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The Luminosity Function for L > L* Galaxies at z > 3
Bershady, Matthew A.; Majewski, Steven R.; Koo, David C. +2 more
Through the use of multiband (U,BJ,RF,IN) photometry we have isolated high-redshift (3.0<z<3.5) galaxy candidates in surveys of 1.27 deg2 to RF=21.25 and 0.02 deg2 to RF=23.5. Our pool of candidates constrains the nature of the 3.0<z<3.5 luminosity function ov…
The Long-Term Periodic Oscillation of the NGC 4151 Nucleus
Lyuty, V. M.; Kotov, V. A.; Haneychuk, V. I. +3 more
The hypothesis that the luminosity of the nucleus of the Seyfert 1 galaxy NGC 4151 varies with a period of P0 ~ 160.0101 minutes is revised. In 1987-1994 a series of photometric observations of the NGC 4151 has been carried out in the U and V filters at several instruments. In the total sample of 27 nights, the U data of 15 nights showe…
Evidence Against Broad Absorption Lines in the X-Ray-bright Quasar PG 1416-129
Green, Paul J.; Mathur, Smita; Schartel, Norbert +1 more
Recent results from the ROSAT All-Sky Survey and from deep ROSAT pointings reveal that broad absorption line quasars (BALQSOs) are weak in the soft X-ray bandpass (αox > 1.8) in comparison to QSOs with normal OUV spectra (αox = 1.4). One glaring exception appeared to be the nearby BALQSO PG 1416-129, which is a bright ROSA…
Probing Galactic Center Black Hole Candidates with Far-Infrared Spectroscopy
Hollenbach, David J.; Colgan, Sean W. J.; Maloney, Philip R.
The narrow positron annihilation line source in the Galactic center has been identified with the X-ray source 1E 1740.7-2942, which is coincident in projection with a Galactic center molecular cloud and exhibits synchrotron jets in the radio spectrum. It has been suggested that the source is powered by Bondi-Hoyle accretion from the cloud onto a c…
Effects of High Ion Temperatures on Spectral Line Diagnostics in the Source Region of the High-speed Solar Wind
Esser, R.; Brickhouse, N. S.
Theoretical work on solar wind acceleration has suggested that the proton and electron temperatures at the base of the solar coronal hole region are not thermally equilibrated but that instead the proton temperature may exceed the electron temperature significantly. Recently, Kohl, Strachan, & Gardner have measured both broad and narrow compon…
Ly alpha Constraints on the Nature of the X-Ray--absorbing Medium in Cooling Flow Clusters
Laor, Ari
X-ray spectra of a significant fraction of cooling flow (CF) clusters of galaxies indicate the presence of large columns of ``cold'' absorbing material. The physical nature of the absorbing medium remains a mystery. Searches for H I in this medium using the 21 cm hyperfine structure line yielded null results in most cases. The Lyα absorption cross…
Emission Lines from Companion Galaxies of QSOs
Gnedin, Oleg Y.
Anticipating new spectroscopic studies of quasar companions, we calculate expected emission-line spectra for the companion galaxies. Under the assumption of isotropic photoionizing radiation, we predict equivalent widths for Hα, Hβ, [O III] λ5007, [O II] λ3727, [Ne III] λ3869, and Mg II λ2798 lines. We consider six quasars, two of which (PKS 2135-…
[O V] in the Ultraviolet Spectra of Gaseous Nebulae
Feibelman, W. A.; Keenan, F. P.; Hyung, S. +5 more
Theoretical O V electron-density-sensitive emission line ratios for R = I(2s2 1S0 - 2s2p 3P2)/I(2s2 1S0 - 2s2p 3P1) are presented. Inspection of Goddard High Resolution Spectrograph Hubble Space Telescope spectra of RR Tel reveals the pres…
Neutral Hydrogen Gunn-Peterson Absorption from an Overdensity in the Diffuse Intergalactic Medium at Redshift 0.8?
Turnshek, David A.; Khersonsky, Valery K.; Strub, Sheflynn M.
The results of a search for diffuse neutral hydrogen ``Gunn-Peterson'' absorption, including possible absorption from any overdensity in the diffuse intergalactic medium, at low to moderate redshifts (z < 1.2) are discussed. The relatively low incidence of Lyα forest lines at these redshifts makes this work more straightforward than would be th…
Estimate of the Energy Flux from Time-Distance Analysis
Ryutova, M.
In this Letter we show that time-distance measurements in helioseismology can be used to estimate the energy flux on the solar surface. Nonreciprocity of travel time along the ray path and different parity properties of sound speed, flow velocity, and magnetic field allow one to obtain information on large-scale distribution of plasma flows and ma…