Strong Evidence for Cosmic Ray-Supported $\sim$L${}^{\ast }$ Galaxy Halos via X-ray \& tSZ Constraints

Abstract

Many state-of-the-art galaxy simulations featuring traditional feedback modes have significant challenges producing enough extended soft X-ray ($\sim 0.5-2$ keV) emission at R $\sim 0.5-1$ R${}_{\mathrm{vir}}$ observed around galaxies with stellar masses M${}_{\ast }\lesssim 10^{11}{\mathrm{M}}_{\odot }$, without violating galaxy mass function constraints. Moreover, thermal Sunyaev-Zel'dovich (tSZ) measurements probing the thermal pressure of similar galaxies indicate it is orders-of-magnitude lower than predictions from simple halo hydrodynamics and many hydrodynamical simulations. We demonstrate that these constraints can be met congruously with a large non-thermal pressure contribution in the form of cosmic rays (CRs) from SNe and/or AGN, which lowers the tSZ signal while CR leptons produce plentiful soft X-rays via inverse Compton scattering of the CMB. The combination of these two observations is far more constraining on the pressure budget of galactic halos than either alone -- if these novel tSZ and X-ray observations are borne out by future studies, then taken together they reveal \textit{the strongest evidence for CR support in halos to date}. Conversely, it is very difficult to produce the extended X-rays via traditional thermal emission without increasing the overall thermal pressure and thus tSZ signal in tandem, making these tensions even worse. Finally, tSZ \& X-rays together unlock a novel observational method to constrain halo CR pressure relative to thermal pressure, with implications for CR transport parameters and AGN feedback energetics across various galaxy mass scales. Taking the currently observed constraints at M${}_{\mathrm{halo}}\sim 10^{12}{\mathrm{M}}_{\odot }$ imply the halo CR pressure must at least be equal to the gas thermal pressure.

14 pages (10.5 pages main text, 3.5 pages references), 4 figures. Updating with version accepted in The Astrophysical Journal Letters. Comments and questions most welcome!

References in corpus (34)

• The EAGLE project: Simulating the evolution and assembly of galaxies and their environments
• Heating Hot Atmospheres with Active Galactic Nuclei
• Simba: Cosmological Simulations with Black Hole Growth and Feedback
• The COS-Halos Survey: Physical Conditions and Baryonic Mass in the Low-Redshift Circumgalactic Medium
• Dark Energy Survey Year 3 Results: Cosmology from Cosmic Shear and Robustness to Data Calibration
• The CAMELS project: Cosmology and Astrophysics with MachinE Learning Simulations
• Global cosmic-ray related luminosity and energy budget of the Milky Way
• The stellar-to-halo mass relation over the past 12 Gyr
• FIRE-3: Updated Stellar Evolution Models, Yields, & Microphysics and Fitting Functions for Applications in Galaxy Simulations
• Testing Physical Models for Cosmic Ray Transport Coefficients on Galactic Scales: Self-Confinement and Extrinsic Turbulence at GeV Energies
• Simulating Groups and the IntraGroup Medium: The Surprisingly Complex and Rich Middle Ground Between Clusters and Galaxies
• New very local interstellar spectra for electrons, positrons, protons and light cosmic ray nuclei
• Cosmic-Ray Driven Outflows to Mpc Scales from $L_{\ast }$ Galaxies
• Effects of Different Cosmic Ray Transport Models on Galaxy Formation
• A disk-dominated and clumpy circumgalactic medium of the Milky Way seen in X-ray emission
• Abundance and temperature of the outer hot circum-Galactic medium: The SRG/eROSITA view of the soft X-ray background in the eFEDS field
• Hot Extended Galaxy Halos Around Local L* Galaxies From Sunyaev-Zeldovich Measurements
• The hot circumgalactic medium in the eROSITA All-Sky Survey I. X-ray surface brightness profiles
• Widespread Detection of Two Components in the Hot Circumgalactic Medium of the Milky Way
• The hot circumgalactic medium in the eROSITA All-Sky Survey II. Scaling relations between X-ray luminosity and galaxies' mass
• Thermal and chemical properties of the eROSITA bubbles from Suzaku observations
• X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback
• Constraining Cosmic-ray Transport with Observations of the Circumgalactic Medium
• The Impact of Cosmic Rays on the Kinematics of the Circumgalactic Medium
• Synchrotron Emission on FIRE: Equipartition Estimators of Magnetic Fields in Simulated Galaxies with Spectrally-Resolved Cosmic Rays
• The hot circumgalactic medium in the eROSITA All-Sky Survey III. Star-forming and quiescent galaxies
• Why are thermally- and cosmic ray-driven galactic winds fundamentally different?
• Morphology & Environment's Role on the Star Formation Rate -- Stellar Mass Relation in COSMOS from 0 < z < 3.5
• X-raying CAMELS: Constraining Baryonic Feedback in the Circum-Galactic Medium with the CAMELS simulations and eRASS X-ray Observations
• Probing supermassive black hole growth and its dependence on stellar mass and star-formation rate in low-redshift galaxies
• Cosmic Ray Feedback in Massive Halos: Implications for the Distribution of Baryons
• Tracing the Origins of Hot Halo Gas in Milky Way-Type Galaxies with SMUGGLE
• Introducing the Descriptive Parametric Model: Gaseous Profiles for Galaxies, Groups, and Clusters
• IllustrisTNG + Cosmic Rays with a Simple Transport Model: From Dwarfs to L${}^{\star }$ Galaxies

Cited by in corpus (3)

• A systematic study of AGN feedback in a disk galaxy using MACER II: predictions of X-ray surface brightness profiles and comparison with eROSITA observations
• Effects of Varied Cosmic Ray Feedback from AGN on Massive Galaxy Properties
• Time-Dependent Cosmic Ray Halos from Bursty Star Formation and Active Galactic Nuclei: Semi-Analytic Formalism and Galaxy Formation Implications