MeerKAT

Abstract:

In 1994 June-July we obtained nearly concurrent measurements of Cyg X-3 in hard X-rays and the infrared, using the OSSE instrument on GRO and the UKIRT. OSSE made a high significance measurement of the hard X-ray (> 50 keV) orbital light curve. Five days after the end of the OSSE observations we obtained a good IR /f-band light curve from data covering one orbit of Cyg X-3. Measurements of the light curve phase and shape probe the geometry of the system and the physics of radiation production and scattering. We determined for the first time that the light curve phases are consistent at these two different wavelengths. The light curve shapes were both marginally inconsistent (at about the 0.2% level) with the canonical soft X-ray shape measured by EXOSAT in 1983-1985. Underlying variations in DC IR flux and flaring during the observation make it difficult to draw unambiguous conclusions; more observations, with better IR coverage, are needed.

Abstract:

We present a new deep K-band infrared finder chart for the Cygnus X-3 field, revealing the presence of at least ten previously undetected infrared objects within a few arc seconds of the source. Although these newly-discovered objects have in all likelihood not affected previous infrared spectroscopy or photometry of Cyg X-3, knowledge of their locations is an important consideration for future deep infrared spectroscopy of the source.

Abstract:

(Abridged)One of the fundamental challenges for astrophysics in the 21st century is finding a way to untangle the physical processes that govern galaxy formation and evolution. Given the importance and scope of this problem, the multi-wavelength astronomical community has used the past decade to build up a wealth of information over specific extragalactic deep fields to address key questions in galaxy formation and evolution. These fields generally cover at least 10square degrees to facilitate the investigation of the rarest, typically most massive, galaxies and AGN. Furthermore, such areal coverage allows the environments to be fully accounted for, thereby linking the single halo to the two-halo terms in the halo occupation distribution. Surveys at radio wavelengths have begun to lag behind those at other wavelengths, especially in this medium-deep survey tier. However, the survey speed offered by the JVLA means that we can now reach a point where we can begin to obtain commensurate data at radio wavelengths to those which already exists from the X-ray through to the far-infrared over ~10 square degrees. We therefore present the case for a 10 square degree survey to 1.5uJy at L-band in A or B Array, requiring ~4000 hours to provide census of star-formation and AGN-accretion activity in the Universe. For example, the observations will allow galaxies forming stars at 10Msolar/yr to be detected out to z~1 and luminous infrared galaxies (1000Msolar/yr to be found out to z~6. Furthermore, the survey area ensures that we will have enough cosmic volume to find these rare sources at all epochs. The bandwidth will allow us to determine the polarisation properties galaxies in the high-redshift Universe as a function of stellar mass, morphology and redshift.