In this talk, I will present analysis of a spectroscopic sample of 23 broad-line AGNs (BLAGNs) at 3≲z≲6 selected using F322W2+F444W NIRCam/WFSS grism spectroscopy of the central 100 arcmin2 area of the NEXUS survey. Among these BLAGNs, 15 are classified as Little Red Dots (LRDs) based on their rest-frame UV-optical spectral slopes and compact morphology. The number density of LRDs is ∼1e-5 cMpc−3, with a hint of declining towards the lower end of the probed redshift range. These BLAGNs and LRDs span broad Hα luminosities of ∼10^{42.2−43.7} erg s^−1, black hole masses of ∼1e6.3−1e8.4 M⊙, and Eddington ratios of ∼0.1−1 (median value 0.4), though the black hole mass and Eddington ratio estimates carry large systematic uncertainties. Half of the LRDs show strong Balmer absorption, suggesting high-density gas surrounding the line-emitting region. We detect extended (hundreds of parsecs) rest-frame UV-optical emission from the host galaxy in the majority of these LRDs, which contributes significantly or even dominantly to their total UV emission. This host emission largely accounts for the peculiar UV upturn of the LRD spectral energy distribution. We also measure the small-scale (≲1cMpc) clustering of these BLAGNs and LRDs by cross-correlating with a photometric galaxy sample. Extrapolating the power-law two-point correlation function model to large linear scales, we infer a linear bias of 3.30^{+2.88}_{−2.04} and typical halo masses of a few ×1e11 h−1M⊙ for BLAGNs at the sample median redshift of z∼4.5. However, the inferred linear bias and halo masses of LRDs, while formally consistent with those for BLAGNs at ∼1.5σ, appear too large to be compatible with their space density, suggesting LRDs may have strong excess clustering on small scales.
BIO
Mingyang Zhuang is a postdoctoral research fellow at University of Illinois Urbana-Champaign. He obtained PhD degree in astrophysics at Peking University in 2022. He has broad research interests, including galaxy formation and evolution, coevolution of supermassive black holes and their host galaxies, AGN feedback, and interstellar medium. He is experienced in JWST NIRCam imaging and NIRSpec spectroscopy reduction and analysis. He is (co-)leading several ongoing JWST programs.
