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High frequency peakers. I. The bright sample
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AA manuscript no.
(will be inserted by hand later)
Your thesaurus codes are:
03 11.01.2 13.18.1 11.17.3
ASTRONOMY
AND
ASTROPHYSICS
High Frequency Peakers: I. The Bright Sample
D. Dallacasa1,2, C. Stanghellini3, M. Centonza1,2, and R. Fanti4,2
1 Dipartimento di Astronomia, Via Ranzani 1, I-40127 Bologna, Italy
2 Istituto di Radioastronomia - CNR, Via Gobetti 101, I-40129 Bologna, Italy.
3 Istituto di Radioastronomia - C. P. 169, I-96017 Noto (SR), Italy
4 Dipartimento di Fisica, Via Irnerio n. 46, I-40126 Bologna, Italy.
Received 11 July 2000; accepted 9 October 2000
Abstract. Here we present a sample of sources with con-
vex radio spectra peaking at frequencies above a few
GHz. We call these radio sources High Frequency Peakers
(HFPs). This sample extends to higher turnover frequen-
cies than the samples of Compact Steep Spectrum (CSS)
and GHz Peaked Spectrum (GPS) radio sources. HFPs
are rare due to the strong bias against them caused by
their turnover occurring at frequencies about one order of
magnitude higher than in CSS-GPS samples.
The sample has been selected by a comparison between
the Green Bank survey (87GB) at 4.9 GHz and the NRAO
VLA Sky Survey (NVSS) at 1.4 GHz. Then the candidates
have been observed with the VLA at 1.365, 1.665, 4.535,
4.985, 8.085, 8.485, 14.96 and 22.46 GHz in order to de-
rive a simultaneous radio spectrum, and remove variable
sources from the sample. The final list of genuine HFP
sources consists of 55 objects with flux density exceeding
300 mJy at 4.9 GHz at the time of the 87GB observa-
tion. Optical identifications are available for 29 of them;
24 are high redshift quasars, 3 are galaxies (one of them
has indeed broad lines in the optical spectrum) and 2 are
BL Lac objects. The remaining sources are mostly empty
fields (17) on the digitised POSS or have uncertain classi-
fication (9).
Key words: Galaxies: active – Radio Continuum: Galax-
ies – Quasars: Genera
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