Wideangle Tailed Radio Galaxies

Wide- angle tails (WAT), originally defined by Owen & Rudnick (1976), are V-shaped radio sources consisting of two, straight and narrow, jets that flare into broad tails. Like in NATs, the tails extend in a common direction, although forming a much larger angle between them. They are generally associated with D cD or giant ellipticals at the optical centers of clusters (O'Donoghue et al. 1990). Despite the fact that D and cD galaxies are most likely to be found in cooling flow regions, WATs...

Radio Sources And The Butcheroemler Effect

One of the most important examples of the impact of environment on the evolution of galaxies is the discovery made by Butcher & Oemler (1978) that a large fraction of galaxies in rich distant clusters (z > 0.3) have abnormally blue colours. This is the so called Butcher-Oemler effect (B-O). Subsequent studies, based on narrow band photometry and spectroscopy, provided the information that this population of blue objects includes both galaxies with emission line spectra typical of ongoing...

Xray Diagnostics For Cluster Mergers

While the study of cluster mergers is quite difficult at optical wavelength (see Girardi & Biviano, this volume), deep X-ray images can provide more detailed insight into the merger configuration. The X-ray emission originates from hot intracluster gas which is thermally emitting in X-rays and which is trapped in the gravitational potential well of the clusters. The X-ray emission is proportional to the square of the density (emission measure) of the hot gas and the X-ray surface brightness...

Logio Xlogo X

Collisional gas velocity (left) and density (right) structure from the self-similar infall solution of Bertschinger (1985). of features characterize the structure. The radial coordinate is scaled to the zero-velocity surface, or turn-around radius rta(t) oc t8 9, so the mean radial velocity is zero at X r rta(t) l. Interior to this radius, an infall regime, where gas is contracting, extends to A 0.3. At this point, infalling material is halted by outward propagating shock front....

Multiple Cold Fronts In A2142

A2142 is a hot (kT 9 keV), X-ray-luminous cluster at a redshift of z 0.089. Two bright elliptical galaxies lie near the center and are aligned in the general direction of the X-ray brightness elongation. Furthermore, the line-of-sight velocities of these galaxies differ by 1840 km s_1 (Oegerle et al. 1995), consistent with an unrelaxed cluster. In earlier work, the ROSAT PSPC image was used to argue for a late merger stage (Buote & Tsai 1996) and Henry & Briel (1996) used a ROSAT...

Substructure And Cosmology 41 Accretion From The

In hierarchical clustering cosmological scenarios clusters of galaxies form by accretion of subunits. Numerical simulations show that clusters form preferentially through anisotropic accretion of subclusters along large scale filaments (West et al. 1991 Katz & White 1993 Cen & Ostriker 1994 Colberg et al. 1998, 1999). The infall of matter onto clusters arises from clumpy, inhomogeneous, filaments and sheets (Colberg et al. 1999). The signature of this anisotropic cluster formation is the...

Object Index

A85, 13, 16, 21, 32, 54, 58-59, 81, 88-89, 111, 215 A87, 58-59 A89, 58-59 A91, 58 A426, 55, 123-124, 128, 169, 176, 199, 201 A521, 50, 58, 60, 65-66, 84-85 A528, 58, 60 A548, 42, 48 A562, 175 A665, 13, 120-122, 207-208, 235 A697, 66 A754, 56-57, 65, 136, 139-141, 208, 223 A1060, 57 A1300, 208 A1367, 46, 59, 83-84, 187, 199, 204 A1656, 27, 29, 32-34, 41, 46, 50, 55, 57, 59, 65-69, 80, 83, 99, 110, 135-139, 145-146, 150, 167, 170, 187, 189-190, 198-199, 201, 203-204, 208, 211, 215-220, 222, 235,...