A panoramic view of the circumgalactic medium in the photoionized precipitation model

Abstract

We consider a model of the circumgalactic medium (CGM) in which feedback maintains a constant ratio of cooling time to freefall time throughout the halo, so that the entire CGM is marginally unstable to multiphase condensation. This 'precipitation model' is motivated by observations of multiphase gas in the cores of galaxy clusters and the halos of massive ellipticals. We derive from the model density and temperature profiles for the CGM around galaxies with masses similar to the Milky Way. After taking into consideration the geometrical position of our solar system in the Milky Way, we show that the CGM model is consistent with observed OVI, OVII, and OVIII column densities only if temperature fluctuations with a log-normal dispersion ${\sigma }_{\ln T}\sim 0.6$-$1.0$ are included. We show that OVI column densities observed around star-forming galaxies require systematically greater values of ${\sigma }_{\ln T}$ than around passive galaxies, implying a connection between star formation in the disk and the state of the CGM. Photoionization by an extra-galactic UV background does not significantly change these CGM features for galaxies like the Milky Way but has much greater and significant effects on the CGM of lower-mass galaxies.

12 pages, 10 figures, 1 table, Accepted for publication in MNRAS

References in corpus (12)

• The Circumgalactic Medium
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Cold gas accretion in galaxies
• The COS-Halos Survey: Metallicities in the Low-Redshift Circumgalactic Medium
• The COS-Dwarfs Survey: The Carbon Reservoir Around sub-L* Galaxies
• The COS-Halos Survey: Origins of the Highly Ionized Circumgalactic Medium of Star-Forming Galaxies
• Cooling Time, Freefall Time, and Precipitation in the Cores of ACCEPT Galaxy Clusters
• The extent of chemically enriched gas around star-forming dwarf galaxies
• XMM-Newton Survey of Local O VII Absorption Lines in the Spectra of Active Galactic Nuclei
• Time-Dependent Cooling in Photoionized Plasma
• Thermal Instability in the CGM of $L_{\star }$ Galaxies: Testing "Precipitation" Models with the FIRE Simulations
• A Graphical Interpretation of Circumgalactic Precipitation

Cited by in corpus (2)

• The CGM${}^2$ Survey: Circumgalactic O VI from dwarf to massive star-forming galaxies
• Constraints on cosmic rays in the Milky Way circumgalactic medium from OVIII observations