Advanced Topics in Astrophysics, Lecture 5. Radio Astronomy VLBI Science Phil Diamond, University of Manchester

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1 Advanced Topics in Astrophysics, Lecture 5 Radio Astronomy VLBI Science Phil Diamond, University of Manchester

3 Up to 25 antennas 8000 km baselines Frequency range: 327 MHz 43 GHz Disk-based recording: 1 Gbps; e-vlbi routine

NRAO:VLBA 10 25m antennas 8000 km baselines Frequency range: 1.

4 NRAO:VLBA 10 25m antennas 8000 km baselines Frequency range: GHz Digital backends and disk-based recording: 4 Gbps in 2011

5 Long Baseline Array 3000 km baselines; 5000 km with NZ 9000 km with S.Africa Connect to East Asia Frequency range: GHz Disk-based recording: 1 Gbps, moving towards e-vlbi

6 Key aspects of VLBI Long baselines high resolution Sensitive to compact structure high T b In general, variety of antenna sizes and types Bandwidth limited c.f. connected-element arrays because of disk-based recording or fibre transmission capabilities In general, observing done in sessions, e.g. EVN 3 * 3 week sessions per year. VLBA & VERA operate year round.

7 VLBI Science Radio jet & Black hole physics Radio source evolution Astrometry Maria in next lecture Galactic and extra-galactic Masers Gravitational Lenses Supernovae and Gamma-Ray-Burst studies Nearby and distant starburst galaxies Nature of faint radio source population HI absorption studies in AGN

8 Radio Jet and Black Hole Physics Active Galactic Nucleus: Super-massive black-hole at centre of galaxy most powerful objects in the Universe. Visible across the electromagnetic spectrum.

9 Radio Jet and Black Hole Physics M87 = Virgo A Giant elliptical, 17Mpc BH ~ 3x10 9 M sun

10 Radio Jet and Black Hole Physics

11 Radio Jet and Black Hole Physics 3C120: Seyfert galaxy, D=125 Mpc Superluminal jet, appears to move faster than c optical illusion

12 Radio Jet and Black Hole Physics VLBA: 5 GHz 3C120: Seyfert galaxy, D=125 Mpc Superluminal jet, appears to move faster than c optical illusion

13 Radio Jet and Black Hole Physics VLBA movie of 3C120 at 22 GHz: Gomez et al, 2006

25c, lobes are separated by ~90pc => age of radio structure is ~1100 yrs As CSOs grow

14 Radio source evolution VLBI discovered Compact Symmetric Objects (CSOs) Owsianik & Conway (1998, A&A, 337, 69) studied , showed outer lobes moving apart at 0.25c, lobes are separated by ~90pc => age of radio structure is ~1100 yrs As CSOs grow it is presumed they evolve into classical double radio sources. Statistical studies under way

15 Spectra of H 2 O masers NGC Taxonomy Velocity-symmetry, Narrow-lines dominate NGC Circinus 8 Single emission feature Broad-hump dominates NGC Flux Density (Jy) IRAS Heliocentric Velocity (km s -1 )

NGC4258: The archetypal accretion disk maser Kagoya/Inoue Review Accretion Disk: Miyoshi et al. 95 Jet @ 4000R s : Herrnstein et al.

16 NGC4258: The archetypal accretion disk maser Kagoya/Inoue Review Accretion Disk: Miyoshi et al R s : Herrnstein et al. 97 Accelerations: Nakai et al. 95 Greenhill et al. 95 Bragg et al. 00 Distance 7%: Herrnstein et al. 99 BH Mass = 3.9 x 10 6 M sun

17 Other examples: see

18 Jet-driven H 2 O Masers: NGC 1052 Central Engine ++ ~100 km/s Jet Featureless broad lines constitute blends of narrow lines from entrained or shocked ambient material? O.33 pc (Claussen, Diamond & Braatz. 1998, ApJ)

19 Extragalactic H 2 O Megamasers Galaxy Distance (Mpc) Flux (Jy) Galaxy Distance (Mpc) NGC IC Circinus 4 4 NGC NGC NGC M ESO 103-G NGC Mrk NGC ESO 103-G Flux (Jy) NGC Mrk NGC Mrk NGC IC NGC NGC NGC IRAS F

20 25 years of Extragalactic H 2 O masers A rare but astrophysicallyimportant phenomenon. Extragalactic H 2 O masers tag star-formation in nearby galaxies. Proper motion measurements make possible unique measurements (e.g., galaxy motions). But starburst systems need study. H 2 O masers mark 21+ AGN central engines Thin accretion disks, AGN dynamics on < 1 pc scales Entrained or shocked ambient material for jets Jets and NLR-type outflows Other?

