Optical Studies of 15 Hard X-Ray Selected Cataclysmic Binaries

Journal Article · Fri Jun 01 04:00:00 EDT 2018 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AABFD0· OSTI ID:22897497

Halpern, Jules P.; Cho, Patricia; Collver, Gabriel ^[1]; Thorstensen, John R. ^[2]; Motsoaledi, Mokhine; Breytenbach, Hannes; Woudt, Patrick A. ^[3]; Buckley, David A. H. ^[4]

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1. Department of Astronomy, Columbia University, 550 West 120th Street, New York, NY 10027 (United States)
2. Department of Physics and Astronomy, Dartmouth College, Hanover NH 03755 (United States)
3. Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa)
4. South African Astronomical Observatory, P.O. Box 9, Observatory 7935, Cape Town (South Africa)

We conducted time-resolved optical spectroscopy and/or time-series photometry of 15 cataclysmic binaries that were discovered in hard X-ray surveys by the Swift Burst Alert Telescope and the International Gamma-Ray Astrophysics Laboratory, with the goal of measuring their orbital periods and searching for spin periods. Four of the objects in this study are new optical identifications: Swift J0535.2+2830, Swift J2006.4+3645, IGR J21095+4322, and Swift J2116.5+5336. Coherent pulsations are detected from three objects for the first time, Swift J0535.2+2830 (1523 s), 2PBC J1911.4+1412 (747 s), and 1SWXRT J230642.7+550817 (464 s), indicating that they are intermediate polars (IPs). We find two new eclipsing systems in time-series photometry: 2PBC J0658.0−1746, a polar with a period of 2.38 hr, and Swift J2116.5+5336, a disk system that has an eclipse period of 6.56 hr. Exact or approximate spectroscopic orbital periods are found for six additional targets. Of note is the long 4.637-day orbit for Swift J0623.9−0939, which is revealed by the radial velocities of the photospheric absorption lines of the secondary star. We also discover a 12.76 hr orbital period for RX J2015.6+3711, which confirms that the previously detected 2.00 hr X-ray period from this star is the spin period of an IP, as inferred by Coti Zelati et al. These results support the conclusion that hard X-ray selection favors magnetic CVs, with IPs outnumbering polars.

• OSTI ID: 22897497
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 6 Vol. 155; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
ASTROPHYSICS
ECLIPSE
GAMMA RADIATION
HARD X RADIATION
NOVAE
ORBITS
PHOTOMETRY
PULSATIONS
RADIAL VELOCITY
SPECTROSCOPY
TELESCOPES
TIME RESOLUTION