Figuring Out Gas &amp; Galaxies In Enzo (FOGGIE) V: The Virial Temperature Does Not Describe Gas in a Virialized Galaxy Halo

Lochhaas, Cassandra; Tumlinson, Jason; O'Shea, Brian W.; Peeples, Molly S.; Smith, Britton D.; Werk, Jessica K.; Augustin, Ramona; Simons, Raymond C.

doi:10.48550/arxiv.2102.08393

Cited by 3 publications

(3 citation statements)

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“…Our analysis uses the z = 2, 2.5, and 3 outputs for each of the six FOGGIE halos. As presented in Simons et al (2020), these halos are selected to be "Milky Way-like" in that they are roughly ∼ 10 12 M at z = 0 and have no mergers of mass ratios more than 1:10 after z = 2 (see also Zheng et al 2020 andLochhaas et al 2021 for the full histories and z = 0 properties of the Tempest, Squall, and Maelstrom halos). While the KODIAQ-Z absorbers are not selected to be associated with Milky Way-like halos, galaxy halos of this size account for most of the stellar mass in the universe and therefore most of the chemical enrichment.…”

Section: Motivation and Methodologymentioning

confidence: 99%

KODIAQ-Z: Metals and Baryons in the Cool Intergalactic and Circumgalactic Gas at 2.2

Lehner,

Kopenhafer,

O'Meara

et al. 2021

Preprint

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We present the KODIAQ-Z survey aimed to characterize the cool, photoionized gas at 2.2 z 3.6 in 202 H Iselected absorbers with 14.6 ≤ log N H I < 20, i.e., the gaseous interface between galaxies and the intergalactic medium (IGM). We find that the 14.6 ≤ log N H I < 20 gas at 2.2 z 3.6 can be metal-rich gas (−1.6 [X/H] −0.2) as seen in damped Lyα absorbers (DLAs); it can also be very metal-poor ([X/H] < −2.4) or even pristine gas ([X/H] < −3.8) not observed in DLAs, but commonly observed in the IGM. For 16 < log N H I < 20 absorbers, the frequency of pristine absorbers is about 1%-10%, while for 14.6 ≤ log N H I ≤ 16 absorbers it is 10%-20%, similar to the diffuse IGM. Supersolar gas is extremely rare (< 1%) in this gas. The factor of several thousand spread from the lowest to highest metallicities and large metallicity variations (a factor of a few to > 100) between absorbers separated by less than ∆v < 500 km s −1 imply that the metals are poorly mixed in 14.6 ≤ log N H I < 20 gas. We show that these photoionized absorbers contribute to about 10% of the cosmic baryons and 30% of the cosmic metals at 2.2 z 3.6. We find the mean metallicity increases with N H I , consistent with what is found in z < 1 gas. The metallicity of gas in this column density regime has increased by a factor ∼8 from 2.2 z 3.6 to z < 1, but the contribution of the 14.6 ≤ log N H I < 19 absorbers to the total metal budget of the universe at z < 1 is half that at 2.2 z 3.6, indicating a substantial shift in the reservoirs of metals between these two epochs. We compare the KODIAQ-Z results to FOGGIE cosmological zoom simulations. The simulations show an evolution of [X/H] with N H I similar to our observational results. Very metal-poor absorbers with [X/H] < −2.4 at z ∼ 2-3 in these simulations are excellent tracers of inflows, while higher metallicity absorbers are a mixture of inflows and outflows.

