Stacking of DESI quasar spectra reveals strong, localized Hα emission aligned with radio jet axes around radio galaxies, indicating anisotropic jet-CGM interaction.
hub Mixed citations
Title resolution pending
Mixed citation behavior. Most common role is background (60%).
49
Pith papers citing it
1,013
external citations · Crossref
Background
60% of classified citations
abstract
The gas surrounding galaxies outside their disks or interstellar medium and inside their virial radii is known as the circumgalactic medium (CGM). In recent years this component of galaxies has assumed an important role in our understanding of galaxy evolution owing to rapid advances in observational access to this diffuse, nearly invisible material. Observations and simulations of this component of galaxies suggest that it is a multiphase medium characterized by rich dynamics and complex ionization states. The CGM is a source for a galaxy's star-forming fuel, the venue for galactic feedback and recycling, and perhaps the key regulator of the galactic gas supply. We review our evolving knowledge of the CGM with emphasis on its mass, dynamical state, and coevolution with galaxies. Observations from all redshifts and from across the electromagnetic spectrum indicate that CGM gas has a key role in galaxy evolution. We summarize the state of this field and pose unanswered questions for future research.
hub tools
citation-role summary
background 5
citation-polarity summary
roles
background 5representative citing papers
Forward modeling of 90 localized FRBs from DSA and ASKAP yields n_z = 1.62^{+1.48}_{-1.57} for DM_host(z) ∝ (1+z)^{n_z}, excluding n_z=0 at 1σ.
JWST observations of absorption lines in z~3 galaxies show inclination-dependent gas flows, with face-on systems exhibiting stronger outflows and inclined systems more inflows.
JWST spectra of six z=5-9 galaxies show low-ionization covering fractions of 0.2-0.9 and diverse kinematics including blueshifted outflows, indicating heterogeneous multiphase ISM.
Stacked JWST spectra show weak MZR slope evolution to z~5 with declining normalization, steeper MZR beyond z~5, and emerging shallow FMR anti-correlation by z~5.
In the IllustrisTNG model, CGM gas around z=1 galaxies mixes quickly and separates into cold inner and warm-hot outer phases within 500 Myr due to feedback, with kinematic decorrelation over 400 Myr and ion-specific phases lasting different durations.
Efficient cosmic-ray transport in CR-pressure-dominated CGM simulations produces stronger cool-gas absorption (MgII, SiII) and covering fractions matching star-forming galaxies, while slow transport underproduces them.
The GWTC-4 BNS merger rate is 28–300 Gpc^-3 yr^-1, a factor of 3.6–18 lower than the cosmological short GRB rate and 2.3–5.1 lower than Galactic DNS estimates, implying an emerging tension among neutron-star merger probes.
Galaxies hosting co-spatial radio sources show roughly twice the Compton-y signal at fixed stellar mass compared to those without, persisting to halo scales, with two competing explanations: higher halo mass or AGN thermal energy injection.
In idealised driven subsonic MHD boxes, Arepo, Athena and Ramses all show dynamo amplification whose residual differences are explained by numerical diffusion, with no systematic advantage of constrained transport.
Adding a fitted radio-emission component to tSZ×galaxy cross-spectra removes an apparent negative small-scale signal and yields spectra consistent with a standard halo model (9.5–11σ BIC preference for the radio term).
COLIBRE simulations find the galaxy gas-phase MZR already in place at z≈10 with little evolution until z≈5, then shallowens at low z, with high-mass turnover set by AGN feedback and low-mass end by core-collapse supernovae.
Radio observations of Faraday rotation in CARLA J1510+5958 at z=1.72 yield a lower limit of 0.4 μG on the average magnetic field strength in the proto-intra-cluster medium.
Forecasts ~thousands of FRB-QSO pairs at <10' separation by 2035 for CGM, cosmic web, and Milky Way halo studies with HST/COS.
A 4.5σ excess RM dispersion of 4.13 ± 0.91 rad m^{-2} is found in 191 Mg II sightlines versus controls, implying model-dependent CGM magnetic fields of 0.4-0.8 μG at projected radii 20-150 kpc and z~1.14.
