Angular momentum-related probe of cold gas deficiencies

Abstract

Recent studies of neutral atomic hydrogen (H i) in nearby galaxies found that all field disk galaxies are H i saturated, in that they carry roughly as much H i as permitted before this gas becomes gravitationally unstable. By taking this H i saturation for granted, the atomic gas fraction f atm of galactic disks can be predicted as a function of the stability parameter q = jσ/(GM), where M and j are the baryonic mass and specific angular momentum of the disk and σ is the H i velocity dispersion (Obreschkow et al. 2016). The log-ratio ∆ f q between this predictor and the observed atomic fraction can be seen as a physically motivated 'H i deficiency'. While field disk galaxies have ∆ f q ≈ 0, objects subject to environmental removal of H i are expected to have ∆ f q > 0. Within this framework, we revisit the H i deficiencies of satellite galaxies in the Virgo cluster and in clusters of the EAGLE simulation. We find that observed and simulated cluster galaxies are H i deficient and that ∆ f q slightly increases when getting closer to the cluster centres. The ∆ f q values are similar to traditional H i deficiency estimators, but ∆ f q is more directly comparable between observations and simulations than morphology-based deficiency estimators. By tracking the simulated H i deficient cluster galaxies back in time, we confirm that ∆ f q ≈ 0 until the galaxies first enter a halo with M halo > 10 13 M , at which moment they quickly lose H i by environmental effects. Finally, we use the simulation to investigate the links between ∆ f q and quenching of star formation.

The Dawes Review 9: The role of cold gas stripping on the star formation quenching of satellite galaxies

“…While this is arguably a more physically motivated definition of HI deficiency (but see also Romeo & Mogotsi 2018 for some potential limitations of this approach), the basic assumptions are the same behind the original HG84 definition. Indeed, Li et al (2020) show that (at least in the case of galaxies in the Virgo cluster) the two definitions provide remarkably consistent results.…”

“…In recent years, independent works have put forward a new definition of gas deficiency based on the angular momentum properties of galaxies. This idea has been proposed by a few authors throughout the last few decades (e.g., Zasov & Rubtsova 1989;Safonova 2011) and most recently expanded by Li et al (2020). Their approach is based on the assumption that, for a flat exponential disc with circular rotation, the maximum allowed, stable value of gas fraction strongly depends on the mass and kinematics of the disc.…”

“…One of the key reasons why the above limitations have rarely been discussed in the literature is that we are still lacking galaxy samples that simultaneously cover wide ranges of environments (to include both gas-rich and gas-deficient systems), are representative of the local galaxy population (to calibrate reliable scaling relations) and for which sizes, luminosities and angular momentum can be homogeneously estimated (see however HG84, Cortese et al 2011;Teimoorinia, Ellison, & Patton 2017;Li et al 2020 for discussions on different gas deficiency definitions and gas predictors in general).…”

The MUSEHubbleUltra Deep Field Survey

“…In a Λ cold dark matter (ΛCDM) universe, baryons cool, fall inwards, and form centrifugally supported disks in the centers of halos. The specific angular momentum (sAM) sets the pressure, instabilities, gas fractions (Obreschkow et al 2016;Romeo & Mogotsi 2018;Romeo 2020;Li et al 2020), and most importantly determines the disk properties, such as size (e.g., White & Rees 1978;Fall & Efstathiou 1980;Fall 1983;Mo et al 1998;Dalcanton et al 1997;van den Bosch et al 2003;Dutton & van den Bosch 2009;Somerville et al 2018). As disks evolve from z = 2 to the present, they must grow from a vast reservoir of corotating cold accreting material in the circumgalactic medium (CGM) as argued in Renzini (2020).…”

“…This paper aims to show that the j − M relation can be characterized in small and low-mass galaxies at redshifts from z = 0.4-1.4, opening up new parameter space thanks to the MUSE instrument and to our 3D modeling approach. Contrary to galaxies in the local universe where the j − M relation can be studied independently for the stellar j or gas components j gas (e.g., Obreschkow & Glazebrook 2014;Obreschkow et al 2016;Li et al 2020;Mancera Piña et al 2021), this is currently extremely challenging in distant galaxies at z 1.0 or beyond. One should note that the gas sAM j gas in this context is derived solely from H i data at z = 0, and it is often assumed that the sAM for the star-forming gas (molecular or ionized) is similar to j because of the similar extent (Leroy et al 2008;Nelson et al 2016;Wilman et al 2020) and kinematics (Martinsson et al 2013;Lang et al 2020) 1 .…”