Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMUSE Analysis of Gas around Galaxies (MAGG) -- III: The gas and galaxy environment of z = 3-4.5 quasars
127
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We present a study of the environment of 27 z=3-4.5 bright quasars from the MUSE Analysis of Gas around Galaxies (MAGG) survey. With medium-depth MUSE observations (4 hours on target per field), we characterise the effects of quasars on their surroundings by studying simultaneously the properties of extended gas nebulae and Lyalpha emitters (LAEs) in the quasar host haloes. We detect extended (up to ~ 100 kpc) Lyalpha emission around all MAGG quasars, finding a very weak redshift evolution between z=3 and z=6. By stacking the MUSE datacubes, we confidently detect extended emission of CIV and only marginally detect extended HeII up to ~40 kpc, implying that the gas is metal enriched. Moreover, our observations show a significant overdensity of LAEs within 300 km/s from the quasar systemic redshifts estimated from the nebular emission. The luminosity functions and equivalent width distributions of these LAEs show similar shapes with respect to LAEs away from quasars suggesting that the Lyalpha emission of the majority of these sources is not significantly boosted by the quasar radiation or other processes related to the quasar environment. Within this framework, the observed LAE overdensities and our kinematic measurements imply that bright quasars at z=3-4.5 are hosted by haloes in the mass range ~ 10^{12.0}-10^{12.5} Msun.
rate research
Read More
We present a study of the metal-enriched cool halo gas traced by MgII absorption around 228 galaxies at z~0.8-1.5 within 28 quasar fields from the MUSE Analysis of Gas around Galaxies (MAGG) survey. We observe no significant evolution in the MgII equivalent width versus impact parameter relation and in the MgII covering fraction compared to surveys at z<~0.5. The stellar mass, along with distance from galaxy centre, appears to be the dominant factor influencing the MgII absorption around galaxies. With a sample that is 90% complete down to a star formation rate of ~0.1 Msun/yr and up to impact parameters ~250-350 kpc from quasars, we find that the majority (67^{+12}_{-15}% or 14/21) of the MgII absorption systems are associated with more than one galaxy. The complex distribution of metals in these richer environments adds substantial scatter to previously-reported correlations. Multiple galaxy associations show on average five times stronger absorption and three times higher covering fraction within twice the virial radius than isolated galaxies. The dependence of MgII absorption on galaxy properties disfavours the scenario in which a widespread intra-group medium dominates the observed absorption. This leaves instead gravitational interactions among group members or hydrodynamic interactions of the galaxy haloes with the intra-group medium as favoured mechanisms to explain the observed enhancement in the MgII absorption strength and cross section in rich environments.
We present the design, methods, and first results of the MUSE Analysis of Gas around Galaxies (MAGG) survey, a large programme on the Multi Unit Spectroscopic Explorer (MUSE) instrument at the Very Large Telescope (VLT) which targets 28 z > 3.2 quasars to investigate the connection between optically-thick gas and galaxies at z~3-4. MAGG maps the environment of 52 strong absorption line systems at z > 3, providing the first statistical sample of galaxies associated with gas-rich structures in the early Universe. In this paper, we study the galaxy population around a very metal poor gas cloud at z~3.5 towards the quasar J124957.23-015928.8. We detect three Lyman alpha emitters within <200km/s of the cloud redshift, at projected separations <185 kpc (physical). The presence of star-forming galaxies near a very metal-poor cloud indicates that metal enrichment is still spatially inhomogeneous at this redshift. Based on its very low metallicity and the presence of nearby galaxies, we propose that the most likely scenario for this LLS is that it lies within a filament which may be accreting onto a nearby galaxy. Taken together with the small number of other LLSs studied with MUSE, the observations to date show a range of different environments near strong absorption systems. The full MAGG survey will significantly expand this sample and enable a statistical analysis of the link between gas and galaxies to pin down the origin of these diverse environments at z~3-4.
