arXiv subjects

Gerrit Schellenberger

Publications and source records attributed to Gerrit Schellenberger.

At least 37 records · Page 2Linked to original sources

arXiv2024

Mapping the imprints of stellar and AGN feedback in the circumgalactic medium with X-ray microcalorimeters

The Astro2020 Decadal Survey has identified the mapping of the circumgalactic medium (CGM, gaseous plasma around galaxies) as a key objective. We explore the prospects for characterizing the CGM in and around nearby galaxy halos with a future, large grasp X-ray microcalorimeter. We create realistic mock observations from hydrodynamical simulations (EAGLE, IllustrisTNG, and Simba) that demonstrate a wide range of potential measurements, which will address the open questions in galaxy formation and evolution. By including all background and foreground components in our mock observations, we show why it is impossible to perform these measurements with current instruments, such as X-ray CCDs, and only microcalorimeters will allow us to distinguish the faint CGM emission from the bright Milky Way (MW) foreground emission lines. We find that individual halos of MW mass can, on average and depending on star formation rate, be traced out to large radii, around R500, and for larger galaxies even out to R200, using prominent emission lines, such as OVII, or OVIII. Furthermore, we show that emission line ratios for individual halos can reveal the radial temperature structure. Substructure measurements show that it will be possible to relate azimuthal variations to the feedback mode of the galaxy. We demonstrate the ability to construct temperature, velocity, and abundance ratio maps from spectral fitting for individual galaxy halos, which reveal rotation features, AGN outbursts, and enrichment.

astro-ph.GA↗

arXiv2024

Surface Brightness Fluctuations in Two SPT clusters: a Pilot Study

Studies of surface brightness fluctuations in the intracluster medium (ICM) present an indirect probe of turbulent properties such as the turbulent velocities, injection scales, and the slope of the power spectrum of fluctuations towards smaller scales. With the advancement of Sunyaev-Zel'dovich (SZ) studies and surveys relative to X-ray observations, we seek to investigate surface brightness fluctuations in a sample of SPT-SZ clusters which also have archival \textit{XMM-Newton} data. Here we present a pilot study of two typical clusters in that sample: SPT-CLJ0232-4421 and SPT-CLJ0638-5358. We infer injection scales larger than 500 kpc in both clusters and Mach numbers $\approx 0.5$ in SPT-CLJ0232-4421 and Mach numbers $\approx 0.6 - 1.6$ in SPT-CLJ0638-5358, which has a known shock. We find hydrostatic bias values for $M_{500}$ less than 0.2 for SPT-CLJ0232-4421 and less than 0.1 for SPT-CLJ0638-5358. These results show the importance to assess its quantitative values via a detailed multiwavelength approach and suggest that the drivers of turbulence may occur at quite larger scales.

astro-ph.CO↗

arXiv2023

ZWCL 1856.8 : A rare double radio relic system captured within NuSTAR and Chandra field of view

Observations of galaxy cluster mergers provide insights on the particle acceleration and heating mechanisms taking place within the intracluster medium. Mergers form shocks that propagate through the plasma, which result in shock/cold fronts in the X-ray, and radio halos and/or relics in the radio regime. The connection between these tracers and the mechanisms driving non-thermal processes, such as inverse Compton, are not well understood. ZWCL 1856.8 is one of the few known double radio relic systems that originate from nearly head-on collisions observed close to the plane of the sky. For the first time, we study NuSTAR and Chandra observations of such a system that contains both relics within their field of view. The spectro-imaging analyses results of the system suggest weak shock fronts with $\mathcal{M}$ numbers within 2$σ$ of the radio derived values, and provide evidence of inverse Compton emission at both relic sites. Our findings have great uncertainties due to the shallow exposure times available. Deeper NuSTAR and Chandra data are crucial for studying the connection of the radio and X-ray emission features and for constraining the thermal vs. non-thermal emission contributions in this system. We also present methods and approaches on how to investigate X-ray properties of double relic systems by taking full advantage of the complementary properties of NuSTAR and Chandra missions.

