Submm Observations of High-Redshift Quasar Candidates with Atacama Large Millimeter Array
Ekaterina Koptelova1*, Chorng-Yuan Hwang1
1Graduate Institute of Astronomy, National Central University, Taoyuan, Taiwan
* Presenter:Ekaterina Koptelova,
The most distant quasars are now observed at redshift z>6.5 (less than 1 Gyr after the Big Bang). They provide important information on the ionization state of the intergalactic medium during the epoch of reionization and formation of first supermassive black holes. However, these quasars are very rare and difficult to identify by means of optical/near-infrared spectroscopy. The recent observations with Atacama Large Millimeter Array (ALMA) showed that the submillimeter spectra of high-redshift quasars exhibit many emission lines originating in quasars’ hosts. These lines, e.g., CO rotational transitions, provide an alternative way to identify and to measure the redshifts of the most distant quasars. Unlike the UV Lyα line of quasars, the CO emission lines do not suffer from absorption by neutral hydrogen. Moreover, the CO transitions are closely spaced in frequency allowing for robust redshift measurements. Here, we present our results of ALMA Band 3 spectroscopy of high-redshift quasar candidates selected from the PanSTARRS1 survey.

Keywords: High-redshift quasars, Surveys, ALMA