Publications by Martin Bureau


KROSS-SAMI: a direct IFS comparison of the Tully-Fisher relation across 8 Gyr since z approximate to 1

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 482 (2019) 2166-2188

AL Tiley, M Bureau, L Cortese, CM Harrison, HL Johnson, JP Stott, AM Swinbank, I Smail, D Sobral, AJ Bunker, K Glazebrook, RG Bower, D Obreschkow, JJ Bryant, MJ Jarvis, J Bland-Hawthorn, G Magdis, AM Medling, SM Sweet, C Tonini, OJ Turner, RM Sharples, SM Croom, M Goodwin, IS Konstantopoulos, NPF Lorente, JS Lawrence, J Mould, MS Owers, SN Richards


The energetics of starburst-driven outflows at z ∼ 1 from KMOS

Monthly Notices of the Royal Astronomical Society Oxford University Press 487 (2019) 381–393-

AM Swinbank, CM Harrison, AL Tiley, HL Johnson, I Smail, JP Stott, PN Best, M Bureau, RG Bower, A Bunker, M Cirasuolo, GE Magdis, M Jarvis, RM Sharples, D Sobral

We present an analysis of the gas outflow energetics from KMOS observations of ∼ 529 main-sequence star-forming galaxies at z ∼ 1 using broad, underlying H α and forbidden lines of [N II] and [S II]. Based on the stacked spectra for a sample with median star-formation rates and stellar masses of SFR = 7 M⊙   yr−1 and M⋆ = (1.0 ± 0.1) × 1010 M⊙, respectively, we derive a typical mass outflow rate of M˙wind = 1–4 M⊙ yr−1 and a mass loading of M˙wind / SFR = 0.2–0.4. By comparing the kinetic energy in the wind with the energy released by supernovae, we estimate a coupling efficiency between the star formation and wind energetics of ϵ ∼  0.03. The mass loading of the wind does not show a strong trend with star-formation rate over the range ∼ 2–20 M⊙ yr−1, although we identify a trend with stellar mass such that dM / dt / SFR ∝ M0.26±0.07⋆⁠. Finally, the line width of the broad H α increases with disc circular velocity with a sub-linear scaling relation FWHMbroad ∝ v0.21 ± 0.05. As a result of this behaviour, in the lowest mass galaxies (M⋆ ≲ 1010 M⊙), a significant fraction of the outflowing gas should have sufficient velocity to escape the gravitational potential of the halo whilst in the highest mass galaxies (M⋆ ≳ 1010 M⊙) most of the gas will be retained, flowing back on to the galaxy disc at later times.


JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution studies: II. SCUBA-2 850 μm data reduction and dust flux density catalogues

Monthly Notices of the Royal Astronomical Society Oxford University Press 486 (2019) 4166–4185-

MWL Smith, CJR Clark, I De Looze, I Lamperti, A Saintonge, CD Wilson, G Accurso, E Brinks, M Bureau, EJ Chung, PJ Cigan, DL Clements, T Dharmawardena, L Fanciullo, Y Gao, Y Gao, WK Gear, HL Gomez, J Greenslade, HS Hwang, F Kemper, JC Lee, C Li, L Lin, L Liu

We present the SCUBA-2 850μm component of JINGLE, the new JCMT large survey for dust and gas in nearby galaxies, which with 193 galaxies is the largest targeted survey of nearby galaxies at 850 μm. We provide details of our SCUBA-2 data reduction pipeline, optimized for slightly extended sources, and including a calibration model adjusted to match conventions used in other far-infrared (FIR) data. We measure total integrated fluxes for the entire JINGLE sample in 10 infrared/submillimetre bands, including all WISE, Herschel-PACS, Herschel-SPIRE, and SCUBA-2 850 μm maps, statistically accounting for the contamination by CO(J = 3–2) in the 850 μm band. Of our initial sample of 193 galaxies, 191 are detected at 250 μm with a ≥5σ significance. In the SCUBA-2 850 μm band we detect 126 galaxies with ≥3σ significance. The distribution of the JINGLE galaxies in FIR/sub-millimetre colour–colour plots reveals that the sample is not well fit by single modified-blackbody models that assume a single dust-emissivity index (β). Instead, our new 850 μm data suggest either that a large fraction of our objects require β < 1.5, or that a model allowing for an excess of sub-mm emission (e.g. a broken dust emissivity law, or a very cold dust component ≲10 K) is required. We provide relations to convert FIR colours to dust temperature and β for JINGLE-like galaxies. For JINGLE the FIR colours correlate more strongly with star-formation rate surface-density rather than the stellar surface-density, suggesting heating of dust is greater due to younger rather than older stellar-populations, consistent with the low proportion of early-type galaxies in the sample.


