Kinematics of the O vi Circumgalactic Medium: Halo Mass Dependence and Outflow Signatures

Ng, Mason; Nielsen, Nikole M.; Kacprzak, Glenn G.; Pointon, Stephanie K.; Muzahid, Sowgat; Churchill, Christopher W.; Charlton, Jane C.

doi:10.3847/1538-4357/ab48eb

Cited by 19 publications

(26 citation statements)

References 93 publications

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“…Interestingly, they did not detect C in groups that include more than seven galaxies. It was also shown that O absorption within galaxy groups exhibits lower column densities and lower velocity spreads when compared to isolated environments (Stocke et al 2013;Pointon et al 2017;Ng et al 2019). This is consistent with cosmological simulations that show that since the virial temperature increases with halo mass, group environments ionize a larger fraction of oxygen to higher levels, which results in a lower ionization fraction of O compared to isolated galaxies (Oppenheimer et al 2016).…”

Section: Introductionsupporting

confidence: 79%

“…The O absorption is kinematically spread over Δ 90 = 419 km s −1 , which is among the four systems with the largest kinematic spreads at < 1 (M15, and references therein). Ng et al (2019) found that O absorption along the minor axis of edge- Oppenheimer et al (2016) and Ng et al (2019). Orange points are the simulated galaxies, larger solid blue diamonds represent the group environments, and the smaller open blue diamonds refer to isolated galaxies.…”

Section: Mid-to High-ionization Phasesmentioning

confidence: 99%

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Disentangling the multiphase circumgalactic medium shared between a dwarf and a massive star-forming galaxy at z∼0.4

Nateghi

Kacprzak

Nielsen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The multi-phase circumgalactic medium (CGM) arises within the complex environment around a galaxy, or collection of galaxies, and possibly originates from a wide range of physical mechanisms. In this paper, we attempt to disentangle the origins of these multi-phase structures and present a detailed analysis of the quasar field Q0122−003 field using Keck/KCWI galaxy observations and HST/COS spectra probing the CGM. Our re-analysis of this field shows that there are two galaxies associated with the absorption. We have discovered a dwarf galaxy, G_27kpc (M⋆ = 108.7 M⊙), at z = 0.39863 that is 27 kpc from the quasar sightline. G_27kpc is only +21 km s−1 from a more massive (M⋆ = 1010.5 M⊙) star-forming galaxy, G_163kpc, at an impact parameter of 163 kpc. While G_163kpc is actively forming stars (SFR = 6.9 M⊙ yr−1), G_27kpc has a low star-formation rate (SFR = 0.08 ± 0.03 M⊙ yr−1) and star formation surface density (ΣSFR = 0.006 M⊙ kpc−2 yr−1), implying no active outflows. By comparing galaxy SFRs, kinematics, masses and distances from the quasar sightline to the absorption kinematics, column densities and metallicities, we have inferred the following: (1) Part of the low-ionization phase has a metallicity and kinematics consistent with being accreted onto G_27kpc. (2) The remainder of the low ionization phase has metallicities and kinematics consistent with being intragroup gas being transferred from G_27kpc to G_163kpc. (3) The high ionization phase is consistent with being produced solely by outflows originating from the massive halo of G_163kpc. Our results demonstrate the complex nature of the multi-phase CGM, especially around galaxy groups, and that detailed case-by-case studies are critical for disentangling its origins.

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Section: Introductionsupporting

confidence: 79%

Section: Mid-to High-ionization Phasesmentioning

confidence: 99%

Disentangling the multiphase circumgalactic medium shared between a dwarf and a massive star-forming galaxy at z∼0.4

Nateghi

Kacprzak

Nielsen

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…It is plausible that G1547 is low star-forming, green-valley galaxy that is becoming quenched due to a lack of CGM. massive systems have hot virial temperatures and there is little O to be found, since oxygen resides in even higher ionisation phases (Oppenheimer et al 2016;Ng et al 2019). Burchett et al (2016) found similar results for C , whereby the detection rate is lower for galaxies found in over-densities and/or residing in groups with dark matter halo masses of h > 10 12.5 M .…”

Section: Discussionmentioning

confidence: 68%

“…The only ion where upper limits are less common at low impact parameter is O as there are only 9 non-absorbing galaxies within 100 kpc. It has been noted that a lack of O could either be attributed to the lack of star formation Tumlinson et al (2011), or due to a halo mass and O column density dependence (Ng et al 2019;Oppenheimer et al 2016). We next explore additional measurable properties of G1547 with the goal of inferring why it lacks significant absorption.…”

