arXiv subjects

S. M. Jia

Publications and source records attributed to S. M. Jia.

50 records · Page 3Linked to original sources

arXiv2019

Insight-HXMT observation on 4U~1608--52: evolving spectral properties of a bright type-I X-ray burst

The evidences for the influence of thermonuclear (type-I) X-ray bursts upon the surrounding environments in neutron star low-mass X-ray binaries (LMXB) were detected previously via spectral and timing analyses. Benefitting from a broad energy coverage of Insight-HXMT, we analyze one photospheric radius expansion (PRE) burst, and find an emission excess at soft X-rays. Our spectral analysis shows that, such an excess is not likely relevant to the disk reflection induced by the burst emission and can be attributed to an enhanced pre-burst/persistent emission. We find that the burst and enhanced persistent emissions sum up to exceed Eddington luminosity by $\sim$ 40 percentages. We speculate that the enhanced emission is from a region beyond the PRE radius, or through the Comptonization of the corona.

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arXiv2019

$Insight$-HXMT study of the timing properties of Sco X-1

We present a detailed timing study of the brightest persistent X-ray source Sco X-1 using the data collected by the Hard X-ray Modulation Telescope ($Insight$-HXMT) from July 2017 to August 2018. A complete $Z$-track hardness-intensity diagram (HID) is obtained. The normal branch oscillations (NBOs) at $\sim$ 6 Hz in the lower part of the normal branch (NB) and the flare branch oscillations (FBOs) at $\sim$ 16 Hz in the beginning part of the flaring branch (FB) are found in observations with the Low Energy X-ray Telescope (LE) and the Medium Energy X-ray Telescope (ME) of $Insight$-HXMT, while the horizontal branch oscillations (HBOs) at $\sim$ 40 Hz and the kilohertz quasi-periodic oscillations (kHz QPOs) at $\sim$ 800 Hz are found simultaneously up to 60 keV for the first time on the horizontal branch (HB) by the High Energy X-ray Telescope (HE) and ME. We find that for all types of the observed QPOs, the centroid frequencies are independent of energy, while the root mean square (rms) increases with energy; the centroid frequencies of both the HBOs and kHz QPOs increase along the $Z$-track from the top to the bottom of the HB; and the NBOs show soft phase lags increasing with energy. A continuous QPO transition from the FB to NB in $\sim$ 200 s are also detected. Our results indicate that the non-thermal emission is the origin of all types of QPOs, the innermost region of the accretion disk is non-thermal in nature, and the corona is nonhomogeneous geometrically.

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arXiv2019

$Insight$-HXMT Science Operations

The Hard X-ray Modulation Telescope ($Insight$-HXMT) was successfully launched on June 15th, 2017. It performs broad band X-ray scan survey of the Galactic Plane to detect new black holes and other objects in active states. It also observes X-ray binaries to study their X-ray variabilities. Here we will introduce the Science Operations of $Insight$-HXMT, which is responsible for collecting and evaluating observation proposals, scheduling observations, and monitoring the working status of the payloads.

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arXiv2019

Insight-HXMT observations of 4U~1636-536: Corona cooling revealed with single short type-I X-ray burst

Corona cooling was detected previously from stacking a series of short type-I bursts occurred during the low/had state of atoll outburst. Type-I bursts are hence regarded as sharp probe to our better understanding on the basic property of the corona. The launch of the first Chinese X-ray satellite Insight-HXMT has large detection area at hard X-rays which provide almost unique chance to move further in this research field. We report the first detection of the corona cooling by Insight-HXMT from single short type-I burst showing up during {\bf flare} of 4U 1636-536. This type-I X-ray burst has a duration of $\sim$13 seconds and hard X-ray shortage is detected with significance 6.2~$σ$ in 40-70 keV. A cross-correlation analysis between the lightcurves of soft and hard X-ray band, shows that the corona shortage lag the burst emission by 1.6 $\pm$1.2~s. These results are consistent with those derived previously from stacking a large amount of bursts detected by RXTE/PCA within a series of {\bf flares} of 4U 1636-536. Moreover, the broad bandwidth of Insight-HXMT allows as well for the first time to infer the burst influence upon the continuum spectrum via performing the spectral fitting of the burst, which ends up with the finding that hard X-ray shortage appears at around 40 keV in the continuum spectrum. These results suggest that the evolution of the corona along with the outburst{\bf /flare} of NS XRB may be traced via looking into a series of embedded type-I bursts by using Insight-HXMT.

