Observations of AGN with MIDI or „How to cope with faint targets with MIDI“ EuroSummer School Observation and data reduction with the VLTI Konrad R. W. Tristram MPIA Heidelberg

Konrad R. TristramPage 2 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 3 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 4 Introduction: What are AGN? AGN (Active Galactic Nucleus): supermassive black hole (M > 10 6 M  ) at the centre of a galaxy actively accreting Large range of energetic phenomena: –X-ray emission –Ionisation cones –broad and narrow line regions –jets –…. Urry and Padovani, 1995

Konrad R. TristramPage 5 Introduction: The Unified scheme Unified AGN model: Geometrical effects lead to different manifestations (e.g. Seyfert 1 & 2) Broad Line Region Accretion Disk Obscuring Torus Ionisation Cone Black Hole

Konrad R. TristramPage 6 Introduction: The SED of AGN log(ν) in Hz log(νL ν ) in erg/s 1.2 keV 120 eV 10 nm 100 nm 1 µm 10 µm 100 µm 1 mm 1 cm 1 dm blue bump IR bump Ly α line soft excess Elvis et al., 1994

Konrad R. TristramPage 7 Introduction: Key questions Key questions: –What is history and evolution of AGN? –How is the accretion energy released? –What is the interplay between black hole and its host? –Is the picture of the unified scheme true? Search for direct evidence for dust torus –Observations in the MIR –Sufficient spatial resolution

Konrad R. TristramPage 8 Introduction: Nearby AGN NameTypeDistance [Mpc] 1 pc [mas] Flux [Jy] NGC 1068Sy CircinusSy NGC 4151Sy NGC 5128Sy NGC 5506Sy NGC 1365Sy MCG Sy Mrk 1239Sy NGC 3783Sy NGC 3281Sy IRS Sy

Konrad R. TristramPage 9 Introduction: Why MIDI? Need MIR instruments with highest resolution!  Find this only at the VLTI: MIDI Goal for MIDI: –Resolve the putative dust torus directly for nearby active galaxies! VLT with the Residencia February 2005

Konrad R. TristramPage 10 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 11 Observations: Target list List of all AGN observed to date: NameFlux (10µm)TimeIn charge NGC 1068 (M77)13 JySDT / OTRaban Circinus5 JyGTOTristram NGC 5128 (Centaurus A)0.6 JyGTOMeisenheimer NGC JyOTBeckert Mrk JyGTOCotton MCG JyGTOCotton

Konrad R. TristramPage 12 Observations: Acquisition Example for a bright calibrator: HD First iteration Flux: 10 Jy Filter: N8.7 DIT = NDIT = 1000 Beam ABeam B

Konrad R. TristramPage 13 Observations: Acquisition Example for a bright calibrator: HD Second iteration Flux: ~10 Jy Filter: N8.7 DIT = NDIT = 1000 Beam ABeam B

Konrad R. TristramPage 14 Observations: Acquisition Example for a bright calibrator: HD Third iteration Flux: ~10 Jy Filter: N8.7 DIT = NDIT = 1000 Beam ABeam B

Konrad R. TristramPage 15 Observations: Acquisition Example for a ‘bright’ AGN: Circinus galaxy First iteration Flux: 5 Jy Filter: SiC DIT = NDIT = 1000 Beam ABeam B

Konrad R. TristramPage 16 Observations: Acquisition Example for a ‘bright’ AGN: Circinus galaxy Second iteration Flux: 5 Jy Filter: SiC DIT = NDIT = 2000 Beam ABeam B

Konrad R. TristramPage 17 Observations: Acquisition Example for a ‘bright’ AGN: Circinus galaxy Third iteration Flux: 5 Jy Filter: SiC DIT = NDIT = 2000 Beam ABeam B

Konrad R. TristramPage 18 Observations: Acquisition Example for a faint AGN: Mrk1239 First iteration Flux: 0.6 Jy Filter: SiC DIT = NDIT = 8000 Beam ABeam B

Konrad R. TristramPage 19 Observations: Acquisition Example for a faint AGN: Mrk1239 Second iteration Flux: 0.6 Jy Filter: SiC DIT = NDIT = 8000 Beam ABeam B

Konrad R. TristramPage 20 Observations: Acquisition Example for a faint AGN: Mrk1239 Third iteration Flux: 0.6 Jy Filter: SiC DIT = NDIT = Beam ABeam B

Konrad R. TristramPage 21 Observations: Fringe search Fringe-Search on Mrk 1239 Fringe search and tracking then seems easy!

