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Project Progress

GCA Co-Investigator Prof. William M. Irvine and colleagues at the University of Massachusetts have been using a unique new broadband receiver to measure the spectra of external galaxies in the 3mm wavelength region. The so-called Redshift Search Receiver (RSR) has an instantaneous bandwidth of 36 GHz, covering the frequency range from 74 to 110.5 GHz. It is ultimately intended for use on the Large Millimeter Telescope (LMT; see below); however, until the LMT is completed, the receiver is being tested at the Five College Radio Astronomy Observatory’s (FCRAO’s) 14-meter telescope, operated by the University of Massachusetts. This provides the opportunity to simultaneously observe most of the 3mm spectrum of a galaxy, and hence to measure the molecular emissions in this band. Early results indicate that there are striking differences in the chemical composition of interstellar organic material in different galaxies (Narayanan et al., 2008). Theoretical work suggests that the relevant effects include differences in both ultraviolet and X-ray environments, and in the importance of shocks.

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Administrative Activities Related to Astrobiology:

Irvine continues as elected Vice-President of the International Astronomical Union’s Commission 51, Bioastronomy. He is working with Commission 51 President, Alan Boss, and with Antonio Lazcano, the President of ISSOL-The International Astrobiology Society, to organize a joint international meeting in 2011. This conference would be a major venue for astrobiology discussion and interaction.

Irvine chaired the Scientific Organizing Committee for the conference Bioastronomy 2007, sponsored by IAU Commission 51 and held in San Juan, Puerto Rico, in July 2007. These activities included establishing a general outline for the conference, identifying and contacting invited speakers, correlating all significant decisions with the rest of the Scientific Organizing Committee, reading all 175 submitted abstracts and tentatively distributing them by conference session, consulting on an invited public lecture and on other evening or excursion activities, and planning the detailed conference schedule. The conference was considered to be very successful, with some 200 scientists attending from 23 countries.

Irvine was also a member of the Scientific Organizing Committee for International Astronomical Union Symposium 251, “Organic Matter in Space”, held in Hong Kong, February 18-22. His suggestions led to the inclusion of important presentations relevant to astrobiology, in such fields as planetary atmospheres and interstellar chemistry.

Facilities:

The Large Millimeter Telescope (LMT) is a joint project of the University of Massachusetts Amherst and the Instituto Nacional de Astrofisica, Optica y Electronica (INAOE) in Tonantzintla, Puebla, Mexico. The LMT will be the largest single-dish telescope in the world operating at short millimeter wavelengths when it is completed in 2008-09. It will be a powerful instrument for various fields within astrobiology, including the study of the chemistry and physics of comets and other primitive bodies in the solar system, planetary and satellite atmospheres, and organic molecules in the interstellar medium of the Milky Way and other galaxies. Irvine continues as a member of the Science Working Group for LMT. In addition, he is a Special Assistant to the Vice-Provost for Research at the University of Massachusetts Amherst, with responsibility for promoting closer cooperation between the US and Mexican teams working on the project. Irvine will insure that astrobiological research opportunities for the telescope are appreciated and taken into account in plans for instrumentation and operation.

At this time the telescope alidade and back-structure are complete, three of the five rings of surface panels have been installed, the telescope drive system has demonstrated the ability to track an astronomical source, and most of the associated facilities (electrical, communications, etc.) are in place. The major challenges are bringing the surface into the specified figure (rms), procuring and testing the outer two rings of surface panels, and installing capable actuators for the active surface. The initial instrumentation for the telescope is mostly complete: SEQUOIA, a 32-element heterodyne array for observations at 3-mm; AzTEC, a 144-element bolometer array for observations at 1 and 2-mm; the Redshift Search Receiver described above (36 GHz instantaneous bandwidth) at 3mm wavelength, intended to measure the redshift of distant galaxies and the shape of planetary absorption lines; and a 4-element heterodyne SIS receiver for operation at 1-mm. SEQUOIA, AzTEC and the Redshift Search Receiver have been extensively tested and used on smaller radio telescopes, and the 1-mm receiver is under construction.

First light at 3mm, utilizing the inner 3 rings of panels (providing a reflector diameter of 32 meters), is planned for fall 2008. Commissioning activities will include setting the surface with the aid of holography, tuning the active surface for gravitational and thermal effects, determining the telescope pointing, implementing the full servo-system, integrating the instruments into the system, and initial astronomical observations.

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Outreach:

A temporary Visitors’ Center for the LMT has been established in Cuidad Cerdan, a city about 18 km from the base of the mountain where the LMT is cited. Displays about the telescope are presented and described at the annual fall fair in Cuidad Cerdan.

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Future Plans:

Observations of comets:

Although intended primarily for extragalactic observations, the AzTEC array is a powerful mm-wavelength camera that can be used for mapping dust emission from cometary comae. It has now been tested and used extensively in an ambitious two—year visiting instrument program at the Atacama Submillimeter Telescope Experiment (ASTE). ASTE is a Japanese-run, 10-m diameter telescope located on Pampa La Bola, near Cerro Chajnantor — the location for the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile. The AzTEC/ASTE team is a multi-national group composed of astronomers from UMass, Mexico, the National Astronomical Observatory in Japan (NAOJ) and the University of Tokyo. There is an agreement that AzTEC will remain at the ASTE telescope through 2008 and then go to the LMT to begin 2mm wavelength operations from the much larger dish.

If a bright comet appears while AzTEC is on the ASTE, an effort will be made by the UMass team to map the coma in dust emission, which will provide information on particle size and on the gas/dust ratio, as a function of position in the coma.