Implications of the Lag-Luminosity Relationship for Unified Gamma-Ray Burst Paradigms

By Jay Norris. 2002

180 citations recorded by the source corpus.

Spectral lags (τlag) are deduced using a cross-correlation methodology for 1429 long (T90 > 2 s) BATSE gamma-ray bursts (GRBs) with peak flux Fp > 0.25 photons cm-2 s-1, near to the BATSE trigger threshold. The lags are modeled as a power-law function of peak flux with limit parameters for the lag extrema. Lag model errors are assigned via a novel decimation procedure, drawing from the observed lag distribution with Fp and τlag as governing parameters. The model parameters were adjusted within a five-dimensional grid to achieve best agreement with the observed distribution in the Fp-τlag plane. Assuming a two-branch lag-luminosity relationship, the lags are self-consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations and for unified gamma-ray/afterglow scenarios that would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor. A component of the burst sample is identified—those with few, wide pulses, lags of a few tenths to several seconds, and soft spectra—whose log N- log Fp distribution approximates a -3/2 power law, suggesting homogeneity and relatively nearby sources. The proportion of long-lag bursts increases from negligible among bright BATSE bursts to ~50% at trigger threshold. Bursts with very long lags, ~1-2 s < τlag < 10 s, show a tendency to concentrate near the supergalactic plane with a quadrupole moment of roughly -0.10 ± 0.04. GRB 980425 (SN 1998bw) is a member of this subsample of ~90 bursts with estimated distances less than 100 Mpc. The frequency of the observed ultralow-luminosity bursts is ~ that of Type Ib/c supernovae (SNe Ib/c) within the same volume. The model lags predict a power-law scaling relation for the ultralow-luminosity GRBs, dNsen/dL ~ L-1, flatter than expected (dNsen/dL ~ L1/6) if viewing angle with respect to the jet axis alone governed perceived luminosity. For high-luminosity bursts, the modeling yields dNvol/dL ~ L-1.8, similar to expectations for viewing angle scenarios (dNvol/dL ~ L-2); however, if luminosity decreases off-axis, L ~ θ (λ > 0), then overproduction of low-luminosity bursts results. Thus, the relativistic kinematic factor as the dominant component for the dynamic range in GRB luminosities is not favored. The variable beaming fraction scenario, with constant luminosity across the jet cone, can fit the high-luminosity bursts with a fairly flat distribution in jet cone solid angle, dN(Ωjet)/dΩjet ∝ Ω; for the ultralow-luminosity bursts a distribution that increases is required, dN(Ωjet)/dΩjet ∝ Ω. Jets with variable luminosity profiles viewed at a range of angles can also reproduce the observed luminosity distributions, such that L ~ θ and L ~ θ for high- and ultralow-luminosity regimes, respectively. Approximately 1/300 of the universal SN Ib/c population would be required to produce GRBs at cosmological distances, with a rate of 1 × 106 to a few times 106 yr-1. The modeled redshift distribution for GRBs peaks at z ~ 10, with large uncertainty.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

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In Astronomy and Astrophysics

1. Bing Zhang
2. Pawan Kumar
3. E. Berger
4. E. Liang
5. B. Metzger
6. D. Burrows
7. Binbin Zhang
8. N. Gehrels

In Instrumentation

1. Bing Zhang
2. E. Liang
3. Pawan Kumar
4. J. Bonnell
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6. Z. Dai
7. D. Burrows
8. E. Berger

