Galactic Center Positronium Search

We'd like to use TripleSpec to try to detect positronium H-alpha and Paschen-gamma.
TripleSpec (cookbook from palomar) sensitivities should be ~19th mag in J band, 17th in K-band: it is more sensitive in the H-alpha line. (these numbers assume 10 minute exposures, but we are probably limited to ~18th magnitude by sky)

Proposal draft for APO 3rd quarter 2008: apo_gcprop.txt

Zero magnitudes for J and K bands are given: here
K = 666.7, J=1594
Our K sensitivity, then, is 666.7*10**(-17/2.512) = 114 microJanskys
J is 1594 * 10**(-18/2.512) = 108 microJanskys
so really the difference isn't that significant when you take into account sky background

Those measurements are for a continuum source, and they may be wrong. We also need to do these calculations for a resolved line.

Source 4 below gives an expected flux to "the best known source of annihilation in the GC direction" of F(H-alpha) = 5x10^-29 erg cm^-2 s^-1 Hz^-1 = 5 microJanskys
This source also recommends looking at GROJ1655-40, GRS1758-258

If there is any emission from a point source, then observing with APO is the right way to go. Otherwise, our only real hope is to average over a number of observations.

Task list:
  1. Pick targets: Great Annihilator? Empty region? Ask John
  2. Determine limits INTEGRAL information gives us
  3. Data mine?


Source list:
  1. Great Annihilator
  2. GROJ1655-40
  3. GRS1758-258
  4. 17 43 54.83 -29 44 42.6
  5. 16 54 00.14 -39 50 44.9
  6. 18 01 12.30 -25 44 36.0

    TripleSpec A0 calibrators
    Top choices:
    1. HD 159008,f|S|A0V, 17:32:50.71, -13:28:55.5, 7.24, 2000
    2. HD 164333,f|S|A0V, 18:00:55.98, -8:28:34.6, 10.04, 2000
    3. HD 155379,f|S|A0V, 17:12:13.62, -25:15:18.5, 6.50, 2000
    4. HD 164638,f|S|A0V, 18:03:09.84, -27:06:51.6, 10.58, 2000


    Relevant papers:
    1. INTEGRAL central radian measurements
    2. All-sky distribution of 511 keV
    3. Characteristic Lines of Positronium
    4. Proposal for detection
    5. Bally and Leventhal: Great Annihilator
    6. Search for Positronium in Great Annihilator



    For data mining: There are SINFONI integral field spectrograph Ks-band observations of the GC, which means that there should be a lot of identically-sampled spectra that can be averaged over to attempt to get at the Pa-Gamma line. Otherwise, we need to start looking at Keck/VLT/Gemini spectra; those will be the deepest.
    ESO Data Archive
    List of public (and private) SINFONI observations of GC
Cumulative Exposure Time / Instrument / Filter:
SCIENCE - SINFONI - 23 h 41 min 54 s
SCIENCE - SINFONI - H+K 29 h 15 min 33 s
SCIENCE - SINFONI - K 36 h 35 min 33 s
CALIB - SINFONI - K 0 h 0 min 20 s
ACQUISITION - SINFONI - H+K 0 h 2 min 6 s
ACQUISITION - SINFONI - K 0 h 0 min 43 s
Total 89 h 36 min 10 s