Starburst galaxies at low and high redshift Paul van der Werf Sterrewacht Leiden ESO, Santiago April 2006
Download ReportTranscript Starburst galaxies at low and high redshift Paul van der Werf Sterrewacht Leiden ESO, Santiago April 2006
Starburst galaxies at low and high redshift Paul van der Werf Sterrewacht Leiden ESO, Santiago April 2006 Credits starbursts at low redshift starbursts at high redshift Leonie Snijders (VISIR) Liesbeth Vermaas (SINFONI) Kate Isaak (Cardiff) Padelis Papadopoulos (ETH Zürich) Kirsten Kraiberg Knudsen (PhD October 2004) Tracy Webb (McGill University, Montreal) Lottie van Starkenburg (SINFONI) and the FIRES team: Marijn Franx Pieter van Dokkum (Yale) Ivo Labbé (Carnegie) Greg Rudnick (NOAO) Hans-Walter Rix (MPIA) Mariska Kriek Natascha Förster Schreiber (MPE) Alan Moorwood (ESO) Starburst galaxies at low and high redshift 2 « The stellar systems are scattered through space as far as telescopes can penetrate. We find them smaller and fainter, in constantly increasing numbers, and we know that we are reaching out into space, until, with the faintest nebulae than can be detected with greatest telescopes, we arrive at the frontiers of the known Universe. » Edwin Hubble, The Realm of the Nebulae (1936) Starburst galaxies at low and high redshift 3 What is a starburst galaxy? A starburst galaxy is a galaxy with such a high star formation rate that it will turn all of its gas into stars in tb << tHubble Milky Way: M H2 M tb 2.5 109 M 1M yr 1 22 correction factor for mass return from stars M H2 M M H2 1010 yrs 0.5M gas gradual buildup of disk Starburst galaxies at low and high redshift 4 A luminous infrared galaxy: the Antennae Crossing orbits give gas concentration in interaction zone Intense obscured star formation in overlap region SCUBA 850 mm Most intense star formation is obscured LFIR M 3 1011 L 30M yr 1 (Webb, Snijders & Van der Werf , in preparation) Starburst galaxies at low and high redshift 5 An ultraluminous infrared galaxy: Arp220 LFIR M 1.5 1012 L 150M yr 1 Starburst galaxies at low and high redshift Arp220 6 Starformation in ULIRGs Arp220: 1.6 1010 M M H2 M 150 M yr 1 tb 2 M H2 M 2 108 yrs NB: tb few 108 yrs merger timescale dynamical timescale (crossing/rotation time) free-fall time protogalaxy? Such high SFRs can build up an entire galaxy in t << tHubble relation to galaxy formation? correction factor for mass return from stars Starburst galaxies at low and high redshift 7 Simple-minded estimate of "maximum star formation rate" In the absence of external pressure, the maximum star formation rate occurs when a gas mass is turned into stars on the free-fall timescale. M max M gas tff M gas G selfgravitating sphere: R M max G 2 2 3 4 100 M 100 km/s 3 yr 1 initial starburst – rapid formation of bulk of the stellar population formation of spheroids? Implication: high SFRs are found in the most massive galaxies Starburst galaxies at low and high redshift 8 Do “maximum starburst” galaxies exist? ultraluminous IR galaxies (ULIRGs) maximum starbursts luminous IR galaxies (LIRGs) normal galaxies (Kennicutt 1998) Starburst galaxies at low and high redshift 9 ULIRGs as “maximum starbursts” M A 10 M yr 1 10 ULIRGs (Lbol 1012 L ) have M A f (IMF parameters) 1 M max! ULIRGs Lbol L LFIR At L 10 L is 90% Lbol (cf., 30–50% for normal spirals) 12 Starburst galaxies at low and high redshift 10 Starformation efficiency Starbursts cannot be simply scaled up. More intense starbursts are also more efficient with their fuel. ULIRGs: LFIR M H2 LIR/LCO SFR/MH2 100 L M 1 SFE Milky Way: 1.5 L M 1 Galactic GMCs: 1.8 L M 1 OMC-1: 54 L M 1 Orion BN-KL: (Gao & Solomon 2001) LIR SFR 400 L M 1 Starburst galaxies at low and high redshift 11 Role of dense gas LIR/LCO SFR/MH2 SFE (Gao & Solomon 2001) LHCN/LCO mass fraction of dense gas More dense gas means more efficient star formation. Starburst galaxies at low and high redshift 12 NGC 4038/4039 NGC 4038/4039 detail Superstarclusters: does size matter? NGC4038/4039 cluster: 100 pc Orion: 1.5 pc Orion (M42) Starburst galaxies at low and high redshift 30 Doradus 13 Superstarclusters: densities nH [M pc—3] [cm—3] in 4.5pc in 4.5pc 5200 1.6∙105 Object d [pc] M [M] [W99]2 100 2∙106 R136 10 3∙104 80 2500 