Normal/Starburst Galaxies at Low/Intermediate-z with ALMA Bologna, 2005 June 6

ALMA: Summary of detailed requirements ALMA: Summary of detailed requirements <0.01” (18.5 km baseline at 650 GHz) Spatial resolution Sub-mJy in <10 min (median conditions) Flux sensitivity 64 antennas of 12m diameter Antenna complement All cross products simultaneouslyPolarization 10000:1 (spectral); 50000:1 (imaging) Dynamic range 31.5 kHz (0.01 km/s) at 100 GHz Spectral resolution 8 GHz, fully tunableBandwidth 30 to 950 GHz (initially only GHz) Frequency

Strong limitation of Current mm Interferometers WHY ALMA? OVRO Nobeyama Millimeter Array   In sensitivity ( PdBI, the most sensitive ) In Ang. Res. (bs max = 2km for BIMA, ~500m others) In Freq. Coverage (ALMA open sub-mm window) In Imaging capability (6 to 10 antennas only)  mm vs. PdBI sensitivity Continuum  factor 100 better (6 µ Jy/beam in 1 hr) Spectral line  factor 30 better (1.1 mJy/beam in 10 hr)  ALMA factor better in resolution IRAM

Capabilities of Current mm Interferometers 6x15m6x10.4m10x6.1m6x10m +(45m) 400m440m2km350m (2060) ( ) Dual-Freq Obs. Over Full BW Dual-Freq Obs. Large FOV+ UV Cov. Rainbow Coll. Area Highest Sensitivity at All Freq. Sensitivity + FOV High-res For Strong Sources 2mm Capability IRAM OVRO BIMA Nobeyama Antennas Longest Baselines Frequency Range (GHz) Collecting Area (m 2 ) Advantages

Primary Goals for ALMA in Extragalactic Astronomy ÜThe ability to detect spectral line emission from CO or CI in a normal galaxy like the Milky Way at a redshift of 3, in less than 24 hours of observation. ÜThe ability to provide precise images at an angular resolution of 0.1” or better (0.01” at 650 GHz) to map the dust/molecular clouds structure in distant galaxies ÜThe ability to detect spectral line emission from CO or CI in a normal galaxy like the Milky Way at a redshift of 3, in less than 24 hours of observation. ÜThe ability to provide precise images at an angular resolution of 0.1” or better (0.01” at 650 GHz) to map the dust/molecular clouds structure in distant galaxies

Detecting normal galaxies at z=3 CO emission now detected in 25 z>2 objects. To date only in luminous AGN and/or gravitationally lensed in 1to 2 days of total obs. time. Normal galaxies are 20 to 30 times fainter. CO emission now detected in 25 z>2 objects. To date only in luminous AGN and/or gravitationally lensed in 1to 2 days of total obs. time. Normal galaxies are 20 to 30 times fainter.

Detecting normal galaxies at z=3 ALMA sensitivity depends on: 1.Atmospheric transparency: Chajnantor plateau at 5000m altitude is superior to all existing mm observatories. 2.Noise performance of receivers: can be reduced by factor 2 (approaching quantum limit). Also gain √2 because ALMA will simultaneously measure both states of polarization. 3.Collecting area: remaining factor of 7 to 10 can only be gained by increasing collecting area to >7000 m 2. ALMA sensitivity depends on: 1.Atmospheric transparency: Chajnantor plateau at 5000m altitude is superior to all existing mm observatories. 2.Noise performance of receivers: can be reduced by factor 2 (approaching quantum limit). Also gain √2 because ALMA will simultaneously measure both states of polarization. 3.Collecting area: remaining factor of 7 to 10 can only be gained by increasing collecting area to >7000 m 2.

