A Subclass of GRBs as Possible LIGO-2 Gravitational-Wave 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, ultra-low luminosity GRBs and their associates, nearby type Ib/c SNe. (3) Predicted range of GW strains, detection rate for GRB subclass

 GRB  SN 1998bw  GRB  SN 2003dh Only 20% of observed GRBs have associated redshifts: Some fraction of the remaining 80% may lie at higher redshifts. Obs’d SN z max =1.77

GRB-SN Belief Sparse Knowledge Structure:  One very close (  35 Mpc) ultra-low 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)  T SN –T GRB  <~ few days. Are the events simultaneous? Detection of GW signal could depend on accurate knowledge of T SN or T GRB. Accurate T GRB is easy.  GW signal requires non-axisymmetric deformation (  ); Theoretical core collapses:  ~ to “unity”. Is degree of non-axisymmetry related to GRB jet opening angle (via BH rotation)?

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: astro- ph/ )

E. Pian astro-ph/ Revised BeppoSAX error box for GRB

Iwamoto et al. (1998): Modeling yields core collapse for SN1998bw within +0.7/  2 days of GRB days 40 days 12 days

Young, Baron & Branch (1995)

GRB , z = 2.14 Reeves et al., Nature, 2001, 416 Blue-shifted X-ray lines (   0.09); assume:  jet  20º, n e ~ cm -3  GRB ejecta runs into SN shell at R ~ cm  T GRB - T SN ~ 4 days

Matheson et al., GCN 2120; Stanek et al. (astro-ph/ )

Are there T 0_SN  T 0_GRB delays? SN 1998bw light curve has evidence for upturn (end of “UV breakout” ?), which would place T 0_SN ~ few days before T 0_GRB. Modeling:  T = -2,+0.7 days X-ray afterglow spectral analysis (GRB ) suggests 4-day 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 T 0_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, BH-torus ]

Core-collapse SN Explode Asymmetrically:  Images of 1987A (see S&T, 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: <~ 0.3%  Type II: ~ 1-2%, increasing with time  Type 1b/c: ~ 3-7% {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 core-collapse, high T/W. Non-axisymmetric (bar) instabilities possible,  <~ unity.

A Sub-Population of “Nearby” GRBs ? BATSE subsample (~ 7%) of soft-spectrum 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 N—Log F p has ~ -3/2 slope: cosmology unimportant. Tendency towards Supergalactic Plane, similar to SN Ib/c; long-lag GRB and nearby galaxy sky distributions similar. Implications: Detected sample, d <~ 100 Mpc. Ultra-low luminosity (<~ ergs s -1 ). Rate: R GRB ~ ¼ R SN Ib/c *** Could be LIGO II sources: ~ 4 yr -1 within 50 Mpc *** (see ApJ 2002, 579, 386)

> 300 keV: blue keV: green keV: yellow keV: red “Typical” long-lag GRB, detected by BATSE.

HETE-2 time profile for GRB , keV

A Main Sequence “HR Diagram for Gamma-Ray Bursts” L 53 ≈ 1.1  (  lag /0.01 s) Prediction: Woosley & MacFadyen (1999), Ioka & Nakamura (2001), others predicted subclass of numerous, nearby GRBs: low luminosity, soft-spectrum, long-lag. Properties attributed to: (1) large jet opening angle & (2) low  ~ 2-5.

M. J. Hudson (1993) 7200 km/s 100 Mpc z = 0.024

Virgo

SNe Ib/Ic : 62 detected , (> 2/3 since ) With 85% at distances < 100 Mpc. Only ~10% of “nearby” SNe are detected.

R GRB (< 100 Mpc) ~ 30 yr -1 ~ ¼ R SNIb/c

Fryer, Holz & Hughes (2002); Blondin, Mezzacappa & DeMarino (2003) : Bar instabilities likely (  ~ unity). Assuming 100 cycles, f ~ Hz, source < 50 Mpc  h/  Hz ~ 1.3  Expect ~ 4 long-lag GRBs yr -1 (< 50 Mpc), and we know when they occur. 50 Mpc 680 Mpc

Summary  Very good evidence that high-mass, highly energetic core-collapse 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?  Long-lag, soft-spectrum, apparently nearby, ultra low-luminosity GRBs are numerous (~ 50%) near BATSE threshold. R GRB (<100 Mpc) ~ 30/yr ~ ¼ R SNIb/c. A few yr -1 detectable by LIGO II.  Swift should see a larger fraction of “long-lag” GRBs than BATSE.  Many chances to find the associated SNe and GW signals !!!

The End

G.M. Harry et al.

 jet varies,  view varies,  view varies, ~ 2  –20 . outside jet cone. inside profiled jet. L min L max Beaming Fraction Viewing angle Profiled jet  4  Ld  ~ constant, Special Relativity: L(  ) reflects  (  ):    L -1. Lorentz contraction 30 <  (  ) < 1000 & Doppler boost (jet fastest on axis) All three models realize broad observed, but narrow actual Luminosity and Energy distributions.  v,max  v,min  jet L ~ const. across jet

GRBs : L peak vs. 

CCF Lag Time

Possible Confirmation Approaches (1) Untriggered BATSE bursts: For F p < 0.25 ph cm -2 s -1 long-lag bursts predominate. But, larger localization errors; ID’ing as bona fide GRBs is problematic. (2) ~ additional triggered BATSE bursts. (3) Cross-correlation of nearby matter distribution (d < 100 Mpc) and GRB positions (M. Hudson). (4) Extrapolation of SNe light curves to T 0, comparison with GRB times and positions (J. Bonnell). (5) Swift