Konrad R. TristramPage 22 Observations: Fringe tracking Circinus

Konrad R. TristramPage 23 Observations: Fringe tracking MCG

Konrad R. TristramPage 24 Observations: Photometry HD Beam A without additional sky subtraction prism DIT = NDIT = 1500

Konrad R. TristramPage 25 Observations: Photometry HD Beam A with additional sky subtraction prism DIT = NDIT = 1500

Konrad R. TristramPage 26 Observations: Photometry Centaurus A Beam A without additional sky subtraction prism DIT = NDIT = 10000

Konrad R. TristramPage 27 Observations: Photometry Centaurus A Beam A with additional sky subtraction prism DIT = NDIT = 10000

Konrad R. TristramPage 28 Observations: Photometry Centaurus A Beam B without additional sky subtraction prism DIT = NDIT = 10000

Konrad R. TristramPage 29 Observations: Photometry Centaurus A Beam B with special sky subtraction prism DIT = NDIT = 10000

Konrad R. TristramPage 30 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 31 Data reduction What does EWS do? 1. data compression 2. background removal 3. instrumental OPD demodulation 4. atmospheric delay removal 5. determination of the differential phase 6. coherent integration  visibility and differential phase How to run EWS? IDL> midipipe, tag, files IDL> midicalibrate, scitag, caltag

Konrad R. TristramPage 32 Data reduction Almost exclusively with EWS Usage of optional settings (smooth, gsmooth, /dave) Calibrations problems: –usage of geometric or arithmetic photometry –Non detections  midisearch

Konrad R. TristramPage 33 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 34 NGC 1068: first results Jaffe et al Two baseline orientations Modelled by two elliptical Gaussians: –Hot and cold component –Different silicate absorption

Konrad R. TristramPage 35 NGC 1068: first results Jaffe et al Confirmation of the unified scheme!

Konrad R. TristramPage 36 NGC 1068: new observations Grism observations Open time independent visibility points Period 76, 2005 u in m v in m

Konrad R. TristramPage 37 Circinus: properties Spiral galaxy SA(s)b, i = 65° Seyfert type 2 4 × 10 6 M  nucleus Distance ~4 Mpc → 50 mas ~ 1 pc 2MASS J, H, K s colour mosaic

Konrad R. TristramPage 38 Circinus: UV plane u in m v in m Period 72, (U3-U2) Period 73, (U3-U2) Period 74, (U3-U4) Period 75, (U2-U3) Period 77, (U2-U3) U2-U4 GTO observations from P72 to P77 15 independent visibility points (several ‘double’) some of these rather “dodgy”

Konrad R. TristramPage 39 Circinus: Correlated flux Wavelength λ in µm Flux in Jy Calibrated Correlated Flux ozone Circinus, observed: PA= 44°, BL=49.4m PA= 54°, BL=51.1m PA= 57°, BL=51.7m PA= 88°, BL=58.2m PA=120°, BL=62.0m PA=131°, BL=62.4m N

Konrad R. TristramPage 40 Circinus: Results Known geometry 1’’~ 20 pc O[III] Tristram et al Expected torus configuration

Konrad R. TristramPage 41 Circinus: Results Measured geometry at 8.5 µm Tristram et al RA in mas DEC in mas 0.46 pc 0.70 pc

Konrad R. TristramPage 42 Circinus: Results Measured geometry at 13 µm Tristram et al RA in mas DEC in mas 0.70 pc 1.1 pc Confirmation of the unified scheme!

Konrad R. TristramPage 43 Centaurus A: properties Elliptical galaxy dust lane edge-on Seyfert type 2 FR 1 radio galaxy 6 × 10 7 M  nucl. Distance ~4 Mpc → 50 mas ~ 1 pc

Konrad R. TristramPage 44 Centaurus A: UV plane Period 74, (U3-U4) Period 75, (U2-U3) u in m v in m GTO observations in P74 and P75 4 independent visibility points problems with photometry

Konrad R. TristramPage 45 Centaurus A: visibilities Wavelength in µm Visibility PA= 96°, BL=58.0m PA=119°, BL=62.0m Calibrated Visibility Centaurus A, observed: ozone No dust torus? Synchrotron emission?

Konrad R. TristramPage 46 Faint AGN

Konrad R. TristramPage 47 Faint AGN

Konrad R. TristramPage 48 Faint AGN

Konrad R. TristramPage 49 Faint AGN Observation time for faint targets: MCG ―57 min Mrk 1239―53 min Mrk 1239―50 min  1 hour for faint target + ½ for calibrator. No problem tracking 200 mJy correlated flux. High visibility on sources

Konrad R. TristramPage 50 Contents Introduction: AGN, unified scheme, SED, key questions, why MIDI? Observations: acquisition, tracking and photometry for weak targets Data reduction: EWS Results for observed sources: NGC1068, Circinus, Centaurus A, weaker sources Prospects and advice

Konrad R. TristramPage 51 Prospects Long baselines for unresolved targets Shorter baselines for highly resolved targets  try ATs (?) Extension of sample (need FINITO)

Konrad R. TristramPage 52 Conclusions Only limited sample of observable AGN “Inconclusive” results To study more objects an increase of sensitivity needed