M42 2 1800 5 200 Starburst galaxies at low and high redshift 14 The Antennae with Spitzer and VISIR contours: dust continuum IRAC/Spitzer (Wang et al., 2004) Starburst galaxies at low and high redshift [NeII] 12.8 mm ESO/VLT VISIR (Snijders et al., in prep.) 15 Probing dense molecular gas Line Tex [K] ncrit [cm—3] CO 10 5.5 1.7∙103 CO 43 55 8.0∙104 CO 65 116 2.5∙105 HCN 10 4.3 1.4∙105 HCN 43 42 5.5∙106 Starburst galaxies at low and high redshift molecular gas temperature of dense gas dense molecular gas 16 Dense gas in the ULIRG Mrk231 (Papadopoulos & Van der Werf 2001) Mrk231 CO 65 and 43 Starburst galaxies at low and high redshift RxW/JCMT (Papadopoulos, Isaak & Van der Werf 2006) 17 Again: dense gas in Mrk231 Mrk231 CO 32 and 10HCN 43 Starburst galaxies at low and high redshift RxB3/JCMT (Papadopoulos, Isaak & Van der Werf 2006) 18 Two phases of molecular gas Combine these data with CO 10, 21 and 13CO 21 (upper limit): no model reproduces all CO lines: CO 43/65 and CO 10/21/32 probe different gas phases. diffuse phase: T 50—85 K and n 300—103 cm—3, dense phase: T 50—65 K and n 104 cm—3. Total mass of molecular gas from CO: M 3.5∙1010 M (or up to a factor 4—5 lower). Mass of dense molecular gas from HCN: M 1.5—3.5∙1010 M. Almost all molecular gas in Mrk231 is dense. Starburst galaxies at low and high redshift 19 ULIRGs and galaxy formation Locally, ULIRGs are energetically unimportant: contribute only 2% of local bolometric energy density How important are ULIRGs at high z? observe redshifted far-IR emission in submillimetre with JCMT/SCUBA Local ULIRGs almost always have a hidden AGN: causal link with the extreme starburst? Are high-z ULIRGs the sites of the coeval formation of spheroids and supermassive black holes? question for the coming decade Starburst galaxies at low and high redshift 20 Cosmic energy density 1mm Microwave Background 1mm IR/Optical Background 1nm (Puget et al. 1996, Hauser et al. 1998 Fixsen et al. 1998) X-Ray Background Stars+BlackHoles Big Bang Starburst galaxies at low and high redshift AGN 21 Is obscured star formation important? Direct starlight: nIn = 1.7 . 10-5 erg/s/cm2/sr Far-IR background: nIn = 3.1 . 10-5 erg/s/cm2/sr Obscured star formation dominates. Starburst galaxies at low and high redshift 22 Submillimetre cosmology Large negative k-correction: Submm samples have high proportion of high-z galaxies Galaxies up to z 10 detectable Brightness-limited volume-limited Luminosities without precise redshifts Sources do not fade much from z=1 to 10 Deeper surveys probe fainter galaxies, not higher z Starburst galaxies at low and high redshift 23 Counts and backgrounds Resolved background at 850mm: 25% down to 2 mJy Connection to other populations at fainter flux levels. Lensing can probe these. Submm background comes from small number of (ultra)luminous galaxies Starburst galaxies at low and high redshift 24 SCUBA/JCMT lensed galaxy survey 12 gravitationally lensing clusters 1 blank field (NTT Deep Field) Survey area 72 arcmin2 Deepest fields are confusionlimited (2 mJy) 55 sources detected at 850 mm Knudsen PhD thesis Van der Werf Starburst galaxies at low and high redshift 25 Faint submillimetre source counts Counts imply strong evolution First time the faint submm population is substantially probed Connection with optical population Turnover in counts detected for the first time (Knudsen, Van der Werf & Kneib, in prep.) Starburst galaxies at low and high redshift 26 Submillimetre source counts and evolution luminosity evolution: L (1+z)p density evolution: N (1+z)q Counts + background imply pure luminosity evolution proportional to (1+z)3 Starburst galaxies at low and high redshift 27 Submm galaxies in the NTT Deep Field Not an ERO (?) ERO (Knudsen et al. in preparation) Starburst galaxies at low and high redshift 28 FIRES: Faint Infrared Extragalactic Survey ISAAC/Antu HDF-S: Labbé et al., 2003 MS1054—03: Förster Schreiber et al., 2006 Starburst galaxies at low and high redshift 29 Starburst galaxies at low and high redshift 30 FIRES allows better mass selection I814 Ks the 6 most massive z 3 galaxies in the HDF-S FIRES allows selection of high-z galaxies in the rest-frame V-band much closer to a mass-selection than