COSMOS: An Overview
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Scientific aims
Scheduling
Field selection
Ground-based Observations
COSMOS -- 2 deg2 field image w/ ACS
640 (590) orbits : 2100 sec 814W-I per field (4 exposures)
=> IAB= 27.2 (10s )
L* galaxy has I = 26 at z = 2
Evolution of galaxies, AGN and dark matter
as function of large-scale structure and redshift (z = 0.5 -- 4)
Major features :
• large area -- 9xGEMS
=> cover largest large scale structures
• high sensitivity ( I > 27 mag, 10s)
=> morphology of L* galaxies at z < 2
• sensitivity + area
=> 106 galaxies , unusual objects at higher z
• equatorial => multi-l observations from all tel.
• assembly of galaxies, clusters and dark matter on scales
up 1014 Msun -- well-sampled w/ redshift
• evolution of galaxy morpholgy, merging and star formation
as functions of LSS environment and redshift
• reconstruction of dark matter distribution and properties
out to z > 1
• evolution of AGN and the relationship between black hole
growth and galaxy evolution
Numerous past investigations of :
LF (z)
SFR (z)
morphology (z)
but studying evolution w/o LSS context !!
Merging and interactions driven evolution
cosmos
Prob. of mass structures
as func. of field size
Dz = 0.02 => 80 Mpc depth
to avoid cosmic var. => image > 10
Frenk et.al. 02
COSMOS field :
a2000= 10:00:28.6
d2000= +02:12:21
• accessible to all grd-based tel. (ALMA, VLT, Keck, …)
• VLT-VIMOS : 100,000 opt. spectra here
• complete ancillary datasets (x-ray, opt, IR , FIR, radio)
Field covers :
z = 0.5 50 x 50 Mpc (comoving)
2 137 x 137 Mpc
3 170 x 170 Mpc
6 x 107 Mpc3 out to z = 3
cosmos
cosmos
< 100mm>
0.85 MJy/sr
fi The ‘final’ field for extragalactic evolution surveys
at z = 0.5 to 4
Accesible to all telescopes
=> single orbit I-band is sufficient for
morphology at z = 0.2 -- 2
single orbit 814I gives 1/2 sensitivity of 5 orbits z (GOODS)
Progress so far (Good News)
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320 HST orbits completed with the data reduced
Parallel NICMOS (NIC3) and WFPC2 (UV) (completed)
BVRiz band deep imaging by Subaru (10 nights)
K-band imaging at Kitt Peak and CTIO completed (10N)
Deep K-band imaging by CFHT (Completed)
NUV and FUV observations by GALEX completed
U-band imaging by CFHT (completed)
XMM observations (completed)
Time awarded on UKIRT Wide Field Camera (10N)
VLT spectroscopy for 100,000 galaxies (in progress)
VLA radio (1.4 GHz) survey time awarded (200 hours)
20 Nights of observing time on Subaru is applied for
Progress so far (Bad News)
• No HST time awarded for g-band
• No Spitzer time awarded
Lensing and Dark Matter :
ACS psf => ~ 60 gal. / arcmin2
=> 3 times better SNR than grd-based imaging
clusters and groups picked out from XMM deep imaging
compare DM mass estimates w/
• dynamical from spectroscopic velocities
• photometric masses
=> bias as function of morph. , cluster richness, and z
(predict : shear µ z1.4 for 1 -- 30 arcmin)
also, expect ~ 100 new strong lenses
noiseless mass map
grd-based reconstruction
acs- cosmos
w/ acs psf, snr 3 times better
60 arcmin
variance of shear as fn.
of scale for :
• Grd-based
• WFPC2
• ACS-COSMOS
cosmos
mass fraction
Halo mass growth w/ z
Mhalo
40 co-I’s
ACS data Make use of GOODS pipeline
HST imaging started in October (cycle 12 & 13)
Galex starts in Dec/Jan
Subaru imaging starts in Jan 04
VIMOS spectroscopy (hopefully) in Mar/Apr 04
XMM in 03/04
SIRTF (hopefully in first GO cycle)
Everyone here realizes the need for LSS context, large area
and multi-l !
COSMOS will be a fundamental public resource for cosmology
COSMOS - VLA Data
vla-a: 10 hr
7 pointings
rms ~ 25 mJy/beam
beam ~ 1.9” x 1.6”
Schinnerer, Carilli, Scoville et al.
An anology :
Imaging NYC (~5 miles) w/
4096 x 4096 camera
mosaic 640 images => 25 x 25 fields
fi102,000 x 102,000 image
fi 4 inch resolution
could see every one of 10 million people ,
resolve each => size, shape, clothing
w/i COSMOS field, should see 2 million galaxies ,
ACS resolution => size, multiplicity, age
environment, clustering
ellipticals -- chubby , balding, not too lively
spirals -- young , upwardly mobile
the E’s ate too much, early in life, sat around in the
most crowded corners , eating unhealthy fast food
the spirals hung out in the sparse, dark outer reaches of the
city, ate lots of ruffage, didn’t gorge themselves
Anyway …