Irham Andika

Irham Andika  (Indonesia)

andika @

The Search for Highest-Redshift Quasar by Using Euclid and other Surveys

Active Galactic Nuclei (AGN) in general might be centrally involved both in the regulation of star formation in massive galaxies, e.g. for the truncation and suppression of star formation in elliptical galaxies, as well as may play a role in reionization of the intergalactic medium at redshifts 6 - 10. It is therefore centrally important to understand the formation of these black holes in the early universe and to understand their growth mechanisms, environments, and general conditions. So far, a substantial population of luminous AGN has been discovered by various surveys out to z = 6.4. Beyond this redshift, the currently known number of AGN is very small. On the other hand, the black hole masses derived for AGN at z ~ 6 suggest that a substantial number of massive black holes must already have existed at earlier times. To find these early AGN is therefore paramount for progress in this field.

My project has two parts:

1) Preparation of searching for high-z AGN in data from the ESA Euclid mission, that will launch in 2021. Euclid will provide near-infrared photometry data of unprecedented depth (24 mag for point sources at S/N = 5), high spatial resolution visible data, complementary ground-based data to a similar depths. This project would prepare the search for these AGN in Euclid photometry catalogs, using parts of the Euclid simulation pipeline, and then applying statistical methods to select AGN candidate samples and infer their purity and contamination by other sources, as the basis for later follow-up observations.

2) Application of search strategies to other survey data sets available in the community. There are numerous ground-based optical and near-infrared imaging surveys containing a great number of distant AGN. Most recently, among the new surveys that can be explored are the Decals survey in the North and the first public release of the Dark Energy Survey in the South. Complementing these optical/near-infrared surveys are new radio surveys, in particular from the LOFAR low-frequency array. Candidates selected in these surveys will be followed-up with various 2 - 4 m telescopes and any remaining AGN candidates will be confirmed with observations on 4 - 8 m telescopes. Newly discovered AGN will be the targets of dedicated observations to characterize the black hole, the accretion rate, and the galaxy hosting the AGN.

Supervisor:   Knud Jahnke  (MPIA)

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