Publications by Michele Cappellari


Discovery of a giant HI tail in the galaxy group HCG 44

Monthly Notices of the Royal Astronomical Society 428 (2013) 370-380

P Serra, B Koribalski, PA Duc, T Oosterloo, RM McDermid, L Michel-Dansac, E Emsellem, JC Cuillandre, K Alatalo, L Blitz, M Bois, F Bournaud, M Bureau, M Cappellari, AF Crocker, RL Davies, TA Davis, PT Zeeuw, S Khochfar, D Krajnović, H Kuntschner, PY Lablanche, R Morganti, T Naab, M Sarzi, N Scott, AM Weijmans, LM Young

We report the discovery of a giant HI tail in the intragroup medium of HCG 44 as part of the ATLAS3D survey. The tail is ~300 kpc long in projection and contains ~5 × 108 M ⊙of HI. We detect no diffuse stellar light at the location of the tail down to ~28.5 mag arcsec-2 in g band. We speculate that the tail might have formed as gas was stripped from the outer regions of NGC 3187 (a member of HCG 44) by the group tidal field. In this case, a simple model indicates that about 1/3 of the galaxy's HI was stripped during a time interval of <1 Gyr. Alternatively, the tail may be the remnant of an interaction between HCG 44 and NGC 3162, a spiral galaxy now ~650 kpc away from the group. Regardless of the precise formation mechanism, the detected HI tail shows for the first time direct evidence of gas stripping in HCG 44. It also highlights that deep HI observations over a large field are needed to gather a complete census of this kind of events inthe local Universe.©2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


The ATLAS<sup>3D</sup> project - XVIII. CARMA CO imaging survey of early-type galaxies

Monthly Notices of the Royal Astronomical Society 432 (2013) 1796-1844

K Alatalo, TA Davis, M Bureau, LM Young, L Blitz, AF Crocker, E Bayet, M Bois, F Bournaud, M Cappellari, RL Davies, PT De Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnović, H Kuntschner, PY Lablanche, R Morganti, RM McDermid, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, AM Weijmans

We present the Combined Array for Research in Millimeter Astronomy (CARMA) ATLAS3D molecular gas imaging survey, a systematic study of the distribution and kinematics of molecular gas in CO-rich early-type galaxies. Our full sample of 40 galaxies (30 newly mapped and 10 taken from the literature) is complete to a 12CO(1-0) integrated flux of 18.5 Jy km s-1,1 and it represents the largest, best studied sample of its type to date. A comparison of the CO distribution of each galaxy to the g - r colour image (representing dust) shows that the molecular gas and dust distributions are in good agreement and trace the same underlying interstellar medium. The galaxies exhibit a variety of CO morphologies, including discs (50 per cent), rings (15 per cent), bars+rings (10 per cent), spiral arms (5 per cent) and mildly (12.5 per cent) and strongly (7.5 per cent) disrupted morphologies. There appear to be weak trends between galaxy mass and CO morphology, whereby the most massive galaxies in the sample tend to have molecular gas in a disc morphology. We derive a lower limit to the total accreted molecular gas mass across the sample of 2.48 × 1010Mȯ, or approximately 8.3 × 108Mȯ per minor merger within the sample, consistent with minor merger stellar mass ratios. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


The ATLAS<sup>3D</sup> project - XVI. Physical parameters and spectral line energy distributions of the molecular gas in gas-rich early-type galaxies

Monthly Notices of the Royal Astronomical Society 432 (2013) 1742-1767

E Bayet, M Bureau, TA Davis, LM Young, AF Crocker, K Alatalo, L Blitz, M Bois, F Bournaud, M Cappellari, RL Davies, PT de Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnović, H Kuntschner, RM McDermid, R Morganti, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, AM Weijmans