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arXiv2019

The Insight-HXMT mission and its recent progresses

The Hard X-ray Modulation Telescope HXMT or also dubbed as Insight HXMT is China s first astronomical satellite . It was launched on 15 th June 2017 in JiuQuan, China and is currently in service smoothly. It was designed to perform point ing , scan ning 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 introduce the mission and its progresses in aspects of payload, core sciences, ground calibration/facility , ground segment, data archive, software, in orbit performance, calibration, background model, observations and preliminary results .

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arXiv2019

Timing analysis of 2S 1417-624 observed with NICER and Insight-HXMT

We present a study of timing properties of the accreting pulsar 2S 1417-624 observed during its 2018 outburst, based on Swift/BAT, Fermi/GBM, Insight-HXMT and NICER observations. We report a dramatic change of the pulse profiles with luminosity. The morphology of the profile in the range 0.2-10.0keV switches from double to triple peaks at $\sim2.5$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$ and from triple to quadruple peaks at $\sim7$ $\rm \times 10^{37}{\it D}_{10}^2\ erg\ s^{-1}$. The profile at high energies (25-100keV) shows significant evolutions as well. We explain this phenomenon according to existing theoretical models. We argue that the first change is related to the transition from the sub to the super-critical accretion regime, while the second to the transition of the accretion disc from the gas-dominated to the radiation pressure-dominated state. Considering the spin-up as well due to the accretion torque, this interpretation allows to estimate the magnetic field self-consistently at $\sim7\times 10^{12}$G.

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arXiv2019

Constant cyclotron line energy in Hercules X-1 -- Joint Insight-HXMT and NuSTAR observations

The long-term evolution of the centroid energy of the CRSF in Her X-1 is still a mystery. We report a new measurement from a campaign between {\sl Insight}-HXMT and {\sl NuSTAR} performed in February 2018. Generally, the two satellites show well consistent results of timing and spectral properties. The joint spectral analysis confirms that the previously observed long decay phase has ended, and that the line energy instead keeps constant around 37.5 keV after flux correction.

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arXiv2019

Hot disk of the Swift J0243.6+6124 revealed by Insight-HXMT

We report on analysis of observations of the bright transient X-ray pulsar \src obtained during its 2017-2018 giant outburst with Insight-HXMT, \emph{NuSTAR}, and \textit{Swift} observatories. We focus on the discovery of a sharp state transition of the timing and spectral properties of the source at super-Eddington accretion rates, which we associate with the transition of the accretion disk to a radiation pressure dominated (RPD) state, the first ever directly observed for magnetized neutron star. This transition occurs at slightly higher luminosity compared to already reported transition of the source from sub- to super-critical accretion regime associate with onset of an accretion column. We argue that this scenario can only be realized for comparatively weakly magnetized neutron star, not dissimilar to other ultra-luminous X-ray pulsars (ULPs), which accrete at similar rates. Further evidence for this conclusion is provided by the non-detection of the transition to the propeller state in quiescence which strongly implies compact magnetosphere and thus rules out magnetar-like fields.

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arXiv2019

In-orbit demonstration of X-ray pulsar navigation with the Insight-HXMT satellite

In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which was launched on Jun. 15th, 2017. The new pulsar navigation method 'Significance Enhancement of Pulse-profile with Orbit-dynamics' (SEPO) is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from Aug. 31th to Sept. 5th in 2017. Using the 5-day-long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard - High Energy X-ray Telescope (HE), Medium Energy X-ray Telescope (ME) and Low Energy X-ray Telescope (LE) - respectively. Combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3 sigma) and 10 m/s (3 sigma), respectively.

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arXiv2018

Insight-HXMT observations of the New Black Hole Candidate MAXI J1535-571: timing analysis

We present the X-ray timing results of the new black hole candidate (BHC) MAXI J1535-571 during its 2017 outburst from Hard X-ray Modulation Telescope (\emph{Insight}-HXMT) observations taken from 2017 September 6 to 23. Following the definitions given by \citet{Belloni2010}, we find that the source exhibits state transitions from Low/Hard state (LHS) to Hard Intermediate state (HIMS) and eventually to Soft Intermediate state (SIMS). Quasi-periodic oscillations (QPOs) are found in the intermediate states, which suggest different types of QPOs. With the large effective area of \emph{Insight}-HXMT at high energies, we are able to present the energy dependence of the QPO amplitude and centroid frequency up to 100 keV which is rarely explored by previous satellites. We also find that the phase lag at the type-C QPOs centroid frequency is negative (soft lags) and strongly correlated with the centroid frequency. By assuming a geometrical origin of type-C QPOs, the source is consistent with being a high inclination system.

