High Redshift Galaxies/Galaxy Surveys

ALMA Community Day April 18, 2011

Neal A. MillerUniversity of Maryland

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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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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Continuum: Negative K Correction

April 18, 2011

ALMA Community Day, STScI 5

Negative K Correction in Play

April 18, 2011

c Lanzetta

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

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

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

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

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

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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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

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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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

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