We present a detailed study of the physical properties of the molecular gas in a sample of 18 molecular gas-rich early-type galaxies (ETGs) from the ATLAS3D sample. Our goal is to better understand the star formation processes occurring in those galaxies, starting here with the dense star-forming gas. We use existing integrated 12CO (1-0, 2-1), 13CO (1-0, 2-1), HCN (1-0) and HCO+ (1-0) observations and new 12 CO (3-2) single-dish data. From these, we derive for the first time the average kinetic temperature, H2 volume density and column density of the emitting gas in a significant sample of ETGs, using a non-local thermodynamical equilibrium theoretical model. Since the CO lines trace different physical conditions than of those the HCN and HCO+ lines, the two sets of lines are treated separately. For most of the molecular gas-rich ETGs studied here, the CO transitions can be reproduced with kinetic temperatures of 10-20 K, H2 volume densities of 103-4 cm-3 and CO column densities of 1018-20 cm-2. The physical conditions corresponding to the HCN and HCO+ gas component have large uncertainties and must be considered as indicative only. We also compare for the first time the predicted CO spectral line energy distributions and gas properties of our molecular gas-rich ETGs with those of a sample of nearby well-studied disc galaxies. The gas excitation conditions in 13 of our 18 ETGs appear analogous to those in the centre of theMilky Way, hence the star formation activity driving these conditions is likely of a similar strength and nature. Such results have never been obtained before for ETGs and open a new window to explore further star-formation processes in the Universe. The conclusions drawn should nevertheless be considered carefully, as they are based on a limited number of observations and on a simple model. In the near future, with higher CO transition observations, it should be possible to better identify the various gas components present in ETGs, as well as more precisely determine their associated physical conditions. To achieve these goals, we show here from our theoretical study, that mid-J CO lines [such as the 12CO (6-5) line] are particularly useful. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


The atlas3d project - xiv. the extent and kinematics of the molecular gas in early-type galaxies

Monthly Notices of the Royal Astronomical Society 429 (2013) 534-555

TA Davis, K Alatalo, M Bureau, M Cappellari, N Scott, LM Young, L Blitz, A Crocker, E Bayet, M Bois, F Bournaud, RL Davies, PT De Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnovíc, H Kuntschner, PY Lablanche, RM McDermid, R Morganti, T Naab, T Oosterloo, M Sarzi, P Serra, AM Weijmans

We use interferometric 12CO(1-0) observations to compare and contrast the extent, surface brightness profiles and kinematics of the molecular gas in CO-rich ATLAS3D early-type galaxies (ETGs) and spiral galaxies. We find that the molecular gas extent is smaller in absolute terms in ETGs than in late-type galaxies, but that the size distributions are similar once scaled by the galaxies optical/stellar characteristic scalelengths. Amongst ETGs, we find that the extent of the gas is independent of its kinematic misalignment (with respect to the stars), but does depend on the environment, with Virgo cluster ETGs having less extended molecular gas reservoirs, further emphasizing that cluster ETGs follow different evolutionary pathways from those in the field. Approximately half of ETGs have molecular gas surface brightness profiles that follow the stellar light profile. These systems often have relaxed gas out to large radii, suggesting they are unlikely to have had recent merger/accretion events. A third of the sample galaxies show molecular gas surface brightness profiles that fall off slower than the light, and sometimes show a truncation. These galaxies often have a low mass, and eitherhave disturbed molecular gas or are in the Virgo cluster, suggesting that recent mergers, ram pressure stripping and/or the presence of hot gas can compress/truncate the gas. The remaining galaxies have rings, or composite profiles, that we argue can be caused by the effects of bars. We investigated the kinematics of the molecular gas using position-velocity diagrams, and compared the observed kinematics with dynamical model predictions, and the observed stellar and ionized gas velocities. We confirm that the molecular gas reaches beyond the turnover of the circular velocity curve in~70 per cent of our CO-rich ATLAS3D ETGs, validating previous work on the CO Tully-Fisher relation. In general we find that in most galaxies the molecular gas is dynamically cold, and the observed CO rotation matches well model predictions of the circular velocity. In the galaxies with the largest molecular masses, dust obscuration and/or population gradients can cause model predictions of the circular velocity to disagree with observations of the molecular gas rotation; however, these effects are confined to the most star forming systems. Bars and non-equilibrium conditions can also make the gas deviate from circular orbits. In both these cases, one expects the model circular velocity to be higher than the observed CO velocity, in agreement with our observations. Molecular gas is a better direct tracer of the circular velocity than the ionized gas, justifying its use as a kinematic tracer for Tully-Fisher and similar analyses.


