Angular momentum evolution of galaxies over the past 10 Gyr: A MUSE and KMOS dynamical survey of 400 star-forming galaxies from $z$ = 0.3–1.7

Abstract

(2017) 'Angular momentum evolution of galaxies over the past 10 Gyr : a MUSE and KMOS dynamical survey of 400 star-forming galaxies from z = 0.3 to 1.7.', Monthly notices of the Royal Astronomical Society., 467 (3). pp. 3140-3159.Further information on publisher's website: Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTWe present a MUSE and KMOS dynamical study 405 star-forming galaxies at redshift z = 0.28-1.65 (median redshiftz = 0.84). Our sample is representative of the star-forming "main-sequence", with star-formation rates of SFR = 0.1-30 M ⊙ yr −1 and stellar masses M ⋆ = 10 8 -10 11 M ⊙ . For 49 ± 4% of our sample, the dynamics suggest rotational support, 24 ± 3% are unresolved systems and 5 ± 2% appear to be early-stage major mergers with components on 8-30 kpc scales. The remaining 22 ± 5% appear to be dynamically complex, irregular (or face-on systems). For galaxies whose dynamics suggest rotational support, we derive inclination corrected rotational velocities and show these systems lie on a similar scaling between stellar mass and specific angular momentum as local spirals with⋆ but with a redshift evolution that scales as j ⋆ ∝ M 2/3 ⋆ (1 + z) −1 . We also identify a correlation between specific angular momentum and disk stability such that galaxies with the highest specific angular momentum (log(j ⋆ / M 2/3 ⋆ ) > 2.5) are the most stable, with Toomre Q = 1.10 ± 0.18, compared to Q = 0.53 ± 0.22 for galaxies with log(j ⋆ / M 2/3 ⋆ ) < 2.5. At a fixed mass, the HST morphologies of galaxies with the highest specific angular momentum resemble spiral galaxies, whilst those with low specific angular momentum are morphologically complex and dominated by several bright star-forming regions. This suggests that angular momentum plays a major role in defining the stability of gas disks: at z ∼ 1, massive galaxies that have disks with low specific angular momentum, are globally unstable, clumpy and turbulent systems. In contrast, galaxies with high specific angular have evolved in to stable disks with spiral structure where star formation is a local (rather than global) process.

The SAMI Galaxy Survey: satellite galaxies undergo little structural change during their quenching phase

“…From theoretical models of structure formation (e.g., White 1984;Mo et al 1998), hydrodynamical simulations (e.g., Pedrosa & Tissera 2015;Lagos et al 2017), as well as recent observations (e.g., Simons et al 2017;Swinbank et al 2017), we see that star-forming central disk galaxies gradually increase their spin with time (solid green line in the top panel), due to the continuing accretion of gas which, on average, is expected to bring high specific angular momentum (e.g., Catelan & Theuns 1996;El-Badry et al 2018). The typical increase expected in the stellar spin parameter from z∼1 to 0 is ∼0.3 dex in our stellar mass range (Lagos et al 2017), consistent with the observed decrease in gas velocity dispersion (Wisnioski et al 2015;Simons et al 2017) and increase in gas specific angular momentum (Swinbank et al 2017). After infall, the spin of satellite galaxies either remains constant or slightly decreases (solid red line) whereas centrals keep acquiring angular momentum (dashed green line).…”

Abundance and group coalescence time-scales of compact groups of galaxies in the EAGLE simulation

“…EAGLE is calibrated to match the galaxy stellar mass function and galaxy sizes at z = 0.1, but has been shown to reproduce a large number of observables over a large range of redshifts, such as the evolution of stellar mass (Furlong et al 2015), galaxy sizes (Furlong et al 2017) and the evolution of galaxy angular momentum (Swinbank et al 2017).…”

Angular momentum of z ∼ 1.5 galaxies and their local analogues with adaptive optics

“…The z ∼ 1.5 masses are derived from SED fitting with hyper-z (Bolzonella et al 2000), using the methods described in Swinbank et al (2017). We adopt measurement uncertainties of a standard 0.2 dex to conservatively account for deviations in results between common SED fitting codes, and possible effects of low photometric signal-to-noise (Mobasher et al 2015).…”

“…We suggest that some fraction of the scatter in M * − j * presented by other studies at high redshift may thus be driven by including a greater number of mergers as if they were rotating disks; this could be checked by measuring j * in the manner described in the current paper for the SINS/zC-SINF AO and non-AO datasets. Most other high-z studies (Förster Schreiber et al 2006;Burkert et al 2016;Contini et al 2016;Swinbank et al 2017;Harrison et al 2017) find that j * ∝ M 2/3 for the 2D relation (with the exception of Alcorn et al (2018) who found a shallower slope, but note that they compute j * from integrated spectra). However, the normalisation of this relation leads to a wide range of conclusions about the redshift evolution (1 + z) n , ranging from n = 0 (Burkert et al 2016;Alcorn et al 2018) to n = −1.5 (Förster Schreiber et al 2006).…”

“…Lagos et al 2017;Teklu et al 2015), linked to lower disk stability against formation of their star-forming clumps (Obreschkow et al 2015). There are few analyses at high redshift, owing to the scarcity of high-resolution observations of such galaxies, and all use the proxy j = krv for some characteristic radius r and velocity v, with proportionality k dependent on the Sérsic index (Sérsic 1963) in an effort to account for the variation in j * with morphology (Förster Schreiber et al 2006;Burkert et al 2016;Contini et al 2016;Swinbank et al 2017;Harrison et al 2017;Alcorn et al 2018). Most find α consistent with 2/3, with redshift dependence varying from no evolution (Burkert et al 2016;Alcorn et al 2018) up to a factor of (1+z) −1.5 (Förster Schreiber et al 2006).…”