In Nuclear and High Energy Physics

1. Bing Zhang
2. Pawan Kumar
3. E. Berger
4. E. Liang
5. J. Bonnell
6. D. Frail
7. Shrinivas R. Kulkarni
8. Z. Dai

Citations in the corpus

• A Cosmology-Independent Calibration of Gamma-Ray Burst Luminosity Relations and the Hubble Diagram (2008, background): “However, in the case of GRBs, the observed long-GRB rate falls off rapidly at low redshifts, and some nearby GRBs may be intrinsically different (e.g., GRB 980425, GRB 031203; Norris 2002; Soderberg et al. 2004; Guetta et al. 2004; Liang & Zhang 2006a).”
• An Analysis of Gamma-Ray Burst Spectral Break Models (2002, background): “On the other hand, GRB light-curve variabilities (Fenimore & Ramirez-Ruiz 2000; Reichart et al. 2001) and spectral lags (Norris et al. 2000; Norris 2002) have been proposed as Cepheid-like luminosity indicators for the long duration (tb>∼2 s) GRBs.”
• Gamma-Ray Burst Formation Rate Inferred from the Spectral Peak Energy-Peak Luminosity Relation (2003, background): “These properties might be due to the effect of the viewing angle to the GRB jet (e.g., Ioka & Nakamura 2001; Norris 2002; Murakami et al. 2003).”
• Low-Luminosity Gamma-Ray Bursts as a Unique Population: Luminosity Function, Local Rate, and Beaming Factor (2006, methodology): “Some authors have attempted to determine the lumi- nosity function (Φ) and the local rate (ρ0) of long GRBs through fitting the logN − logP or V/Vmax distributions observed by CGRO/BATSE (Schmidt 2001; Stern et al. 2002; Lloyd-Ronning et al. 2002; Norris 2002; Guetta et al. 2005) or through simulati”
• Short Gamma-Ray Bursts with Extended Emission (2006, methodology): “It remains to explain the negligible spectral lags that are characteristic of short bursts at energies above ~ 15 keV, in contrast to the signature of positive lags in long bursts (Norris 2002).”
• Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst Prompt Emissions and X-Ray Flares with Swift Data (2006, background): “…studies have been made of the curvature effect in the prompt emission phase (Fen- – 4 – imore et al. 1996; Sari & Piran 1997; Ryde & Petrosian 2002; Norris 2002; Kocevski et al. 2003; Qin et al. 2004; Shen et al. 2005; Qin & Lu 2005), no conclusive evidence supporting this effect has been…”
• The physics of gamma-ray bursts & relativistic jets (2014, background): “• A “spectral lag”, namely, pulses with a lower energy being systematically lagged behind those with a high energy, is observed in the keV - MeV regime for many long GRBs (Norris et al., 2000; Norris, 2002; Norris et al., 2005).”
• The sub-energetic γ-ray burst GRB 031203 as a cosmic analogue to the nearby GRB 980425 (2004, background): “We expect intensive follow-up of faint bursts with smooth γ-ray light curve”
• Long-Lag, Wide-Pulse Gamma-Ray Bursts (2005, methodology): “3 of Norris 2002).”
• The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts (2006, background): “Norris (2002) demonstrated that the long lag bursts (hence the lowest luminosity and generally the closest) show a concentration to the supergalactic plane.”
• Quantum-gravity analysis of gamma-ray bursts using wavelets (2002, methodology): “Increasing numbers of redshifts have been measured in recent years, and the spectral time lags of GRB light curves have been investigated in a number of papers (Norris et al. 1994; Band 1997; Norris et al. 2000; Ellis et al. 2000b; Norris 2002).”
• Gamma-Ray Bursts in the Swift Era (2007, background): “If one however assumes a standard radiation unit in the comoving frame, this relation may be simply related to a varying Doppler-boosting parameter among bursts (Salmonson 2000; Ioka & Nakamura 2001; Norris 2002).”
• Gamma-Ray Burst Energetics and the Gamma-Ray Burst Hubble Diagram: Promises and Limitations (2003, methodology): “Recently, Schaefer (2003) presented another GRB Hubble diagram based on bursts that have two empirical distance indicators: the variability index (Fenimore & Ramirez-Ruiz 2000; Norris, Marani, & Bonnell 2000; Reichart et al. 2001) and the lag-luminosity correlation (Norris 2002).”