arXiv:1102.4633v2 [astro-ph.CO] 26 Feb 2011 Fr rcEmsellem Eric ireYe Lablanche Pierre-Yves ihr .McDermid M. Richard acSarzi Marc iaM Young M. Lisa galaxies ac 2011 March 1 ⋆ h ATLAS The o.Nt .Ato.Soc. Astron. R. Not. Mon. 17 16 15 14 13 12 11 10 9 8 7 6 2 1 3 5 4 c aoaor I ai-aly E/RUSpCR Universi CNRS CEA/IRFU/SAp Paris-Saclay, AIM Laboratoire Recherc de Centre Lyon, de Observatoire 1, Universit´e Lyon Karl-Schwarzschild-Str. Observatory, Cali Southern of European University Hall, Campbell Astronomy, of Department duc srnmr ainlRdoAtooyObservatory Astronomy Tech Radio and National Astronomer, Mining Adjunct of Institute Mexico New Department, Physics u-eateto srpyis eateto hsc,Un Physics, of Department Astrophysics, of Sub-department eiiOsraoy otenOeain etr 7 .A N. 670 Center, Operations 750 Northern l’Observatoire, Observatory, de Gemini Av. 61 LERMA, Paris, de Observatoire vneCalsAd´,F620SitGnsLvl France Laval, Saint-Genis Andr´e, F-69230 Charles avenue 9 ae nosrain are u ihteIA 0 Telescop 30m IRAM the with out carried observations on Based ulpFellow University Dunlap Astrophysics, & Astronomy for Institute Hertfords Dunlap of University Research, Astrophysics for Centre Karl-Schwarzschi f¨ur Astrophysik, Max-Planck-Institut aty srnmclIsiue nvriyo Groningen, of University Institute, Astronomical Kapteyn ehrad nttt o eerhi srnm (ASTRON), Astronomy in Research for Institute Netherlands B PO Physik, f¨ur extraterrestrische Max-Planck-Institut treah edn ednUiest,Psbs91,2300 9513, Postbus University, Leiden Leiden, Sterrewacht 00RAS 0000 ed ´ rcBournaud eric ´ ⋆ 15 ihlsScott Nicholas , 7 1 000 3D , , 8 2 0–0 00)Pitd1Mrh21 M L (MN 2011 March 1 Printed (0000) 000–000 , aehKhochfar Sadegh , , † 9 rjc V h oeua a otn fearly-type of content gas molecular the IV: – project atnBureau Martin ihl Cappellari Michele , opooyrte hnclu,adtebl fte i nthe on 0.22 lie = them 56/259 of is bulk rate the detection and colour, than rather morphology r loafweteeyC-iherytp aaiswt H with galaxies early-type CO-rich extremely few a G several also through are gas th molecular within their virialized retained molec have be members to their seem on they influence spirals) cluster’s (unlike the though that shows cluster the ebr;saitclaayi fterH detect their CO of dozen analysis a are statistical There members; mass. dynamical on dependence est e words: galaxie Key early-type of sub-classes various of speculate formation We the re-accretion. its preventing or proces gas formation an molecular their low that of suggesting galaxies rates, detection The CO momentum. trend significant angular a specific find stellar do the We environments. density low in are e fiskn n stefis oicuemn ig lse me Cluster mass Virgo stellar many median include a to the with first is galaxies the This is hot content. and dynamically gas kind cold its in of their vey emission to J=2-1 histories and assembly J=1-0 ATLASand CO volume-limited for the survey of a ies out carried have We ABSTRACT aais tutr ai ie:galaxies. lines: Radio — structure galaxies: 8 5 afel Morganti Raffaella , ahrn Alatalo Katherine , 3 al Serra Paolo , dSr ,871Grhn,Germany Garching, 85741 1, ld-Str. aais litcladlniua,c aais evolut galaxies: — cD lenticular, and elliptical galaxies: x11,D848Grhn,Germany Garching, D-85478 1312, ox ,878Grhn,Germany Garching, 85748 2, ie afil,HrsA10A,UK 09AB, AL1 Herts Hatfield, hire, otu 0,90 VGoign h Netherlands The Groningen, AV 9700 800, Postbus 3 ′ vriyo xod ey ikno ulig el od O Road, Keble Building, Wilkinson Denys Oxford, of iversity eAtohsqed ynadEoeNraeSpeiued Ly Sup´erieure de Normale Ecole and Lyon de Astrophysique he fTrno 0S.Gog tet oot,O 5 H,Canada 3H4, M5S ON Toronto, Street, George St. 50 Toronto, of hk lc,Hl,H 62,USA 96720, HI Hilo, Place, ohoku oor,N 70,USA 87801, NM Socorro, , ALie,teNetherlands the Leiden, RA ona ekly A970 USA 94720, CA Berkeley, fornia, ioh .Davis A. Timothy , 4Prs France Paris, 14 otu ,79 ADiglo h Netherlands the Dwingeloo, AA 7990 2, Postbus 11 ooy oor,N 70,USA 87801, NM Socorro, nology, ´ ai ieo,911GfsrYet ee,France Cedex, Gif-sur-Yvette 91191 Diderot, t´e Paris .IRAM e. ao Krajnovi Davor , 3 oe .Davies L. Roger , 12 6 e Blitz Leo , 12 n neMreWeijmans Anne-Marie and , ± , .3 ihn eedneon dependence no with 0.03, † 13 3D -al [email protected] E-mail: hrtnNaab Thorsten , A T ape ihtega fcnetn hi trformation star their connecting of goal the with sample, E tl l v2.2) file style X 2 asdsrbtosadterdnmclsau within status dynamical their and distributions mass c 3 ´ 6 rnos Combes Francoise , 7 aieBois Maxime , aadKuntschner Harald , 3 .T eZeeuw de T. P. , ∼ e eemr fetv tdestroying at effective more were ses 