Introduction to and methods of SPACE-based observational astronomy

Introduction to and Introduction to and methods of SPACE-based methods of SPACE-based observational astronomyobservational astronomy

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MAGPOP School (Budapest, Aug 23-25 2006)

Armando Gil de Paz (Universidad Complutense de Madrid)

3rd lecture

SchemeScheme 1 st


• James Webb Space Telescope (JWST)

• IUE, IRAS, ISO dataPast Missions:

Future:

Space-based Astronomy Tools and Science:

• Use of Space-based data

• Synergy with ground-based data (e.g. HST-Keck/VLT, JWST-ALMA)

Today’s lecture

Past missions: IUEPast missions: IUE 1 st

MAGPOP School (Budapest, Aug 23-25 2006) • Partners: Joint NASA, ESA, PPARC mission. 19

years operational (from its launch in 1978 to 1996).

• Orbit: Geosynchronous over Atlantic.

• Telescope: 45-cm f/15 Ritchey-Chretien Cassegrain.

• Instrument:

• Echelle spectrograph (1150-1980 ÅÅ, 1800-3350 ÅÅ) with 3” and 10”x20” apertures and high (0.1 Å) and low-resolution (6 Å) modes. Image quality: 2”

• Cameras: SWP, LWP (short and long-wavelength prime), & SWR, LWR (redundant cameras).

• Archive: 110000 spectra extracted from 104000 IUE images. Maintained at Villafranca tracking station (spectra processed using ESA’s INES software) at http://ines.laeff.esa.es/. A copy is also available through MAST although using an older pipeline version.

IUE summary:

IUE: IUE: Archival Archival

DataData

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Past missions: IRASPast missions: IRAS 1 st

MAGPOP School (Budapest, Aug 23-25 2006) • Partners: Joint project of the US, UK, and

the Netherlands. Launched in January 1983.

• Orbit: Sun-synchronous near-polar (99o).

• Telescope: 57-cm f/9.6 Ritchey-Chretien.

• Instruments: Survey Array, CPC, LRS.

IRAS summary:

IRAS focal plane

IRAS: Archival DataIRAS: Archival Data 1 st


Past missions: ISOPast missions: ISO 1 st

MAGPOP School (Budapest, Aug 23-25 2006) • Partners: ESA with the participation of ISAS & NASA. Built by

Aerospatiale (now Alcatel). Launched by an Ariane IV in November 1995. Scientific observations were carried out between Feb’96-Apr’98. • Orbit: 24h-period high orbit inside and outside the Van Allen belts. Detectors unusable inside the belts.

ISO: InstrumentsISO: Instruments 1 st

MAGPOP School (Budapest, Aug 23-25 2006) • ISOCAM: Two imaging channels with

32×32 arrays operating between 2.5-5.5 um & 4-17 um and 21 filters (11 SW+10 LW).

• LWS: It covered the range 43-200 um with R∼200 (R~10000 using Fabry-Pérot etalons).

• ISOPHOT: Consists of three subsystems:

• ISOPHOT-C, with two photometric cameras covering the range 50-240 um.

• ISOPHOT-P, a multi-band, multi-aperture photo-polarimeter @ 3-110 um.

• ISOPHOT-S, a dual grating spectro-photometer with R~90 in two simultaneous bands (2.5-5um & 6-12um).

• SWS: It covered the range 2.4-45 um with R= 1000-2500 (25000 with FP etalons).

M51 (ISOCAM LW3 - 14.5 um)

PHT-S SWS LWS

Points: PHT-C/P

ISO: Archival DataISO: Archival Data 1 st


Future missions: JWSTFuture missions: JWST 1 st

MAGPOP School (Budapest, Aug 23-25 2006) James Webb Space Telescope: Summary

• Developed by an industrial consortium under NASA’s supervision in collaboration with ESA (mostly for instrument development).

• High orbit around the L2 Sun-Earth Lagrange point. Launch ~2013 by an Ariane V rocket.

JWST: InstrumentsJWST: Instruments 1 st


SPACE-based Astronomy SPACE-based Astronomy Tools & ScienceTools & Science

(just a few examples)(just a few examples)

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Space-based Astronomy T&SSpace-based Astronomy T&S 1 st

MAGPOP School (Budapest, Aug 23-25 2006) PSF photometry:PSF photometry:

• Critical for crowded fields, Supernova photometry, diffraction-limited images.

• Not for use with -even marginally- resolved sources.

Procedure:Procedure:• Determine PSF empirically from field stars, analytically (2D Gaussian, Lorenzt, Moffat) , or Hybrid.

