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Improvement of Moderate Redshift Quasar Surveys Utilizing Infrared and Optical Data

Improvement of Moderate Redshift Quasar Surveys Utilizing Infrared and Optical Data. Ashley Stewart, Shelly Bursick, Julia Kennefick University of Arkansas. What is a Quasar?. Bright centers of active galaxies. Lie at great distances, billions of light years away.

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Improvement of Moderate Redshift Quasar Surveys Utilizing Infrared and Optical Data

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  1. Improvement of Moderate Redshift Quasar Surveys Utilizing Infrared and Optical Data Ashley Stewart, Shelly Bursick, Julia Kennefick University of Arkansas

  2. What is a Quasar? • Bright centers of active galaxies. • Lie at great distances, billions of light years away. • Have large observed redshifts. • Important to the study of the evolution of galaxies.

  3. Detection Methods • First quasars were discovered in the 1960’s using radio technology. • The most successful method of detection is using optical telescopes. • Optical surveys account for most known quasars but are incomplete.

  4. Challenges with Optical Surveys • Quasar activity is found to peak between redshifts 2<z<3. • Optical surveys are incomplete at these redshifts. • Incompleteness due to quasar’s similarity in color to stars at redshifts 2<z<3.

  5. Advantage of Infrared Data Addition • To improve the selection of quasars of redshift 2<z<3, the addition of infrared data could be useful. Z=4 Z=3 Z=3 Z=2 Z=2 Z=4

  6. Our Project • Cross match infrared data from the 2- Micron All Sky Survey (2MASS) with the optical data from the Sloan Digital Sky Survey (SDSS). • Computed colors. • Graphed the data in color-color space with a stellar locus and modeled quasar data.

  7. Data Analysis • Selected candidates that diverged from the stellar locus and that were within the same color space as synthetic quasar data. • Determined if these candidates had undergone spectral analysis by checking the Sloan Digital Sky Survey (SDSS). • Those without spectra will be considered for follow up spectroscopy.

  8. Results

  9. Conclusion • Have been approved for time at the 2.1m at KPNO. • Will be taking spectroscopy of 200 candidates. • Follow up spectroscopy will determine if addition of infrared imaging to optical surveys improves quasar selection at 2<z<3. • Thereby, improving the accuracy of determinations of quasar space densities.

  10. Acknowledgements • The Arkansas Center for Space and Planetary Sciences. • The NSF and NVO for funding the project. • The Sloan Digital Sky Survey and the 2 Micron All Sky Survey for use of their data.

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