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Title: Broadband Spectral Investigations of Magnetar Bursts

Abstract

We present our broadband (2–250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550−5418, SGR 1900+14, and SGR 1806−20 detected with the Rossi X-ray Timing Explorer ( RXTE ) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship ismore » a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.« less

Authors:
; ; ;  [1]
  1. Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı Tuzla, Istanbul 34956 (Turkey)
Publication Date:
OSTI Identifier:
22661091
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal, Supplement Series; Journal Volume: 232; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CATALOGS; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; EMISSION SPECTRA; GAMMA RADIATION; HARDNESS; INDEXES; KEV RANGE; MAGNETIC STARS; NEUTRON STARS; PULSARS; X RADIATION

Citation Formats

Kırmızıbayrak, Demet, Şaşmaz Muş, Sinem, Kaneko, Yuki, and Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu. Broadband Spectral Investigations of Magnetar Bursts. United States: N. p., 2017. Web. doi:10.3847/1538-4365/AA88B7.
Kırmızıbayrak, Demet, Şaşmaz Muş, Sinem, Kaneko, Yuki, & Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu. Broadband Spectral Investigations of Magnetar Bursts. United States. doi:10.3847/1538-4365/AA88B7.
Kırmızıbayrak, Demet, Şaşmaz Muş, Sinem, Kaneko, Yuki, and Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu. Fri . "Broadband Spectral Investigations of Magnetar Bursts". United States. doi:10.3847/1538-4365/AA88B7.
@article{osti_22661091,
title = {Broadband Spectral Investigations of Magnetar Bursts},
author = {Kırmızıbayrak, Demet and Şaşmaz Muş, Sinem and Kaneko, Yuki and Göğüş, Ersin, E-mail: demetk@sabanciuniv.edu},
abstractNote = {We present our broadband (2–250 keV) time-averaged spectral analysis of 388 bursts from SGR J1550−5418, SGR 1900+14, and SGR 1806−20 detected with the Rossi X-ray Timing Explorer ( RXTE ) here and as a database in a companion web-catalog. We find that two blackbody functions (BB+BB), the sum of two modified blackbody functions (LB+LB), the sum of a blackbody function and a power-law function (BB+PO), and a power law with a high-energy exponential cutoff (COMPT) all provide acceptable fits at similar levels. We performed numerical simulations to constrain the best fitting model for each burst spectrum and found that 67.6% of burst spectra with well-constrained parameters are better described by the Comptonized model. We also found that 64.7% of these burst spectra are better described with the LB+LB model, which is employed in the spectral analysis of a soft gamma repeater (SGR) for the first time here, than with the BB+BB and BB+PO models. We found a significant positive lower bound trend on photon index, suggesting a decreasing upper bound on hardness, with respect to total flux and fluence. We compare this result with bursts observed from SGR and AXP (anomalous X-ray pulsar) sources and suggest that the relationship is a distinctive characteristic between the two. We confirm a significant anticorrelation between burst emission area and blackbody temperature, and find that it varies between the hot and cool blackbody temperatures differently than previously discussed. We expand on the interpretation of our results in the framework of a strongly magnetized neutron star.},
doi = {10.3847/1538-4365/AA88B7},
journal = {Astrophysical Journal, Supplement Series},
number = 1,
volume = 232,
place = {United States},
year = {Fri Sep 01 00:00:00 EDT 2017},
month = {Fri Sep 01 00:00:00 EDT 2017}
}