A black-hole mass measurement from molecular gas kinematics in NGC4526

Nature 494 (2013) 328-330

TA Davis, M Bureau, M Cappellari, M Sarzi, L Blitz

The masses of the supermassive black holes found in galaxy bulges are correlated with a multitude of galaxy properties, leading to suggestions that galaxies and black holes may evolve together. The number of reliably measured black-hole masses is small, and the number of methods for measuring them is limited, holding back attempts to understand this co-evolution. Directly measuring black-hole masses is currently possible with stellar kinematics (in early-type galaxies), ionized-gas kinematics (in some spiral and early-type galaxies) and in rare objects that have central maser emission. Here we report that by modelling the effect of a black hole on the kinematics of molecular gas it is possible to fit interferometric observations of CO emission and thereby accurately estimate black-hole masses. We study the dynamics of the gas in the early-type galaxy NGC 4526, and obtain a best fit that requires the presence of a central dark object of× 10 8 solar masses (3σ confidence limit). With the next-generation millimetre-wavelength interferometers these observations could be reproduced in galaxies out to 75 megaparsecs in less than 5 hours of observing time. The use of molecular gas as a kinematic tracer should thus allow one to estimate black-hole masses in hundreds of galaxies in the local Universe, many more than are accessible with current techniques. © 2013 Macmillan Publishers Limited. All rights reserved.


Disentangling the stellar populations in the counter-rotating disc galaxy NGC 4550

Monthly Notices of the Royal Astronomical Society 428 (2013) 1296-1302

EJ Johnston, MR Merrifield, A Araǵon-Salamanca, M Cappellari

In order to try and understand its origins, we present high-quality long-slit spectral observations of the counter-rotating stellar discs in the strange S0 galaxy NGC 4550. We kinematically decompose the spectra into two counter-rotating stellar components (plus a gaseous component), in order to study both their kinematics and their populations. The derived kinematics largely confirm what was known previously about the stellar discs, but trace them to larger radii with smaller errors; the fitted gaseous component allows us to trace the hydrogen emission lines for the first time, which are found to follow the same rather strange kinematics previously seen in the [OIII] line. Analysis of the populations of the two separate stellar components shows that the secondary disc has a significantly younger mean age than the primary disc, consistent with later star formation from the associated gaseous material. In addition, the secondary disc is somewhat brighter, also consistent with such additional star formation. However, these measurements cannot be self-consistently modelled by a scenario in which extra stars have been added to initially identical counter-rotating stellar discs, which rules out the Evans & Collett's elegant 'separatrix-crossing' model for the formation of such massive counter-rotating discs from a single galaxy, leaving some form of unusual gas accretion history as the most likely formation mechanism. © 2012 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


Simulations of Binary Galaxy Mergers and the Link with Fast Rotators, Slow Rotators, and Kinematically Distinct Cores

GALAXY MERGERS IN AN EVOLVING UNIVERSE 477 (2013) 97-+

M Bois, E Emsellem, F Bournaud, K Alatalo, L Blitz, M Bureau, M Cappellari, RL Davies, TA Davis, PT de Zeeuw, P-A Duc, S Khochfar, D Krajnovic, H Kuntschner, P-Y Lablanche, RM McDermid, R Morganti, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, A-M Weijmans, LM Young


The ATLAS<sup>3D</sup> project - XIX. The hot gas content of early-type galaxies: Fast versus slow rotators

