scholarly journals Periodic X-ray sources in the Galactic bulge: application of the Gregory–Loredo algorithm

2020 ◽  
Vol 498 (3) ◽  
pp. 3513-3534
Author(s):  
Tong Bao ◽  
Zhiyuan Li
Keyword(s):  
Detection Efficiency ◽  
Cataclysmic Variables ◽  
Light Curves ◽  
Solar Neighbourhood ◽  
Large Set ◽  
Galactic Bulge ◽  
Period Range ◽  
Apparent Lack ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

ABSTRACT We present a systematic study of periodic X-ray sources in the Limiting Window (LW), a ∼70 arcmin2 field representative of the inner Galactic bulge and the target of ∼1 Ms Chandra observations. Using the Gregory–Loredo algorithm, which applies Bayes’s theorem to the phase-folded light curve and is well suited for irregularly sampled X-ray data, we detect 25 periodic signals in 23 discrete sources, among which 15 signals are new discoveries and two sources show dual periods. The vast majority of the 23 periodic sources are classified as magnetic cataclysmic variables (CVs), based on their period range, X-ray luminosities, spectral properties, and phase-folded light curves that are characteristic of spin modulation. Meanwhile, there is a paucity of non-magnetic CVs seen as periodic sources, which can be understood as due to a low detection efficiency for eclipsing sources. Under reasonable assumptions about the geometry of magnetic CVs and a large set of simulated X-ray light curves, we estimate the fraction of magnetic CVs in the inner Galactic bulge to be ≲23 per cent, which is similar to that in the solar neighbourhood. There is an apparent lack of long-period (≳3.3 h) CVs in the LW, when contrasted with the range of known CVs in the solar neighbourhood. We suggest that this might be an age effect, in the sense that CVs in the inner bulge are more evolved systems and have substantially shrunk their orbits.

scholarly journals Hard X-ray Observations of Magnetic Cataclysmic Variables

2004 ◽  
Vol 190 ◽  
pp. 135-141 ◽  
Author(s):  
K. P. Singh ◽  
V. R. Rana ◽  
K. Mukerjee ◽  
P. Barrett ◽  
E. M. Schlegel
Keyword(s):  
Cataclysmic Variables ◽  
Type Systems ◽  
Light Curves ◽  
Average Intensity ◽  
Spectral Parameters ◽  
X Ray ◽  
Orbital Modulation ◽  
Magnetic Cataclysmic Variables ◽  
The Masses ◽  
First Time

AbstractHard X-ray light curves and spectral parameters from our analysis of X-ray data of five AM Her type systems – V2301 Oph, V1432 Aql, EP Draconis, GG Leonis, & V834 Cen, and one intermediate polar – TV Col, observed using the Rossi X — ray Timing Explorer (RXTE) satellite are presented. A new improved ephemeris has been derived for V2301 Oph using the mid-eclipse timings. Average intensity variations, without any change of shape of the light curve or hardness ratio, are observed on timescales of a few days to a few months in V2301 Oph. V1432 Aql shows erratic variations on a timescale of a day, at least two sharp dips near orbital phases 0.35 and 0.5, and a total eclipse. Hard X-ray eclipses are also reported in EP Dra and GG Leo. V834 Cen shows intensity variations on yearly timescale and is found to be in a low state in 2002. In TV Col, a binary orbital modulation at 5.5h, in addition to the spin period of 1910s, is reported for the first time. Maximum spectral temperatures in Polars have been determined and used to estimate the masses of the white dwarfs.

scholarly journals Extreme Ultraviolet Spectroscopy of Magnetic Cataclysmic Variables

1996 ◽  
Vol 152 ◽  
pp. 309-316
Author(s):  
Frits Paerels ◽  
Min Young Hur ◽  
Christopher W. Mauche
Keyword(s):  
High Resolution ◽  
White Dwarf ◽  
Extreme Ultraviolet ◽  
Cataclysmic Variables ◽  
Ultraviolet Spectroscopy ◽  
Temperature Structure ◽  
Polar Cap ◽  
Ultraviolet Emission ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

A longstanding problem in the interpretation of the X-ray and extreme ultraviolet emission from strongly magnetic cataclysmic variables can be addressed definitively with high resolution EUV spectroscopy. A detailed photospheric spectrum of the accretion-heated polar cap of the white dwarf is sensitive in principle to the temperature structure of the atmosphere. This may allow us to determine where and how the bulk of the accretion energy is thermalized. The EUVE data on AM Herculis and EF Eridani are presented and discussed in this context.

