J. Scott Bechtold

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1 Observations here were obtained with the Multiple Mirror Telescope, a joint facility of the University of Arizona and the Smithsonian Institution. – 2 – ABSTRACT We present detections of absorption from the ground state and excited states of C I in the z = 1.9731 damped Lyα system of the QSO 0013−004. The excitation temperature between the J = 0 and J = 1(More)
This paper presents an empirical study comparing the effectiveness of four different versions of an on-line database tutorial, each of which calls upon the student to perform a different kind of inference. The general-to-specific version presents instructions in the form of general rules, from which the students expected to infer how to apply the rule in(More)
We analyze a sample of optical light curves for 100 quasars, 70 of which have black hole mass estimates. Our sample is the largest and broadest used yet for modeling quasar variability. The sources in our sample have z < 2.8, 10 42 λL λ (5100Å) 10 46 , and 10 6 M BH /M ⊙ 10 10. We model the light curves as a continuous time stochastic process, providing a(More)
We report the Chandra discovery of an X-ray cluster at redshift z = 1.063 associated with the Compact Steep Spectrum radio loud quasar 3C 186 (Q0740+380). Diffuse X-ray emission is detected out to ∼ 120 kpc from the quasar and contains 741±40 net counts. The X-ray spectrum of the extended emission shows strong Fe-line emission (EW=412eV) at the quasar(More)
We have discovered an X-ray jet with Chandra imaging of the z=1.187 radio-loud quasar PKS 1127-145. In this paper we present the Chandra X-ray data, follow-up VLA observations, and optical imaging using the HST WFPC2. The X-ray jet contains 273±5 net counts in 27 ksec and extends ∼ 30 ′′ from the quasar core, corresponding to a minimum projected linear size(More)
Moderate resolution data for 40 QSOs at z ≈ 2 were combined with spectra of comparable resolution of 59 QSOs with redshifts greater than 1.7 found in the literature to form a large, homogeneous sample of moderate resolution (∼1Å) QSO spectra. These spectra were presented and the statistics of the Lyman α forest were discussed in Paper I. In this analysis,(More)
We have made a ∼ 30 ksec Chandra observation of the redshift z=0.63 GPS quasar B2 0738+313. We detected X-ray emission from the core and have discovered a 200 kpc (projected on the sky) X-ray jet. The X-ray jet is narrow and curves, following the extended radio structure to the south of the quasar, and ending with a hot spot at the southernmost part of the(More)
In this work we use a sample of 318 radio-quiet quasars (RQQ) to investigate the dependence of the ratio of optical/UV flux to X-ray flux, α ox , and the X-ray photon index, Γ X , on black hole mass, UV luminosity relative to Eddington, and X-ray luminosity relative to Eddington. Our sample is drawn from the literature, with X-ray data from ROSAT and(More)
The complex X-ray morphology of the 300 kpc long X-ray jet in PKS 1127-145 (z=1.18 quasar) is clearly discerned in a ∼100 ksec Chandra observation. The jet X-ray surface brightness gradually decreases by an order of magnitude going out from the core. The X-ray spectrum of the inner jet is relatively flat with α X = 0.66 + − 0.15 and steep in the outer jet(More)