Monthly Notices of the Royal Astronomical Society 432 (2013) 1845-1861

M Sarzi, K Alatalo, L Blitz, M Bois, F Bournaud, M Bureau, M Cappellari, A Crocker, RL Davies, TA Davis, PT de Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnović, H Kuntschner, PY Lablanche, RM McDermid, R Morganti, T Naab, T Oosterloo, N Scott, P Serra, LM Young, AM Weijmans

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. A halo of hot gas may act as an effective shield against the acquisition of cold gas and can quickly absorb stellar mass loss material. Yet, since the discovery by the Einstein Observatory of such X-ray haloes around early-type galaxies, the precise amount of hot gas around these galaxies still remains a matter of debate. By combining homogeneously derived photometric and spectroscopic measurements for the early-type galaxies observed as part of the ATLAS3D integral field survey with measurements of their X-ray luminosity based on X-ray data of both low and high spatial resolution (for 47 and 19 objects, respectively) 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 haloes with luminosity LX, gas and temperature T values that are well in line with what is expected if the hot gas emission is sustained by the thermalization of the kinetic energy carried by the stellar mass loss material, fast rotators tend to display LX, gas values that fall consistently below the prediction of thismodel, with similar T values that do not scale with the stellar kinetic energy (traced by the stellar velocity dispersion) as observed in the case of slow rotators. Such a discrepancy between the hot gas content of slow and fast rotators would appear to reduce, or even disappear, for large values of the dynamical mass (above ∼3× 1011Mȯ), with younger fast rotators displaying also somewhat larger LX, gas values possibly owing to the additional energy input from recent supernovae explosions. Considering that fast rotators are likely to be intrinsically flatter than slow rotators, and that the few LX, gas-deficient slow rotators also happen to be relatively flat, the observed LX, gas deficiency in these objects would support the hypothesis whereby flatter galaxies have a harder time in retaining their hot gas, although we suggest that the degree of rotational support could further hamper the efficiency with which the kinetic energy of the stellar mass loss material is thermalized in the 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 LX, gas deficiency of fast rotators would make them more capable to recycle the stellar mass loss material into new stars than slow rotators. This would be consistent with the finding that molecular gas and young stellar populations are detected only in fast rotators across the entire ATLAS3D sample, and that fast rotators tend to have a larger specific dust mass content than slow rotators. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


The planetary nebulae population in the nuclear regions of M31: the SAURON view

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 430 (2013) 1219-1229

N Pastorello, M Sarzi, M Cappellari, E Emsellem, GA Mamon, R Bacon, RL Davies, PT de Zeeuw


The ATLAS<sup>3D</sup> project-XX. Mass-size and mass-σ distributions of early-type galaxies: Bulge fraction drives kinematics, mass-to-light ratio, molecular gas fraction and stellar initial mass function

Monthly Notices of the Royal Astronomical Society 432 (2013) 1862-1893

M Cappellari, RM McDermid, K Alatalo, L Blitz, M Bois, F Bournaud, M Bureau, AF Crocker, RL Davies, TA Davis, PT de Zeeuw, PA Duc, E Emsellem, S Khochfar, D Krajnović, H Kuntschner, R Morganti, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, AM Weijmans, LM Young

