Diapositive 1

Report
FRESNEL Imager:
Extragalactic Science in
the UV-Optical domains
Roser Pelló
Laboratoire d’Astrophysique de Toulouse-Tarbes
FRENEL Meeting, Nice, 23-25 September 2009
FI and extragalactic studies

Spatial resolution

Wavelength coverage (100nm to 10 microns)

High dynamic range
FI ...
starts operations after JWST, ALMA and possibly SKA, ...
it is intended to be a follow up rather than a survey facility
could be efficiently used to target galaxies selected from utradeep photometric and spectroscopic surveys
 Mapping the Star Formation of galaxies, from the local
universe to ~75% look back time (UV, z~0 to 2)
 Constraining the physical properties of the first galaxies (IR)
Extragalactic studies in the UV
GALEX FUV
GALEX NUV

Galaxy
Evolution
Explorer
(GALEX,
2003-)
Ex.: composite
spectra of high-z
galaxies observed
in the optical
domain
(VVDS Survey
Le Fevre et al. 06,
Paltani et al. 07)
Composite spectra of
z~3 LBGs, for different
Ly a equivalent widths,
observed in the optical
(lambda~4500-7000 A)
(Shapley et al. 2003)
Line diagnostics and redshift
Ha + [NII]
Hb + [OIII]5007 [OII]3727
near-IR
HeII 1640
Ly a
visible
Line diagnostics and redshift
Line diagnostics shift towards the near-IR (lambda>1 micron)
AGN
Empirical
discrimination
between
AGN/starbursts
From Erb et al. 06
Starbursts
Ha/[NII]
[S II]
87 combined spectra of galaxies at
z~2 (~14-15 specta/ mass bin)
Star-formation rate determinations

Different
calibrations
available :
 UV
continuum
flux
 FIR emission
 H alpha
 [OII]3727
 (Ly alpha)
Based on the
properties of the
integrated
population
(Kennicutt 1998, Schaerer 1999, ...)
Groves 2005
Star-formation rate determinations
(from Schaerer 1999)
L(Ha) luminosity
IMF
UV continuum flux density
Cosmic SFR density

Inhomogneous SFR
indicators at different
redshifts
• H alpha z< 0.5
• [OII]3727 0.5<z<1.5
• continuum UV z > 1.5
Lilly et al. 96
Connolly et al. 97
Madau et al. 96
Steidel et al. 99
Old paper by Steidel et al. 1999...
Cosmic SFR density

Inhomogneous SFR
indicators at different
redshifts
• H alpha z< 0.5
• [OII]3727 0.5<z<1.5
• continuum UV z > 1.5
Lilly et al. 96
Connolly et al. 97
Madau et al. 96
Steidel et al. 99
Bouwens et al. 2008
D'apres Schiminovich et al. 05
HDF
GALEX
Dust extinction correction is an
issue...
GALEX
Calibration in the local universe
Extragalactic studies in the UV with FI

