Oral Presentation
The dark halo mass of quasars at z~6 with SHELLQs
Presenter: Junya Arita (The University of Tokyo)
High-z quasars are key objects to understand an initial co-evolution of galaxies and their central supermassive black holes because their feedback has a significant impact on the host galaxies. To verify the feedback models, dark matter halo (DMH) mass in the early universe is the important physical quantity. The DMH mass can be estimated by clustering analysis, but it requires a sufficient high number density in the quasar sample and has thus been limited to application at z > 4. However, the number density is rapidly increasing owing to Hyper Suprime-Cam (HSC) on the Subaru Telescope. The project is called Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs), which discovered 162 new quasars so far, increasing the quasar number density at z ~ 6 by a factor of > 10. Utilizing the SHELLQs quasars along with previously found brighter quasars, we, for the first time, attempt to detect clustering signal of quasars at z ~ 6. We independently evaluate several correlation functions to estimate the bias parameter and DMH mass, and consistently obtain considerably high bias, which is conparable to ~ 6 × 10^12 Msun/h. We find that quasars always inhabit DMHs of mass M_DMH ~ 10^12.5 Msun/h over the cosmic time. The bias parameter is found to be consistent with a model, which assumes the feedback is highly inefficient at z ~ 6. In this talk, we will describe the details of our analysis, comparisons with low redshift results, and implications for the feedback, duty cycle, and host stellar mass.
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