The MOONS instrument possesses an exceptional combination of large multiplexing, high sensitivity, broad simultaneous spectral coverage (from optical to near-infrared bands), large patrol area and high fibre density. These properties provide the unpr
ecedented potential of enabling, for the very first time, SDSS-like surveys around Cosmic Noon (z~1-2.5), when the star formation rate in the Universe peaked. The high-quality spectra delivered by MOONS will sample the same nebular and stellar diagnostics observed in extensive surveys of local galaxies, providing an accurate and consistent description of the evolution of various physical properties of galaxies, and hence a solid test of different scenarios of galaxy formation and transformation. Most importantly, by spectroscopically identifying hundreds of thousands of galaxies at high redshift, the MOONS surveys will be capable of determining the environments in which primeval galaxies lived and will reveal how such environments affected galaxy evolution. In this article, we specifically focus on the main Guaranteed Time Observation (GTO) MOONS extragalactic survey, MOONRISE, by providing an overview of its scientific goals and observing strategy.
Galactic outflows are known to consist of several gas phases, however, so far the connection between these multiple phases has been investigated little and only in a few objects. In this paper, we analyse MUSE/VLT data of 26 local (U)LIRGs and study
their ionised and neutral atomic phases. We also include objects from the literature to obtain a total sample of 31 galaxies with spatially resolved multi-phase outflow information. We find that the ionized phase of the outflows has on average an electron density three times higher than the disc ($n_{rm e, disc}$ $sim$ 145 cm$^{-3}$ vs $n_{rm e, outflow}$ $sim$ 500 cm$^{-3}$), suggesting that cloud compression in the outflow is more important that cloud dissipation. We find that the difference in extinction between outflow and disc correlates with the outflow gas mass. Together with the analysis of the outflow velocities, this suggests that at least some of the outflows are associated with the ejection of dusty clouds from the disc. This may support models where radiation pressure on dust contributes to driving galactic outflows. The presence of dust in outflows is relevant for potential formation of molecules inside them. We combine our data with millimetre data to investigate the molecular phase. We find that the molecular phase accounts for more than 60 $%$ of the total mass outflow rate in most objects and this fraction is higher in AGN-dominated systems. The neutral atomic phase contributes of the order of 10 $%$, while the ionized phase is negligible. The ionized-to-molecular mass outflow rate declines slightly with AGN luminosity, although with a large scatter.
ALMA observations have revealed that [CII] 158$mu$m line emission in high-z galaxies is ~2-3$times$ more extended than the UV continuum emission. Here we explore whether surface brightness dimming (SBD) of the [CII] line is responsible for the report
ed [CII] deficit, and the large $L_{rm [OIII]}/L_{rm [CII]}$ luminosity ratio measured in early galaxies. We first analyse archival ALMA images of nine z>6 galaxies observed in both [CII] and [OIII]. After performing several uv-tapering experiments to optimize the identification of extended line emission, we detect [CII] emission in the whole sample, with an extent systematically larger than the [CII] emission. Next, we use interferometric simulations to study the effect of SBD on the line luminosity estimate. About 40% of the extended [CII] component might be missed at an angular resolution of 0.8$^{primeprime}$, implying that $L_{rm [CII]}$ is underestimated by a factor $approx2$ in data at low (<7) signal-to-noise ratio . By combining these results, we conclude that $L_{rm [CII]}$ of z>6 galaxies lies, on average, slightly below the local $L_{rm [CII]}-SFR$ relation ($Delta^{z=6-9}=-0.07pm0.3$), but within the intrinsic dispersion of the relation. SBD correction also yields $L_{rm [OIII]}/L_{rm [CII]}<10$, i.e. more in line with current hydrodynamical simulations.
