1 SN-GRB Connection: Observations and Questions Massimo Della Valle INAF-Osservatorio Astrofisico di Arcetri, Firenze Bologna, 1 Giugno, 2006

2 Outline Introduction

3 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB

4 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc)

5 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc) SNe-Ibc & Hypernova & GRBs rates

6 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc) SNe-Ibc & Hypernova & GRBs rates Time lag SN-GRBs

7 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc) SNe-Ibc & Hypernova & GRBs rates Time lag SN-GRBs GRB hosts

8 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc) SNe-Ibc & Hypernova & GRBs rates Time lag SN-GRBs GRB hosts Discussion & Conclusions

9 Outline Introduction SN 1998bw/GRB , SN 2003dh/GRB , SN 2003lw/GRB Bumps (SN 2002lt & SN 2005nc) SNe-Ibc & Hypernova & GRBs rates Time lag SN-GRBs GRB hosts Discussion & Conclusions Recent (exciting) Results

10 Gamma-ray bursts: prompt emission “Brief (< 100 sec) and intense (~10 -6 erg/cm 2 /s) flashes of soft (~100 keV) gamma-ray radiation” Temporal beahviour: wide variety Highly structuredSingle pulse  t << T

11 Long and short GRBs GRBs duration: (0.01 ÷ 100) s The distribution is bimodal Hardness/duration correlation: short bursts are harder All the results I will present concern the long-duration class of GRBs! Paciesas et al. 2000

12 Afterglows Long-lived counterparts at X-ray, optical, IR and radio wavelengths Discovery: GRB by the BeppoSAX satellite Optical counterparts soon after Costa et al van Paradijs et al. 1999

13 Jakobsson et al. 2005

14 Clues about progenitors The distance is ~ a few Gpc  3.1  cm Observed flux 10  5/-6 erg cm  2 s  1  luminosity : erg

15 Energetic Scale: Jets or Sphere GRB has been detected by the robotic telescope ROTSE, 22s and 47s after the  -ray trigger at V~11.7 and 8.9, respectively. At z=1.6, the isotropic energy release implies M V ~-35 and a global energetic budget comparable to >M  c 2 All GRBs could be collimated events, with opening angles  ~ 5-10 degrees (break in the power law decay of the afterglows, polarization)

16 And in fact the jet effect on the light curve was observed in several GRBs. Here is an example. Due to its nature the jet break time measured from the observations (i.e. monitoring) of the burst afterglow allows to estimate the physical aperture of the GRB jet. “Jet break” Jet break time t break Jet opening angle

17 “True” energetics: correcting the energyes derived with the assumption that GRBs are isotropic the energy crisis is relaxed. Moreover the typical energetics clusters around a similar value of 10^51 erg which is by far more standard also in comparison to other astro sources. Frail et al Isotropic equivalent energy E true = E iso (1 – cos )

18 X-ray Flashes

19 Probable Sequence of GRB Events The central engine emits a large amount of energy. Most of that energy accelerates a small mass (~10 -5 M  ) to speeds > 99.99% of lightspeed (  ~100/500) Collisions between different shells of ejected debris creates the gamma rays. Collisions between ejected debris and interstellar gas create the afterglow.

20 The progenitors collapses or coalesceces, forming a spinning BH Progenitor location:<10 8 cm …and the colliding shells give rise to the GRB GRB location <10 14 cm The energy escapes in the form of jets… observer Afterglow location <10 18 cm Kinetic Energy Shock dissipation Afterglow Dense cloud

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22 SNe & GRBs Facts ‘Early Gamma-Rays from Supernovae’ (Colgate 1968 & 1974) GRB  SN 1998bw (Galama et al. 1998)

23 SN 1998bw was discovered on NTT images of ESO 184 G82 at z= The GRB and the SN appeared spatially (P~10 -4/-5 ) and temporally coincident  t= +0.7d -2.0d (Iwamoto et al. 1998) SN 1998bw rivals with SN 1991T: M B =-19.5 To achieve such a luminosity about M  of Ni have to be synthesized in the explosion. This is unprecedented for Core Collapse events (less than 0.1 M  ) The radio emitting shell was expanding at (mildly) relativistic velocities  ~1.8 (Kulkarni et al. 1998; Weiler et al. 1999)

24 Patat et al. 2001

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26 Patat et al Mg I O I [Ca II] [O I] Na I Ca II

