The Ursa Major supercluster of galaxies: II. The structure and peculiar velocities

Kormendy’s relation (μ_e-logR _e) is used to investigate the structure of the compact Ursa Major supercluster of galaxies (11^h30^m+55°, cz=18 000 km s^?1); this relation allows the distances of early-type galaxies to be estimated. The relative distances of 13 clusters in the supercluster and their peculiar velocities are determined with a mean statistical accuracy of 6%. In general, the supercluster obeys the Hubble relation between radial velocity and distance. However, there is reason to suggest that the supercluster consists of two subsystems with mean radial velocities of 16 200 and 19 700 km s^?1. For a velocity dispersion in the subsystems of ～1100 km s^?1, the fact that each of them is gravitationally bound is not ruled out.     

Detailed study of the Ursa Major supercluster of galaxies using the 2MASS and SDSS Catalogs

We study the infrared (K _s band) properties of clusters of galaxies in the Ursa Major supercluster using data from 2MASS (Two-Micron All-Sky Survey) and SDSS (Sloan Digital Sky Survey). We identified three large filaments with mean redshifts of z = 0.051, 0.060, and 0.071. All clusters of the supercluster are located in these filaments. We determined the total K _s-band luminosities and masses for 11 clusters of galaxies within comparable physical regions (within a radius R ₂₀₀ close to the virial radius) using a homogeneous method. We constructed a combined luminosity function for the supercluster in this region, which can be described by the Schechter function with the following parameters: M _K ^* = ?24.50 and α = ?0.98. The infrared luminosities of the clusters of galaxies correlate with their masses; the M/L _K ratios of the systems increase with their masses (luminosities), with most of the Ursa Major clusters of galaxies (particularly the richer ones) closely following the relations derived previously for a large sample of clusters and groups of galaxies. The total mass-to-infrared-luminosity ratio is 52 M _⊙/L _⊙ for six Abell clusters and 49M _⊙/L _⊙ for all of the clusters, except Anon2.     

Analysis of the RC catalog sample in the region overlapping with the regions of the FIRST and SDSS surveys: I. Identification of sources with the VLSS, TXS, NVSS, FIRST, and GB6 catalogs

Radio sources of the RC catalog produced in 1980–1985 at RATAN-600 radio telescope based on a deep survey of a sky strip centered on the declination of the SS433 source are optically identified in the region overlapping with FIRST and SDSS surveys (about 132?° large). The NVSS catalog was used as the reference catalog for refining the coordinates of the radio sources. The morphology is found for about 75% of the objects of the sample and the ratio of single, double and multicomponent radio sources is computed based on FIRST radio maps. The 74, 365, 1400, and 4850MHz data of the VLSS, TXS, NVSS, FIRST, and GB6 catalogs are used to analyze the shape of the spectra.     

RC J0105+0501: A radio galaxy with redshift z≈3.5

We study the radio galaxy RC J0105+0501 by using observations with RATAN-600, VLA, and 6-m Special Astrophysical Observatory telescope. The radio source has a structure resembling the FRII type and the spectral index α=1.23; it is identified with a faint galaxy of $22\mathop .\limits^m 8$ in R _c . The optical object is $1\mathop .\limits^m 5$ brighter in V than it is in B and has an extended structure, which we interpret as intense Lyα line emission with redshift z≈3.5 and a continuum depression in the adjacent short-wavelength region. Based on BVR _c I _c photometry, we also estimated the age of the stellar population of the radio galaxy.     

Spectroscopy of RC sources

The results of spectroscopic observations of the host galaxies of objects in the RC catalog (the “Big Trio” program) obtained using the new SCORPIO spectrograph of the Special Astrophysical Observatory are presented. The spectroscopic redshifts of the objects are compared with their photometric color redshifts, and the errors in the latter are estimated. Based on BV RI observations obtained on the 6-m telescope of the SAO, the errors for the population of powerful radio galaxies are close to those found previously for radio quiet galaxies (about 10–20%). The detection of Ly α in the B filter in RC 1626+0448 is confirmed. This object is the second spectrally studied FR II radio source from the RC catalog to have a redshift z>2.5. Star formation in its host galaxy began at a redshift z>3.3. This first use of the new SCORPIO spectrograph demonstrates its promise for studies of very distant steep-spectrum radio galaxies brighter than 23^m–24^m in V.     

On the photometric redshift estimates for FR II radio galaxies

Using the photometric data on FR II radio galaxies obtained during the Big Trio program and data from other sources, we confirmed the stable correlation between the spectroscopic and photometric redshifts up to z ～ 4, determined from the evolutionary synthetic spectra of elliptical galaxies. This is confirmation of the theoretical predictions of the existence of a stellar population at high redshifts and its subsequent evolution corresponding to the population of giant elliptical galaxies.     

Seasonal and Year-to-Year Variations of Phytoplankton Primary Production in the Rybinsk Reservoir: The Effect of Weather and Climate Variations

Water Resources - The seasonal and long-term dynamics of phytoplankton primary production has been studied in the Rybinsk Reservoir (Upper Volga) in 2005–2014. A positive correlation has been...