In the companion Paper XV of this series, we derive accurate total mass-to-light ratios (M/L)JAM ≈ (M/L)(r = Re) within a sphere of radius r = Re centred on the galaxy, as well as stellar (M/L)stars (with the dark matter removed) for the volume-limited and nearly massselected (stellarmassM* ≲ 6 × 109M⊙)ATLAS3D sample of 260 early-type galaxies (ETGs, ellipticals Es and lenticulars S0s). Here, we use those parameters to study the two orthogonal projections (MJAM, σe) and (MJAM,R maje ) of the thin Mass Plane (MP) (MJAM, σe,Rmaje ) which describes the distribution of the galaxy population, where MJAM = L × (M/L)JAM ≈ M*. The distribution of galaxy properties on both projections of the MP is characterized by: (i) the same zone of exclusion (ZOE), which can be transformed from one projection to the other using the scalar virial equation. The ZOE is roughly described by two power laws, joined by a break at a characteristic mass MJAM ≈ 3 × 1010M⊙, which corresponds to the minimum Re and maximum stellar density. This results in a break in the meanMJAM-σe relation with trends MJAM α σ2.3e and MJAM α σ4.7e at small and large σe, respectively; (ii) a characteristic mass MJAM ≈ 2 × 1011M⊙ which separates a population dominated by flat fast rotator with discs 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 on the two projections of the MP tends to be constant along lines of roughly constant se, or equivalently along lines with Rmaje α MJAM, respectively (or even better parallel to the ZOE: Rmaje α M0.75JAM); (iv) it forms a continuous and 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 use dynamical models to analyse our kinematic maps. We show that σe traces the bulge fraction, which appears to be the main driver for the observed trends in the dynamical (M/L)JAM and in indicators of the (M/L)pop of the stellar population like Hβ and colour, as well as in the molecular gas fraction. A similar variation along contours of σe is also observed for the mass normalization of the stellar initial mass function (IMF), which was recently shown to vary systematically within the ETGs' population. Our preferred relation has the form log10[(M/L)stars/(M/L)Salp] = a + b × log10(σe/130 km s-1) with a=-0.12 ± 0.01 and b = 0.35 ± 0.06. Unless there are major flaws in all stellar population models, this trend implies a transition of the mean IMF from Kroupa to Salpeter in the interval log10(σe/km s-1) ≈ 1.9-2.5 (or σe ≈ 90-290 km s-1), with a smooth variation in between, consistently with what was shown in Cappellari et al. The observed distribution of galaxy properties on the MP provides a clean and novel view for a number of previously reported trends, which constitute special two-dimensional projections of the more general four-dimensional parameters trends on the MP. We interpret it as due to a combination of two main effects: (i) an increase of the bulge fraction, which increases σe, decreases Re, and greatly enhance the likelihood for a galaxy to have its star formation quenched, and (ii) dry merging, increasing galaxy mass and Re by moving galaxies along lines of roughly constant σe (or steeper), while leaving the population nearly unchanged. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.


A black-hole mass measurement from molecular gas kinematics in NGC4526

Nature (2013)

TA Davis, M Bureau, M Cappellari, M Sarzi, L Blitz


AGN feedback driven molecular outflow in NGC 1266

Proceedings of the International Astronomical Union 8 (2012) 175-176

K Alatalo, KE Nyland, G Graves, S Deustua, J Wrobel, LM Young, TA Davis, M Bureau, E Bayet, L Blitz, M Bois, F Bournaud, M Cappellari, RL Davies, PT De Zeeuw, E Emsellem, S Khochfar, D Krajnovic, H Kuntschner, S Martín, RM Mcdermid, R Morganti, T Naab, M Sarzi, N Scott, P Serra, A Weijmans

NGC 1266 is a nearby field galaxy observed as part of the ATLAS 3D 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 brightness 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. © International Astronomical Union 2013.


Revealing the origin of the cold ISM in massive early-type galaxies

Proceedings of the International Astronomical Union 8 (2012) 324-327

TA Davis, K Alatalo, M Bureau, L Young, L Blitz, A Crocker, E Bayet, M Bois, F Bournaud, M Cappellari, RL Davies, PA Duc, PT De Zeeuw, E Emsellem, J Falcon-Barroso, S Khochfar, D Krajnovic, H Kuntschner, PY Lablanche, RM McDermid, R Morganti, T Naab, M Sarzi, N Scott, P Serra, A Weijmans

Recently, massive early-type galaxies have shed their red-and-dead moniker, thanks to the discovery that many host residual star formation. As part of the ATLAS-3D project, we have conducted a complete, volume-limited survey of the molecular gas in 260 local early-type galaxies with the IRAM-30m telescope and the CARMA interferometer, in an attempt to understand the fuel powering this star formation. We find that around 22% of early-type galaxies in the local volume host molecular gas reservoirs. This detection rate is independent of galaxy luminosity and environment. Here we focus on how kinematic misalignment measurements and gas-to-dust ratios can be used to put constraints on the origin of the cold ISM in these systems. The origin of the cold ISM seems to depend strongly on environment, with misaligned, dust poor gas (indicative of externally acquired material) being common in the field but completely absent in rich groups and in the Virgo cluster. Very massive galaxies also appear to be devoid of accreted gas. This suggests that in the field mergers and/or cold gas accretion dominate the gas supply, while in clusters internal secular processes become more important. This implies that environment has a strong impact on the cold gas properties of ETGs. © 2013 International Astronomical Union.