Dust properties in the cold and hot gas phases of the ATLAS(3D) early-type galaxies as revealed by AKARI

ASTRONOMY & ASTROPHYSICS 622 (2019) ARTN A87

T Kokusho, H Kaneda, M Bureau, T Suzuki, K Murata, A Kondo, M Yamagishi, T Tsuchikawa, T Furuta


The AGN fuelling/feedback cycle in nearby radio galaxies I. ALMA observations and early results

Monthly Notices of the Royal Astronomical Society Oxford University Press 484 (2019) 4239–4259-

I Ruffa, I Prandoni, R Laing, R Paladino, P Parma, H de Ruiter, A Mignano, TA Davis, M Bureau, J Warren

This is the first 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, warm and cold gas, radio jets) with the aim of improving our understanding of the AGN fuelling/feedback cycle in LERGs. We present ALMA Band 6 12CO(2-1) and continuum observations of nine sources. Continuum emission from the radio cores was detected in all objects. Six sources also show mm emission from jets on kpc/sub-kpc scales. The jet structures are very similar at mm and cm wavelengths. We conclude that synchrotron emission associated with the radio jets dominates the continuum spectra up to 230 GHz. The 12CO(2-1) line was detected in emission in six out of nine objects, with molecular gas masses ranging from 2 × 107 to 2 × 1010 M⊙. The CO detections show disc-like structures on scales from ≈0.2 to ≈10 kpc. In one case (NGC 3100) the CO disc presents some asymmetries and is disrupted in the direction of the northern radio jet, indicating a possible jet/disc interaction. In IC 4296, CO is detected in absorption against the radio core as well as in emission. In four of the six galaxies with CO detections, the gas rotation axes are roughly parallel to the radio jets in projection; the remaining two cases show large misalignments. In those objects where optical imaging is available, dust and CO appear to be co-spatial.


WISDOM project – IV. A molecular gas dynamical measurement of the supermassive black hole mass in NGC 524

Monthly Notices of the Royal Astronomical Society Oxford University Press 485 (2019) 4359–4374-

MD Smith, M Bureau, TA Davis, M Cappellari, L Liu, EV North, K Onishi, S Iguchi, M Sarzi

We present high angular resolution (0.3 arcsec or 37 pc) Atacama Large Millimeter/submillimeter Array observations of the CO(2–1) line emission from a central disc in the early-type galaxy NGC 524. This disc is shown to be dynamically relaxed, exhibiting ordered rotation about a compact 1.3 mm continuum source, which we identify as emission from an active supermassive black hole (SMBH). There is a hole at the centre of the disc slightly larger than the SMBH sphere of influence. An azimuthal distortion of the observed velocity field is found to be due to either a position angle warp or radial gas flow over the inner 2. 5. By forward-modelling the observations, we obtain an estimate of the SMBH mass of 4.0+3.5 −2.0 × 108 M, where the uncertainties are at the 3σ level. The uncertainties are dominated by the poorly constrained inclination and the stellar mass-to-light ratio of this galaxy, and our measurement is consistent with the established correlation between SMBH mass and stellar velocity dispersion. Our result is roughly half that of the previous stellar dynamical measurement, but is consistent within the uncertainties of both. We also present and apply a new tool for modelling complex molecular gas distributions.


The shapes of the rotation curves of star-forming galaxies over the last approximate to 10 Gyr

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 485 (2019) 934-960

AL Tiley, AM Swinbank, CM Harrison, I Smail, OJ Turner, M Schaller, JP Stott, D Sobral, T Theuns, RM Sharples, S Gillman, RG Bower, AJ Bunker, P Best, J Richard, R Bacon, M Bureau, M Cirasuolo, G Magdis


