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Title: UNAMBIGUOUS DETECTION OF REFLECTION IN MAGNETIC CATACLYSMIC VARIABLES: JOINT NuSTAR–XMM-NEWTON OBSERVATIONS OF THREE INTERMEDIATE POLARS

In magnetic cataclysmic variables (CVs), X-ray emission regions are located close to the white dwarf surface, which is expected to reflect a significant fraction of intrinsic X-rays above 10 keV, producing a Compton reflection hump. However, up to now, a secure detection of this effect in magnetic CVs has largely proved elusive because of the limited sensitivity of non-imaging X-ray detectors. Here we report our analysis of joint NuSTAR–XMM-Newton observations of three magnetic CVs, V709 Cas, NY Lup, and V1223 Sgr. The improved hard X-ray sensitivity of the imaging NuSTAR data has resulted in the first robust detection of Compton hump in all three objects, with amplitudes of ∼1 or greater in NY Lup, and likely <1.0 in the other two. We also confirm earlier reports of a strong spin modulation above 10 keV in V709 Cas, and we report the first detection of small spin amplitudes in the others. We interpret this as due to different height of the X-ray emitting region among these objects. A height of ∼0.2 white dwarf radii provides a plausible explanation for the low reflection amplitude of V709 Cas. Since emission regions above both poles are visible at certain spin phases, this can alsomore » explain the strong hard X-ray spin modulation. A shock height of ∼0.05 white dwarf radii can explain our results on V1223 Sgr, while the shock height in NY Lup appears negligible.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. CRESST and X-ray Astrophysics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States)
  2. Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)
  3. New York University Abu Dhabi, P.O. Box 129188, Abu Dhabi (United Arab Emirates)
  4. INAF—Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, I-80131 Napoli (Italy)
Publication Date:
OSTI Identifier:
22518937
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 807; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DETECTION; EMISSION; HARD X RADIATION; KEV RANGE; MODULATION; NOVAE; REFLECTION; SENSITIVITY; SPIN; WHITE DWARF STARS