scholarly journals Overview of Uncovered and Suspected Large-scale Structures behind the Milky Way

1999 ◽  
Vol 16 (1) ◽  
pp. 53-59 ◽  
Author(s):  
Renée C. Kraan-Korteweg ◽  
Patrick A. Woudt
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Milky Way ◽  
Far Infrared ◽  
Observational Evidence ◽  
Large Scale Structures ◽  
Galaxy Distribution ◽  
Wide Range ◽  
Scale Structures ◽  
Zone Of Avoidance

AbstractVarious dynamically important extragalactic large-scale structures in the local Universe lie behind the Milky Way. Most of these structures (predicted and unexpected) have only recently been made ‘visible’ through dedicated deep surveys at various wavelengths. The wide range of observational searches (optical, near infrared, far infrared, radio and X-ray) for galaxies in the Zone of Avoidance (ZOA) will be reviewed and the uncovered and suspected large-scale structures summarised. Particular emphasis is given to the Great Attractor region where the existence of yet another cluster is suspected (Woudt 1998). Predictions from reconstructions of the density field in the ZOA are discussed and compared with observational evidence. Although no major structures are predicted out to about v ≲ 10,000 km s−1 for which no observational evidence exists, the comparison between reconstructed density fields and the observed galaxy distribution remain important as they allow derivations of the density and biasing parameters.

scholarly journals Large Scale Structure in the Local Universe — The 2MASS Galaxy Catalog

2004 ◽  
Vol 21 (4) ◽  
pp. 396-403 ◽  
Author(s):  
Thomas Jarrett
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Local Universe ◽  
Extended Source ◽  
Large Scale Structures ◽  
Photometric Redshift ◽  
Sky Survey ◽  
Nearby Galaxies ◽  
Scale Structures ◽  
Zone Of Avoidance

AbstractUsing twin ground-based telescopes, the Two-Micron All Sky Survey (2MASS) scanned both equatorial hemispheres, detecting more than 500 million stars and resolving more than 1.5 million galaxies in the near-infrared (1–2.2 μm) bands. The Extended Source Catalog (XSC) embodies both photometric and astrometric whole sky uniformity, revealing large scale structures in the local Universe and extending our view into the Milky Way's dust-obscured ‘Zone of Avoidance’. The XSC represents a uniquely unbiased sample of nearby galaxies, particularly sensitive to the underlying, dominant, stellar mass component of galaxies. The basic properties of the XSC, including photometric sensitivity, source counts, and spatial distribution, are presented here. Finally, we employ a photometric redshift technique to add depth to the spatial maps, reconstructing the cosmic web of superclusters spanning the sky.

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

2019 ◽  
Vol 489 (2) ◽  
pp. 2907-2922 ◽  
Author(s):  
A C Schröder ◽  
L Flöer ◽  
B Winkel ◽  
J Kerp
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Dwarf Galaxies ◽  
High Rate ◽  
Infrared Images ◽  
Large Scale Structures ◽  
The Past ◽  
Northern Zone ◽  
Scale Structures ◽  
Zone Of Avoidance

ABSTRACT We present a catalogue of galaxies in the northern Zone of Avoidance (ZoA), extracted from the shallow version of the blind H i survey with the Effelsberg 100 m radio telescope, EBHIS, that has a sensitivity of 23 mJy beam−1 at 10.24 km s−1 velocity resolution. The catalogue comprises 170 detections in the region δ ≥ −5° and |b| < 6°. About a third of the detections (N = 67) have not been previously recorded in H i. While 29 detections have no discernible counterpart at any wavelength other than H i, 48 detections (28 per cent) have a counterpart visible on optical or near-infrared images but are not recorded as such in the literature. New H i detections were found as close as 7.5 Mpc (EZOA J2120+45), and at the edge of the Local Volume, at 10.1 Mpc, we have found two previously unknown dwarf galaxies (EZOA J0506+31 and EZOA J0301+56). Existing large-scale structures crossing the northern ZoA have been established more firmly by the new detections, with the possibility of new filaments. We conclude that the high rate of 39 per cent new H i detections in the northern ZoA, which has been extensively surveyed with targeted observations in the past, proves the power of blind H i surveys. The full EBHIS survey, which will cover the full northern sky with a sensitivity comparable to the HIPASS survey of the southern sky, is expected to add many new detections and uncover new structures in the northern ZoA.

scholarly journals DENIS Observations of Multibeam Galaxies in the Zone of Avoidance

1999 ◽  
Vol 16 (1) ◽  
pp. 42-47 ◽  
Author(s):  
A. Schröder ◽  
R. C. Kraan-Korteweg ◽  
G. A. Mamon
Keyword(s):  
Velocity Field ◽  
Large Scale ◽  
Near Infrared ◽  
Milky Way ◽  
Selection Effects ◽  
Galaxy Distribution ◽  
The Galaxy ◽  
Multi Wavelength ◽  
Zone Of Avoidance ◽  
Fisher Relation

AbstractRoughly 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various surveys are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA), but all suffer from (different) limitations and selection effects. We illustrate the promise of using a multi-wavelength approach for extragalactic large-scale studies behind the ZOA, i.e. a combination of three surveys, optical, systematic blind HI and near-infrared (NIR), which will allow the mapping of the peculiar velocity field in the ZOA through the NIR Tully–Fisher relation. In particular, we present here the results of cross-identifying HI-detected galaxies with the DENIS NIR survey, and the use of NIR colours to determine foreground extinctions.

