arXiv subjects

Marie Kondo

Publications and source records attributed to Marie Kondo.

7 recordsLinked to original sources

arXiv2026

XRISM Reveals a Kinematically Coherent Core System of the Nearby Cool-Core Cluster Abell 2199

We present the results of a deep 251 ks XRISM/Resolve observation of the cool core of the galaxy cluster Abell 2199. From the integrated spectrum of the central $3' \times 3'$ Resolve field of view ($104 \times 104 \mathrm{~kpc}^2$), we find that the intracluster medium (ICM) redshift is consistent with that of the brightest cluster galaxy, within the optical-redshift uncertainty. This indicates that they form a kinematically coherent core system, which offset from the mean cluster redshift by $\sim200~\mathrm{km~s^{-1}}$. The observed velocity dispersion of $\sim100~\mathrm{km~s^{-1}}$ corresponds to a three-dimensional Mach number of $M_{\mathrm{3D}}=0.16$ and a non-thermal pressure fraction of $P_{\mathrm{NT}}/P_{\mathrm{tot}}=1.4\pm0.2$%. Abell 2199 is one of the most dynamically quiescent relaxed clusters observed with XRISM, despite the presence of radio jets and a plume-like structure possibly associated with sloshing motions. Order-of-magnitude estimates suggest that turbulent dissipation could offset a non-negligible fraction of the radiative cooling losses, with $Q_{\mathrm{turb}}/Q_{\mathrm{cool}}\approx0.2$ for a large-scale driver such as sloshing and larger values for smaller AGN-feedback scales. Finally, we detect a localized enhancement of the Fe XXV He$\alpha$ $y$ line in the southeast region, which spatially coincides with a Chandra surface brightness discontinuity.

astro-ph.GA↗

arXiv2026

X-ray line diagnostics of the multi-phase gas in the Centaurus cluster core with XRISM/Resolve

We report the multi-temperature structure of the intracluster medium (ICM) in the Centaurus cluster core observed with XRISM/Resolve. Thanks to its high energy resolution, Resolve enables us to measure fine structures of highly ionized emission lines from Si to Fe and to directly determine the excitation temperature and the ionization temperature from the emission line ratio diagnostics. The observed spectrum in the Centaurus core is well-represented by a double-temperature thermal plasma at collisional ionization equilibrium state rather than an isothermal one. The line ratio diagnostics also support this biphasic temperature structure. Particularly, the observed line ratios show a trend of increasing ionization temperature with atomic mass, while the ionization and excitation temperatures of Fe show nearly the same temperature. The resultant line ratios, which are well-represented by the two temperatures ICM, ~ 1.6 and ~ 3 keV, are also fairly consistent with the expected numbers when assuming the radial single-temperature ICM was projected in the cluster core along the line of sight. Due to the limited low-energy sensitivity of the Resolve with the gate valve closed, we investigated the effect of the cool component using the XMM-Newton/RGS spectrum, but it ultimately did not affect our results. The observed flux ratio between the Fe XXV He alpha resonance and forbidden lines shows an about 20% reduction, suggesting the presence of resonant scattering.

astro-ph.HE↗

arXiv2026

XMM-Newton observations of ten high-redshift CAMIRA clusters of galaxies

We present results from XMM-Newton observations of ten high-redshift ($0.81 < z < 1.17$) galaxy clusters selected from the CAMIRA catalog based on high richness ($N > 40$). These massive clusters, identified in the Hyper Suprime-Cam Subaru Strategic Program field, provide an ideal sample for probing the dynamical state of the intracluster medium (ICM) in the early Universe. We performed uniform X-ray imaging and spectral analyses to measure the ICM temperature and bolometric luminosity, and investigated cluster morphology through offsets between the brightest cluster galaxy (BCG) and the X-ray peak. Extended X-ray emission was detected from all targets, but only one system was classified as dynamically relaxed, indicating a low relaxed fraction ($\sim 10\%$) at high redshift. By combining this high-$z$ sample with a lower-redshift CAMIRA cluster sample, we derived scaling relations among richness, temperature, luminosity, and mass. The results are broadly consistent with predictions from both the self-similar model and the baseline model incorporating the mass--concentration relation. We find no significant redshift evolution, strengthening the view that cluster scaling relations are largely established by $z \sim 1$. We also examined the AGN fraction among member galaxies and found significantly higher AGN activity in high-redshift clusters, particularly in the outskirts, suggesting enhanced AGN triggering during early cluster assembly and a possible connection to the thermodynamic state of dynamically young clusters. These findings provide new insights into the formation and evolution of massive clusters and the thermodynamic history of the ICM, and complement large-area X-ray surveys such as eROSITA.

astro-ph.CO↗

arXiv2026

Chemical enrichment in the Ophiuchus cluster core studied by high-resolution XRISM spectroscopy

Galaxy clusters provide an ideal laboratory for investigating the chemical enrichment history of the universe because they host the hot intracluster medium (ICM), which contains various chemical elements. The X-ray observations have constituted a unique way to measure the element abundance and composition of the ICM due to their prominent emission lines in the 0.1-10 keV range. We explore the metal abundances and chemical enrichment in the cool-core galaxy cluster, Ophiuchus, by using a 217 ks XRISM data set. The abundances of Si, S, Ar, Ca, Cr, Mn, Fe, and Ni are accurately determined using high-resolution spectroscopy. We find that the average uncertainties of chemical composition, which are reported as X/Fe ratios, are only 10-20%. The X/Fe abundance pattern of the Ophiuchus centre is remarkably consistent with solar, which is reminiscent of the Hitomi constraint on the Perseus core. The observed abundance pattern can be replicated globally by linear combination models of core-collapse, including massive progenitors, and Type Ia supernovae. While nucleosynthesis models typically underestimate the Ca/Fe ratio, a substantial contribution of Ca-rich gap transients may help improve the deficit of Ca. High-resolution spectroscopic data can enable us to estimate the underlying impact on the chemical enrichment from subclasses of Type Ia supernovae.

