The 2MASS Redshift Survey in the Zone of Avoidance

Abstract

The 2MASS Redshift Survey was started two decades ago with the goal of mapping the threedimensional distribution of an all-sky flux-limited (K s < 11.75 mag) sample of ∼ 45, 000 galaxies. Our first data release (Huchra et al. 2012) 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" (|b| < 10 • ) -an important region of the sky for studies of large-scale structure and cosmic flows.In this second and final data release, we present redshifts for all 1,041 2MRS galaxies that previously lacked this information, as well as updated measurements for 27 others.

The 2MASS redshift survey galaxy group catalogue derived from a graph-theory based friends-of-friends algorithm

“…In Fig. 15 we can indeed confirm that the galaxies not only map out an extension of the Perseus-Pisces chain from l ≈ 150 • to l ≈ 160 • (as discussed in Macri et al 2019) but so do the galaxy groups which later connect to Lynx at l ≈ 170 • (Ramatsoku et al 2016;Kraan-Korteweg et al 2018;Macri et al 2019). There are also several new group candidates at this crossing, further emphasising the importance of filling in the ZoA.…”

“…The second crossing of the Perseus-Pisces chain, at l ≈ 90 • , also includes several new groups and is well defined in our group catalogue. Macri et al (2019) also highlights a surprising new density at (l, b) ≈ (100 • , −5 • ). In Figure 15 we see that there are groups in this over-density, several of which have been identified as new and therefore may be worth additional follow up observations.…”

“…We also include a catalogue consisting of all the galaxies that are member of a group in Table 3. This catalogue includes the 2MASS ID, α, δ, l, b of each galaxy as given in Macri et al (2019), as well as our calculated v cmb , Group ID from Table 1 and Sub ID from Table 2. A random sub-sample of galaxies are shown in Table 3 for reference.…”

“…The whole-sky nature (and diminished ZoA impact) of 2MASX enabled the 2MASS Redshift Survey (2MRS; Huchra et al 2005Huchra et al , 2012Macri et al 2019), a twentyyear concerted effort to measure the redshifts of all ∼ 45000 2MASX sources with K o s < 11. m 75 and thus obtain the most comprehensive (coverage-wise) whole-sky redshift survey to date. A preliminary data release with a magnitude limit of K o s < 11. m 25 consisted of ∼ 24000 galaxies (Huchra et al 2005).…”

“…Aitoff projection in Galactic coordinates of the complete 2MRS. Black and red dots represent the galaxies with redshifts fromHuchra et al (2012) andMacri et al (2019), respectively. The latter have been scaled for visibility.…”