At z=3, the 10 kpc molecular disk of the Milky Way will be much smaller than the primary beam → single observation. At z=3, the 10 kpc molecular disk of the Milky Way will be much smaller than the primary beam → single observation. Flux density sensitivity in image from an interferometric array with 2 simultaneously sampled polarizations and 95% quantum efficiency is: Flux density sensitivity in image from an interferometric array with 2 simultaneously sampled polarizations and 95% quantum efficiency is: Aperture efficiencies 0.45<ε a <0.75 Aperture efficiencies 0.45<ε a <0.75 can be achieved (20 µm antenna surface accuracy). can be achieved (20 µm antenna surface accuracy). T sys depends on band, atmosphere, … for 115 GHz, T sys =67 K obtainable. T sys depends on band, atmosphere, … for 115 GHz, T sys =67 K obtainable. At z=3, the 10 kpc molecular disk of the Milky Way will be much smaller than the primary beam → single observation. At z=3, the 10 kpc molecular disk of the Milky Way will be much smaller than the primary beam → single observation. Flux density sensitivity in image from an interferometric array with 2 simultaneously sampled polarizations and 95% quantum efficiency is: Flux density sensitivity in image from an interferometric array with 2 simultaneously sampled polarizations and 95% quantum efficiency is: Aperture efficiencies 0.45<ε a <0.75 Aperture efficiencies 0.45<ε a <0.75 can be achieved (20 µm antenna surface accuracy). can be achieved (20 µm antenna surface accuracy). T sys depends on band, atmosphere, … for 115 GHz, T sys =67 K obtainable. T sys depends on band, atmosphere, … for 115 GHz, T sys =67 K obtainable. Detecting normal galaxies at z=3

Total CO luminosity of Milky Way: L ’ co(1-0) = 3.7x10 8 K km s -1 pc 2 (Solomon & Rivolo 1989). COBE found slightly higher luminosities in higher transitions (Bennett et al 1994) → adopt L ’ co = 5x10 8 K km s -1 pc 2. At z=3 → observe (3-2) or (4-3) transition in the GHz atmospheric band → need to correct, but also higher T CMB providing higher background levels for CO excitation. Different models predict brighter or fainter higher- order transitions. Few measurements of CO rotational transitions exist for distant quasars and ULIRGs, but these are dominated by central regions. → Assume L ’ co(3-2) / L ’ co(1-0) = 1. Total CO luminosity of Milky Way: L ’ co(1-0) = 3.7x10 8 K km s -1 pc 2 (Solomon & Rivolo 1989). COBE found slightly higher luminosities in higher transitions (Bennett et al 1994) → adopt L ’ co = 5x10 8 K km s -1 pc 2. At z=3 → observe (3-2) or (4-3) transition in the GHz atmospheric band → need to correct, but also higher T CMB providing higher background levels for CO excitation. Different models predict brighter or fainter higher- order transitions. Few measurements of CO rotational transitions exist for distant quasars and ULIRGs, but these are dominated by central regions. → Assume L ’ co(3-2) / L ’ co(1-0) = 1.

Detecting normal galaxies at z=3 For ΛCDM cosmology, Δv=300 km/s, the expected peak CO(3-2) flux density is 36 µJy. 5σ detection achievable with ALMA in 12h on source (16h total time) For ΛCDM cosmology, Δv=300 km/s, the expected peak CO(3-2) flux density is 36 µJy. 5σ detection achievable with ALMA in 12h on source (16h total time)

ALMA AS A REDSHIFT MACHINE >50% of the FIR/submm background are submm galaxies. >50% of the FIR/submm background are submm galaxies. Trace heavily obscured star-forming galaxies. Trace heavily obscured star-forming galaxies. Optical/near-IR Optical/near-IR identification very difficult. identification very difficult. Optical spectroscopy: Optical spectroscopy:<z>~2.4. Confirmation needed with CO spectroscopy. Confirmation needed with CO spectroscopy. >50% of the FIR/submm background are submm galaxies. >50% of the FIR/submm background are submm galaxies. Trace heavily obscured star-forming galaxies. Trace heavily obscured star-forming galaxies. Optical/near-IR Optical/near-IR identification very difficult. identification very difficult. Optical spectroscopy: Optical spectroscopy:<z>~2.4. Confirmation needed with CO spectroscopy. Confirmation needed with CO spectroscopy.

SCUBA image of the HDF-N mm continuum contours + HST optical image for the strongest SCUBA source in the HDF-N Hughes et al. 1998Downes et al. 2000

ALMA AS A REDSHIFT MACHINE ALMA will provide 0.1” images of submm sources found in bolometer surveys (LABOCA/APEX, SCUBA-2/JCMT) or with ALMA itself. 3 frequency settings will cover the entire GHz band → at least one CO line. (1h per source) Confirm with observation of high/lower order CO line. (1h per source) ALMA will provide 0.1” images of submm sources found in bolometer surveys (LABOCA/APEX, SCUBA-2/JCMT) or with ALMA itself. 3 frequency settings will cover the entire GHz band → at least one CO line. (1h per source) Confirm with observation of high/lower order CO line. (1h per source)

