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[en] The Hard X-ray Modulation Telescope (HXMT) named Insight is China's first X-ray astronomical satellite, with the Low Energy X-ray Telescope (LE) as one of its main payloads onboard. The detectors of LE adopt swept charge device CCD236 using L-shaped transfer electrodes. To measure the time response distribution resulted from the continuous readout of charges in detection area along specific paths, a long exposure readout mode has been designed. In this mode, CCD236 firstly performs exposure without readout, then all charges generated in preceding exposure phase are read out completely. And an analysis of the photons readout time in this mode is carried out, to obtain the time response distribution.

[en] We demonstrated the Talbot effect using a broadband hard x-ray beam (Δλ/λ ∼1). The exit wave-field of the x-ray beam passing through a grating with a sub micro-meter scale period was successfully replicated and recorded at effective Talbot distance, Z_T. The period was reduced to half at Z_T/4 and 3/4Z_T, and the phase reversal was observed at Z_T/2. The propagating wave-field recorded on photoresists was consistent with a simulated result.

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[en] The macromolecular crystallography beamline MX1 at the Australian Synchrotron is described. MX1 is a bending-magnet crystallography beamline at the 3 GeV Australian Synchrotron. The beamline delivers hard X-rays in the energy range from 8 to 18 keV to a focal spot at the sample position of 120 µm FWHM. The beamline endstation and ancillary equipment facilitate local and remote access for both chemical and biological macromolecular crystallography. Here, the design of the beamline and endstation are discussed. The beamline has enjoyed a full user program for the last seven years and scientific highlights from the user program are also presented

[en] Tidal disruption events (TDEs) taking place in active galactic nuclei (AGNs) are different from ordinary TDEs. In these events, the returning tidal debris stream drills through the preexisting AGN accretion disk near the stream pericenter, destroying the inner disk in the process, and then intersects with the disk a second time at radii ranging from a few times to hundreds of times the pericenter distance. The debris dynamics of such TDEs, and hence their appearance, are distinct from those of ordinary TDEs. Here we explore the observational signatures of this “second impact” of the stream with the disk. Strong shocks form as the dilute stream is stopped by the denser disk. Compton cooling of the shocked material produces hard X-rays and even soft γ-rays, with most of the energy emitted between ∼10 keV and 1 MeV. The luminosity follows the mass-return rate, peaking between ∼10⁴² and 10⁴⁴ erg s⁻¹. The X-ray hardness and the smoothness of the light curve provide possible means for distinguishing the second impact from ordinary AGN flares, which exhibit softer spectra and more irregular light curves.

[en] We report on a systematic search for hard X-ray and γ-ray emission in coincidence with fast radio bursts (FRBs) observed by the AGILE satellite. We used 13 yr of AGILE archival data searching for time coincidences between exposed FRBs and events detectable by the MCAL (0.4–100 MeV) and GRID (50 MeV–30 GeV) detectors at timescales ranging from milliseconds to days/weeks. The current AGILE sky coverage allowed us to extend the search for high-energy emission preceding and following the FRB occurrence. We considered all FRB sources currently included in catalogs and identified a subsample (15 events) for which a good AGILE exposure with either MCAL or GRID was obtained. In this paper we focus on nonrepeating FRBs, compared to a few nearby repeating sources. We did not detect significant MeV or GeV emission from any event. Our hard X-ray upper limits (ULs) in the MeV energy range were obtained for timescales from submillisecond to seconds, and in the GeV range from minutes to weeks around event times. We focus on a subset of five nonrepeating and two repeating FRB sources whose distances are most likely smaller than that of 180916.J0158+65 (150 Mpc). For these sources, our MeV ULs translate into ULs on the isotropically emitted energy of about 3 × 10⁴⁶ erg, comparable to that observed in the 2004 giant flare from the Galactic magnetar SGR 1806–20. On average, these nearby FRBs emit radio pulses of energies significantly larger than the recently detected SGR 1935+2154 and are not yet associated with intense MeV flaring.

[en] We report on high-resolution optical and hard X-ray observations of solar flare ribbons seen during the GOES X6.5 class white-light flare of 2006 December 6. The data consist of imaging observations at 430 nm (the Fraunhofer G band) taken by the Hinode Solar Optical Telescope with the hard X-rays observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager. The two sets of data show closely similar ribbon structures, strongly suggesting that the flare emissions in white light and in hard X-rays have physically linked emission mechanisms. While the source structure along the ribbons is resolved at both wavelengths (length ∼ 30''), only the G-band observations resolve the width of the ribbon, with values between ∼0.''5 and ∼1.''8. The unresolved hard X-ray observations reveal an even narrower ribbon in hard X-rays (the main footpoint has a width perpendicular to the ribbon of <1.''1 compared to the G-band width of ∼1.''8) suggesting that the hard X-ray emission comes from the sharp leading edge of the G-band ribbon. Applying the thick-target beam model, the derived energy deposition rate is >5 x 10¹² erg s^-1 cm^-2 provided by an electron flux of 1 x 10²⁰ electrons s^-1 cm^-2 above 18 keV. This requires that the beam density of electrons above 18 keV be at least 1 x 10¹⁰ cm^-3. Even if field lines converge toward the chromospheric footpoints, the required beam in the corona has too high a density to be described as a dilute tail population on top of a Maxwellian core. We discuss this issue and others associated with this extreme event, which poses serious questions to the standard thick target beam interpretation of solar flares.

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No abstract available