UV (restframe) observations ==> Star Formation
activity

UV-calibrated Star Formation Rate measurements

Lyman alpha properties

Metal abundances

Extinction

UV (SF) – morphology

Recent (age<~ 100 Myr) SF history
A complete view of star-formation at 0<z<2
(75% of light travel time... )
Ly alpha emission
HST/STIS
4''
IZw18
A complex Ly a emission in a
Local sturburst (Atek et al. 09)
Ly alpha emission
- Empirical estimate of Ly a
escape fraction in a statistically
significant sample of z~0-0.3 Lya
emitters detected by GALEX (24
galaxies)
Atek et al. 2009
A complex Ly a emission in a
Local sturburst (Atek et al. 09)
The size of local starburst galaxies
•- Emission-line images of local
starbursts (Ha, [OIII] and Hb).
•- Comparison between Lya, Ha
and UV continuum emission
15''x15''
15''x15''
5''x5''
7.5''x7.5''
Ly a emission
From Ostlin et al. 08
15''x15''
Ly alpha/UV emission in distant galaxies
Lemoine-Busserolle et al. 2003
Pello et al. 2003
Lensed galaxies :
Z = 2.5
1.7
2.7
Local starbursts
AC114-S2
AC114-S2
AC114-S2
Le Borgne et al.
SED fitting to constrain SFR history,
age of stellar population, E(B-V),
metallicity
Ly alpha/UV emission in distant galaxies
Le Borgne et al.
SED fitting to constrain SFR
history, age of stellar population,
E(B-V), metallicity
U
B
extinction corrected SED
V
R
Metallicity constraints
from UV slope β
I
J
z~1.7 lensed galaxy
K
Ly alpha emission in distant galaxies
Ex.: Schaerer & Verhamme 08, modeling Lyman alpha line in
Ms1512 – cB58 (lensed LBG, z~2.7)
The size of high-z star-forming galaxies
~L* galaxies
From Bouwens & Illingworth 09
The size of high-z star-forming galaxies
3 arcsec
Z~6
dropouts
in the
HUDF
From Bouwens & Illingworth 09
The size of high-z star-forming galaxies
Z~2.7-3.7 Ly
a emitters
2D spectra
Lambda
~5000 A
15 arcsec
40 A
From Rauch et al. 08
1 arcsec
galaxies
0.1 arcsec
0.01 arcsec
0.001 arcsec
1 arcsec
galaxies
0.1 arcsec
bulges
Spiral arms
Globular
clusters
0.01 arcsec
HII regions
0.001 arcsec
Paladini et al. 04
Urry & Padovani, (1995)
NB region
(Teff ~ 60K)
Jets
θ
BH
BL region
(Teff~ 2000 K, ~0.1-0.01 pc)
Obscuring torus
(200-800K, ~1-300 pc)
Accretion disk
(Teff ~ 105 K, ~0.01 pc)
1 arcsec
galaxies
bulges
Spiral arms
0.1 arcsec
Globular
clusters
0.01 arcsec
HII regions
AGN
obscuring torus
AGN
accretion disk (~0.01 pc)
0.001 arcsec
Conclusions (I)

FI should be able to yield a HR UV (restframe) picture of the local
universe. Study of photoionization regions: structure (high dynamics),
physics (line diagnostics -stellar, ISM-, stellar populations, ...).
 UV-calibrated Star Formation Rate measurements

UV-calibrated indicators for extragalactic physics in the distant
universe (metallicity, age of underlying stellar populations,
IMF?, ...)

Lyman alpha properties in local starbursts. Scape fraction as a
function of relevant parameters ==> High-z universe

Unprecedented capability in understanding star-formation
processes at HII-region's scale.

Understanding co-evolution AGN <===> host galaxy. Nuclear
regions of galaxies: looking for AGN signatures in the core
region, constraining AGN feedback ...
Conclusions (II)

Depending on sensitivity, FI could provide the UV budget of star
formation in galaxies from z~0 to z~2 (universe aged of 3.342 Gyr).
 Understanding the downsizing mechanism at the spatial scale
corresponding to a typical HII region up to z~2, and a well
suited FOV(ex. FOV(z~1-2)~ is ~70 kpc; FOV(z~0.5)~50 kpc,
and ~32 kpc at z~0.3).

Lyman alpha emission in details: mechanism and geometry of
SF activity

Metallicity evolution for different galaxy environments.

Other interesting cases requiring high dynamic range: multipleimaged QSOs (FVO~1-3''); clusters of galaxies (cluster core, AGN
feedback, FVO~1-10'').

Tentative topic: looking at new-born galaxies at all z. This means
looking for PopIII signatures (e.g. HeII1640 line) in (compact/ small/
BCGs) galaxies.
Open questions:
The band-pass is relatively narrow (e.g. ~70A in the UV and ~450A
in the near-IR at ~8000A in the imaging mode):
==> Sensitivity issue in the continuum detection (usual BB filters are
~5-10 larger in the UV)
==> For a given configuration, and for a given spectral feature,
only a small redshift domain is accessible : dz~0.05(1+z)
Ex. In the local universe, for the first UV band, we can reach
~2d(Coma) for a given spectral feature (e.g. Ly a).
The spatial resolution decreases with lambda, i.e. as (1+z) for a
given spectral feature ==> In practise, most studies with strong
requirements in spatial resolution will be limited to the « nearby »
universe (z<1).
The end

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