We investigate the discrepancy between oxygen abundance estimations for narrow-line regions (NLRs) of Active Galactic Nuclei (AGNs) type Seyfert 2 derived by using direct estimations of the electron temperature (Te-method) and those derived by using
photoionization models. In view of this, observational emission-line ratios in the optical range (3000 < lambda(AA) < 7000) of Seyfert 2 nuclei compiled from the literature were reproduced by detailed photoionization models built with the Cloudy code. We find that the derived discrepancies are mainly due to the inappropriate use of the relations between temperatures of the low (t2) and high (t3) ionization gas zones derived for H II regions in AGN chemical abundance studies. Using a photoionization model grid, we derived a new expression for t2 as a function of t3 valid for Seyfert 2 nuclei. The use of this new expression in the AGN estimation of the O/H abundances based on Te-method produces O/H abundances slightly lower (about 0.2 dex) than those derived from detailed photoionization models. We also find that the new formalism for the Te-method reduces by about 0.4 dex the O/H discrepancies between the abundances obtained from strong emission-line calibrations and those derived from direct estimations.
We model gas phase metallicity radial profiles of galaxies in the local Universe by building on the `bathtub chemical evolution formalism - where a galaxys gas content is determined by the interplay between inflow, star formation and outflows. In par
ticular, we take into account inside-out disc growth and add physically-motivated prescriptions for radial gradients in star formation efficiency (SFE). We fit analytical models against the metallicity radial profiles of low-redshift star-forming galaxies in the mass range $log(M_star/M_odot)$ = [9.0-11.0] derived by Belfiore et al. 2017, using data from the MaNGA survey. The models provide excellent fits to the data and are capable of reproducing the change in shape of the radial metallicity profiles, including the flattening observed in the centres of massive galaxies. We derive the posterior probability distribution functions for the model parameters and find significant degeneracies between them. The parameters describing the disc assembly timescale are not strongly constrained from the metallicity profiles, while useful constrains are obtained for the SFE (and its radial dependence) and the outflow loading factor. The inferred value for the SFE is in good agreement with observational determinations. The inferred outflow loading factor is found to decrease with stellar mass, going from nearly unity at $log(M_star/M_odot) = 9.0$ to close to zero at $log(M_star/M_odot) =11.0$, in general agreement with previous empirical determinations. These values are the lowest we can obtain for a physically-motivated choice of initial mass function and metallicity calibration. We explore alternative choices which produce larger loading factors at all masses, up to order unity at the high-mass end.
We present new ALMA observations aimed at mapping molecular gas reservoirs through the CO(3-2) transition in three quasars at $zsimeq2.4$, LBQS 0109+0213, 2QZ J002830.4-281706, and [HB89] 0329-385. Previous [OIII]5007 observations of these quasars sh
owed evidence for ionised outflows quenching star formation in their host galaxies. Systemic CO(3-2) emission has been detected only in one quasar, LBQS 0109+0213, where the CO(3-2) emission is spatially anti-correlated with the ionised outflow, suggesting that most of the molecular gas may have been dispersed or heated in the region swept by the outflow. In all three sources, including the one detected in CO, our constraints on the molecular gas mass indicate a significantly reduced reservoir compared to main-sequence galaxies at the same redshift, supporting a negative feedback scenario. In the quasar 2QZ J002830.4-281706, we tentatively detect an emission line blob blue-shifted by $vsim-2000$ km/s with respect to the galaxy systemic velocity and spatially offset by 0.2 arcsec (1.7 kpc) with respect to the ALMA continuum peak. Interestingly, such emission feature is coincident in both velocity and space with the ionised outflow as seen in [OIII]5007. This tentative detection must be confirmed with deeper observations but, if real, it could represent the molecular counterpart of the ionised gas outflow driven by the AGN. Finally, in all ALMA maps we detect the presence of serendipitous line emitters within a projected distance $sim 160$ kpc from the quasars. By identifying these features with the CO(3-2) transition, the serendipitous line emitters would be located within |$Delta v$|$<$500 km/s from the quasars, hence suggesting an overdensity of galaxies in two out of three quasars.
Recent observations have revealed massive galactic molecular outflows that may have physical conditions (high gas densities) required to form stars. Indeed, several recent models predict that such massive galactic outflows may ignite star formation w
ithin the outflow itself. This star-formation mode, in which stars form with high radial velocities, could contribute to the morphological evolution of galaxies, to the evolution in size and velocity dispersion of the spheroidal component of galaxies, and would contribute to the population of high-velocity stars, which could even escape the galaxy. Such star formation could provide in-situ chemical enrichment of the circumgalactic and intergalactic medium (through supernova explosions of young stars on large orbits), and some models also predict that it may contribute substantially to the global star formation rate observed in distant galaxies. Although there exists observational evidence for star formation triggered by outflows or jets into their host galaxy, as a consequence of gas compression, evidence for star formation occurring within galactic outflows is still missing. Here we report new spectroscopic observations that unambiguously reveal star formation occurring in a galactic outflow at a redshift of 0.0448. The inferred star formation rate in the outflow is larger than 15 Msun/yr. Star formation may also be occurring in other galactic outflows, but may have been missed by previous observations owing to the lack of adequate diagnostics.
