We simulate stacked observations of nearby hot X-ray coronae associated with galaxies in the EAGLE and Illustris-TNG hydrodynamic simulations. A forward modeling pipeline is developed to predict 4 yr ...eROSITA observations and stacked image analysis, including the effects of instrumental and astrophysical backgrounds. We propose an experiment to stack z 0.01 galaxies separated by specific star formation rate (sSFR) to examine how the hot (T ≥ 106 K) circumgalactic medium (CGM) differs for high- and low-sSFR galaxies. The simulations indicate that the hot CGM of low-mass ( ), high-sSFR (defined as the top one-third ranked by sSFR) central galaxies will be detectable to a galactocentric radius r 30-50 kpc. Both simulations predict lower luminosities at fixed stellar mass for the low-sSFR galaxies (the lower third of sSFR) with Illustris-TNG predicting 3× brighter coronae around high-sSFR galaxies than EAGLE. Both simulations predict detectable emission out to r 150-200 kpc for stacks centered on high-mass ( ) galaxies, with EAGLE predicting brighter X-ray halos. The extended soft X-ray luminosity correlates strongly and positively with the mass of circumgalactic gas within the virial radius (fCGM). Prior analyses of both simulations have established that fCGM is reduced by expulsive feedback driven mainly by black hole growth, which quenches galaxy growth by inhibiting replenishment of the interstellar medium. Both simulations predict that eROSITA stacks should not only conclusively detect and resolve the hot CGM around L* galaxies for the first time, but provide a powerful probe of how the baryon cycle operates, for which there remains an absence of consensus between state-of-the-art simulations.
ABSTRACT
We present a detailed analysis of the elemental abundances distribution of the Virgo cluster using XMM–Newton observations. We included in the analysis a new EPIC-pn energy scale calibration ...which allow us to measure velocities with uncertainties down to Δv ∼150 km s−1. We investigate the radial distribution of O, Ne, Mg, Si, Ar, S, Ca, Ni, and Fe. We found that the best-fitting model is close to a single-temperature component for distances >80 kpc and the cooler gas is more metal rich. Discontinuities in temperature are found around ∼30 and ∼90 kpc, which correspond to the radius of the cold fronts. We modelled elemental X/Fe ratio profiles with a linear combination of SNIa and SNcc models. We found a flat radial distribution of SNIa ratio over the total cluster enrichment, which supports an early ICM enrichment scenario, with most of the metals present being produced prior to clustering.
ABSTRACT
We have found evidence of bulk velocities following active galactic nucleus (AGN) bubbles in the Virgo cluster and galaxy motions in the Centaurus cluster. In order to increase the sample ...and improve our understanding of the intracluster medium (ICM), we present the results of a detailed mapping of the Ophiuchus cluster with XMM–Newton to measure bulk flows through very accurate Fe-K measurements. To measure the gas velocities, we use a novel EPIC-pn energy-scale calibration, which uses the Cu Kα instrumental line as reference for the line emission. We created 2D spectral maps for the velocity, metallicity, temperature, density, entropy, and pressure with a spatial resolution of 0.25 arcmin (∼26 kpc). The ICM velocities in the central regions where AGN feedback is most important are similar to the velocity of the brightest cluster galaxy. We have found a large interface region where the velocity changes abruptly from blueshifted to redshifted gas that follows a sharp surface brightness discontinuity. We also found that the metallicities and temperatures do not change as we move outwards from the giant radio fossil previously identified in radio observations of the cluster. Finally, we have found a contribution from the kinetic component of $\lt 25{{\ \rm per\ cent}}$ to the total energy budget for large distances.
ABSTRACT
There are few direct measurements of the intracluster medium (ICM) velocity structure, despite its importance for understanding clusters. We present a detailed analysis of the velocity ...structure of the Centaurus cluster using XMM–Newton observations. Using a new European Photon Imaging Camera-pn energy scale calibration, which uses the Cu Kα instrumental line as reference, we are able to obtain velocity measurements with uncertainties down to Δ$\mathit{ v}$ ∼ 79 km s−1. We create 2D spectral maps for the velocity, metallicity, temperature, density, entropy, and pressure with a spatial resolution of 0.25 arcmin. We have found that the velocity structure of the ICM is similar to the velocity structure of the main galaxies, while the cold fronts are likely moving in a plane perpendicular to our line of sight with low velocity. Finally, we have found a contribution from the kinetic component of $\lt 25{{\ \rm per\ cent}}$ to the total energetic budget for a radius >30 kpc.
