A Subclass of GRBs as


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• A Subclass of GRBs as
• Possible LIGO2 GravitationalWave Sources
• Jay P. Norris
• NASA/GSFC
• 1 The prevalent belief structure
• Some All? GRBs associated with SNe.
• 2 Demographics attributes of possible subclass
  of nearby ultralow luminosity GRBs and their
  associates nearby type Ib/c SNe.
• 3 Predicted range of GW strains detection rate
  for GRB subclass

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• GRBSN Belief Sparse Knowledge Structure
• One very close ? 35 Mpc ultralow luminosity
  GRB and one not so close ? 680 Mpc subluminous
  GRB
• Both manifest the presence of Type 1c SNe.
• Constrained but open issue The delay in some
  cases
• ?TSNTGRB?simultaneous?
• Detection of GW signal could depend on accurate
  knowledge of TSN or TGRB. Accurate TGRB is easy.
• GW signal requires nonaxisymmetric deformation
  ? Theoretical core collapses ? 104102
  to unity.
• Is degree of nonaxisymmetry related to GRB jet
  opening angle via BH rotation?

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Figure 2. The detailed classification of SNe
requires not only the identification of specific
features in the early spectra but also the
analysis of the line profiles luminosity and
spectral evolutions. Cappellero Turrato
astroph/0012455
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E. Pian astroph/9910236 Revised BeppoSAX error
box for GRB 980425
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22 days
Iwamoto et al. 1998 Modeling yields core
collapse for SN1998bw within 0.7/2 days of GRB
980425
12 days
40 days
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Young Baron Branch 1995
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GRB 011211 z 2.14 Reeves et al.
Nature 2001 416
Blueshifted Xray lines ? ? 0.09 assume ?jet
? 20º ne 1015 cm3 ? GRB ejecta runs into SN
shell at R 1015 cm ? TGRB TSN 4 days
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• Are there T0_SN ? T0_GRB delays?
• SN 1998bw light curve has evidence for upturn
  end of UV breakout ? which would place T0_SN
  few days before T0_GRB. Modeling ?T 20.7
  days
• Xray afterglow spectral analysis GRB 011211
  suggests 4day hiatus SN to GRB.
• Type 1c SNe light curves not well studied and
  are known to vary in width by at least a factor
  of 3
• Cannot gauge T0_SN accurately by comparison with
  SN 1998bw especially given GRB afterglow
  photometry at faint magnitudes.
• [Theory ?T 10s hrs Woosley et al.
  collapsars
• ?T ??? van Putten BHtorus ]

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• Corecollapse SN Explode Asymmetrically
• Images of 1987A see ST Jan 2002 Wang
  Wheeler
• Elemental asymmetries in Wang et al.
  2002
• SN remnants 1987A Cas A
• Polarization in SNe Wang et al.
  2001
• Type 1a
• Type II 12 increasing with time
• Type 1b/c 37
• GRB observed by RHESSI Coburn Boggs
  Nature
• Some GRBs beamed into 4?/[500/2] Frail et al.
  2002
• SN Modeling strong polar ejections
• Pulsar space velocities
• ? Some SNe are rapidly rotating at corecollapse
  high T/W.
• Nonaxisymmetric bar instabilities
  possible ?

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• A SubPopulation of Nearby GRBs ?
• BATSE subsample 7 of softspectrum GRBs.
  Defining characteristic Very long pulses with
  long spectral lags 0.3 s.
• Proportion increases to 50 near BATSE
  threshold.
• Additional Evidence for Nearby Spatial
  Distribution
• GRB980425/SN1998bw is canonical example at 38
  Mpc.
• Log NLog Fp has 3/2 slope cosmology
  unimportant.
• Tendency towards Supergalactic Plane similar to
  SN Ib/c longlag GRB and nearby galaxy sky
  distributions similar.
• Implications Detected sample d Ultralow luminosity RGRB ¼ RSN Ib/c
• Could be LIGO II sources 4 yr1 within
  50 Mpc
• see ApJ
  2002 579 386

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Typical longlag GRB detected by BATSE.
300 keV blue 100300 keV green 50
100 keV yellow 25 50 keV red
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HETE2 time profile for GRB 030329 5120 keV
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A Main Sequence HR Diagram for GammaRay
Bursts L53 1.1 ? ?lag/0.01 s1.15
Woosley MacFadyen 1999 Ioka Nakamura
2001 others predicted subclass of numerous
nearby GRBs low luminosity softspectrum
longlag. Properties attributed to 1 large jet
opening angle 2 low ? 25.
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M. J. Hudson 1993
7200 km/s 100 Mpc z 0.024
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980425
971208
Virgo
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SNe Ib/Ic 62 detected 19542001.75
2/3 since 1998.0 With 85 at distances 100 Mpc. Only 10 of nearby SNe are detected.
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RGRB
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Fryer Holz Hughes 2002 Blondin Mezzacappa
DeMarino 2003 Bar instabilities
likely ? unity. Assuming 100 cycles
f 200800 Hz source 1.3 ? 1023 Expect 4 longlag GRBs yr1 50 Mpc and we know when they occur.
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• Summary
• Very good evidence that highmass highly
  energetic corecollapse SNe are associated with
  GRBs one nearby a few cosmologically distant
  examples of such associations.
• Evidence indicates that these SNe and GRB events
  are asymmetric ? high T/W. Are SN and GRB
  simultaneous?
• Longlag softspectrum apparently nearby ultra
  lowluminosity GRBs are numerous 50 near
  BATSE threshold.
• RGRB RSNIb/c.
• A few yr1 detectable by LIGO
  II.
• Swift should see a larger fraction of longlag
  GRBs than BATSE.
• ? Many chances to find the associated SNe and GW
  signals

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The End
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G.M. Harry et al.
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Lmin
?vmax
L const. across jet
?vmin
Lmax
?jet
?jet varies ?view varies
?view varies 2?20?. outside jet
cone. inside profiled jet.
Beaming Fraction Viewing angle
Profiled jet ?4? Ld? constant Special
Relativity L? reflects ?? ? ?? ? L1.
Lorentz contraction 30 Doppler boost
jet fastest on axis All three models realize
broad observed but narrow actual Luminosity and
Energy distributions.
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GRBs Lpeak vs. ?
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CCF Lag
Time
GRBs Lpeak vs. ?
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• Possible Confirmation Approaches
• 1 Untriggered BATSE bursts For Fp cm2 s1 longlag bursts predominate. But
  larger localization errors IDing as bona fide
  GRBs is problematic.
• 2 400500 additional triggered BATSE bursts.
• 3 Crosscorrelation of nearby matter
  distribution
• d
• 4 Extrapolation of SNe light curves to T0
  comparison with GRB times and positions J.
  Bonnell.
• 5 Swift