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 ... - PowerPoint PPT Presentation
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FRENEL Meeting, Nice, 23-25 September 2009
FRESNEL Imager: FRESNEL Imager: Extragalactic Science in Extragalactic Science in the UV-Optical domainsthe UV-Optical domains
Roser Pelló Roser Pelló Laboratoire d’Astrophysique de Toulouse-TarbesLaboratoire d’Astrophysique de Toulouse-Tarbes
FI and extragalactic studiesFI and extragalactic studies Spatial resolution
Wavelength coverage (100nm to 10 microns)
High dynamic range
FI ...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 utra-deep 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 UVExtragalactic studies in the UV
Galaxy Evolution Explorer (GALEX, 2003-)
GALEX FUV
GALEX NUV
Ex.: composite Ex.: composite spectra of high-z spectra of high-z galaxies observed galaxies observed in the optical in the optical domaindomain(VVDS Survey(VVDS SurveyLe Fevre et al. 06,Le Fevre et al. 06, Paltani et al. 07)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 redshiftLine diagnostics and redshift
near-IR
visible
Ly a
HeII 1640
[OII]3727Hb + [OIII]5007Hb + [OIII]5007Ha + [NII]
Line diagnostics and redshiftLine diagnostics and redshift
Line diagnostics shift towards the near-IR (lambda>1 micron)
Ha/[NII][S II]
AGN
Starbursts
Empirical Empirical discrimination discrimination between between AGN/starburstsAGN/starbursts
From Erb et al. 06
87 combined spectra of galaxies at z~2 (~14-15 specta/ mass bin)
AGNAGNaccretion disk (~0.01 pc)accretion disk (~0.01 pc)
HII regionsHII regions
Conclusions (I)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)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: multiple-imaged 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: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).