rest-frame UV a new class of high-z galaxies: Distant Red Galaxies (DRGs) Starburst galaxies at low and high redshift 31 Rest-frame SEDs: Lyman break galaxies Starburst galaxies at low and high redshift 32 Rest-frame SEDs: distant red galaxies (Förster Schreiber et al., 2004) Starburst galaxies at low and high redshift 33 Selection of distant red galaxies (Franx et al., 2003) Starburst galaxies at low and high redshift 34 DRGs are (mostly) star forming galaxies star formation rates > 100 M yr—1 (Van Dokkum et al., 2004) Starburst galaxies at low and high redshift 35 SCUBA observations of MS1054–03 M1383 S850 = 5 mJy Starburst galaxies at low and high redshift 36 Submm galaxies and DRGs Lyman Break Galaxies have no detectable submm emission even after massive source stacking Distant Red Galaxies are massive and have high SFRs DRGs: 3 arcmin–2 for K<22.5 same source density as submm galaxies with >0.8 mJy at 850 mm 1 FIRES field observed with SCUBA: 1 DRG detected directly (5 mJy) connection between sub-mJy submm galaxies and DRGs? Starburst galaxies at low and high redshift 37 Stacking DRGs DRGs, EROs DRGs: S850 = 1.11 0.28 mJy (Knudsen et al., 2005) random positions Starburst galaxies at low and high redshift 38 Breaking the confusion barrier: gravitational lenses A2218 Starburst galaxies at low and high redshift 39 A2218: SCUBA 850 mm Starburst galaxies at low and high redshift 40 The submm triple behind A2218 Triple image, z=2.515 Magnification in total factor 40 Intrinsic 850 mm flux: 0.8 mJy Redshifted H: strong star formation J–K=2.7: Distant Red Galaxy (Kneib et al., 2004a) Starburst galaxies at low and high redshift 41 CO 3–2 detection of the submm triple (Sheth et al., 2004; Kneib et al., 2005b) Detected both at Owens Valley and Plateau de Bure CO line width less massive than bright SMGs but comparable to DRGs Starburst galaxies at low and high redshift 42 Conclusions and outlook: low z Gas density is crucial in determining starburst properties; also related to depth of potential well? Luminous starbursts tend to have both high L/M and high M Molecular lines probe density/temperature structure The future: SINFONI+LGS, APEX, HIFI/Herschel, ALMA Starburst galaxies at low and high redshift 43 Conclusions and outlook: high z Starbursts are a key process in galaxy evolution We are looking back towards a strongly obscured universe, energetically dominated by dusty starbursts DRGs are massive and have high SFRs; as a population they are at least as important as LBGs for cosmic mass budget and SFR Connection between DRGs and faint submm galaxies The future: SCUBA2, ALMA, HAWK-I, JWST, ELT Starburst galaxies at low and high redshift 44 To coldly go…: SCUBA-2 SCUBA-2 will bring rectangular array imaging to submm astronomy 8 4032 sub-arrays – 4 at 850 mm, 4 at 450 mm Mapping speed unequalled Operational mid-2007 Legacy programs defined: Cosmological survey Full Galactic plane survey Full Gould’s Belt survey Shallow “all-sky” survey Unbiased debris disk survey Starburst galaxies at low and high redshift 45 SCUBA-2 Cosmology Legacy Survey 1 deg2 field, will be mapped to confusion limit in 23 hours by SCUBA-2 at 850 mm 4 PIs: Dunlop, Halpern, Smail, Van der Werf Large survey (20 deg2) at 850 mm, deep survey at 450 mm (0.5 deg2) 450 mm survey will resolve full submm background and detect all LIRGs in the survey area out to z=2 (ULIRGs out to z=4) Connection with other populations: optical, near-IR, X-ray, radio,… SCUBA-2 field-of-view Starburst galaxies at low and high redshift Time allocation 102 good nights (including 50% of the best weather until mid-2009) 46 « We are, by definition, in the very center of the observable region. We know our immediate neighborhood rather intimately. With increasing distance, our knowledge fades, and fades rapidly. Eventually, we reach the dim boundary, the utmost limits of our Telescopes. There, we measure shadows, and we search among ghostly errors of measurement for landmarks that are scarcely more substantial. The search will continue. Not until the empirical resources are exhausted, need we pass on the dreamy realms of speculation. » Edwin Hubble, The Realm of the Nebulae (1936) Starburst galaxies at low and high redshift 47