Galaxy formation and evolution

Abstract:

We present new ALMA observations of the CO(3-2) transition and 854micron continuum at 0.06-0.3" resolution, together with new VLT/SINFONI observations of NGC7172. This is a luminous (bolometric luminosity of ~10^44 erg/s) Seyfert galaxy that belongs to the Galaxy Activity, Torus, and Outflow Survey (GATOS). The CO(3-2) observations reveal the presence of a highly inclined cold molecular gas ring with an approximate radius of 3-4"~540-720 pc, which is likely associated with an inner Lindblad resonance of a putative stellar bar. There are noncircular motions in the VLT/SINFONI [SiVI]1.96micron and H2 at 2.12micron, and ALMA CO(3-2) velocity fields. After subtracting the stellar velocity field, we detected [SiVI] blueshifted velocities of a few hundred km/s to the south of the AGN. They trace outflowing ionized gas outside the plane of the galaxy and out to projected distances of ~200 pc. The CO(3-2) position-velocity diagram along the kinematic minor axis displays noncircular motions with observed velocities of up to ~150 km/s. Assuming that these are taking place in the disk of the galaxy, the observed velocity signs imply that the molecular gas ring is not only rotating but also outflowing. We derived an integrated cold molecular gas mass outflow rate of ~40 Msun/yr for the ring. Using the 854micron map, we resolved a 32 pc radius torus with a gas mass of 8x10^5 Msun. These torus properties are similar to other Seyfert galaxies in the GATOS sample. We measured a decreased cold molecular gas concentration in the nuclear-torus region relative to the circumnuclear region when compared to other less luminous Seyfert galaxies. We conclude that the effects of AGN feedback in NGC7172, which are likely caused by the AGN wind and/or the moderate luminosity radio jet, are seen as a large-scale outflowing molecular gas ring and accompanying redistribution of molecular gas in the nuclear regions.Comment: Accepted for publication to A&

Abstract:

We present new CO (J = 5-4 and 7-6) and [C I] (3P2-3P1 and 3P1-3P0) emission line observations of the star-forming galaxy D49 at the massive end of the main sequence at z = 3. We incorporate previous CO (J = 3-2) and optical-to-millimetre continuum observations to fit its spectral energy distribution. Our results hint at high-J CO luminosities exceeding the expected location on the empirical correlations with the infrared luminosity. [CI] emission fully consistent with the literature trends is found. We do not retrieve any signatures of a bright active galactic nucleus that could boost the J = 5-4, 7-6 lines in either the infrared or X-ray bands, but warm photon-dominated regions, shocks, or turbulence could in principle do so. We suggest that mechanical heating could be a favourable mechanism able to enhance the gas emission at fixed infrared luminosity in D49 and other main-sequence star-forming galaxies at high redshift, but further investigation is necessary to confirm this explanation. We derive molecular gas masses from dust, CO, and [C I] that all agree within the uncertainties. Given its high star formation rate ~500 Mo yr-1 and stellar mass > 1011.5 Mo, the short depletion timescale of < 0.3 Gyr might indicate that D49 is experiencing its last growth spurt and will soon transit to quiescence.

Abstract:

We have measured the angular autocorrelation function of near-infrared galaxies in SERVS + DeepDrill, the Spitzer Extragalactic Representative Volume Survey and its follow-up survey of the Deep Drilling Fields, in three large fields totalling over 20 deg² on the sky, observed in two bands centred on 3.6 and 4.5 μm. We performed this analysis on the full sample as well as on sources selected by [3.6]–[4.5] colour in order to probe clustering for different redshift regimes. We estimated the spatial correlation strength as well, using the redshift distribution from S-COSMOS with the same source selection. The strongest clustering was found for our bluest subsample, with 〈z〉 ∼ 0.7, which has the narrowest redshift distribution of all our subsamples. We compare these estimates to previous results from the literature, but also to estimates derived from mock samples, selected in the same way as the observational data, using deep light-cones generated from the SHARK semi-analytical model of galaxy formation. For all simulated (sub)samples, we find a slightly steeper slope than for the corresponding observed ones, but the spatial clustering length is comparable in most cases.