Sándor Frey FÖMI Satellite Geodetic Observatory P.O. Box 546, H-1373 Budapest, Hungary Space VLBI

Very Long Baseline Interfero- metry Space

SVLBI in principle: ground-space baseline

8-m parabolic antenna on board HALCA observing frequencies: 1.6 and 5 GHz recording data rate: 128 Mbps bandwidth: 32 MHz orbital period: 6.3 h km (apogee) 560 km (perigee) baselines: up to ~ km VSOP (VLBI Space Observatory Programme) ISAS (Japan) HALCA start: February 12, 1997 (new M-V rocket)

Highly Advanced Laboratory for Communications and Astronomy

Usuda 64 m Usuda 10 m a truly global VLBI: >40 ground radio telescopes from all over the world 5 ground tracking stations (USA, Japan, Australia, Spain) 3 correlators (USA, Canada, Japan)

VSOP scientific program General Observing Time (~50% of operational time) open for the scientific community via peer-reviewed proposals (deadlines now coincide with ground VLBI deadlines, 3 times per year) a few declared key science programs: * * blazars * * high brightness temperature / intra-day variability * * jet motions (3C 273, 3C 279 and 3C 345) * * key sources (NGC 4258, Centaurus A and Virgo A) * * nearby AGN * * absorption in AGN * * stars

VSOP scientific program (cont.) VSOP Survey Program (~25%) led by the mission at ISAS coordinated by the international Survey Working Group ~200 brightest, pre-selected AGN to be imaged at 5 GHz limited ground resources (typically 3-5 GRTs) mainly S2 recording + “extractions” from GOT experiments homogeneous information on sub-mas structures, for statistical studies data base will be publicly available

Fomalont et al. (2000), ApJS 131, 95

Selected VSOP scientific results Selection criteria for inclusion in this talk: spectacular certain people in this room are involved... interesting … including myself important

Large collections of various VSOP-related papers: "VSOP Results and the Future of Space VLBI", Proc. COSPAR Symposium, Nagoya, Japan, July 1998, eds. Hirabayashi H., Preston R.A. & Gurvits L.I., Advances in Space Research 26, No. 4 (2000) "Astrophysical Phenomena Revealed by Space VLBI", Proc. VSOP Symposium, Sagamihara, Japan, January 2000, eds. Hirabayashi H., Edwards P.G. & Murphy D.W., ISAS (2000) VSOP Special Issue, Publications of the Astronomical Society of Japan 52, No. 6 (2000)

Orion-KL water maser outburst the only VSOP 22 GHz peak: 1.3  10 5 Jy/beam elongated structure + VLBA monitoring: overlapping maser spots? Kobayashi et al. 2000, VSOP Symp., 109

1519–273 at 1.6 GHz the first-ever SVLBI image, June 1997 VLBA & VLA HALCA added

M87 (Virgo A) VLA VSOP 1.6 GHz Reid 1998, Science 281, 1815 No proper motion is detected in 1.5 years VSOP 5 GHz (in contrast with superluminal motion at VLA & HST scales) Junor et al. 2000, VSOP Symp., 13

Lobanov et al. 2000, AdSpR 26, 669 Lobanov et al. 2000, VSOP Symp., 239 the impact of improved angular resolution: transverse jet structure resolved edge-brightening regular, oscillating patterns: instabilities propagating along the jet

circumpolar superluminal quasar, ideal for VSOP monitoring substantial changes near the core on ~months time scale a variety of different phenomena, inconsistent with a simple straight jet model Murphy et al. 2000, VSOP Symp., (z=0.3) monitoring core 1997 Aug Dec Apr Jul 9

VSOP 5 GHz Chandra X-ray (color) Australia Telescope Compact Array (8.4 GHz, contours) 0637–752 quasar (z=0.65) Lovell et al. 2000, VSOP Symp., 215 first Chandra target, thought to be unresolved  luminous kpc-scale X-ray jet 1999 Aug: coordinated VSOP and Chandra observations radio (ATCA) vs. X-ray jet structure: striking coincidence and radio jet bending polarization E-vectors perpendicular to the jet until X-rays detected to W, then begin to be parallel with the jet simple synchrotron model is not sufficient to explain all data (incl. HST optical) VSOP/VLBI: mas-scale jet direction, ~11c superluminal motion

