VSOP-2 PLS: ν>8 GHz Yuri Kovalev Humboldt fellow, MPIfR, Bonn; Astro Space Center, Lebedev Physical Institute, Moscow 14 May 2008 VSOP-2 workshop, Bonn
Outline What are the main goals of the VSOP-2 PLS? (more on that: Dr. Gabanyi) Large VLBI surveys: What has been already achieved Are new pre-launch surveys needed to achieve VSOP-2 goals? 8 GHz 22 GHz 43 GHz (PLS: VERA/KVN, Dr. Lee talk) 86 GHz
Reasons to have VSOP-2 PLS Phase-reference calibrators needed for sure. Requirements from possible VSOP-2 surveys (should be determined by proposed VSOP-2 KSP surveys): e.g., completeness, compactness, etc. I would expect VISC-2 to comment on it at some (early) point.
8 GHz X-band VSOP-2 frequency band
Search for Compact Extragalactic Sources with VLBA and RATAN-600 Main goals of the VLBA Calibrator Survey (VCS): Search for compact sources to be used in VLBI experiments with phase referencing; absolute position determination with mas-accuracy Astrophysical application: construction of complete correlated-flux-density-lmited sample and its analysis References and people involved: Beasley et al. (ApJS, 2002), Fomalont et al. (AJ, 2003), Petrov et al. (AJ, 2005, 2006, 2008), Kovalev et al. (AJ, 2007)
ICRF/VCS: sky coverage
ICRF/VCS: sky coverage and probability to find a calibrator above -40 o declination
VCS: sample properties A complete correlated flux-density-limited sample of sources with total VLBA flux density at 8 GHz > 200 mjy, declination > -30 degrees, Galactic latitude b > 1.5 degrees, flat continuum radio spectrum (flatter than -0.5) is formed. About 1700 sources in total.
Next step(s) Probability to find a calibrator 1. The calibrator coverage south of declination -50 o will be increased by the Australian LBA survey started in February 2008, this campaign will observe about 500 candidate sources (P.I.: L. Petrov). 2. Should we go deeper in the Northern sky? If yes, how much deep? Recommendation from VISC-2/VSOG-2 is required.
22 GHz K-band VSOP-2 frequency band
Recent achievements: 22 GHz ICRFext at 22 and 43 GHz: Lanyi et al. observed several hundred compact extragalactic radio sources at 22 and 43 GHz. Goal: extention of the ICRF to higher frequencies. VERA FSS / VLBA GaPS at 22 GHz: VERA Fringe Search Survey has selected candidates for a VLBA follow up in the galactic plane (Petrov et al. 2007). Has proven to be successful approach but higher sensitivity is strongly desirable. VLBA follow-up is being reduced right now.
Current situation + plans: 22 GHz All strong VCS selected at 8 GHz (>1000) sources are observed by VERA right now: fringe search observing strategy. Detections to be followed-up by VLBA. Project is done in collaboratrion with H. Kobayashi, T. Jike, M. Honma, K.M. Shibata, T. Hirota.
43 GHz Q-band VSOP-2 frequency band VERA/KVN: wait until next talk
90 GHz W-band Non VSOP-2 frequency band
GMVA: 90 GHz GMVA survey of 127 sources was analyzed and published recently by Lee et al. (2008). To be discussed in Dr. Lee s talk. A new deeper MPI-led 3 mm GMVA survey is being planned in order: to establish a complete sample for surveying with VSOP-2 to provide matched resolution GMVA images to VSOP-2 to identify sources suitable for 22 and 43 GHz studies with VSOP-2
PLS surveys with VLBI (particularly, VLBA): political, regional, and sensitivity issues Political issues: a significant fraction of observing time is required. Is VLBA ready to grant this time? Can we achieve our goals without VLBA? Sensitivity issue: how critical is it to be able to use 4Gbps/Mark5C with VLBA? Should we wait until it becomes available? Should/can we help the sensitivity upgrade to happen sooner? Southern hemisphere: options at 43 GHz?? Support/advice from VISC-2 would be helpful.
Thank you April June 11, 10, 2005 Arecibo Observatory Library Colloquium NASA GSFC
VCS complete sample: compactness About 1000 sources show compactness >0.7 5 December 2007 VSOP-2 Symposium
Core Dimensions Typical dimensions of the core: <0.3 mas (<3 pc) along the major axis, <0.1 mas (<1 pc) along the minor axis. Kovalev et al. (2005) 5 December 2007 VSOP-2 Symposium
Unification scheme Annotated by M. Voit 5 December 2007 VSOP-2 Symposium
MOJAVE Program Monitoring Of Jets in Active Galaxies with VLBA Experiments 4 year successor to VLBA 2 cm Survey observations spanning May 2002 Dec 2005 New aspects/advantages: linear and circular polarization imaging of a complete AGN sample of 133 sources supporting single-dish radio observations decade-long baselines for studying long-term jet evolution PI: Matt Lister First epoch LP & CP results: Lister & Homan (2005), Homan & Lister (2006) http://www.physics.purdue.edu/astro/mojave/ 5 December 2007 VSOP-2 Symposium
MOJAVE-2 Program Started Jan 2006, 1 epoch per month, large VLBA program approved until May 2007. 4-frequency (8.1, 8.4, 12, & 15 GHz) full Stokes study of about 190 AGN including the complete MOJAVE sample, all EGRET sources north of -20 degrees, low redshift AGN New aspects: Faraday rotation measuremens, spectral study of compact jets, core shifts. http://www.physics.purdue.edu/astro/mojave/ 5 December 2007 VSOP-2 Symposium
Radio Galaxy M87 (redshift 0.0044) The most compact feature appears to remain constant although the larger scale jet structure shows changes by up to a factor of two in correlated flux density. This unusual behavior, which was first noted by Kellermann et al. (1973), is remarkable in that the dimensions of this compact stable feature are only of the order of ten light days or less. We note that this weak (<0.2 Jy), but stable feature in the center of M87 may be closely associated with the region where relativistic particles are accelerated. Kovalev et al. (2005) 5 December 2007 VSOP-2 Symposium
Flux Density, Jy Radio Continuum Spectra Types Frequency, GHz Kovalev et al. (2002) 5 December 2007 VSOP-2 Symposium
Flux Density, Jy Flaring Variability of Compact Jets Frequency, GHz Kovalev et al. (2002) 5 December 2007 VSOP-2 Symposium