CaltechAUTHORS
Published August 1, 2022 | Version public
Journal Article Metadata-only

Burst-Disk Interaction in 4U 1636-536 as Observed by NICER

Creators

  • 1. ROR icon Istanbul University
  • 2. ROR icon Sabancı University
  • 3. ROR icon University of Maryland, College Park
  • 4. ROR icon Indian Institute of Technology Indore
  • 5. ROR icon Georgia Institute of Technology
  • 6. ROR icon California Institute of Technology
  • 7. ROR icon Universities Space Research Association
  • 8. ROR icon Technical University of Denmark
  • 9. ROR icon Goddard Space Flight Center
  • 10. ROR icon Research Institute in Astrophysics and Planetology
  • 11. ROR icon Massachusetts Institute of Technology

Abstract

We present the detection of 51 thermonuclear X-ray bursts observed from 4U 1636–536 by the Neutron Star Interior Composition Explorer (NICER) over the course of a 3 yr monitoring campaign. We perform time-resolved spectroscopy for 40 of these bursts and show the existence of a strong soft excess in all the burst spectra. The excess emission can be characterized by the use of a scaling factor (the f_a method) to the persistent emission of the source, which is attributed to the increased mass accretion rate onto the neutron star due to Poynting–Robertson drag. The soft excess emission can also be characterized by the use of a model taking into account the reflection of the burst emission off the accretion disk. We also present time-resolved spectral analysis of five X-ray bursts simultaneously observed by NICER and AstroSat, which confirm the main results with even greater precision. Finally, we present evidence for Compton cooling using seven X-ray bursts observed contemporaneously with NuSTAR, by means of a correlated decrease in the hard X-ray lightcurve of 4U 1636–536 as the bursts start.

Additional Information

We thank the referee for their very valuable and constructive comments. T.G. has been supported in part by the Scientific and Technological Research Council (TÜBİTAK), 119F082, and the Turkish Republic, Presidency of Strategy and Budget, project 2016K121370. This work was supported by NASA through the NICER mission and the Astrophysics Explorers Program. P.B. acknowledges support from the CRESST II cooperative agreement (80GSFC21M0002). R.M.L. acknowledges the support of NASA through Hubble Fellowship Program grant HST-HF2-51440.001. S.G. acknowledges the support of the CNES. This research has made use of software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. This paper includes data publicly available from the AstroSat mission of the Indian Space Research Organisation (ISRO), archived at the Indian Space Science Data Centre (ISSDC). M.C. acknowledges support from ISRO under the AstroSat archival data utilization program (DS 2B-13013(2)/4/2020-Sec.2). Facility: NICER, AstroSat, NuSTAR - . Software: HEASoft, XSPEC, Sherpa, CIAO, Astropy.

Additional details

Identifiers

Eprint ID
116657
Resolver ID
CaltechAUTHORS:20220908-184431283

Funding

TUBITAK
119F082
Turkish Strategy and Budget Presidency
2016K121370
CRESST II
80GSFC21M0002
Hubble Fellowship Program
HST-HF2-51440.001
NASA
NICER mission
Astrophysics Explorers Program
CNES (France)
High Energy Astrophysics Science Archive Research Center (HEASARC)
Indian Space Research Organisation (ISRO)
AstroSat archival data utilization program (DS 2B-13013(2)/4/2020-Sec.2)

Dates

Created
2022-09-07
Created from EPrint's datestamp field
Updated
2022-09-08
Created from EPrint's last_modified field