Title  High resolution imaging of radio hot spots
Pi     C. Carilli
Time   32 hrs

1.6.1: Name -- High resolution imaging of radio hot spots
    Authors: C. Carilli

2. Science goal: We will perform high resolution imaging at 100, 220,
and 650 GHz of the radio hot spots, and jets, of the archtype powerful
radio galaxies Cygnus A and Pictor A.  These data, combined with VLA
images at 8, 22, and 43 GHz, will provide the definitive test of
particle acceleration and loss mechanisms in the hot spots (=terminal
jet shocks) of powerful radio galaxies. The required sensitivities and
dynamic ranges are extrapolated from existing 43 GHz images based on
reasonable physical models for first order Fermi acceleration, and
synchrotron radiative losses, at terminal jet shocks (Carilli et
al. 1999, AJ 118, 2581; Perley et al.  1997, A&A, 328, 12). In
particular, the 650 GHz imaging is in the critical range where an
exponential cut-off is expected due to radiative losses during the
finite shock crossing time of the electrons. These observations will
delineate in detail the regions of most active particle acceleration,
and can be used to determine hot spot magnetic field strengths and
relativistic particle energy densities, independent of minimum energy
assumptions. Observations of the inner jets will constrain particle
acceleration processes along the jet, thought to occur in oblique
(weak) shocks within the jets. Resolution must be matched to that of
the VLA observations = 0.2".

3. Number of sources: 2

4. Coordinates:

  4.1. 1957+4035,  0518-4548

  4.2. Moving target: no

  4.3. Time critical: no

5.  Spatial scales:

  5.1. Angular resolution: 0.2"

  5.2. Range of spatial scales/FOV: 0.2" to 8"

  5.3. Single dish: no

  5.4. ACA: no

  5.5. Subarrays: no

6. Frequencies:

  6.1. Receiver band: Band 3 -- 100 GHz  in Configuration A
                      Band 6 -- 220 GHz  in Configuration B/C
                      Band 9 -- 650 GHz  in Configuration D

  6.2. Lines and Frequencies

  6.3. Spectral Resolution (km/s)

  6.4. Bandwidth or spectral coverage: standard continuum

7. Continuum flux density:

  7.1. Typical value: >= 1 mJy/beam at 100 GHz
                      >= 0.5 mJy/beam at 250 GHz
                      >= 0.1 mJy/beam at 650 GHz

  7.2. Continuum peak value:
      Hot spots:  45 mJy/bm at 100 GHz
                  26 mJy/beam at 250 GHz
                  15 mJy/beam at 650 GHz
      Cores:  0.5 to 1 Jy

  7.3. Required continuum rms:
                  0.01 mJy/bm at 100 GHz
                  0.02 mJy/beam at 250 GHz
                  0.06 mJy/beam at 650 GHz

  7.4. Dynamic range in image: 5000

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: due to small PB, each track will
cycle through 3 pointing positions = 2 hot spots + core.
  1 track (+/- 2hr) at 100  x 2 sources
  1 track (+/- 2hr) at 250  x 2 sources
  2 track (+/- 2hr) at 650  x 2 sources

11. Total integration time for program: 32 hr

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Review Jean Turner: This multifrequency study of prototypical radio
galaxies is well justified, the sources are classic, and there is good
motivation for going to high (650 GHz) frequency where break in
spectrum is anticipated. Scope is also good; these are two sources in
which a detailed, multiwavelength and concentrated study can be very
productive.

Technical aspects are fine, resolution to match VLA. 
Integration times are okay, agree with proposal, but are a little
arbitrary. Could use more time at 650 GHz relative to 100 GHz, but
total request is about right for this project. 



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Review v2.0:
 
1.6.1 High resolution imaging of radio hot spots (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.