• Minimize:

ACS PSFNICMOS PSF

MIPS PSF

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• PSF-photometry software: ROMAFOT, STARMAN, DAOPHOT (Stetson 1987), DoPHOT, HSTPHOT

• Alternatives: Aperture photometry, Sextractor, TFIT

PSF-photometry science (HST CMD of nearby galaxies):PSF-photometry science (HST CMD of nearby galaxies):

Gallart et al. (1999)

daophot + addstar + daophot

Space-based Astronomy T&SSpace-based Astronomy T&S

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MAGPOP School (Budapest, Aug 23-25 2006) Low background (Poisson statistics):Low background (Poisson statistics):

• mean ≠ median ≠ mode

• In extreme cases (FUV) most background pixels are zero.

GALEX FUV flux vs. HI (texp=100s)

GALEX FUV flux vs. HI (texp=1500s)GALEX FUV flux vs. HI (texp=30000s)


Braine et al. (2006, in prep.)

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MAGPOP School (Budapest, Aug 23-25 2006) New windows: UVNew windows: UV

• IRX- law: Since the intrinsic UV slope is approx. constant for continuous SF or smoothly-evolving SF histories, the measured UV slope provides a good estimate of the UV extinction. Good for not heavily extincted objects.

• In highly attenuated objects the UV-to-TIR flux ratio can be used.


• SFR: The UV luminosity (once corrected for extinction) is a good Star Formation Rate tracer (via IMF). Sensitive to very low-levels of SF at low metal abundances (e.g. extended UV).

• UV upturn: Unexpected FUV rising flux in evolved stellar populations. First discovered in the nucleus of M31 by the OAO. Emission from BHB stars is suspected. The slope of the integrated CMD is opposite to that seen in the optical.

M83

NGC1512

GALEX Optical HI 21cm

GALEX Optical HI 21cmGil de Paz et al. (2006); IRX-beta (Meurer et al. 1995, 1999) Favored extinction law

Gil de Paz et al. (2006)

E/S0

Boselli et al. (2005)

Z

Roussel et al. (2005)

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MAGPOP School (Budapest, Aug 23-25 2006) New windows: IRNew windows: IR

• UV-to-TIR ratio: The best estimate of the UV extinction. It is almost independent of dust properties, geometry, and SFH (Buat et al. 2005).


• SFR: FIR emission due to dust heated by young hot stars: Good measure of the SFR. Advantage: It is extinction free. Disadvantage: Dust also heated by optical photons, especially a longer wavelengths (cooler dust). Thus, the 24 um luminosity provides the best correlation with extinction-corrected H-based SFRs (Calzetti et al. 2006: Pérez-Gonzalez et al. 2006).

• MIR diagnostics: The study of the MIR provides important clues on: (1) Formation and excitation conditions of PAHs

(2) The relevance of stochastically-heated VSGs (3) The chemical composition of evolved stellar populations (e.g. Silicates feature).

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Synergy with ground-based astronomySynergy with ground-based astronomy

Nearby Galaxies: Spitzer + GALEX imaging combined with ground-based corollary data. Some examples:• Roussel et al. (2005) on NGC300

• Dale et al. (2006) on 75 SINGS objects.

• Perez-Gonzalez et al. (2006) on M81

• Thilker et al. (2006) on NGC7331.

Radial and small-scale properties of extinction, dust temperature, SFR; multi-wavelength SEDs for local templates. Dependence of dust attenuation properties with the clusters’ evolutionary stage.

NGC300

Roussel et al. (2005)

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Cosmological redshift surveys (HST-Keck/VLT): • HST is not optimized for measuring redshifts of faint distant galaxies (just a 2.5m!)

• Redshifts have traditionally come from 8-10m telescopes such as Keck, VLT, Gemini…

• Unfortunately, most sources in deep imaging surveys with HST (HDF, UDF) are well beyond the spectroscopic limit (IAB~25-26).

Objective of new 30-m class telescopes (TMT,GMT,OWL).

photo-z

6m

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Future surveys (JWST-ALMA-30m synergy):

• ALMA will provide an unprecedented sample of very distant galaxies thanks to the negative K-correction.

• Targeted JWST programs will allow deriving rest-frame optical properties with superb resolution.

• 30m-class telescopes should provide redshifts for ALMA sources with faint molecular-line emission.

… and (in some cases) in 3D using IFUs!

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The EndThe End

Some notes on the Some notes on the CD-ROM contentCD-ROM content & & Proposal-making practical sessionProposal-making practical session

Documents

Introduction to and methods of SPACE-based observational astronomy