The Nançay H i Zone of Avoidance survey of 2MASS bright galaxies

Abstract

To complement the 2MASS Redshift Survey (2MRS) and the 2MASS Tully-Fisher survey (2MTF) a search for 21cm H I line emission of 2MASS bright galaxy candidates has been pursued along the dust-obscured plane of the Milky Way with the 100m Nançay Radio Telescope. For our sample selection we adopted an isophotal extinction-corrected K s -band magnitude limit of K o s = 11. m 25, corresponding to the first 2MRS data release and 2MTF, for which the 2MASX completeness level remains fairly constant deep into the Zone of Avoidance (ZoA). About one thousand galaxies without prior redshift measurement accessible from Nançay (Dec > −40 • ) were observed to an rms noise level of ∼ 3 mJy for the velocity range −250 to 10 600 km s −1 . This resulted in 220 clear and 12 marginal detections of the target sample. Only few detections have redshifts above 8000 km s −1 due to recurring radio frequency interference (RFI). A further 29 detections and 6 marginals have their origin in nontarget galaxies in the telescope beam. The newly detected galaxies are on average considerably more H I-rich (mostly 10 9 − 10 10 M ⊙ ) compared to systematic (blind) H I surveys. The H I detections reveal various new filaments crossing the mostly uncharted northern ZoA (e.g. at ℓ ∼ 90 • , 130 • , 160 • ), whilst consolidating galaxy agglomerations in Monoceros and Puppis (ℓ ∼ 220 • , 240 • ). Considerably new insight has been gained about the extent of the Perseus-Pisces Supercluster through the confirmation of a ridge (ℓ ∼ 160 • ) encompassing the 3C129 cluster that links Perseus-Pisces to Lynx, and the continuation of the second Perseus-Pisces arm (ℓ ∼ 90 • ) across the ZoA.

EZOA – a catalogue of EBHIS H i-detected galaxies in the northern Zone of Avoidance

“…We compared the extracted H i parameters with published values. We found reasonable overlap with HIPASS (N = 38), HIZOA (N = 32) and Nançay radio telescope measurements (NRT; N = 35) (Kraan-Korteweg et al 2018;Paturel et al 2003;Theureau et al 1998;Chamaraux et al 1990;Martin et al 1990). For the comparison we excluded obviously confused cases.…”

“…(5) The tail-end of the Perseus-Pisces filament that crosses the ZoA in Cygnus at l ∼ 90 • and which has been discussed extensively by Ramatsoku et al (2016) and Kraan-Korteweg et al (2018), has also been strengthened despite the drop in sensitivity of our survey for redshifts above 4000 km s −1 .…”

“…The distribution of line widths measured at half peak, w50, is highly skewed with a peak at ∼ 100 km s −1 , a mean of 176 km s −1 and a median of 146 km s −1 , very similar to the HIZOA-S survey (with a mean and median of 163 km s −1 and 147 km s −1 , respectively). It is interesting to note that the line width distribution of a pointed survey of NIR-selected targets, as, for example, presented by (Kraan-Korteweg et al 2018), shows a more Gaussian distribution with a higher mean of 288 km s −1 that is the same as the median, as shown in Fig. 5 as the filled green histogram.…”

“…J2000+18: The flux determination may be affected by an RFI in the range 3900 − 4000 km s −1 which was not completely removed during the reduction process. J2001+26: There are three galaxies in the field, one of which (2MASX J20010969+2655338) was observed by Kraan-Korteweg et al (2018) with the NRT but not detected. The other two galaxies are not listed in the literature: the galaxy at (RA,Dec) = (20:01:26.4,+26:59:40) is diffuse and matches the H i parameters well, while the galaxy at (RA,Dec) = (20:01:26.7,+26:55:36) at a larger distance of 3.…”

The 2MASS Redshift Survey in the Zone of Avoidance

“…The feature connects to a ridge in the ZoA, which encompasses the 3C 129 cluster that links PP to Lynx (see Ramatsoku et al 2016;Kraan-Korteweg et al 2018). It also traces the continuation of the second PP arm (l ∼ 90 • ) closer to the ZoA, connecting to a filamentary extension across the ZoA found with H I observations (Kraan-Korteweg et al 2018). The concentration around l ∼ 100 • , b ∼ −5 • (seen in green in Fig.…”