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International audience; There is cumulative evidence showing that, for the most massive galaxies, the fraction of disc-like objects compared to those with spheroidal properties increases with redshift. However, this evolution is thus far based on the surface brightness study of these objects. To explore the consistency of this scenario, it is necessary to measure the dynamical status of these galaxies. With this aim, we have obtained seeing-limited near-infrared integral-field spectra in the H-band for 10 massive galaxies (M-* \textgreater=10(11) h(70)(-2)M(circle dot)) at z similar to 1.4 with SINFONI at the VLT. Our sample is selected by their stellar mass and EW[O ii] \textgreater 15 A, to secure their kinematic measurements, but without accounting for any morphological or flux criteria a priori. Through this 3D kinematic spectroscopy analysis, we find that half (i.e. 50 +/- 7 per cent) of our galaxies are compatible with being rotationally supported discs, in agreement with previous morphological expectations. This is a factor of approximately 2 higher than what is observed in the present Universe for objects of the same stellar mass. Strikingly, the majority of our sample of massive galaxies show extended and fairly high rotational velocity maps, implying that massive galaxies acquire rapidly rotational support and hence gravitational equilibrium. Our sample also show evidence for ongoing interactions and mergers. Summarizing, massive galaxies at high-z show a significant diversity and must have continued evolution beyond the fading of stellar populations, to become their present-day counterparts.

We combine Hubble Space Telescope (HST) G102 and G141 near-IR (NIR) grism spectroscopy with HST/WFC3-UVIS, HST/WFC3-IR, and Spitzer/IRAC [3.6 μm] photometry to assemble a sample of massive (log (M star/M ⊙) ∼ 11.0) and quenched (specific star formation rate 2 and the z ∼ 1.5 RS. According to their estimated ages, the time required for quenched galaxies off the RS to join their counterparts on the z ∼ 1.5 RS is of the order of ∼1 Gyr. © 2013. The American Astronomical Society. All rights reserved.

We present the first robust measurement of the high redshift mass-metallicity (MZ) relation at 108 ≲ M/M ⊙ ≲ 1010, obtained by stacking spectra of 83 emission-line galaxies with secure redshifts between 1.3 ≲ z ≲ 2.3. For these redshifts, infrared grism spectroscopy with the Hubble Space Telescope Wide Field Camera 3 is sensitive to the R 23 metallicity diagnostic: ([O II] λλ3726, 3729 + [O III] λλ4959, 5007)/Hβ. Using spectra stacked in four mass quartiles, we find a MZ relation that declines significantly with decreasing mass, extending from 12+log(O/H) = 8.8 at M = 109.8 M ⊙, to 12+log(O/H) = 8.2 at M = 10 8.2 M ⊙. After correcting for systematic offsets between metallicity indicators, we compare our MZ relation to measurements from the stacked spectra of galaxies with M ≳ 109.5 M ⊙ and z ∼ 2.3. Within the statistical uncertainties, our MZ relation agrees with the z ∼ 2.3 result, particularly since our somewhat higher metallicities (by around 0.1 dex) are qualitatively consistent with the lower mean redshift (z = 1.76) of our sample. For the masses probed by our data, the MZ relation shows a steep slope which is suggestive of feedback from energy-driven winds, and a cosmological downsizing evolution where high mass galaxies reach the local MZ relation at earlier times. In addition, we show that our sample falls on an extrapolation of the star-forming main sequence (the SFR-M * relation) at this redshift. This result indicates that grism emission-line selected samples do not have preferentially high star formation rates (SFRs). Finally, we report no evidence for evolution of the mass-metallicity-SFR plane; our stack-averaged measurements show excellent agreement with the local relation. © 2013. The American Astronomical Society. All rights reserved.

Lenticular galaxies have long been thought of as evolved spirals, but the processes involved to quench the star formation are still unclear. By studying the individual star formation histories of the bulges and disks of lenticulars, it is possible to look for clues to the processes that triggered their transformation from spirals. To accomplish this feat, we present a new method for spectroscopic bulge-disk decomposition, in which a long-slit spectrum is decomposed into two one-dimensional spectra representing purely the bulge and disk light. We present preliminary results from applying this method to lenticular galaxies in the Virgo and Fornax Clusters, in which we show that the most recent star formation activity in these galaxies occurred within the bulges. We also find that the bulges are in general more Fe-enriched than the disks of the same galaxy, and that this enrichment grows stronger as the age of the bulge becomes younger. These results point towards a scenario where the star formation in the disks of spiral galaxies are quenched, followed by a burst of star formation in the central regions from the gas that has been funnelled inwards through the disk., Comment: 4 pages, 2 figures, To appear in the conference proceedings of The Structure and Dynamics of Disk Galaxies, M.S. Seigar and P. Treuthardt, eds

