Dr. Shemmer Leads 3-Year Quasar Project at Gemini Observatory | College of Science
October 11, 2018

Dr. Shemmer Leads 3-Year Quasar Project at Gemini Observatory

View the full video: Pacing High-Redshift Quasars in Perspective: a Gemini Near-Infrared Spectroscopic Survey

Located high above the clouds towers a dormant volcano towers 7,400 meters above the bottom of the Pacific Ocean. This, the tallest volcanic peak on earth, is considered sacred by the indigenous people surrounding it as the most sacred region of the benevolent spirits and the home of Poli'ahu, the deity of snow. This Hawaiian volcano is called Mauna Kea, a shortened form of Mauna Wākea which means mouth of the sky father. It is here that astronomers from around the world have crafted a tenuous agreement with the indigenous people that allows astronomers to build and maintain telescopes high above most lights and air pollution that envelope our home planet.

The following is a transcription of the video's fascinating interview between UNT's Dr. DiIulio, Director of Rafes Urban Astronomy Center, and Dr. Ohad Shemmer, the staff astronomer from the University of North Texas and the principle investigator for this three-year long program at the Gemini Observatory, one of the most far-reaching research projects ever attempted.

Dr. DiIulio: Dr. Shemmer, can you please describe what this project is about?

Dr. Shemmer: We were recently awarded 350 hours of observing time at Gemini North in Hawaii, one of the world's largest telescopes. This is to observe more than 400 distant quasars and obtain their infrared spectrum.

Dr. DiIulio: While we've heard the term quasar, can you elaborate on the nature of these objects?

Dr. Shemmer: Quasars are the most luminous persistent sources in the universe; they shine brighter than a trillion suns, and as such they serve as cosmological signposts. These cosmic powerhouses form when gases funnel towards giant black holes at the centers of galaxies.

Dr. DiIulio: What are the main goals of this project and what are the projected outcomes?

Dr. Shemmer: The Gemini observations will lead to better estimates of the masses of the quasar's black holes, their fueling rates, and their distances from earth. The results of this project will help us develop improved equations for these key properties for all quasars. The next generation of cosmological surveys will generate millions of quasar spectra, the analysis of which will greatly benefit from the prescriptions developed in this investigation.

Dr. DiIulio: Why is it important to study quasars?

Dr. Shemmer: Quasars consist of growing black holes, millions to billions of times more massive than the sun. Since quasars are thought to shape the growth of their galaxies, better understanding these sources is one of modern astronomy's major goals.

Dr. DiIulio: I can see that below the Gemini Telescope is mounted the largest infrared spectrograph in the world, why this system?

Dr. Shemmer: We need the Gemini observations because they will provide us with superb infrared spectra of these distant sources and these are needed to observe key features in the quasars' spectrum.

Dr. DiIulio: By the way, can you please explain what you can learn from an object spectrum?

Dr. Shemmer: An object's spectrum is like its fingerprint; it can tell us about the object's composition, its temperature, how fast its moving, and other key properties.

Dr. DiIulio: How would you describe the overall scope and significance of this project?

Dr. Shemmer: Some 350 hours of infrared observations of over 400 distance quasars with the Gemini Telescope in Hawaii will produce the best and largest data set of its kind. The Gemini project involves more than 20 scientists from all over the world, including key researchers in quasar science, and the results of this project will help us place distant quasars in perspective, which means we will be able to better tie the properties of these distant sources with those of the more common, nearby quasars.

The next three years should provide some exciting new information about quasars, thanks to this project and the team of scientists behind it.