SIGNALS: I. Survey description

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 489 (2019) 5530-5546

L Rousseau-Nepton, RP Martin, C Robert, L Drissen, P Amram, S Prunet, T Martin, I Moumen, A Adamo, A Alarie, P Barmby, A Boselli, F Bresolin, M Bureau, L Chemin, RC Fernandes, F Combes, C Crowder, L Della Bruna, S Duarte Puertas, F Egusa, B Epinat, VF Ksoll, M Girard, V Gómez Llanos, D Gouliermis, K Grasha, C Higgs, J Hlavacek-Larrondo, I-T Ho, J Iglesias-Páramo, G Joncas, ZS Kam, P Karera, RC Kennicutt, RS Klessen, S Lianou, L Liu, Q Liu, AL de Amorim, JD Lyman, H Martel, B Mazzilli-Ciraulo, AF McLeod, A-L Melchior, I Millan, M Mollá, R Momose, C Morisset, H-A Pan, AK Pati, A Pellerin, E Pellegrini, I Pérez, A Petric, H Plana, D Rahner, T Ruiz Lara, L Sánchez-Menguiano, K Spekkens, G Stasińska, M Takamiya, N Vale Asari, JM Vílchez

<jats:title>ABSTRACT</jats:title> <jats:p>SIGNALS, the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey, is a large observing programme designed to investigate massive star formation and H ii regions in a sample of local extended galaxies. The programme will use the imaging Fourier transform spectrograph SITELLE at the Canada–France–Hawaii Telescope. Over 355 h (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 H ii regions: the largest, most complete, and homogeneous data base of spectroscopically and spatially resolved extragalactic H ii 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, and supernova remnants. The purpose of this paper is to present a general outlook of the survey, notably the observing strategy, galaxy sample, and science requirements.</jats:p>


WISDOM project – V. Resolving molecular gas in Keplerian rotation around the supermassive black hole in NGC 0383

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 490 (2019) 319-330

EV North, TA Davis, M Bureau, M Cappellari, S Iguchi, L Liu, K Onishi, M Sarzi, MD Smith, TG Williams

<jats:title>ABSTRACT</jats:title> <jats:p>As part of the mm-Wave Interferometric Survey of Dark Object Masses (WISDOM), we present a measurement of the mass of the supermassive black hole (SMBH) in the nearby early-type galaxy NGC 0383 (radio source 3C 031). This measurement is based on Atacama Large Millimeter/sub-millimeter Array (ALMA) cycle 4 and 5 observations of the 12CO(2–1) emission line with a spatial resolution of 58 × 32 pc2 (0.18 arcsec × 0.1 arcsec). This resolution, combined with a channel width of 10 km s−1, allows us to well resolve the radius of the black hole sphere of influence (measured as RSOI = 316 pc  =  0.98 arcsec), where we detect a clear Keplerian increase of the rotation velocities. NGC 0383 has a kinematically relaxed, smooth nuclear molecular gas disc with weak ring/spiral features. We forward model the ALMA data cube with the Kinematic Molecular Simulation (KinMS) tool and a Bayesian Markov Chain Monte Carlo method to measure an SMBH mass of (4.2 ± 0.7) × 109 M⊙, a F160W-band stellar mass-to-light ratio that varies from 2.8 ± 0.6 M⊙/L$_{\odot ,\, \mathrm{F160W}}$ in the centre to 2.4 ± 0.3 M⊙$/\rm L_{\odot ,\, \mathrm{F160W}}$ at the outer edge of the disc and a molecular gas velocity dispersion of 8.3 ± 2.1 km s−1(all 3σ uncertainties). We also detect unresolved continuum emission across the full bandwidth, consistent with synchrotron emission from an active galactic nucleus. This work demonstrates that low-J CO emission can resolve gas very close to the SMBH ($\approx 140\, 000$ Schwarzschild radii) and hence that the molecular gas method is highly complimentary to megamaser observations, as it can probe the same emitting material.</jats:p>


JINGLE, a JCMT legacy survey of dust and gas for galaxy evolution studies - I. Survey overview and first results