We use the MusE GAs FLOw and Wind (MEGAFLOW) survey to study the kinematics of extended disk-like structures of cold gas around $zapprox1$ star-forming galaxies. The combination of VLT/MUSE and VLT/UVES observations allows us to connect the kinematics of the gas measured through MgII quasar absorption spectroscopy to the kinematics and orientation of the associated galaxies constrained through integral field spectroscopy. Confirming previous results, we find that the galaxy-absorber pairs of the MEGAFLOW survey follow a strong bimodal distribution, consistent with a picture of MgII absorption being predominantly present in outflow cones and extended disk-like structures. This allows us to select a bona-fide sample of galaxy-absorber pairs probing these disks for impact parameters of 10-70 kpc. We test the hypothesis that the disk-like gas is co-rotating with the galaxy disks, and find that for 7 out of 9 pairs the absorption velocity shares the sign of the disk velocity, disfavouring random orbits. We further show that the data are roughly consistent with inflow velocities and angular momenta predicted by simulations, and that the corresponding mass accretion rates are sufficient to balance the star formation rates.
In this paper we present Multi Unit Spectroscopic Explorer (MUSE) integral field unit spectroscopic observations of the $sim70times30$ kpc$^2$ Ly$alpha$ halo around the radio galaxy 4C04.11 at $z = 4.5077$. High-redshift radio galaxies (HzRGs) are hosted by some of the most massive galaxies known at any redshift and are unique markers of concomitant powerful active galactic nucleus (AGN) activity and star formation episodes. We map the emission and kinematics of the Ly$alpha$ across the halo as well as the kinematics and column densities of eight HI absorbing systems at $-3500 < Delta v < 0$ km s$^{-1}$. We find that the strong absorber at $Delta v sim 0,rm km,s^{-1}$ has a high areal coverage ($30times30$ kpc$^2$), being detected across a large extent of the Ly$alpha$ halo, a significant column density gradient along the southwest to northeast direction, and a velocity gradient along the radio jet axis. We propose that the absorbing structure, which is also seen in CIV and NV absorption, represents an outflowing metal-enriched shell driven by a previous AGN or star formation episode within the galaxy and is now caught up by the radio jet, leading to jet-gas interactions. These observations provide evidence that feedback from AGN in some of the most massive galaxies in the early Universe may play an important role in redistributing material and metals in their environments.
We present results from our on-going MusE GAs FLOw and Wind (MEGAFLOW) survey, which consists of 22 quasar lines-of-sight, each observed with the integral field unit (IFU) MUSE and the UVES spectrograph at the ESO Very Large Telescopes (VLT). The goals of this survey are to study the properties of the circum-galactic medium around $zsim1$ star-forming galaxies. The absorption-line selected survey consists of 79 strong MgII absorbers (with rest-frame equivalent width (REW)$gtrsim$0.3AA) and, currently, 86 associated galaxies within 100 projected~kpc of the quasar with stellar masses ($M_star$) from $10^9$ to $10^{11}$ msun. We find that the cool halo gas traced by MgII is not isotropically distributed around these galaxies, as we show the strong bi-modal distribution in the azimuthal angle of the apparent location of the quasar with respect to the galaxy major-axis. This supports a scenario in which outflows are bi-conical in nature and co-exist with a coplanar gaseous structure extending at least up to 60 to 80 kpc. Assuming that absorbers near the minor axis probe outflows, the current MEGAFLOW sample allowed us to select 26 galaxy-quasar pairs suitable for studying winds. From this sample, using a simple geometrical model, we find that the outflow velocity only exceeds the escape velocity when $M_{star}lesssim 4times10^9$~msun, implying the cool material is likely to fall back except in the smallest halos. Finally, we find that the mass loading factor $eta$, the ratio between the ejected mass rate and the star formation rate (SFR), appears to be roughly constant with respect to the galaxy mass.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
