scholarly journals A spider timing model: accounting for quadrupole deformations and relativity in close pulsar binaries

2019 ◽  
Vol 492 (2) ◽  
pp. 1550-1565 ◽  
Author(s):  
Guillaume Voisin ◽  
René P Breton ◽  
Charlotte Summers
Keyword(s):  
Cataclysmic Variables ◽  
Quadrupole Deformation ◽  
Orbital Eccentricity ◽  
Companion Star ◽  
Compact Binaries ◽  
Timing Model ◽  
Pulsar Timing ◽  
Low Mass ◽  
Stellar Interiors ◽  
Made In

ABSTRACT Spider millisecond pulsars are, along with some eclipsing post-common envelope systems and cataclysmic variables, part of an expanding category of compact binaries with low-mass companions for which puzzling timing anomalies have been observed. The most prominent type of irregularities seen in them are orbital period variations, a phenomenon which has been proposed to originate from changes in the gravitational quadrupole moment of the companion star. A physically sound modelling of the timing of these systems is key to understanding their structure and evolution. In this paper we argue that a complete timing model must account for relativistic corrections as well as rotationally and tidally induced quadrupole distortions. We solve for the resulting orbital dynamics using perturbation theory and derive the corresponding timing model in the low eccentricity limit. We find that the expected strong quadrupole deformation of the companion star results in an effective minimum orbital eccentricity. It is accompanied by a fast periastron precession which, if not taken into account, averages out any measurement of the said eccentricity. We show that, with our model, detection of both eccentricity and precession is likely to be made in many if not all spider pulsar systems. Combined with optical light curves, this will allow us to measure the apsidal motion constant, connecting the quadrupole deformation to the internal structure, and thus opening a new window into probing the nature of their exotic stellar interiors. Moreover, more accurate timing may eventually lead spider pulsars to be used for high-precision timing experiments such as pulsar timing arrays.

scholarly journals Using X-Rays to Probe the Compact Binary Content of Globular Clusters

2004 ◽  
Vol 194 ◽  
pp. 75-76
Author(s):  
N. A. Webb ◽  
B. Gendre ◽  
D. Barret
Keyword(s):  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Close Binaries ◽  
X Rays ◽  
X Ray ◽  
Compact Binaries ◽  
Compact Binary ◽  
Low Mass ◽  
Evolutionary Paths ◽  
New Generation

AbstractGlobular clusters (GCs) harbour a large number of close binaries which are hard to identify optically due to high stellar densities. Observing these GCs in X-rays, in which the compact binaries are bright, diminishes the over-crowding problem. Using the new generation of X-ray observatories, it is possible to identify populations of neutron star low mass X-ray binaries, cataclysmic variables and millisecond pulsars as well as other types of binaries. We present the spectra of a variety of binaries that we have identified in four GCs observed by XMM-Newton. We show that through population studies we can begin to understand the formation of individual classes of binaries in GCs and hence start to unfold the complex evolutionary paths of these systems.

scholarly journals Secular Evolution of Cataclysmic Variables with Irradiation-Induced Mass Transfer

1996 ◽  
Vol 158 ◽  
pp. 449-452 ◽  
Author(s):  
H. Ritter ◽  
Z. Zhang ◽  
J. M. Hameury
Keyword(s):  
Mass Transfer ◽  
Cataclysmic Variables ◽  
Point Of View ◽  
External Irradiation ◽  
General Point ◽  
Mass Star ◽  
Compact Binaries ◽  
Secular Evolution ◽  
Low Mass

The possible importance of the reaction of a low-mass star to external irradiation for the long-term evolution of compact binaries has been noted only rather recently; first in the context of the evolution of low-mass X-ray binaries (e.g. Podsiadlowski 1991; Harpaz & Rappaport 1991; Frank, King & Lasota 1992; Hameury et al. 1993) and subsequently by Ritter, Zhang & Kolb (1995a,b, hereafter RZK) also for the evolution of cataclysmic variables (CVs). Based on a simple model for describing the reaction of a low-mass star to irradiation RZK showed that CVs can be dynamically unstable against irradiation-induced mass transfer and that, as a consequence of this, mass transfer could occur via cycles in which phases of high, irradiation-enhanced mass transfer alternate with phases of little or no mass transfer. The occurrence of such mass transfer cycles in CVs was subsequently discussed from a more general point of view by King (1995) and King et al. (1995). Whereas the possibility of mass transfer cycles in CVs is now fully recognised, the question as to which systems can undergo such cycles and which cannot has not yet been addressed in detail. It is the purpose of this contribution to provide at least a partial answer to this question.

scholarly journals Accretion Effects on Disks Around Non-Magnetic Compact Objects

