1 TAUVEX and AGNs T TAUVEX=Tel A Aviv University UV Ex UV Explorer

2 Outline Background Technical description Projected performance Scientific projects (AGNs) Conclusions

3 IUE: all targets Why UV? Earth atmosphere opaque to UV Low sky background! UV range Background

4 Short history of UV astronomy UV range definition: 10 nm to 380 nm First observation: Sun, from V2 (US-NRL) First satellite: TD-1. Sky survey to ~9 mag First spectroscopy: Copernicus Longest duration: IUE Most expensive: HST (only part is UV) TD-1 starlight at nm in 3° bins (Sujatha et al. 2004)

5 Generic UV Targets Comets Hot stars (high-mass, evolved [WD]) Galaxies: evolution Interstellar & Inter- Galactic matter AGNs SMC Hyakutake Hale-Bopp 40 deg

6 TAUVEX history 1989: chosen as 1 st priority by ISA 1991: agreement to launch with SRG 1994: planned launch date 2000: delays with SRG; start search for alternate launch 2003: ISA-ISRO agreement 2007: planned launch on GSAT-4 SRG=Spectrum Roentgen-Gamma (incarnation I) Prime contractor: El-Op, Electro-optical Industries

7 GSAT-4 to geo-synchronous orbit. Platform=technological demonstrator for new generation of Indian communication satellites. TAUVEX has a dedicated communication channel of 1 Mbps, continuously. Satellite has fixed orientation w.r.t. the Earth! To allow unrestricted access to the sky, TAUVEX is mounted on orientable platform (MDP). The Indian connection

8 Toward Earth MDP in launch orientation. MDP motion is up to 180º from the launch position, to -90≤δ≤+90 δ=0º δ=+90º

9 3x20cm RC telescopes ~One-degree images Angular resolution ~7” UV “solar blind” sensitivity Unblocked area ~266 cm²(3x) On GSAT-4, sky scans TAUVEX basics Technical description

10 TAUVEX: filter setup Each telescope with 4- position wheel One position blocked (shutter=CLS) Three positions with filters Filter arrangement SF1 T1: SF1, SF2, BBF, CLS SF3 T2: SF2, SF3, BBF, CLS SF1SF3 T3: SF1, NBF3, SF3, CLS Includes geometric shadowing, 2 mirrors, lenses+windows, filter trasmission & detector QE CaF_2 cutoff

11 Simulated image Drift rate: “Pixel”=3 arcsec Max. “no-smear” time=1/8 sec Basic timescale for data frame Object in FOV: 224 sec along detector diameter at δ=0 (basic exposure time) High declination advantage! (above 81º, more than 1500 sec per pass) TAUVEX performance (and constrains) Projected performance

12 Confusing magnitudes…

13 TAUVEX vs. HST 144x more collecting area than TAUVEX x better resolution 400x smaller FOV (STIS) x higher cost Only operating UV instruments at present are ACS & WFPC-2! HST has:

14 GALEX GALEX launched April 2003 for all-sky UV survey GALEX (1x) and TAUVEX (3x) have similar collecting areas and angular resolution GALEX has one 50-cm telescope and only two spectral bands: FUV & NUV GALEX operates only 1/3 of the orbit AIS like TAUVEX single pass (AB mag limit=18 mono) GALEX NUV= TAUVEX BBF

15 TAUVEX - performance Exposure depth depends on: –Dwell time of object in FOV (“exposure”) –Level of background (Max count rate~100K/sec) Background is stray light: light scattered into the detectors from sources external to the FOV SunStrongest source=Sun Operational solutions: –Filter choice (solar spectrum) –Sky strip selection –Baffle extension Scattered into baffle Reflected by solar panels & thrusters

16 Sensitivity (best case) SF-1 SF-2 SF-3 BBF-worst case BBF-best case To Sun Equal-area projection of celestial hemisphere