astro-ph.HE↗

arXiv2023

Jet reorientation in central galaxies of clusters and groups: insights from VLBA and Chandra data

Recent observations of galaxy clusters and groups with misalignments between their central AGN jets and X-ray cavities, or with multiple misaligned cavities, have raised concerns about the jet - bubble connection in cooling cores, and the processes responsible for jet realignment. To investigate the frequency and causes of such misalignments, we construct a sample of 16 cool core galaxy clusters and groups. Using VLBA radio data we measure the parsec-scale position angle of the jets, and compare it with the position angle of the X-ray cavities detected in Chandra data. Using the overall sample and selected subsets, we consistently find that there is a 30% - 38% chance to find a misalignment larger than $ΔΨ= 45^{\circ}$ when observing a cluster/group with a detected jet and at least one cavity. We determine that projection may account for an apparently large $ΔΨ$ only in a fraction of objects ($\sim$35%), and given that gas dynamical disturbances (as sloshing) are found in both aligned and misaligned systems, we exclude environmental perturbation as the main driver of cavity - jet misalignment. Moreover, we find that large misalignments (up to $\sim90^{\circ}$) are favored over smaller ones ($45^{\circ}\leqΔΨ\leq70^{\circ}$), and that the change in jet direction can occur on timescales between one and a few tens of Myr. We conclude that misalignments are more likely related to actual reorientation of the jet axis, and we discuss several engine-based mechanisms that may cause these dramatic changes.

astro-ph.GA↗

arXiv2023

LEM All-Sky Survey: Soft X-ray Sky at Microcalorimeter Resolution

The Line Emission Mapper (LEM) is an X-ray Probe with with spectral resolution ~2 eV FWHM from 0.2 to 2.5 keV and effective area >2,500 cm$^2$ at 1 keV, covering a 33 arcmin diameter Field of View with 15 arcsec angular resolution, capable of performing efficient scanning observations of very large sky areas and enabling the first high spectral resolution survey of the full sky. The LEM-All-Sky Survey (LASS) is expected to follow the success of previous all sky surveys such as ROSAT and eROSITA, adding a third dimension provided by the high resolution microcalorimeter spectrometer, with each 15 arcsec pixel of the survey including a full 1-2 eV resolution energy spectrum that can be integrated over any area of the sky to provide statistical accuracy. Like its predecessors, LASS will provide both a long-lasting legacy and open the door to the unknown, enabling new discoveries and delivering the baseline for unique GO studies. No other current or planned mission has the combination of microcalorimeter energy resolution and large grasp to cover the whole sky while maintaining good angular resolution and imaging capabilities. LASS will be able to probe the physical conditions of the hot phases of the Milky Way at multiple scales, from emission in the Solar system due to Solar Wind Charge eXchange, to the interstellar and circumgalactic media, including the North Polar Spur and the Fermi/eROSITA bubbles. It will measure velocities of gas in the inner part of the Galaxy and extract the emissivity of the Local Hot Bubble. By maintaining the original angular resolution, LASS will also be able to study classes of point sources through stacking. For classes with ~$10^4$ objects, it will provide the equivalent of 1 Ms of high spectral resolution data. We describe the technical specifications of LASS and highlight the main scientific objectives that will be addressed. (Abridged)

astro-ph.IM↗

arXiv2023

The Hydrostatic Mass of A478: Discrepant Results From Chandra, NuSTAR, and XMM-Newton