Section: Resultsmentioning

confidence: 99%

“…HST/COS quasar spectra were obtained using the G130M (exposure time of 9841 seconds), G160M (10,254 seconds) and G185M (2609 seconds) as part of the "Multiphase Galaxy Halos" Survey [from PID 13398 (Kacprzak et al 2015;Muzahid et al 2015Muzahid et al , 2016Nielsen et al 2017;Pointon et al 2017;Kacprzak et al 2019a,b;Ng et al 2019;Pointon et al 2019Pointon et al , 2020]. These spectra cover a large range of metal and hydrogen absorption lines at the redshift of G1547.…”

Section: Quasar Hst/cos Spectramentioning

confidence: 99%

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Evidence for galaxy quenching in the green valley caused by a lack of a circumgalactic medium

Kacprzak

Nielsen

Nateghi

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The relationship between a galaxy’s properties and its circumgalactic medium (CGM) provides a unique view of how galaxies evolve. We present an interesting edge-on (i = 86 degrees) disk galaxy (G1547) where the CGM is probed by a background quasar at a distance of 84 kpc and within 10 degrees of the galaxy major axis. G1547 does not have any detectable CGM absorption down to stringent limits, covering H i (EWr<0.02 Å, log(N(H i)/cm−2)<12.6) and a range of low and high ionisation absorption lines (O i, C ii, N ii, Si ii, C iii, N iii, Si iii, C iv, Si iv, N v and O vi). This system is rare, given the covering fraction of $1.00_{-0.04}^{+0.00}$ for sub-L* galaxies within 50-100 kpc of quasar sightlines. G1547 has a low SFR (1.1 M⊙ yr−1), SSFR (1.5 × 10−10 yr−1) and ΣSFR (0.06 M⊙ yr−1 kpc−2) and does not exhibit AGN or star-formation driven outflows. Compared to the general population of galaxies, G1547 is in the green valley and has an above average metallicity with a negative gradient. When compared to other H i absorption-selected galaxies, we find that quiescent galaxies with log(SSFR/yr−1) < −11 have a low probability (4/12) of possessing detectable H i in their CGM, while all galaxies (40/40) with log(SSFR/yr−1) > −11 have H i absorption. We conclude that SSFR is a good indicator of the presence of H i CGM. Interestingly however, G1547 is the only galaxy with log(SSFR/yr−1) > −11 that has no detectable CGM. Given the properties of G1547, and its absent CGM, it is plausible that G1547 is undergoing quenching due to a lack of accreting fuel for star-formation, with an estimated quenching timescale of 4 ± 1 Gyr. G1547 provides a unique perspective into the external mechanisms that could explain the migration of galaxies into the green valley.

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Thermal instability in the CGM of L⋆ galaxies: testing ‘precipitation’ models with the FIRE simulations

Esmerian

Kravtsov

Hafen

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We examine the thermodynamic state and cooling of the low-z Circum-Galactic Medium (CGM) in five FIRE-2 galaxy formation simulations of Milky Way-mass galaxies. We find that the CGM in these simulations is generally multiphase and dynamic, with a wide spectrum of largely nonlinear density perturbations sourced by the accretion of gas from the Inter-Galactic Medium (IGM) and outflows from both the central and satellite galaxies. We investigate the origin of the multiphase structure of the CGM with a particle tracking analysis and find that most of the low entropy gas has cooled from the hot halo as a result of thermal instability triggered by these perturbations. The ratio of cooling to free-fall timescales tcool/tff in the hot component of the CGM spans a wide range ∼1 − 100 at a given radius, but exhibits approximately constant median values ∼5 − 20 at all radii 0.1Rvir < r < Rvir. These are similar to the ≈10 − 20 value typically adopted as the thermal instability threshold in ‘precipitation’ models of the ICM. Consequently, a one-dimensional model based on the assumption of a constant tcool/tff and hydrostatic equilibrium approximately reproduces the number density and entropy profiles of each simulation, but only if it assumes the metallicity profile and temperature boundary condition taken directly from the simulation. We explicitly show that the tcool/tff value of a gas parcel in the hot component of the CGM does not predict its probability of subsequently accreting on to the central galaxy. This suggests that the value of tcool/tff is a poor predictor of thermal stability in gaseous haloes in which large-amplitude density perturbations are prevalent.

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Kinematics of the O vi Circumgalactic Medium: Halo Mass Dependence and Outflow Signatures

Cited by 19 publications

References 93 publications

Disentangling the multiphase circumgalactic medium shared between a dwarf and a massive star-forming galaxy at z∼0.4

Disentangling the multiphase circumgalactic medium shared between a dwarf and a massive star-forming galaxy at z∼0.4

Evidence for galaxy quenching in the green valley caused by a lack of a circumgalactic medium

Thermal instability in the CGM of L⋆ galaxies: testing ‘precipitation’ models with the FIRE simulations

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