JWST, ALMA, and Keck Spectroscopic Constraints on the UV Luminosity Functions at z~7-14: Clumpiness and Compactness of the Brightest Galaxies in the Early Universe

We present the number densities and physical properties of the bright galaxies spectroscopically confirmed at z7-14. Our sample is composed of 53 galaxies at zₛpec7-14, including recently-confirmed galaxies at zₛpec=12. 34-14. 32 with JWST, as well as new confirmations at zₛpec=6. 583-7. 643 with -2410. The UV luminosity functions derived from these spectroscopic results are consistent with a double power-law function, showing tensions with theoretical models at the bright end. To understand the origin of the overabundance of bright galaxies, we investigate their morphologies using JWST/NIRCam high-resolution images obtained in various surveys including PRIMER and COSMOS-Web. We find that 70\% of the bright galaxies at z7 exhibit clumpy morphologies with multiple sub-components, suggesting merger-induced starburst activity, which is consistent with SED fitting results showing bursty star formation histories. At z10, bright galaxies are classified into two types of galaxies; extended ones with weak high-ionization emission lines, and compact ones with strong high-ionization lines including NIV]1486, indicating that at least two different processes (e. g. , merger-induced starburst and compact star formation/AGN) are shaping the physical properties of the brightest galaxies at z10 and are responsible for their overabundance.