Spatially resolved observations of z~0.1 galaxies show Mg II absorption outflow velocities are systematically higher than Hα emission velocities by ~0.4 dex while maintaining similar correlations with star formation rate and surface density.
ArkenstoneBH is a new subgrid model for the hot phase of black hole feedback that, in isolated galaxy tests, suppresses star formation by counteracting gas inflows from the circumgalactic medium.
DESI DR2 identifies 50,088 galaxies with moderate and 27,420 with strong evidence for down-the-barrel NaI D absorption revealing inflows at ~20 km/s and multiple accretion pathways at z < 0.6.
New VLT observations of He I* absorbers yield a primordial ³He/⁴He ratio of (1.15^{+0.24}_{-0.21})×10^{-4} consistent with standard Big Bang nucleosynthesis, plus an updated stellar yield scaling factor.
Lya nebulae around unobscured quasars are more extended, asymmetric, and show steeper velocity dispersion declines than those around obscured quasars, supporting an evolutionary AGN model at cosmic noon.
TNG50 MW analogues reproduce global soft X-ray luminosity, inner surface brightness, emission measure and O VII absorption but show too-steep radial decline in X-ray brightness and 65% lower O VIII absorption than observed, indicating overly central feedback.
Bursty stellar feedback produces systematically flatter metallicity gradients than smooth feedback in high-redshift galaxies across multiple simulation suites.
Analysis of JWST/NIRSpec Prism spectra for 25 z>=10 galaxies finds burstiness correlates with strong UV lines, short depletion times, and DLA-induced redshift biases of 0.39 and 0.14 with marginal impact on UV luminosity density.
FIRE-3 cosmological simulations of Seyfert galaxies produce episodic AGN feedback and gas clearing but no clear anti-correlation between nuclear gas concentration and AGN luminosity, highlighting timing mismatches with observations.
citing papers explorer
-
Lighting Up the CGM: Strong, Jet-Aligned $H\alpha$ Emission around Radio Galaxies
Stacking of DESI quasar spectra reveals strong, localized Hα emission aligned with radio jet axes around radio galaxies, indicating anisotropic jet-CGM interaction.
-
Fast Radio Bursts probe Galaxy Evolution: Evidence and implications of a redshift-dependent FRB host DM
Forward modeling of 90 localized FRBs from DSA and ASKAP yields n_z = 1.62^{+1.48}_{-1.57} for DM_host(z) ∝ (1+z)^{n_z}, excluding n_z=0 at 1σ.
-
Unprecedented Constraints on Gas Flows at High Redshift Using Deep JWST/NIRSpec Observations from the LyC22, EXCELS, and AURORA Surveys
JWST observations of absorption lines in z~3 galaxies show inclination-dependent gas flows, with face-on systems exhibiting stronger outflows and inclined systems more inflows.
-
JWST absorption line spectroscopy with SPURS: ISM covering fractions and kinematics in individual galaxies at $z=5-9$
JWST spectra of six z=5-9 galaxies show low-ionization covering fractions of 0.2-0.9 and diverse kinematics including blueshifted outflows, indicating heterogeneous multiphase ISM.
-
The JADES Mass-Metallicity and Fundamental Metallicity Relations at $z\gtrsim2$ Using New High-Redshift Metallicity Calibrations
Stacked JWST spectra show weak MZR slope evolution to z~5 with declining normalization, steeper MZR beyond z~5, and emerging shallow FMR anti-correlation by z~5.
-
The Thermodynamic and Kinematic Evolution of Circumgalactic Gas around $z=1$ in the IllustrisTNG model
In the IllustrisTNG model, CGM gas around z=1 galaxies mixes quickly and separates into cold inner and warm-hot outer phases within 500 Myr due to feedback, with kinematic decorrelation over 400 Myr and ion-specific phases lasting different durations.
-
CRexit observed: probing cosmic ray transport in the circumgalactic medium with absorption line spectra
Efficient cosmic-ray transport in CR-pressure-dominated CGM simulations produces stronger cool-gas absorption (MgII, SiII) and covering fractions matching star-forming galaxies, while slow transport underproduces them.