We present an atlas of a sample of local (z < 0.1) LIRGs (10) and ULIRGs (7) covering the luminosity range log(LIR/L⊙) = 11.1−12.4. The atlas is based on near-infrared H (1.45−1.85 μm) and K-band (1.95−2.45 μm) VLT-SINFONI integral field spectroscopy (IFS). The atlas presents the ionised, partially ionised, and warm molecular gas two-dimensional flux distributions and kinematics over an FoV of ~3 × 3 kpc (LIRGs) and ~12 × 12 kpc (ULIRGs) and with average linear resolutions of ~0.2 kpc and ~0.9 kpc, respectively. The different phases of the gas show a wide morphological variety with the nucleus as the brightest Brγ source for ~33% of the LIRGs and ~71% of the ULIRGs, whereas all the LIRGs and ULIRGs have their maximum H2 emission in their nuclear regions. In LIRGs, the ionised gas distribution is dominated by the emission from the star-forming rings or giant HII regions in the spiral arms. The Brγ and [FeII] line at 1.644 μm trace the same structures, although the emission peaks at different locations in some of the objects, and the [FeII] seems to be more extended and diffuse. The ULIRG subsample is at larger distances and contains mainly pre-coalescence interacting systems. Although the peaks of the molecular gas emission and the continuum coincide in ~71% of the ULIRGs, regions with intense Paα (Brγ) emission tracing luminous star-forming regions located at distances of 2−4 kpc away from the nucleus are also detected, usually associated with secondary nuclei or tidal tails. LIRGs have mean observed (i.e. uncorrected for internal extinction) SFR surface densities of about 0.4 to 0.9 M⊙ yr-1 kpc-2 over large areas (4−9 kpc2) with peaks of about 2−2.5 M⊙ yr-1 kpc-2 in the smaller regions (0.16 kpc2) associated with the nucleus of the galaxy or the brightest Brγ region. ULIRGs do have similar average SFR surface densities for the integrated emitting regions of ~0.4 M⊙ yr-1 kpc-2 in somewhat larger areas (100−200 kpc2) and for the Paα peak (~2 M⊙ yr-1 kpc-2 in 4 kpc2). The observed gas kinematics in LIRGs is primarily due to rotational motions around the centre of the galaxy, although local deviations associated with radial flows and/or regions of higher velocity dispersions are present. The ionised and molecular gas share the same kinematics (velocity field and velocity dispersion) to first order, showing slight differences in the velocity amplitudes (peak-to-peak) in some cases, whereas the average velocity dispersions are compatible within uncertainties. As expected, the kinematics of the ULIRG subsample is more complex, owing to the interacting nature of the objects of the sample.

Spectroscopic observations of Halpha and Hbeta emission lines of 128 star-forming galaxies in the redshift range 0.75, Comment: 11 pages, 9 figures, 2 tables; version addressing the referee comments

A new method for spectroscopic bulge-disc decomposition is presented, in which the spatial light profile in a two-dimensional spectrum is decomposed wavelength-by-wavelength into bulge and disc components, allowing separate one-dimensional spectra for each component to be constructed. This method has been applied to observations of a sample of nine S0s in the Fornax Cluster in order to obtain clean high-quality spectra of their individual bulge and disc components. So far this decomposition has only been fully successful when applied to galaxies with clean light profiles, consequently limiting the number of galaxies that could be separated into bulge and disc components. Lick index stellar population analysis of the component spectra reveals that in those galaxies where the bulge and disc could be distinguished, the bulges have systematically higher metallicities and younger stellar populations than the discs. This correlation is consistent with a picture in which S0 formation comprises the shutting down of star formation in the disc accompanied by a final burst of star formation in the bulge. The variation in spatial-fit parameters with wavelength also allows us to measure approximate colour gradients in the individual components. Such gradients were detected separately in both bulges and discs, in the sense that redder light is systematically more centrally concentrated in all components. However, a search for radial variations in the absorption line strengths determined for the individual components revealed that they are absent from the vast majority of S0 discs and bulges. The absence of gradients in line indices for most galaxies implies that the colour gradient cannot be attributed to age or metallicity variations, and is therefore most likely associated with varying degrees of obscuration by dust., 10 pages, 10 figures, 1 table, accepted for publication in MNRAS

Spatially resolved near-IR and X-ray imaging of the central region of the Luminous Infrared Galaxy NGC 5135 is presented. The kinematical signatures of strong outflows are detected in the [FeII]1.64 ��m emission line in a compact region at 0.9 kpc from the nucleus. The derived mechanical energy release is consistent with a supernova rate of 0.05-0.1 yr$^{-1}$. The apex of the outflowing gas spatially coincides with the strongest [FeII] emission peak and with the dominant component of the extranuclear hard X-ray emission. All these features provide evidence for a plausible direct physical link between supernova-driven outflows and the hard X-ray emitting gas in a LIRG. This result is consistent with model predictions of starbursts concentrated in small volumes and with high thermalization efficiencies. A single high-mass X-ray binary (HMXB) as the major source of the hard X-ray emission although not favoured, cannot be ruled out. Outside the AGN, the hard X-ray emission in NGC 5135 appears to be dominated by the hot ISM produced by supernova explosions in a compact star-forming region, and not by the emission due to HMXB. If this scenario is common to U/LIRGs, the hard X-rays would only trace the most compact (< 100 pc) regions with high supernova and star formation densities, therefore a lower limit to their integrated star formation. The SFR derived in NGC 5135 based on its hard X-ray luminosity is a factor of two and four lower than the values obtained from the 24 ��m and soft X-ray luminosities, respectively., Accepted for Publication in ApJ, 18 pages, 2 figures

Spectroscopic observations of Halpha and Hbeta emission lines of 128 star-forming galaxies in the redshift range 0.75, 11 pages, 9 figures, 2 tables; version addressing the referee comments

We present absorption-line index gradients for a sample of S0 galaxies in the Fornax Cluster. The sample has been selected to span a wide range in galaxy mass, and the deep VLT-FORS2 spectroscopy allows us to explore the stellar populations all the way to the outer disk-dominated regions of these galaxies. We find that globally, in both bulges and disks, star formation ceased earliest in the most massive systems, as a further manifestation of downsizing. However, within many galaxies, we find an age gradient which indicates that star formation ended first in the outermost regions. Metallicity gradients, when detected, are always negative such that the galaxy centres are more metal-rich. This finding fits with a picture in which star formation continued in the central regions, with enriched material, after it had stopped in the outskirts. Age and metallicity gradients are correlated, suggesting that large differences in star formation history between the inner and outer parts of S0 galaxies yield large differences in their chemical enrichment. In agreement with previous results, we conclude that the radial variations in the stellar populations of S0 galaxies are compatible with the hypothesis that these galaxies are the descendants of spiral galaxies whose star formation has ceased. With the addition of radial gradient information, we are able to show that this shutdown of star formation occurred from the outside inward, with the later star formation in the central regions offering a plausible mechanism for enhancing the bulge light in these systems, as the transformation to more bulge-dominated S0 galaxies requires., 9 pages, 4 figures and Appendix, accepted for publication in MNRAS

By observing the local luminous infrared galaxy NGC5135 with the near-IR IFU spectrograph SINFONI (ESO-VLT), we report an approx. 600 pc (in projection) AGN outflow traced by [SiVI]1.96mum emission. This is the largest outflow traced by a coronal line ever reported. Its large spatial scale suggests that shocks, in addition to AGN continuum emission, are needed to locally produce [SiVI] emission. We also show, for the first time, clear kinematical evidence of the AGN-outflow vs. ISM interaction through variations in the 2D velocity fields of different gas phases. Such local perturbations in the kinematics clearly match the outflow structure. We use the [FeII]1.64mum emission, a supernovae tracer, to estimate the supernovae rate in different star-forming knots (approx. 250 pc across) within the central 2.3 kpc of NGC5135. The estimated supernovae rates go from 0.02 to 0.08 yr^{-1} being in excellent agreement with predictions from 6 cm radio emission in the same areas., Comment: 6 pages, 3 figures. To appear in A.S.P. Conference Series, "Galaxy Evolution: Infrared to Millimeter Wavelength Perspective", 25-29 October 2010, Guilin, China

By observing the local luminous infrared galaxy NGC5135 with the near-IR IFU spectrograph SINFONI (ESO-VLT), we report an approx. 600 pc (in projection) AGN outflow traced by [SiVI]1.96mum emission. This is the largest outflow traced by a coronal line ever reported. Its large spatial scale suggests that shocks, in addition to AGN continuum emission, are needed to locally produce [SiVI] emission. We also show, for the first time, clear kinematical evidence of the AGN-outflow vs. ISM interaction through variations in the 2D velocity fields of different gas phases. Such local perturbations in the kinematics clearly match the outflow structure. We use the [FeII]1.64mum emission, a supernovae tracer, to estimate the supernovae rate in different star-forming knots (approx. 250 pc across) within the central 2.3 kpc of NGC5135. The estimated supernovae rates go from 0.02 to 0.08 yr^{-1} being in excellent agreement with predictions from 6 cm radio emission in the same areas.

This thesis studies the origin of local S0 galaxies and their possible links to other morphological types. To address these issues, two different approaches have been adopted: a detailed study of the stellar populations of S0s in the Fornax Cluster and a study of the Tully-Fisher Relation (TFR) of local S0s in different environments., Ph.D. Thesis submitted to The University of Nottingham, U.K. Please download the complete version at http://www.nottingham.ac.uk/~ppxapgg/phdthesis.pdf