27 Patat et al. 2001

28 Pec Type Ic SNe Broad lines  Large Kinetic Energy  “Hypernovae” (only SN1998bw was associated with a GRB) Narrow lines  “normal” KE (10 51 )  Normal SN Ic

29 Pec Type Ic SNe = Hypernovae Broad lines  Large Kinetic Energy  “Hypernovae” (only SN1998bw was associated with a GRB) Narrow lines  “normal” KE (10 51 )  Normal SN Ic

30 Light Curves of Supernovae & Hypernovae Brightness alone should not be used to define a hypernova, whose main characteristic is the high E k ~10 52 ergs (see broad spectral feautures)

31 SN 1998bw = SN 1987A E ~ 30×10 51 ergsE ~ 1×10 51 ergs

32 Circumstantial evidence: The Bumps (Bloom et al. 1999) Della Valle et al Della Valle et al (MISTICI Collaboration)

33 Are the bumps representative of signatures of incipient SNe? Or they can be produced by different phenomena as dust echoes or thermal re- emission of the afterglow or thermal radiation from a pre-existing SN remnant (e.g. Esin & Blandfors 2000; Waxman & Draine 2000; Dermer 2003)

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50 Ca SUPERNOVA 2002lt The spectrum of the afterglow associated with GRB , obtained during the bump, reveals the presence of a broad absorption feature (FWHM~150 A), blueshifted by ~15000 km/s, which has been identified with CaII H+K  SUPERNOVA 2002lt Della Valle et al. 2003

51 SN 1994I

52 SN 1998bw was a peculiar Ic associated with a peculiar GRB  energy budget about a few x ergs) Evidence for the existence of a SN/GRB connection was circumstantial before March 2003 SN bumps were only suggestive for the existence of a SN/GRB connection. The spectroscopic confirmation was obtained only in one case (SN 2002lt/GRB ) and based on one spectrum (z=1). In addition the lightcurve was different from SN 1998bw

53 The Smoking Gun (part 1) 2003dh /GRB

54 GRB /SN 2003dh = Smoking Gun I Stanek et al.2003; Hjorth et al Apr Spectrum - 1 Apr Spectrum = ?

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56 Matheson et al z=0.16

57 The spectrum is very similar to the one exhibited by the type Ic SN 1998bw GRB and SN events are spatial coincident and coeval SN 2003dh was not so bright as 1998bw ( M  56 Ni) Modelling (Deng et al. 2005): M ej ~ 7±3M  ; Prog = M  ; M BH ~ 3 M  Fe II lines broader than [O I] (Maeda et al. 2005, 2006)  aspherical explosion The  -energy associated with GRB is ‘’standard’’ (6.9 x erg ) Sakamoto et al GRB /SN 2003dh: facts

58 GRB & SN 2003lw Malesani et al The Smoking Gun (part 2)

59 GRB /2003lw = Smoking Gun II Trigger from INTEGRAL Observations: ESO NTT & VLT Afterglow: X-ray (XMM) & radio (VLA) Low redshift host galaxy (z = 0.1) Very faint: E  erg Götz et al Watson et al. 2004, Soderberg et al. 2004

60 Spectroscopic Observations VLT + FORS Bright star-forming host galaxy SFR  10 M  /yr Z  0.1Z  A V  1.1 Prochaska et al Chincarini et al Broad undulations in the continuum close to the maximum Malesani et al. 2004

61 Spectra of SN 2003lw Host galaxy subtracted Tagliaferri et al Malesani et al E K = 6 x erg M 56 Ni = 0.55 M  M ej = 13 M  M prg = M  Mazzali et al. 2006

62 The very bright supernova 2003lw SN 2003lw vs SN 1998bw With E(B–V) = 1.1: *0.5 mag brighter *Same colors *Slower evolution Overall similar See also Bersier et al. 2004; Thomsen et al. 2004, Cobb et al. 2004, Gal-Yam et al Malesani et al. 2004

63 Conclusions The discovery of the types Ic SNe 2003dh (Stanek et al. 2003; Hjorth et al. 2003) and SN 2003lw (Malesani et al. 2004) in the AGs of GRB and GRB has conclusively linked long duration GRBs with the death of massive stars  Particularly with a subclass of SNe-Ibc, the bright tail of HYPs Is the game over?

64 …there is an expanding frontier of ignorance… (R. Feynman, Six Easy Pieces) Not at all...