astro-ph.GA↗

arXiv2025

Suzaku observations of outskirts of nearby clusters and groups: I. electron density and gas fraction to the virial radius

We present an analysis of Suzaku observations of 14 nearby galaxy clusters and groups (z < 0.06), extending radial coverage out to the virial radius (approximately r200). The sample spans a wide mass range, from M500 about 2x10^13 to 7x10^14 solar masses, and includes well-studied systems such as Coma, Perseus, and Virgo. We carefully modeled all background components, including the soft X-ray foregrounds (the Local Hot Bubble, Milky Way Halo, and super-virial temperature components), the cosmic X-ray background, and the non-X-ray background, and assessed their effects on the derived properties of the intracluster medium (ICM). We constructed radial profiles of emission measure, electron density, and temperature. Temperatures decrease smoothly with radius, typically dropping to about one-third to half of their peak values near r200. For relaxed clusters, the emission measure profiles outside the core regions are well described by a beta model with beta around 0.6-0.7, while groups show slightly flatter slopes of beta around 0.4-0.65. Beyond r2500, electron density profiles follow a power-law decline with a slope close to 2. At r500 and r200, the electron density and the gas mass fraction show a tight correlation with the system mass, except for three clusters with bright subclusters. In massive clusters, the gas fraction increases with radius and approaches the cosmic baryon fraction near r200. In contrast, lower-mass systems exhibit gas fractions of around 0.1 at r200. The observed mass dependence of gas fractions suggests that feedback and related processes play an increasingly important role toward the group scale, shaping the connection between baryons and dark matter halos.

astro-ph.GA↗

arXiv2025

XRISM Observation of the Ophiuchus Galaxy Cluster: Quiescent Velocity Structure in the Dynamically Disturbed Core

We present the high-resolution X-rayspectroscopic observations of the Ophiuchus galaxy cluster core using the XRISM satellite. Despite previous observations revealing multiple cold fronts and dynamical disturbances in the cluster core, our XRISM observations show low gas velocity dispersions of sigma_v = 115 +/- 7 km s^-1 in the inner region (~< 25 kpc) and sigma_v = 186 +/- 9 km s^-1 in the outer region (~ 25-50 kpc). The gas temperatures are kT = 5.8 +/- 0.2 keV and 8.4 +/- 0.2 keV for the inner and outer regions, respectively, with metal abundances of Z = 0.75 +/- 0.03 Z_sun (inner) and 0.44 +/- 0.02 Z_sun (outer). The measured velocity dispersions correspond to nonthermal pressure fractions of only 1.4 +/- 0.2% (inner) and 2.5 +/- 0.2% (outer), indicating highly subsonic turbulence. Our analysis of the bulk gas motion indicates that the gas in the inner region is nearly at rest relative to the central galaxy (|v_bulk| = 8 +/- 7 km s^-1), while the outer region exhibits a moderate motion of |v_bulk| = 104 +/- 7 km s^-1. Assuming the velocity dispersion arises from turbulent motions, the turbulent heating rate is ~ 40\% of the radiative cooling rate, although there is some uncertainty. This suggests that the heating and cooling of the gas are not currently balanced. The activity of the central active galactic nucleus (AGN) has apparently weakened. The sloshing motion that created the cold fronts may now be approaching a turning point at which the velocity is minimum. Alternatively, the central galaxy and the associated hot gas could be moving nearly parallel to the plane of the sky.

astro-ph.HE↗

arXiv2024

AGN properties of ~1 million member galaxies of galaxy groups and clusters at z < 1.4 based on the Subaru Hyper Suprime-Cam survey

Herein, we present the statistical properties of active galactic nuclei (AGNs) for approximately 1 million member galaxies of galaxy groups and clusters, with 0.1 $<$ cluster redshift ($z_{\rm cl}$) $<$ 1.4, selected using Subaru Hyper Suprime-Cam, the so-called CAMIRA clusters. In this research, we focused on the AGN power fraction ($f_{\rm AGN}$), which is defined as the proportion of the contribution of AGNs to the total infrared (IR) luminosity, $L_{\rm IR}$ (AGN)/$L_{\rm IR}$, and examined how $f_{\rm AGN}$ depends on (i) $z_{\rm cl}$ and (ii) the distance from the cluster center. We compiled multiwavelength data using the ultraviolet--mid-IR range. Moreover, we performed spectral energy distribution fits to determine $f_{\rm AGN}$ using the CIGALE code with the SKIRTOR AGN model. We found that (i) the value of $f_{\rm AGN}$ in the CAMIRA clusters is positively correlated with $z_{\rm cl}$, with the correlation slope being steeper than that for field galaxies, and (ii) $f_{\rm AGN}$ exhibits a high value at the cluster outskirts. These results indicate that the emergence of AGN population depends on the redshift and environment and that galaxy groups and clusters at high redshifts are important in AGN evolution. Additionally, we demonstrated that cluster--cluster mergers may enhance AGN activity at the outskirts of particularly massive galaxy clusters. Our findings are consistent with a related study on the CAMIRA clusters that was based on the AGN number fraction.

astro-ph.GA↗