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Full-Text Articles in Physical Sciences and Mathematics
Microjansky Source Counts And Spectral Indices At 8.44 Ghz, Rogier A. Windhorst, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal
Microjansky Source Counts And Spectral Indices At 8.44 Ghz, Rogier A. Windhorst, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal
Astronomy: Faculty Publications
We used the VLA to make deep images of two 7′ × 7′ fields at 8.44 GHz with 10″ resolution. With an rms noise of 3.2 and 5.1 μJy, respectively, in the two fields, we compiled a catalog of 82 sources. From the complete sample of 20 sources with S ≥ 14.5 μJy, the differential 8.44 GHz source count is dN(S)/ dS = (-4.6 ± 0.7) × S-2.3 ± 0.2 Jy-1 sr-1 in the range 14.5-1000 mJy. Analysis of statistical image fluctuations from weak sources (Fomalont et al. 1993) suggests that this slope remains unchanged at γ = 2.3 ± …
Limits To Cosmic Background Radiation Fluctuations At 8.44 Ghz Between Angular Scales 10″ And 200″, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal, Rogier A. Windhorst
Limits To Cosmic Background Radiation Fluctuations At 8.44 Ghz Between Angular Scales 10″ And 200″, Edward B. Fomalont, R. Bruce Partridge, James D. Lowenthal, Rogier A. Windhorst
Astronomy: Faculty Publications
We have used the VLA at 8.44 GHz to measure fluctuations in the cosmic background radiation (CBR) from two deep images, each 7′ x 7′ in size. No fluctuations between the angular scales 10″ and 200″ were detected. The most accurate limit (95% confidence) is ΔT/TCBR < 1.9 x 10-5 for 80″ resolution. For random Gaussian fluctuations with coherence angle θc, the limits are ΔT/TCBR < 30 x 10-5 for 22″ < θc < 60″. Outside this range the limits increase to ΔT/TCBR < 5 x 10-5 at θc = 12″ or 100″ and ΔT/TCBR < 10 x 10-5 at θc = 5″ or 120″. Similar limits have been obtained for the circularly and linearly polarized components of the CBR fluctuations. These limits were derived from the residual fluctuations in the images after (1) removing brighter foreground sources (> 14.5 μJy) which covered about 10% of each image; (2) estimating fluctuations of weaker sources by extrapolating the count of dN/dS = 4.6S-2.3 Jy-1 sr-1 to 4 μJy; and (3) determining fluctuations from receiver noise and instrumental errors by comparing the image variances from two independent halves of the data set. All analysis was …