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Physics & Astronomy - Astronomy Seminar - Dr. John Timlin, Drexel University

Title: "The Clustering of High-Redshift (2.9 ≤ z ≤ 5.4) Quasars in SDSS Stripe 82"

Tuesday, July 25, 2017
3:00pm – 4:00pm
Wilder 202
Intended Audience(s): Public
Categories: Lectures & Seminars
Abstract:  We present a measurement of the two-point autocorrelation function of 8838 photometrically-selected, high-z quasars over ∼ 120 deg2 . Selection is performed using three machine learning algorithms in six dimensional, optical/mid-infrared color space. Optical data from the Sloan Digitial Sky Survey Stripe 82 is combined with overlapping deep mid-infrared data from the Spitzer IRAC Equatorial Survey and the Spitzer -HETDEX Large-area survey. Our selection is trained on the colors of known high-z quasars from the quasar catalog of Richards et al. (2015). The selected quasar sample spans a redshift range of 2.9 ≤ z ≤ 5.4 and is generally fainter than i = 20.2; a regime which, until now, has lacked sufficient number density to perform measurements of the autocorrelation function of photometrically-classified quasars. We compute the angular correlation function of these data, fitting a single power-law with an index of δ = 1.10 ± 0.018 and amplitude of θ_0 = 0.29 ± 0.012. We estimate the linear bias by fitting a dark matter model to the angular correlation function. At the average redshift of our survey (<z> = 3.48) the bias is b = 5.26 ± 0.17. We split the data into two redshift bins to measure the change of bias as a function of cosmic time; the bias is increasing with increasing redshift, where, at lower-z (<z> = 3.14), we obtain a bias of b = 3.53 ± 0.29 and at higher-z (<z> = 3.80), b = 5.14 ± 0.49; values in agreement with recent studies. Finally, we use these results to constrain models of quasar feedback at high redshift.
 
For more information, contact:
Tressena Manning
tressena.a.manning@dartmouth.edu
603-646-2854
Permanent URL to this event: https://physics.dartmouth.edu/events/event?event=46377

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