Transcript DESpec survey strategy : realistic mock catalogue and target selection Stephanie Jouvel, Filipe Abdalla, Huan Lin, James Annis, Richard Kron 22 jun 2011

DESpec survey strategy :
realistic mock catalogue
and target selection
Stephanie Jouvel, Filipe Abdalla, Huan Lin, James
Annis, Richard Kron
22 jun 2011
PLAN : Investigate DESpec survey strategy
• Build realistic Mock Catalogues of the DES +
VISTA survey
• Derive spectrograph/fibers sensitivities for
ground-based observation
• Investigate redshift distribution and galaxy
density for DESpec science
• Which tragetting strategy ? What criterion in
photoz or color-color space ?
Galaxy Properties from Deep Surveys
the COSMOS survey
Koekemoer et al. 2007
•
•
•
•
2deg2 (representative)
30 photometric bands
from UV to IR with HST,
Galex, Spitzer, Subaru,
VLA, NOAO
HST/ACS I band
observation: galaxy
sizes & shapes
zCosmos spectroscopic
survey
the VVDS “Deep” survey
Le fèvre et al. 2005
•
VIMOS/VLT deep
spectroscopic survey on
~0.5 sq.deg
•
~9000 spectra from 0<z<5
down to IAB ~24
(magnitude selected)
3
Building Mock Catalogues
Use this catalogue
COSMOS Mock catalogue
GOODS Luminosity Function
catalogue
COSMOS catalogue
(position, size, photometry)
1 million galaxies
Simulated Catalogue
based on GOODS LF(z,type)
GOODS LF from
Dahlen et al. 2005
Jouvel et al. 2009
Photoz, SED, emission lines
COSMOS size distribution,
emission lines
- Realistic redshift
distribution,
- Realistic size
distribution,
- Emission line fluxes
catalogue
Photometry in DE mission filter sets
+ Photometric errors
DE Forecast
Stephanie Jouvel
COSMOS photoz from
Ilbert et al. 2009
Jouvel et al 2010
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COSMOS Mock Catalog (CMC)
Construction using the properties of the COSMOS-ACS WL catalog
using :
- realistic photometric redshift distribution
30 photometric bands
calibrated with spectroscopic redshift :
> zCOSMOS bright (I~22 AB)
> zCOSMOS faint (I~25 AB)
> MIPS-spectro-z sample
- best-fit template from this photoz distribution
- galaxy size measured by Sextractor from Leauthaud et al 2007
Validation of the CMC using :
- GOODS N&S visible
- UDF visible + jh band
- VVDS Ks band + spectro-z
- GOODS-MUSIC Ks band
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COSMOS Mock
Catalogue(CMC)
We want precision cosmology
 Need for realistic mock
catalogues to test photoz codes :
- Realistic redshift distribution
Impacts DE FoM from WL
- Realistic distribution of galaxy
sizes in redshift and magnitude
=> Realistic noise distribution
impact photoz results
-Emission line catalogue
Create spectroscopic catalogue
to study photoz calibration
Stephanie Jouvel
6
COSMOS Mock Catalog (CMC) :
Validation
Emission line prediction :
Kennicutt et al. 1998 :
UV-OII relation
log[OII ] = 0.4MUV +10.57
DM z 
2.5
Validation of the redshift
distribution and emission line
fluxes using the VVDS-DEEP
I~24 AB (Lamareille et al 2008)
Jouvel et al. 2009
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Spectroscopic Success Rate (SSR) :
Validation using VVDS
SSR : galaxy rate
for which we will be
able to measure a
redshift
Validation :
reproducing
the VVDS SSR
Jouvel et al. 2009
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PhotoZ Calibration Survey (PZCS):
Spectroscopic Success Rate (SSR)
In the context of the
JDEM survey we
simulated different
spectroscopic surveys :
WIDE NIR
photometric
calibration
(BAO–RD survey)
template
calibration:
- DEEP-visible-NIR
- DEEP-NIR
Jouvel et al. 2009
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SSR Forecast for PZCS
Forecast :
-DEEP-NIR
space survey
(PZCS)
DEEP-NIR :
I~27 0.5<z<3.5
35gal/arcmin2
Jouvel et al. 2009
10
SSR forecast for PZCS
Forecast :
DEEP-visible-NIR
space survey
(PZCS)
DEEP-vis-NIR :
I~27 0<z<3.5
60gal/arcmin2
Jouvel et al. 2009
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SSR Forecast for PZCS
Forecast :
WIDE-NIR space
survey (BAO like)
WIDE-NIR :
H ~22 0.5<z<1.5
5gal/arcmin2
Jouvel et al. 2009
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DESpec survey strategy :
1. Mock catalogue and
photoz
DES+VISTA photometric redshift
ANNz training
with 10000
galaxies
Le Phare with
COSMOS
templates
DESpec survey strategy :
2. Target selection
Line sensitivities from Huan Lin
- Sensitivities for
30 mins exposure
time on 2 arcsec ø
fibers (70% light
fraction)
- Resolution
R=2500 at 0.9um.
- Calculation
include DES
throughput + sky
noise and
atmospheric lines
from Hanuschik
(2003)
Redshift distribution from em lines
Redshift distribution of
emission line galaxies
selected with :
- I (DES) < 23
- 1 < photoz < 2
- at least one em line
detected at 5 sigma
Photoz with Le Phare
(template fitting
method) u DES+VISTA
Can we select the
emission line galaxies
based on DES+VISTA
photometry only ?