Galaxy clusters are the most recently formed and most massive, gravitationally bound structures in the universe. The number of galaxy clusters formed is highly dependent on cosmological parameters, such as the dark matter density, $σ_8$, and $Ω_m$. The number density is a function of the cluster mass, which can be estimated from the density and temperature profiles of the intracluster medium (ICM) under the assumption of hydrostatic equilibrium. The temperature of the plasma, hence its mass, is calculated from the X-ray spectra. However, effective area calibration uncertainties in the soft band result in significantly different temperature measurements from various space-based X-ray telescopes. NuSTAR is potentially less susceptible to these issues than Chandra and XMM-Newton, having larger effective area, particularly at higher energies, enabling high precision temperature measurements. In this work, we present analyses of Chandra, NuSTAR, and XMM-Newton data of Abell 478 to investigate the nature of this calibration discrepancy. We find that NuSTAR temperatures are on average $\sim$11% lower than that of Chandra, and XMM-Newton temperatures are on average $\sim$5% lower than that of NuSTAR. This results in a NuSTAR mass at $r_{2500,Chandra}$ of $M_{2500,NuSTAR}=3.39^{+0.07}_{-0.07}\times10^{14}$ $M_{\odot}$, which is $\sim$10% lower than that of $M_{2500,Chandra}$ and $\sim$4% higher than $M_{2500,XMM-Newton}$.

astro-ph.CO↗

arXiv2023

X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback

We derive predictions from state-of-the-art cosmological galaxy simulations for the spatial distribution of the hot circumgalactic medium (CGM, ${\rm [0.1-1]R_{200c}}$) through its emission lines in the X-ray soft band ($[0.3-1.3]$ keV). In particular, we compare IllustrisTNG, EAGLE, and SIMBA and focus on galaxies with stellar mass $10^{10-11.6}\, \MSUN$ at $z=0$. The three simulation models return significantly different surface brightness radial profiles of prominent emission lines from ionized metals such as OVII(f), OVIII, and FeXVII as a function of galaxy mass. Likewise, the three simulations predict varying azimuthal distributions of line emission with respect to the galactic stellar planes, with IllustrisTNG predicting the strongest angular modulation of CGM physical properties at radial range ${\gtrsim0.3-0.5\,R_{200c}}$. This anisotropic signal is more prominent for higher-energy lines, where it can manifest as X-ray eROSITA-like bubbles. Despite different models of stellar and supermassive black hole (SMBH) feedback, the three simulations consistently predict a dichotomy between star-forming and quiescent galaxies at the Milky-Way and Andromeda mass range, where the former are X-ray brighter than the latter. This is a signature of SMBH-driven outflows, which are responsible for quenching star formation. Finally, we explore the prospect of testing these predictions with a microcalorimeter-based X-ray mission concept with a large field-of-view. Such a mission would probe the extended hot CGM via soft X-ray line emission, determine the physical properties of the CGM, including temperature, from the measurement of line ratios, and provide critical constraints on the efficiency and impact of SMBH feedback on the CGM.

astro-ph.GA↗

arXiv2023

A detached double X-ray tail in the merging galaxy cluster Z8338 with a large double tail

When subhalos infall into galaxy clusters, their gas content is ram pressure stripped by the intracluster medium (ICM) and may turn into cometary tails. We report the discovery of two spectacular X-ray double tails in a single galaxy cluster, Z8338, revealed by 70 ks Chandra observations. The brighter one, with an X-ray bolometric luminosity of $3.9 \times 10^{42}{\rm\ erg\ s}^{-1}$, is a detached tail stripped from the host halo and extended at least 250 kpc in projection. The head of the detached tail is a cool core with the front tip of the cold front $\sim$ 30 kpc away from the nucleus of its former host galaxy. The cooling time of the detached cool core is $\sim 0.3$ Gyr. For the detached gas, the gravity of the once-associated dark matter halo further enhances the Rayleigh-Taylor (RT) instability. From its survival, we find that a magnetic field of a few $μ$G is required to suppress the hydrodynamic instability. The X-ray temperature in the tail increases from 0.9 keV at the front tip to 1.6 keV in the wake region, which suggests the turbulent mixing with the hotter ICM. The fainter double X-ray tail, with a total X-ray luminosity of $2.7 \times 10^{42}{\rm\ erg\ s}^{-1}$, appears to stem from the cool core of a subcluster in Z8338, and likely was formed during the ongoing merger. This example suggests that X-ray cool cores can be displaced and eventually destroyed by mergers, while the displaced cool cores can survive for some extended period of time.

