This is the final version of AR proposal for QSO LF upper limits, using CANDELS data. 821003213 Assigned ID: 4 ----- Attempting Submission 1 (Mon Mar 18 21:08:01 GMT 2019) ----- HST Phase I Proposal 4 (QSO_AR.apt) successfully submitted. Receipt: # 4-1 ----- Attempting Submission 2 (Wed Apr 03 15:10:46 GMT 2019) ----- HST Phase I Proposal 4 (QSO_AR.apt) successfully submitted. Receipt: # 4-2 ----- Attempting Submission 3 (Fri Apr 05 18:13:39 GMT 2019) ----- The formation of supermassive black holes (SMBHs) has been a long-standing subject of astronomy. Hundreds of QSOs have been discovered up to z~7, and the highest redshift one has a black hole mass of almost 10^9 Msun at z=7.54. The formation mechanism of such high-z SMBHs, however, is still under active debate and further observational constrains at higher redshift are required. One of few key approaches is to study the shape of luminosity functions (LFs) as a function of cosmic time - the redshift evolution of the shape can be attributed to different modes of the QSO activity. In this archival proposal, we aim to constrain for the first time the QSO LF at z~8, by using HST legacy data in 5 CANDELS fields. In a previous work with a similar data set of HST, we found that QSOs at this redshift can be effectively selected in a similar manner for high-z galaxies but by selecting point-like sources, with a very low contamination fraction of low-z interlopers and Galactic brown dwarfs. By applying this to publicly available CANDELS data, we will be able to constrain the number density of QSOs down to <10^-5Mpc^-3 at Muv~-24 to -18, a dramatic improvement from current models that span six orders of magnitude. The survey volume is sufficient to distinguish different shapes of the LF (Schechter vs. double power-law). The inferred number density will reveal the contribution to cosmic reionization by low-luminosity QSOs. Identified candidates will be ideal follow-up targets with ground-based spectrographs and future JWST to investigate the origin of SMBHs and the host properties of the highest redshift QSOs. The PI (Morishita) is a postdoc scholar and has been involved in HST observing programs, BoRG, for more than 2 years. He has reduced data from Cycle 22 program (87fields, each of which has 5 different HST filter images) and published the data and paper. One relared paper is in preparation. One related observing program (15702) was approved in HST Cycle26 program. He will be responsible for the data reduction and publication of this archival program. One of the CoIs (Hoag) is a postdoc scholar and working on reducing ongoing Cycle25 BoRG data. One paper is in preparation. 4 CoIs (Stiavelli,Trenti,Treu,Mason) are the collaborators of multiple BoRG programs (Cycles 17, 22, and 25), and have significant experience with observations, data reduction, and publications. 1 CoI (Ferguson) is the CoI of CANDELS, and will contribute to analyzing data and catalog from the survey, and interpreting the results. 1 CoI (Norman) is a theorist studying galaxies and AGNs, and will contribute to interpreting the results. All members of this programs are experienced investigators in related fields of the early universe and evolution of galaxies/QSOs/super massive black holes, with 50> related observations and publications in the past. Massive Black Holes And Their Host Galaxies 0 Regular false false false false false SUPPORTED