Parallel-sequencing of early-type and spiral galaxies

Proceedings of the International Astronomical Union Cambridge University Press 10 (2012) 330-

M Cappellari

Since Edwin Hubble introduced his famous tuning fork diagram more than 70 years ago, spiral galaxies and early-type galaxies (ETGs) have been regarded as two distinct families. The spirals are characterized by the presence of disks of stars and gas in rapid rotation, while the early-types are gas poor and described as spheroidal systems, with less rotation and often non-axisymmetric shapes. The separation is physically relevant as it implies a distinct path of formation for the two classes of objects. I will give an overview of recent findings, from independent teams, that motivated a radical revision to Hubble's classic view of ETGs. These results imply a much closer link between spiral galaxies and ETGs than generally assumed.


Gemini GMOS and WHT SAURON integral-field spectrograph observations of the AGN-driven outflow in NGC1266

Monthly Notices of the Royal Astronomical Society 426 (2012) 1574-1590

TA Davis, D Krajnović, RM McDermid, M Bureau, M Sarzi, K Nyland, K Alatalo, E Bayet, L Blitz, M Bois, F Bournaud, M Cappellari, A Crocker, RL Davies, PT de Zeeuw, PA Duc, E Emsellem, S Khochfar, H Kuntschner, PY Lablanche, R Morganti, T Naab, T Oosterloo, N Scott, P Serra, AM Weijmans, LM Young

We use the Spectrographic Areal Unit for Research on Optical Nebulae and Gemini Multi-Object Spectrograph integral-field spectrographs to observe the active galactic nucleus (AGN) powered outflow in NGC1266. This unusual galaxy is relatively nearby (D = 30Mpc), allowing us to investigate the process of AGN feedback in action. We present maps of the kinematics and line strengths of the ionized gas emission lines Hα, Hβ, [Oiii], [Oi], [Nii] and [Sii], and report on the detection of sodium D absorption. We use these tracers to explore the structure of the source, derive the ionized and atomic gas kinematics, and investigate the gas excitation and physical conditions. NGC1266 contains two ionized gas components along most lines of sight, tracing the ongoing outflow and a component closer to the galaxy systemic, the origin of which is unclear. This gas appears to be disturbed by a nascent AGN jet. We confirm that the outflow in NGC1266 is truly multiphase, containing radio plasma, atomic, molecular and ionized gas and X-ray emitting plasma. The outflow has velocities of up to ±900 km s -1 away from the systemic velocity and is very likely to remove significant amount of cold gas from the galaxy. The low-ionization nuclear emission region-like line emission in NGC1266 is extended, and it likely arises from fast shocks caused by the interaction of the radio jet with the interstellar medium. These shocks have velocities of up to 800 km s -1, which match well with the observed velocity of the outflow. Sodium D equivalent width profiles are used to set constraints on the size and orientation of the outflow. The ionized gas morphology correlates with the nascent radio jets observed in 1.4 and 5 GHz continuum emission, supporting the suggestion that an AGN jet is providing the energy required to drive the outflow. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


An oxford swift integral field spectroscopy study of 14 early-type galaxies in the coma cluster

