Science and strategy with PFS

Brice MénardICRR, Tokyo University
Johns Hopkins University
Canadian Institute for Theoretical Astrophysics

PFS has unique characteristics. One should make use of them todo things in new and unique ways.
PFS can observe more galaxies and go deeper than current surveys.
The real question is: can we learn something new?
Can PSF be used for a new type of measurement?

We should see how it can do things differently.

Question: What is the best merit of such a survey?

Survey parameters

wavelength range
Survey = F ( resolution,number of fibers

Fixedarea
number of nights , depth, ... )samplingof order ~100

to be discussed

Survey parameters

Survey parameters• PFS wide:

300 deg2m = 23
1 million galaxies• PFS deep:

30 deg2
m = 24250,000 galaxies

Survey parameters?

• PFS wide:

300 deg2m = 23
1 million galaxies• PFS deep:

30 deg2
m = 24250,000 galaxies

Survey parameters• PFS wide:

300 deg2m = 23
1 million galaxies• PFS deep:

30 deg2
m = 24250,000 galaxies

Object-based analyses
The figure of merit ~ Ngal
PFS is not in the best position for:- finding rare objects- spatial one-point statistics- stacking spectra in source restframeSpatial analyses
The figure of merit is then ~ Npairs which goes like Ngal2 / Area

wavelength range
Survey = F ( resolution,
number of fibers

area
number of nights , depth, ... )sampling

2dF, 6dF, SDSS, BOSS, BigBOSS have sampling limitations due tofiber collision: no sampling on scales smaller than ~1 arcmin
this is the galaxy-halo regime
Zehavi et al.

Masaki et al.

A galaxy haloSpatial analyses in the 1-halo regime

Spatial analyses in the 1-halo regime• PFS wide / 2 visits:
300 =>150 deg2
m = 23
1 million galaxies

Spatial analyses in the 1-halo regime

Question: What is the best merit of such a survey?

Most of the science is based on the detection of emission lines.
Goal: 2D survey => 3D
5000 pixels => 1 number: redshift
In addition, we get metallicities, SFR, etc.

5000 pixels => a few numbers.
Can we extract more information?

Question: What is the best merit of such a survey?

Question: Can we extract more than a few numbers from the spectra?

Question: What is the best merit of such a survey?
Question: Can we extract more than a few numbers from the spectra?

Statistical absorption:a new window on the distribution of baryons

Absorption line
spectroscopy

Steidel et al. (1997)

The sensitivity is proportional to Npairs

Spatial analyses in the 1-halo regime• PFS wide / 2 visits:
300 =>150 deg2
m = 23
1 million galaxies

Statistical absorption in 0-D

Steidel et al. (2010)

Composite spectra of galaxies: no spatial information

Statistical absorption in 1-DSteidel et al. (2010)

Based only on ~500 pairs.

PFS will have ~ 1,000,000.

(Ménard et al, 2009)(Sheldon et al, 2004)

mass profile fromstatistical lensing(galaxy-galaxy lensing)gas profile fromstatistical absorption

Statistical analyses & composite spectraYork et al. (2005)

Statistical absorption• Absorption lines can be found over the entire redshift range
probed by PFS• Statistical absorption extracts information from virtually allpixels.

• It will open a new window on the spatial distribution of gas inthe Universe. 0D => 1,2D• Absorption lines carry information on gas Temperature,Metallicity, abundances, column density, velocity dispersion, dust
depletion, etc. There is a lot of physics.

Statistical emission/absorption
Ménard et al. (2009)

Statistical detection of OII emission at z=1
from unrelated SDSS QSO spectra

No stellar continuum detected!
The cross-correlation with absorbers along
the line of sight allows us to detect emission
lines statistically.

This demonstrates that statistical absorption
is feasible. The only requirement is a large
Npairs.

Conclusion• One of PFS’ strengths is measuring spatial
correlations (~Npairs) in the 1-halo regime• Statistical absorption is a unique opportunity for PFS. It is basedon Npairs and extract information from all the pixels of all spectra.

• I think it will be go through a history similar to weak lensing overthe past decade.

• We will be able to measure gas column density, metallicity,temperature, abundances, dust depletion, etc... as a function of scale.
It will provide us with a mapping of baryons in the Universe
This is just one example. The PFS dataset will be a great opportunity
for the Japanese community. Many unique projects for students.