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 481 (2018) 3497-3519

A Saintonge, CD Wilson, T Xiao, L Lin, HS Hwang, T Tosaki, M Bureau, PJ Cigan, CJR Clark, DL Clements, I De Looze, T Dharmawardena, Y Gao, WK Gear, J Greenslade, I Lamperti, JC Lee, C Li, MJ Michalowski, A Mok, H-A Pan, AE Sansom, M Sargent, MWL Smith, T Williams, C Yang, M Zhu, G Accurso, P Barmby, E Brinks, N Bourne, T Brown, A Chung, EJ Chung, A Cibinel, K Coppin, J Davies, TA Davis, S Eales, L Fanciullo, T Fang, Y Gao, DHW Glass, HL Gomez, T Greve, J He, LC Ho, F Huang, H Jeong, X Jiang, Q Jiao, F Kemper, JH Kim, M Kim, T Kim, J Ko, X Kong, K Lacaille, CG Lacey, B Lee, JH Lee, W-K Lee, K Masters, S-H Oh, P Papadopoulos, C Park, S-J Park, H Parsons, K Rowlands, P Scicluna, JM Scudder, R Sethuram, S Serjeant, Y Shao, Y-K Sheen, Y Shi, H Shim, CMA Smith, K Spekkens, A-L Tsai, A Verma, S Urquhart, G Violino, S Viti, D Wake, J Wang, J Wouterloot, Y Yang, K Yim, F Yuan, Z Zheng


CO Tully-Fisher relation of star-forming galaxies at=0.05-0.3

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 479 (2018) 3319-3334

S Topal, M Bureau, AL Tiley, TA Davis, K Torii


WISDOM Project - III. Molecular gas measurement of the supermassive black hole mass in the barred lenticular galaxy NGC4429

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 473 (2018) 3818-3834

TA Davis, M Bureau, K Onishi, F van de Voort, M Cappellari, S Iguchi, L Liu, EV North, M Sarzi, MD Smith


The effects of galaxy interactions on molecular gas properties

Astrophysical Journal American Astronomical Society 868 (2018) 132

H-A Pan, L Lin, B-C Hsieh, M Bureau

Galaxy interactions are often accompanied by an enhanced star formation rate (SFR). Since molecular gas is essential for star formation, it is vital to establish whether and by how much galaxy interactions affect the molecular gas properties. We investigate the effect of interactions on global molecular gas properties by studying a sample of 58 galaxies in pairs and 154 control galaxies. Molecular gas properties are determined from observations with the JCMT, PMO, and CSO telescopes and supplemented with data from the xCOLD GASS and JINGLE surveys at 12CO(1–0) and 12CO(2–1). The SFR, gas mass (${M}_{{{\rm{H}}}_{2}}$), and gas fraction (f gas) are all enhanced in galaxies in pairs by ~2.5 times compared to the controls matched in redshift, mass, and effective radius, while the enhancement of star formation efficiency (SFE ≡SFR/${M}_{{{\rm{H}}}_{2}}$) is less than a factor of 2. We also find that the enhancements in SFR, ${M}_{{{\rm{H}}}_{2}}$ and f gas, increase with decreasing pair separation and are larger in systems with smaller stellar mass ratio. Conversely, the SFE is only enhanced in close pairs (separation &lt;20 kpc) and equal-mass systems; therefore, most galaxies in pairs lie in the same parameter space on the SFR–${M}_{{{\rm{H}}}_{2}}$ plane as controls. This is the first time that the dependence of molecular gas properties on merger configurations is probed statistically with a relatively large sample and a carefully selected control sample for individual galaxies. We conclude that galaxy interactions do modify the molecular gas properties, although the strength of the effect is dependent on merger configuration.


The KMOS Redshift One Spectroscopic Survey (KROSS): the origin of disc turbulence in z approximate to 1 star-forming galaxies

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 474 (2018) 5076-5104

HL Johnson, CM Harrison, AM Swinbank, AL Tiley, JP Stott, RG Bower, I Smail, AJ Bunker, D Sobral, OJ Turner, P Best, M Bureau, M Cirasuolo, MJ Jarvis, G Magdis, RM Sharples, J Bland-Hawthorn, B Catinella, L Cortese, SM Croom, C Federrath, K Glazebrook, SM Sweet, JJ Bryant, M Goodwin, IS Konstantopoulos, JS Lawrence, AM Medling, MS Owers, S Richards


