arXiv subjects

I. Hatsukade

Publications and source records attributed to I. Hatsukade.

4 recordsLinked to original sources

arXiv2025

Chemical composition and enrichment of the Centaurus cluster core seen by XRISM/Resolve

Hot, X-ray emitting atmospheres pervading galaxy clusters are rich in metals, which have been synthesised and released by asymptotic giant branch (AGB) stars, core-collapse supernovae (SNcc) and Type Ia supernovae (SNIa) over cosmic history. This makes the intracluster medium (ICM) an ideal astrophysical system to constrain its chemical composition, hence ultimately understand metal production and enrichment on megaparsec scales. In this work, we take advantage of the unprecedented ~5 eV resolution offered by XRISM/Resolve to measure the chemical composition of the core of the bright, nearby, and metal-rich Centaurus cluster (287 ks) with unprecedented accuracy. We use these measurements to provide constraints on the stellar populations having enriched the cluster core. We derived the Fe abundance and its relative Si/Fe, S/Fe, Ar/Fe, Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe ratios. We completed this high-resolution view with N/Fe, O/Fe, Ne/Fe, and Mg/Fe ratios obtained with XMM-Newton/RGS archival data. Similarly to the core of Perseus, we find that nine out of our 11 measured abundance ratios are formally consistent with the chemical composition of our Solar System. However, the (super-solar) N/Fe and (half-solar) Mg/Fe ratios significantly differ from Perseus and/or other systems, thus provide tension with the picture of a fully solar composition ubiquitous to all systems. In addition, possible uncertainties in O/Fe and Ne/Fe with atomic codes highlight the need for studying more systems at high spectral resolution to assess (or rule out) the universality of the ICM composition in clusters' cool cores. Combinations of (AGB+)SNcc+SNIa yield models can reproduce our observed X/Fe ratios in all cases. However, whether two distinct populations of SNIa are needed depends on the weight of our RGS measurements. We also briefly discuss the possibility of a multi-metallicity gas phase in this respect.

astro-ph.GA↗

arXiv2025

A XRISM/Resolve view of the dynamics in the hot gaseous atmosphere of M87

The XRISM/Resolve microcalorimeter directly measured the gas velocities in the core of the Virgo Cluster, the closest example of AGN feedback in a cluster. This proximity allows us to resolve the kinematic impact of feedback on scales down to 5 kpc. Our spectral analysis reveals a high velocity dispersion of $\sigma_v$=262 (+45 / -38) km/s near the AGN, which steeply declines to ~60 km/s between 5 and 25 kpc in the northwest direction. The observed line-of-sight bulk velocity in all regions is broadly consistent with the central galaxy, M87, with a mild trend toward blueshifted motions at larger radii. Systematic uncertainties have been carefully assessed and do not affect the measurements. The central velocities, if attributed entirely to isotropic turbulence, correspond to a transonic ICM at sub-6 kpc scales with three-dimensional Mach number 0.69 (+0.14 / -0.11) and a non-thermal pressure fraction of 21 (+7 / -5)%. Simple models of weak shocks and sound waves and calculations assuming isotropic turbulence both support the hypothesis that the velocity field reflects a mix of shock-driven expansion and turbulence. Compared to other clusters observed by XRISM to date, M87's central region stands out as the most kinematically disturbed, exhibiting both the highest velocity dispersion and the largest 3D Mach number, concentrated at the smallest physical scales.

astro-ph.GA↗

arXiv2017

In-orbit performance of the soft X-ray imaging system aboard Hitomi (ASTRO-H)

We describe the in-orbit performance of the soft X-ray imaging system consisting of the Soft X-ray Telescope and the Soft X-ray Imager aboard Hitomi. Verification and calibration of imaging and spectroscopic performance are carried out making the best use of the limited data of less than three weeks. Basic performance including a large field of view of 38'x38' is verified with the first light image of the Perseus cluster of galaxies. Amongst the small number of observed targets, the on-minus-off pulse image for the out-of-time events of the Crab pulsar enables us to measure a half power diameter of the telescope as about 1.3'. The average energy resolution measured with the onboard calibration source events at 5.89 keV is 179 pm 3 eV in full width at half maximum. Light leak and cross talk issues affected the effective exposure time and the effective area, respectively, because all the observations were performed before optimizing an observation schedule and parameters for the dark level calculation. Screening the data affected by these two issues, we measure the background level to be 5.6x10^{-6} counts s^{-1} arcmin^{-2} cm^{-2} in the energy band of 5-12 keV, which is seven times lower than that of the Suzaku XIS-BI.

astro-ph.IM↗

arXiv2003

Design and Performance of the Wide-Field X-Ray Monitor on Board the High-Energy Transient Explorer 2

The Wide-field X-ray Monitor (WXM) is one of the scientific instruments carried on the High Energy Transient Explorer 2 (HETE-2) satellite launched on 2000 October 9. HETE-2 is an international mission consisting of a small satellite dedicated to provide broad-band observations and accurate localizations of gamma-ray bursts (GRBs). A unique feature of this mission is its capability to determine and transmit GRB coordinates in almost real-time through the burst alert network. The WXM consists of three elements: four identical Xe-filled one-dimensional position-sensitive proportional counters, two sets of one-dimensional coded apertures, and the main electronics. The WXM counters are sensitive to X-rays between 2 keV and 25 keV within a field-of-view of about 1.5 sr, with a total detector area of about 350 cm$^2$. The in-flight triggering and localization capability can produce a real-time GRB location of several to 30 arcmin accuracy, with a limiting sensitivity of $10^{-7}$ erg cm$^{-2}$. In this report, the details of the mechanical structure, electronics, on-board software, ground and in-flight calibration, and in-flight performance of the WXM are discussed.

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