2012 ◽  
Vol 8 (S290) ◽  
pp. 279-280
Author(s):  
Michele M. Montgomery
Keyword(s):  
Accretion Disks ◽  
Mass Transfer Rate ◽  
Cataclysmic Variables ◽  
Compact Objects ◽  
Additional Time ◽  
Compact Binaries ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Low Mass ◽  
Magnetic Cataclysmic Variables

AbstractAccretion disks in compact binaries are thought to sometimes tilt and precess in the retrograde direction as indicated by modulations in light curves and/or signals. Using 3D Smoothed Particle Hydrodynamics and a low mass transfer rate, Montgomery (2012) shows the disk in non-magnetic Cataclysmic Variables tilts naturally after enough time has passed. In that work, twice the fundamental negative superhump signal 2ν_ is associated with disk tilt around the line of nodes, gas stream overflow approximately twice per orbital period, and retrograde precession. In this work, we show that after enough additional time has passed in the same simulation, the 4ν_ harmonic appears. The decrease in the 2ν_ amplitude approximately equals the amplitude of the 4ν_ harmonic. We discuss the implications.

scholarly journals Magnetic Braking in Cataclysmic and Low-Mass X-Ray Binaries

1984 ◽  
Vol 80 ◽  
pp. 287-294
Author(s):  
O. Vilhu
Keyword(s):  
Mass Transfer ◽  
Binary Stars ◽  
Cataclysmic Variables ◽  
Turnover Time ◽  
Coronal Emission ◽  
X Ray ◽  
Compact Binaries ◽  
Gradual Loss ◽  
Low Mass ◽  
Magnetic Braking

AbstractThe chromospheric-coronal emission of lower Main-Sequence single and binary stars can be correlated with an activity parameter of type R = g(B-V)P-1 where P is the rotation or orbital period and g(B-V) a function of the color resembling the convective turnover time. Observations indicate that the active region area coverage filling factor grows as R2, and the whole stellar surface becomes filled with closed loop structures at R ≂ 3. A braking formula is proposed (Equation 4) to include all periods (0.d1 ≲ R ≳ 30d) and spectral types F-M. On the basis of this equation, the mass transfer rates in compact binaries (driven by the gradual loss of orbital angular momentum) are discussed. It is concluded that the magnetic braking has good chances of being that mechanism which drives the mass transfer in cataclysmic variables and galactic bulge X-ray sources.

scholarly journals QPOs in compact binaries from small scale eruptions in an inner magnetized disk

2020 ◽  
Author(s):  
Nicolas Scepi ◽  
Mitchell C Begelman ◽  
Jason Dexter
Keyword(s):  
Rapid Heating ◽  
Small Scale ◽  
Type B ◽  
Periodic Oscillations ◽  
X Ray ◽  
Compact Binaries ◽  
Heating And Cooling ◽  
Low Mass ◽  
X Ray Binaries ◽  
Standard Disk

Abstract Dwarf novæ (DNe) and low mass X-ray binaries (LMXBs) are compact binaries showing variability on time scales from years to less than seconds. Here, we focus on explaining part of the rapid fluctuations in DNe, following the framework of recent studies on the monthly eruptions of DNe that use a hybrid disk composed of an outer standard disk and an inner magnetized disk. We show that the ionization instability, that is responsible for the monthly eruptions of DNe, is also able to operate in the inner magnetized disk. Given the low density and the fast accretion time scale of the inner magnetized disk, the ionization instability generates small, rapid heating and cooling fronts propagating back and forth in the inner disk. This leads to quasi-periodic oscillations (QPOs) with a period of the order of 1000 s. A strong prediction of our model is that these QPOs can only develop in quiescence or at the beginning/end of an outburst. We propose that these rapid fluctuations might explain a subclass of already observed QPOs in DNe as well as a, still to observe, subclass of QPOs in LMXBs. We also extrapolate to the possibility that the radiation pressure instability might be related to Type B QPOs in LMXBs.

scholarly journals X-ray sources in Galactic globular clusters and old open clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 367-376
Author(s):  
Maureen van den Berg
Keyword(s):  
Globular Clusters ◽  
Cataclysmic Variables ◽  
Star Clusters ◽  
Open Clusters ◽  
Encounter Rate ◽  
X Ray ◽  
Low Mass ◽  
New Perspective ◽  
X Ray Binaries ◽  
Cluster Age

AbstractThe features and make up of the population of X-ray sources in Galactic star clusters reflect the properties of the underlying stellar environment. Cluster age, mass, stellar encounter rate, binary frequency, metallicity, and maybe other properties as well, determine to what extent we can expect a contribution to the cluster X-ray emission from low-mass X-ray binaries, millisecond pulsars, cataclysmic variables, and magnetically active binaries. Sensitive X-ray observations withXMM-Newton and certainlyChandra have yielded new insights into the nature of individual sources and the effects of dynamical encounters. They have also provided a new perspective on the collective X-ray properties of clusters, in which the X-ray emissivities of globular clusters and old open clusters can be compared to each other and to those of other environments. I will review our current understanding of cluster X-ray sources, focusing on star clusters older than about 1 Gyr, illustrated with recent results.

