Year: 2019
Type: article
Abstract: We present the results of the Extremely Luminous Quasar Survey in the 3 π survey of the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS; PS1). This effort applies the successful quasar selection strategy of the Extremely Luminous Survey in the Sloan Digital Sky Survey footprint (∼12,000 deg 2 ) to a much larger area (∼21,486 deg 2 ). This spectroscopic survey targets the most luminous quasars ( M 1450 ≤ −26.5; m i ≤ 18.5) at intermediate redshifts ( z ≥ 2.8). Candidates are selected based on a near-infrared JKW 2 color cut using WISE AllWISE and 2MASS photometry to mainly reject stellar contaminants. Photometric redshifts ( z reg ) and star−quasar classifications for each candidate are calculated from near-infrared and optical photometry using the supervised machine learning technique random forests. We select 806 quasar candidates at z reg ≥ 2.8 from a parent sample of 74,318 sources. After exclusion of known sources and rejection of candidates with unreliable photometry, we have taken optical identification spectra for 290 of our 334 good PS-ELQS candidates. We report the discovery of 190 new z ≥ 2.8 quasars and an additional 28 quasars at lower redshifts. A total of 44 good PS-ELQS candidates remain unobserved. Including all known quasars at z ≥ 2.8, our quasar selection method has a selection efficiency of at least 77%. At lower declinations, −30 ≤ decl. ≤ 0, we approximately treble the known population of extremely luminous quasars. We provide the PS-ELQS quasar catalog with a total of 592 luminous quasars ( m i ≤ 18.5, z ≥ 2.8). This unique sample will not only be able to provide constraints on the volume density and quasar clustering of extremely luminous quasars, but also offers valuable targets for studies of the intergalactic medium.
Authors: Jan-Torge Schindler, Xiaohui Fan, Yun-Hsin Huang, Minghao Yue, Jinyi Yang, Patrick B. Hall, Lukas Wenzl, Allison Hughes, Katrina C. Litke, Jon M. Rees
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: A NEOWISE SURVEY OF QUASARS IN THE EPOCH OF REIONIZATIONLUMINOUS QUASARS AT HIGH REDSHIFT PROVIDE DIRECT PROBES OF THE EVOLUTION OF SUPERMASSIVE BLACK HOLES (BHS) AND INTERGALACTIC MEDIUM (IGM) AT EARLY COSMIC TIME. MORE THAN 100 QUASARS HAVE NOW BEEN DISCOVERED AT Z>6 WITH THE HIGHEST REDSHIFT AT Z=7.1. DETECTIONS OF SUCH OBJECTS INDICATE THE EXISTENCE OF BILLION SOLAR MASS BHS MERELY A FEW HUNDRED MYRS AFTER THE FIRST STAR FORMATION IN THE UNIVERSE CHALLENGING THE THEORY OF BH GROWTH AND BH-GALAXY COEVOLUTION AT EARLY EPOCH. ABSORPTION SPECTRA OF THE HIGHEST REDSHIFT QUASARS REVEAL COMPLETE GUNN-PETERSON ABSORPTION FROM AN INCREASING NEUTRAL IGM MARKING THE END OF THE REIONIZATION EPOCH AT Z>6. COMBINED WITH OBSERVATIONS OF CMB POLARIZATION AND HIGH-REDSHIFT LY ALPHA GALAXIES CURRENT DATA STRONGLY SUGGEST A PEAK OF REIONIZATION ACTIVITY AND EMERGENCE OF THE EARLIEST GALAXIES AND AGNS AT 7<Z<11 HIGHLIGHTING THE NEED TO EXPAND QUASAR SEARCH TO HIGHER REDSHIFT. HOWEVER FINDING