arXiv subjects

XRISM collaboration

Publications and source records attributed to XRISM collaboration.

6 recordsLinked to original sources

arXiv2025

Chlorine and Potassium Enrichment in the Cassiopeia A Supernova Remnant

The elements in the universe are synthesized primarily in stars and supernovae, where nuclear fusion favors the production of even-Z elements. In contrast, odd-Z elements are less abundant and their yields are highly dependent on detailed stellar physics, making theoretical predictions of their cosmic abundance uncertain. In particular, the origin of odd-Z elements such as phosphorus (P), chlorine (Cl), and potassium (K), which are important for planet formation and life, is poorly understood. While the abundances of these elements in Milky Way stars are close to solar values, supernova explosion models systematically underestimate their production by up to an order of magnitude, indicating that key mechanisms for odd-Z nucleosynthesis are currently missing from theoretical models. Here we report the observation of P, Cl, and K in the supernova remnant Cassiopeia A using high-resolution X-ray spectroscopy with XRISM, with the detection of K at above the 6$\sigma$ level being the most significant finding. Supernova explosion models of normal massive stars cannot explain the element abundance pattern, especially the high abundances of Cl and K, while models that include stellar rotation, binary interactions or shell mergers agree closely with the observations. Our observations suggest that such stellar activity plays a significant role in supplying these elements to the universe.

astro-ph.HE↗

arXiv2025

Stratified wind from a super-Eddington X-ray binary is slower than expected

Accretion discs in strong gravity ubiquitously produce winds, seen as blueshifted absorption lines in the X-ray band of both stellar mass X-ray binaries (black holes and neutron stars), and supermassive black holes. Some of the most powerful winds (termed Eddington winds) are expected to arise from systems where radiation pressure is sufficient to unbind material from the inner disc ($L\gtrsim L_{\rm Edd}$). These winds should be extremely fast and carry a large amount of kinetic power, which, when associated with supermassive black holes, would make them a prime contender for the feedback mechanism linking the growth of those black holes with their host galaxies. Here we show the XRISM Resolve spectrum of the Galactic neutron star X-ray binary, GX 13+1, which reveals one of the densest winds ever seen in absorption lines. This Compton-thick wind significantly attenuates the flux, making it appear faint, although it is intrinsically more luminous than usual ($L\gtrsim L_{\rm Edd}$). However, the wind is extremely slow, more consistent with the predictions of thermal-radiative winds launched by X-ray irradiation of the outer disc, than with the expected Eddington wind driven by radiation pressure from the inner disc. This puts new constraints on the origin of winds from bright accretion flows in binaries, but also highlights the very different origin required for the ultrafast ($v\sim 0.3c$) winds seen in recent Resolve observations of a supermassive black hole at similarly high Eddington ratio.

astro-ph.HE↗

arXiv2025

Delving into the depths of NGC 3783 with XRISM II. Cross-calibration of X-ray instruments used in the large, multi-mission observational campaign

Accurate X-ray spectroscopic measurements are fundamental for deriving basic physical parameters of the most abundant baryon components in the Universe. The plethora of X-ray observatories currently operational enables a panchromatic view of the high-energy emission of celestial sources. However, uncertainties in the energy-dependent calibration of the instrument transfer functions (e.g. the effective area, energy redistribution, or gain) can limit - and historically, did limit - the accuracy of X-ray spectroscopic measurements. We revised the status of the cross-calibration among the scientific payload on board four operation missions: Chandra, NuSTAR, XMM-Newton, and the recently launched XRISM. XRISM carries the micro-calorimeter Resolve, which yields the best energy resolution at energies above 2 keV. For this purpose, we used the data from a 10-day-long observational campaign targeting the nearby active galactic nucleus NGC 3783, carried out in July 2024. We present a novel model-independent method for assessing the cross-calibration status that is based on a multi-node spline of the spectra with the highest-resolving power (XRISM/Resolve in our campaign). We also estimated the impact of the intrinsic variability of NGC 3783 on the cross-calibration status due to the different time coverages of participating observatories and performed an empirical reassessment of the Resolve throughput at low energies. Based on this analysis, we derived a set of energy-dependent correction factors of the observed responses, enabling a statistically robust analysis of the whole spectral dataset. They will be employed in subsequent papers describing the astrophysical results of the campaign.