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Section: Motivation and Methodologymentioning

confidence: 99%

KODIAQ-Z: Metals and Baryons in the Cool Intergalactic and Circumgalactic Gas at 2.2

Lehner,

Kopenhafer,

O'Meara

et al. 2021

Preprint

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“…This is why the mass of peak N O VI R200c in the Voit (2019) model is at greater masses than is observed: the mass of T O VI gas is greater around galaxies with T 200c > T O VI than around galaxies with T 200c ≈ T O VI . An analysis of CGM temperatures in high resolution hydrodynamic simulations by Lochhaas et al (2021) finds a similar result: even in virialized galaxy-scale halos, gas on the outskirts of the CGM (i.e., where much of the mass resides) has a characteristic temperature of about 1/2T 200c , rather than T 200c . Halos in which some of the assembly energy is still in the form of coherent, nonthermal motions have an even lower characteristic temperature.…”

Section: What Conditions Does O VI Trace?mentioning

confidence: 78%

The CGM$^2$ Survey: Circumgalactic O VI from dwarf to massive star-forming galaxies

Tchernyshyov,

Werk,

Wilde

et al. 2021

Preprint

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We combine 126 new galaxy-O VI absorber pairs from the CGM 2 survey with 123 pairs drawn from the literature to examine the simultaneous dependence of the column density of O VI absorbers (N O VI ) on galaxy stellar mass, star formation rate, and impact parameter. The combined sample consists of 249 galaxy-O VI absorber pairs covering z = 0-0.6, with host galaxy stellar masses M * = 10 7.8 -10 11.2 M and galaxy-absorber impact parameters R ⊥ = 0-400 proper kiloparsecs. In this work, we focus on the variation of N O VI with galaxy mass and impact parameter among the star-forming galaxies in the sample. We find that the average N O VI within one virial radius of a star-forming galaxy is greatest for star-forming galaxies with M * = 10 9.2 -10 10 M . Star-forming galaxies with M * between 10 8 and 10 11.2 M can explain most O VI systems with column densities greater than 10 13.5 cm −2 . 60% of the O VI mass associated with a star-forming galaxy is found within one virial radius and 35% is found between one and two virial radii. In general, we find that some departure from hydrostatic equilibrium in the CGM is necessary to reproduce the observed O VI amount, galaxy mass dependence, and extent. Our measurements serve as a test set for CGM models over a broad range of host galaxy masses.

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“…This appears to apply all the way from the CGM to the IGrM to the ICM of massive clusters, although the scatter becomes larger with decreasing halo mass. Recently, Lochhaas et al (2021) confirmed for an individual halo that the turbulent energy is a nearly constant fraction of the thermal energy over time.…”

Section: Discussionmentioning

confidence: 96%

Turbulence in the intragroup and circumgalactic medium

Schmidt

Grete

2021

A&A

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Context. In massive objects, such as galaxy clusters, the turbulent velocity dispersion, σturb, is tightly correlated to both the object mass, M, and the thermal energy. Aims. Here, we investigate whether these scaling laws extend to lower-mass objects in dark-matter filaments. Methods. We perform a cosmological zoom-in simulation of a filament using an adaptive filtering technique for the resolved velocity component and a subgrid-scale model to account for the unresolved component. We then compute the mean turbulent and thermal energies for all halos in the zoom-in region and compare different definitions of halo averages. Averaging constrained by density and temperature thresholds is favored over averages solely based on virial spheres. Results. We find no clear trend for the turbulent velocity dispersion versus halo mass, but significant correlation and a scaling law with exponent α ∼ 0.5 between the turbulent velocity dispersion and thermal energy that agrees with a nearly constant turbulent Mach number, similar to more massive objects. Conclusions. We conclude that the self-similar energetics proposed for galaxy clusters extends down to the circumgalactic medium of individual galaxies.

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Figuring Out Gas & Galaxies In Enzo (FOGGIE) V: The Virial Temperature Does Not Describe Gas in a Virialized Galaxy Halo

Cited by 3 publications

References 105 publications

KODIAQ-Z: Metals and Baryons in the Cool Intergalactic and Circumgalactic Gas at 2.2

KODIAQ-Z: Metals and Baryons in the Cool Intergalactic and Circumgalactic Gas at 2.2

The CGM$^2$ Survey: Circumgalactic O VI from dwarf to massive star-forming galaxies

Turbulence in the intragroup and circumgalactic medium

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