Title  mm VLBI imaging of IDVs
Pi     C. Carilli
Time   50 hrs
5.1.3: Name -- mm VLBI imaging of IDVs
    Authors: C. Carilli

2. Science goal: We propose VLBI imaging using the Pacific array (see
1.6.3) at 220 GHz of a representative sample of IDVs (Intra-Day
Variability).  These data will probe to scales of 20uas, and test
models for coherent emission mechanisms to explain the very high
brightness temperatures inferred from the ISS (Maquart et al. 2000 ApJ
528, 623), thereby constraining physical conditions in the jet, and
perhaps study aspects of the accretion disk via the induced Compton
scattering mechanism(?).

3. Number of sources: 5

4. Coordinates:

  4.1. Any

  4.2. Moving target: no

  4.3. Time critical: no

5.  Spatial scales:

  5.1. Angular resolution: 20uas

  5.2. Range of spatial scales/FOV: 20 uas -- 200 uas

  5.3. Single dish: no

  5.4. ACA: no

  5.5. Subarrays: no

6. Frequencies:

  6.1. Receiver band: Band 6 -- 220 GHz  in Configuration D or E,
       phased-array

  6.2. Lines and Frequencies

  6.3. Spectral Resolution (km/s)

  6.4. Bandwidth or spectral coverage: 1 GHz x 2pol (set by VLBI
recorder)

7. Continuum flux density:

  7.1. Typical value:

  7.2. Continuum peak value: <= 2 Jy

  7.3. Required continuum rms:
        ALMA - HHT baseline, 10 min rms = 0.7 mJy
        ALMA - LMT baseline, 10 min rms = 0.2 mJy

  7.4. Dynamic range in image: 1e3

8. Line intensity:

  8.1. Typical value:

  8.2. Required rms per channel:

  8.3. Spectral dynamic range:

9. Polarization: yes

10. Integration time per setting:
  5 sources at 5 hrs per source

11. Total integration time for program: 50 hr

note: this is not a monitoring project (at least initially), nor is it
triggered since getting the source during an IDV event is not critical
for the high frequency VLBI imaging.

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Review Jean Turner:
Technical: I have to take Chris's numbers on faith since they involve
other telescopes and VLBI. They seem very reasonable given the ALMA
sensitivities.



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Review v2.0:
 
1.6.6. mm VLBI imaging of IDVs (Carilli)

Not revised since DRSP 1.1. Nothing needs to be added to the review
back then, no severe impact through reduction to 50 antennas, no need
for ACA.  I'm not an expert in this, but I think there is still a
debate going on if this effect is source intrinsic or not.  If not,
the scientific interest in this topic may disappear or get much
weaker.