MAGiiCAT IV. Kinematics of the circumgalactic medium and evidence for quiescent evolution around red galaxies

Journal Article · Sat Feb 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/818/2/171· OSTI ID:22886998

Nielsen, Nikole M.; Kacprzak, Glenn G.; Murphy, Michael T. ^[1]; Churchill, Christopher W.

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1. Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122 (Australia)

The equivalent widths of Mg II absorption in the circumgalactic medium (CGM) trace the global star formation rate up to z < 6, are larger for star-forming galaxies than passively evolving galaxies, and decrease with increasing distance from the galaxy. We delve further into the physics involved by investigating gas kinematics and cloud column density distributions as a function of galaxy color, redshift, and projected distance from the galaxy (normalized by galaxy virial radius, D/R{sub vir}). For 39 isolated galaxies at 0.3 < z{sub gal} < 1.0, we have detected Mg II absorption in high-resolution (Δv ≃ 6.6 km s{sup −1}) spectra of background quasars within a projected distance of 7 < D < 190 kpc. We characterize the absorption velocity spread using pixel-velocity two-point correlation functions. Velocity dispersions and cloud column densities for blue galaxies do not differ with redshift nor with D/R{sub vir}. This suggests that outflows continually replenish the CGM of blue galaxies with high velocity dispersion, large column density gas out to large distances. Conversely, absorption hosted by red galaxies evolves with redshift where the velocity dispersions (column densities) are smaller (larger) at z{sub gal} < 0.656. After taking into account larger possible velocities in more massive galaxies, we find that there is no difference in the velocity dispersions or column densities for absorption hosted by red galaxies with D/R{sub vir}. Thus, a lack of outflows in red galaxies causes the CGM to become more quiescent over time, with lower velocity dispersions and larger column densities toward lower z{sub gal}. The quenching of star formation appears to affect the CGM out to D/R{sub vir} = 0.75.

• OSTI ID: 22886998
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 818; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
CORRELATION FUNCTIONS
COSMIC DUST
DISPERSIONS
DISTANCE
DISTRIBUTION
GALACTIC EVOLUTION
GALAXIES
INTERGALACTIC SPACE
MAGNESIUM
QUASARS
RED SHIFT
RESOLUTION
SPECTRA
STAR EVOLUTION
STARS
VELOCITY