Shape of LOSVDs in barred disks: implications for future IFU surveys

Astrophysical Journal IOP Publishing 854 (2018) 65

Z-Y Li, VP Debattista, M Bureau, J Shen, Y Zhou, M Du

The shape of LOSVDs (line-of-sight velocity distributions) carries important information about the internal dynamics of galaxies. The skewness of LOSVDs represents their asymmetric deviation from a Gaussian profile. Correlations between the skewness parameter ($h_3$) and the mean velocity ($\vm$) of a Gauss-Hermite series reflect the underlying stellar orbital configurations of different morphological components. Using two self-consistent $N$-body simulations of disk galaxies with different bar strengths, we investigate $h_3-\vm$ correlations at different inclination angles. Similar to previous studies, we find anticorrelations in the disk area, and positive correlations in the bar area when viewed edge-on. However, at intermediate inclinations, the outer parts of bars exhibit anticorrelations, while the core areas dominated by the boxy/peanut-shaped (B/PS) bulges still maintain weak positive correlations. When viewed edge-on, particles in the foreground/background disk (the wing region) in the bar area constitute the main velocity peak, whereas the particles in the bar contribute to the high-velocity tail, generating the $h_3-\vm$ correlation. If we remove the wing particles, the LOSVDs of the particles in the outer part of the bar only exhibit a low-velocity tail, resulting in a negative $h_3-\vm$ correlation, whereas the core areas in the central region still show weakly positive correlations. We discuss implications for IFU observations on bars, and show that the variation of the $h_3-\vm$ correlation in the disk galaxy may be used as a kinematic indicator of the bar and the B/PS bulge.


WISDOM Project – II. Molecular gas measurement of the supermassive black hole mass in NGC 4697

Monthly Notices of the Royal Astronomical Society Oxford University Press 468 (2017) 4675-4690

TA Davis, M Bureau, K Onishi, M Cappellari, S Iguchi, M Sarzi

As 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-rotating early-type galaxy NGC 4697. This estimate is based on Atacama Large Millimeter/submillimeter Array (ALMA) cycle-3 observations of the 12CO(2–1) emission line with a linear resolution of 29 pc (0.53 arcsec). We find that NGC 4697 hosts a small relaxed central molecular gas disc with a mass of 1.6 × 107 M⊙, co-spatial with the obscuring dust disc visible in optical Hubble Space Telescope imaging. We also resolve thermal 1 mm continuum emission from the dust in this disc. NGC 4697 is found to have a very low molecular gas velocity dispersion, σgas = 1.65+0.68−0.65 km s^−1. This seems to be partially because the giant molecular cloud mass function is not fully sampled, but other mechanisms such as chemical differentiation in a hard radiation field or morphological quenching also seem to be required. We detect a Keplerian increase of the rotation of the molecular gas in the very centre of NGC 4697, and use forward modelling of the ALMA data cube in a Bayesian framework with the KINematic Molecular Simulation (KINMS) code to estimate an SMBH mass of (1.3+0.18−0.17) × 108 M⊙ and an i-band mass-to-light ratio of 2.14+0.04−0.05M⊙/L⊙ (at the 99 per cent confidence level). Our estimate of the SMBH mass is entirely consistent with previous measurements from stellar kinematics. This increases confidence in the growing number of SMBH mass estimates being obtained in the ALMA era.


WISDOM project – I. Black hole mass measurement using molecular gas kinematics in NGC 3665

Monthly Notices of the Royal Astronomical Society Oxford University Press 468 (2017) 4663-4674

S Iguchi, K Onishi, TA Davis, MG Bureau, M Cappellari, L Blitz, M Sarzi

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 the Combined Array for Research in Millimeter Astronomy (CARMA) B and C array observations of the 12CO(J = 2 − 1) emission line with a combined angular resolution of 0.59 arcsec. We analysed and modelled the three-dimensional molecular gas kinematics, obtaining a best-fitting SMBH mass MBH=5.75+1.49−1.18×10^8 M⊙, a mass-to-light ratio at H-band (M/L)H = 1.45 ± 0.04 (M/L)⊙,H and other parameters describing the geometry of the molecular gas disc (statistical errors, all at 3σ confidence). We estimate the systematic uncertainties on the stellar M/L to be ≈0.2 (M/L)⊙,H, and on the SMBH mass to be ≈0.4 × 108 M⊙. 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.


