian et al. 06 Nature, Soderberg et al. 06 Nature 06, Liang et al. 06, Cobb et al. 06 ApJL