Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

Nikhil Sarin; Paul D. Lasky; Gregory Ashton

doi:10.1093/MNRAS/STAA3090

Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

Nikhil Sarin, Paul D. Lasky, Gregory Ashton

School of Physics and Astronomy

Research output: Contribution to journal › Article › Research › peer-review

17 Citations (Scopus)

Abstract

The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as n = 4.85⁺₋⁰₀¹¹₁₅ suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

Original language	English
Pages (from-to)	5986-5992
Number of pages	7
Journal	Monthly Notices of the Royal Astronomical Society
Volume	499
Issue number	4
DOIs	https://doi.org/10.1093/MNRAS/STAA3090
Publication status	Published - 2020

Keywords

Gamma-ray burst: general – gamma-ray bursts

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10.1093/MNRAS/STAA3090

Cite this

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title = "Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars",

abstract = "The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as n = 4.85+−001115 suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.",

keywords = "Gamma-ray burst: general – gamma-ray bursts",

author = "Nikhil Sarin and Lasky, {Paul D.} and Gregory Ashton",

note = "Funding Information: CE170100004. PDL and GA are supported by ARC Discovery Project DP180103155. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Funding Information: We thank the anonymous referee for their comments. We are grateful to Antonia Rowlinson and Guilia Stratta for helpful discussions. This research was supported by an Australian Government Research Training Program (RTP) Scholarship. PDL is supported through Australian Research Council Future Fellowship FT160100112 and Publisher Copyright: 2020 The Author(s)",

year = "2020",

doi = "10.1093/MNRAS/STAA3090",

language = "English",

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pages = "5986--5992",

journal = "Monthly Notices of the Royal Astronomical Society",

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AU - Sarin, Nikhil

AU - Lasky, Paul D.

AU - Ashton, Gregory

N1 - Funding Information: CE170100004. PDL and GA are supported by ARC Discovery Project DP180103155. This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester. Funding Information: We thank the anonymous referee for their comments. We are grateful to Antonia Rowlinson and Guilia Stratta for helpful discussions. This research was supported by an Australian Government Research Training Program (RTP) Scholarship. PDL is supported through Australian Research Council Future Fellowship FT160100112 and Publisher Copyright: 2020 The Author(s)

PY - 2020

Y1 - 2020

N2 - The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as n = 4.85+−001115 suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

AB - The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations of a significant fraction of short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with the spin-down of a magnetar central engine through an arbitrary braking index. Combining this with a model for the tail of the prompt emission, we show that our model can better explain the data than millisecond-magnetar models without radiative losses or those that invoke spin-down solely through vacuum dipole radiation. We find that our model predicts a subset of X-ray flares seen in some gamma-ray bursts. We can further explain the diversity of X-ray plateaus by altering the radiative efficiency and measure the braking index of newly born millisecond magnetars. We measure the braking index of GRB061121 as n = 4.85+−001115 suggesting the millisecond-magnetar born in this gamma-ray burst spins down predominantly through gravitational-wave emission.

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Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

Abstract

Keywords

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Putting Einstein to the Test: Probing Gravity with Gravitational Waves

Extreme astrophysics in the age of gravitational waves

ARC Centre of Excellence for Gravitational Wave Discovery

Cite this

Interpreting the X-ray afterglows of gamma-ray bursts with radiative losses and millisecond magnetars

Abstract

Keywords

Access to Document

Other files and links

Projects

Putting Einstein to the Test: Probing Gravity with Gravitational Waves

Extreme astrophysics in the age of gravitational waves

ARC Centre of Excellence for Gravitational Wave Discovery

Cite this