Large Scale Structure in the Local Universe:
The WISE Galaxy Catalog

Our understanding of the origin and time evolution of the Universe has been fundamentally transformed with seminal redshift, distant supernovae and cosmic microwave background surveys. The focus has shifted to the distribution and nature of dark matter and dark energy that drive the dynamics of the expanding cosmos. The study of the local Universe, including its peculiar motions and its clustering on scales exceeding 100 Mpc, is an essential ingredient in the connection between the origin of structure in the early Universe and the subsequent formation of galaxies and their evolution to the state we observe today. Key issues include the location and velocity distribution of galaxies, leading to the mass-to-light relationship between what is observed and what is influencing the mass density field.

The Cosmic Web

Uniform and continuous maps of the sky uniquely provide the "big picture" context for analysis and interpretation of data concerning galaxy clusters, large scale structure and the density of matter in the Universe. Like the 2MASS Galaxy Catalog, the WISE Galaxy Catalog will provide a broad framework for studying the physical connection between the local Universe (Milky Way, Local Group, Local Supercluster, "Great Wall", etc) and the distant Universe where galaxies and the cosmic web first formed.

Panoramic view of the entire near-infrared sky reveals the distribution of galaxies beyond the Milky Way. The image is derived from the 2MASS Extended Source Catalog (XSC)--more than 1.5 million galaxies, and the Point Source Catalog (PSC)--nearly 0.5 billion Milky Way stars. The galaxies are color coded by "redshift," photo- metrically deduced from the K band (2.2 m) or as given in the NASA Extragalactic Database (NED). Blue are the nearest sources (z < 0.01); green are at moderate distances (0.01 < z < 0.04) and red are the most distant sources that 2MASS resolves (0.04 < z < 0.1). The map is projected with an equal area aitoff in the Galactic system (Milky Way at center). Image from Jarrett (2004).

WISE Universe

2MASS mapped the entire sky at near-infrared wavelengths, resolving galaxies out to distances of z ~ 0.1 (D = 400 Mpc), constructing an intricate web of large scale structures (LSS) that arch across the sky (see Figure above; Jarrett 2004). 2MASS is sensitive to intrinsically luminous early type galaxies, but begins to become incomplete for most normal galaxies beyond z ~ 0.06. Deeper, more focused surveys of LSS (e.g., 2dF and SDSS) reveal a cosmic web that continuously stretches from the Local Supercluster to well beyond 600 Mpc and the 2MASS universe. WISE, by virtue of its near-infrared 3.5-micron band, and its mid-infrared bands at 12 and 24 microns, is sensitive to both early-type ellipticals and late-type spiral galaxies. The WISE galaxy catalog, containing both resolved and unresolved sources, should be complete out to distances of z ~ 0.5 (D = 2000 Mpc), thus greatly expanding the volume, >5³, of the Local Universe that 2MASS probed. The four bands of WISE, in conjunction with available photometric measurements at other wavelengths (e.g., GALEX, 2MASS, IRAS, and in the optical window, using photographic measurements from the USNO astrometric catalogs), provide adequate information to derive "photometric" redshifts, and thereby bring physical dimension to the WISE universe. The resultant cosmic web will be a far more intricate and detailed picture of the complete Local Universe than has ever been constructed, bridging the gap between the current state of the universe and the epoch of active galaxy formation.

Reference

• 2MASS Universe