X-ray emission from non-magnetic cataclysmic variables

Nature ◽  
1984 ◽  
Vol 308 (5959) ◽  
pp. 519-521 ◽  
Author(s):  
A. R. King ◽  
G. Shaviv
Keyword(s):  
Cataclysmic Variables ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

scholarly journals X-Ray Emission from Non-Magnetic Cataclysmic Variables

1987 ◽  
Vol 93 ◽  
pp. 225-233
Author(s):  
H. Van Der Woerd
Keyword(s):  
Boundary Layer ◽  
Spectral Characteristics ◽  
Cataclysmic Variables ◽  
Large Sample ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

AbstractEXOSAT observations of a large sample of non-magnetic cataclysmic variables have led to the detection of VW Hyi and OY Car as strong soft X-ray sources during superoutburst. The spectral characteristics of the X-ray emission of these SU Uma systems are compared. It is proposed that both systems have, besides a cool, optically thick boundary layer, an extended hot, optically thin corona.

scholarly journals X-Ray Observations of Cataclysmic Variables

1987 ◽  
Vol 93 ◽  
pp. 207-223
Author(s):  
J.P. Osborne
Keyword(s):  
Light Curve ◽  
Spectral Range ◽  
Cataclysmic Variables ◽  
High Sensitivity ◽  
Light Curves ◽  
X Ray ◽  
Broad Spectral Range ◽  
Intermediate Polars ◽  
Recurrent Nova

AbstractThe X-ray observatory EXOSAT spent over 1000 hours observing cataclysmic variables. Some of the major results reviewed here are: soft X-ray light curve changes in AM Her objects, orbital effects in the X-ray light curves of intermediate polars and U Gem, regular behaviour in the inter-outburst X-ray flux of VW Hyi, and X-ray emission from the tenuous remnant of the recent recurrent nova RS Oph. The ability of EXOSAT to make long uninterupted observations at high sensitivity over a broad spectral range and to react quickly to cosmic events has yielded a dataset of a quality that will not be surpassed for many years.

scholarly journals Hard X-ray properties of magnetic cataclysmic variables

2010 ◽  
Author(s):  
S. Scaringi ◽  
A. J. Bird ◽  
A. J. Norton ◽  
C. Knigge ◽  
A. B. Hill ◽  
...  
Keyword(s):  
Cataclysmic Variables ◽  
X Ray ◽  
Magnetic Cataclysmic Variables

scholarly journals Optical Studies of 10 Hard X-Ray-selected Cataclysmic Binaries

2022 ◽  
Vol 924 (2) ◽  
pp. 67
Author(s):  
Jules P. Halpern ◽  
John R. Thorstensen
Keyword(s):  
Cataclysmic Variables ◽  
Velocity Variation ◽  
Time Resolved ◽  
X Ray ◽  
Spin Period ◽  
Radial Velocity Variation ◽  
Cataclysmic Binaries ◽  
Orbital Periods ◽  
Magnetic Cataclysmic Variables ◽  
Optical Identifications

Abstract We conducted time-resolved optical spectroscopy and/or photometry of 10 cataclysmic binaries that were discovered in hard X-ray surveys, with the goal of measuring their orbital periods and searching for evidence that they are magnetic. Four of the objects in this study are new optical identifications: IGR J18017−3542, PBC J1841.1+0138, IGR J18434−0508, and Swift J1909.3+0124. A 311.8 s, coherent optical pulsation is detected from PBC J1841.1+0138, as well as eclipses with a period of 0.221909 days. A 152.49 s coherent period is detected from IGR J18434−0508. A probable period of 389 s is seen in IGR J18151−1052, in agreement with a known X-ray spin period. We also detect a period of 803.5 s in an archival X-ray observation of Swift J0717.8−2156. The last four objects are thus confirmed magnetic cataclysmic variables of the intermediate polar class. An optical period of 1554 s in AX J1832.3−0840 also confirms the known X-ray spin period, but a stronger signal at 2303 s is present whose interpretation is not obvious. We also studied the candidate intermediate polar Swift J0820.6−2805, which has low and high states differing by ≈4 mag and optical periods or quasi-periodic oscillations not in agreement with proposed X-ray periods. Of note is an unusually long 2.06-day orbital period for Swift J1909.3+0124, manifest in the radial velocity variation of photospheric absorption lines of an early K-type companion star. The star must be somewhat evolved if it is to fill its Roche lobe.

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