SPH Simulations of Direct Impact Accretion in the Ultracompact AM CVn Binaries

Dolence, Joshua C.; Wood, M. A.; Silver, Isaac M.

doi:10.1086/589817

Cited by 8 publications

(6 citation statements)

References 50 publications

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“…The density of the accreted material is high enough to penetrate below the surface and thermalize to soft X-rays. This is confirmed by use of a smoothparticle hydrodynamics (SPH) code by Dolence et al (2008) using system parameters proposed by Marsh & Steeghs (2002). The supersonic stream impacts the white dwarf atmosphere in a near horizontal trajectory.…”

Section: Direct-impact Modelmentioning

confidence: 64%

AM CVn Stars: Status and Challenges

Solheim

2010

PUBL ASTRON SOC PAC

200

189

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AM CVn stars are the outcome of a fine-tuned binary star evolution pathway. They are helium-rich and their binary orbital periods are less than 65 minutes. They evolve through one or two common envelope (CE) events, which are difficult to model. Observations of AM CVn stars are important to understand the CE phase. Thanks to intensive observing campaigns, the number of AM CVn stars has increased from 5 to 25 during the last 15 yr. We have witnessed long photometric campaigns, time-resolved spectroscopy, UV and X-ray observations, and progress in modeling of the internal structure of donor and accretor stars, disk structure, disk atmosphere, and their evolution. Two possible new members of the AM CVn family have orbital periods of less than 10 minutes. For these, four different models have been proposed, including one without mass transfer, driven by electricity generated by the secondary star moving in the magnetic field of the primary. Short-period AM CVn stars are among the first possible detectable sources of low-frequency gravitational wave (GW) radiation. They are also possible progenitors of a Type Ia supernova (SN Ia) and subluminous explosions, and they can produce helium novae during their evolution. From systematic searches in the Sloan Digital Sky Survey, it has been possible to estimate population densities that can be tested against population synthesis models. One important question to investigate is the relative importance of the three proposed birth channels: a low-mass white dwarf donor, a helium-star donor, or a highly evolved cataclysmic variable (CV) as a donor. A review of the research on AM CVn stars covering the last 15 yr is given, and the outlook for future research is discussed.

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Section: Direct-impact Modelmentioning

confidence: 64%

AM CVn Stars: Status and Challenges

Solheim

2010

PUBL ASTRON SOC PAC

200

189

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“…This could be a clue to the location and extent of the emission region. For instance, Dolence et al (2008) and Wood (2009) modelled the Xray and optical phase folded light curves to place constraints on the extent of the X-ray generating spot assuming a direct impact model.…”

Section: Discussionmentioning

confidence: 99%

Detection of a 23.6 min periodic modulation in the optical counterpart of 3XMMJ051034.6–670353

Ramsay

Marsh

Kupfer

et al. 2018

A&A

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We present high speed optical photometric observations made using the NTT and ULTRACAM of the optical counterpart of 3XMMJ051034.6-670353, which was recently identified as an X-ray source showing a modulation on a period of 23.6 min. Although the optical counterpart is faint (g=21.4), we find that the u ′ g ′ r ′ light curves show a periodic modulation on a period which is consistent with the X-ray period. We also obtained three low resolution spectra of 3XMMJ051034.6-670353 using the Gemini South Telescope and GMOS. There is no evidence for strong emission lines in the optical spectrum of 3XMMJ051034.6-670353. We compare and contrast the optical and X-ray observations of 3XMMJ051034.6-670353 with the ultra compact binaries HM Cnc and V407 Vul. We find we can identify a distribution of binary masses in which stable direct impact accretion can occur.

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“…Other than the possible emission lines in HM Cnc, no optically thin component has been detected. There does not appear to be a quantitative study of whether the lack of optically thin X-rays is to be expected in the direct impact shock regions, given the likely white dwarf mass and the specific accretion rate (Dolence, Wood & Silver 2008). The phasing of the optical and Xray light curves, and the long-term period history derived from repeated X-ray observations (see, e.g., Ramsay et al 2005) of HM Cnc and V407 Vul are consistent with the direct impact accretor model.…”

Section: X-rays From Am Cvn Systemsmentioning

confidence: 99%

X-Ray Emissions from Accreting White Dwarfs: A Review

Mukai

2017

PASP

251

212

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Interacting binaries in which a white dwarf accretes material from a companion-cataclysmic variables (CVs) in which the mass donor is a Roche-lobe filling star on or near the main sequence, and symbiotic stars in which the mass donor is a late type giant-are relatively commonplace. They display a wide range of behaviors in the optical, X-rays, and other wavelengths, which still often baffle observers and theorists alike. Here I review the existing body of research on X-ray emissions from these objects for the benefits of both experts and newcomers to the field. I provide introductions to the past and current X-ray observatories, the types of known X-ray emissions from these objects, and the data analysis techniques relevant to this field. I then summarize of our knowledge regarding the X-ray emissions from magnetic CVs, non-magnetic CVs and symbiotic stars, and novae in eruption. I also discuss space density and the X-ray luminosity functions of these binaries and their contribution to the integrated X-ray emission from the Galaxy. I then discuss open questions and future prospects.

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SPH Simulations of Direct Impact Accretion in the Ultracompact AM CVn Binaries

Cited by 8 publications

References 50 publications

AM CVn Stars: Status and Challenges

AM CVn Stars: Status and Challenges

Detection of a 23.6 min periodic modulation in the optical counterpart of 3XMMJ051034.6–670353

X-Ray Emissions from Accreting White Dwarfs: A Review

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