65 There is growing evidence that GRBs can be associated with SNe which are different from SN 1998bw, both in the peak of luminosity and in spectroscopic type (SN 2002lt/GRB  SN 1994 I normal Ibc 1994I) What SN types are connected with GRBs? (only 1998bw-like?)

66 SN in XRF LC Fits: a normal SN Ic or a low-E Hyp like SN2002ap at z~0.6 Fynbo et al. 2004; Tominaga et al.2004 Lg (Fx/F  ) > 0 XRF >-0.5 XRR <-0.5 GRB GRB021211/SN 2002lt

67 Levan et al. 2005

68 Garnavich et al GRB IIn ?

69 Soderberg et al. 2005

70 Soderberg et al. 2005

71 Soderberg et al XRF  fainter than 2002ap/SN 1994I by 3-6 mag (i.e. M V ~ -13/-15)

72 1. It is not clear whether or not only Hypernovae are capable to produce GRBs or also “standard” Ib/c events can do it (IIn??) 2. The distributions of the absolute mag at max of GRB/SNe and standard Ibc are statistically indistinguishable  effect of scanty statistic? they derive from the same SN population? (very heterogeneous class of objects) All GRB-SNe which have received a spectroscopic confirmation belong to the bright tail of Ibc distribution  observational bias ?

73 What is the fraction of SNe-Ib/c which produces GRBs ? Rate for Ib/c: 0.22 SNu (Cappellaro et al. 1999) 1.2 x 10 8 L B,  Mpc -3 (Madau, Della Valle & Panagia 1998)  2.6 x 10 4 SNe-Ibc Gpc -3 yr -1 HYPs/Ibc ? (No absolute rate from controlled time surveys) 5-10% Podsiadlowski et al. 2004, Della Valle 2005

74 Rates of GRBs Local rate: GRB Gpc -3 yr -1 (Schmidt 2001, Guetta et al. 2004) Gpc -3 yr -1 (Firmani et al. 2004) 0.01 Gpc -3 yr -1 (Matsubayashi et al. 2005) 2.6x10 4 SNe-Ibc Gpc -3 yr -1 ~500 (Frail et al. 2001) ~75 (Guetta, Piran & Waxman 2004) GRB/Hyp: 25%-4% GRB/SNe-Ibc: 2%-0.3% GRB/Hyp ~ 0.1, IF ~ 200 GRB/Hyp ~ 1, IF ~ 2000 GRB+XRR+XRF /SNe-Ibc ~ 1, IF ~30000 Soderberg, Nakar & Kulkarni 2005 Radio survey on 74 Ibc+ Optical Rau et al Podsiadlowski et al GRB/Hyp ~1 < 1200

75 Radio light curves of HNe Soderberg et al.2006 Only GRB-SNe show strong radio emission. No-GRB-HNe, like 2002ap, do not. Either no jets or low-density environments. The presence of relativistic jets is the mark between GRB/XRF-HNe and ordinary SNe/HNe

76 Discussion and Conclusions

77 1.Long duration GRBs are closely connected with the death of massive stars. Spectroscopic observations have been carried out over a large range of redshifts (z= bw; z= aj z= lw; z= dh; z=0.23 XRF ; z=0.6 GRB a and possibly up to z~1, 2002lt).

78 2. Only a very small fraction of all massive stars appears capable to produce GRBs. SNe- Ib/c are the natural candidates because of the lack of H envelope. However, this does not seem to be sufficient: only ~ 1% of SNe-Ibc (~10% of Hyps) produce GRBs.  Some special circumstances are requested to the GRB star progenitor besides being “only” a massive star (Rotation, e.g. Woosley & Hegel 2006, Binarity, e.g. Podsiadlowski et al. 2004; Mirabel et al. 2003, Asymmetry Maeda et al ). This point is not well understood (yet).

