Time-dependent models of accretion discs formed from compact object mergers

By B. Metzger, A. Piro, E. Quataert. 2008

206 citations recorded by the source corpus.

We present time-dependent models of the remnant accretion discs created during compact object mergers, focusing on the energy available from accretion at late times and the composition of the disc and its outflows. We calculate the dynamics near the outer edge of the disc, which contains the majority of the disc's mass and determines the accretion rate on to the central black hole. This treatment allows us to follow the evolution over much longer time-scales (100s or longer) than current hydrodynamic simulations. At late times the disc becomes advective and its properties asymptote to self-similar solutions with an accretion rate M d ∞ t -4/3 (neglecting outflows). This late-time accretion can in principle provide sufficient energy to power the late-time activity observed by Swift from some short-duration gamma-ray bursts. However, because outflows during the advective phase unbind the majority of the remaining mass, it is difficult for the remnant disc alone to produce significant accretion power well beyond the onset of the advective phase. Unless the viscosity is quite low (α ≤ 10 -3 ), this occurs before the start of observed flaring at ∼30 s; continued mass inflow at late times thus appears required to explain the late-time activity from short-duration gamma-ray bursts. We show that the composition of the disc freezes-out when the disc is relatively neutron rich (electron fraction Y e ≃ 0.3). Roughly 10 -2 M ⊙ of this neutron-rich material is ejected by winds at late times. During earlier, neutrino-cooled phases of accretion, neutrino irradiation of the disc produces a wind with Y e ≃ 0.5, which synthesizes at most ∼10 -3 M ⊙ of 56 Ni. We highlight what conditions are favorable for 56 Ni production and predict, in the best cases, optical and infrared transients peaking ∼0.5-2d after the burst, with fluxes a factor of ∼10 below the current observational limits.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/834bfdfeb806a7593f68afcf4af20589f8342bcc

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In Astronomy and Astrophysics

