The 2MASS Redshift Survey in the Zone of Avoidance

Lucas M Macri,María Victoria Alonso,Thomas H Jarrett,Emilio E Falco,Jessica D Mink,Trystan Lambert,Michael Calkins,Perry Berlind,Pirin Erdoğdu,Renée C Kraan-Korteweg

doi:10.3847/1538-4365/ab465a

Abstract

Abstract The Two Micron All-Sky Survey (2MASS) Redshift Survey was started two decades ago with the goal of mapping the three-dimensional distribution of an all-sky flux-limited (K s < 11.75 mag) sample of ∼45,000 galaxies. Our first data release presented an unprecedented uniform coverage for most of the celestial sphere, with redshifts for ∼98% of our sample. However, we were missing redshifts for ∼18% of the catalog entries that were located within the “Zone of Avoidance” ( )—an important region of the sky for studies of the large-scale structure and cosmic flows. In this second and final data release, we present redshifts for all 1041 2MRS galaxies that previously lacked this information, as well as updated measurements for 27 others.

Highlights

We were missing redshifts for ∼ 18% of the catalog entries that were located within the “Zone of Avoidance” (|b| < 10◦) – an important region of the sky for studies of large-scale structure and cosmic flows
Decades of concerted efforts have yet to resolve the tension between local cosmic flows and cosmology: what gives rise to our peculiar motion, and is it consistent with ΛCDM? Answering these question requires knowledge of the local cosmography and the peculiar velocity field
The persistent discrepancies in the derived Local Group motion are thought to be due to incomplete mapping of large-scale structures at low Galactic latitudes, in the so-called “Zone of Avoidance” (ZoA; Kraan-Korteweg & Lahav 2000; Loeb & Narayan 2008)

Summary

INTRODUCTION

Decades of concerted efforts have yet to resolve the tension between local cosmic flows and cosmology: what gives rise to our peculiar motion, and is it consistent with ΛCDM? Answering these question requires knowledge of the local cosmography (based on the observed distribution of luminous matter) and the peculiar velocity field (which originates from the combined distribution of both luminous and dark matter). The 2MASS Tully-Fisher survey (2MTF; Masters et al 2008) obtained high-quality 21cm linewidths for 493 2MRS galaxies which, combined with measurements from the literature, have yielded a catalog of 2062 distances based on the Tully-Fisher relation (Tully & Fisher 1977) and corresponding peculiar velocities (Hong et al 2019). These efforts are complementary to those of the 6dFGS project (Jones et al 2009), which obtained redshifts for a deeper (Ks 12.5 mag) sample of 2MASS galaxies (but was limited to the Southern hemisphere) and used the fundamental plane of elliptical galaxies (Dressler et al 1987) to derive distances (Magoulas et al 2012)

OBSERVATIONS

ANALYSIS AND RESULTS

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