30 research outputs found
Probing black hole X-ray binaries with the Keck telescopes
The advent of the large effective apertures of the Keck telescopes has
resulted in the determination with unprecedented accuracy of the mass functions
and mass ratios of faint (R ~ 21 mag) X-ray transients (GS 2000+25, GRO
J0422+32, Nova Oph 1977, Nova Vel 1993), as well as constraining the
main-sequence companion star parameters and producing images of the accretion
disks around the black holes.Comment: 7 pages, 4 figures, SPIE Symposium 4005, in pres
A Doppler Map and Mass-ratio Constraint for the Black-Hole X-ray Nova Ophiuchi 1977
We have reanalyzed Keck observations of Nova Oph 1977 to extend the work done
by Filippenko et al. (1997), who recently determined a mass function f(M_x) =
4.86 +/- 0.13 M_o for the compact object. We constrain the rotational
broadening, v sin i < 79 km/s, at the 90% confidence level, which gives a mass
ratio q < 0.053. The K-type companion star of Nova Oph 1977 contributes 28-37%
of the light at red wavelengths. The abnormal LiI 6708 absorption line from the
companion star is not detected (EW < 0.12 A), in contrast to four other X-ray
binaries. An Halpha Doppler image of the system shows emission from the
companion star in addition to the accretion disk.Comment: 14 pages of text and tables plus 3 figures, to appear in the
Astronomical Journa
The emission-line pulse pattern in the intermediate polar RX J0558
We observed the intermediate polar RX J0558+53 with the 4.2m WHT and find in
the pulsed emission lines, a ``corkscrew'' pattern, which indicates a two-pole
white dwarf accretion. The ``corkscrew'' pattern consists of two emission-line
pulses, separated by half the white dwarf spin period, and moving from red to
blue velocities. The detected emission-line pulsations have an amplitude of
1.1--2.7 per cent in the He II and Balmer emission lines on the 545-s spin
period of the white dwarf which compare to 3.5-4.8 per cent for the continuum
double-peak pulsations. We image the emission-line pulse pattern and is shown
to lag the continuum pulse by 0.12 spin cycles. We interpret the pattern by
invoking an accretion curtain from the disrupted, inner disc to the two poles
of the magnetic white dwarf. The semi-amplitude of the He II pulse of 408+-35
km/s can be used to constrain the size of the magnetosphere, R ~ 4.1 x 10^4 km,
and the magnetic moment of the white dwarf (~2.4 10^32 G cm^3). Power spectra
show dominant frequencies at 2 \omega and 2 (\omega-\Omega) which suggest
reprocessing of the white dwarf's illuminating beams in the accretion disc.
Finally, the steady He II emission line shows a strong sinusoidal component
moving from red to blue on the orbital period, with a width similar to that
expected from irradiation of the secondary star. Imaging of the emission lines
indicate illuminated locations at the inner side of the red star and the back
side of the accretion disc.Comment: 12 pages, 11 figures, MNRAS journal paper. in pres
XTE J1118+480: A Metal-Rich Black Hole Binary in the Galactic Halo
We present medium-resolution optical spectra of the secondary star in the
high Galactic latitude black hole X-ray binary XTE J1118+480 and determine the
abundance of Mg, Al, Ca, Fe, and Ni in its atmosphere. For all the elements
investigated we find supersolar abundances; thus, we reject the hypothesis that
the black hole came from the direct collapse of an ancient massive halo star.
The compact primary most likely formed in a supernova event of a massive star
whose nucleosynthetic products polluted the secondary star. The observed
element abundances and their ratios can be explained using a variety of
supernova models with a wide range of metallicities. While an explosive origin
in the Galactic halo or thick disk cannot be discarded, a metal-rich progenitor
is clearly favored by the observed abundance pattern. This suggests that the
black hole was produced in the Galactic thin disk with a violent natal kick,
propelling the X-ray binary to its current location and orbit.Comment: Accepted for publication as a letter in The Astrophysical Journa
Is the plateau state in GRS 1915+105 equivalent to canonical hard states?
GRS1915+105 is a very peculiar black hole binary that exhibits
accretion-related states that are not observed in any other stellar-mass black
hole system. One of these states, however -- referred to as the plateau state
-- may be related to the canonical hard state of black hole X-ray binaries.
Both the plateau and hard state are associated with steady, relatively lower
X-ray emission and flat/inverted radio emission, that is sometimes resolved
into compact, self-absorbed jets. However, while generally black hole binaries
quench their jets when the luminosity becomes too high, GRS1915+105 seems to
sustain them despite the fact that it accretes at near- or super-Eddington
rates. In order to investigate the relationship between the plateau and the
hard state, we fit two multi-wavelength observations using a steady-state
outflow-dominated model, developed for hard state black hole binaries. The data
sets consist of quasi-simultaneous observations in radio, near-infrared and
X-ray bands. Interestingly, we find both significant differences between the
two plateau states, as well as between the best-fit model parameters and those
representative of the hard state. We discuss our interpretation of these
results, and the possible implications for GRS 1915+105's relationship to
canonical black hole candidates.Comment: accepted for publication in MNRA
The emission-line pulse pattern in the intermediate polar RX J0558+53
We observed the intermediate polar RX J0558+53 with the 4.2-m William Herschel Telescope (WHT) and find a 'corkscrew' pattern in the pulsed emission lines, which indicates a two-pole white dwarf accretion. The 'corkscrew' pattern consists of two emission-line pulses, separated by half the white dwarf spin period, and moving from red to blue velocities. The detected emission-line pulsations have an amplitude of 1.1-2.7 per cent in the He II and Balmer emission lines at the 545-s spin period of the white dwarf compared with 3.5-4.8 per cent for the continuum double-peak pulsations. We image the emission-line pulse pattern and it is shown to lag the continuum pulse by 0.12 spin cycles. We interpret the pattern by invoking an accretion curtain from the disrupted, inner disc to the two poles of the magnetic white dwarf. The semi-amplitude of the He II pulse of 408 +/- 35 km s(-1) can be used to constrain the size of the magnetosphere, R similar to 4.1 x 10(4) km, and the magnetic moment of the white dwarf (similar to 2.4 x 10(32) G cm(3)). Power spectra show dominant frequencies at 2 omega and 2(omega - Omega) which suggest reprocessing of the illuminating beams of the white dwarf in the accretion disc. Finally, the steady He II emission line shows a strong sinusoidal component moving from red to blue at binary phase 0.5, with a width similar to that expected from irradiation of the secondary star. Imaging of the emission lines indicates illuminated locations at the inner side of the red star and the back side of the accretion disc.</p
The emission-line pulse pattern in the intermediate polar RX J0558+53
We observed the intermediate polar RX J0558+53 with the 4.2m WHT and find in the pulsed emission lines, a "corkscrew" pattern, which indicates a two-pole white dwarf accretion. The "corkscrew" pattern consists of two emission-line pulses, separated by half the white dwarf spin period, and moving from red to blue velocities. The detected emission-line pulsations have an amplitude of 1.1--2.7 per cent in the He II and Balmer emission lines on the 545-s spin period of the white dwarf which compare to 3.5-4.8 per cent for the continuum double-peak pulsations. We image the emissionline pulse pattern and is shown to lag the continuum pulse by 0.12 spin cycles. We interpret the pattern by invoking an accretion curtain from the disrupted, inner disc to the two poles of the magnetic white dwarf. The semi-amplitude of the He II pulse of 408\Sigma35 km s \Gamma1 can be used to constrain the size of the magnetosphere, R ¸ 4:1 \Theta 10 4 km, and the magnetic moment of the white dwarf (¸ 2:4 \..