astro-ph.GA↗

arXiv2023

Resonant scattering of the OVII X-ray emission line in the circumgalactic medium of TNG50 galaxies

We study the impact of resonantly scattered X-ray line emission on the observability of the hot circumgalactic medium (CGM) of galaxies. We apply a Monte Carlo radiative transfer post-processing analysis to the high-resolution TNG50 cosmological magnetohydrodynamical galaxy formation simulation. This allows us to model the resonant scattering of OVII(r) X-ray photons within the complex, multi-phase, multi-scale CGM. The resonant transition of the OVII He-like triplet is one of the brightest, and most promising, X-ray emission lines for detecting the hot CGM and measuring its physical properties. We focus on galaxies with stellar masses 10 < log(M*/Msun) < 11 at z ~ 0. After constructing a model for OVII(r) emission from the central galaxy as well as from CGM gas, we forward model these intrinsic photons to derive observable surface brightness maps. We find that scattering significantly boosts the observable OVII(r) surface brightness of the extended and diffuse CGM. This enhancement can be large -- an order of magnitude on average at a distance of 200 projected kpc for high-mass M* = 10^10.7 Msun galaxies. The enhancement is larger for lower mass galaxies, and can even reach a factor of 100, across the extended CGM. Galaxies with higher star formation rates, AGN luminosities, and central OVII(r) luminosities all have larger scattering enhancements, at fixed stellar mass. Our results suggest that next-generation X-ray spectroscopic missions including XRISM, LEM, ATHENA, and HUBS -- which aim to detect the hot CGM in emission -- could specifically target halos with significant enhancements due to resonant scattering.

astro-ph.GA↗

arXiv2023

Circumgalactic Medium on the Largest Scales: Detecting X-ray Absorption Lines with Large-Area Microcalorimeters

The circumgalactic medium (CGM) plays a crucial role in galaxy evolution as it fuels star formation, retains metals ejected from the galaxies, and hosts gas flows in and out of galaxies. For Milky Way-type and more massive galaxies, the bulk of the CGM is in hot phases best accessible at X-ray wavelengths. However, our understanding of the CGM remains largely unconstrained due to its tenuous nature. A promising way to probe the CGM is via X-ray absorption studies. Traditional absorption studies utilize bright background quasars, but this method probes the CGM in a pencil beam, and, due to the rarity of bright quasars, the galaxy population available for study is limited. Large-area, high spectral resolution X-ray microcalorimeters offer a new approach to exploring the CGM in emission and absorption. Here, we demonstrate that the cumulative X-ray emission from cosmic X-ray background sources can probe the CGM in absorption. We construct column density maps of major X-ray ions from the Magneticum simulation and build realistic mock images of nine galaxies to explore the detectability of X-ray absorption lines arising from the large-scale CGM. We conclude that the OVII absorption line is detectable around individual massive galaxies at the $3σ-6σ$ confidence level. For Milky Way-type galaxies, the OVII and OVIII absorption lines are detectable at the $\sim\,6σ$ and $\sim\,3σ$ levels even beyond the virial radius when co-adding data from multiple galaxies. This approach complements emission studies, does not require additional exposures, and will allow probing of the baryon budget and the CGM at the largest scales.

astro-ph.GA↗

arXiv2023

Inferences from surface brightness fluctuations of Zwicky 3146 via the Sunyaev-Zeldovich effect and X-ray observations

