Extragalactic science with the Herschel Space

Observatory

Marc SauvageCEA/DSM/DAPNIA

Service d'Astrophysique

UMR AIM

The Herschel Space Observatory

•A European Space Agency (ESA) mission with a NASA participation.

•3.5 m, passively cooled (80 K) telescope in space.

•Located at the L2 Lagrange point of the earth-sun system.

•Operating in the Far-Infrared to Submillimeter range (60-700 µm).

•Cryogenically and actively cooled instruments (detector temperature < 1 K).

•3.5 years nominal lifetime.•OfficialLaunchDate: August 2007.

Herschel’s science objective in a nutshell

Turn a nice and simple grey-body curve into a complicated mess of broad solid-state features underlying a forest of lines…

More seriously

Observe star-forming galaxies in a range where they emit most of their flux, taking advantage of the redshift

Herschel's payloadHerschel will cover the FIR-Submm with three instruments:

HIFIHigh resolution

heterodyne spectrometer

Wavelength coverage: 157-625 µmSingle Beam 12-40”High spectral resolution (up to 107)

Limited capacities for extragalactic science

Herschel's payloadHerschel will cover the FIR-Submm with three instruments:

PACSBolometer camera and low resolution photoconductor

spectrometer60-200 µm

Photometer:3 bands at 75, 110 and 170 µm1.8’x3.5’ fully sample field of viewBeam size 6”, 8” and 12”Spectrometer:Imaging provided through image slicer0.8’x0.8’R=1000-2000

Herschel's payloadHerschel will cover the FIR-Submm with three instruments:

SPIREBolometer camera and fourier transform low

resolution spectrometer200-600 µm

Photometer:3 bands simultaneously at 250, 360 and 520 µm4’x8’ field of view (not fully sampled)Beam size 18”, 25”, 36”Spectrometer:200-670 µm2.6’ circular field of view (not fully sampled)R=20->1000 (FTS)

Extragalactic Science with Herschel

Note: Herschel was built to make surveys but, galaxy deep surveys are not the only kind of surveys…

>1/3 of the time will be dedicated to Galactic star formation.

SPIRE & PACS will be the instruments of choice for distant or faint extragalactic objects

Sensitivities as of almost today:

SPIRE PS imaging 3-10 mJy 5 1hr (obs. mode dependent, but all three bands)

PACS PS imaging 3 mJy 5 1hr (two bands simultaneously)

Confusion will be the main limitation of extragalactic science with Herschel

Observing with Herschel

This will be a déjà-vu situation (Herschel is borrowing a lot from Spitzer)

Four program categories:•Garanteed Time (32%)

• Key programs• Regular projects

•Open Time (68%)• Key programs• Regular projects

• L-21m: Key Programs GT submitted

• L-18: Key Programs GT published• L-15: Key Programs OT submitted• L-12: Key Programs OT published• L-9: cycle 1 GT submitted• L-6: cycle 1 GT published• L: Launch• L+9: cycle 1 OT submitted• L+12: cycle 1 OT published• L+21: cycle 2 GT submitted• L+24: cycle 2 GT published• L+27: cycle 2 OT submitted• L+30: cycle 2 OT published• L+42: nominal end of mission

Science timeline

Current situation

Instrument Consortia have prepared a relatively detailed version of their Key Programs (but these over-use the available time).Still to be done is the negotiation between consortia regarding the program contents (competition on GT is not allowed)

•Spectral survey of starburst and AGNs•Photometric survey of the local volume•Photometric survey of active galaxies•Imaging and spectral study of nearby

galaxies•Imaging and spectral study of dwarf

galaxies•Galaxy deep surveys:

• Cosmic IR background• Evolution of the star formation rate and IR luminosity• Environment effects• AGN contribution• Extreme galaxies at very high redshifts

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Contributing to the Herschel Surveys

For most of the surveys objective, the guaranteed time available is not sufficient.

Open time key programs will be necessary to reach these objectives.

• Build your own consortium (in the spirit of the Spitzer Legacy Programs).

• Join existing initiatives and for this contact Steve Eales (Steve.Eales@astro.cf.ac.uk) or visit http://astronomy.sussex.ac.uk/~sjo/extrahot/