A New Auto-Guiding System for Cquean

Choi, Nahyun; Park, Won-Kee; Lee, Hye-In; Ji, Tae-Geun; Jeon, Yiseul; Im, Myungshin; Pak, Soojong

doi:10.5303/jkas.2015.48.3.177

Cited by 6 publications

(5 citation statements)

References 12 publications

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“…In addition to this, we developed the SED Camera for Quasars in EArly uNiverse (SQUEAN; Kim et al 2016;Choi et al 2015), as an upgraded instrument of the Camera for Quasars in EArly uNiverse (CQUEAN; Park et al 2012;Kim et al 2011;Lim et al 2013), on the 2.1 m Otto Struve Telescope of McDonald Observatory. This new instrument works with 20 filters consisting of broad-band filters (e.g., griz) and 50 nm medium bandwidth filters of which the central wavelengths range 675 to 1025 nm (m675-m1025 1 ).…”

Section: Introductionmentioning

confidence: 99%

The Infrared Medium-deep Survey. VI. Discovery of Faint Quasars at z ∼ 5 with a Medium-band-based Approach

Kim

Jeon

et al. 2019

ApJ

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The faint quasars with M 1450 > −24 mag are known to hold the key to the determination of the ultraviolet emissivity for the cosmic re-ionization. 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 deg 2 areas in J-band to the depths of J AB ∼ 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 < M 1450 < −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 quasars selection. We derived photometric redshifts from the medium-band data, and find that they have high accuracies of |∆z|/(1 + z) = 0.016. The mediumband-based approach allows us to rule out many of the interlopers that contaminate 20 % of the broad-band-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 re-ionization history. dreds of them being at high redshift of z 5 (Fan et al.1 The medium-band filters are named as m (initial of the medium-band) + the central wavelength of the filter in nm.

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Section: Introductionmentioning

confidence: 99%

The Infrared Medium-deep Survey. VI. Discovery of Faint Quasars at z ∼ 5 with a Medium-band-based Approach

Kim

Jeon

et al. 2019

ApJ

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“…As an attempt to improve the selection of high redshift quasars, we devised a set of 9 medium-band filters to better trace SEDs of various sources and modified CQUEAN to allow the usage as many as 20 filters. We now call this modified CQUEAN the SED camera for QUasars in EArly uNiverse (SQUEAN; Kim et al in preparation;Choi et al 2015). Like CQUEAN, SQUEAN operates on the 2.1 m Otto Struve Telescope at the McDonald Observatory.…”

Section: Introductionmentioning

confidence: 99%

THE INFRARED MEDIUM-DEEP SURVEY. V. A NEW SELECTION STRATEGY FOR QUASARS AT z > 5 BASED ON MEDIUM-BAND OBSERVATIONS WITH SQUEAN

Jeon¹,

Im²,

Pak³

et al. 2016

Journal of The Korean Astronomical Society

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We present our first results of the survey for high redshift quasars at 5 z 5.7. The search for quasars in this redshift range has been known to be challenging due to limitations of filter sets used in previous studies. We conducted a quasar survey for two specific redshift ranges, 4.60 ≤ z ≤ 5.40 and 5.50 ≤ z ≤ 6.05, using multi-wavelength data that include observations using custom-designed filters, is and iz. Using these filters and a new selection technique, we were able to reduce the fraction of interlopers. Through optical spectroscopy, we confirmed seven quasars at 4.7 ≤ z ≤ 5.4 with −27.4 < M 1450 < −26.4 which were discovered independently by another group recently. We estimated black hole masses and Eddington ratios of four of these quasars from optical and near-infrared spectra, and found that these quasars are undergoing nearly Eddington-limited accretion which is consistent with the rapid growth of supermassive black holes in luminous quasars at z ∼ 5.

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“…To narrow down the number of plausible z ∼ 5 quasar candidates, follow-up observations of these broadbandselected candidates were carried out in medium bands with the SED Camera for Quasars in Early Universe (SQUEAN; Choi et al 2015;Kim et al 2016) on the Otto Struve 2.1 m Telescope at McDonald Observatory. At z ∼ 5, the Lyα λ1216 line is located at ∼ 7300 Å, so we have obtained m675, m725, and m775 images, where the filter names are chosen by combining "m" for medium-band and the number of the central wavelength of the filter in nanometers.…”

Section: Squean Follow-up Imaging In Medium Bandsmentioning

confidence: 99%

The Infrared Medium-deep Survey. VIII. Quasar Luminosity Function at $z\sim5$

Kim,

Im,

Jeon

et al. 2020

Preprint

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Faint z ∼ 5 quasars with M 1450 ∼ −23 mag are known to be the potentially important contributors to the ultraviolet ionizing background in the post-reionization era. However, their number density has not been well determined, making it difficult to assess their role in the early ionization of the intergalactic medium (IGM). In this work, we present the updated results of our z ∼ 5 quasar survey using the Infrared Medium-deep Survey (IMS), a near-infrared imaging survey covering an area of 85 deg 2 . From our spectroscopic observations with the Gemini Multi-Object Spectrograph (GMOS) on the Gemini-South 8 m Telescope, we discovered eight new quasars at z ∼ 5 with −26.1 ≤ M 1450 ≤ −23.3. Combining our IMS faint quasars (M 1450 > −27 mag) with the brighter Sloan Digital Sky Survey (SDSS) quasars (M 1450 < −27 mag), we derive the z ∼ 5 quasar luminosity function (QLF) without any fixed parameters down to the magnitude limit of M 1450 = −23 mag. We find that the faint-end slope of the QLF is very flat (α = −1.2 +1.4 −0.6 ), with a characteristic luminosity of M * 1450 = −25.8 +1.4 −1.1 mag. The number density of z ∼ 5 quasars from the QLF gives an ionizing emissivity at 912 Å of 912 = (3.7-7.1) × 10 23 erg s −1 Hz −1 Mpc −3 and an ionizing photon density of ṅion = (3.0-5.7) × 10 49Mpc −3 s −1 . These results imply that quasars are responsible for only 10-20% (up to 50% even in the extreme case) of the photons required to completely ionize the IGM at z ∼ 5, disfavoring the idea that quasars alone could have ionized the IGM at z ∼ 5.

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A New Auto-Guiding System for Cquean

Cited by 6 publications

References 12 publications

The Infrared Medium-deep Survey. VI. Discovery of Faint Quasars at z ∼ 5 with a Medium-band-based Approach

The Infrared Medium-deep Survey. VI. Discovery of Faint Quasars at z ∼ 5 with a Medium-band-based Approach

THE INFRARED MEDIUM-DEEP SURVEY. V. A NEW SELECTION STRATEGY FOR QUASARS AT z > 5 BASED ON MEDIUM-BAND OBSERVATIONS WITH SQUEAN

The Infrared Medium-deep Survey. VIII. Quasar Luminosity Function at $z\sim5$

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