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최신연구

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Intracluster light is already abundant at redshift beyond unity
작성일
2023.01.05
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천문우주학과
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Intracluster light is already abundant at redshift beyond unity

초기 은하단에서 풍부한 양의 은하단내광 검출

Hyungjin Joo & M. James Jee


Intracluster light (ICL) is diffuse light from stars that are gravitationally bound not to individual member galaxies, but to the halo of galaxy clusters. Leading theories predict that the ICL fraction, defined by the ratio of the ICL to the total light, rapidly decreases with increasing redshift, to the level of a few per cent at z > 1. However, observational studies have remained inconclusive about the fraction beyond redshift unity because, to date, only two clusters in this redshift regime have been investigated. One shows a much lower fraction than the mean value at low redshift, whereas the other possesses a fraction similar to the low-redshift value. Here we report an ICL study of ten galaxy clusters at 1 z 2 based on deep infrared imaging data. Contrary to the leading theories, our study finds that ICL is already abundant at z 1, with a mean ICL fraction of approximately 17%. Moreover, no significant correlation between cluster mass and ICL fraction or between ICL color and cluster-centric radius is observed. Our findings suggest that gradual stripping can no longer be the dominant mechanism of ICL formation. Instead, our study supports the scenario wherein the dominant ICL production occurs in tandem with the formation and growth of the brightest cluster galaxies and/or through the accretion of preprocessed stray stars.

These are Hubble Space Telescope images of two massive clusters of galaxies named MOO J1014+0038 (left panel) and SPT-CL J2106-5844 (right panel). The artificially added blue color is translated from Hubble data that captured a phenomenon called intracluster light. This extremely faint glow traces a smooth distribution of light from wandering stars scattered across the cluster. Billions of years ago the stars were shed from their parent galaxies and now drift through intergalactic space.

Credits: NASA, ESA, STScI, James Jee (Yonsei University); Image Processing: Joseph DePasquale (STScI)


https://ui.adsabs.harvard.edu/abs/2023Natur.613...37J/abstract

저자명
Hyungjin Joo, M. James Jee