Revealing the Spectral State Transition of the Clocked Burster, GS 1826-238, with NuSTAR StrayCats

Creators: Yun, S. B.; Grefenstette, B. W.; Ludlam, R. M.; Brumback, M. C.; Buisson, D. J. K.; Mastroserio, G.; Pike, S. N.

Abstract

We present the long-term analysis of GS 1826-238, a neutron star X-ray binary known as the Clocked Burster, using data from NuSTAR StrayCats. StrayCats, a catalog of NuSTAR stray light data, contains data from bright, off-axis X-ray sources that have not been focused by the NuSTAR optics. We obtained stray light observations of the source from 2014–2021, reduced and analyzed the data using nustar-gen-utils Python tools, demonstrating the transition of the source from the island atoll state to a banana branch. We also present the light-curve analysis of Type I X-ray bursts from the Clocked Burster and show that the bursts from the banana/soft state are systematically shorter in duration than those from the island/hard state and have a higher burst fluence. From our analysis, we note an increase in the mass accretion rate of the source, and a decrease in burst frequency with the transition.

Additional Information

© 2023. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. This work was supported by the National Aeronautics and Space Administration (NASA) under grant number 80NSSC19K1023 issued through the NNH18ZDA001N Astrophysics Data Analysis Program (ADAP). This research was performed at the California Institute of Technology (Caltech) under the Summer Undergraduate Research Fellowship (SURF) program. Additionally, this work made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software and Calibration teams for their support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This research has made use of data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC.

Attached Files

Published - Yun_2023_ApJ_947_81.pdf

Files

Yun_2023_ApJ_947_81.pdf

Files (2.3 MB)

Name	Size	Download all
Yun_2023_ApJ_947_81.pdf md5:6cfbb1191a74590db223cdf22bb96463	2.3 MB	Preview Download

Additional details

	All versions	This version
Views	0	0
Downloads	0	0
Data volume	0 Bytes	0 Bytes