The galaxy cluster Zwicky 3146 is a sloshing cool core cluster at $z{=}0.291$ that in SZ imaging does not appear to exhibit significant pressure substructure in the intracluster medium (ICM). We perform a surface brightness fluctuation analysis via Fourier amplitude spectra on SZ (MUSTANG-2) and X-ray (XMM-Newton) images of this cluster. These surface brightness fluctuations can be deprojected to infer pressure and density fluctuations from the SZ and X-ray data, respectively. In the central region (Ring 1, $r < 100^{\prime\prime} = 440$ kpc, in our analysis) we find fluctuation spectra that suggest injection scales around 200 kpc ($\sim 140$ kpc from pressure fluctuations and $\sim 250$ kpc from density fluctuations). When comparing the pressure and density fluctuations in the central region, we observe a change in the effective thermodynamic state from large to small scales, from isobaric (likely due to the slow sloshing) to adiabatic (due to more vigorous motions). By leveraging scalings from hydrodynamical simulations, we find an average 3D Mach number $\approx0.5$. We further compare our results to other studies of Zwicky 3146 and, more broadly, to other studies of fluctuations in other clusters.

astro-ph.CO↗

arXiv2023

Waking the monster: the onset of AGN feedback in galaxy clusters hosting young central radio galaxies

The investigation of the feedback cycle in galaxy clusters has historically been performed for systems where feedback is ongoing ("mature-feedback" clusters), that is where the central radio galaxy has inflated radio lobes, pushing aside the intracluster medium (ICM). In this pilot study we present results from "pre-feedback" clusters, where the central newly active radio galaxies (age $<10^{3}$ yr) may not yet have had time to alter the thermodynamic state of the ICM. We analyze $Chandra$ and MUSE observations of two such systems, evaluating the hot gas entropy and cooling time profiles, and characterizing the morphology and kinematics of the warm gas. Based on our exploratory study of these two sources, we find that the hot gas meets the expectations for an as-yet unheated ICM. Specifically, the entropy and cooling time of pre-feedback clusters within 20 kpc from the center fall below those of mature-feedback clusters by a factor $\sim$2. We speculate that with an estimated mechanical power of $\sim10^{44} - 10^{45}$ erg s$^{-1}$, the two young radio galaxies may restore the entropy levels in a few tens of Myr, which are typical values of power outbursts and lifetimes for radio galaxies in clusters. Conversely, the properties of the gas at $\sim10^{4}$ K seem to remain invariant between the two feedback stages, possibly suggesting that the warm gas reservoir accumulates over long periods ($10^{7}$ - $10^{8}$ yr) during the growth of the radio galaxy. We conclude that the exploratory results obtained from our analysis of two cluster-central young radio galaxies are crucial in the context of understanding the onset of active galactic nuclei feedback, and they provide enough motivation for further investigation of similar cases.

astro-ph.GA↗

arXiv2023

Line Emission Mapper (LEM): Probing the physics of cosmic ecosystems

The Line Emission Mapper (LEM) is an X-ray Probe for the 2030s that will answer the outstanding questions of the Universe's structure formation. It will also provide transformative new observing capabilities for every area of astrophysics, and to heliophysics and planetary physics as well. LEM's main goal is a comprehensive look at the physics of galaxy formation, including stellar and black-hole feedback and flows of baryonic matter into and out of galaxies. These processes are best studied in X-rays, and emission-line mapping is the pressing need in this area. LEM will use a large microcalorimeter array/IFU, covering a 30x30' field with 10" angular resolution, to map the soft X-ray line emission from objects that constitute galactic ecosystems. These include supernova remnants, star-forming regions, superbubbles, galactic outflows (such as the Fermi/eROSITA bubbles in the Milky Way and their analogs in other galaxies), the Circumgalactic Medium in the Milky Way and other galaxies, and the Intergalactic Medium at the outskirts and beyond the confines of galaxies and clusters. LEM's 1-2 eV spectral resolution in the 0.2-2 keV band will make it possible to disentangle the faintest emission lines in those objects from the bright Milky Way foreground, providing groundbreaking measurements of the physics of these plasmas, from temperatures, densities, chemical composition to gas dynamics. While LEM's main focus is on galaxy formation, it will provide transformative capability for all classes of astrophysical objects, from the Earth's magnetosphere, planets and comets to the interstellar medium and X-ray binaries in nearby galaxies, AGN, and cooling gas in galaxy clusters. In addition to pointed observations, LEM will perform a shallow all-sky survey that will dramatically expand the discovery space.