scholarly journals An additional pulsating mode (7.35 mHz) and pulsations timing variations of PG 1613+426

2017 ◽  
Vol 26 (1) ◽  
Author(s):  
Tomomi Otani ◽  
Terry D. Oswalt ◽  
Patrice Majewski ◽  
Riley Jordan ◽  
Marc Amaral ◽  
...  
Keyword(s):  
Confidence Level ◽  
Instability Strip ◽  
Photometric Analysis ◽  
Companion Star ◽  
Pulsation Mode ◽  
Sdb Stars ◽  
Low Mass

AbstractWe present the detection of an additional pulsation mode (7.35 mHz) of a subdwarf B star, PG 1613+426, and periodic Observed minus Calculated (O-C) variations for two existing pulsations. PG 1613+426 is near the hot end of the sdB instability strip. One pulsation mode (6.94 mHz) was detected so far by Bonanno et al. (2002) and another pulsation mode candidate (7.05 mHz) was proposed with a confidence level above 90% by Kuassivi and Ferlet (2005). To constrain sdB star evolutional scenarios, this star was monitored in 2010, 2011, 2015, and 2017 as a part of a project for finding companions to sdB stars using the pulsation timing method. The photometric analysis of those data shows an additional 7.35 mHz pulsation mode as well as the previously detected 6.93 mHz mode. However the 7.05 mHz mode was not detected. Nightly amplitude changes of 7.35 mHz mode were observed in the 2011 data, however the 2017 data did not show nightly amplitude shifts. O-C variations were detected in both 6.93 mHz and 7.35 mHz pulsations, indicating that PG 1613+426 may have a low mass companion star. However, more observations are needed to confirm it.

scholarly journals Pulsar timing measurements with the 32-m TCfA radiotelescope

2000 ◽  
Vol 177 ◽  
pp. 63-64
Author(s):  
W. Lewandowski ◽  
M. Konacki ◽  
M. Redmerska ◽  
G. Feiler ◽  
A. Wolszczan
Keyword(s):  
Single Pulse ◽  
Medium Size ◽  
Orbital Inclination ◽  
Dual Channel ◽  
Timing Precision ◽  
Pulsar Timing ◽  
Short Period ◽  
Penn State ◽  
Low Mass ◽  
Timing Noise

Accurate, long-term timing measurements of pulsars provide a powerful method to study a variety of astrophysical phenomena. For “normal”, slow pulsars, the dominant factors that limit the timing precision are the intrinsic timing noise and single pulse “jitter” (e.g. Cordes 1993). In fact, because the pulse jitter surpasses radiometer noise for sufficiently strong pulsars and no further improvement of the timing precision can be achieved by increasing the antenna gain, the timing of such sources can be very efficiently conducted with suitably equipped medium-size radiotelescopes.We have been timing slow pulsars with the 32-m TCfA radiotelescope in Toruń, Poland, since July 1996, using a dual-channel, circular polarization L-band receiving system at frequencies around 1.7 GHz, and a 2 × 64 × 3 MHz channel pulsar backend, the Penn State Pulsar Machine - 2 (PSPM-2; for more details, see Konacki et al. 1999). Our gradually expanding source list currently includes 88 pulsars timed once a week with a millisecond precision using the observatory’s UTC-calibrated H-maser clock. Data analysis is routinely performed with the TEMPO software package. With a particularly dense, weekly sampling and a ≤1 ms timing precision, the TCfA program has a sensitivity to detect previously overlooked short period, low orbital inclination binaries, as well as very low-mass, planetary companions. In addition, it will be very useful in identifying and monitoring pulsar timing glitches and other forms of the timing noise.

scholarly journals Theory of Accretion Disk Coronae

1990 ◽  
Vol 115 ◽  
pp. 187-196
Author(s):  
T. R. Kallman
Keyword(s):  
Active Galactic Nuclei ◽  
Accretion Disk ◽  
Cataclysmic Variables ◽  
Galactic Nuclei ◽  
X Ray ◽  
Spectral Signatures ◽  
Low Mass ◽  
X Ray Absorption ◽  
X Ray Binaries ◽  
Theoretical Issues

AbstractAccretion disk coronae are likely to be the dominant site for X-ray absorption and reprocessed emission in low mass X-ray binaries, and may be present in other classes of compact X-ray sources such as active galactic nuclei and cataclysmic variables. In spite of this fact, and in spite of the observational evidence for their existence, there remain many uncertainties about the structure of accretion disk coronae. This paper will discuss the coronal structure and dynamics, their X-ray spectral signatures including coupling to the variability behavior of compact X-ray sources, and the major unsolved theoretical issues surrounding them.

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