The KMOS Redshift One Spectroscopic Survey (KROSS): rotational velocities and angular momentum of z ≈ 0.9 galaxies★

Monthly Notices of the Royal Astronomical Society Oxford University Press 467 (2017) 1965-1983

CM Harrison, AM Swinbank, HL Johnson, JP Stott, RG Bower, I Smail, AL Tiley, AJ Bunker, M Cirasuolo, D Sobral, RM Sharples, P Best, M Bureau, M Jarvis, G Magdis

We present dynamical measurements for 586 Hα-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 M ⊙ yr -1 and a stellar mass range of log (M * [M ⊙ ]) ≈ 9-11. We find that the rotation velocity-stellar mass relationship (the inverse of the Tully- Fisher relationship) for our rotationally dominated sources (v C /σ 0 &gt; 1) has a consistent slope and normalization as that observed for z = 0 discs. 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 discs. The specific angular momentum scales as j s ∝ M * 0.6±0.2 , consistent with that expected for dark matter (i.e. j DM ∝ M DM 2/3 ). We find that z≈ 0.9 star-forming galaxies have decreasing specific angular momentum with increasing Sérsic index. Visually, the sources with the highest specific angular momentum, for a given mass, have the most disc-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.


A star formation study of the ATLAS3D early-type galaxies with the AKARI all-sky survey

Astronomy and Astrophysics EDP Sciences 605 (2017) A74-

T Kokusho, H Kaneda, M Bureau, T Suzuki, K Murata, A Kondo, M Yamagishi

The star formation properties of early-type galaxies (ETGs) are currently the subject of considerable interest, particularly whether they differ from those of gas-rich spirals. We perform a systematic study of star formation in a large sample of local ETGs using polycyclic aromatic hydrocarbon (PAH) and dust emission, focusing on the galaxies' star formation rates (SFRs) and star formation efficiencies (SFEs). Our sample is composed of the 260 ETGs from the ATLAS3D survey, from which we use the cold gas measurements (HI and CO). The SFRs are estimated from stellar, PAH and dust fits to spectral energy distributions created from new AKARI measurements and literature data from WISE and 2MASS. The mid-infrared luminosities of non-CO-detected galaxies are well correlated with their stellar luminosities, showing that they trace (circum)stellar dust emission. CO-detected galaxies show an excess above these correlations, uncorrelated with their stellar luminosities, indicating that they likely contain PAHs and dust of interstellar origin. PAH and dust luminosities of CO-detected galaxies show tight correlations with their molecular gas masses, and the derived current SFRs are typically 0.01-1 Msun/yr. These SFRs systematically decrease with stellar age at fixed stellar mass, while they correlate nearly linearly with stellar mass at fixed age. The majority of local ETGs follow the same star-formation law as local star-forming galaxies, and their current SFEs do not depend on either stellar mass or age. Our results clearly indicate that molecular gas is fueling current star formation in local ETGs, that appear to acquire this gas via mechanisms regulated primarily by stellar mass. The current SFEs of local ETGs are similar to those of local star-forming galaxies, indicating that their low SFRs are likely due to smaller cold gas fractions rather than a suppression of star formation.


Large-scale filamentary structures around the Virgo Cluster revisited

Astrophysical Journal Institute of Physics 833 (2016) 207-

M Bureau, S-C Rey, S Kim, A Chung, H Yoon, T Lisker, H Jerjen, E-C Sung, H Jeong, Y Lee, W Lee, J Chung

<p>We revisit the filamentary structures of galaxies around the Virgo cluster, exploiting a larger dataset based on the HyperLeda database than previous studies. In particular, this includes a large number of low-luminosity galaxies, resulting in better sampled individual structures. We confirm seven known structures in the distance range 4 h^-1 Mpc &lt; SGY &lt; 16 h^-1 Mpc, now identified as filaments, where SGY is the axis of the supergalactic coordinate system roughly along the line of sight. The Hubble diagram of the filament galaxies suggests they are infalling toward the main-body of the Virgo cluster. We propose that the collinear distribution of giant elliptical galaxies along the fundamental axis of the Virgo cluster is smoothly connected to two of these filaments (Leo II A and B). Behind the Virgo cluster (16 h^-1 Mpc &lt; SGY &lt; 27 h^-1 Mpc), we also identify a new filament elongated toward the NGC 5353/4 group ("NGC 5353/4 filament") and confirm a sheet that includes galaxies from the W and M clouds of the Virgo cluster ("W-M sheet"). In the Hubble diagram, the NGC 5353/4 filament galaxies show infall toward the NGC 5353/4 group, whereas the W-M sheet galaxies do not show hints of gravitational in uence from the Virgo cluster. The filamentary structures identified can now be used to better understand the generic role of filaments in the build-up of galaxy clusters at z ≈ 0.</p>

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