Astrophysical Polarimetry of Cosmological Sources

Kostelecky and Mewes have recently shown that sensitive constraints can be placed on some aspects of Lorentz symmetry violation using certain astronomical data on high-redshift sources. Here, I introduce that data in its astronomical context, making it clear that these data are robust and accurate for their purpose. In particular, I explain that spatially extended scattered light from obscured quasars leads to a centrosymmetric scattering polarization, with polarization position angle independent of wavelength. Evidentally, these relationships aren't spoiled by propagation effects as the photons cross the universe.Comment: 7 pages, 4 figures, Second Meeting on CPT and Lorentz Symmetry, Bloomington, IN (Aug. 2001

A First Close Look at the Balmer-edge Behavior of the Quasar Big Blue Bump

We have found for the first time a Balmer edge feature in the Big Blue Bump emission of a quasar. The feature is seen in the polarized flux spectrum of the quasar, where all the emissions from outside the nucleus are scraped off and removed. The existence of the Balmer-edge absorption feature directly indicates that the Big Blue Bump is indeed thermal and optically-thick.Comment: 2 pages, 2 figures. To be published in conference proceedings "Active Galactic Nuclei: from Central Engine to Host Galaxy

Extremely Luminous Water Vapor Emission from a Type 2 Quasar at Redshift z = 0.66

A search for water masers in 47 Sloan Digital Sky Survey Type 2 quasars using the Green Bank Telescope has yielded a detection at a redshift of z = 0.660. This maser is more than an order of magnitude higher in redshift than any previously known and, with a total isotropic luminosity of 23,000 L_sun, also the most powerful. The presence and detectability of water masers in quasars at z ~ 0.3-0.8 may provide a better understanding of quasar molecular tori and disks, as well as fundamental quasar and galaxy properties such as black hole masses. Water masers at cosmologically interesting distances may also eventually provide, via direct distance determinations, a new cosmological observable for testing the reality and properties of dark energy, currently inferred primarily through Type 1a supernova measurements.Comment: 8 pages including 1 figure; accepted for publication in ApJ Letter