Afterglow light curves, viewing angle and the jet structure of γ-ray bursts

By E. Rossi, D. Lazzati, M. Rees. 2001

351 citations recorded by the source corpus.

Gamma-ray bursts are often modelled as jet-like outflows directed towards the observer; the cone angle of the jet is then commonly inferred from the time at which there is a steepening in the power-law decay of the afterglow. We consider an alternative model in which the jet has a beam pattern where the luminosity per unit solid angle (and perhaps also the initial Lorentz factor) decreases smoothly away from the axis, rather than having a well-defined cone angle within which the flow is uniform. We show that the break in the afterglow light curve then occurs at a time that depends on the viewing angle. Instead of implying a range of intrinsically different jets – some very narrow, and others with a similar power spread over a wider cone – the data on afterglow breaks could be consistent with a standardized jet, viewed from different angles. We discuss the implication of this model for the luminosity function.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/0d2b959e8951d6eb2ca565391d3fce4457fbd20c

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Bing Zhang
2. B. Metzger
3. Pawan Kumar
4. E. Berger
5. E. Liang
6. Binbin Zhang
7. E. Nakar
8. T. Piran

In Nuclear and High Energy Physics

1. Bing Zhang
2. Pawan Kumar
3. B. Metzger
4. D. Giannios
5. E. Berger
6. J. McKinney
7. E. Liang
8. L. Sironi

Citations in the corpus

• The Propagation and Eruption of Relativistic Jets from the Stellar Progenitors of Gamma-Ray Bursts (2003, methodology): “Recent observations and afterglow modeling support this nonuniform jet model (Berger et al. 2003; Zhang et al. 2004; Salmonson 2003; Rossi et al. 2002).”
• Magnetic acceleration of ultrarelativistic jets in gamma-ray burst sources (2008, result): “…in phenomenological GRB jet models, which either take them to be uniform within the jet half-opening angle θj or else assume that the flow has a universal structure, with being a Gaussian or a power-law in θ (in particular, ∝ θ−2; Rossi et al. 2002 — compare with the bottom right panel of Fig.”
• DISCERNING THE PHYSICAL ORIGINS OF COSMOLOGICAL GAMMA-RAY BURSTS BASED ON MULTIPLE OBSERVATIONAL CRITERIA: THE CASES OF z = 6.7 GRB 080913, z = 8.2 GRB 090423, AND SOME SHORT/HARD GRBs (2009, background): “More complicated (maybe more realistic) jet models invoke distributions of jet energy with angle from the jet axis (Mészáros et al. 1998; Zhang & Mészáros 2002b; Rossi et al. 2002; Zhang et al. 2004).”
• THE MISSING LINK: MERGING NEUTRON STARS NATURALLY PRODUCE JET-LIKE STRUCTURES AND CAN POWER SHORT GAMMA-RAY BURSTS (2011, background): “Observers with lines of sight along these wings would then see a much dimmer and more typical SGRB (Rossi et al. 2002; Peng et al. 2005; Racusin et al. 2009); without such wings, however, the observations would suggest a very large intrinsic and beaming-corrected event rate per unit volume.”
• The physics of gamma-ray bursts & relativistic jets (2014, methodology): “Structured jets make it possible to understand the GRB phenomenology within the framework of a “quasi-universal” (Rossi et al., 2002; Zhang and Mészáros, 2002b; Zhang et al., 2004a) jet, i.e. GRB jets are similar to each other, and different observed properties are due to different viewing angles…”
• Gamma-Ray Burst Afterglows in the Multimessenger Era: Numerical Models and Closure Relations (2019, background): “Previous work has demonstrated that the light curves of structured jets show two modes of behavior, depending on whether the observer is aligned (q q<obs c) or misaligned (q q>obs c; Granot et al. 2002; Rossi et al. 2002; Panaitescu & Kumar 2003; van Eerten et al. 2010).”
• An Analysis of Gamma-Ray Burst Spectral Break Models (2002, methodology): “In the above Monte Carlo simulations, we have adopted a positive Γ ∝ Lk (k = 1/2 specifically) correlation, which is consistent with the expectation of the theoretical models (Kobayashi et al. 2002; Rossi et al. 2002; Zhang & Mészáros 2002; Salmonson & Galama 2002).”
• A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, background): “For an off-axis observer (Rossi et al., 2002; Zhang and Mészáros, 2002a), the lightcurve may show a jet-break-like feature as the jet axis enters the field of view, but the exact shape of the break depends on the angular structure of the jet and the viewing angle (Kumar and Granot, 2003; Granot an”
• Model-independent Multivariable Gamma-Ray Burst Luminosity Indicator and Its Possible Cosmological Implications (2005, background): “…2002), constant radiative efficiency (which also varies from burst to burst, e.g. Lloyd-Ronning & Zhang 2004; Bloom et al. 2003a and references therein), and the assumption of the top-hat jet configuration (in principle jets are possibly structured, Rossi et al. 2002; Zhang & Mészáros 2002b).”
• The evolution of the X-ray afterglow emission of GW 170817 / GRB 170817A in XMM-Newton observations (2018, background): “…with a fast and energetic inner core surrounded by a slower, less energetic layer/sheath/cocoon (first proposed for long GRBs – Lipunov et al. 2001; Rossi et al. 2002; Salafia et al. 2015 – and only recently extended to short GRBs – Kathirgamaraju et al. 2018; Lazzati et al. 2017a; Gottlieb et…”
• The Evolution of a Structured Relativistic Jet and Gamma-Ray Burst Afterglow Light Curves (2003, neutral): “Similar simplifications were made in the recent work on a universal structured jet (Rossi et al. 2002).”
• X-Ray-rich Gamma-Ray Bursts, Photospheres, and Variability (2002, background): “…the same data can be interpreted in terms of a nonuniform (angle dependent) cross section jet with a universal jet pattern given by the same functional relation between the energy output as a function of angle L ð Þ / 2 (Rossi et al. 2002; Zhang &Mészáros 2002; Salmonson & Galama 2002).”
• Gamma-ray burst afterglows (2006, methodology): “The relativistic ejecta are likely collimated (Rhoads 1999; Sari et al. 1999), and the jets may have substantial angular structures (Zhang & Mészáros 2002; Rossi et al. 2002).”