We use the most extensive integral field spectroscopic map of a local galaxy, NGC 628, combined with gas and stellar mass surface density maps, to study the distribution of metals in this galaxy out to 3 effective radii ($rm R_e$). At each galactocen
tric distance, we compute the metal budget and thus constrain the mass of metals lost. We find that in the disc about 50% of the metals have been lost throughout the lifetime of the galaxy. The fraction of metals lost is higher in the bulge ($sim$70%) and decreases towards the outer disc ($rm sim 3 R_e$). In contrast to studies based on the gas kinematics, which are only sensitive to ongoing outflow events, our metal budget analysis enables us to infer the average outflow rate during the galaxy lifetime. By using simple physically motivated models of chemical evolution we can fit the observed metal budget at most radii with an average outflow loading factor of order unity, thus clearly demonstrating the importance of outflows in the evolution of disc galaxies of this mass range ($rm log(M_star/M_odot) sim 10)$. The observed gas phase metallicity is higher than expected from the metal budget and suggests late-time accretion of enriched gas, likely raining onto the disc from the metal-enriched halo.
We report new deep ALMA observations aimed at investigating the [CII]158um line and continuum emission in three spectroscopically confirmed Lyman Break Galaxies at 6.8<z<7.1, i.e. well within the re-ionization epoch. With Star Formation Rates of SFR
~ 5-15 Msun/yr these systems are much more representative of the high-z galaxy population than other systems targeted in the past by millimeter observations. For the galaxy with the deepest observation we detect [CII] emission at redshift z=7.107, fully consistent with the Lyalpha redshift, but spatially offset by 0.7 (4 kpc) from the optical emission. At the location of the optical emission, tracing both the Lyalpha line and the far-UV continuum, no [CII] emission is detected in any of the three galaxies, with 3sigma upper limits significantly lower than the [CII] emission observed in lower reshift galaxies. These results suggest that molecular clouds in the central parts of primordial galaxies are rapidly disrupted by stellar feedback. As a result, [CII] emission mostly arises from more external accreting/satellite clumps of neutral gas. These findings are in agreement with recent models of galaxy formation. Thermal far-infrared continuum is not detected in any of the three galaxies. However, the upper limits on the infrared-to-UV emission ratio do not exceed those derived in metal- and dust-poor galaxies.
MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a SDSS-IV survey that will obtain spatially resolved spectroscopy from 3600 AA to 10300 AA for a representative sample of over 10000 nearby galaxies. In this paper we present the analysis
of nebular emission line properties in 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. Using spatially resolved diagnostic diagrams we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, which illustrates that galaxy characterisations based on single fibre spectra are necessarily incomplete. We observe extended LINER-like emission (up to $rm 1 R_{e}$) in three galaxies. We make use of the $rm EW(H alpha)$ to argue that the observed emission is consistent with ionisation from hot evolved stars. We derive stellar population indices and demonstrate a clear correlation between $rm D_n(4000)$ and $rm EW(H delta_A)$ and the position in the ionisation diagnostic diagram: resolved galactic regions which are ionised by a Seyfert/LINER-like radiation field are also devoid of recent star formation and host older and/or more metal rich stellar populations. We also detect extraplanar LINER-like emission in two highly inclined galaxies, and identify it with diffuse ionised gas. We investigate spatially resolved metallicities and find a positive correlation between metallicity and star formation rate (SFR) surface density. We study the relation between N/O vs O/H on resolved scales. We find that, at given N/O, regions within individual galaxies are spread towards lower metallicities, deviating from the sequence defined by galactic central regions as traced by Sloan $3$ fibre spectra. We suggest that the observed dispersion can be a tracer for gas flows in galaxies: infalls of pristine gas and/or the effect of a galactic fountain.
