Hibernating black holes revealed by photometric mass functions

Casares, J.

doi:10.1093/mnras/stx2690

Cited by 30 publications

(22 citation statements)

References 106 publications

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“…Given that we likely detected a grazing eclipse in the Hα EW, the constraint on q can be used to set a lower limit to the orbital inclination, using the disc eclipse condition through e.g. equation 5 in Casares (2018). Assuming a typical disc size R d ∼ 0.5 R L1 , where R L1 stands for the equivalent radius of the compact object's Roche lobe, we obtain i 69 • .…”

Section: Discussionmentioning

confidence: 99%

Dynamical Confirmation of a Black Hole in MAXI J1820+070

Torres

Casares

Jiménez-Ibarra

et al. 2019

ApJL

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108

102

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We present time-resolved 10.4-m GTC and 4.2-m WHT intermediate resolution spectroscopy of the X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained during its decline to the quiescent state. Cross-correlation of the 21 individual spectra against late-type templates reveals a sinusoidal velocity modulation with a period of 0.68549 ± 0.00001 d and semi-amplitude of 417.7 ± 3.9 km s −1 . We derive a mass function f(M)=5.18 ± 0.15 M , dynamically confirming the black hole nature of the compact object. Our analysis of the stellar absorption features supports a K3 − 5 spectral classification for the donor star, which contributes ≈ 20% of the total flux at 5200-6800Å. The photometric 0.703 ± 0.003 d periodicity observed during outburst is 2.6 % longer than the orbital period supporting the presence of a superhump modulation in the outburst light curves. In line with this interpretation, we constrain the binary mass ratio to be q 0.12. In addition, we observe a sharp increase in the Hα emission line equivalent width during inferior conjunction of the donor star that we interpret as a grazing eclipse of the accretion disc and allows us to constrain the binary inclination to i 69 • . On the other hand, the absence of X-ray eclipses during outburst imply i 77 • . These inclination limits, together with our dynamical solution, lead to a black hole mass in the range 7-8 M . We also measure a systemic velocity γ = −21.6 ± 2.3 km s −1 which, combined with the Gaia DR2 proper motion and parallax, implies a large peculiar velocity ∼100 km s −1 .

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Section: Discussionmentioning

confidence: 99%

Dynamical Confirmation of a Black Hole in MAXI J1820+070

Torres

Casares

Jiménez-Ibarra

et al. 2019

ApJL

Self Cite

108

102

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“…Combining new radio surveys (such as the VLA Sky Survey and EMU survey with ASKAP; Norris et al 2011;Lacy et al 2019) with new X-ray surveys (e.g., eROSITA; Merloni et al 2012) is a promising way forward over the next decade. Such joint radio/X-ray campaigns will compliment ongoing efforts to detect quiescent black hole binaries, like narrow-band emission line imaging (Casares 2018) and X-ray surveys (Jonker et al 2014).…”

Section: Resultsmentioning

confidence: 94%

GS 2000+25: The Least Luminous Black Hole X-Ray Binary

Rodriguez

Urquhart

Plotkin

et al. 2020

ApJ

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Little is known about the properties of the accretion flows and jets of the lowest-luminosity quiescent black holes. We report new, strictly simultaneous radio and X-ray observations of the nearby stellarmass black hole X-ray binary GS 2000+25 in its quiescent state. In deep Chandra observations we detect the system at a faint X-ray luminosity of L X = 1.1 +1.0 −0.7 × 10 30 (d/2 kpc) 2 erg s −1 (1-10 keV). This is the lowest X-ray luminosity yet observed for a quiescent black hole X-ray binary, corresponding to an Eddington ratio L X /L Edd ∼ 10 −9 . In 15 hours of observations with the Karl G. Jansky Very Large Array, no radio continuum emission is detected to a 3σ limit of < 2.8 µJy at 6 GHz. Including GS 2000+25, four quiescent stellar-mass black holes with L X < 10 32 erg s −1 have deep simultaneous radio and X-ray observations and known distances. These sources all have radio to X-ray luminosity ratios generally consistent with, but slightly lower than, the low state radio/X-ray correlation for stellar-mass black holes with L X > 10 32 erg s −1 . Observations of these sources tax the limits of our current X-ray and radio facilities, and new routes to black hole discovery are needed to study the lowest-luminosity black holes.

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“…At this point, we cannot discriminate between the CV and LMXB interpretation. For the CV case, we constrain the donor star to white dwarf mass ratio (q) to be <0.22 for P orb < 2.2 h using the empirical exponential relation between q and P orb reported in Casares (2018). For the BH case, limits on the donor star to BH mass ratio q can be set using the correlation established for quiescent BH LMXBs between this quantity and the H α double-peak separation (DP) to FWHM ratio: log q = −23.2log (DP/FWHM) − 6.88 (Casares 2016).…”

Section: Discussionmentioning

confidence: 99%

Constraining the nature of the accreting binary in CXOGBS J174623.5−310550

Torres

Repetto

Wevers

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We report optical and infrared observations of the X-ray source CXOGBS J174623.5−310550. This Galactic object was identified as a potential quiescent low-mass X-ray binary accreting from an M-type donor on the basis of optical spectroscopy and the broad H α emission line. The analysis of X-shooter spectroscopy covering three consecutive nights supports an M2/3-type spectral classification. Neither radial velocity variations nor rotational broadening is detected in the photospheric lines. No periodic variability is found in I-and r-band light curves. We derive r = 20.8, I = 19.2, and K s ≈ 16.6 for the optical and infrared counterparts with the M-type star contributing ≈90 per cent to the I-band light. We estimate its distance to be 1.3-1.8 kpc. The lack of radial velocity variations implies that the M-type star is not the donor star in the X-ray binary. This could be an interloper or the outer body in a hierarchical triple. We constrain the accreting binary to be a 2.2 h orbital period eclipsing cataclysmic variable or a low-mass X-ray binary lying in the foreground of the Galactic bulge.

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Hibernating black holes revealed by photometric mass functions

Cited by 30 publications

References 106 publications

Dynamical Confirmation of a Black Hole in MAXI J1820+070

Dynamical Confirmation of a Black Hole in MAXI J1820+070

GS 2000+25: The Least Luminous Black Hole X-Ray Binary

Constraining the nature of the accreting binary in CXOGBS J174623.5−310550

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