I am a scientist-astronomer at the National Radio Astronomy Observatory (NRAO). When I joined NRAO in 2007, I primarily worked on the scientific-astronomical commissioning of the Expanded Very Large Array (EVLA). The project was concluded in Fall 2012, and the array was named the Karl G. Jansky Very Large Array (VLA) to honor the founder of Radio Astronomy. The VLA is the world's dominant cm-wavelength radio telescope and most sensitive interferometer operating between 1 and 50 GHz. Before joining NRAO in 2007, I was an astronomer at the world's largest radio-radar telescope, the 305-m (1000 ft) Arecibo Radio Telescope of the National Astronomy and Ionosphere Center (NAIC). Arecibo's 900 ton platform collapsed on Dec. 1, 2020 (video), bringing an end to a very productive scientific journey that spanned 57 years. I personally used this remarkable telescope for two decades as a single dish radio telescope and as an element in VLBI arrays. I will for sure miss it!

My research is focused on high angular resolution radio observations of extragalactic objects known as LIRGs (Luminous Infrared Galaxies) and ULIRGs (Ultra Luminous Infrared Galaxies), to study both the structure and the kinematics of the central regions in these galaxies. This research includes imaging of these galaxies in radio continuum, in HI 21 cm absorption, and in OH 18 cm megamaser emission. For this research, and in order to study the nuclear active regions of these galaxies at very high spatial resolution, I mainly use the Very Long Baseline Array (VLBA) of the NRAO. However, the radio emission from these IR galaxies is very weak. Therefore, in order to have successful observations, the Very Large Array(VLA) of the NRAO, with its twenty seven 25-meter antennas, participates in these sensitivity limited observations. In some of these observations, the giant 305-meter Arecibo radio telescope was used along with both the VLBA and the VLA.

The enhanced observational capabilities of the VLA opened led us to discover the Zeeman effect in three Class I methanol maser transitions: at 25, 36, and 44 GHz, and in two Class II methanol maser transistions at 38.3 and 38.5 GHz. Visit my publications page to check the discovery and the follow-up papers on this topic (through the NASA ADS).

I am also involved in the COSMOS HI Large Extragalactic Survey (CHILES). This is a blind HI survey to detect 21 cm neutral hydrogen emission up to a redshift of 0.45 using the new capabilities of the VLA. The observations of the survey (1000 hours) have concluded already. In 2016, and using the first 178 hours of the VLA CHILES observations we have already broken the record of the highest redshift HI 21 cm detection in emission (see the NRAO press release on this topic).

I am actively involved in VLA and sensitive VLBI imaging of the radio continuum emission from very high redshift quasars, both radio-loud and radio-quiet. These quasars are believed to be near the epoch of re-ionization, i. e., when the first stars and galaxies started to form (less than 1 billion years after the Big Bang). The current redshift record for a radio-loud quasar, which has also been detected and imaged with VLBI, is z=6.82 (see the NRAO press release on this topic). We also expanded this type of work to sub-millimeter galaxies (SMGs) at z~2-3 to study and determine their nuclear power sources (AGN vs. starburst).

You can reach me by sending an email to emomjian (append @nrao.edu)

Last updated: Wednesday, 04-Sep-2024 22:13:57 MDT