ABSTRACT
We investigate how the X-ray circumgalactic medium (CGM) of present-day galaxies depends on galaxy morphology and azimuthal angle using mock observations generated from the EAGLE ...cosmological hydrodynamic simulation. By creating mock stacks of eROSITA-observed galaxies oriented to be edge-on, we make several observationally testable predictions for galaxies in the stellar mass range M⋆ = 1010.7–11.2 M⊙. The soft X-ray CGM of disc galaxies is between 60 and 100 per cent brighter along the semimajor axis compared to the semiminor axis, between 10 and 30 kpc. This azimuthal dependence is a consequence of the hot (T > 106 K) CGM being non-spherical: specifically, it is flattened along the minor axis such that denser and more luminous gas resides in the disc plane and corotates with the galaxy. Outflows enrich and heat the CGM preferentially perpendicular to the disc, but we do not find an observationally detectable signature along the semiminor axis. Spheroidal galaxies have hotter CGMs than disc galaxies related to spheroids residing at higher halo masses, which may be measurable through hardness ratios spanning the 0.2–1.5 keV band. While spheroids appear to have brighter CGMs than discs for the selected fixed M⋆ bin, this owes to spheroids having higher stellar and halo masses within that M⋆ bin, and obscures the fact that both simulated populations have similar total CGM luminosities at the exact same M⋆. Discs have brighter emission inside 20 kpc and more steeply declining profiles with radius than spheroids. We predict that the eROSITA 4-yr all-sky survey should detect many of the signatures we predict here, although targeted follow-up observations of highly inclined nearby discs after the survey may be necessary to observe some of our azimuthally dependant predictions.
Context.
Galaxy clusters are the most massive bound objects in the recent history of the universe; the number density of galaxy clusters as a function of mass and redshift is a sensitive function of ...the cosmological parameters. To use clusters for cosmological parameter studies, it is necessary to determine their masses as accurately as possible, which is typically done via scaling relations between mass and observables.
Aims.
X-ray observables can be biased by a number of effects, including multiphase gas and projection effects, especially in the case where cluster temperatures and luminosities are estimated from single-model fits to all of the emission with an overdensity radius such as
r
500c
. Using simulated galaxy clusters from a realistic cosmological simulation, our aim is to determine the importance of these biases in the context of Spectrum-Roentgen-Gamma/eROSITA observations of clusters.
Methods.
We extracted clusters from the
Box2_hr
simulation from the Magneticum suite, and simulated synthetic eROSITA observations of these clusters using
PHOX
to generate the photons and the end-to-end simulator
SIXTE
to trace them through the optics and simulate the detection process. We fitted the spectra from these observations and compared the fitted temperatures and luminosities to the quantities derived from the simulations. We fitted an intrinsically scattered
L
X
−
T
scaling relation to these measurements following a Bayesian approach with which we fully took into account the selection effects and the mass function.
Results.
The largest biases on the estimated temperature and luminosities of the clusters come from the inadequacy of single-temperature model fits to represent emission from multiphase gas, and from a bias arising from cluster emission within the projected
r
500c
along the line of sight but outside of the spherical
r
500c
. We find that the biases on temperature and luminosity due to the projection of emission from other clusters within
r
500c
is comparatively small. We find eROSITA-like measurements of Magneticum clusters following a
L
X
−
T
scaling relation that has a broadly consistent but slightly shallower slope compared to the literature values. We also find that the intrinsic scatter of
L
X
at given
T
is lower compared to the recent observational results where the selection effects are fully considered.
The Fanaroff–Riley Class II radio galaxy Cygnus A hosts jets that produce radio emission, X-ray cavities, cocoon shocks, and X-ray hotspots, where the jet interacts with the ICM. Surrounding one ...hotspot is a peculiar “hole” feature, which appears as a deficit in X-ray emission. We used relativistic hydrodynamic simulations of a collimated jet interacting with an inclined interface between lobe and cluster plasma to model the basic processes that may lead to such a feature. We found that the jet reflects off of the interface into a broad, turbulent flow back out into the lobe, which is dominated by gas stripped from the interface at first and from the intracluster medium itself at later times. We produced simple models of X-ray emission from the ICM, the hotspot, and the reflected jet to show that a hole of emission surrounding the hotspot as seen in Cygnus A may be produced by Doppler de-boosting of the emission from the reflected jet, as seen by an observer with a sight line nearly along the axis of the outgoing material.
ABSTRACT We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously undetected filaments of star formation, ...extending to radii of ∼50-100 kpc in multiple directions. Combined UV-optical spectroscopy of the central galaxy reveals a massive (2 × 109 M ), young (∼4.5 Myr) population of stars, consistent with a time-averaged star formation rate of 610 50 M yr−1. We report a strong detection of O vi λλ1032,1038, which appears to originate primarily in shock-heated gas, but may contain a substantial contribution (>1000 M yr−1) from the cooling intracluster medium (ICM). We confirm the presence of deep X-ray cavities in the inner ∼10 kpc, which are among the most extreme examples of radio-mode feedback detected to date, implying jet powers of 2-7 × 1045 erg s−1. We provide evidence that the active galactic nucleus inflating these cavities may have only recently transitioned from "quasar-mode" to "radio-mode," and may currently be insufficient to completely offset cooling. A model-subtracted residual X-ray image reveals evidence for prior episodes of strong radio-mode feedback at radii of ∼100 kpc, with extended "ghost" cavities indicating a prior epoch of feedback roughly 100 Myr ago. This residual image also exhibits significant asymmetry in the inner ∼200 kpc (0.15R500), reminiscent of infalling cool clouds, either due to minor mergers or fragmentation of the cooling ICM. Taken together, these data reveal a rapidly evolving cool core which is rich with structure (both spatially and in temperature), is subject to a variety of highly energetic processes, and yet is cooling rapidly and forming stars along thin, narrow filaments.
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