-
Implications of low neutron star merger rates for gamma-ray bursts, r-process production and Galactic double neutron stars
The GWTC-4 BNS merger rate is 28–300 Gpc^-3 yr^-1, a factor of 3.6–18 lower than the cosmological short GRB rate and 2.3–5.1 lower than Galactic DNS estimates, implying an emerging tension among neutron-star merger probes.
-
Thermal Sunyaev-Zel'dovich Measurements of Locally Bright Galaxies with ACT DR6: Radio Source Contamination and Excess Compton-y Signal
Galaxies hosting co-spatial radio sources show roughly twice the Compton-y signal at fixed stellar mass compared to those without, persisting to halo scales, with two competing explanations: higher halo mass or AGN thermal energy injection.
-
A comparison of numerical schemes for driven subsonic MHD turbulence
In idealised driven subsonic MHD boxes, Arepo, Athena and Ramses all show dynamo amplification whose residual differences are explained by numerical diffusion, with no systematic advantage of constrained transport.
-
Thermal Sunyaev-Zel'dovich cross-correlations with unWISE galaxies: disentangling radio contamination, dust properties, and electron pressure
Adding a fitted radio-emission component to tSZ×galaxy cross-spectra removes an apparent negative small-scale signal and yields spectra consistent with a standard halo model (9.5–11σ BIC preference for the radio term).
-
The evolution of the galaxy gas-phase mass-metallicity relation from $z=15$ to $z=0$ in the COLIBRE cosmological simulations
COLIBRE simulations find the galaxy gas-phase MZR already in place at z≈10 with little evolution until z≈5, then shallowens at low z, with high-mass turnover set by AGN feedback and low-mass end by core-collapse supernovae.
-
Magnetic fields at the dawn of structure formation I. The CARLA J1510+5958 proto-cluster
Radio observations of Faraday rotation in CARLA J1510+5958 at z=1.72 yield a lower limit of 0.4 μG on the average magnetic field strength in the proto-intra-cluster medium.
-
A Decade to Map the Diffuse Universe: FRB-QSO Pairs with HST/COS Spectroscopy
Forecasts ~thousands of FRB-QSO pairs at <10' separation by 2035 for CGM, cosmic web, and Milky Way halo studies with HST/COS.
-
Magnetised CGM Gas at z~1 revealed by SPICE-RACS
A 4.5σ excess RM dispersion of 4.13 ± 0.91 rad m^{-2} is found in 191 Mg II sightlines versus controls, implying model-dependent CGM magnetic fields of 0.4-0.8 μG at projected radii 20-150 kpc and z~1.14.
-
Differences between emission and absorption tracers of spatially resolved outflows in clumpy z ~ 0.1 star-forming galaxies
Spatially resolved observations of z~0.1 galaxies show Mg II absorption outflow velocities are systematically higher than Hα emission velocities by ~0.4 dex while maintaining similar correlations with star formation rate and surface density.
-
ArkenstoneBH. A model for high-specific energy black hole feedback in cosmological simulations
ArkenstoneBH is a new subgrid model for the hot phase of black hole feedback that, in isolated galaxy tests, suppresses star formation by counteracting gas inflows from the circumgalactic medium.
-
Peering down the barrel with DESI DR2: 10 000+ inflows at $z$ < 0.6 reveal how galaxies accrete cold gas
DESI DR2 identifies 50,088 galaxies with moderate and 27,420 with strong evidence for down-the-barrel NaI D absorption revealing inflows at ~20 km/s and multiple accretion pathways at z < 0.6.
-
Towards a measurement of the primordial helium isotope ratio
New VLT observations of He I* absorbers yield a primordial ³He/⁴He ratio of (1.15^{+0.24}_{-0.21})×10^{-4} consistent with standard Big Bang nucleosynthesis, plus an updated stellar yield scaling factor.
-
Constraining the nature of active galactic nuclei through circumgalactic Lya emission at z=2-3
Lya nebulae around unobscured quasars are more extended, asymmetric, and show steeper velocity dispersion declines than those around obscured quasars, supporting an evolutionary AGN model at cosmic noon.
