2019ApJ...870...86K -
Astrophys. J., 870, 86-86 (2019/January-2)
The Infrared Medium-deep Survey. VI. Discovery of faint quasars at z ∼ 5 with a medium-band-based approach.
KIM Y., IM M., JEON Y., KIM M., PAK S., TAAK Y.C., CHOI C., HONG J., HYUN M., JI T.-G., JUN H.D., KAROUZOS M., KIM D., KIM D., KIM J.-W., KIM J.H., LEE H.-I., LEE S.-K., PARK W.-K., YOON Y., BYEON S., HWANG S., KIM J., KIM S., LIM G., PAEK I., PARK W. and SHIN S.
Abstract (from CDS):
The faint quasars with M1450 > -24 mag are known to hold the key to the determination of the ultraviolet emissivity for the cosmic reionization. But only a few have been identified so far because of the limitations on the survey data. Here we present the first results of the z ∼ 5 faint quasar survey with the Infrared Medium-deep Survey (IMS), which covers ∼100 deg2 areas in J band to the depths of JAB ∼ 23 mag. To improve selection methods, the medium-band follow-up imaging has been carried out using the SED camera for QUasars in Early uNiverse (SQUEAN) on the Otto Struve 2.1 m Telescope. The optical spectra of the candidates were obtained with 8 m class telescopes. We newly discovered 10 quasars with -25 < M1450 < -23 at z ∼ 5, among which three have been missed in a previous survey using the same optical data over the same area, implying the necessity for improvements in high-redshift faint quasar selection. We derived photometric redshifts from the medium-band data and found that they have high accuracies of <| Δz|/(1+z)>=0.016. The medium-band-based approach allows us to rule out many of the interlopers that contaminate >=20% of the broadband-selected quasar candidates. These results suggest that the medium-band-based approach is a powerful way to identify z ∼ 5 quasars and measure their redshifts at high accuracy (1%-2%). It is also a cost-effective way to understand the contribution of quasars to the cosmic reionization history.
Abstract Copyright:
© 2019. The American Astronomical Society. All rights reserved.
Journal keyword(s):
cosmology: observations - galaxies: active - galaxies: high-redshift - quasars: supermassive black holes - surveys
Nomenclature:
Tables 1-6: IMS JHHMMSS+DDMMSS N=49.
Simbad objects:
52
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