%0 Generic %1 kim2015discovery %A Kim, Yongjung %A Im, Myungshin %A Jeon, Yiseul %A Kim, Minjin %A Choi, Changsu %A Hong, Jueun %A Hyun, Minhee %A Jun, Hyunsung David %A Karouzos, Marios %A Kim, Dohyeong %A Kim, Duho %A Kim, Jae-Woo %A Kim, Ji Hoon %A Lee, Seong-Kook %A Pak, Soojong %A Park, Won-Kee %A Taak, Yoon Chan %A Yoon, Yongmin %D 2015 %K faint quasar z6 %R 10.1088/2041-8205/813/2/L35/ %T Discovery of A Faint Quasar at z~6 and Implications for Cosmic Reionization %U http://arxiv.org/abs/1511.01585 %X Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars ($M_1450>-24$ mag) at $z \gtrsim6$, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z~6 in a 12.5 deg$^2$ region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at $\sim8443~\AA$, with emission lines redshifted to $z=5.944 0.002$ and rest-frame ultraviolet continuum magnitude $M_1450=-23.59\pm0.10$ AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z~6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars . This suggests that the number of $M_1450\sim-23$ mag quasars at z~6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.

@misc{kim2015discovery, abstract = {Recent studies suggest that faint active galactic nuclei may be responsible for the reionization of the universe. Confirmation of this scenario requires spectroscopic identification of faint quasars ($M_{1450}>-24$ mag) at $z \gtrsim6$, but only a very small number of such quasars have been spectroscopically identified so far. Here, we report the discovery of a faint quasar IMS J220417.92+011144.8 at z~6 in a 12.5 deg$^{2}$ region of the SA22 field of the Infrared Medium-deep Survey (IMS). The spectrum of the quasar shows a sharp break at $\sim8443~\rm{\AA}$, with emission lines redshifted to $z=5.944 \pm 0.002$ and rest-frame ultraviolet continuum magnitude $M_{1450}=-23.59\pm0.10$ AB mag. The discovery of IMS J220417.92+011144.8 is consistent with the expected number of quasars at z~6 estimated from quasar luminosity functions based on previous observations of spectroscopically identified low-luminosity quasars . This suggests that the number of $M_{1450}\sim-23$ mag quasars at z~6 may not be high enough to fully account for the reionization of the universe. In addition, our study demonstrates that faint quasars in the early universe can be identified effectively with a moderately wide and deep near-infrared survey such as the IMS.}, added-at = {2015-11-06T10:02:33.000+0100}, author = {Kim, Yongjung and Im, Myungshin and Jeon, Yiseul and Kim, Minjin and Choi, Changsu and Hong, Jueun and Hyun, Minhee and Jun, Hyunsung David and Karouzos, Marios and Kim, Dohyeong and Kim, Duho and Kim, Jae-Woo and Kim, Ji Hoon and Lee, Seong-Kook and Pak, Soojong and Park, Won-Kee and Taak, Yoon Chan and Yoon, Yongmin}, biburl = {https://www.bibsonomy.org/bibtex/2412ae3998ae4432780b1bb8ecd73cbcd/miki}, description = {[1511.01585] Discovery of A Faint Quasar at z~6 and Implications for Cosmic Reionization}, doi = {10.1088/2041-8205/813/2/L35/}, interhash = {61452f2a5ed4c23fcf6192bf510ab82d}, intrahash = {412ae3998ae4432780b1bb8ecd73cbcd}, keywords = {faint quasar z6}, note = {cite arxiv:1511.01585Comment: 5 pages, 4 figures, 1 table. Published in ApJ Letters}, timestamp = {2015-11-06T10:02:33.000+0100}, title = {Discovery of A Faint Quasar at z~6 and Implications for Cosmic Reionization}, url = {http://arxiv.org/abs/1511.01585}, year = 2015 }