3 s. lse.W ugs httecluster the that suggest We cluster. e nteipiain fteedt for data these of implications the on × 14 lrmse ssbl tbs,even best, at subtle is masses ular rrsdne ntecutr There cluster. the in residences yr 2 ags ouelmtdC sur- CO volume-limited largest 10 o Oosterloo Tom , ua oetmas aelow have also momentum gular ewe oeua otn and content molecular between K masses e eune h vrl CO overall The sequence. red osaogteVroCluster Virgo the among ions 10 br.Sml ebr are members Sample mbers. fr,O13H UK 3RH, OX1 xford, uioiyadol mod- a only and luminosity M on, h 6 al-yegalax- early-type 260 the 7 , o aais S — ISM galaxies: — ion ⊙ 8 & 16 , hyaeslce by selected are they ; 10 , 17 4 7 9 , 7 , 10 M , ⊙ , n these and , 12 , 13 , 2 L. M. Young et al.
1 INTRODUCTION
Understanding galaxy formation and evolution is at the heart of much of current astrophysics. The task is, however, greatly hin- dered by the lack of quantitative, physically-driven (as opposed to empirical) models of the regulation of molecular gas and star for- mation on galactic scales. All galaxies or protogalaxies must have begun as gas-rich entities, and during their first epochs of star for- mation would have belonged to the “blue cloud” in a galaxy colour- magnitude diagram. In contrast, today there is a clear separation between the blue cloud (composed mainly of star-forming disc and dwarf galaxies) and the red sequence (old and dynamically hot stel- lar systems). Thus, an outstanding question in galaxy evolution is how the present-day early-type galaxies moved quickly from the blue cloud to the red sequence. This rapid movement to the red sequence requires, at mini- mum, an abrupt cessation of star formation at high redshift so that the global colours change from blue to red (Thomas et al. 2005, 2010). Since today’s early-type galaxies are generally rather poor in atomic and molecular gas (Lees et al. 1991), it is often assumed that the cessation of star formation was achieved by removing, destroy- ing, or consuming the cold gas. The most massive early-type galax- ies are often rich in hot gas (O’Sullivan et al. 2001), so it is possible that molecular gas is destroyed by heating. An intriguing alternative suggestion is that the cold gas might be retained but rendered un- suitable for star formation activity (Martig et al. 2009). Thus, the story of the development of the red sequence is, to a large extent, a story of what happens to the cold gas in galaxies. Several mechanisms have been proposed to deplete the cold gas from galaxies and move them onto the red sequence. For exam- ple, a major merger between two gas-rich galaxies could (depend- ing on geometry) result in a large-scale loss of angular momentum, dropping gas to the center of the merger remnant (Barnes 2002). The gas could then be funneled into a black hole and/or consumed in a LIRG-type burst of star formation activity. Alternatively, the en- ergy input into the interstellar medium from an active nucleus or a starburst could hypothetically destroy and/or unbind the cold gas, as well as prevent hot gas from cooling. Environmental effects such as ram pressure stripping, gravitational interactions and galaxy harass- ment could also be important in at least some early-type galaxies. In fact, it is likely that all of these processes are important at some level, but we do not yet have strong constraints on their relative im- pacts. The behavior of the cold gas in all of these transformational processes needs to be better understood. It has also been known for some years that today’s early- type galaxies, while relatively poor in cold gas compared to spirals, are not completely devoid of cold gas. The gas is de- tected in dusty silhouette discs (e.g. Goudfrooij et al. 1994), HI emission (e.g. Wardle & Knapp 1986; Huchtmeier, Sage & Henkel 1995; Morganti et al. 2006; Oosterloo et al. 2010), and CO emis- sion (Lees et al. 1991; Wiklind et al. 1995; Combes et al. 2007; Welch, Sage, & Young 2010). The origin of this gas is not well understood; it could have come from internal stellar mass loss (e.g. Mathews & Brighenti 2003; Ciotti, Ostriker & Proga 2010), or it could have been acquired from an external source such as another galaxy or cold mode accretion. In some early-type galaxies the case for an external origin is very clear because the specific angular momentum of the gas is dramatically different from that of the stars. Cen A (Quillen et al. 1992) and NGC 3032 (Young, Bureau & Cappellari 2008) exhibit this property, but in many other cases the gas kinematics are consistent with an internal origin. Again, probably both external and internal processes con-