High Redshift Galaxies/Galaxy Surveys
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Transcript of High Redshift Galaxies/Galaxy Surveys
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High Redshift Galaxies/Galaxy Surveys
ALMA Community Day April 18, 2011
Neal A. MillerUniversity of Maryland
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ALMA Community Day, STScI 2
Overview• ALMA as IFU
– Imaging (continuum) and spectroscopy (line) rolled into one
• Up to 8GHz bandwidth per polarization, small channels
– Talk arranged continuum then line• General Topics
– SFH of universe• General birth/building of galaxies• Galaxies in the epoch of reionization
– Co-evolution of bulges and black holesApril 18, 2011
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ALMA Community Day, STScI 3
Linear Resolution
April 18, 2011
Rough rules of thumb
Compact Array: ~5 to 35 kpc resolution Most sources unresolved spatially
Extended Array: ~50 pc to 350 pc Angular resolutions a few times better than HST
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ALMA Community Day, STScI 4
Continuum: Negative K Correction
April 18, 2011
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ALMA Community Day, STScI 5
Negative K Correction in Play
April 18, 2011
c Lanzetta
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ALMA Community Day, STScI 6
Continuum: Early Science Possibilities
Mosaic observations of significant fields?Tradeoffs:
• Intrinsic flux of sources greater at higher frequencies
• Field of view is smaller at higher frequencies (about 1’ at Band 3, under 10” at Band 9)
• Receiver temperatures higher at higher frequencies
April 18, 2011
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ALMA Community Day, STScI 7
ALMA: Imaging the HUDF
April 18, 2011
Band 3: 100 GHz ~23 pointings to mosaicfull 2.2’ square of HUDF
Arp 220 sources about3 μJy flux density
4.7 μJy per pointing, a 3σdetection requires 1.6 μJyrms
Over 12 days per pointing!Not enough time in Early Science
Full Array: still over a dayper pointing
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ALMA Community Day, STScI 8
ALMA: Imaging the HUDF
April 18, 2011
Band 6: 240 GHz ~115 pointings to mosaicFull 2.2’ square of HUDF(too many for Early Science)
Arp 220 sources about30 μJy flux density
47 μJy per pointing, a 3σDetection requires 16 μJy rms
6.9 hr per pointing in Early Science (not enoughtime in Early Science)
Full Array: ~100 hoursTotal with overheads
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ALMA Community Day, STScI 9
Continuum Science• Contiguous area survey observations of deep
fields not well suited for Early Science, good for Full Array
• Surveys to follow-up individual sources are more appealing– SCUBA, AzTEC, LABOCA, etc.– SMGs, QSOs, HzRG with flux densities of a few
mJy– Band 6 or 7 (800μm to 1.4mm)
• Band 7 to reach 0.2 mJy just 9 minutes Early Science• Resolutions of ~1” to ~0.01” (10 kpc to 100 pc)
April 18, 2011
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ALMA Community Day, STScI 10
Individual Source Continuum Surveys
• Better positions– Single dish observations with bolometer arrays,
tens of arcseconds resolution• Prior follow-up was radio, expensive time requirement
• FIR luminosities through SED fitting– Pair with non-RJ data (Spitzer, Herschel)– SFR in absence of AGN– Dust temperatures, masses
• Other sources – GRBs?
April 18, 2011
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ALMA Community Day, STScI 11
Spectral Line: CO
April 18, 2011
CO(J=1-0) traces totalmolecular gas mass
Higher J for warmer, densergas
Ratios give excitation properties of molecular gas
Line widths for estimate ofdynamical mass
CO correlates with FIR, hence rough SFR
Also for SF efficiency: FIRfor current SF, CO for gasreservoir
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ALMA Community Day, STScI 12
CO Rotational Ladders
April 18, 2011
Figure from Weiss et al (2007)
Sources: Central regions of local starbursts (NGC253, M82)
SMGs (SMM16359, highly lensed)
QSOs (BR1202, SDSS J1148 at z=6.4)
BAL QSO (APM0827)
Strength: Peak flux densities of several mJy, integrated lines of a few Jy km/s
Widths of a few hundred km/s
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ALMA Community Day, STScI 13
Spectral Line: Additional Lines
April 18, 2011
HCN only from dense gas,stronger indicator of starformation
HCN line luminosities muchhigher in SMGs and relatedobjects than in normal spirals
[CII] strongest atomic line, cooling line for atomic gas
Also [CI]; similar critical density for excitation as CO
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ALMA Community Day, STScI 14
Spectral Line Possibilities• Redshift search for SMGs
– Difficult to get optical (position, dust obscuration)– Look for CO lines, get 8 GHz per polarization to
cover full bands in multiple observations– Line spacing as 1/(1+z)
• Absorption lines• CO in host of object types
– High z quasars– Lensed “normal” galaxies– LAEs, LBGs?
April 18, 2011
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ALMA Community Day, STScI 15
Possible Questions• Black hole mass from HST, dynamical mass
from CO?• SF efficiency? Pair FIR with line luminosity• Morphology – big disks or mergers for
SMGs?– Formation of present day massive ellipticals?
• AGN unification and evolutionary models?– Starburst to obscured AGN to unobscured AGN?
April 18, 2011