astro-ph.IM↗

arXiv2023

Feedback in the merging galaxy group NGC6338

The galaxy group NGC6338 is one of the most violent group-group mergers known to date. While the central dominant galaxies rush at each other at 1400km/s along the line of sight, with dramatic gas heating and shock fronts detected, the central gas in the BCGs remains cool. There are also indications of feedback from active galactic nuclei (AGNs), and neither subcluster core has been disrupted. With our deep radio uGMRT data at 383MHz and 650MHz we clearly detect a set of large, old lobes in the southern BCG coinciding with the X-ray cavities, while the northern, and smaller BCG appears slightly extended in the radio. The southern BCG also hosts a smaller younger set of lobes, perpendicular to the larger lobes, but also coinciding with the inner X-ray cavities, and matching the jet direction in the parsec-resolution VLBA image. Our spectral analysis confirms the history of two feedback cycles. The high radio frequency analysis classifies the compact source in the southern BCG with a powerlaw, while ruling out a significant contribution from accretion. The radio lightcurve over 3 decades shows a change about 10 years ago, which might be related to ongoing feedback in the core. The southern BCG in the NGC6338 merger remains another prominent case where the direction of jet-mode feedback between two cycles changed dramatically.

astro-ph.GA↗

arXiv2022

Intracluster magnetic filaments and an encounter with a radio jet

Thin synchrotron-emitting filaments are increasingly seen in the intracluster medium (ICM). We present the first example of a direct interaction between a magnetic filament, a radio jet, and a dense ICM clump in the poor cluster Abell 194. This enables the first exploration of the dynamics and possible histories of magnetic fields and cosmic rays in such filaments. Our observations are from the MeerKAT Galaxy Cluster Legacy Survey and the LOFAR Two Metre Sky Survey. Prominent 220 kpc long filaments extend east of radio galaxy 3C40B, with very faint extensions to 300 kpc, and show signs of interaction with its northern jet. They curve around a bend in the jet and intersect the jet in Faraday depth space. The X-ray surface brightness drops across the filaments; this suggests that the relativistic particles and fields contribute significantly to the pressure balance and evacuate the thermal plasma in a $\sim$35 kpc cylinder. We explore whether the relativistic electrons could have streamed along the filaments from 3C40B, and present a plausible alternative whereby magnetized filaments are a) generated by shear motions in the large-scale, post-merger ICM flow, b) stretched by interactions with the jet and flows in the ICM, amplifying the embedded magnetic fields, and c) perfused by re-energized relativistic electrons through betatron-type acceleration or diffusion of turbulently accelerated ICM cosmic ray electrons. We use the Faraday depth measurements to reconstruct some of the 3D structures of the filaments and of 3C40A and B.

astro-ph.HE↗

arXiv2022

The contribution of non-central radio galaxies to AGN feedback in rich galaxy clusters