Monthly Notices of the Royal Astronomical Society 425 (2012) 1521-1526

N Scott, R Houghton, RL Davies, M Cappellari, N Thatte, F Clarke, M Tecza

As a demonstration of the capabilities of the new Oxford SWIFT integral field spectrograph, we present first observations for a set of 14 early-type galaxies in the core of the Coma cluster. Our data consist of I- and z-band spatially resolved spectroscopy obtained with the Oxford SWIFT spectrograph, combined with r-band photometry from the Sloan Digital Sky Survey archive for 14 early-type galaxies. We derive spatially resolved kinematics for all objects from observations of the calcium triplet absorption features at ∼8500Å. Using this kinematic information we classify galaxies as either fast rotators or slow rotators. We compare the fraction of fast and slow rotators in our sample, representing the densest environment in the nearby Universe, to results from the ATLAS 3D survey, finding that the slow rotator fraction is ∼50per cent larger in the core of the Coma cluster than in the volume-limited ATLAS 3D sample, a 1.2σ increase given our selection criteria. Comparing our sample to the Virgo cluster core only (which is 24 times less dense than the Coma core) we find no evidence of an increase in the slow rotator fraction. Combining measurements of the effective velocity dispersion σ e with the photometric data we determine the Fundamental Plane for our sample of galaxies. We find that the use of the average velocity dispersion within 1 effective radius, σ e, reduces the residuals by 13per cent with respect to comparable studies using central velocity dispersions, consistent with other recent integral field Fundamental Plane determinations. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


The ATLAS project - XII. Recovery of the mass-to-light ratio of simulated early-type barred galaxies with axisymmetric dynamical models

Monthly Notices of the Royal Astronomical Society 424 (2012) 1495-1521

PY Lablanche, M Cappellari, E Emsellem, F Bournaud, L Michel-Dansac, K Alatalo, L Blitz, M Bois, M Bureau, RL Davies, TA Davis, PT de Zeeuw, PA Duc, S Khochfar, D Krajnović, H Kuntschner, R Morganti, RM McDermid, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, AM Weijmans, LM Young

We investigate the accuracy in the recovery of the stellar dynamics of barred galaxies when using axisymmetric dynamical models. We do this by trying to recover the mass-to-light ratio (M/L) and the anisotropy of realistic galaxy simulations using the Jeans Anisotropic Multi-Gaussian Expansion (JAM) modelling method. However, given that the biases we find are mostly due to an application of an axisymmetric modelling algorithm to a non-axisymmetric system and in particular to inaccuracies in the deprojected mass model, our results are relevant for general axisymmetric modelling methods. We run N-body collisionless simulations to build a library with various luminosity distribution, constructed to mimic real individual galaxies, with realistic anisotropy. The final result of our evolved library of simulations contains both barred and unbarred galaxies. The JAM method assumes an axisymmetric mass distribution, and we adopt a spatially constant M/L and anisotropy distributions. The models are fitted to two-dimensional maps of the second velocity moments of the simulations for various viewing angles [position angle (PA) of the bar and inclination of the galaxy]. We find that the inclination is generally well recovered by the JAM models, for both barred and unbarred simulations. For unbarred simulations the M/L is also accurately recovered, with negligible median bias and with a maximum one of just Δ(M/L) < 1.5 per cent when the galaxy is not too close to face on. At very low inclinations the M/L can be significantly overestimated (9 per cent in our tests, but errors can be larger for very face-on views). This is in agreement with previous studies. For barred simulations the M/L is on average (when PA = 45°) essentially unbiased, but we measure an over/underestimation of up to Δ(M/L) = 15 per cent in our tests. The sign of the M/L bias depends on the PA of the bar as expected: overestimation occurs when the bar is closer to end-on, due to the increased stellar motion along the line-of-sight, and underestimation otherwise. For unbarred simulations, the JAM models are able to recover the mean value of the anisotropy with bias, within the region constrained by the kinematics. However when a bar is present, or for nearly face-on models, the recovered anisotropy varies wildly, with biases up to Δβ z≈ 0.3. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.