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arXiv2009

Deprojection technique for galaxy cluster considering point spread function

We present a new method for the analysis of Abell 1835 observed by XMM-Newton. The method is a combination of the Direct Demodulation technique and deprojection. We eliminate the effects of the point spread function (PSF) with the Direct Demodulation technique. We then use a traditional depro-jection technique to study the properties of Abell 1835. Compared to that of deprojection method only, the central electron density derived from this method increases by 30%, while the temperature profile is similar.

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arXiv2008

XMM-Newton studies of a massive cluster of galaxies: RXCJ2228.6+2036

We present the X-ray properties of a massive cluster of galaxies (RXCJ2228.6+2036 at $z=0.421$) using {\it XMM-Newton} data. The X-ray mass modeling is based on the temperature and density distributions of the intracluster medium derived using a deprojection method. We found that RXCJ2228.6+2036 is a hot cluster ($T_{500}=8.92^{+1.78}_{-1.32}$ keV) showing a cooling flow rate of $12.0^{+56.0}_{-12.0}$ M$_{\odot}$yr$^{-1}$ based on spectral fitting within the cooling flow radius ($r_{cool}=147\pm10$ kpc). The total cluster mass is $M_{500}=(1.19\pm0.35)\times10^{15}$ M$_{\odot}$ and the mean gas mass fraction is $f_{gas}=0.165\pm0.045$ at $r_{500}=1.61\pm0.16$ Mpc. We discussed the PSF-correction effect on the spectral analysis and found that for the annular width we chose the PSF-corrected temperatures are consistent with those without PSF-correction. We observed a remarkable agreement between X-ray and SZ results, which is of prime importance for the future SZ survey. RXCJ2228.6+2036 obeys the empirical scaling relations found in general massive galaxy clusters (e.g. $S$--$T$, $M$--$T$, $L$--$T$ and $M$--$Y$) after accounting for self-similar evolution.

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arXiv2004

Distribution of Spectral Lags in Gamma Ray Bursts

Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy bands of individual pulses contained in 64 multi-peak GRBs. We find that the temporal lead by higher-energy gamma-ray photons (i.e., positive lags) is the norm in this selected sample set of long GRBs. While relatively few in number, some pulses of several long GRBs do show negative lags. This distribution of spectral lags in long GRBs is in contrast to that in short GRBs. This apparent difference poses challenges and constraints on the physical mechanism(s) of producing long and short GRBs. The relation between the pulse peak count rates and the spectral lags is also examined. Observationally, there seems to be no clear evidence for systematic spectral lag-luminosity connection for pulses within a given long GRB.

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arXiv2004

The analysis of Abell 1835 using a deprojection technique

We present the results from a detailed deprojection analysis of Abell 1835 as observed by {\it XMM-Newton}. If we fit the spectra with an isothermal plasma model, the deprojected temperature profile is flat in the outer region around 7.6 keV and decreases to $\sim$ 5.6 keV in the center, which may be connected with the gas cooling. In the central part, a two-component thermal plasma model can fit the spectrum significantly better. Moreover, the cool component (T $\sim$ 1.8 keV) has a much lower metal abundance than the hot component (T $\sim$ 8 keV), which may be due to the longer cooling time for the cool gas with lower abundance. In addition, it was found that without a main isothermal component, the standard cooling flow model cannot fit the spectrum satisfactorily. From the isothermal model fitting results we also derived the electron density $n_e$, and fitted its radial distribution with a double-$β$ model. The $n_e$ profile inferred with the double-$β$ model and the deprojected X-ray gas temperature profile were then combined to derive the total mass and the total projected mass of the cluster. The projected mass is lower than that derived from the weak lensing method. However, assuming that the cluster extends to a larger radius $\sim15'$ as found by Clowe & Schneider (2002), the two results are consistent within the error bars. Furthermore, we calculated the projected mass within the radius of $\sim$ 153 kpc implied by the presence of a gravitational lensing arc, which is about half of the mass determined from the optical lensing.

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