Prompt Periodicity in the GRB 211211A Precursor: Black-hole or magnetar engine?
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| Format: | Preprint |
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2025
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| author | Lamb, Gavin P. Baxter, Thomas Omand, Conor M. B. Dimple McGrath, Zoë Turnbull, Cairns Burns, Eric Hamidani, Hamid Mandel, Ilya Page, Kim L. Rosswog, Stephan Sarin, Nikhil Blain, Andrew Datrier, Laurence Kobayashi, Shiho Levan, Andrew Starling, Rhaana Gompertz, Benjamin Habeeb, Nusrin Nguyen, Khang Tanvir, Nial |
| author_facet | Lamb, Gavin P. Baxter, Thomas Omand, Conor M. B. Dimple McGrath, Zoë Turnbull, Cairns Burns, Eric Hamidani, Hamid Mandel, Ilya Page, Kim L. Rosswog, Stephan Sarin, Nikhil Blain, Andrew Datrier, Laurence Kobayashi, Shiho Levan, Andrew Starling, Rhaana Gompertz, Benjamin Habeeb, Nusrin Nguyen, Khang Tanvir, Nial |
| contents | The merger origin long GRB 211211A was a class (re-)defining event. A precursor was identified with a $\sim 1$ s separation from the main burst, as well as a claimed candidate quasi-periodic oscillation (QPO) with a frequency $\sim20$ Hz. Here, we explore the implications of the precursor, assuming the quasi-periodicity is real. The precursor variability timescale requires relativistic motion with a Lorentz factor $Γ\gtrsim80$, and implies an engine driven jetted outflow. The declining amplitude of the consecutive pulses requires an episodic engine with an `on/off' cycle consistent with the QPO. For a black-hole central engine, the QPO can have its origin in Lense-Thirring precession of the inner disk at $\sim6-9$ $r_g$ (gravitational radii) for a mass $M_\bullet\leq4.5$ $M_{\odot}$, and $\lesssim 7$ $r_g$ for $M_\bullet>4.5$ $M_{\odot}$ and dimensionless spin $χ\sim 0.3 - 0.9$. Alternatively, at a disk density of $\sim10^{8 - 12}$ g cm$^{-3}$, the required magnetic field strength for a QPO via magnetohydrodynamic effects will be on the order $B\sim10^{12 - 14}$ G. If the central engine is a short lived magnetar or hypermassive neutron star, then a low-frequency QPO can be produced via instabilities within the disk at a radius of $\sim20 - 70$ km, for a disk density $\sim10^{9 - 12}$ g cm$^{-3}$ and magnetic field $\gtrsim10^{13 - 14}$ G. The QPO cannot be coupled to the neutron star spin, as the co-rotation radius is beyond the scale of the disk. Neither engine can be ruled out -- however, we favour an origin for the precursor candidate QPO as early jet-disk coupling for a neutron star -- black hole merger remnant with mass $M_\bullet>4.5$ $M_{\odot}$. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2503_15613 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Prompt Periodicity in the GRB 211211A Precursor: Black-hole or magnetar engine? Lamb, Gavin P. Baxter, Thomas Omand, Conor M. B. Dimple McGrath, Zoë Turnbull, Cairns Burns, Eric Hamidani, Hamid Mandel, Ilya Page, Kim L. Rosswog, Stephan Sarin, Nikhil Blain, Andrew Datrier, Laurence Kobayashi, Shiho Levan, Andrew Starling, Rhaana Gompertz, Benjamin Habeeb, Nusrin Nguyen, Khang Tanvir, Nial High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology The merger origin long GRB 211211A was a class (re-)defining event. A precursor was identified with a $\sim 1$ s separation from the main burst, as well as a claimed candidate quasi-periodic oscillation (QPO) with a frequency $\sim20$ Hz. Here, we explore the implications of the precursor, assuming the quasi-periodicity is real. The precursor variability timescale requires relativistic motion with a Lorentz factor $Γ\gtrsim80$, and implies an engine driven jetted outflow. The declining amplitude of the consecutive pulses requires an episodic engine with an `on/off' cycle consistent with the QPO. For a black-hole central engine, the QPO can have its origin in Lense-Thirring precession of the inner disk at $\sim6-9$ $r_g$ (gravitational radii) for a mass $M_\bullet\leq4.5$ $M_{\odot}$, and $\lesssim 7$ $r_g$ for $M_\bullet>4.5$ $M_{\odot}$ and dimensionless spin $χ\sim 0.3 - 0.9$. Alternatively, at a disk density of $\sim10^{8 - 12}$ g cm$^{-3}$, the required magnetic field strength for a QPO via magnetohydrodynamic effects will be on the order $B\sim10^{12 - 14}$ G. If the central engine is a short lived magnetar or hypermassive neutron star, then a low-frequency QPO can be produced via instabilities within the disk at a radius of $\sim20 - 70$ km, for a disk density $\sim10^{9 - 12}$ g cm$^{-3}$ and magnetic field $\gtrsim10^{13 - 14}$ G. The QPO cannot be coupled to the neutron star spin, as the co-rotation radius is beyond the scale of the disk. Neither engine can be ruled out -- however, we favour an origin for the precursor candidate QPO as early jet-disk coupling for a neutron star -- black hole merger remnant with mass $M_\bullet>4.5$ $M_{\odot}$. |
| title | Prompt Periodicity in the GRB 211211A Precursor: Black-hole or magnetar engine? |
| topic | High Energy Astrophysical Phenomena General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2503.15613 |