scholarly journals First Results from the HI Parkes Zone of Avoidance Survey

1999 ◽  
Vol 171 ◽  
pp. 331-333
Author(s):  
P.A. Henning ◽  
L. Staveley-Smith ◽  
R.C. Kraan-Korteweg ◽  
E.M. Sadler
Keyword(s):  
Large Scale ◽  
Milky Way ◽  
Large Scale Structures ◽  
First Results ◽  
Nearby Galaxies ◽  
Scale Structures ◽  
Zone Of Avoidance ◽  
Blind Search

AbstractThe HI Parkes Zone of Avoidance Survey is a 21 cm blind search with the multibeam receiver on the 64-m radiotelescope, looking for galaxies hidden behind the southern Milky Way. The first phase of the survey has uncovered 107 galaxies, two-thirds of which were previously unknown. The addition of these galaxies to existing extragalactic catalogs allows the connectivity of large-scale structures across the Zone of Avoidance within 3500 km s−1 to become evident. No nearby hidden “Andromeda-class” object was uncovered. Our census of the most dynamically important HI-bearing nearby galaxies is now complete, at least for those objects whose HI profiles are not totally buried in the Galactic HI signal. The full survey is ongoing, and is expected to produce a catalog of thousands of objects when it is finished.

scholarly journals Connection of large-scale structures of the galaxy distribution behind the southern Milky Way

1993 ◽  
Vol 262 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Toru Yamada ◽  
Tadafumi Takata ◽  
Thomas Djamaluddin ◽  
Akihiko Tomita ◽  
Kentaro Aoki ◽  
...  
Keyword(s):  
Large Scale ◽  
Milky Way ◽  
Large Scale Structures ◽  
Galaxy Distribution ◽  
The Galaxy ◽  
Scale Structures

scholarly journals Coherent large-scale structures from the linearized Navier–Stokes equations

2019 ◽  
Vol 873 ◽  
pp. 89-109 ◽  
Author(s):  
Anagha Madhusudanan ◽  
Simon. J. Illingworth ◽  
Ivan Marusic
Keyword(s):  
Large Scale ◽  
Eddy Viscosity ◽  
Stokes Equations ◽  
Turbulent Channel Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Large Scale Structures ◽  
Viscosity Profile ◽  
Wide Range ◽  
Scale Structures

The wall-normal extent of the large-scale structures modelled by the linearized Navier–Stokes equations subject to stochastic forcing is directly compared to direct numerical simulation (DNS) data. A turbulent channel flow at a friction Reynolds number of $Re_{\unicode[STIX]{x1D70F}}=2000$ is considered. We use the two-dimensional (2-D) linear coherence spectrum (LCS) to perform the comparison over a wide range of energy-carrying streamwise and spanwise length scales. The study of the 2-D LCS from DNS indicates the presence of large-scale structures that are coherent over large wall-normal distances and that are self-similar. We find that, with the addition of an eddy viscosity profile, these features of the large-scale structures are captured by the linearized equations, except in the region close to the wall. To further study this coherence, a coherence-based estimation technique, spectral linear stochastic estimation, is used to build linear estimators from the linearized Navier–Stokes equations. The estimator uses the instantaneous streamwise velocity field or the 2-D streamwise energy spectrum at one wall-normal location (obtained from DNS) to predict the same quantity at a different wall-normal location. We find that the addition of an eddy viscosity profile significantly improves the estimation.

scholarly journals Unveiling a connection between large-scale structures behind the southern Milky Way

1997 ◽  
Vol 287 (2) ◽  
pp. 472-480 ◽  
Author(s):  
H. Di Nella ◽  
W. J. Couch ◽  
Q. A. Parker ◽  
G. Paturel
Keyword(s):  
Large Scale ◽  
Milky Way ◽  
Large Scale Structures ◽  
Scale Structures

scholarly journals An Obscured Galaxy Redshift Survey with FLAIR

1997 ◽  
Vol 14 (1) ◽  
pp. 126-126 ◽  
Author(s):  
K. Wakamatsu ◽  
M. Malkan ◽  
Q. A. Parker ◽  
H. Karoji
Keyword(s):  
Large Scale ◽  
Wall Structure ◽  
Galactic Centre ◽  
Large Scale Structures ◽  
Sky Survey ◽  
Centre Region ◽  
Redshift Survey ◽  
Galaxy Redshift ◽  
Scale Structures ◽  
Zone Of Avoidance

A problem for studies of large scale structures in nearby space (cz < 10,000 km s-1) is the presence of the Zone of Avoidance which is so large and wide on the sky that potentially important clusters and voids remain undetected. A prime example was the Ophiuchus cluster discovered by Wakamatsu and Malkan (1981) as a heavily obscured cD cluster close to the Galactic centre region (l = 0·5°, b = +9·5°). It is the second brightest X-ray cluster after Perseus. A hidden galaxy survey was performed by visually searching ESO/SERC Sky Survey (R and J) copy films of the region centred at l = 355°, b = +10° finding more than 4000 galaxies in six fields. Several irregular clusters adjacent to Ophiuchus were found forming a supercluster which may be connected to the Hercules supercluster by a wall structure parallel to the local supergalactic plane (Wakamatsu et al. 1994). In front of this supercluster, an 'Ophiuchus Void' is suggested (cz = 4,500 km s-1). The Ophiuchus supercluster at cz = 8,500 km s-1 is similar to the Hercules supercluster (cz = 11,000 km s-1), and extends north toward the latter supercluster.

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