-
Probing the Hot Gaseous Halos of Milky Way-like Galaxies in the TNG50 simulation
TNG50 MW analogues reproduce global soft X-ray luminosity, inner surface brightness, emission measure and O VII absorption but show too-steep radial decline in X-ray brightness and 65% lower O VIII absorption than observed, indicating overly central feedback.
-
Metallicity Gradients in Modern Cosmological Simulations II: The Role of Bursty Versus Smooth Feedback at High-Redshift
Bursty stellar feedback produces systematically flatter metallicity gradients than smooth feedback in high-redshift galaxies across multiple simulation suites.
-
JWST spectroscopy of galaxies at $z>10$: Damped Ly$\alpha$ absorbers reveal efficient star formation and hidden redshift biases
Analysis of JWST/NIRSpec Prism spectra for 25 z>=10 galaxies finds burstiness correlates with strong UV lines, short depletion times, and DLA-induced redshift biases of 0.39 and 0.14 with marginal impact on UV luminosity density.
-
Investigating black hole accretion and feedback self-regulation in Seyfert galaxies using the FIRE-3 cosmological hydrodynamic simulations
FIRE-3 cosmological simulations of Seyfert galaxies produce episodic AGN feedback and gas clearing but no clear anti-correlation between nuclear gas concentration and AGN luminosity, highlighting timing mismatches with observations.
-
The dependence of Circumgalactic Medium properties on halo assembly histories in the IllustrisTNG simulations
TNG50 simulation analysis finds early-forming halos show higher stellar mass, metallicity, lower CGM gas mass and sSFR at z=0, with mass-dependent CGM metallicity reversal and cold-gas kinematics differences.
-
A First Measurement of Circumgalactic Dust Reddening from Only 4.6 deg$^2$ of the Rubin Observatory's DP1
The first circumgalactic dust reddening measurement from Rubin DP1 data finds A_V proportional to r_perp to the -1.8 power within 120 kpc, consistent with prior SDSS/KiDS/DES results despite 1000x smaller area and fainter foreground sample.
-
Radial gradients revealed by mutliscale outflows from down-the-barrel spectroscopy toward a quasar at redshift 3.4
Spectroscopy of a z=3.409 quasar detects three freely expanding outflows with radial N/C gradients, indicating a transition from ejective to regulative feedback.
-
Cooler Phases of the Circumgalactic Medium Are More Centrally Concentrated: Constraints from Multiphase Absorption Lines
Cooler CGM phases traced by Ca II and Mg II exhibit steeper radial equivalent width profiles than the warmer C IV phase, with host-type differences and stellar-mass dependence.
-
Connecting CGM enrichment with Lyman alpha emitters at 2.9 < z < 6.7
Blind MUSE search detects 156 LAEs at 2.9<z<6.7 with 34 C IV and 14 Mg II absorber associations, indicating low-mass galaxies enrich the CGM.
-
The Simulated Oxygen Shortage (SOS): Mapping the Missing OVI in Simulated Dwarf Galaxies to Subgrid Physics
The paper identifies underproduction of oxygen in low-mass simulated dwarf galaxies as the likely cause of missing OVI in the CGM, based on comparisons across two simulation suites.
-
Non-Equilibrium Ionisation in Photoionised Haloes: Implications for Shock Stability and Absorption-Line Signatures
UV background suppresses NEI in galaxy haloes, restoring equilibrium shock thresholds and producing extended absorption columns for OVI, CIV, and HI beyond the virial radius.
-
Analysis of synthetic OVI absorption associated with galaxy groups in SIMBA and TNG50 simulations
Both SIMBA and TNG50 simulations underpredict OVI covering fractions around galaxy groups compared to observations, with most absorbers being gravitationally bound.
-
The Qz5 Survey (II): Metallicity Evolution of Damped Ly{\alpha} Systems Out to z$\sim$5
New observations of high-redshift DLAs show that the metallicity of neutral hydrogen gas drops sharply at z approximately 5.
