2024 Project Description

Searching for Luminous Heavily Obscured AGN in all-sky Mid-infrared and X-ray surveys

Supervisors

Bovornpratch Vijarnwannaluk, Wei-Hao Wang, Chian-Chou Chen (TC)
Find out more about supervisors on ASIAA website

Task Description and Goals

Active Galactic Nuclei (AGN) are supermassive black holes in the phase of rapid mass growth from gas accretion onto the black hole. It has been theorized that they are an important part of the evolution of massive galaxies and can be triggered by the large amount of gas which are funnelled into the central part of the galaxy during galaxy mergers. However, during this phase, the large amount of gas and dust during mergers can obscure most of the optical emission of AGNs from telescopes. Moreover, It is difficult to produce a statistically significant sample of AGN in galaxy mergers due to the rarity of galaxy mergers and luminous AGN compared to typical galaxies. Thankfully with the launch of recent all-sky X-ray and infrared probes, it may be possible to identify highly luminous AGN by leveraging the large survey areas. By examining the optical and near-infrared images of the AGNs, a sample of merger-triggered AGNs could be constructed for statistical discussion. For the ASIAA summer student program, the student will use the catalogue data from the WISE all-sky survey and the eROSITA Public Data release 1 to produce a catalogue of luminous obscured AGN triggered by galaxy mergers after limiting the survey area to that covered by optical or near-infrared imaging datasets. The student is expected to perform the following task within the 8 weeks of the program.

1. Review the important literature and concepts on the topic of AGN triggering by galaxy mergers for the final presentation.
2. Produce a sample of AGN using Infrared AGN selection or using available samples of infrared-selected AGN and identify AGN activity by cross-matching with the eROSITA DR1.
3. Reduce the sample by limiting the survey area to that covered by optical or near-infrared imaging surveys and deep multiwavelength surveys.
4. Identify possible obscured AGN using optical-infrared colours or compare it with X-ray emission.
5. Identify galaxy merger candidates with the imaging surveys systematically or by eye.
6. Discuss the AGN properties of unobscured AGN, obscured AGN, and merger-triggered candidates. Discuss the possible selection effects and statistical properties of the sample and perform additional statistical analysis compared with the literature.

Required Background

Basic knowledge of astronomy and physics Basic knowledge of Python programming, and Linux usage, is desirable. Good English proficiency in communication and writing.