17 GALEX vs. TAUVEX GALEX: DIS=80 sq. degrees (~70 fields). Limiting AB=25 (1σ); only small part done yet TAUVEX: DEC=+90 to +85 is equivalent area to DIS Limiting mag’s (5σ) for single scan are: – SF1-3: monochromatic (AB=21-23) –BBF: gain one mag To surpass GALEX DIS, TAUVEX requires 10 scans of the Polar Cap area! This is 1-2 months of observations. GALEX DIS field: Groth region, 14ksec exposure

18 TAUVEX science: AGNs Detection (star-AGN photometric separation) Rough redshift determination (UV dropouts) Variability studies Composite AGN spectrum (Telfer et al. 2002, ApJ 565, 773) Projected results

19 How many low-z AGNs? AGNs per square degree, with z<1, to different limiting magnitudes. Conclusion: TAUVEX will find significant numbers of low-z AGNs N

20 Red≡stars, green ≡ galaxies, light blue ≡ AGNs.+reddening GALEX+SDSS (Bianchi et al 2004) GALEX AGNs: UV vs. optical colors

21 TAUVEX: UV+optical colors z Nearby AGNs (z<1) UV-UV

22 z z TAUVEX: UV+optical colors

23 z including Ly limit and Ly forest Importance of simultaneous UV & optical measurements! UV-UV

24 Conclusions TAUVEX offers similar performance to GALEX, with important enhancements: –Three simultaneous bands –Five different filters (flexibility) –Time-resolved photometry over a number of time scales: 1/8 sec to 100s of sec for single pass; revisits Launch 20 February 2007

25

26 TAUVEX on GSAT4: GENERAL VIEW New features: Rotating plate Front radiator Extra baffle Extra shielding Thermal couplings MDP

27 Performance: SF-1 Equal-area plot, hemisphere

28 Performance: SF-2

29 Performance: SF-3

30 Performance: BBF

31 TAUVEX: detection system Wedge (A) Strip (B) Zig-zag (C) Detection=(x, y, t) (Approx. 700 “pixels” across FOV)

32 TD-1A & IUE All-sky photometric survey to 9 mag Targeted mission: spectroscopy

33 TAUVEX science: stars & ISM B star UV spectrum Use SF2 and NBF3 to measure the EW of the ISM band TD-1 PAHs distribution?

34 TAUVEX science: galaxies UV light understand physics of star-forming processes, extinction Late-type galaxies=good targets GALEX 1300 sec image

35 Antennae galaxies (NGC4039/4039): importance of the UV sensitivity to establish the nature of stellar populations and determine the full IMF TAUVEX science: galaxies II Lyman cont`.HαHα Hot stars (O,B,A)FUV, NUV Stars (F,G,K,M)Optical (UBVRI) Stars (K, M)Near-IR Almoznino & Brosch 1998

36 TAUVEX science: galaxies III UV observations track the history of star formation in the last billion years

37 TAUVEX science: UV-dropouts (cosmology) Select z=1-2 galaxies from UV dropouts

38 Real image: distortion pattern “Flat-field” (collimator) TAUVEX: lab performance Next More? Edge discharge

39 Comments Volume log #Gals m lim Expos [ksec] Length [Month] Area [deg] SURVEY Galactic caps first ,000All-sky (AIS) SDSS, 2dF overlap0.6~ Medium Imaging (MIS) Fields Deep Imaging (DIS) Fields Ultra-Deep Image (UDIS) Galaxy List m per sq. deg Nearby Galaxy (NGS) Same fields as DIS Wide Spectroscopic (WSS) Centers of WSS Medium Spectroscopic (MSS) Fields Deep Spectroscopic (DSS) Guest Investigator Cycle 1 GALEX surveys (AB)

40 GALEX-technical Uses dichroic beamsplitter Two crossed-delay line MCP detectors (2kx2k) Insertable grism for low-resolution spectra Pegasus launch to LEO Pegasus launch

41 Assume best case=no stray light Performance (S/N=5) with SF-2 for stars of different spectral types Lines for monochromatic mag. 17, 18, 19, 20, 21 star O BA G (better than GALEX!) TAUVEX: performance (GSAT-4)