PHOTOMETRIC REDSHIFTS FROM FLUX RATIOS At z<1, the 1.4 GHz radio to 350 GHz submm flux ratio can provide an estimate of the source redshift (Carilli & Yun 1999) At z<1, the 1.4 GHz radio to 350 GHz submm flux ratio can provide an estimate of the source redshift (Carilli & Yun 1999) NB: valid for SBs. In AGNs radio excess is possible NB: valid for SBs. In AGNs radio excess is possible At higher z, this flux ratio saturates At higher z, this flux ratio saturates  one can use broad band SEDs obtained by observing in different ALMA bands to constrain the position of the redshifted K hot dust peak  one can use broad band SEDs obtained by observing in different ALMA bands to constrain the position of the redshifted K hot dust peak Photometric methods not very accurate for single gals but useful to determine global z distributions At z<1, the 1.4 GHz radio to 350 GHz submm flux ratio can provide an estimate of the source redshift (Carilli & Yun 1999) At z<1, the 1.4 GHz radio to 350 GHz submm flux ratio can provide an estimate of the source redshift (Carilli & Yun 1999) NB: valid for SBs. In AGNs radio excess is possible NB: valid for SBs. In AGNs radio excess is possible At higher z, this flux ratio saturates At higher z, this flux ratio saturates  one can use broad band SEDs obtained by observing in different ALMA bands to constrain the position of the redshifted K hot dust peak  one can use broad band SEDs obtained by observing in different ALMA bands to constrain the position of the redshifted K hot dust peak Photometric methods not very accurate for single gals but useful to determine global z distributions

THE EFFECT OF DUST ON THE STAR FORMATION HISTORY Cosmic SFR density evolution with z show a peak at z = 1.5 – 3 (Blain et al. 2002) BUT effect of dust unknown since current sub-mm obs. limited to most extreme systems at such distances ALMA sensitivities of 10’s of Jy + sufficient resolution ALMA sensitivities of 10’s of µ Jy + sufficient resolution to avoid confusion (plaguing Single Dish obs.)  normal star-forming gals  normal star-forming gals at high z at high z (SFR~10’s of M Sun /yr) (SFR~10’s of M Sun /yr) Cosmic SFR density evolution with z show a peak at z = 1.5 – 3 (Blain et al. 2002) BUT effect of dust unknown since current sub-mm obs. limited to most extreme systems at such distances ALMA sensitivities of 10’s of Jy + sufficient resolution ALMA sensitivities of 10’s of µ Jy + sufficient resolution to avoid confusion (plaguing Single Dish obs.)  normal star-forming gals  normal star-forming gals at high z at high z (SFR~10’s of M Sun /yr) (SFR~10’s of M Sun /yr)

PRECISE MAPPING OF SUB-MM SOURCES Follow-up with ALMA: High resolution CO imaging to determine morphology (mergers?), derive rotation curves → M dyn, density, temperature,... (1h per source) Observe sources in HCN to trace dense regions of star-formation. (10h per source, 20 sources) Total: 12h per source, 170h for sample of 50 sources. Follow-up with ALMA: High resolution CO imaging to determine morphology (mergers?), derive rotation curves → M dyn, density, temperature,... (1h per source) Observe sources in HCN to trace dense regions of star-formation. (10h per source, 20 sources) Total: 12h per source, 170h for sample of 50 sources.

M51 Galaxy (Whirlpool, NGC5195) Located at a distance of 37 million light-years from us, the famous M51 Galaxy (Sc type) was discovered in 1773 by Charles Messier. Due to its orientation in space, it is seen "face-on". Optical image of M51. Left : Continuum emission at 1.3 mm from the cold dust (<20K) contained in the spiral arms of M51 as observed with the 30m telescope. The pixel size in both images is 12 arc seconds. The continuum emission of cold dust closely follows the spiral pattern traced by the CO emission and correlates poorly with the emission from neutral hydrogen HI clouds. Similar results have been obtained by mapping the "edge-on" galaxy NGC 891, where the dust correlates well with the CO emission up to a radius of 25 thousand light-years from the center of the galaxy. Right: Map of the CO(2-1) emission from M51.

