Coronal X rays from single, magnetic white dwarfs - A search and probable detection

Arnaud, Keith A.; Железняков, Владимир Васильевич; Trimble, Virginia

doi:10.1086/132983

Cited by 11 publications

(5 citation statements)

References 16 publications

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“…Searches with Einstein and EXOSAT (Fontaine et al 1982;Arnaud et al 1992) and with ROSAT (Cavallo et al 1993;Musielak et al 1995) for coronal X-rays from cool white dwarfs yielded no firm detections. For searches with the ROSAT PSPC, Cavallo et al (1993) established X-ray upper limits for the white dwarfs G99-47 and G195-19;Musielak et al (1995) for GD 90, GD 356, and WD 2316+123.…”

Section: Previous X-ray Observationsmentioning

confidence: 95%

“…Several theorists (e.g., Zheleznyakov & Litvinchuk 1984;Serber 1990;Thomas, Markiel, & Van Horn 1995) have suggested that single, cool, magnetic white dwarfs might have coronae. Some observers (Fontaine, Montmerle, & Michaud 1982;Arnaud et al 1992;Cavallo, Arnaud, & Trimble 1993;Musielak, Porter, & Davis 1995;Musielak et al 2003) have previously searched for X radiation that might be emitted by hot gas above a white-dwarf photosphere. There were no persuasive detections, despite one false alarm -GR 290, in archival Einstein data (Arnaud et al 1992).…”

Section: Introductionmentioning

confidence: 99%

“…Some observers (Fontaine, Montmerle, & Michaud 1982;Arnaud et al 1992;Cavallo, Arnaud, & Trimble 1993;Musielak, Porter, & Davis 1995;Musielak et al 2003) have previously searched for X radiation that might be emitted by hot gas above a white-dwarf photosphere. There were no persuasive detections, despite one false alarm -GR 290, in archival Einstein data (Arnaud et al 1992). We here report another upper limit, more stringent than the previous ones, for the white-dwarf star GD 356.…”

Section: Introductionmentioning

confidence: 99%

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AChandraSearch for Coronal X‐Rays from the Cool White Dwarf GD 356

Weisskopf

Trimble

et al. 2007

ApJ

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108

110

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We report observations with the Chandra X-ray Observatory of the single, cool, magnetic white dwarf GD 356. For consistent comparison with other X-ray observations of single white dwarfs, we also re-analyzed archival ROSAT data for GD 356 (GJ 1205), G99-47 (GR 290 = V1201 Ori), GD 90, G195-19 (EG 250 = GJ 339.1), and WD 2316+123, and archival Chandra data for LHS 1038 (GJ 1004) and GD 358 (V777 Her). Our Chandra observation detected no X-rays from GD 356, setting the most restrictive upper limit to the X-ray luminosity from any cool white dwarf: L X < 6:0 ; 10 25 ergs s À1 , at 99.7% confidence, for a 1 keV thermal bremsstrahlung spectrum. The corresponding limit to the electron density is n 0 < 4:4 ; 10 11 cm À3 . Our re-analysis of the archival data confirmed the nondetections reported by the original investigators. We discuss the implications of our and prior observations for models of coronal emission from white dwarfs. For magnetic white dwarfs, we emphasize the more stringent constraints imposed by cyclotron radiation. In addition, we describe (in an Appendix) a statistical methodology for detecting a source and for constraining the strength of a source, which applies even when the number of source or background events is small.

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Section: Previous X-ray Observationsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

AChandraSearch for Coronal X‐Rays from the Cool White Dwarf GD 356

Weisskopf

Trimble

et al. 2007

ApJ

Self Cite

108

110

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“…Chromospheric activity (and an associated x-ray bright corona) is an obvious explanation, but no evidence for such a phenomenon has ever been detected from a magnetic white dwarf (e.g. Arnaud, Zheleznyakov andTrimble 1992, Cavallo, Arnaud andTrimble 1993). From ROSAT observations, Muielak, Porter and Davis (1995) give the upper limit on the x-ray luminosity of GD 356 at a few ×10 26 erg s −1 , the same order of magnitude as the luminosity of the solar corona.…”

Section: A Cool Spot Variability Modelmentioning

confidence: 99%

Photometric variability of the unique magnetic white dwarf GD 356

Brinkworth

Burleigh

Wynn

et al. 2004

Monthly Notices of the Royal Astronomical Society

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GD 356 is a magnetic white dwarf (B = 13MG) that uniquely displays weak resolved Zeeman triplets of H α and H β in emission. As such, GD 356 may be the only known white dwarf with some kind of chromosphere, although accretion from the interstellar medium or more exotic mechanisms cannot be ruled out. Here, we report the detection of low amplitude (± ∼ 0.2%) near-sinusoidal photometric (V -band) variability in GD 356, with a period of 0.0803 days (∼ 115 minutes). We interpret this as the rotation period of the star. We model the variability with a dark spot (by analogy with star spots) covering 10% of the stellar surface. It seems likely that this spot is also the site of the Zeeman emission, requiring the presence of a temperature inversion. We show that the spot is never totally visible or obscured, and that both polar and equatorial spots produce good fits to the data when viewed at high and low inclination respectively.

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“…To quantify the uncertainties from the dark matter density distribution, we also show the sensitivities for the generalized Navarro-Frenk-White (gNFW) profile [549,550] and a density spike near the central black hole [551,552,553]. Additionally, it is possible that some white dwarfs might be surrounded by a hot envelope in the outer part of their atmosphere, a so-called "corona" [554,555], which was originally proposed to account for observations of X-ray emission from such stars [556]. However, these observations were later revisited and found to be either consistent with emissions from the photosphere or with a nondetection [557,556,558].…”

Section: Detection Sensitivitymentioning

confidence: 99%

Feebly-interacting particles: FIPs 2020 workshop report

et al. 2021

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With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs 2020 has been the first workshop fully dedicated to the physics of feebly-interacting particles and was held virtually from 31 August to 4 September 2020. The workshop has gathered together experts from collider, beam dump, fixed target experiments, as well as from astrophysics, axions/ALPs searches, current/future neutrino experiments, and dark matter direct detection communities to discuss progress in experimental searches and underlying theory models for FIPs physics, and to enhance the cross-fertilisation across different fields. FIPs 2020 has been complemented by the topical workshop “Physics Beyond Colliders meets theory”, held at CERN from 7 June to 9 June 2020. This document presents the summary of the talks presented at the workshops and the outcome of the subsequent discussions held immediately after. It aims to provide a clear picture of this blooming field and proposes a few recommendations for the next round of experimental results.

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Coronal X rays from single, magnetic white dwarfs - A search and probable detection

Cited by 11 publications

References 16 publications

AChandraSearch for Coronal X‐Rays from the Cool White Dwarf GD 356

AChandraSearch for Coronal X‐Rays from the Cool White Dwarf GD 356

Photometric variability of the unique magnetic white dwarf GD 356

Feebly-interacting particles: FIPs 2020 workshop report

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