From Gemini: “Placing High-Redshift Quasars in Perspective: a Gemini Near-Infrared Spectroscopic Survey”


Gemini Observatory
Gemini Observatory

December 12, 2017
Principal Investigator: Ohad Shemmer, University of North Texas

At sufficiently high redshifts, several prominent quasar emission features (white solid lines) are no longer detectable in the optical spectral range, represented here by the SDSS band that extends between approximately 0.4 micron and 1.0 micron (solid black line).

SDSS Telescope at Apache Point Observatory, near Sunspot NM, USA, Altitude 2,788 meters (9,147 ft)

For the broad Hbeta and narrow [O III] lines, that are rich in diagnostic power, this occurs above redshift 1, including the era of fast quasar growth. Our GNIRS spectroscopic survey will more than triple the observed spectral band, allowing us to observe these and other emission lines in a uniform sample of 416 SDSS quasars at redshifts between 1.5 (dashed line) and 3.5. The available SDSS spectra of these sources, which cover at least the rest-frame ultraviolet C IV emission line, will enable us to establish connections between optical and ultraviolet indicators of fundamental quasar properties while more than doubling the statistics at such high redshifts.

Program Summary:

Our current understanding of supermassive black hole (SMBH) growth in the distant universe is compromised by the lack of key diagnostic rest-frame optical emission lines in quasar spectra. As a consequence, our view of how SMBHs and their host galaxies mutually coevolve during the peak of quasar activity is biased and incomplete. We will therefore obtain high-quality GNIRS spectroscopic observations, in the 1.0-2.5 micron band, for a uniform sample of 416 Sloan Digital Sky Survey (SDSS) quasars at redshifts between 1.5 and 3.5. This project will more than double the existing inventory of near-infrared spectra of luminous quasars at these redshifts. We will determine the most accurate and precise quasar black hole masses, accretion rates, and redshifts, and use the results to derive improved prescriptions for UV-based proxies for these parameters. We will make our data immediately available to the public, provide reduced spectra via a dedicated website, and produce a catalog of measurements and fundamental quasar properties. The improved redshifts will establish velocities of quasar outflows that interact with the host galaxies, as well as tighten measurements of small-scale quasar clustering. Furthermore, our measurements will facilitate a more complete understanding of how the rest-frame UV-optical spectral properties depend on redshift and luminosity, and test whether the physical properties of the quasar central engine evolve over cosmic time. The next generation of cosmological surveys will generate millions of optical quasar spectra, the analysis of which will greatly benefit from the prescriptions developed in this investigation, an invaluable Gemini legacy.


Michael Brotherton, University of Wyoming, USA
Ileana Andruchow, Universidad Nacional de La Plata, Argentina
Todd Boroson, Las Cumbres Observatory, USA
Niel Brandt, Pennsylvania State University, USA
Sergio Cellone, Universidad Nacional de La Plata, Argentina
Gabriel Ferrero, Universidad Nacional de La Plata, Argentina
Sarah Gallagher, University of Western Ontario, Canada
Richard Green, University of Arizona, USA
Joseph Hennawi, University of California Santa Barbara, USA
Paulina Lira, Universidad de Chile, Chile
Adam Myers, University of Wyoming, USA
Richard Plotkin, ICRAR-Curtin, Australia
Gordon Richards, Drexel University, USA
Jessie Runnoe, University of Michigan, USA
Donald Schneider, Pennsylvania State University, USA
Yue Shen, University of Illinois at Urbana-Champaign, USA
Michael Strauss, Princeton University, USA
Chris Willott, NRC Herzberg, Canada
Beverley Wills, University of Texas at Austin, USA

See the full article here .

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Gemini/North telescope at Maunakea, Hawaii, USA,4,207 m (13,802 ft) above sea level

Gemini South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet


Gemini’s mission is to advance our knowledge of the Universe by providing the international Gemini Community with forefront access to the entire sky.

The Gemini Observatory is an international collaboration with two identical 8-meter telescopes. The Frederick C. Gillett Gemini Telescope is located on Mauna Kea, Hawai’i (Gemini North) and the other telescope on Cerro Pachón in central Chile (Gemini South); together the twin telescopes provide full coverage over both hemispheres of the sky. The telescopes incorporate technologies that allow large, relatively thin mirrors, under active control, to collect and focus both visible and infrared radiation from space.

The Gemini Observatory provides the astronomical communities in six partner countries with state-of-the-art astronomical facilities that allocate observing time in proportion to each country’s contribution. In addition to financial support, each country also contributes significant scientific and technical resources. The national research agencies that form the Gemini partnership include: the US National Science Foundation (NSF), the Canadian National Research Council (NRC), the Chilean Comisión Nacional de Investigación Cientifica y Tecnológica (CONICYT), the Australian Research Council (ARC), the Argentinean Ministerio de Ciencia, Tecnología e Innovación Productiva, and the Brazilian Ministério da Ciência, Tecnologia e Inovação. The observatory is managed by the Association of Universities for Research in Astronomy, Inc. (AURA) under a cooperative agreement with the NSF. The NSF also serves as the executive agency for the international partnership.