21 OH Megamasers (OHM) Discovered by Baan et al (1982) with Arecibo while searching for OH absorption. Until 1998 ~ 30 OHM known. Arecibo upgrade has resulted in a host of new detections. ALL OHM are associated with ULIRGs, ALL ULIRGs appear to be the result of galaxy mergers. Darling & Giovanelli (2001)

The archetypyal OHM: Arp220 Arp220, d~76 Mpc Ultraluminous IR galaxy, L fir > 10 12 L OH megamaser Double

22 The archetypyal OHM: Arp220 Arp220, d~76 Mpc Ultraluminous IR galaxy, L fir > L OH megamaser Double nucleus, tidal tails merger Extreme dust obscuration (A v ~1000) MERLIN: 18cm continuum Arp220: R-band, R Hawaii

23 Arp220 MERLIN continuum image OH megamasers associated with both nuclei Global VLBI observations (17 telescopes in Europe and US, resolution ~3 milliarcsec) showed four compact emission regions (Londale et al, 1998)

BUT VLBI continuum, phase-referenced to the OH megamaser showed ~12 sub-mjy

24 Megamaser + radio supernovae 150pc Continuum point sources Masers Lonsdale et al, 1998 Smith et al, 1998 Diamond et al, 2002 VLBI resolves ~97% of continuum BUT VLBI continuum, phase-referenced to the OH megamaser showed ~12 sub-mjy point sources. We interpret them as: LUMINOUS RADIO SUPERNOVAE: rate of RSN/year

25 Arp220: 49 supernovae Lonsdale et al 2006

expanding circumstellar envelope VLBA: 200 arcsec resolution

26 Stellar masers: SiO TX Cam: 88 weeks Diamond & Kemball, 2002, 2007, 2009 TX Cam is a Mira Variable 377 pc distant AGB star, with thick, expanding circumstellar envelope VLBA: 200 arcsec resolution Predominant motion is outflow, strong evidence for shocks dominating the kinematics

27 Stellar masers: SiO TX Cam Tangential polarisation vectors confined to narrow inner edge of ring. Strong evidence of effects of shocks. Magnetic field ~ 5G

28 Stellar masers: H 2 O Proper motions of masers around stars relatively undeveloped subject until the advent of the VLBA Marvel & Diamond (2010, in prep) B field measurements now possible. Values for several stars indicate B ~ few hundred mg B~280mG (Vlemmings, Diamond & van Langevelde, 2001)

29 Stellar masers: OH Polarization VX Sgr: 1612 MHz MERLIN: Szymczak et al Polzn vectors tangential to circumstellar envelope. Linear polzn ~ 10-20% Structure favours a radial field maybe we are viewing a dipole field end-on. Circular polarization => B ~ 1.1 mg

100s 1000s stellar sources) Greenhill et al, 1999 Doeleman et al, 1999, 2001 Orion KL: X marks

30 Interstellar masers: SiO Not very common, few sources (c.f. 100s 1000s stellar sources) Greenhill et al, 1999 Doeleman et al, 1999, 2001 Orion KL: X marks the spot indicates biconical outflow v=1, v=2, J=1-0 (43 GHz) appear as expected with v=2 lying closer to the exciting source v=1, J=2-1 (86 GHz) lies outside the 43 GHz masers, not known why Major VLBA proper motion programme underway

31 Interstellar masers: SiO

32 Interstellar masers : CH 3 OH: EVN (Minier et al, 2001)

33 Methanol maser: G Bartkiewicz et al, 2008

34 Supernovae M82 V exp ~ 9500 km/s

35 Supernovae M82 Global VLBI at 18cm M82 Supernovae V exp ~ 9500 km/s

36 Supernovae

37 Nature of faint radio source population Faintest radio sources ever detected using VLBI (Garrett et al, 2001) EVN images of sources detected in HDF superimposed on deep optical image. 3 detections are AGN Further observations underway

38 HI Absorption studies EVN+VLBA observations of HI towards CSO (Peck & Taylor, 2001) Indicate circumnuclear torus of neutral gas

39 Evolution in capabilities Observations of line and continuum emission from starburst galaxy Arp220 EVN 1989

40 Evolution in capabilities Observations of line and continuum emission from starburst galaxy Arp220 EVN 1989 Global VLBI 2004 : OH

41 Evolution in capabilities Observations of line and continuum emission from starburst galaxy Arp220 EVN 1989 Global VLBI Global VLBI 2004: continuum 2004

VLBI observations of OH megamaser galaxies (A research plan introduction)

VLBI observations of OH megamaser galaxies (A research plan introduction) Zhongzu Wu(GZU) & Yongjun Chen (SHAO) Collaborated with xingwu zheng(nju), Zhiqiang Shen(SHAO), Dongrong Jiang(SHAO), Zhang Bo,