Published January 1, 2022 | Version v1
Journal article Open

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

  • 1. Istanbul Univ, Grad Sch Sci, Dept Astron & Space Sci, TR-34119 Istanbul, Turkey
  • 2. Sabanci Univ, Fac Engn & Nat Sci, TR-34956 Istanbul, Turkey
  • 3. Indian Inst Technol Indore, Dept Astron Astrophys & Space Engn DAASE, Khandwa Rd, Indore 453552, India
  • 4. Georgia Inst Technol, Sch Phys, Ctr Relativist Astrophys, 837 State St, Atlanta, GA 30332 USA
  • 5. CALTECH, Cahill Ctr Astron & Astrophys, Pasadena, CA 91125 USA
  • 6. Univ Space Res Assoc, Sci & Technol Inst, 320 Sparkman Dr, Huntsville, AL 35805 USA
  • 7. Tech Univ Denmark, Natl Space Inst, Elektrovej 327-328, DK-2800 Lyngby, Denmark
  • 8. UPS OMP, CNES, CNRS, Inst Rech Astrophys & Planetol, 9 Ave Colonel Roche,BP 44346, F-31028 Toulouse 4, France
  • 9. MIT, Kavli Inst Astrophys & Space Res, 77 Massachusetts Ave, Cambridge, MA 02139 USA

Description

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.

Files

bib-8ea6396f-ac12-4f3d-9ca2-88a53d5ac4a3.txt

Files (281 Bytes)

Name Size Download all
md5:cce2dd22344dc97c92739647a8d75a39
281 Bytes Preview Download