The most distant radio-loud quasars (z>3) (z=3.57) VLBA+EVN 1.6 GHz + baselines to HALCA included resolved jet cross-section  ~4·10 9 M o estimated cental black hole mass J4 Lobanov et al. 2001, ApJ 547, 714

(z=3.71) earlier 5 GHz Frey et al. 1997, A&A 325, GHz: dramatic change in jet direction between sub-mas and ~10 mas scale

… but: / quasar pair (14.3 arcmin separation) HALCA primary beam: 26 5 GHz VLBA + Effelsberg switched between the sources phase reference mapping, relative astrometry with VSOP / quasar pair (4.8 arcsec separation) sources lie within the primary beam of HALCA & VLBA antennas it works! satellite orbit reconstruction error ~3 m VSOP phase-referencing HALCA cannot switch rapidly between sources... Guirado et al. 2001, A&A 371, 766 Porcas et al. 2000, VSOP Symp., 245

VSOP polarization HALCA receives only left-circularly polarized radiation... … but: despite the other complications (lower sensitivity, difficult polarization calibration), it is technically feasible to obtain high- resolution polarization images test observations with the VLBA and 1.6 and 5 GHz of sources with sufficiently high correlated polarized flux density good perspectives for next-generation SVLBI Kemball et al. 2000, PASJ 52, 1055

a highly variable BL Lac 5 GHz: the highest brightness temperature measured with VSOP T B > 5.8  K Frey et al. 2000, PASJ 52, 975

The Pearson-Readhead Survey from Space Lister et al. 2001, ApJ 554, 948 HALCA + VLBA + EVN imaging of 27 sources from the P-R survey (Pearson & Readhead 1988, ApJ 328, 114) original sample: 65 sources (  >35 , S 5 >1.3 Jy,  b  >10  ) sub-sample for SVLBI: S corr >0.4 Jy on ground baseliness (BL 5 GHz ground-only SVLBI

imaging: true dynamic range typically 30:1 … 100:1 Tingay et al. 2001, ApJ 549, L55 The Pearson-Readhead Survey from Space: results brightness temperature distribution: a significant proportion has T B >10 12 K relation between high T B and IDV activity source properties: correlation analysis (morphology, IDV, core dominance, optical polarization, emission line equivalent width, etc.)  support to the beaming model Lister et al. 2001, ApJ 554, 948 Lister et al. 2001, ApJ 554, 964

The VSOP Survey Program: preliminary results Hirabayashi et al. 2000, PASJ 52, 997 sample: among 402 sources (S 5 >0.95 Jy,  >–0.45,  b  >10  ), 289 sources sufficiently compact for 5 GHz ~half of the data sets reduced, even more observed rest-frame brightness temperature (T B ) distribution shows apparent violation of inverse Compton limit (~10 12 K)  relativistic beaming is common

VSOP proposals, observations and data reduction open proposals; deadlines: 1 February, 1 June & 1 October all info at: Proposers’ Guide, cumulative observation list, etc. severe observing constraints (on-board equipment, tracking, ground network availability, etc.) assistance: user software, sample (u,v)-coverages schedule is done by the VSOP mission data reduction: AIPS and Difmap are available calibration information on the VSOP web general info: newsletter (also on the web, with some delay)

SVLBI: technically feasible, scientifically interesting  next generation satellites with improved performance (sensitivity, frequency coverage, etc.) Next generation Space VLBI VSOP-2 is being proposed at ISAS in Japan 10  increase over VSOP sensitivity km apogee 10-m antenna frequencies: (1.6?), 5(8), 22, 43, (86?) GHz data rate: 1 (2?) Gbit/s launch vehicle: modified M-V launch: 2008 ?

ARISE (Advanced Radio Interferometry between Space and Earth) 5  ground-based resolution (max  as) 50  VSOP sensitivity km apogee 25-m inflatable antenna frequencies: 5(8), 22, 43, 86 GHz single-dish: 60 GHz data rate: 8 Gbit/s lifetime  3 years launch: 2008 ?.