科研之友
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摘要
We present a study of a sample of 45 spectroscopically confirmed, UV luminous galaxies at z similar to 6. They were selected as bright Lyman-break galaxies (LBGs) using deep multi-band optical images in more than 2 deg2 of the sky, and subsequently identified via their strong Ly alpha emission. The majority of these LBGs span an absolute UV magnitude range from -22.0 to -20.5 mag with Ly alpha equivalent width (EW) between similar to 10 and similar to 200 & Aring;, representing the most luminous galaxies at z similar to 6 in terms of both UV continuum emission and Ly alpha line emission. We model the SEDs of 10 LBGs that have deep infrared observations from HST, JWST, and/or Spitzer, and find that they have a wide range of stellar masses and ages. They also have high star-formation rates ranging from a few tens to a few hundreds of Solar mass per year. Five of the LBGs have JWST or HST images and four of them show compact morphology in these images, including one that is roughly consistent with a point source, suggesting that UV luminous galaxies at this redshift are generally compact. The fraction of our photometrically selected LBGs with strong Ly alpha emission (EW>25 & Aring;) is about 0.2, which is consistent with previous results and supports a moderate evolution of the IGM opacity at the end of cosmic reionization. Using deep X-ray images, we do not find evidence of strong AGN activity in these galaxies, but our constraint is loose and we are not able to rule out the possibility of any weak AGN activity.
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