Mon. Not. R. Astron. Soc., 470, 4815-4837 (2017/October-1)
Broad-band characteristics of seven new hard X-ray selected cataclysmic variables.
BERNARDINI F., DE MARTINO D., MUKAI K., RUSSELL D.M., FALANGA M., MASETTI N., FERRIGNO C. and ISRAEL G.
Abstract (from CDS):
We present timing and spectral analysis of a sample of seven hard X-ray selected cataclysmic variable candidates based on simultaneous X-ray and optical observations collected with XMM-Newton, complemented with Swift/BAT and INTEGRAL/IBIS hard X-ray data and ground-based optical photometry. For six sources, X-ray pulsations are detected for the first time in the range of ∼296-6098 s, identifying them as members of the magnetic class. Swift J0927.7-6945, Swift J0958.0-4208, Swift J1701.3-4304, Swift J2113.5+5422 and possibly PBC J0801.2-4625 are intermediate polars (IPs), while Swift J0706.8+0325 is a short (1.7 h) orbital period polar, the 11th hard X-ray-selected identified so far. X-ray orbital modulation is also observed in Swift J0927.7-6945 (5.2 h) and Swift J2113.5+5422 (4.1 h). Swift J1701.3-4304 is discovered as the longest orbital period (12.8 h) deep eclipsing IP. The spectra of the magnetic systems reveal optically thin multitemperature emission between 0.2 and 60 keV. Energy-dependent spin pulses and the orbital modulation in Swift J0927.7-6945 and Swift J2113.5+5422 are due to intervening local high-density absorbing material (NH ∼ 10^22 - 23^ cm–2). In Swift J0958.0-4208 and Swift J1701.3-4304, a soft X-ray blackbody (kT ∼ 50 and ∼80 eV) is detected, adding them to the growing group of 'soft' IPs. White dwarf masses are determined in the range of ∼ 0.58-1.18 M☉, indicating massive accreting primaries in five of them. Most sources accrete at rates lower than the expected secular value for their orbital period. Formerly proposed as a long-period (9.4 h) nova-like CV, Swift J0746.3-1608 shows peculiar spectrum and light curves suggesting either an atypical low-luminosity CV or a low-mass X-ray binary.
© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
novae, cataclysmic variables - white dwarfs - X-rays: binaries - X-rays: individual: Swift J0706.8+0325 - X-rays: individual: Swift J0746.3-1608 (aka 1RXS J074616.8-161127) - X-rays: individual: Swift J0927.7-6945 - X-rays: individual: Swift J0958.0-4208 - X-rays: individual: PBC J0801.2-4625 (aka 1RXS J080114.6-462324) - X-rays: individual: Swift Swift J1701.3-4304 (aka IGR J17014-4306) - X-rays: individual: Swift J2113.5+5422 - X-rays: individual: Swift J2113.5+5422
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