astro-ph.HE↗

arXiv2025

Structured ionized winds shooting out from a quasar at relativistic speeds

Evidence indicates that supermassive black holes exist at the centers of most galaxies. Their mass correlates with the galactic bulge mass, suggesting a co-evolution with their host galaxies, most likely through powerful winds. X-ray observations have detected highly ionized winds outflowing at sub-relativistic speeds from the accretion disks around supermassive black holes. However, the limited spectral resolution of current X-ray instruments has left the physical structure and location of the winds poorly understood, hindering accurate estimates of their kinetic power. Here, the first XRISM observation of the luminous quasar, PDS 456, is reported. The high-resolution spectrometer Resolve onboard XRISM enabled the discovery of five discrete velocity components outflowing at 20-30% of the speed of light. This demonstrates that the wind structure is highly inhomogeneous, which likely consists of up to a million clumps. The mass outflow rate is estimated to be 60-300 solar masses per year, with the wind kinetic power exceeding the Eddington luminosity limit. Compared to the galaxy-scale outflows, the kinetic power is more than 3 orders of magnitude larger, while the momentum flux is 10 times larger. These estimates disfavor both energy- and momentum-driven outflow models. It suggests that such wind activity occurs in less than 10% of the quasar phase and/or that its energy/momentum is not efficiently transferred to the galaxy-scale outflows due to the clumpiness of the wind and the interstellar medium.

astro-ph.HE↗

arXiv2025

Thermal and Kinematic Properties of Ejecta in SN1987A revealed by XRISM

We present an analysis of high-resolution spectra from the shock-heated plasmas in SN~1987A, based on an observation using the Resolve instrument onboard the X-Ray Imaging and Spectroscopy Mission (XRISM).The 1.7--10 keV Resolve spectra are accurately represented by a single component, plane-parallel shock plasma model, with a temperature of $2.84_{-0.08}^{+0.09}$ keV and an ionization parameter of $2.64_{-0.45}^{+0.58} \times 10^{11}$ s cm$^{-3}$.The Resolve spectra are also well reproduced by the 3-D magneto-hydrodynamic simulation presented by Orlando et al. (2020) suggesting substantial contribution from the ejecta. The metal abundances obtained with Resolve align with the LMC value, indicating that the X-rays in 2024 originate from non-metal-rich shock-heated ejecta and the reverse shock has not reached the inner metal-rich region of ejecta. Doppler widths of the atomic lines from Si, S, and Fe correspond to velocities of 1,500--1,700 km s$^{-1}$, where the thermal broadening effects in this non-metal-rich plasma are negligible. Therefore, the line broadening seen in Resolve spectra is determined by the large bulk motion of ejecta. For reference, we determined a 90\% upper limit on non-thermal emission from a pulsar wind nebula at $4.3 \times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$ in the 2 -- 10 keV range, aligning with NuSTAR findings by Greco et al. (2022). Additionally, we searched for the $^{44}$Sc K line feature and found a $1\sigma$ upper limit of $1.0 \times 10^{-6}$ photons cm$^{-2}$ s$^{-1}$, which translates to an initial $^{44}$Ti mass of approximately $2 \times 10^{-4} M_{\odot}$, consistent with previous X-ray to soft gamma-ray observations (Boggs et al. 2015; Grebenev et al. 2012; Leising 2006).

astro-ph.HE↗

arXiv2025

The bulk motion of gas in the core of the Centaurus galaxy cluster

Galaxy clusters, the largest gravitationally bound structures in the Universe, contain vast amounts of dark matter, galaxies, and hot ionised gas known as the intracluster medium (ICM). In relaxed cluster cores, the ICM appears to cool radiatively faster than the age of the cluster, but the Galaxy clusters contain vast amounts of hot ionised gas known as the intracluster medium (ICM). In relaxed cluster cores, the radiative cooling time of the ICM is shorter than the age of the cluster, but the absence of line emission associated with cooling suggests heating mechanisms that offset the cooling, with feedback from active galactic nuclei (AGNs) being the most likely source. Turbulence and bulk motions, such as the oscillating ("sloshing") motion of the core gas in the cluster potential well, have also been proposed as mechanisms for heat distribution from the outside of the core. Here we present X-ray spectroscopic observations of the Centaurus galaxy cluster with the XRISM satellite. We find that the hot gas flows along the line of sight relative to the central galaxy, with velocities from 130 km/s to 310 km/s within ~30 kpc of the centre. This indicates bulk flow consistent with core gas sloshing. While the bulk flow may prevent excessive accumulation of cooled gas at the centre, it could distribute the heat injected by the AGN and bring in thermal energy from the surrounding ICM. The velocity dispersion of the gas is found to be only ~<120 km/s in the core, even within ~10 kpc of the AGN. This suggests that the AGN's influence on the surrounding ICM motion is limited in the cluster.

astro-ph.HE↗