Sándor FreyFÖMI Satellite Geodetic Observatory

P.O. Box 546, H-1373 Budapest, Hungary

frey@sgo.fomi.hu

http://www.sgo.fomi.hu/vlbi/

Space VLBI

VeryLongBaselineInterfero-metry

Space

SVLBI in principle: ground-space baseline

8-m parabolic antenna on board HALCA

observing frequencies:1.6 and 5 GHzrecording data rate: 128 Mbps bandwidth: 32 MHz

orbital period: 6.3 h21 400km (apogee)560 km (perigee)

baselines: up to ~30 000 km

VSOP (VLBI Space Observatory Programme)

http://www.vsop.isas.ac.jp/

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 telescopesfrom 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:

spectacularspectacular

certain people in this room are involved...certain people in this room are involved...

interestinginteresting

… … including myselfincluding myself

importantimportant

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 image @ 22 GHz

peak: 1.3 105 Jy/beam

elongated structure

+ VLBA monitoring:overlapping maser spots?

Kobayashi et al. 2000, VSOP Symp., 109

1519–273 at 1.6 GHzthe 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 monitoring @ 5 GHz(in contrast with superluminal motionat VLA & HST scales)

Junor et al. 2000, VSOP Symp., 13

Lobanov et al. 2000, AdSpR 26, 669Lobanov 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., 47

1928+734 (z=0.3) monitoring

core

1997 Aug 22 1997 Dec 16 1998 Apr 29 1998 Jul 9

VSOP5 GHz

Chandra X-ray(color)

Australia TelescopeCompact 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 coincidenceand 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)

2215+020 (z=3.57)VLBA+EVN ground-only @ 1.6 GHz

+ baselines to HALCA includedresolved jet cross-section

~4·109 Mo estimated cental black hole mass

J4

Lobanov et al. 2001, ApJ 547, 714

1351-018 (z=3.71)earlier VLBA @ 5 GHz

Frey et al. 1997, A&A 325, 511

SVLBI @ 5 GHz: dramatic change in jet direction between

sub-mas and ~10 mas scale

… but:

1308+326 / 1308+328 quasar pair (14.3 arcmin separation)HALCA primary beam: 26 arcmin @ 5 GHzVLBA + Effelsberg switched between the sourcesphase reference mapping, relative astrometry with VSOP

1342+662 / 1342+663 quasar pair (4.8 arcsec separation)sources lie within the primary beam of HALCA & VLBA antennasit 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 VLA @ 1.6 and 5 GHzof sources with sufficiently high correlated polarized flux density

good perspectives for next-generation SVLBI

Kemball et al. 2000, PASJ 52, 1055

0235+164

a highly variable BL Lac

VSOP @ 5 GHz:the highest brightnesstemperature measured with VSOPTB > 5.8 1013 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, S5>1.3 Jy, b>10) sub-sample for SVLBI: Scorr>0.4 Jy on ground baseliness

2200+420 (BL Lac) @ 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 TB>1012 K relation between high TB 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 (S5>0.95 Jy, >–0.45, b>10),289 sources sufficiently compact for VSOP @ 5 GHz

~half of the data sets reduced, even more observed

rest-frame brightness temperature (TB) distribution shows apparent violation of inverse Compton limit (~1012 K) relativistic beaming is common

VSOP proposals, observations and data reduction

• open proposals; deadlines: 1 February, 1 June & 1 October• all info at: www.vsop.isas.ac.jp/obs/AO.html• 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: e-mail 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 VSOP-2 is beingis beingproposedproposedat ISASat ISASin Japanin Japan

• 10 increase over VSOP sensitivity• 20-40 000 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)

http://arise.jpl.nasa.gov/

• 5 ground-based resolution (max. 10-20 as) • 50 VSOP sensitivity• 40-50 000 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 ?

..