The physical properties of galactic winds are of paramount importance for our understanding of galaxy formation. Fortunately, they can be constrained using background quasars passing near star-forming galaxies (SFGs). From the 14 quasar$-$galaxy pair
s in our VLT/SINFONI Mgii Program for Line Emitters (SIMPLE) sample, we reobserved the 10 brightest galaxies in H$_{alpha}$ with the VLT/SINFONI with 0.7 seeing and the corresponding quasar with the VLT/UVES spectrograph. Applying geometrical arguments to these ten pairs, we find that four are likely probing galactic outflows, three are likely probing extended gaseous disks, and the remaining three are not classifiable because they are viewed face-on. In this paper we present a detailed comparison between the line-of-sight kinematics and the host galaxy emission kinematics for the pairs suitable for wind studies. We find that the kinematic profile shapes (asymmetries) can be well reproduced by a purely geometrical wind model with a constant wind speed, except for one pair (towards J2357$-$2736) that has the smallest impact parameter b = 6 kpc and requires an accelerated wind flow. Globally, the outflow speeds are $sim$ 100 km/s and the mass ejection rates (or $dot M _{rm out}$) in the gas traced by the low-ionization species are similar to the star formation rate (SFR), meaning that the mass loading factor, $eta$ = $dot M _{rm out}$/SFR, is $sim$1.0. The outflow speeds are also smaller than the local escape velocity, which implies that the outflows do not escape the galaxy halo and are likely to fall back into the interstellar medium.
The circumgalactic medium (CGM) of typical galaxies is crucial to our understanding of the cycling of gas into, through and out of galaxies. One way to probe the CGM is to study gas around galaxies detected via the absorption lines they produce in th
e spectra of background quasars. Here, we present medium resolution and new ~0.4-arcsec resolution (~3 kpc at z~1) 3D observations with VLT/SINFONI of galaxies responsible for high-N(HI) quasar absorbers. These data allow to determine in details the kinematics of the objects: the four z~1 objects are found to be rotation-supported as expected from inclined discs, while the fifth z~2 system is dispersion-dominated. Two of the systems show sign of interactions and merging. In addition, we use several indicators (star formation per unit area, a comparison of emission and absorption kinematics, arguments based on the inclination and the orientation of the absorber to the quasar line-of-sight and the distribution of metals) to determine the direction of the gas flows in and out of these galaxies. In some cases, our observations are consistent with the gas seen in absorption being due to material co-rotating with their halos. In the case of absorbing-galaxies towards Q1009-0026 and Q2222-0946, these indicators point toward the presence of an outflow traced in absorption.
We report three additional SINFONI detections of H-alpha emission line from quasar absorbers, two of which are new identifications. These were targeted among a sample of systems with log N(HI)>19.0 and metallicities measured from high-resolution spec
troscopy. The detected galaxies are at impact parameters ranging from 6 to 12 kpc from the quasars line-of-sight. We derive star formation rates (SFR) of a few solar masses per year for the two absorbers at z_abs~1 and SFR=17 solar masses per year for the DLA at z_abs~2. These three detections are found among a sample of 16 DLAs and sub-DLAs (5 at z_abs~1 and 7 at z_abs~2). For the remaining undetected galaxies, we derive flux limits corresponding to SFR<0.1--11.0 solar masses per year depending on redshift of the absorber and depth of the data. When combined with previous results from our survey for galaxy counterparts to HI-selected absorbers, we find a higher probability of detecting systems with higher metallicity as traced by dust-free [Zn/H] metallicity. We also report a higher detection rate with SINFONI for host galaxies at z_abs~1 than for systems at z_abs~2. Using the NII/H-alpha ratio, we can thus compare absorption and emission metallicities in the same high-redshift objects, more than doubling the number of systems for which such measures are possible.
We analyze the physical conditions in the low-ionization component of starburst outflows (in contrast to the high-ionization wind fluid observed in X-rays), based on new Keck/LRIS spectroscopy of partially resolved absorption troughs in near-ultravio
let and optical spectra of Ultraluminous Infrared Galaxies. The large velocity width and blueshift present in seven, atomic transitions indicate a macroscopic velocity gradient within the outflowing gas. The mgII 2796, 2803 (and feII 2587, 2600) doublet lines in these data constrains the gas kinematics better than the heavily blended ad 5892, 98 doublet. The identical shape of the mgII 2796 absorption troughs to that of the normally weaker transition at 2803AA requires both transitions be optically thick at all outflow velocities. The fraction of the galactic continuum covered by the outflow at each velocity therefore dictates the shape of these absorption troughs. We suggest that the velocity offset of the deepest part of the troughs, where the covering factor of low-ionization gas is near unity, reflects the speed of a shell of swept-up, interstellar gas at the time of blowout. In a spherical outflow, we show that the fragments of this shell expand slowly relative to the geometrical dilution; and the covering fraction of low-ionization gas decreases with increasing radius. Our measurement of a covering factor that decreases with increasing velocity can therefore be interpreted as evidence that the low-ionization outflow is accelerating. We also present measurements of C_f(v) in 4 species, place an upper limit of 3000 cm3 on the density of the outflowing gas, and discuss lower limits on the mass outflow rate.
In these proceedings, we summarize recent results from our SINS VLT/SINFONI integral-field survey, focusing on the 52 detected UV/optically-selected star-forming galaxies at z~2. Our H-alpha emission-line imaging and kinematic data of these systems i
llustrates that a substantial fraction (> 1/3) of these galaxies are large, rotating disks and that these disks are clumpy, thick, and forming stars rapidly. We compare these systems to local disk scaling relations and find that the backbones of these relations are already in place at z~2. Detailed analysis of the large disks in our sample provides strong evidence that this population cannot result from a merger-dominated formation history and instead must be assembled by the smooth but rapid inflow of gas along filaments. These systems will then secularly evolve from clump-dominated disks to bulge-dominated disks on short timescales, a phenomenon that is observed in our SINS observations and is consistent with predictions from numerical simulations. These results provide new and exciting insights into the formation of bulge-dominated galaxies in the local Universe.
Low-ionization transitions such as the MgII 2796/2803 doublet trace cold gas in the vicinity of galaxies. It is not clear whether this gas is part of the interstellar medium of large proto-disks, part of dwarfs, or part of entrained material in super
novae-driven outflows. Studies based on MgII statistics, e.g. stacked images and clustering analysis, have invoked starburst-driven outflows where MgII absorbers are tracing the denser and colder gas of the outflow. A consequence of the outflow scenario is that the strongest absorbers ought to be associated with starbursts. We use the near-IR integral field spectrograph SINFONI to test whether starbursts are found around z~1 MgII absorbers. For 67% (14 out of 21) of the absorbers with rest-frame equivalent width larger than 2 AA, we do detect Ha in emission within 200 km/s of the predicted wavelength based on the MgII redshift. The star-formation rate (SFR) inferred from Halpha ranges from 1 to 20 Msun/yr, i.e. showing a level of star-formation larger than in M82 by a factor of >4 on average. Our flux limit (3-sigma) corresponds to a SFR of 0.5 Msun/yr. We find evidence (at >95% confidence) for a correlation between SFR and equivalent width, indicating a physical connection between starburst phenomena and gas seen in absorption. In the cases where we can extract the velocity field, the host-galaxies reside in halos with mean mass <log M_h>=11.2 in good agreement with clustering measurements.
