30 research outputs found
Measuring the black hole masses in accreting X-ray binaries by detecting the Doppler orbital motion of their accretion disk wind absorption lines
So far essentially all black hole masses in X-ray binaries have been obtained
by observing the companion star's velocity and light curves as functions of the
orbital phase. However a major uncertainty is the estimate of the orbital
inclination angle of an X-ray binary. Here we suggest to measure the black hole
mass in an X-ray binary by measuring directly the black hole's orbital motion,
thus obtaining the companion to black hole mass ratio. In this method we assume
that accretion disk wind moves with the black hole and thus the black hole's
orbital motion can be obtained from the Doppler velocity of the absorption
lines produced in the accretion disk wind. We validate this method by analyzing
the Chandra/HETG observations of GRO J1655-40, in which the black hole orbital
motion with line of sight velocity of 90.8 (+-11.3) km/s, inferred from the
Doppler velocity of disk-wind absorption lines, is consistent with the
prediction from its previously measured system parameters. We obtain the black
hole mass of 5.41 (+0.98, -0.57) solar masses and system inclination of 72.0
(+7.8, -7.5) degrees in GRO J1655-40. Additional observations of this source
covering more orbital phases can improve estimates on its system parameters
substantially. We then apply the method to the black hole X-ray binary LMC X-3
observed with HST/COS near orbital phase 0.75. We find that the disk-wind
absorption lines of CIV doublet were shifted to about 50 km/s, which yields a
companion-to-black-hole mass ratio of 0.6 for an assumed disk wind velocity of
-400 km/s. Additional observations covering other orbital phases (0.25 in
particular) are crucial to ease this assumption and then to directly constrain
the mass ratio. This method in principle can also be applied to any accreting
compact objects with detectable accretion disk wind absorption line features.Comment: 8 pages, 4 figures, 1 table. Accepted for publication in MNRA
Insight-HXMT on-orbit thermal control status and thermal deformation impact analysis
Purpose: The Hard X-ray Modulation Telescope is China's first X-ray astronomy
satellite launched on June 15th, 2017, dubbed Insight-HXMT. Active and passive
thermal control measures are employed to keep devices at suitable temperatures.
In this paper, we analyzed the on-orbit thermal monitoring data of the first 5
years and investigated the effect of thermal deformation on the point spread
function (PSF) of the telescopes.
Methods: We examined the data of the on-orbit temperatures measured using 157
thermistors placed on the collimators, detectors and their support structures
and compared the results with the thermal control requirements. The thermal
deformation was evaluated by the relative orientation of the two star sensors
installed on the main support structure. its effect was estimated with
evolution of the PSF obtained with calibration scanning observations of the
Crab nebula.
Conclusion: The on-orbit temperatures met the thermal control requirements
thus far, and the effect of thermal deformation on the PSF was negligible after
the on-orbit pointing calibration.Comment: 25 pages, 35 figures, submitte
Insight-HXMT observations of Swift J0243.6+6124 during its 2017-2018 outburst
The recently discovered neutron star transient Swift J0243.6+6124 has been
monitored by {\it the Hard X-ray Modulation Telescope} ({\it Insight-\rm HXMT).
Based on the obtained data, we investigate the broadband spectrum of the source
throughout the outburst. We estimate the broadband flux of the source and
search for possible cyclotron line in the broadband spectrum. No evidence of
line-like features is, however, found up to . In the absence of
any cyclotron line in its energy spectrum, we estimate the magnetic field of
the source based on the observed spin evolution of the neutron star by applying
two accretion torque models. In both cases, we get consistent results with
, and peak luminosity of which makes the source the first Galactic ultraluminous
X-ray source hosting a neutron star.Comment: publishe
Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite
As China's first X-ray astronomical satellite, the Hard X-ray Modulation
Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15,
2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy
satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was
designed to perform pointing, scanning and gamma-ray burst (GRB) observations
and, based on the Direct Demodulation Method (DDM), the image of the scanned
sky region can be reconstructed. Here we give an overview of the mission and
its progresses, including payload, core sciences, ground calibration/facility,
ground segment, data archive, software, in-orbit performance, calibration,
background model, observations and some preliminary results.Comment: 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech.
Astron. arXiv admin note: text overlap with arXiv:1910.0443
Effects of feeding strategies on growth,body composition, intestine digestive enzymes activities and intestine histology of Megalobrama pellegrini (Tchang, 1930) early juveniles raised in flow-through system
To determine the effects of feeding rate and feeding frequency on growth performance, digestive enzymes activities, and intestine development of Megalobrama pellegrini in a replicated flow-through system, we conducted a 42-day experiment. We designed three feeding rates (5%, 6.5%, and 8% body weight/day, BW/d) and two feeding frequencies (2 and 3 meals/day; m/d) in this experiment. Fish (0.57 ± 0.01 g) were distributed into 18 tanks with 70 individuals and fed with a commercial diet (33% crude protein, 4% total lipid). Results showed that the highest weight gain was found in the fish fed diet with 6.5% BW/day and 3 m/d, which was significantly higher in comparison with that of other feeding rate groups (5% BW/d and 6.5% BW/d) at both feeding frequency (2 and 3 m/d). Fish growth performance was significantly affected by the feeding rate but not by the feeding frequency. The significantly higher feed conversion ratio (FCR) was recorded at 8% BW/d with 3 m/d than other treatments. Furthermore, fish fed diet at 8% BW/d with 2 m/d had significantly high mortality during the middle of this trial. In contrast, we found that other fish groups' survival rates were higher (over 90%), and there were no significant differences among them. We saw a significantly lower whole-body crude protein, lipid, and intestinal digestive enzymes in fish fed at a ratio of 8% BW/d with 3 m/d compared with other treatments. Moreover, our findings revealed intestinal villi fusion and exfoliation in this group compared with other treatments. In conclusion, the Megalobrama pellegrini received a feeding rate of 6.5% BW/d, and a feeding frequency of 2 m/d may be the optimum feeding regime for raising Megalobrama pellegrini in a flow-through system
Dilation framing camera with 4 ps resolution
A framing camera using pulse-dilation technology is reported in this article. The camera uses pulse dilation of an electron signal from a pulsed photo-cathode (PC) to achieve high temporal resolution. While the PC is not pulsed, the measured temporal resolution of the camera without pulse-dilation is about 71 ps. While the excitation pulse is applied on the PC, the measured temporal resolution is improved to 4 ps by using the pulse-dilation technology. The spatial resolution of the dilation framing camera is also measured, which is better than 100 μm. The relationship between the temporal resolution and the PC bias voltage is obtained. The variation of the temporal resolution with the gradient of the PC excitation pulse is also provided