An Investigation of the Strong Radio Sources in Centaurus, Fornax, and Puppis

Abstract

SummaryIsophotes of three strong southern radio sources have been prepared from observa· tions at a wavelength of 3·5 m with a 50 min pencil·beam system. The two extragalactic sources Centaurus-A and Fornax-A are found to have extensive coronas very much larger than the size of the associated galaxies. Using optical estimates of distance these two sources are shown to have similar spatial extensions and may be physically similar systems. The third source, Puppis-A, may be the remnants of a galactic supernova of type II.

The Eta Carinae Nebula and Centaurus A Near 1400mc/s. I. Observations

“…There is a strong, broad maximum in the intensity of this component at On the whole, Figure 7 bears a remarkably close resemblance to the 85·5 Mcjs chart published by Sheridan (1958). The position found for the primary maximum is in satisfactory agreement with the results obtained previously at metre wavelengths, as shown in Table 2.…”

“…(b) Centauru8 A We have found that the appearance of Centaurus A (13S4A) at 1400 Mcjs is similar to that previously observed at 85·5 Mc!s by Sheridan (1958). The source consists of two components: one is a point source evidently associated with the peculiar galaxy NGC 5128; the other is a very large extended source with no known optical counterpart.…”

“…Early interferometric observations (Stanley and Slee 1950) indicated that it consists of two components: one, a strong source of small angular size coinciding in position with NGC 5128; the other, a broad, faint extended source surrounding NGC 5128. The extended source has been shown in good detail by recent pencil-beam observations at 19·7 Mc/s (Shain 1958) and at 85·5 Mc/s (Sheridan 1958). It is highly elongated in the north-south direction and covers an area of more than 20 square degrees.…”

Radio Emission from the Vela?Puppis Region

“…A detailed study of the source at 3·5 m 'Wavelength has been made by Sheridan (1958), and the flux density quoted in Table 1, which is the author's estimate, must be regarded as provisional. Values ·of its flux density at several other wavelengths have been reported, but it is now .clear that most of the observations were subject to confusion with the other intense sources nearby.…”

Centaurus A: constraints on the nature of the giant lobe filaments fromXMM-Newtonobservations

“…Since the first radio isophotes of the giant lobes were reported by Sheridan (1958) and Shain (1958), Centaurus A's largescale structure has been extensively studied at radio frequencies, covering a wide range from 118 MHz to 41 GHz (Cooper et al 1965;Haynes et al 1983;Junkes et al 1993;Combi & Romero 1997;Alvarez et al 2000;Israel et al 2008;Feain et al 2009;Hardcastle et al 2009;Feain et al 2011;McKinley et al 2013; O'Sullivan et al 2013; Stefan et al 2013). These studies re-⋆ E-mail: sw@extragalactic.info vealed, for instance, lobe synchrotron ages of order 30 Myr (Hardcastle et al 2009), relatively flat global spectral indices (Hardcastle et al 2009;McKinley et al 2013), the presence of substructure and some constraints on its origin (Feain et al 2011), and an upper limit on the thermal electron content of n e,th < 5 × 10 −5 cm −3 ).…”