The Binary Mass Ratio in the Black Hole Transient MAXI J1820+070

Abstract

We present intermediate resolution spectroscopy of the optical counterpart to the black hole X-ray transient MAXI J1820+070 (=ASASSN-18ey) obtained with the OSIRIS spectrograph on the 10.4-m Gran Telescopio Canarias. The observations were performed with the source close to the quiescent state and before the onset of renewed activity in August 2019. We make use of these data and K-type dwarf templates taken with the same instrumental configuration to measure the projected rotational velocity of the donor star. We find v rot sin i = 84±5 km s −1 (1−σ), which implies a donor to black-hole mass ratio q = M 2 /M 1 = 0.072 ± 0.012 for the case of a tidally locked and Roche-lobe filling donor star. The derived dynamical masses for the stellar components are M 1 = (5.95 ± 0.22) sin −3 i M and M 2 = (0.43 ± 0.08) sin −3 i M . The use of q, combined with estimates of the accretion disk size at the time of the optical spectroscopy, allows us to revise our previous orbital inclination constraints to 66 • < i < 81 • . These values lead to 95% confidence level limits on the masses of 5.73 < M 1 (M ) < 8.34 and 0.28 < M 2 (M ) < 0.77. Adopting instead the 63 ± 3 • orientation angle of the radio jet as the binary inclination leads to M 1 = 8.48 +0.79 −0.72 M and M 2 = 0.61 +0.13 −0.12 M (1−σ).

Near-infrared emission lines trace the state-independent accretion disc wind of the black hole transient MAXI J1820+070

“…Mata Sánchez et al 2018). In this letter, we present eight epochs of high-quality near-infrared (NIR) spectroscopy supporting the presence of a cold accretion disc wind during both the hard and soft states of this dynamically confirmed (Torres et al 2019(Torres et al , 2020 BH transient.…”

MAXI J1820+070 with NuSTAR – II. Flaring during the hard to soft state transition with a long soft lag

“…It was confirmed to host a black hole by Torres et al (2019). Further measurements (Torres et al 2020) refine the mass estimate to 5.7 < MBH/M < 9.5, depending on the assumed binary inclination. The most precise distance measured to date is 2.96 ± 0.33 kpc from radio parallax (Atri et al 2020); this is consistent with the optical parallax from GAIA (3.5 +2.2 −1.0 kpc, Bailer-Jones et al 2018; Gandhi et al 2019).…”

Searching for stellar-mass black holes in the Milky Way

“…图1给出了已探测的银河系中恒 星级黑洞的分布情况 [10] , 其中圆圈代表已证认的黑洞, 洞X射线双星的缩略图 [8] . 表1给出了银河系中已证认 的20个黑洞X射线双星的名称、轨道周期和黑洞质 量 [4,10,[12][13][14] .…”

“…数据主要 取自参考文献[10]. 此外, GRS 1124-684的数据取自参考文 献[12,13], MAXI J1820+070的数据取自参考文献[14], Cyg X-1的数据取自参考文献[4] Information of 20 confirmed black hole X-ray binaries. The data are mainly taken from ref.[10].…”

“…In addition, the data of GRS 1124-684, MAXI J1820+070, and Cyg X-1 are taken from refs [12,13],. ref [14],. and ref.…”