WMAP extragalactic point sources as potential Space VLBI calibrators

TL;DR

This paper identifies new bright, compact extragalactic radio sources from the WMAP catalogue suitable for mm-VLBI and Space VLBI, enhancing the pool of potential calibrators for high-frequency radio astronomy.

Contribution

It compiles a new list of 37 previously unexplored VLBI sources at 86 GHz, increasing the known mm-VLBI sources by nearly 25%, and assesses their suitability as calibrators for future space missions.

Findings

Identified 37 new mm-VLBI candidate sources with flux density >1 Jy.

These sources increase the known mm-VLBI sources by about 25%.

Potential use as phase-reference calibrators for the ASTRO-G mission.

Abstract

The point source list of the Wilkinson Microwave Anisotropy Probe (WMAP) is a uniform, all-sky catalogue of bright sources with flux density measurements at high (up to 94 GHz) radio frequencies. We investigated the five-year WMAP list to compile a new catalogue of bright and compact extragalactic radio sources to be potentially studied with Very Long Baseline Interferometry at millimeter wavelengths (mm-VLBI) and Space VLBI (SVLBI). After comparing the WMAP data with the existing mm-VLBI catalogues, we sorted out the yet unexplored sources. Using the 41, 61 and 94 GHz WMAP flux densities, we calculated the spectral indices. By collecting optical identifications, lower-frequency radio flux densities and VLBI images from the literature, we created a list of objects which have not been investigated with VLBI at 86 GHz before. With total flux density at least 1 Jy and declination above -40 degree, we found 37 suitable new targets. It is a nearly 25% addition to the known mm-VLBI sources. Such objects are also potentially useful as phase-reference calibrators for the future Japanese SVLBI mission ASTRO-G at its highest observing frequency (43 GHz). The phase-referencing capability of ASTRO-G would allow long integrations and hence better sensitivity for observing faint target sources close to suitable phase calibrators in the sky.