August 7 Wed 14:30-15:30
ALMA-J Seminar
hybrid; Room 102 in ALMA Building and Zoom
詳細は下記からご覧ください。
=============== August 7 Wed===============
Seminar: ALMA-J Seminar
Date and time: August 7th, 2024 (Wed.), 14:30-15:30 JST
Place: ALMA Building Room 102 / Zoom (hybrid)
Speaker: Qi-Ning Hsu
Affiliation: National Tsing Hua University
Title: Submillimeter Extragalactic Background Light and Galaxy Number Counts
Abstract:
The extragalactic background light (EBL) is the cumulative radiation from beyond
our Milky Way galaxy and is essential for understanding cosmic history. However,
the origin of the EBL at submillimeter wavelengths, particularly near the peak
of the cosmic infrared background, remains uncertain. To investigate this, we
conducted galaxy number counts to determine the origin of the 450 micron EBL
using SCUBA-2 observations in 10 massive galaxy cluster fields. The strong
gravitational lensing provided by these clusters allows us to construct
ultra-deep number counts, over ten times deeper than those obtained from blank
fields. By carefully accounting for possible systematics, we achieved significant
counts down to ~0.1 mJy. Comparing our measurements to those made by the COBE
satellite, we found that at the sub-mJy level, the 450 micron EBL is entirely
resolved. Thus, we present the first evidence that discrete sources, likely of
extragalactic origin, fully contribute to the 450 micron EBL, with about half
of it originating from sources with sub-mJy flux densities. In this talk, I will
introduce the submillimeter EBL, describe how we conduct galaxy number counts in
the submillimeter regime, and present my recent works.
Organizers : Kshitiz Mallick, Yuichi Matsuda