79 3. The unification scheme where every SNe-Ibc is producing a GRB, XRR or XRF according to different viewed angles (e.g. Lamb et al. 2005), is not favored by current estimates of SN/GRB rates and radio observations. Unification works for ~ ( ~ 0 o.5 ) HYP & GRB Rates give ~ 200 ( ~ 6 o ) Radio Obs SNe-Ibc give 2 o.5)

80 Recent Results GRB A/SN 2005cn (Della Valle et al. 2006) GRB060218/SN 2006aj (Campana et al. 2006)

81 GRB a: a new SN connection Discovered by Swift solid = keV dots = keV short dashed = keV long dashed = keV Blustin et al z=0.606 Della Valle et al E(B-V)=0.1 Blustin et al. 2005

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83 Follow-up at TNG, NTT and VLT+FORS2 Della Valle et al. 2006

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89 Hyp with short rising time  on axis event (Maeda et al. 2006)

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94 Host galaxy of XRF060218/SN2006aj (DSS2) z = M v (host) = -16 Host has brightness Similar to SMC Z/Z  ~ 0.3 Associated with SN 2006aj (Masetti et al. 2006)

95 Steep decline common Gets shallower around here Examples of Swift-XRT light curves Nousek et al. 2005

96 Campana et al …in any type of SN triggered by core collapse, a shock is generated which propagates through the progenitor star and ejects the envelope. Accompanying the emergence of the shock wave through the surface of the star is a very bright UV/X burst of radiation… (A. Burrows 1992) …the internal energy following an adiabatic expansion of the envelope leads to a luminosity peak at 1 day and 1% of the observed luminosity… (Colgate & White 1964)

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99 We have observed for the first time in a GRB a thermal component which we have interpreted as signature of the shock break-out (Colgate 60s) We have caught a SN in the act of exploding (about 100s after the collapse of the core) We have definitely proved that SN and GRB are coeval events

100 Summary of SN-GRB time lag GRBSN +t+t-t-t Ref bw Iwamoto et al Bump Lazzati et al ke0-5 Bloom et al. + Garnavich et al lt Della Valle et al dh Kawabata et al Matheson lw 0-2 Malesani et al Bump 2 0 Stanek et al A2005nc 2 0 Della Valle et al.

101 Observations of SNe and bumps connected with GRBs imply that SNe and gamma bursts are simultaneous events. This favors the collapsar model (Woosley 1993, Paczynski 1998, MacFadyen & Woosley 1999) over competing theories (e.g. Supranova, Vietri & Stella 1998)

102 We have observed for the first time in a GRB a thermal component which we have interpreted as signature of the shock break-out (Colgate 60s) We have caught a SN in the act of exploding (about 100s after the collapse of the core) We have definitely proved that SN and GRB are coeval events We have measured the radius of the progenitor star, to be about 4 x cm which is typical of a W-R star.

103 Red Supergiant R~3x10 13 cm Blue Supergiant R~4x10 12 cm Wolf-Rayet Star R~4x10 11 cm SNe C-C (II, Ib, Ic) 

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105 The properties of the 4 closest SNe associated with GRBs vary by at most 30%. The  -budget covers about 4 order of magnitudes.

106 a) we may be seeing intrinsically similar phenomena under different angles. GRB /SN 2003dh may be viewed ~  pole-on, GRB /SN 1998bw considerably off-axis (15-30°, Maeda et al ). GRB /SN 2003lw may lie in between (Ramirez-Ruiz et al. 2005) In this scenario the  -properties are a strong function of the angle (E     whereas the optical properties are not much influenced by this relative small spread in viewing angles. b) GRB /SN 2006aj  there is an intrinsic dispersion in the properties of the relativistic ejecta for SNe with similar optical characteristics.  relativistic energies at play in (local) GRB phenomenon (~ erg) are small compared to the KE involved in the “standard” SN-Ibc (10 51 erg) or Hyp (10 52 erg) explosions.

107 HL-GRBs vs. LL-GRBs HL-GRBs (  -ray budget of erg ~ SN/HN KE) LL-GRBs (intrinsically faint erg ~ 10 -4/-2 SN KE) Sampled volume smaller  Rate LL-GRBs: x HL-GRBs rate (Della Valle 2006, Pian et al. 2006, Soderberg et al. 2006, Liang et al. 2006) LL-GRBs vs HL-GRBs  properties of SN explosions??  Different properties in the central engine (=compact stellar remnant NS vs BH)? Lack of t break implies   (cfr. 5 o -10 o ) GRBs occur in star forming and low metallicity galaxies. If they are sensitive to metallicity, we can expect systematic differences between nearby and cosmological GRBs (the latter produced in low-metallicity environments). e.g. GRB at z=6.3 (Kawai et al. 2005, Tagliaferri et al. 2005) is quite atypical (duration energy content, variability). Nomoto et al aj