1. B. Metzger
2. E. Berger
3. D. Kasen
4. R. Fern'andez
5. E. Quataert
6. Bing Zhang
7. Albino Perego
8. Luke F. Roberts

Citations in the corpus

• EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS (2013, background): “Though the physical properties of the disk winds remain uncertain, neutrino irradiation may drive the electron fraction to Ye & 0.4, in which case the nucleosynthesis may not extend past Z ∼ 50 (Surman et al. 2006, 2008; Metzger et al. 2008; Darbha et al. 2010).”
• Constraints on the neutron star equation of state from AT2017gfo using radiative transfer simulations (2018, background): “We find that only 10 per cent of the total amount of ejecta is dynamical ejecta, which supports the idea that the bulk of the ejecta comes from disc outflows (Metzger et al. 2008).”
• The long-term evolution of neutron star merger remnants – I. The impact of r-process nucleosynthesis (2013, background): “…after many viscous time-scales (∼ seconds) when viscous dissipation and the recombination of nucleons into light nuclei conspire to unbind a substantial fraction of whatever is left from the disc at that time (Lee & RamirezRuiz 2007; Beloborodov 2008; Metzger et al. 2008, 2009; Lee et al. 2009).”
• Red or blue? A potential kilonova imprint of the delay until black hole formation following a neutron star merger (2014, background): “This hierarchy is important because a large neutrino flux tends to drive Ye to a value higher than that in the disc midplane (e.g. Metzger et al. 2008a; Surman et al. 2008, 2014).”
• IDENTIFYING ELUSIVE ELECTROMAGNETIC COUNTERPARTS TO GRAVITATIONAL WAVE MERGERS: AN END-TO-END SIMULATION (2012, background): “A central premise of the model is that NS mergers produce ejecta from either dynamicallyejected tidal tails, or accretion disk outflows driven by early neutrino winds or late thermonuclear driven winds (e.g. Kulkarni 2005; Metzger et al. 2008, 2009; Dessart et al. 2009).”
• WHAT IS THE MOST PROMISING ELECTROMAGNETIC COUNTERPART OF A NEUTRON STAR BINARY MERGER? (2011, background): “Although the origin of this extended emission is still debated, one explanation is that it results from ongoing energy output from a highly magnetized neutron star, which survives the NS-NS merger (Metzger et al. 2008b; Bucciantini et al. 2011).”
• Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers (2017, background): “Finally, nuclear recombination assisted by viscous magnetic forces unbinds outer layers of the post-merger accretion disk and launches disk wind outflows (Chen & Beloborodov 2007; Metzger et al. 2008; Fernández & Metzger 2013; Just et al. 2015).”
• OPACITIES AND SPECTRA OF THE r-PROCESS EJECTA FROM NEUTRON STAR MERGERS (2013, background): “2) Following the merger, material which has accumulated in a centrifugally supported disk may be blown off in a neutrino or nuclear driven wind (Levinson 2006; Surman et al. 2006; Metzger et al. 2008, 2009).”
• Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers (2014, background): “…tori are known to evolve through three stages of radiation efficiency and correspondingly different mass-loss properties (cf. e.g., Beloborodov 2008; Metzger et al. 2008, 2009; Fernández & Metzger 2013): (1) high initial densities produce optically thick conditions for neutrinos so that neutrinos…”
• Gamma-Ray Bursts in the Swift Era (2009, background): “…(Houck and Chevalier 1991, Woosley 1993, MacFadyen and Woosley 1999, Narayan et al. 2001) and in binary mergers involving compact objects (Ruffert et al. 1997, Kluzniak and Lee 1998, Rosswog and Liebendörfer 2003, Lee et al. 2005b, Setiawan et al. 2006, Metzger et al. 2008, Rosswog et al. 2004).”
• GRB 080503: IMPLICATIONS OF A NAKED SHORT GAMMA-RAY BURST DOMINATED BY EXTENDED EMISSION (2008, methodology): “%) of the accretion disk that initially forms from the merger will also be ejected in powerful winds (Lee et al. 2005b) from the disk at late times; this material is also neutron rich and will produce radioactive isotopes (Metzger et al. 2008c).”
• The first direct double neutron star merger detection: Implications for cosmic nucleosynthesis (2017, background): “…al. 2016), neutrino-driven winds (Dessart et al. 2009; Perego et al. 2014) or the unbinding of accretion torus material (e.g. Lee & Ramirez-Ruiz 2007; Beloborodov 2008; Metzger et al. 2008; Fernandez & Metzger 2013; Just et al. 2015; Ciolfi & Siegel 2015; Martin et al. 2015; Siegel & Metzger 2017).”
• Neutrino-driven winds from neutron star merger remnants (2014, methodology): “…in an order-of-magnitude sense or via parametrized models (Ruffert et al. 1997; Rosswog & Ramirez-Ruiz 2002; Rosswog & Liebendörfer 2003; McLaughlin & Surman 2005; Surman, McLaughlin & Hix 2006; Metzger et al. 2008; Surman et al. 2008; Caballero, McLaughlin & Surman 2012; Wanajo & Janka 2012).”
• PS1-10jh: THE DISRUPTION OF A MAIN-SEQUENCE STAR OF NEAR-SOLAR COMPOSITION (2013, background): “…Kumar et al. 2008; Cannizzo & Gehrels 2009; Lopez-Camara et al. 2009; Milosavljević et al. 2012) and for a compact binary merger (Lee et al. 2004; Metzger et al. 2008; Lee et al. 2009; Metzger et al. 2009), it is likely not a perfect analogue for a tidal disruption of a star originally on a…”
• Electromagnetic counterparts of compact object mergers powered by the radioactive decay of r‐process nuclei (2010, background): “Although some of the wind-driven material in NS mergers may have high entropy (Surman et al. 2008; Metzger et al. 2008), most of the total mass ejected likely has low-modest entropy (S ∼ 3−10 kb baryon −1; Metzger et al. 2009a).”
• Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis (2018, background): “…on the long-term evolution of merger remnants also revealed the importance of the magnetically, neutrino-, and viscously driven secular outflows (Metzger et al. 2008, 2009, 2018; Dessart et al. 2009; Lee et al. 2009; Fernández & Metzger 2013; Metzger & Fernández 2014; Perego et al. 2014; Siegel…”