X-Ray Burst and Persistent Emission Properties of the Magnetar SGR 1830-0645 in Outburst
Journal article, 2022

We report on NICER X-ray monitoring of the magnetar SGR 1830-0645 covering 223 days following its 2020 October outburst, as well as Chandra and radio observations. We present the most accurate spin ephemerides of the source so far: nu = 0.096008680(2) Hz, <(nu) over dot> = -6.2(1) x 10(-14) Hz s(-1), and significant second and third frequency derivative terms indicative of nonnegligible timing noise. The phase-averaged 0.8-7 keV spectrum is well fit with a double-blackbody (BB) model throughout the campaign. The BB temperatures remain constant at 0.46 and 1.2 keV. The areas and flux of each component decreased by a factor of 6, initially through a steep decay trend lasting about 46 days, followed by a shallow long-term one. The pulse shape in the same energy range is initially complex, exhibiting three distinct peaks, yet with clear continuous evolution throughout the outburst toward a simpler, single-pulse shape. The rms pulsed fraction is high and increases from about 40% to 50%. We find no dependence of pulse shape or fraction on energy. These results suggest that multiple hot spots, possibly possessing temperature gradients, emerged at outburst onset and shrank as the outburst decayed. We detect 84 faint bursts with NICER, having a strong preference for occurring close to the surface emission pulse maximum-the first time this phenomenon is detected in such a large burst sample. This likely implies a very low altitude for the burst emission region and a triggering mechanism connected to the surface active zone. Finally, our radio observations at several epochs and multiple frequencies reveal no evidence of pulsed or burst-like radio emission.

Author

George Younes

George Washington University

Chin-Ping Hu

National Changhua University of Education

Karishma Bansal

California Institute of Technology (Caltech)

Paul S. Ray

Naval Research Laboratory

Aaron B. Pearlman

McGill University

California Institute of Technology (Caltech)

Franz Kirsten

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics

Zorawar Wadiasingh

NASA Goddard Space Flight Center

University of Maryland

Ersin Gogus

Sabanc─▒ University

Matthew G. Baring

Rice University

Teruaki Enoto

RIKEN

Zaven Arzoumanian

NASA Goddard Space Flight Center

Keith C. Gendreau

NASA Goddard Space Flight Center

Chryssa Kouveliotou

George Washington University

Tolga Guver

Istanbul University

Alice K. Harding

Los Alamos National Laboratory

Walid A. Majid

California Institute of Technology (Caltech)

Harsha Blumer

West Virginia University

Jason W. T. Hessels

University of Amsterdam

Netherlands Institute for Radio Astronomy (ASTRON)

Marcin P. Gawronski

Nicolaus Copernicus University

Vladislavs Bezrukovs

Ventspils University of Applied Sciences

Arturs Orbidans

Ventspils University of Applied Sciences

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 924 2 136

Subject Categories

Meteorology and Atmospheric Sciences

Astronomy, Astrophysics and Cosmology

Atom and Molecular Physics and Optics

DOI

10.3847/1538-4357/ac3756

More information

Latest update

2/3/2022 1