The Square Kilometre Array (SKA)

Abstract:

The XXL survey currently covers two 25 deg2 patches with XMM observations of ~ 10ks. We summarise the scientific results associated with the first release of the XXL data set, that occurred mid 2016. We review several arguments for increasing the survey depth to 40 ks during the next decade of XMM operations. X-ray (z < 2) cluster, (z < 4) AGN and cosmic background survey science will then benefit from an extraordinary data reservoir. This, combined with deep multi-λ observations, will lead to solid standalone cosmological constraints and provide a wealth of information on the formation and evolution of AGN, clusters and the X-ray background. In particular, it will offer a unique opportunity to pinpoint the z > 1 cluster density. It will eventually constitute a reference study and an ideal calibration field for the upcoming eROSITA and Euclid missions.

Abstract:

We present dynamical measurements for 586 Hα-detected star-forming galaxies from the KMOS (K-band Multi-Object Spectrograph) Redshift One Spectroscopic Survey (KROSS). The sample represents typical star-forming galaxies at this redshift (z = 0.6-1.0), with a median star formation rate of ≈7 M ⊙ yr -1 and a stellar mass range of log (M * [M ⊙ ]) ≈ 9-11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully- Fisher relationship) for our rotationally dominated sources (v C /σ 0 > 1) has a consistent slope and normalization as that observed for z = 0 discs. In contrast, the specific angular momentum (j * angular momentum divided by stellar mass) is ≈0.2-0.3 dex lower on average compared to z = 0 discs. The specific angular momentum scales as j s ∝ M * 0.6±0.2 , consistent with that expected for dark matter (i.e. j DM ∝ M DM 2/3 ). We find that z≈ 0.9 star-forming galaxies have decreasing specific angular momentum with increasing Sérsic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disc-dominated morphologies. This implies that an angular momentum-mass-morphology relationship, similar to that observed in local massive galaxies, is already in place by z ≈ 1.