high redshift galaxies/galaxy surveys
DESCRIPTION
High Redshift Galaxies/Galaxy Surveys. ALMA Community Day April 18, 2011 Neal A. Miller University of Maryland. Overview. ALMA as IFU Imaging (continuum) and spectroscopy (line) rolled into one Up to 8GHz bandwidth per polarization, small channels - PowerPoint PPT PresentationTRANSCRIPT
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
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
ALMA Community Day, STScI 4
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
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
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
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
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