APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Ecaterina Leonova (University of Amsterdam)
Title: Galactic Alliance. Ubiquitous Overdensities around Lyman Alpha Emitters in the First Billion Years of the universe with the JWST FRESCO Survey
Date (JST): Tue, Jul 09, 2024, 11:00 - 12:00
Place: Balcony B
Abstract: After the Dark Ages, the Epoch of Reionization (EoR) marked the emergence of light in the universe and signified its final transition. Over the last few decades, the study of the EoR has become a major focus in the high-redshift field. Lyman alpha emitters (LAEs) are utilized to investigate the EoR, but their detection becomes challenging beyond redshift 7 when the universe is predominantly neutral. Some high-redshift LAEs are detected, possibly because Lyman alpha photons stretch inside ionized regions due to cosmic expansion, avoiding absorption by neutral hydrogen. LAEs alone may not create sufficiently large ionized bubbles; instead, they likely exist in overdense regions where neighboring galaxies contribute to ionization, assisting in Lyman alpha detection.
We study the surroundings of known Lyman alpha emitters (LAEs) identified at redshifts 7-8 in the GOODS-N and GOODS-S fields. We use data from the JWST FRESCO program to identify OIII-emitting companions around these LAEs and find that these LAEs have companions, and some of these companions are located in significant overdensities. Moreover, we compare the intrinsic properties of Lyman alpha and OIII emitters and conclude that, in general, they are not different. This leads to the conclusion that the visibility of Lyman alpha lines is more likely to be explained by overdensities around them.