We present a combined radio/X-ray study of six massive galaxy clusters, aimed at determining the potential for heating of the intra-cluster medium (ICM) by non-central radio galaxies. Since X-ray cavities associated with the radio lobes of non-central galaxies are generally not detectable, we use Giant Metrewave Radio Telescope 610~MHz observations to identify jet sources and estimate their size, and Chandra data to estimate the pressure of the surrounding ICM. In the radio, we detect 4.5% of galaxies above the spectroscopic survey limit (M*K+2.0) of the Arizona cluster redshift survey (ACReS) which covers five of our six clusters. Approximately one tenth of these are extended radio sources. Using star formation (SF) rates determined from mid-infrared data, we estimate the expected contribution to radio luminosity from the stellar population of each galaxy, and find that most of the unresolved or poorly-resolved radio sources are likely star formation dominated. The relatively low frequency and good spatial resolution of our radio data allows us to trace star formation emission down to galaxies of stellar mass ~10^9.5 Msol. We estimate the enthalpy of the (AGN dominated) jet/lobe and tailed sources, and place limits on the energy available from unresolved radio jets. We find jet powers in the range ~10^43-10^46 erg/s, comparable to those of brightest cluster galaxies. Our results suggest that while cluster-central sources are the dominant factor balancing ICM cooling over the long term, non-central sources may have a significant impact, and that further investigation is possible and warranted.

astro-ph.CO↗

arXiv2021

The unusually weak and exceptionally steep radio relic in Abell 2108

Mergers between galaxy clusters often drive shocks into the intra cluster medium (ICM), the effects of which are sometimes visible via temperature and density jumps in the X-ray, and via radio emission from relativistic particles energized by the shock's passage. Abell2108 was selected as a likely merger system through comparing the X-ray luminosity to the Planck Sunyaev-Zeldovich signal, where this cluster appeared highly X-ray underluminous. Follow up observations confirmed it to be a merging low mass cluster featuring two distinct subclusters, both with a highly disturbed X-ray morphology. Giant Metrewave Radio Telescope (GMRT) data covering 120-750MHz show an extended radio feature resembling a radio relic, near the location of a temperature discontinuity in the X-rays. We measure a Mach number from the X-ray temperature jump. Several characteristics of radio relics are found in Abell2108, making this cluster one of the few low mass mergers likely hosting a radio relic. The radio spectrum is exceptionally steep, and the radio power is very weak (P1.4GHz=1E22W/Hz). To account for the shock/relic offset, we propose a scenario in which the shock created the relic by re-accelerating a cloud of pre-existing relativistic electrons and then moved away, leaving behind a fading relic. The electron aging timescale derived from the high-frequency steepening in the relic spectrum is consistent with the shock travel time to the observed X-ray discontinuity. However, the lower flux in GMRT band 4 data causing the steepening could be due to instrumental limitations, and deeper radio data are needed to constrain the spectral slope of the relic at high frequencies.

astro-ph.GA↗

arXiv2021

Molecular gas along the old radio jets of the cluster-central type 2 quasar IRAS 09104+4109

We present Northern Extended Millimeter Array (NOEMA) CO(2-1) maps of the z=0.4418 cluster-central QSO IRAS 09104+4109, which trace ~4.5x10^10 Msol of molecular gas in and around the galaxy. As in many low redshift cool core clusters, the molecular gas is located in a series of clumps extending along the old radio jets and lobes. It has a relatively low velocity dispersion (336 [+39,-35] km/s FWHM) and shows no velocity gradients indicative of outflow or infall. Roughly half the gas is located in a central clump on the northeast side of the galaxy, overlapping a bright ionized gas filament and a spur of excess X-ray emission, suggesting that this is a location of rapid cooling. The molecular gas is unusually extended, out to ~55 kpc radius, comparable to the scale of the filamentary nebula in the Perseus cluster, despite the much higher redshift of this system. The extent falls within the thermal instability radius of the intracluster medium (ICM), with t_cool/t_ff<25 and t_cool}/t_eddy~1 within ~70 kpc. Continuum measurements at 159.9 GHz from NOEMA and 850 micron from the JCMT SCUBA-2 show excess far infrared emission, which we interpret as free-free emission arising from the ongoing starburst. These observations suggest that ICM cooling is not strongly affected by the buried QSO, and that cooling from the ICM can build gas reservoirs sufficient to fuel quasar-mode activity and drive the reorientation of the central AGN.

astro-ph.GA↗