Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userMUSE Analysis of Gas around Galaxies (MAGG) -- II: Metal-enriched halo gas around z~1 galaxies
100
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
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.
rate research
Read More
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.
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 present the first results from a Hubble Space Telescope WFC3/IR program, which obtained direct imaging and grism observations of galaxies near quasar sightlines with a high frequency of uncorrelated foreground Mg II absorption. These highly efficient observations targeted 54 Mg II absorbers along the line of sight to nine quasars at $z_{qso}sim2$. We find that 89% of the absorbers in the range $0.64< z < 1.6$ can be spectroscopically matched to at least one galaxy with an impact parameter less than 200 kpc and $|Delta z|/(1+z)<0.006$. We have estimated the star formation rates and measured structural parameters for all detected galaxies with impact parameters in the range 7-200 kpc and star formation rates greater than 1.3 M$_{odot}$ yr$^{-1}$. We find that galaxies associated with Mg II absorption have significantly higher mean star formation rates and marginally higher mean star formation rate surface densities compared to galaxies with no detected Mg II. Nearly half of the Mg II absorbers match to more than one galaxy, and the mean equivalent width of the Mg II absorption is found to be greater for groups, compared to isolated galaxies. Additionally, we observe a significant redshift evolution in the physical extent of Mg II-absorbing gas around galaxies and evidence of an enhancement of Mg II within 50 degrees of the minor axis, characteristic of outflows, which persists to 80 kpc around the galaxies, in agreement with recent predictions from simulations.
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.
Absorption-line spectroscopy of multiply-lensed QSOs near a known foreground galaxy provides a unique opportunity to go beyond the traditional one-dimensional application of QSO probes and establish a crude three-dimensional (3D) map of halo gas around the galaxy that records the line-of-sight velocity field at different locations in the gaseous halo. Two intermediate-redshift galaxies are targeted in the field around the quadruply-lensed QSO HE0435-1223 at redshift z=1.689, and absorption spectroscopy along each of the lensed QSOs is carried out in the vicinities of these galaxies. One galaxy is a typical, star-forming L* galaxy at z=0.4188 and projected distance of rho=50 kpc from the lensing galaxy. The other is a super-L* barred spiral at z=0.7818 and rho=33 kpc. Combining known orientations of the quadruply-lensed QSO to the two foreground galaxies with the observed MgII absorption profiles along individual QSO sightlines has for the first time led to spatially resolved kinematics of tenuous halo gas on scales of 5-10 kpc at z>0.2. A MgII absorber is detected in every sightline observed through the halos of the two galaxies, and the recorded absorber strength is typical of what is seen in previous close QSO--galaxy pair studies. While the multi-sightline study confirms the unity covering fraction of MgII absorbing gas at rho < 50 kpc from star-forming disks, the galaxies also present two contrasting examples of complex halo gas kinematics. Different models, including a rotating disk, collimated outflows, and gaseous streams from either accretion or tidal/ram-pressure stripping, are considered for comparisons with the absorption-line observations, and infalling streams/stripped gas of width >~ 10 kpc are found to best describe the observed gas kinematics across multiple sightlines.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
