Supplementing the 2MRS survey: The 2MZoA catalogue

TL;DR

This paper introduces an extended galaxy catalogue in the Zone of Avoidance, supplementing the 2MRS survey to enable more complete all-sky studies of large-scale structures and cosmic flows.

Contribution

It presents a new, more complete low-latitude galaxy catalogue with improved extinction correction, enhancing the 2MRS survey for better large-scale structure analysis.

Findings

Catalogue contains 6899 galaxies, 75% redshift completeness.

Adding extinction correction recovers 1083 obscured galaxies.

No dependence of correction factor on Galactic coordinates found.

Abstract

We present a homogeneous 2MASX galaxy catalogue at low Galactic latitudes (|b| <= 10.0 deg, called Zone of Avoidance, ZoA) which is complete to a Galactic extinction-corrected magnitude of Ko <= 11.75 mag. Also included are galaxies at higher latitudes in areas of high foreground extinctions (E(B-V) > 0.95). This catalogue supersedes the previously presented bright 2MZoA catalogue which was only complete to Ko < 11.25 mag. It fully complements the 2MASS Redshift Survey (2MRS) galaxy catalogue, which has the same magnitude limit but excludes high extinction regions. The combination of the two catalogues, the extended 2MRS or e2MRS, is is a uniquely whole sky redshift survey and forms a sound basis for studies of large-scale structures, flow fields and extinction across the ZoA. The here presented catalogue comprises 6899 galaxies with 6757 galaxies at low latitudes and 142 galaxies in highly obscured high-latitude areas. The completion rate in redshifts is almost 75%. The catalogue is complete up to star density levels of at least log N_*/deg^2 < 4.3, but the completion rate of the fainter part is affected by foreground extinction at all levels. This can be rectified by using a diameter-dependent extinction correction, adding 1083 highly obscured but apparently faint galaxies (with Ko > 11.75 mag and Ko,d <= 11.75 mag) to the sample. This extended sample shows good completion rates with extinction up to at least AK < 1.3 mag. Omission of such a diameter-dependent extinction correction may lead to a biased flow field even at intermediate extinction values as found in the 2MRS survey. As in our previous investigations, we do not find a dependence of the correction factor f=0.86 to the extinction maps on Galactic longitudes or latitudes, but note a possible influence by cosmic variance.