Z>7 QUASARS HAS BEEN CHALLENGING: ONLY ONE QUASAR HAS BEEN DISCOVERED AT Z>7 AND A HANDFUL AT Z>6.5. IN THIS ADAP PROGRAM WE WILL CARRY OUT THE FIRST COMPREHENSIVE SURVEY OF Z>=7 QUASARS USING A WISE-BASED SELECTION ALGORITHM DEEP MID-IR PHOTOMETRY FROM COADDED NEOWISE DATA AND DEEP OPTICAL AND NEAR-IR PHOTOMETRY FROM NEW WIDE-FIELD IMAGING SURVEYS. WE WILL SELECT AND FOLLOW-UP QUASAR CANDIDATES OVER>20 000 DEG^2 OF HIGH GALACTIC LATITUDE SKY AIMING AT FINDING ~10-15 QUASARS AT Z>=7 IN THE NEXT THREE YEARS. THERE ARE TWO MAIN TECHNICAL COMPONENTS OF OUR PROGRAM. (1) WISE-BASED QUASAR SELECTION. WE HAVE DEVELOPED A HIGHLY SUCCESSFUL SELECTION METHOD BY COMBINING WISE AND OPTICAL/NEAR-IR PHOTOMETRY TO SEARCH FOR LUMINOUS QUASARS AT Z = 4.5-6.5 RESULTED IN THE DISCOVERY OF THE FIRST KNOWN SUPERMASSIVE BLACK HOLES WITH 10 BILLION SOLAR MASS BHS IN THE EARLY UNIVERSE. WE WILL EXPAND AND OPTIMIZE THE ALGORITHM FOR THE REDSHIFT RANGE OF 6.5<Z<8. (2) DEEP COADDED NEOWISE PHOTOMETRY. NEOWISE WILL QUADRUPLE THE EXPOSURE TIME IN W1 AND W2 BANDS COMPARED TO THAT OF ALLWISE CATALOG USED BY PREVIOUS QUASAR SEARCH; HOWEVER ONLY SINGLE EXPOSURE CATALOGS ARE AVAILABLE AS STANDARD DATA PRODUCT. WE WILL USE TRACTOR PIPELINE TO CARRY OUT COADDED FORCED PHOTOMETRY OF NEOWISE IMAGES TO GENERATE JOINT PHOTOMETRIC CATALOG OF MID-IR (NEOWISE) NEAR-IR (UHS AND VHS) AND OPTICAL (DECALS MZLS DES PS1) IMAGING. THE NEW CATALOG WILL REACH 0.6-0.8 MAG DEEPER THAN THE CURRENT ALLWISE CATALOG; THIS IS THE KEY TO THE SUCCESS OF OUR PROGRAM. THE CATALOG WILL BE MADE PUBLICLY AVAILABLE TO THE COMMUNITY. OUR PROGRAM WILL ESTABLISH THE FIRST LARGE SAMPLE OF QUASARS AT THE PEAK OF REIONIZATION ERA. THE SAMPLE WILL BE USED TO MEASURE THE DENSITY OF LUMINOUS QUASARS AND THEIR BH MASSES AT Z>=7 AND PLACE CONSTRAINT ON THE EXISTENCE OF Z>8 QUASARS. THESE MEASUREMENTS WILL TEST WHETHER SUPER-EDDINGTON ACCRETION OR DIRECT FORMATION OF INTERMEDIATE-MASS BHS ARE NEEDED FOR EARLY BH GROWTH. CURRENT QUASAR OBSERVATIONS INDICATE THAT NEUTRAL FRACTION OF THE IGM INCREASED FROM 10^-3 AT Z<6 TO AS HIGH AS 10% AT Z~7. WE WILL EXTEND THESE MEASUREMENTS TO LARGE Z>=7 QUASAR SAMPLE DEFINITIVELY MEASURE THE IGM NEUTRAL FRACTION AT Z~7-8 AND PROBE WHETHER THE REIONIZATION PROCESS RESEMBLES A PHASE TRANSITION OF THE IGM OR FOLLOWS A MORE GRADUAL PATTERN IN THIS CRURAL COSMIC EPOCH. THIS ADAP PROGRAM IS PRIMARILY BASED ON NEW REDUCTION AND ANALYSIS OF ARCHIVAL DATA FROM NASA'S WISE MISSION. STUDIES OF THE FORMATION OF THE EARLIEST GALAXIES AND BHS THE END OF COSMIC DARK AGES AND THE EPOCH OF REIONIZATION IS AMONG THE KEY SCIENCE GOALS OF NASA'S COSMIC ORIGIN PROGRAM AND ONE OF THE HIGHEST PRIORITIES OF THE NASA ASTROPHYSICS ROADMAP AND ASTRO20/20 DECADAL SURVEY. THE NEW QUASARS DISCOVERED IN OUR SURVEY WILL BE PRIME TARGETS FOR DETAILED JWST FOLLOW-UP OBSERVATIONS TO STUDY REIONIZATION HISTORY AND PROVIDE VALUABLE INSIGHT INTO THE DESIGN OF HIGH-REDSIFT QUASAR AND GALAXY SURVEYS USING WFI, G6651774696
OpenAlex ID: W2943861187