-
The 256-antenna Coherent All-Sky Monitor
CASM-256 is a new 256-antenna radio array at Owens Valley that uses real-time digital beamforming to search for fast radio bursts and galactic transients over a huge sky area.
-
Too Big to Quench? I. Constraining ISM Stripping of Dwarf Satellites in Milky Way-like Halos
Simulations constrain the mass scale for efficient ISM stripping of dwarf satellites to M_star ≲ 10^7 M_sun in MW-like halos, 0.5-1 dex below observed values, indicating additional quenching mechanisms are needed.
-
Galactic Cosmic Ray Transport in the Giant Circumgalactic Medium Halo
Galactic cosmic rays in a giant CGM halo develop an extended 1/r spatial tail and broader age distribution while remaining consistent with secondary-to-primary ratio data.
-
The X-ray-to-UV relation does not evolve in homogeneous quasar samples
A bias-controlled quasar sample of ~2000 objects demonstrates that the X-ray-to-UV luminosity relation remains constant from redshift 0.7 to 5.
-
GREX-PLUS Science Book v2
A mission-proposal science book forecasting observational yields for a proposed JAXA 2–18 µm infrared space telescope; no new measurement or derivation is presented.
-
The Case for Astrons
A sparse population of primordial charged compact objects is hypothesized with specific parameters and shown to face severe plasma-screening and neutralization constraints while failing to produce late-time acceleration in the homogeneous FLRW approximation.
-
Low-ionization Metal Absorption at $0.7 \lesssim z \lesssim 2$ Confronting Cosmological Simulations with Observations
IllustrisTNG with a uniform UVB reproduces observed MgI, MgII and FeII column-density PDFs and low-EW MgII incidence but underestimates the number of strong MgII systems and fails to capture their rise toward z~2.
-
Modeling the Accretion of High-Velocity Clouds from a Rotating Halo
Low-angular-momentum test-particle models of HVCs originating at tens of kpc in a rotating halo reproduce observed kinematics and imply an accretion rate of several solar masses per year sufficient for long-term star formation.
-
Cosmic-Ray Spectra and Metal Budget Regulated by the Galactic Wind
Galactic wind advection with a peak velocity of ~700 km/s reproduces cosmic ray spectral hardening from hundreds of GV and softening from a few TV without diffusion breaks, predicts a hard spectrum (index ~2) at 3-5 kpc altitudes consistent with Fermi bubbles, and shows the wind maintains disk metal
-
Astronomical Advantages of a Boost Mission to Facilitate HST Science into the 2030s: Imaging the Circumgalactic Medium of Galaxies
The paper advocates for boosting HST's orbit to enable unique UV emission-line imaging of the circumgalactic medium, delivering the first statistical constraints on warm-hot gas and aiding target selection for the future Habitable Worlds Observatory.
-
Simulation of non X-ray background for the DIffuse X-ray Explorer (DIXE) mission
DIXE NXB averages 4.46e-2 counts s^-1 cm^-2 keV^-1 at the geomagnetic equator under solar minimum, dominated by cosmic-proton-induced particles, rising to 1.55e-1 at higher latitudes, with SAA delayed background negligible after ~5 minutes.
-
Fast Radio Bursts as Cosmological Probes
FRBs serve as cosmological probes via dispersion measure, scattering, and Faraday rotation to constrain baryon distribution, expansion history, magnetic fields, and fundamental physics effects.
-
A series of unfortunate events: CHIME/FRB misclassification of a Galactic pulsar as a periodic fast radio burst
A reported periodic fast radio burst is reclassified as Galactic pulsar emission due to CHIME calibration and beam-pointing error.
-
Revealing Cosmic Ecosystems with the Hubble Space Telescope in 2030s and Beyond
HST UV spectroscopy is presented as the unique tool for probing multiphase gas at the disk-CGM interface to understand how galaxies acquire fuel, recycle metals, and drive feedback.
- A Comprehensive Study of Morphology and Kinematics in Extended Nebulae Around UV Luminous Quasars at $z\approx1$
- From Clumps to Sheets: Geometry Controls the Temperature PDF of Multi-Phase Gas