Quasi-periodic Oscillations in GRB 210514A: a Case of a Newborn Supra-Massive Precessing Magnetar Collapsing into a Black Hole?
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arXiv
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| Format: | Preprint |
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2024
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| _version_ | 1866929456223879168 |
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| author | Zou, Le Cheng, Ji-Gui |
| author_facet | Zou, Le Cheng, Ji-Gui |
| contents | Magnetar is proposed as one of the possible central engines for a gamma-ray burst (GRB). Recent studies show that if a magnetar has a rotational axis misaligned from the magnetic one, a periodic lightcurve pattern is expected with a period of seconds to minutes. Inspired by this unique feature, in this paper, we search for the quasi-periodic oscillation (QPO) signals in the {\it Swift} observations of GRBs. Using the Lomb-Scargle periodogram and the weighted wavelet Z-transform algorithms, we find that the {\it Swift}-BAT data of GRB 210514A has a QPO signal with a period $\sim 11\,{\rm s}$. The estimated confidence level of the signal is over $3 σ$. The global lightcurve of this GRB exhibits a double-plateau structure with a sharp decay segment between plateaus. The lightcurve feature resembles those of GRBs that were reported to have internal plateaus. We explain the observations of GRB 210514A with a supra-massive magnetar (SMM) model, where the QPO signal in the first plateau is produced via the dipole radiation of the SMM experiencing a precession motion, the sharp decay is due to the collapse of the SMM into a black hole (BH), and the second plateau could be produced via the fall-back accretion of the newborn BH. We fit the precession model to the observations using the Bayesian statistic and the best-fit magnetar parameters are discussed. Alternative models concerning a BH central engine may also provide reasonable explanations for this burst, only in this case the QPO signal could merely be a coincidence. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_06225 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Quasi-periodic Oscillations in GRB 210514A: a Case of a Newborn Supra-Massive Precessing Magnetar Collapsing into a Black Hole? Zou, Le Cheng, Ji-Gui High Energy Astrophysical Phenomena Magnetar is proposed as one of the possible central engines for a gamma-ray burst (GRB). Recent studies show that if a magnetar has a rotational axis misaligned from the magnetic one, a periodic lightcurve pattern is expected with a period of seconds to minutes. Inspired by this unique feature, in this paper, we search for the quasi-periodic oscillation (QPO) signals in the {\it Swift} observations of GRBs. Using the Lomb-Scargle periodogram and the weighted wavelet Z-transform algorithms, we find that the {\it Swift}-BAT data of GRB 210514A has a QPO signal with a period $\sim 11\,{\rm s}$. The estimated confidence level of the signal is over $3 σ$. The global lightcurve of this GRB exhibits a double-plateau structure with a sharp decay segment between plateaus. The lightcurve feature resembles those of GRBs that were reported to have internal plateaus. We explain the observations of GRB 210514A with a supra-massive magnetar (SMM) model, where the QPO signal in the first plateau is produced via the dipole radiation of the SMM experiencing a precession motion, the sharp decay is due to the collapse of the SMM into a black hole (BH), and the second plateau could be produced via the fall-back accretion of the newborn BH. We fit the precession model to the observations using the Bayesian statistic and the best-fit magnetar parameters are discussed. Alternative models concerning a BH central engine may also provide reasonable explanations for this burst, only in this case the QPO signal could merely be a coincidence. |
| title | Quasi-periodic Oscillations in GRB 210514A: a Case of a Newborn Supra-Massive Precessing Magnetar Collapsing into a Black Hole? |
| topic | High Energy Astrophysical Phenomena |
| url | https://arxiv.org/abs/2408.06225 |