Using the data acquired in the time-to-spill (TTS) mode for long gamma-ray bursts (GRBs) by the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (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 multipeak GRBs. We find that a temporal lead by higher energy -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 to and places constraints on the physical mechanism(s) for 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 a systematic spectral lag-luminosity connection for pulses within a given long GRB.

Abstract. We present the results from a detailed deprojection analysis of Abell 1835 as observed by 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 ∼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 ∼ 1.8 keV) has a much lower metal abundance than the hot component (T ∼ 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 ∼15 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 ∼153 kpc implied by the presence of a gravitational lensing arc, which is about half of the mass determined from the optical lensing.

We performed a Cr-K emission line survey in young supernova remnants (SNRs) with the Chandra archival data. Our sample includes W49B, Cas A, Tycho and Kepler. We confirmed the existence of the Cr line in W49B and discovered this emission line in the other three SNRs. The line center energies, equivalent widths (EWs) and fluxes of the Cr lines are given. The Cr in Cas A is in a high ionization state while that in Tycho and Kepler is in a much lower one. We find a good positive correlation between Cr and Fe line center energies, suggesting a common origin of Cr and Fe in the nucleosynthesis, which is consistent with the theoretical predictions. We propose that the EW ratio between Cr and Fe can be used as a supplementary constraint on the progenitors' properties and the explosion mechanism.

Alpha power attenuation during cognitive task performing has been suggested to reflect a process of release of inhibition, increase of excitability, and thereby benefit the improvement of performance. Here, we hypothesized that changes in individual alpha power during the execution of a complex language comprehension task may correlate with the individual performance in that task. We tested this using magnetoencephalography (MEG) recorded during comprehension of German sentences of different syntactic complexity. Results showed that neither the frequency nor the power of the spontaneous oscillatory activity at rest were associated with the individual performance. However, during the execution of a sentences processing task, the individual alpha power attenuation did correlate with individual language comprehension performance. Source reconstruction localized effects in temporal-parietal regions of both hemispheres. While the effect of increased task difficulty is localized in the right hemisphere, the difference in power attenuation between tasks of different complexity exhibiting a correlation with performance was localized in left temporal-parietal brain regions known to be associated with language processing. From our results, we conclude that in-task attenuation of individual alpha power is related to the essential mechanisms of the underlying cognitive processes, rather than merely to general phenomena like attention or vigilance.

The Hard X-ray Modulation Telescope (Insight-HXMT) was successfully launched on June 15 th , 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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