CARA Science: SPIFI

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Summary

The South Pole Imaging Fabry-Perot Interferometer (SPIFI) is an imaging Fabry Perot for use in the far-infrared and submillimeter (200, 350, 450 micron) windows available to the AST/RO telescope at the South Pole. SPIFI employs a 5x5 element array of monolithic silicon bolometers cooled to 60 mK with an adiabatic demagnetization refrigerator (ADR). The array is fed by Winston cones with 1.2 /D entrance apertures set in a rectangular grid separated by 1.4 /D in the focal plan, resulting in a 315''x315'' field of view on AST/RO. SPIFI's resolving power is fully tunable from R ~ 300 to 10,000 and its resolving power and sensitivity are uniform over the entire field of view. SPIFI's sensitivity is consistent with the background limit at all resolving powers.

The primary science drivers for SPIFI are mapping in the CO (7-6) (371 micron) rotational line, and the [CI] (J = 2 - 1) (370 micron) fine structure lines in the Galactic Center, nearby galaxies including low metalicity dwarfs, distant starburst galaxies, and ultraluminous infrared galaxies. We also hope to detect redshifted [CII] line emission from galaxies at z > 1 with SPIFI. These lines trace the physical conditions of the gas associated with regions of active star formation and can be used to probe the hardness and strength of the ambient far-UV radiation fields.

Results

SPIFI had first light on the James Clark Maxwell Telescope (JCMT) on Mauna Kea in April 1999. (see Figures 2 and 3). There were 15 pixels installed in the array, of which 13 were working. The resolving power employed corresponded to a velocity resolution of about 70 km/s Since this was the first run, the SPIFI team was rather conservative and focused on the brighter and easier to calibrate CO (7-6) line. The SPIFI system sensitivity was quite good. No evidence was found for excess noise at the telescope and the sensitivity was equivalent to a double side-band receiver temperature of 100 K.

A second test run is scheduled for the JCMT from September 14 to 27, 1999. The final pixels are installed in the array, so it is expected that the full 5 by 5 array will be operational. The reimaging lens system has also been improved to increase the sensitivity per pixel.

Pictures

For more information

See the group's website at http://astrosun.tn.cornell.edu/research/projects/spifi.html

SPIFI is based at Cornell University. For more information, conatct Gordon Stacey, stacey@astrosun.tn.cornell.edu .