Total of roughly
12000 gal/deg2
Multidimensional method based on
NN selection
Use of NN to select em line galaxies
We assign a value of :
- 1 for targetted em
line galaxies
- 0 for non targetted
galaxies
We then use ANNz and
train a NN on a sample
of 10000 galaxies from
the CMC (DES+VISTA)
Results for i(DES) < 24
Which ANNz selection criterion ?
Fig : Cumulated nbr
galaxies/deg2 fct ANNz
target probability
We suggest a selection
criterion of 0.8 yielding
to :
-7500 emission line
galaxies / deg2 i(DES)<24
- and a contamination of
800 gal/deg2 i(DES)<24
0.8
Which ANNz selection criterion ?
Solid : percentage of
galaxies for which we will
measure a redshift/total
nbr gal & Dashed : SSR
fct ANNz target
probability
We suggest a selection
criterion of 0.8 yielding
to :
-7500 emission line
galaxies / deg2 i(DES)<24
- and a contamination of
800 gal/deg2 i(DES)<24
Redshift distribution of ANNz sel 0.8
Redshift distribution / em lines gal
Redshift distribution / em lines gal
Redshift distribution / em lines gal
Line sensitivities from Huan Lin 0.6-1um
- Sensitivities for
30 mins exposure
time on 2 arcsec ø
fibers (70% light
fraction)
- Resolution
R=2500 at 0.9um.
- Calculation
include DES
throughput + sky
noise and
atmospheric lines
from Hanuschik
(2003)
Use of NN to select em line galaxies
We assign a value of :
- 1 for targetted em
line galaxies
- 0 for non targetted
galaxies
We then use ANNz and
train a NN on a sample
of 10000 galaxies from
the CMC (DES+VISTA)
Results for i(DES) < 24
Using Huan Lin
sensitivities cut between
0.6-1um
Which ANNz selection criterion ?
Fig : Cumulated nbr
galaxies/deg2 fct ANNz
target probability
We suggest a selection
criterion of 0.8 yielding
to :
-7500 emission line
galaxies / deg2 i(DES)<24
- and a contamination of
800 gal/deg2 i(DES)<24
Using Huan Lin
sensitivities cut between
0.6-1um
0.8
Which ANNz selection criterion ?
Solid : percentage of
galaxies for which we will
measure a redshift/total
nbr gal & Dashed : SSR
fct ANNz target
probability
We suggest a selection
criterion of 0.8 yielding
to :
-7500 emission line
galaxies / deg2 i(DES)<24
- and a contamination of
800 gal/deg2 i(DES)<24
Using Huan Lin
sensitivities cut between
0.6-1um
Redshift distribution of ANNz sel 0.8
Using Huan Lin
sensitivities cut between
0.6-1um
Photoz for the NN target galaxies
Can we do color-color cut ?
g-r vs r-i
r-i vs i-z
It looks difficult to select the OII line in a coloc-color cut. We need a
higher dimensional kind of cut such as photoz codes can provide
Conclusion
• We simulated a DES+VISTA catalogue using the
CMC which include emission line fluxes.
• Huan Lin derived a fiber sensitivities including all
instruments troughput and sky noise including
astmospheric lines for a DESpec instrument.
• Using Huan Lin sensitivities we can select
emission line galaxies from DES+VISTA
photometry using ANNz.
• We suggest a selection criterion of 0.8 with a
yield of 8000gal/deg2 for i(DES)<24 and a success
rate of 93% or 5000gal/deg2 i(DES)<23 and a
success rate of 95% (to verify).
• A color-color cut does not seem the optimal
solution to select target for DESpec.
COSMOS Mock Catalog (CMC):
Validation
Jouvel et al. 2009
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COSMOS Mock
Catalogue(CMC)
We want precision cosmology
 Need for realistic mock
catalogues to test photoz codes :
- Realistic redshift distribution
Impacts DE FoM from WL
- Realistic distribution of galaxy
sizes in redshift and magnitude
=> Realistic noise distribution
impact photoz results
-Emission line catalogue
Create spectroscopic catalogue
to study photoz calibration
Stephanie Jouvel
35
Emission lines
• z=0
H-a
6563 A
Ly-a 1215 A
OII
3726-3729 A doublet
H-b
4861 A
OIII
4959A and 5007A
• z~2.5 : Ly-a 4250 OII 13000
• z~3.5 : Ly-a 5460
Results from CMC : Photoz calibration
work with Gary Bernstein
as part of the SNAP-WL group
-
Simulation of spectroscopic
survey using forecast survey
sensitivities for : optical/+NIR
surveys, SHALLOW or DEEP.
=> No photoz calibration possible for
z<0.5 & z>1.6 galaxies.
=> Need of visible + NIR
spectroscopy to cover the whole
redshift range of future
photometric surveys.
Stephanie Jouvel
Jouvel et al. 2009
37
Photoz : Need for spectroscopic calibration
Successful method to remove systematic trends
u* +0.019
g’ -0.079
r’ -0.002
i’ 0
Z’ -0.008
Importance of the zero-point calibration
Ilbert et al.2006
Further improvement of the templates