Counts and spectral indices at 8.44GHz

DOI

We used the VLA to make deep images of two 7x7' fields at 8.44 GHz with 10" resolution. With an rms noise of 3.2 and 5.1 {micro}Jy, respectively, in the two fields, we compiled a catalog of 82 sources. The normalized differential 8.44 GHz counts are similar to those at 1.41 and 4.86 GHz. All show a similarly steep submillijansky slope, which is only somewhat flatter than that expected for a nonevolving Euclidean population ({gamma}=2.5). Microjansky radio sources at 4.86 GHz have been identified with faint blue galaxies (18<~V<~28 mag). We argue that their expected median redshift is about 0.5-0.75. Hence, cosmological evolution may be needed to explain the steep slope of the microjansky counts. The 8.44 GHz counts must converge with slope {gamma}<2.0 below S(8.44)~300 nJy, or they would exceed the available field galaxy counts down to V~28 mag, and they must permanently converge below S(8.44)~20 nJy, or their integrated sky brightness would distort the observed thermal cosmic background radiation spectrum at centimeter wavelengths. The estimated 31.5 GHz sky brightness from nanojansky to jansky levels is <36 {micro}K (3{sigma}). Even if weak radio sources cluster on scales of degrees as faint galaxies do, their anisotropic contribution to the COBE DMR experiment (with 7deg FWHM-beam) would not exceed ~1.2{micro}K.

Cone search capability for table J/ApJ/405/498/table1b (Catalog of 8.44 GHz Radio Sources in the Cepheus Field)

Cone search capability for table J/ApJ/405/498/table1a (Catalog of 8.44 GHz Radio Sources in the Linx.2 Field)

Identifier
DOI http://doi.org/10.26093/cds/vizier.14050498
Source https://dc.g-vo.org/rr/q/lp/custom/CDS.VizieR/J/ApJ/405/498
Related Identifier https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/405/498
Related Identifier http://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/405/498
Metadata Access http://dc.g-vo.org/rr/q/pmh/pubreg.xml?verb=GetRecord&metadataPrefix=oai_b2find&identifier=ivo://CDS.VizieR/J/ApJ/405/498
Provenance
Creator WINDHORST R.A.; FOMALONT E.B.; PARTRIDGE R.B.; LOWENTHAL J.D.
Publisher CDS
Publication Year 1997
Rights https://cds.unistra.fr/vizier-org/licences_vizier.html
OpenAccess true
Contact CDS support team <cds-question(at)unistra.fr>
Representation
Resource Type Dataset; AstroObjects
Discipline Astrophysics and Astronomy; Cosmology; Natural Sciences; Physics