In this letter we study the mean sizes of Halpha clumps in turbulent diskgalaxies relative to kinematics, gas fractions, and Toomre Q. We use 100~pcresolution HST images, IFU kinematics, and gas fractions of a sample of rare,nearby turbulent disks with properties closely matched to z~1.5-2 main-sequencegalaxies (the DYNAMO sample). We find linear correlations of normalized meanclump sizes with both the gas fraction and the velocity dispersion-to-rotationvelocity ratio of the host galaxy. We show that these correlations areconsistent with predictions derived from a model of instabilities in aself-gravitating disk (the so-called "violent disk instability model"). We alsoobserve, using a two-fluid model for Q, a correlation between the size ofclumps and self-gravity driven unstable regions. These results are mostconsistent with the hypothesis that massive star forming clumps in turbulentdisks are the result of instabilities in self-gravitating gas-rich disks, andtherefore provide a direct connection between resolved clump sizes and this insitu mechanism.

Large scale filaments, with lengths that can reach tens of Mpc, are the mostprominent features in the cosmic web. These filaments have only been observedindirectly through the positions of galaxies in large galaxy surveys or throughabsorption features in the spectra of high redshift sources. In this study wepropose to go one step further and directly detect intergalactic mediumfilaments through their emission in the HI 21cm line. We make use of highresolution cosmological simulations to estimate the intensity of this emissionin low redshift filaments and use it to make predictions for the directdetectability of specific filaments previously inferred from galaxy surveys, inparticular the Sloan Digital Sky Survey. Given the expected signal of thesefilaments our study shows that HI emission from large filaments can be observedby current and next generation radio telescopes. We estimate that gas infilaments of length $l \gtrsim$ 15 $h^{-1}$Mpc with relatively smallinclinations to the line of sight ($\lesssim 10^\circ$) can be observed in$\sim40-100$ hours with telescopes such as GMRT or EVLA, potentially providinglarge improvements over our knowledge of the astrophysical properties of thesefilaments. Due to their large field of view and sufficiently long integrationtimes, upcoming HI surveys with the Apertif and ASKAP instruments will be ableto detect large filaments independently of their orientation and curvature.Furthermore, our estimates indicate that a more powerful future radio telescopelike SKA-2 can be used to map most of these filaments, which will allow them tobe used as a strong cosmological probe.

Supermassive black holes are the central engines of luminous quasars and arefound in most massive galaxies today. But the recent discoveries of ULASJ1120+0641, a 2 $\times$ 10$^9$ M$_{\odot}$ black hole at $z \sim$ 7.1, andSDSS J0100+2802, a 1.2 $\times$ 10$^{10}$ M$_{\odot}$ black hole at $z =$ 6.3,challenge current paradigms of cosmic structure formation because it is notknown how quasars this massive appeared less than a billion years after the BigBang. Here, we report new cosmological simulations of SMBHs with x-rays fullycoupled to primordial chemistry and hydrodynamics that show that J1120+0641 andJ0100+2802 can form from direct collapse black holes if their growth is fed bycold, dense accretion streams, like those thought to fuel the rapid growth ofsome galaxies at later epochs. Our models reproduce the mass, luminosity andionized near zone of J1120+0641, as well as the star formation rate andmetallicity in its host galaxy. They also match new observations of thedynamical mass of the central 1.5 kpc of its emission region just obtained withALMA. We find that supernova feedback from star formation in the host galaxyregulates the growth of the quasar from early times.

Galaxies in clusters are strongly affected by their environment. They evolveaccording to several physical mechanisms that are active in clusters. Theirefficiency can strongly depend on the orbital configuration of the galaxies.Our aim is to analyse the orbits of the galaxies in the cluster Abell 85, basedon the study of the galaxy velocity anisotropy parameter. We have solved theJeans equation under the assumption that the galaxies in A85 are collisionlessobjects, within the spherically symmetric gravitational potential of thevirialized cluster. The mass of the cluster was estimated with X-ray andcaustic analyses. We find that the anisotropy profile of the full galaxypopulation in A85 is an increasing monotonic function of the distance from thecluster centre: on average, galaxies in the central region (r/r200 < 0.3) areon isotropic orbits, while galaxies in the outer regions are on radial orbits.We also find that the orbital properties of the galaxies strongly depend ontheir stellar colour. In particular, blue galaxies are on less radial orbitsthan red galaxies. The different families of cluster galaxies considered herehave the pseudo phase-space density profiles Q(r) and Qr(r) consistent with theprofiles expected in virialized dark matter halos in $N$-body simulations. Thisresult suggests that the galaxies in A85 have reached dynamical equilibriumwithin the cluster potential. Our results indicate that the origin of the blueand red colour of the different galaxy populations is the different orbitalshape rather than the accretion time.

The spatial distribution of elemental abundances in the disc of our Galaxygives insights both on its assembly process and subsequent evolution, and onthe stellar nucleogenesis of the different elements. Gradients can be tracedusing several types of objects as, for instance, (young and old) stars, openclusters, HII regions, planetary nebulae. We aim at tracing the radialdistributions of abundances of elements produced through differentnucleosynthetic channels -the alpha-elements O, Mg, Si, Ca and Ti, and theiron-peak elements Fe, Cr, Ni and Sc - by using the Gaia-ESO idr4 results ofopen clusters and young field stars. From the UVES spectra of member stars, wedetermine the average composition of clusters with ages >0.1 Gyr. We derivestatistical ages and distances of field stars. We trace the abundance gradientsusing the cluster and field populations and we compare them with achemo-dynamical Galactic evolutionary model. Results. The adoptedchemo-dynamical model, with the new generation of metallicity-dependent stellaryields for massive stars, is able to reproduce the observed spatialdistributions of abundance ratios, in particular the abundance ratios of [O/Fe]and [Mg/Fe] in the inner disc (5 kpc<RGC <7 kpc), with their differences, thatwere usually poorly explained by chemical evolution models. Often, oxygen andmagnesium are considered as equivalent in tracing alpha-element abundances andin deducing, e.g., the formation time-scales of different Galactic stellarpopulations. In addition, often [alpha/Fe] is computed combining severalalpha-elements. Our results indicate, as expected, a complex and diversenucleosynthesis of the various alpha-elements, in particular in the highmetallicity regimes, pointing towards a different origin of these elements andhighlighting the risk of considering them as a single class with commonfeatures.