Deep near-infrared spectroscopy of passively evolving galaxies at z≳1.4

Astrophysical Journal 755 (2012)

M Onodera, A Renzini, M Carollo, M Cappellari, C Mancini, V Strazzullo, E Daddi, N Arimoto, R Gobat, Y Yamada, HJ McCracken, O Ilbert, P Capak, A Cimatti, M Giavalisco, AM Koekemoer, X Kong, S Lilly, K Motohara, K Ohta, DB Sanders, N Scoville, N Tamura, Y Taniguchi

We present the results of new near-IR spectroscopic observations of passive galaxies at z ≳ 1.4 in a concentration of BzK-selected galaxies in the COSMOS field. The observations have been conducted with Subaru/MOIRCS, and have resulted in absorption lines and/or continuum detection for 18 out of 34 objects. This allows us to measure spectroscopic redshifts for a sample that is almost complete to K AB = 21. COSMOS photometric redshifts are found in fair agreement overall with the spectroscopic redshifts, with a standard deviation of 0.05; however, 30% of objects have photometric redshifts systematically underestimated by up to 25%. We show that these systematic offsets in photometric redshifts can be removed by using these objects as a training set. All galaxies fall in four distinct redshift spikes at z = 1.43, 1.53, 1.67, and 1.82, with this latter one including seven galaxies. SED fits to broadband fluxes indicate stellar masses in the range of 4-40 × 10 10 M and that star formation was quenched 1Gyr before the cosmic epoch at which they are observed. The spectra of several individual galaxies have allowed us to measure their HδF indices and the strengths of the 4000 Å break, which confirms their identification as passive galaxies, as does a composite spectrum resulting from the co-addition of 17 individual spectra. The effective radii of the galaxies have been measured on the COSMOS HST/ACS i F814W-band image, confirming the coexistence at these redshifts of passive galaxies, which are substantially more compact than their local counterparts with others that follow the local effective radius-stellar mass relation. For the galaxy with the best signal-to-noise spectrum we were able to measure a velocity dispersion of 270 ± 105kms-1 (error bar including systematic errors), indicating that this galaxy lies closely on the virial relation given its stellar mass and effective radius. © 2012 The American Astronomical Society. All rights reserved.


DEEP NEAR-INFRARED SPECTROSCOPY OF PASSIVELY EVOLVING GALAXIES AT z greater than or similar to 1.4

ASTROPHYSICAL JOURNAL 755 (2012) ARTN 26

M Onodera, A Renzini, M Carollo, M Cappellari, C Mancini, V Strazzullo, E Daddi, N Arimoto, R Gobat, Y Yamada, HJ McCracken, O Ilbert, P Capak, A Cimatti, M Giavalisco, AM Koekemoer, X Kong, S Lilly, K Motohara, K Ohta, DB Sanders, N Scoville, N Tamura, Y Taniguchi


Quenching of Star Formation in Molecular Outflow Host NGC 1266

Proceedings of the International Astronomical Union Cambridge University Press (CUP) 8 (2012) 371-371

K Alatalo, KE Nyland, G Graves, S Deustua, LM Young, TA Davis, AF Crocker, M Bureau, E Bayet, L Blitz, M Bois, F Bournaud, M Cappellari, RL Davies, PT de Zeeuw, E Emsellem, S Khochfar, D Krajnovic, H Kuntschner, RM McDermid, R Morganti, T Naab, T Oosterloo, M Sarzi, N Scott, P Serra, A Weijmans

<jats:title>Abstract</jats:title><jats:p>We detail the rich molecular story of NGC 1266, its serendipitous discovery within the ATLAS<jats:sup>3D</jats:sup> survey (Cappellari <jats:italic>et al</jats:italic>. 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 <jats:monospace>SAURON</jats:monospace>, 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 <jats:italic>M</jats:italic><jats:sub>⊙</jats:sub> yr<jats:sup>−1</jats:sup>). On the other hand, tracers of <jats:italic>recent</jats:italic> star formation, such as the Hβ absorption map from <jats:monospace>SAURON</jats:monospace> 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 <jats:italic>et al</jats:italic>. 2011).</jats:p>

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