｜早期宇宙中的小红点：活动星系核、星系，还是两者兼有？
Little Red Dots in the Early Universe: AGN, Galaxy, or Both?
The launch of JWST has revolutionized the picture of the early universe in many aspects. Among its discoveries, the identification of a class of compact, extremely red objects has been particularly intriguing. These objects are characterized by point-like morphology and red colors from observed-frame ~2-5 μm, earning them the moniker “Little Red Dots” (LRDs). LRDs exhibit a unique “v” shape SED that is red in the rest-frame optical and blue in the UV, which are hard to be simultaneously described by galaxy-only or AGN-only models. They are found to be ubiquitous from redshifts z~4 up to z~9. There are lots of controversies about the nature of the LRDs. It is widely accepted that AGNs at least contribute part of the SED of LRDs, which is supported by the generally observed broad Balmer lines and compact sizes. However, there is evidence that contradicts the AGN scenario, such as the X-ray weakness, prominent Balmer break, and the flat mid-IR SED observed in some LRDs. Many AGN-galaxy hybrid models are invoked to explain the SED of LRDs. In this talk, I will give an observational overview of the LRDs. Then, I will introduce our recent systematic investigation of LRD variability and discuss the prospects of CSST in this field.