Obscured galaxyformation: low redshift (Meier & Turner 2004) Obscured galaxy formation: low redshift (Meier & Turner 2004) IC342  distance = 2 Mpc  M _gas = 4e7 M _sun  SFR = 0.1 M _sun /yr  Starburst age = 1e7 yrs IC342  distance = 2 Mpc  M _gas = 4e7 M _sun  SFR = 0.1 M _sun /yr  Starburst age = 1e7 yrs 30” = 300pc colors  OPTICAL Grey contours  CO(1-0) White contours  mm continuum

Nearby star forming Galaxies – Chemistry/Physics: IC342, D=2Mpc CO: all gas HC3N: Dense C2H: PDRs ALMA: Image with GMC resolution (50pc) to 250 Mpc  Rich clusters: Virgo = 16 Mpc, Coma = 100 Mpc  ULIRGs: Arp 220 = 75 Mpc, Mrk 273 = 160 Mpc ALMA: Image with GMC resolution (50pc) to 250 Mpc  Rich clusters: Virgo = 16 Mpc, Coma = 100 Mpc  ULIRGs: Arp 220 = 75 Mpc, Mrk 273 = 160 Mpc 300pc Meier & Turner 2004

Nearby Gals II: Dynamics: ‘feeding the nucleus’ – NGC6946, D=5.5Mpc 100 pc PdBI 0.5” CO(2-1) - Gas Lanes along Bar - Streaming Motions - Gas Disk w/ R <15pc ALMA: extend to Mrk 231 at 180 Mpc Cygnus A at 240 Mpc PdBI 0.5” CO(2-1) - Gas Lanes along Bar - Streaming Motions - Gas Disk w/ R <15pc ALMA: extend to Mrk 231 at 180 Mpc Cygnus A at 240 Mpc Schinnerer et al., in prep.

– – Detected sources not associated with cluster galaxies. – – Associated with mJy radio sources (VLA) – – Mostly dusty star forming galaxies at median redshift but also possible that heating sources are AGN   MAMBO survey of the cluster A2125 (Carilli et al. 2001) at 250 GHz Disentangling Nuclear Starbursts from AGNs

Optically identified submm detected sources (only three so far) Two of them have large molecular gas masses (seen through CO emission) z = 2.81 z = 2.56 Dust continuumCO(3-2) emission (Frayer & Scoville 1999) AGN Type II Starburst 0.1” res.  ~1 kpc at z~1 0.01” res.  ~1 kpc at z~3

Precise 0.1” resolution images 0.1” resolution needed to complement contemporary facilities: JWST, eVLA, AO with 8-10m telescopes, … High angular resolution and sensitivity complementary. High fidelity images require a sufficiently large number of baselines to fill >50% of the uv-plane. Short tracking (<2 hours) to reduce atmospheric variations → requires ND > 560 for a maximum baseline of 3 km. Achievable with 64 12m antennas. 0.1” resolution needed to complement contemporary facilities: JWST, eVLA, AO with 8-10m telescopes, … High angular resolution and sensitivity complementary. High fidelity images require a sufficiently large number of baselines to fill >50% of the uv-plane. Short tracking (<2 hours) to reduce atmospheric variations → requires ND > 560 for a maximum baseline of 3 km. Achievable with 64 12m antennas.

Precise 0.1” resolution images Array cannot measure smallest spatial frequencies (<D). Solve by having four antennas optimized for total power measurements (nutating secondaries). Remaining gap in uv-plane filled in by Atacama Compact Array (ACA): 12 antennas 7m diameter. Array cannot measure smallest spatial frequencies (<D). Solve by having four antennas optimized for total power measurements (nutating secondaries). Remaining gap in uv-plane filled in by Atacama Compact Array (ACA): 12 antennas 7m diameter.

L_FIR vs L’(CO) (Beelen + 04) Index=1.7 Index= M  10 3 M  /yr ALMA z>2 PdBI/Carma z>2

Enabling technology III: Wideband spectroscopy – Redshifts for obscured/faint sources: GHz spectrometers on ALMA, LMT, GBT (Min Yun 04, Harris 04) L FIR = L  ALMA

Power of IR Classification: Edge-on Spiral NGC 5746 Spitzer/IRAC  m Optical gri 2MASS JHK Jarrett et al (AJ, 125, 525)Frei al (AJ, 111, 174) Prominent dust lane in optical (and even near-IR) prevents unambiguous classification IR images demonstrate class "Sab" with ring Star formation concentrated along ring and outside it Prominent dust lane in optical (and even near-IR) prevents unambiguous classification IR images demonstrate class "Sab" with ring Star formation concentrated along ring and outside it

NGC Centaurus A Visible image IRAC image Keene et al. 2004