Large-scale Evolution of Seconds-long Relativistic Jets from Black Hole–Neutron Star Mergers

Creators: Gottlieb, Ore¹; Issa, Danat¹; Jacquemin-Ide, Jonatan¹; Liska, Matthew²; Foucart, Francois³; Tchekhovskoy, Alexander¹; Metzger, Brian D.^{4, 5}; Quataert, Eliot⁶; Perna, Rosalba^{5, 7}; Kasen, Daniel^{8, 9}; Duez, Matthew D.¹⁰; Kidder, Lawrence E.¹¹; Pfeiffer, Harald P.¹²; Scheel, Mark A.¹³

1. Northwestern University
2. Harvard University
3. University of New Hampshire
4. Columbia University
5. Center for Computational Astrophysics, Flatiron Institute, New York, NY 10010, USA
6. Princeton University
7. Stony Brook University
8. University of California, Berkeley
9. Lawrence Berkeley National Laboratory
10. Washington State University
11. Cornell University
12. Max Planck Institute for Gravitational Physics
13. California Institute of Technology

Abstract

We present the first numerical simulations that track the evolution of a black hole–neutron star (BH–NS) merger from premerger to r ≳ 10¹¹ cm. The disk that forms after a merger of mass ratio q = 2 ejects massive disk winds (3–5 × 10⁻² M ⊙). We introduce various postmerger magnetic configurations and find that initial poloidal fields lead to jet launching shortly after the merger. The jet maintains a constant power due to the constancy of the large-scale BH magnetic flux until the disk becomes magnetically arrested (MAD), where the jet power falls off as L_j ∼ t⁻². All jets inevitably exhibit either excessive luminosity due to rapid MAD activation when the accretion rate is high or excessive duration due to delayed MAD activation compared to typical short gamma-ray bursts (sGRBs). This provides a natural explanation for long sGRBs such as GRB 211211A but also raises a fundamental challenge to our understanding of jet formation in binary mergers. One possible implication is the necessity of higher binary mass ratios or moderate BH spins to launch typical sGRB jets. For postmerger disks with a toroidal magnetic field, dynamo processes delay jet launching such that the jets break out of the disk winds after several seconds. We show for the first time that sGRB jets with initial magnetization σ 0 > 100 retain significant magnetization (σ ≫ 1) at r > 10¹⁰ cm, emphasizing the importance of magnetic processes in the prompt emission. The jet–wind interaction leads to a power-law angular energy distribution by inflating an energetic cocoon whose emission is studied in a companion paper.

Copyright and License

Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

O.G. is supported by a CIERA Postdoctoral Fellowship. O.G. and A.T. acknowledge support by Fermi Cycle 14 Guest Investigator program 80NSSC22K0031. D.I. is supported by Future Investigators in NASA Earth and Space Science and Technology (FINESST) award No. 80NSSC21K1851. J.J. and A.T. acknowledge support by NSF grants AST-2009884 and NASA 80NSSC21K1746. A.T. and F.F. acknowledge support from NSF grant AST-2107839 and NASA grant 80NSSC18K0565. A.T. was also supported by NSF grants AST-1815304, AST-1911080, AST-2206471, and OAC-2031997. A.T. was also partly supported by NSF-BSF grant 2020747. F.F. also acknowledges support from the Department of Energy, Office of Science, Office of Nuclear Physics, under contract No. DE-AC02-05CH11231 and NASA through grant 80NSSC22K0719. R.P. acknowledges support by NSF award AST-2006839. M.D. acknowledges support from PHY-2110287. Support for this work was also provided by the National Aeronautics and Space Administration through Chandra award No. TM1-22005X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. This research used resources of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility supported under contract DE-AC05-00OR22725. This research was facilitated by the Multimessenger Plasma Physics Center (MPPC), NSF grant PHY-2206607. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract No. DE-AC02-05CH11231 using NERSC award NP-ERCAP0020543 (allocation m2401). An award of computer time was provided by the ASCR Leadership Computing Challenge (ALCC), Innovative and Novel Computational Impact on Theory and Experiment (INCITE), and OLCF Director's Discretionary Allocation programs under award PHY129. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under contract No. DE-AC02-05CH11231 using NERSC award ALCC-ERCAP0022634.

Files

Gottlieb_2023_ApJL_954_L21.pdf

Files (11.9 MB)

Name	Size	Download all
Gottlieb_2023_ApJL_954_L21.pdf md5:837d54773b8f2fa0d7e8091322589c17	11.9 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes