Search

This is the fourth paper of a series investigating the AGN fuelling/feedback processes in a sample of eleven nearby low-excitation radio galaxies (LERGs). In this paper we present follow-up Atacama Large Millimeter/submillimeter Array (ALMA) observations of one source, NGC3100, targeting the $^{12}$CO(1-0), $^{12}$CO(3-2), HCO$^{+}$(4-3), SiO(3-2) and HNCO(6-5) molecular transitions. $^{12}$CO(1-0) and $^{12}$CO(3-2) lines are nicely detected and complement our previous $^{12}$CO(2-1) data. By comparing the relative strength of these three CO transitions, we find extreme gas excitation conditions (i.e. $T_{\rm ex}\gtrsim50$ K) in regions that are spatially correlated with the radio lobes, supporting the case for a jet-ISM interaction. An accurate study of the CO kinematics demonstrates that, although the bulk of the gas is regularly rotating, two distinct non-rotational kinematic components can be identified in the inner gas regions: one can be associated to inflow/outflow streaming motions induced by a two-armed spiral perturbation; the second one is consistent with a jet-induced outflow with $v_{\rm max}\approx 200$ km s$^{-1}$ and $\dot{M}\lesssim 0.12$ M$_{\odot}$ yr$^{-1}$. These values indicate that the jet-CO coupling ongoing in NGC3100 is only mildly affecting the gas kinematics, as opposed to what expected from existing simulations and other observational studies of (sub-)kpc scale jet-cold gas interactions. HCO$^{+}$(4-3) emission is tentatively detected in a small area adjacent to the base of the northern radio lobe, possibly tracing a region of jet-induced gas compression. The SiO(3-2) and HNCO(6-5) shock tracers are undetected: this - along with the tentative HCO$^{+}$(4-3) detection - may be consistent with a deficiency of very dense (i.e. $n_{\rm crit} > 10^{6}$ cm$^{-3}$) cold gas in the central regions of NGC3100., Comment: 20 pages, 11 figures, 6 tables. Accepted for publication in MNRAS

This is the third paper of a series exploring the multi-frequency properties of a sample of eleven nearby low-excitation radio galaxies (LERGs) in the southern sky. We are conducting an extensive study of different galaxy components (stars, dust, warm and cold gas, radio jets) with the aim of better understanding the AGN fuelling/feedback cycle in LERGs. Here we present new, deep, sub-kpc resolution Karl G. Jansky Very Large Array (JVLA) data for five sample sources at 10 GHz. Coupling these data with previously-acquired Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) observations and measurements of comparable quality from the literature, we carry out for the first time a full 3D analysis of the relative orientations of jet and disc rotation axes in six FR I LERGs. This analysis shows (albeit with significant uncertainties) that the relative orientation angles span a wide range ($\approx$30$^{\circ}-60^{\circ}$). There is no case where both axes are accurately aligned and there is a marginally significant tendency for jets to avoid the disc plane. Our study also provides further evidence for the presence of a jet-CO disc interaction (already inferred from other observational indicators) in at least one source, NGC 3100. In this case, the limited extent of the radio jets, along with distortions in both the molecular gas and the jet components, suggest that the jets are young, interacting with the surrounding matter and rapidly decelerating., Comment: 13 pages, 6 figures, 4 tables. Accepted for publication in MNRAS

Scaling laws of dust, HI gas and metal mass with stellar mass, specific star formation rate and metallicity are crucial to our understanding of the buildup of galaxies through their enrichment with metals and dust. In this work, we analyse how the dust and metal content varies with specific gas mass ($M_{\text{HI}}$/$M_{\star}$) across a diverse sample of 423 nearby galaxies. The observed trends are interpreted with a set of Dust and Element evolUtion modelS (DEUS) - incluidng stellar dust production, grain growth, and dust destruction - within a Bayesian framework to enable a rigorous search of the multi-dimensional parameter space. We find that these scaling laws for galaxies with $-1.0\lesssim \log M_{\text{HI}}$/$M_{\star}\lesssim0$ can be reproduced using closed-box models with high fractions (37-89$\%$) of supernova dust surviving a reverse shock, relatively low grain growth efficiencies ($\epsilon$=30-40), and long dus lifetimes (1-2\,Gyr). The models have present-day dust masses with similar contributions from stellar sources (50-80\,$\%$) and grain growth (20-50\,$\%$). Over the entire lifetime of these galaxies, the contribution from stardust ($>$90\,$\%$) outweighs the fraction of dust grown in the interstellar medium ($<$10$\%$). Our results provide an alternative for the chemical evolution models that require extremely low supernova dust production efficiencies and short grain growth timescales to reproduce local scaling laws, and could help solving the conundrum on whether or not grains can grow efficiently in the interstellar medium., Comment: 56 pages, 30 figures, accepted for publication in MNRAS

SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing program designed to investigate massive star formation and HII regions in a sample of local extended galaxies. The program will use the imaging Fourier transform spectrograph SITELLE at the Canada-France-Hawaii Telescope. Over 355 hours (54.7 nights) have been allocated beginning in fall 2018 for eight consecutive semesters. Once completed, SIGNALS will provide a statistically reliable laboratory to investigate massive star formation, including over 50 000 resolved HII regions : the largest, most complete, and homogeneous database of spectroscopically and spatially resolved extragalactic HII regions ever assembled. For each field observed, three datacubes covering the spectral bands of the filters SN1 (363 -386 nm), SN2 (482 - 513 nm), and SN3 (647 - 685 nm) are gathered. The spectral resolution selected for each spectral band is 1000, 1000, and 5000, respectively. As defined, the project sample will facilitate the study of small-scale nebular physics and many other phenomena linked to star formation at a mean spatial resolution of 20 pc. This survey also has considerable legacy value for additional topics including planetary nebulae, diffuse ionized gas, andsupernova remnants. The purpose of this paper is to present a general outlook of the survey, notably the observing strategy, galaxy sample, and science requirements., Comment: 19 pages, 14 figures, submitted to MNRAS

The properties of the dust in the cold and hot gas phases of early-type galaxies (ETGs) are key to understand ETG evolution. We thus conducted a systematic study of the dust in a large sample of local ETGs, focusing on relations between the dust and the molecular, atomic, and X-ray gas of the galaxies, as well as their environment. We estimated the dust temperatures and masses of the 260 ETGs from the ATLAS3D survey, using fits to their spectral energy distributions primarily constructed from AKARI measurements. We also used literature measurements of the cold (CO and HI) and X-ray gas phases. Our ETGs show no correlation between their dust and stellar masses, suggesting inefficient dust production by stars and/or dust destruction in X-ray gas. The global dust-to-gas mass ratios of ETGs are generally lower than those of late-type galaxies, likely due to dust-poor HI envelopes in ETGs. They are also higher in Virgo Cluster ETGs than in group and field ETGs, but the same ratios measured in the central parts of the galaxies only are independent of galaxy environment. Slow-rotating ETGs have systematically lower dust masses than fast-rotating ETGs. The dust masses and X-ray luminosities are correlated in fast-rotating ETGs, whose star formation rates are also correlated with the X-ray luminosities. The correlation between dust and X-rays in fast-rotating ETGs appears to be caused by residual star formation, while slow-rotating ETGs are likely well evolved, and thus exhausting their dust. These results appear consistent with the postulated evolution of ETGs, whereby fast-rotating ETGs form by mergers of late-type galaxies and associated bulge growth, while slow-rotating ETGs form by (dry) mergers of fast-rotating ETGs. Central cold dense gas appears to be resilient against ram pressure stripping, suggesting that Virgo Cluster ETGs may not suffer strong related star formation suppression., Comment: 18 pages, 7 figures, accepted for publication in A&A

We analyse maps of the spatially-resolved nebular emission of $\approx$1500 star-forming galaxies at $z\approx0.6$-$2.2$ from deep KMOS and MUSE observations to measure the average shape of their rotation curves. We use these to test claims for declining rotation curves at large radii in galaxies at $z\approx1$-$2$ that have been interpreted as evidence for an absence of dark matter. We show that the shape of the average rotation curves, and the extent to which they decline beyond their peak velocities, depends upon the normalisation prescription used to construct the average curve. Normalising in size by the galaxy stellar disk-scale length after accounting for seeing effects ($R_{\rm{d}}^{\prime}$), we construct stacked position-velocity diagrams that trace the average galaxy rotation curve out to $6R_{\rm{d}}^{\prime}$ ($\approx$13 kpc, on average). Combining these curves with average HI rotation curves for local systems, we investigate how the shapes of galaxy rotation curves evolve over $\approx$10 Gyr. The average rotation curve for galaxies binned in stellar mass, stellar surface mass density and/or redshift is approximately flat, or continues to rise, out to at least $6R_{\rm{d}}^{\prime}$. We find a trend between the outer slopes of galaxies' rotation curves and their stellar mass surface densities, with the higher surface density systems exhibiting flatter rotation curves. Drawing comparisons with hydrodynamical simulations, we show that the average shapes of the rotation curves for our sample of massive, star-forming galaxies at $z\approx0$-$2.2$ are consistent with those expected from $\Lambda$CDM theory and imply dark matter fractions within $6R_{\rm{d}}$ of at least $\approx60$ percent., Comment: 32 pages, 21 figures including appendices. Accepted for publication in MNRAS after addressing final comments from referee. Additional appendices added, plus some updates and additions to plots and text

We construct Tully-Fisher relations (TFRs), from large samples of galaxies with spatially-resolved H$\alpha$ emission maps from the K-band Multi-Object Spectrograph (KMOS) Redshift One Spectroscopic Survey (KROSS) at $z\approx1$. We compare these to data from the Sydney-Australian-Astronomical-Observatory Multi-object Integral-Field Spectrograph (SAMI) Galaxy Survey at $z\approx0$. We stringently match the data quality of the latter to the former, and apply identical analysis methods and sub-sample selection criteria to both to conduct a direct comparison of the absolute $K$-band magnitude and stellar mass TFRs at $z\approx1$ and $z\approx0$. We find that matching the quality of the SAMI data to that of KROSS results in TFRs that differ significantly in slope, zero-point and (sometimes) scatter in comparison to the corresponding original SAMI relations. These differences are in every case as large or larger than the differences between the KROSS $z\approx1$ and matched SAMI $z\approx0$ relations. Accounting for these differences, we compare the TFRs at $z\approx1$ and $z\approx0$. For disk-like, star-forming galaxies we find no significant difference in the TFR zero-points between the two epochs. This suggests the growth of stellar mass and dark matter in these types of galaxies is intimately linked over this $\approx8$ Gyr period., Comment: Accepted for publication in MNRAS

We analyse the velocity dispersion properties of 472 z~0.9 star-forming galaxies observed as part of the KMOS Redshift One Spectroscopic Survey (KROSS). The majority of this sample is rotationally dominated (83 +/- 5% with v_C/sigma_0 > 1) but also dynamically hot and highly turbulent. After correcting for beam smearing effects, the median intrinsic velocity dispersion for the final sample is sigma_0 = 43.2 +/- 0.8 km/s with a rotational velocity to dispersion ratio of v_C/sigma_0 = 2.6 +/- 0.1. To explore the relationship between velocity dispersion, stellar mass, star formation rate and redshift we combine KROSS with data from the SAMI survey (z~0.05) and an intermediate redshift MUSE sample (z~0.5). While there is, at most, a weak trend between velocity dispersion and stellar mass, at fixed mass there is a strong increase with redshift. At all redshifts, galaxies appear to follow the same weak trend of increasing velocity dispersion with star formation rate. Our results are consistent with an evolution of galaxy dynamics driven by disks that are more gas rich, and increasingly gravitationally unstable, as a function of increasing redshift. Finally, we test two analytic models that predict turbulence is driven by either gravitational instabilities or stellar feedback. Both provide an adequate description of the data, and further observations are required to rule out either model., Comment: Accepted for publication in MNRAS. Data available at http://astro.dur.ac.uk/KROSS

As a part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM) project, we present an estimate of the mass of the supermassive black hole (SMBH) in the nearby fast-rotator early-type galaxy NGC 3665. We obtained Combined Array for Research in Millimeter Astronomy (CARMA) B and C array observations of the $^{12}$CO$(J=2-1)$ emission line with a combined angular resolution of $0".59$. We analysed and modelled the three-dimensional molecular gas kinematics, obtaining a best-fit SMBH mass $M_{\rm BH}=5.75^{+1.49}_{-1.18} \times 10^{8}$ $M_{\odot}$, a mass-to-light ratio at $H$-band $(M/L)_{H}=1.45\pm0.04$ $(M/L)_{\odot, H}$, and other parameters describing the geometry of the molecular gas disc (statistical errors, all at $3\sigma$ confidence). We estimate the systematic uncertainties on the stellar $M/L$ to be $\approx0.2$ $(M/L)_{\odot, H}$, and on the SMBH mass to be $\approx0.4\times10^{8}$ $M_{\odot}$. The measured SMBH mass is consistent with that estimated from the latest correlations with galaxy properties. Following our older works, we also analysed and modelled the kinematics using only the major-axis position-velocity diagram, and conclude that the two methods are consistent., Comment: Accepted to MNRAS

We present dynamical measurements for 586 H-alpha detected star-forming galaxies from the KMOS (K-band Multi-Object Spectrograph) Redshift One Spectroscopic Survey (KROSS). The sample represents typical star-forming galaxies at this redshift (z=0.6-1.0), with a median star formation rate of ~7 Msol/yr and a stellar mass range of log[M/Msol]~9-11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully-Fisher relationship) for our rotationally-dominated sources (v/sigma>1) has a consistent slope and normalisation as that observed for z=0 disks. In contrast, the specific angular momentum (j; angular momentum divided by stellar mass), is ~0.2-0.3 dex lower on average compared to z=0 disks. The specific angular momentum scales as M^[0.6+/-0.2], consistent with that expected for dark matter (i.e., proportional to M^[2/3]). We find that z~0.9 star-forming galaxies have decreasing specific angular momentum with increasing Sersic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disk-dominated morphologies. This implies that an angular momentum-mass-morphology relationship, similar to that observed in local massive galaxies, is already in place by z~1., Comment: Accepted for publication in MNRAS. Table of values and extended figures available at: http://astro.dur.ac.uk/KROSS/

We present first results from the KMOS Redshift One Spectroscopic Survey (KROSS), an ongoing large kinematical survey of a thousand, z~1 star forming galaxies, with VLT KMOS. Out of the targeted galaxies (~500 so far), we detect and spatially resolve Ha emission in ~90% and 77% of the sample respectively. Based on the integrated Ha flux measurements and the spatially resolved maps we derive a median star formation rate (SFR) of ~7.0 Msun/yr and a median physical size of = 5.1kpc. We combine the inferred SFRs and effective radii measurements to derive the star formation surface densities ({\Sigma}SFR) and present a "resolved" version of the star formation main sequence (MS) that appears to hold at sub-galactic scales, with similar slope and scatter as the one inferred from galaxy integrated properties. Our data also yield a trend between {\Sigma}SFR and {\Delta}(sSFR) (distance from the MS) suggesting that galaxies with higher sSFR are characterised by denser star formation activity. Similarly, we find evidence for an anti-correlation between the gas phase metallicity (Z) and the {\Delta}(sSFR), suggesting a 0.2dex variation in the metal content of galaxies within the MS and significantly lower metallicities for galaxies above it. The origin of the observed trends between {\Sigma}SFR - {\Sigma}(sSFR) and Z - {\Delta}(sSFR) could be driven by an interplay between variations of the gas fraction or the star formation efficiency of the galaxies along and off the MS. To address this, follow-up observations of the our sample that will allow gas mass estimates are necessary., Comment: Accepted for publication in MNRAS, ref. MN-15-2214-MJ.R2 14/12/15)

We present a study of the cold gas contents of the Atlas3D early-type galaxies, in the context of their optical colours, near-UV colours, and H\beta\ absorption line strengths. Early-type (elliptical and lenticular) galaxies are not as gas-poor as previously thought, and at least 40% of local early-type galaxies are now known to contain molecular and/or atomic gas. This cold gas offers the opportunity to study recent galaxy evolution through the processes of cold gas acquisition, consumption (star formation), and removal. Molecular and atomic gas detection rates range from 10% to 34% in red sequence early-type galaxies, depending on how the red sequence is defined, and from 50% to 70% in blue early-type galaxies. Notably, massive red sequence early-type galaxies (stellar masses > 5e10 Msun, derived from dynamical models) are found to have HI masses up to M(HI)/Mstar ~ 0.06 and H_2 masses up to M(H$_2$)/Mstar ~ 0.01. Some 20% of all massive early-type galaxies may have retained atomic and/or molecular gas through their transition to the red sequence. However, kinematic and metallicity signatures of external gas accretion (either from satellite galaxies or the intergalactic medium) are also common, particularly at stellar masses <= 5e10 Msun, where such signatures are found in ~ 50% of H$_2$-rich early-type galaxies. Our data are thus consistent with a scenario in which fast rotator early-type galaxies are quenched former spiral galaxies which have undergone some bulge growth processes, and in addition, some of them also experience cold gas accretion which can initiate a period of modest star formation activity. We discuss implications for the interpretation of colour-magnitude diagrams., Comment: 20 pages. Accepted for publication in MNRAS

We present a detailed two-dimensional stellar dynamical analysis of a sample of 44 cosmological hydrodynamical simulations of individual central galaxies and their satellites. Kinematic maps of the stellar line-of-sight velocity, velocity dispersion, and higher-order Gauss-Hermite moments $h_3$ and $h_4$ are constructed for each central galaxy and for the most massive satellites. The amount of rotation is quantified using the $\lambda_{\mathrm{R}}$-parameter. The velocity, velocity dispersion, $h_3$, and $h_4$ fields of the simulated galaxies show a diversity similar to observed kinematic maps of early-type galaxies in the ATLAS$^{\rm{3D}}$ survey. This includes fast (regular), slow, and misaligned rotation, hot spheroids with embedded cold disk components as well as galaxies with counter-rotating cores or central depressions in the velocity dispersion. We link the present day kinematic properties to the individual cosmological formation histories of the galaxies. In general, major galaxy mergers have a significant influence on the rotation properties resulting in both a spin-down as well as a spin-up of the merger remnant. Lower mass galaxies with significant in-situ formation of stars, or with additional gas-rich major mergers - resulting in a spin-up - in their formation history, form elongated fast rotators with a clear anti-correlation of $h_3$ and $v/\sigma$. An additional formation path for fast rotators includes gas poor major mergers leading to a spin-up of the remnants. This formation path does not result in anti-correlated $h_3$ and $v/\sigma$. The galaxies most consistent with the rare class of non-rotating round early-type galaxies grow by gas-poor minor mergers alone. In general, more massive galaxies have less in-situ star formation since $z \sim 2$, rotate slower and have older stellar populations. (shortened), Comment: Accepted for publication in MNRAS

We use multi-wavelength (0.12 - 500 micron) photometry from Herschel-ATLAS, WISE, UKIDSS, SDSS and GALEX, to study 23 nearby spheroidal galaxies with prominent dust lanes (DLSGs). DLSGs are considered to be remnants of recent minor mergers, making them ideal laboratories for studying both the interstellar medium (ISM) of spheroids and minor-merger-driven star formation in the nearby Universe. The DLSGs exhibit star formation rates (SFRs) between 0.01 and 10 MSun yr^-1, with a median of 0.26 MSun yr^-1 (a factor of 3.5 greater than the average SG). The median dust mass, dust-to-stellar mass ratio and dust temperature in these galaxies are around 10^7.6 MSun yr^-1, ~0.05% and ~19.5 K respectively. The dust masses are at least a factor of 50 greater than that expected from stellar mass loss and, like the SFRs, show no correlation with galaxy luminosity, suggesting that both the ISM and the star formation have external drivers. Adopting literature gas-to-dust ratios and star formation histories derived from fits to the panchromatic photometry, we estimate that the median current and initial gas-to-stellar mass ratios in these systems are ~4% and ~7% respectively. If, as indicated by recent work, minor mergers that drive star formation in spheroids with (NUV-r)>3.8 (the colour range of our DLSGs) have stellar mass ratios between 1:6 and 1:10, then the satellite gas fractions are likely >50%., Comment: MNRAS in press

For early-type galaxies, the ability to sustain a corona of hot, X-ray emitting gas could have played a key role in quenching their star-formation history. Yet, it is still unclear what drives the precise amount of hot gas around these galaxies. By combining photometric and spectroscopic measurements for the early-type galaxies observed during the Atlas3D integral-field survey with measurements of their X-ray luminosity based on X-ray data of both low and high spatial resolution we conclude that the hot-gas content of early-type galaxies can depend on their dynamical structure. Specifically, whereas slow rotators generally have X-ray halos with luminosity L_X,gas and temperature T values that are in line with what is expected if the hot-gas emission is sustained by the thermalisaton of the kinetic energy carried by the stellar-mass loss material, fast rotators tend to display L_X,gas values that fall consistently below the prediction of this model, with similar T values that do not scale with the stellar kinetic energy as observed in the case of slow rotators. Considering that fast rotators are likely to be intrinsically flatter than slow rotators, and that the few L_X,gas-deficient slow rotators also happen to be relatively flat, the observed L_X,gas deficiency in these objects would support the hypothesis whereby flatter galaxies have a harder time in retaining their hot gas. We discuss the implications that a different hot-gas content could have on the fate of both acquired and internally-produced gaseous material, considering in particular how the L_X,gas deficiency of fast rotators would make them more capable to recycle the stellar-mass loss material into new stars than slow rotators. This is consistent with the finding that molecular gas and young stars are detected only in fast rotators in the Atlas3D sample, and that fast rotators tend to dustier than slow rotators. [Abridged], Comment: 16 pages, 10 figures, accepted for publications on MNRAS. More information about our Atlas3D project see http://www-astro.physics.ox.ac.uk/atlas3d/

We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS3D survey (Cappellari et al. 2011) and how it plays host to an AGN-driven molecular outflow, potentially quenching all of its star formation (SF) within the next 100 Myr. While major mergers appear to play a role in instigating outflows in other systems, deep imaging of NGC 1266 as well as stellar kinematic observations from SAURON, have failed to provide evidence that NGC 1266 has recently been involved in a major interaction. The molecular gas and the instantaneous SF tracers indicate that the current sites of star formation are located in a hypercompact disk within 200 pc of the nucleus (Fig. 1; SF rate ~ 2 Msuns/yr). On the other hand, tracers of recent star formation, such as the H{\beta} absorption map from SAURON and stellar population analysis show that the young stars are distributed throughout a larger area of the galaxy than current star formation. As the AGN at the center of NGC 1266 continues to drive cold gas out of the galaxy, we expect star formation rates to decline as the star formation is ultimately quenched. Thus, NGC 1266 is in the midst of a key portion of its evolution and continued studies of this unique galaxy may help improve our understanding of how galaxies transition from the blue to the red sequence (Alatalo et al. 2011)., Comment: 1 page, Proceedings IAU symposium No. 292: Molecular gas, dust and star formation in galaxies, ed. by Tony Wong and Juergen Ott

NGC 1266 is a nearby field galaxy observed as part of the ATLAS3D survey (Cappellari et al. 2011). NGC 1266 has been shown to host a compact (< 200 pc) molecular disk and a mass-loaded molecular outflow driven by the AGN (Alatalo et al. 2011). Very Long Basline Array (VLBA) observations at 1.65 GHz revealed a compact (diameter < 1.2 pc), high bright- ness temperature continuum source most consistent with a low-level AGN origin. The VLBA continuum source is positioned at the center of the molecular disk and may be responsible for the expulsion of molecular gas in NGC 1266. Thus, the candidate AGN-driven molecular outflow in NGC 1266 supports the picture in which AGNs do play a significant role in the quenching of star formation and ultimately the evolution of the red sequence of galaxies., Comment: 2 pages, Proceedings from IAU Symposium 290: Feeding compact objects, Accretion on all scales

We study the volume-limited and nearly mass selected (stellar mass M>6*10^9 Msun) Atlas3D sample of 260 early-type galaxies. We construct detailed axisymmetric dynamical models (JAM), which allow for orbital anisotropy, include a dark matter halo, and reproduce in detail both the galaxy images and the high-quality integral-field stellar kinematics. We derive accurate total M/L and dark matter fractions f_DM, within a sphere of radius r=Re. We also measure the stellar M/L and derive a median dark matter fraction f_DM=13%. We find that the thin two-dimensional subset spanned by galaxies in the (M_JAM,sigma_e,R_e) coordinates system, which we call the Mass Plane (MP) has an observed rms scatter of 19% and an intrinsic one of 11%. The MP satisfies the scalar virial relation M_JAM sigma_e^2 R_e within our tight errors. However, the details of how both Re and sigma_e are determined are critical in defining the precise deviation from the virial exponents. We revisit the (M/L)-sigma_e relation, which describes most of the deviations between the MP and the FP. The best-fitting relation is (M/L) sigma_e^0.72 (r-band). It provides an upper limit to any systematic increase of the IMF mass normalization with sigma_e. We study of the link between sigma_e and the galaxies circular velocity V_circ within 1Re (where stars dominate) and find the relation max(V_circ)~1.76*sigma_e, which has an observed scatter of 7%. The accurate parameters described in this paper are used in the companion Paper XX of this series to explore the variation of global galaxy properties, including the IMF, on the projections of the MP. [Abridged], Comment: 35 pages, 18 figures, LaTeX. Accepted for publication in MNRAS. Includes a new data table and figures of all dynamical models. More information about our Atlas3D project is available at http://purl.org/atlas3d

We study the (M,sigma) and (M,Re) projections of the thin Mass Plane (MP) (M,sigma,Re) which describes the distribution of the galaxy population. The distribution of galaxy properties on the MP is characterized by: (i) a zone of exclusion described by two power-laws joined by a break at M 3e10 Msun. This results in a break in the mean M-sigma relation with Msigma^2.3 and M sigma^4.7 at small and large sigma respectively; (ii) a mass M 2e11 Msun which separates a population dominated by flat fast rotator with disks and spiral galaxies at lower masses, from one dominated by quite round slow rotators at larger masses; (iii) below that mass the distribution of ETGs properties tends to be constant along lines of constant sigma; (iv) it forms a parallel sequence with the distribution of spiral galaxies; (v) at even lower masses, the distribution of fast rotator ETGs and late spirals naturally extends to that of dwarf ETGs (Sph) and dwarf irregulars (Im) respectively. We show via dynamical models that sigma traces the bulge fraction, which drives the observed trends in M/L, Hbeta, colour, IMF and molecular gas fraction. We interpret this as due to a combination of two main effects: (i) an increase of the bulge fraction which increases sigma and greatly enhances the likelihood for a galaxy to have its star formation quenched, and (ii) dry merging, increasing galaxy mass along lines of nearly constant sigma, while leaving the population unchanged. [Abriged], Comment: 35 pages, 16 figure, LaTeX. Accepted for publication in MNRAS. Includes a new data table. More information about our Atlas3D project is available at http://purl.org/atlas3d

Much of our knowledge of galaxies comes from analysing the radiation emitted by their stars. It depends on the stellar initial mass function (IMF) describing the distribution of stellar masses when the population formed. Consequently knowledge of the IMF is critical to virtually every aspect of galaxy evolution. More than half a century after the first IMF determination, no consensus has emerged on whether it is universal in different galaxies. Previous studies indicated that the IMF and the dark matter fraction in galaxy centres cannot be both universal, but they could not break the degeneracy between the two effects. Only recently indications were found that massive elliptical galaxies may not have the same IMF as our Milky Way. Here we report unambiguous evidence for a strong systematic variation of the IMF in early-type galaxies as a function of their stellar mass-to-light ratio, producing differences up to a factor of three in mass. This was inferred from detailed dynamical models of the two-dimensional stellar kinematics for the large Atlas3D representative sample of nearby early-type galaxies spanning two orders of magnitude in stellar mass. Our finding indicates that the IMF depends intimately on a galaxy's formation history., Comment: 4 pages, 2 figures, LaTeX. Accepted for publication as a Nature Letter. More information about our Atlas3D project is available at http://purl.org/atlas3d

[Abridged] We present ground-based MDM V-band and Spitzer/IRAC 3.6um-band photometric observations of the 72 representative galaxies of the SAURON Survey. In combination with the SAURON stellar velocity dispersion measured within an effective radius (se), this allows us to explore the location of our galaxies in the main scaling relations. We investigate the dependence of these relations on our recent kinematical classification of early-type galaxies (i.e. Slow/Fast Rotators) and the stellar populations. Slow Rotator and Fast Rotator E/S0 galaxies do not populate distinct locations in the scaling relations, although Slow Rotators display a smaller intrinsic scatter. Surprisingly, extremely young objects do not display the bluest (V-[3.6]) colours in our sample, as is usually the case in optical colours. This can be understood in the context of the large contribution of TP-AGB stars to the infrared, even for young populations, resulting in a very tight (V-[3.6]) - se relation that in turn allows us to define a strong correlation between metallicity and velocity dispersion. Many Sa galaxies appear to follow the Fundamental Plane defined by E/S0 galaxies. Galaxies that appear offset from the relations correspond mostly to objects with extremely young populations, with signs of on-going, extended star formation. We correct for this effect in the Fundamental Plane, by replacing luminosity with stellar mass using an estimate of the stellar mass-to-light ratio, so that all galaxies are part of a tight, single relation. The new estimated coefficients are consistent in both photometric bands and suggest that differences in stellar populations account for about half of the observed tilt with respect to the virial prediction. After these corrections, the Slow Rotator family shows almost no intrinsic scatter around the best-fit Fundamental Plane., Comment: Accepted for publication in MNRAS. 32 pages, 20 figures, LaTeX

We look at the morphology of fast and slow rotator early-type galaxies. Edge-on fast rotators are lenticular galaxies. They appear like spiral galaxies with the gas and dust removed, and in some cases are flat ellipticals with disky isophotes. Fast rotators are often barred and span the same full range of bulge fractions as spiral galaxies. The slow rotators are rounder and are generally consistent with being genuine, namely spheroidal-like, elliptical galaxies. We propose a revision to the tuning-fork diagram by Hubble as it gives a misleading description of ETGs. We study for the first time the kinematic morphology-density T-Sigma relation using fast and slow rotators to replace lenticulars and ellipticals. We find that our relation is cleaner than using classic morphology. Slow rotators are nearly absent at the lowest density environments [f(SR)<2%] and generally constitute a small fraction [f(SR)~4%] of the total galaxy population in the environments explored by our survey, with the exception of the densest core of the Virgo cluster [f(SR)~20%]. We find a clean log-linear relation between the fraction f(Sp) of spiral galaxies and the local galaxy surface density. The existence of a smooth kinematic T-Sigma relation in the field excludes processes related to the cluster environment as main contributors to the apparent conversion of spirals into fast-rotators in low-density environments. It shows that the segregation is driven by local effects at the small-group scale. Only at the largest densities in the Virgo core does the f(Sp) relation break down and steepens sharply, while the fraction of slow-rotators starts to significantly increase. This suggests that a different mechanism is at work there. (Abridged), Comment: 18 pages, 9 figures, LaTeX. Accepted for publication in MNRAS on 24 February 2011

The molecular gas content of local early-type galaxies is constrained and discussed in relation to their evolution. First, as part of the Atlas3D survey, we present the first complete, large (260 objects), volume-limited single-dish survey of CO in normal local early-type galaxies. We find a surprisingly high detection rate of 22%, independent of luminosity and at best weakly dependent on environment. Second, the extent of the molecular gas is constrained with CO synthesis imaging, and a variety of morphologies is revealed. The kinematics of the molecular gas and stars are often misaligned, implying an external gas origin in over a third of the systems, although this behaviour is drastically diffferent between field and cluster environments. Third, many objects appear to be in the process of forming regular kpc-size decoupled disks, and a star formation sequence can be sketched by piecing together multi-wavelength information on the molecular gas, current star formation, and young stars. Last, early-type galaxies do not seem to systematically obey all our usual prejudices regarding star formation, following the standard Schmidt-Kennicutt law but not the far infrared-radio correlation. This may suggest a greater diversity in star formation processes than observed in disk galaxies. Using multiple molecular tracers, we are thus starting to probe the physical conditions of the cold gas in early-types., Comment: Proceedings of the IAU Symposium 277 "Tracing the Ancestry of Galaxies". 4 pages, 3 figures

The mass assembly of galaxies leaves various imprints on their surroundings, such as shells, streams and tidal tails. The frequency and properties of these fine structures depend on the mechanism driving the mass assembly: e.g. a monolithic collapse, rapid cold-gas accretion followed by violent disk instabilities, minor mergers or major dry / wet mergers. Therefore, by studying the outskirts of galaxies, one can learn about their main formation mechanism. I present here our on-going work to characterize the outskirts of Early-Type Galaxies (ETGs), which are powerful probes at low redshift of the hierarchical mass assembly of galaxies. This work relies on ultra-deep optical images obtained at CFHT with the wide-field of view MegaCam camera of field and cluster ETGs obtained as part of the Atlas-3D and NGVS projects. State of the art numerical simulations are used to interpret the data. The images reveal a wealth of unknown faint structures at levels as faint as 29 mag arcsec-2 in the g-band. Initial results for two galaxies are presented here., Comment: 4 pages, 3 figures, proceedings of the IAU Symposium 277, tracing the ancestry of galaxies

The Atlas3D project is a multi-wavelength survey combined with a theoretical modeling effort. The observations span from the radio to the millimeter and optical, and provide multi-colour imaging, two-dimensional kinematics of the atomic (HI), molecular (CO) and ionized gas (Hbeta, [OIII] and [NI]), together with the kinematics and population of the stars (Hbeta, Fe5015 and Mgb), for a carefully selected, volume-limited (1.16*10^5 Mpc^3) sample of 260 early-type (elliptical E and lenticular S0) galaxies (ETGs). The models include semi-analytic, N-body binary mergers and cosmological simulations of galaxy formation. Here we present the science goals for the project and introduce the galaxy sample and the selection criteria. The sample consists of nearby (D<42 Mpc) morphologically-selected ETGs extracted from a parent sample of 871 galaxies (8% E, 22% S0 and 70% spirals) brighter than M_K<-21.5 mag (stellar mass M_Star>6*10^9 M_Sun). We analyze possible selection biases and we conclude that the parent sample is essentially complete and statistically representative of the nearby galaxy population. We present the size-luminosity relation for the spirals and ETGs and show that the ETGs in the Atlas3D sample define a tight red sequence in a colour-magnitude diagram, with few objects in the transition from the blue cloud. We describe the strategy of the SAURON integral-field observations and the extraction of the stellar kinematics with the pPXF method. We give an overview of the characteristics of the other main datasets already available for our sample and of the ongoing modelling projects., Comment: 27 pages, 11 figures, LaTeX. Accepted for publication in MNRAS

In a pilot project to study the relationship between star formation and molecular gas properties in nearby normal early-type galaxies, we used the IRAM 30m telescope to observe the 13CO(J=1-0), 13CO(J=2-1), HCN(J=1-0) and HCO+(J=1-0) line emission in the four galaxies of the SAURON sample with the strongest 12CO emission. We report the detection of 13CO emission in all four SAURON sources and HCN emission in three sources, while no HCO+ emission was found to our detection limits in any of the four galaxies. We find that the 13CO/12CO ratios of three SAURON galaxies are somewhat higher than those in galaxies of different Hubble types. The HCN/12CO and HCN/13CO ratios of all four SAURON galaxies resemble those of nearby Seyfert and dwarf galaxies with normal star formation rates, rather than those of starburst galaxies. The HCN/HCO+ ratio is found to be relatively high (i.e., >1) in the three SAURON galaxies with detected HCN emission, mimicking the behaviour in other star-forming galaxies but being higher than in starburst galaxies. When compared to most galaxies, it thus appears that 13CO is enhanced (relative to 12CO) in three out of four SAURON galaxies and HCO+ is weak (relative to HCN) in three out of three galaxies. All three galaxies detected in HCN follow the standard HCN-infrared luminosity and dense gas fraction-star formation efficiency correlations. As already suggested by 12CO observations, when traced by infrared radiation, star formation in the three SAURON galaxies thus appears to follow the same physical laws as in galaxies of different Hubble types. The star formation rate and fraction of dense molecular gas however do not reach the high values found in nearby starburst galaxies, but rather resemble those of nearby normal star-forming galaxies., Comment: accepted for publication in MNRAS; abbreviated abstract to match character limit by astroph; 8 pages, 3 figures, 4 tables

We study resolution effects in numerical simulations of gas-rich and gas-poor major mergers, and show that the formation of slowly-rotating elliptical galaxies often requires a resolution that is beyond the present-day standards to be properly modelled. Our sample of equal-mass merger models encompasses various masses and spatial resolutions, ranging from about 200pc and 10^5 particles per component, typical of some recently published major merger simulations, to up to 32pc and 10^3 M_sun in simulations using 2.4 x 10^7 collisionless particles and 1.2 x 10^7 gas particles, among the highest resolutions reached so far for gas-rich major merger of massive disc galaxies. We find that the formation of fast-rotating early-type galaxies, that are flattened by a significant residual rotation, is overall correctly reproduced at all such resolutions. However, the formation of slow-rotating early-type galaxies, which have a low residual angular momentum and are supported mostly by anisotropic velocity dispersions, is strongly resolution-dependent. The evacuation of angular momentum from the main stellar body is largely missed at standard resolution, and systems that should be slow rotators are then found to be fast rotators. The effect is most important for gas-rich mergers, but is also witnessed in mergers with an absent or modest gas component. The effect is robust with respect to our initial conditions and interaction orbits, and originates in the physical treatment of the relaxation process during the coalescence of the galaxies. Our findings show that a high-enough resolution is required to accurately model the global properties of merger remnants and the evolution of their angular momentum. The role of gas-rich mergers of spiral galaxies in the formation of slow-rotating ellipticals may therefore have been underestimated., Comment: Accepted by MNRAS, 16 pages, 14 figures. Resolutions of the figures have been significantly reduced.

We present a preliminary analysis of the HI properties of early-type galaxies in the ATLAS3D sample. Using WSRT data for ~100 galaxies outside the Virgo cluster and data from the Alfalfa project for galaxies inside Virgo, we discuss the dependence of HI properties on environment. We detect HI in about half of the galaxies outside Virgo. For these systems, the HI morphology and kinematics change as a function of environment, going from regular, rotating systems around isolated galaxies to progressively more disturbed structures for galaxies with neighbours or in groups. In denser environment, inside Virgo, nearly none of the galaxies contains HI. We discuss future work in this field which will be enabled by next-generation, pre-SKA radio instruments. We present a simulated Apertif HI observation of an ATLAS3D early-type galaxy, showing how its appearance and detection level vary as a function of redshift., Comment: In the proceedings of the "Panoramic Radio Astronomy" conference held on 2-5 June 2009 in Groningen, the Netherlands. 6 pages, 3 figures; reference added

We study the origin of the scaling relations of early-type galaxies (ETGs) by constructing detailed models of the stellar dynamics for the K-band selected, volume-limited ATLAS3D sample of 263 nearby ETGs, spanning a large range of masses and stellar velocity dispersions (60 < sigma < 350 km/s)., Comment: 1 page, no figures, LaTeX. Invited talk to Joint Discussion 01 "Dark Matter in Early-Type Galaxies". To appear in Highlights of Astronomy, Vol. 15, Proc. of the XXVIIth IAU General Assembly, Rio de Janeiro, Brazil, August 2009, eds. L. V. E. Koopmans & T. Treu, Cambridge University Press

Using the unique dataset obtained within the course of the SAURON project, a radically new view of the structure, dynamics and stellar populations of early-type galaxies has emerged. We show that galaxies come in two broad flavours (slow and fast rotators), depending on whether or not they exhibit clear large-scale rotation, as indicated via a robust measure of the specific angular momentum of baryons. This property is also linked with other physical characteristics of early-type galaxies, such as: the presence of dynamically decoupled cores, orbital structure and anisotropy, stellar populations and dark matter content. I here report on the observed link between this baryonic angular momentum and a mass sequence, and how this uniquely relates to the building of the red sequence via dissipative/dissipationless mergers and secular evolution., Comment: 4 pages, 1 figure. To appear in the Proceedings of IAU Symposium 245 "Formation and Evolution of Galaxy Bulges", Eds M. Bureau, E. Athanassoula, and B. Barbuy

As part of an effort to enlarge the number of well-studied Magellanic-type galaxies, we obtained broadband optical imaging and neutral hydrogen radio synthesis observations of the dwarf irregular galaxy ESO 364-G 029. The optical morphology characteristically shows a bar-like main body with a one-sided spiral arm, an approximately exponential light distribution, and offset photometric and kinematic centers. The HI distribution is mildly asymmetric and, although slightly offset from the photometric center, roughly follows the optical brightness distribution, extending to over 1.2 Holmberg radii (where mu_B = 26.5 mag/arcsec^2). In particular, the highest HI column densities closely follow the bar, one-arm spiral, and a third optical extension. The rotation is solid-body in the inner parts but flattens outside of the optical extent. The total HI flux F_HI = 23.1 pm 1.2 Jy km/s, yielding a total HI mass M_HI= (6.4 pm 1.7) x 10^8 Msun (for a distance D = 10.8 pm 1.4 Mpc) and a total HI mass-to-blue-luminosity ratio M_HI/L_B = (0.96 pm 0.14) Msun / Lsun,B (distance independent). The HI data suggest a very complex small-scale HI structure, with evidence of large shells and/or holes, but deeper observations are required for a detailed study. Follow-up observations are also desirable for a proper comparison with the Large Magellanic Cloud, where despite an optical morphology very similar to ESO 364-G 029 the HI bears little resemblance to the optical., Comment: 10 pages, 11 figures, accepted by A&A

We present the results of a survey of CO emission in 43 of the 48 representative E/S0 galaxies observed in the optical with the SAURON integral-field spectrograph. The CO detection rate is 12/43 or 28%. This is lower than previous studies of early-types but can probably be attributed to different sample selection criteria. As expected, earlier type, more luminous and massive galaxies have a relatively lower molecular gas content. We find that CO-rich galaxies tend to have higher H\beta but lower Fe5015 and Mgb absorption indices than CO-poor galaxies. Those trends appear primarily driven by the age of the stars, an hypothesis supported by the fact that the galaxies with the strongest evidence of star formation are also the most CO-rich. In fact, the early-type galaxies from the current sample appear to extend the well-known correlations between FIR luminosity, dust mass and molecular mass of other galaxy types. The star formation interpretation is also consistent with the SAURON galaxies' radio continuum and FIR flux ratios, and their inferred star formation efficiencies are similar to those in spiral galaxies. It thus appears that we have identified the material fueling (residual) star formation in early-type galaxies, and have demonstrated that it is actively being transformed. Nevertheless, the lack of strong correlations between the CO content and most stellar parameters is compatible with the idea that, in a significant number of sample galaxies, the molecular gas has been accreted from the outside and has properties rather independent from the old, pre-existing stellar component., Comment: 14 pages, 9 figures, accepted in MNRAS

We analyse the orbital distribution of E and S0 galaxies using SAURON integral-field stellar kinematics. We construct the anisotropy (V/sigma,epsilon) diagram, for the 48 E/S0 galaxies from the SAURON survey. For a subsample of 24 galaxies consistent with axisymmetry, we use three-integral axisymmetric Schwarzschild dynamical models to recover the detailed orbital distribution and we find good agreement with the anisotropy derived from the (V/sigma,epsilon) diagram. In the companion Paper IX we show that the early-type galaxies can be subdivided into two classes of systems with or without a significant amount of specific stellar angular momentum. Here we show that the two classes have different distributions on the (V/sigma,epsilon) diagram. The slow rotators are more common among the most massive systems and are generally classified as E from photometry alone. Those in our sample tend to be fairly round (epsilon<0.3), but can have significant kinematical misalignments, indicating that as a class they are moderately triaxial, and span a range of anisotropies (delta<0.3). The fast rotators are generally fainter and are classified either E or S0. They can appear quite flattened (epsilon<0.7), do not show significant kinematical misalignments (unless barred or interacting), indicating they are nearly axisymmetric, and span an even larger range of anisotropies (delta<0.5). These results are confirmed when we extend our analysis to 18 additional E/S0 galaxies observed with SAURON. All these results support the idea that fast rotators are nearly oblate and contain disk-like components. The role of gas must have been important for their formation. The slow rotators are weakly triaxial. Current collisionless merger models seem unable to explain their detailed observed properties. (Abridged), Comment: 27 pages, 22 figures, LaTeX. Accepted for publication in MNRAS

2D stellar kinematics of 48 representative E and S0 galaxies obtained with the SAURON IFS reveal that early-type galaxies appear in two broad flavours, depending on whether they exhibit clear large-scale rotation or not. We define a new parameter LambdaR which involves luminosity weighted averages over the full 2D kinematic field, as a proxy to quantify the observed projected stellar angular momentum per unit mass. We use it as a basis for a new kinematic classification: early-type galaxies are separated into slow and fast rotators (SRs, FRs), depending on whether they have LambdaR values within their effective radius Re below or above 0.1, respectively. SRs and FRs are shown to be physically distinct classes of galaxies, a result which cannot simply be the consequence of a biased viewing angle. FRs tend to be relatively low luminosity galaxies. SRs tend to be brighter and more massive galaxies, but are still spread over a wide range of absolute magnitude. 3 slow rotators of our sample, among the most massive ones, are consistent with zero rotation. Remarkably, all other SRs contain a large kpc-scale KDC. All FRs show well aligned photometric and kinemetric axes, and small velocity twists, in contrast with most SRs which exhibit significant misalignments and velocity twists. In a companion paper (Paper X), we also show that FRs and SRs are distinct classes in terms of their orbital distribution. We suggest that gas is a key ingredient in the formation and evolution of FRs, and that the slowest rotators are the extreme evolutionary end point reached deep in gravitational potential wells where dissipationless mergers had a major role in the evolution, and for which most of the baryonic angular momentum was expelled outwards. (abridged), Comment: Accepted for publication in MNRAS, 18 pages, 13 figures. Paper with Figure 1 at full resolution available at http://cral.univ-lyon1.fr/eric.emsellem/labo/perso/Preprints.html. (3 numbers and one corrected figure in new version, consistent with the published one)

We present high spatial resolution integral-field spectroscopy of 28 elliptical (E) and lenticular (S0) galaxies from the SAURON representative survey obtained with the OASIS spectrograph during its operation at the CFHT. These seeing-limited observations explore the central 8"x10" (typically one kiloparsec diameter) regions of these galaxies using a spatial sampling four times higher than SAURON (0.27" vs. 0.94" spatial elements), resulting in almost a factor of two improvement in the median PSF. These data allow accurate study of the central regions to complement the large-scale view provided by SAURON. Here we present the stellar and gas kinematics, stellar absorption-line strengths and nebular emission-line strengths for this sample. We also characterise the stellar velocity maps using the "kinemetry" technique, and derive maps of the luminosity-weighted stellar age, metallicity and abundance ratio via stellar population models. We give a brief review of the structures found in our maps, linking also to larger-scale structures measured with SAURON. We present two previously unreported kinematically-decoupled components (KDCs) in the centres of NGC3032 and NGC4382. We compare the intrinsic size and luminosity-weighted stellar age of all the visible KDCs in the full SAURON sample, and find two types of components: kiloparsec-scale KDCs, which are older than 8 Gyr, and are found in galaxies with little net rotation; and compact KDCs, which have intrinsic diameters of less than a few hundred parsec, show a range of stellar ages from 0.5 - 15 Gyr (with 5/6 younger than 5 Gyr), are found exclusively in fast-rotating galaxies, and are close to counter-rotating around the same axis as their host. (abridged), Comment: 58 pages, 43 figures. Accepted for publication in MNRAS. A version with full resolution figures is available at http://www.strw.leidenuniv.nl/sauron/

Kn-band images, unsharp-masked images, as well as major-axis and vertically- summed surface brightness profiles are presented for 30 edge-on spiral galaxies, most with a boxy or peanut-shaped (B/PS) bulge. Such galaxies have more complex morphologies than galaxies of other bulge types, more often showing (off-)centered X structures, secondary major-axis maxima and spiral-like structures. Those features are also observed in N-body simulations of barred discs and may trace the main bar orbit families. The surface brightness profiles of galaxies with a B/PS bulge are also more complex, with typically 3 or more clearly separated regions, including a flat intermediate region (Freeman Type II profiles). Those radial breaks offer evidence for bar-driven transfer of angular momentum and radial redistribution of material. The profiles also suggest a rapid variation of the scaleheight of the disc material, contrary to conventional wisdom but again as expected from vertical resonances and instabilities in barred discs. The steep inner region of the surface brightness profiles is often shorter than the isophotally thick part of the galaxies, itself always shorter than the flat region of the profiles. Contrary to the standard `bulge + disc' model, we thus propose that galaxies with a B/PS bulge are composed of a thin concentrated disc (a disc-like bulge) contained within a partially thick bar (the B/PS bulge) and a thin outer disc. The inner disc likely formed secularly through bar-driven processes and is responsible for the steep inner region of the surface brightness profiles, while the bar is responsible for the flat region and the thick complex morphological structures observed. Those components are strongly coupled dynamically and are formed mostly of the same (disc) material. [Abridged], Comment: 23 pages, 34 figures. Accepted for publication in MNRAS. A version with full resolution figures is available at http://www-astro.physics.ox.ac.uk/~bureau/pub_list.html

(Abridged) We present observations of the stellar and gas kinematics for a representative sample of 24 Sa galaxies obtained with our custom-built integral-field spectrograph SAURON operating on the William Herschel Telescope. Our maps typically cover the bulge dominated region. We find a significant fraction of kinematically decoupled components (12/24), many of them displaying central velocity dispersion minima. They are mostly aligned and co-rotating with the main body of the galaxies, and are usually associated with dust discs and rings detected in unsharp-masked images. Almost all the galaxies in the sample (22/24) contain significant amounts of ionised gas which, in general, is accompanied by the presence of dust. The kinematics of the ionised gas is consistent with circular rotation in a disc co-rotating with respect to the stars. The distribution of mean misalignments between the stellar and gaseous angular momenta in the sample suggest that the gas has an internal origin. The [OIII]/Hbeta ratio is usually very low, indicative of current star formation, and shows various morphologies (ring-like structures, alignments with dust lanes or amorphous shapes). The star formation rates in the sample are comparable with that of normal disc galaxies. Low gas velocity dispersion values appear to be linked to regions of intense star formation activity. We interpret this result as stars being formed from dynamically cold gas in those regions. In the case of NGC5953, the data suggest that we are witnessing the formation of a kinematically decoupled component from cold gas being acquired during the ongoing interaction with NGC5954., Comment: 38 pages, 29 figures. Accepted for publication in MNRAS. A version with full resolution figures is available at http://www.strw.leidenuniv.nl/sauron/papers/falcon-barroso2006_sauron7.pdf

We present results from our ongoing effort to understand the nature and evolution of nearby galaxies using the SAURON integral-field spectrograph. In this proceeding we focus on the study of the particular case formed by the interacting galaxies NGC5953 and NGC5954. We present stellar and gas kinematics of the central regions of NGC5953. We use a simple procedure to determine the age of the stellar populations in the central regions and argue that we may be witnessing the formation of a kinematically decoupled component from cold gas being acquired during the ongoing interaction with NGC5954., Comment: 5 pages, 3 figures, to appear in "Science Perspectives for 3D Spectroscopy", eds. M. Kissler-Patig, M. M. Roth and J. R. Walsh, ESO Astrophysics Symposia

We present results from a series of follow-up observations of a sub-sample of the representative SAURON survey elliptical (E) and lenticular (S0) galaxies using the OASIS integral-field spectrograph. These observations focus on the central 10" x 10", with roughly double the spatial resolution of the SAURON observations. This increased spatial resolution reveals a number of interesting and previously unresolved features in the measured stellar kinematics and absorption-line strengths. We find that galaxies exhibiting the youngest global stellar populations (as measured with SAURON) often contain a distinctly young central region (on scales of a few hundred parsec or less) compared to the rest of the galaxy. Moreover, these compact, young components are found to be mostly counter-rotating with respect to the rest of the galaxy. Given that there is no well-established reason for such young components to `prefer' counter- over co-rotation, this finding raises the following questions: How common are these small KDCs as a function of age? Why are there more young than old compact KDCs? Where are the equivalent co-rotating components? We explore these questions using simple simulated velocity fields and stellar population models, and find that the fading of the young component as it evolves, coupled with the fact that counter-rotating components are more easily detected in the velocity field, may help explain the observed trends., Comment: 5 pages, 4 figures, to appear in "Science Perspectives for 3D Spectroscopy", eds. M. Kissler-Patig, M. M. Roth and J. R. Walsh, ESO Astrophysics Symposia. A version with full resolution figures is available at http://www.strw.leidenuniv.nl/~mcdermid/mcdermid_euro3d_eso_20060214.pdf

We present absorption line strength maps of 48 representative elliptical and lenticular galaxies obtained as part of the SAURON survey of nearby galaxies. Using high-quality spectra, spatially binned to a constant signal-to-noise, we measure four key age, metallicity and abundance ratio sensitive indices from the Lick/IDS system over a two-dimensional field extending up to approximately one effective radius. We modify the classical Fe5270 index to define a new index, Fe5270S, which maximizes the usable spatial coverage of SAURON. Maps of Hbeta, Fe5015, Mgb and Fe5270S are presented for each galaxy. We use the maps to compute average line strengths integrated over circular apertures of one-eighth effective radius, and compare the resulting relations of index versus velocity dispersion with previous long-slit work. The metal line strength maps show generally negative gradients with increasing radius roughly consistent with the morphology of the light profiles. Remarkable deviations from this general trend exist, particularly the Mgb isoindex contours appear to be flatter than the isophotes of the surface brightness for about 40% of our galaxies without significant dust features. Generally these galaxies exhibit significant rotation. We infer from this that the fast-rotating component features a higher metallicity and/or an increased Mg/Fe ratio as compared to the galaxy as a whole. The Hbeta maps are typically flat or show a mild positive outwards radial gradient, while a few galaxies show strong central peaks and/or elevated overall Hbeta-strength likely connected to recent star-formation activity. For the most prominent post-starburst galaxies even the metal line strength maps show a reversed gradient. (abridged), Comment: 33 pages, 28 figures. Accepted for publication in MNRAS. A version with full resolution figures is available at http://www.strw.leidenuniv.nl/sauron/papers/kuntschner2006_sauron6.pdf

We present selected results from integral-field spectroscopy of 48 early-type galaxies observed as part of the SAURON survey. Maps of the Hbeta, Fe5015, Mgb and Fe5270 indices in the Lick/IDS system were derived for each of the survey galaxies. The metal line strength maps show generally negative gradients with increasing radius roughly consistent with the morphology of the light profiles. Remarkable deviations from this general trend exist, particularly the Mgb isoindex contours appear to be flatter than the isophotes of the surface brightness for about 40% of our galaxies without significant dust features. Generally these galaxies exhibit significant rotation. We infer from this that the fast-rotating component features a higher metallicity and/or an increased Mg/Fe ratio as compared to the galaxy as a whole. We also use the line strengths maps to compute average values integrated over circular apertures of one effective radius, and derive luminosity weighted ages and metallicities. The lenticular galaxies show a wide range in age and metallicity estimates, while elliptical galaxies tend to occupy regions of older stellar populations., Comment: 5 pages, 4 figures, to appear in "Science Perspectives for 3D Spectroscopy", eds. M. Kissler-Patig, M. M. Roth and J. R. Walsh, ESO Astrophysics Symposia

We have identified two new galaxies with gas counter-rotation (NGC1596 and NGC3203) and have confirmed similar behaviour in another one (NGC128), this using results from separate studies of the ionized-gas and stellar kinematics of a well-defined sample of 30 edge-on disc galaxies. Gas counter-rotators thus represent 10+/-5% of our sample, but the fraction climbs to 21+/-11% when only lenticular (S0) galaxies are considered and to 27+/-13% for S0s with detected ionized-gas only. Those fractions are consistent with but slightly higher than previous studies. A compilation from well-defined studies of S0s in the literature yields fractions of 15+/-4% and 23+/-5%, respectively. Although mainly based on circumstantial evidence, we argue that the counter-rotating gas originates primarily from minor mergers and tidally-induced transfer of material from nearby objects. Assuming isotropic accretion, twice those fractions of objects must have undergone similar processes, underlining the importance of (minor) accretion for galaxy evolution. Applications of gas counter-rotators to barred galaxy dynamics are also discussed., Comment: 8 pages, including 1 table and 2 figures. Accepted for publication in MNRAS. Version with full resolution figures available at http://www-astro.physics.ox.ac.uk/~bureau/pub_list.html

We present results from our ongoing effort to understand the morphological and kinematical properties of early-type galaxies using the integral-field spectrograph SAURON. We discuss the relation between the stellar and gas morphology and kinematics in our sub-sample of 24 representative Sa spiral bulges. We focus on the frequency of kinematically decoupled components and on the presence of star formation in circumnuclear rings., Comment: 6 pages, 3 figures; To appear in the proceedings of the "Island Universes: Structure and Evolution of Disk Galaxies" conference held in Terschelling, Netherlands, July 2005, ed. R. de Jong. A high resolution version is available at http://www.strw.leidenuniv.nl/~jfalcon/JFB_terschelling.pdf.gz

We investigate the well-known correlations between the dynamical mass-to-light ratio M/L and other global observables of elliptical (E) and lenticular (S0) galaxies. We construct two-integral Jeans and three-integral Schwarzschild dynamical models for a sample of 25 E/S0 galaxies with SAURON integral-field stellar kinematics to about one effective (half-light) radius R_e. The comparison of the dynamical M/L with the (M/L)_pop inferred from the analysis of the stellar population, indicates that dark matter in early-type galaxies contributes ~30% of the total mass inside one R_e, in agreement with previous studies, with significant variations from galaxy to galaxy. Our results suggest a variation in M/L at constant (M/L)_pop, which seems to be linked to the galaxy dynamics. We speculate that fast rotating galaxies have lower dark matter fractions than the slow rotating and generally more massive ones., Comment: 4 pages, 3 figures, LaTeX. Proceedings of the XXIst IAP Colloquium "Mass Profiles and Shapes of Cosmological Structures", Editors: G. Mamon, F. Combes, C. Deffayet, B. Fort, EDP Sciences, in press