Spectrophotometry of faint cluster galaxies and the Hubble diagram - an approach to cosmology

1975 ◽  
Vol 195 ◽  
pp. 255 ◽  
Author(s):  
J. E. Gunn ◽  
J. B. Oke
Keyword(s):  
Hubble Diagram ◽  
Cluster Galaxies

scholarly journals The K-Band Hubble Diagram for X-Ray Selected Brightest Cluster Galaxies

1998 ◽  
Vol 179 ◽  
pp. 339-341
Author(s):  
R.G. Mann ◽  
C.A. Collins
Keyword(s):  
Star Formation ◽  
List Type ◽  
Type Number ◽  
Hubble Diagram ◽  
Technical Problems ◽  
X Ray ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
The Absolute ◽  
Small Dispersion

The Hubble (magnitude-redshift) diagram for brightest cluster galaxies (BCGs) is a classic cosmological tool, widely studied because of the remarkably small dispersion (∼ 0.3 mag) in the absolute optical magnitudes of low redshift BCGs (Postman and Lauer 1995). Extending the BCG Hubble diagram to higher redshifts would greatly enhance its role as a cosmological probe, but this has been frustrated by several technical problems: – the conventional means of cluster selection in the optical become increasingly compromised by projection effects at z > 0.1– at higher redshifts the interpretation of optical magnitudes becomes increasingly complicated by the effects of possible star formation.

scholarly journals The Redshift-Magnitude Relation for Radio Galaxies

1977 ◽  
Vol 74 ◽  
pp. 279-293 ◽  
Author(s):  
Harding E. Smith
Keyword(s):  
Radio Galaxies ◽  
Hubble Diagram ◽  
Great Expectations ◽  
Cluster Galaxies ◽  
The Past ◽  
Near Future ◽  
Luminosity Evolution ◽  
Test Objects ◽  
Radio Power

We examine the Hubble diagram for radio galaxies and compare radio galaxies and first-ranked cluster galaxies as cosmological test objects. Radio source identification programs are now producing reliable identifications with galaxies as faint as V ≈ 23 and spectroscopy of these objects has already resulted in the discovery of galaxies with redshifts as high as 0.75, thus there are great expectations for progress in the near future. As in the past, indeterminate corrections, notably luminosity evolution and a possible correlation between radio power and optical luminosity, preclude the determination of qo.

scholarly journals The K-Band Hubble Diagram for the Brightest Cluster Galaxies: A Test of Galaxy Formation Models

1999 ◽  
Vol 186 ◽  
pp. 407-407
Author(s):  
A. Aragón-Salamanca ◽  
C.M. Baugh ◽  
G. Kauffmann
Keyword(s):  
Galaxy Formation ◽  
Stellar Mass ◽  
Hubble Diagram ◽  
Redshift Range ◽  
Cluster Galaxies ◽  
Brightest Cluster Galaxies ◽  
Galaxy Formation And Evolution ◽  
Absolute Magnitudes ◽  
Luminosity Evolution ◽  
K Band

We analyze the K-band Hubble diagram for a sample of brightest cluster galaxies (BCGs) in the redshift range 0 < z < 1. We confirm that the scatter in the absolute magnitudes of the galaxies is small (0.3 magnitudes). The BCGs exhibit very little luminosity evolution in this redshift range: if q0 = 0.0 we detect no luminosity evolution; for q0 = 0.5 we measure a small negative evolution (i.e., BCGs were about 0.5 magnitudes fainter at z = 1 than today). If the mass in stars of these galaxies had remained constant over this period of time, substantial positive luminosity evolution would be expected: BCGs should have been brighter in the past since their stars were younger. A likely explanation for the observed zero or negative evolution is that the stellar mass of the BCGs has been assembled over time through merging and accretion, as expected in hierarchical models of galaxy formation. The colour evolution of the BCGs is consistent with that of an old stellar population (zform > 2) that is evolving passively. We can thus use evolutionary population synthesis models to estimate the rate of growth in stellar mass for these systems. We find that the stellar mass in a typical BCG has grown by a factor ≃ 2 since z ≃ 1 if q0 = 0.0 or by factor ≃ 4 if q0 = 0.5. These results are in remarkably good agreement with the predictions of semi-analytic models of galaxy formation and evolution set in the context of a hierarchical scenario for structure formation.

scholarly journals The Hubble diagram for red magnitudes of bright cluster galaxies

1977 ◽  
Vol 37 ◽  
pp. 309-311 ◽  
Author(s):  
J. Kristian ◽  
A. R. Sandage ◽  
J. A. Westphal
Keyword(s):  
Hubble Diagram ◽  
Cluster Galaxies

Nous présentons le diagramme de Hubble des amas brillants de galaxies.

scholarly journals The Status of the Hubble Diagram In 1986

1987 ◽  
Vol 124 ◽  
pp. 129-141 ◽  
Author(s):  
Hyron Spinrad ◽  
S. Djorgovski
Keyword(s):  
Near Infrared ◽  
Radio Galaxies ◽  
Current Data ◽  
High Flux ◽  
Hubble Diagram ◽  
Active Star ◽  
Cluster Galaxies ◽  
Near Ir ◽  
Evolutionary Changes ◽  
The Status

We present visual and near-infrared Hubble diagrams for first-ranked cluster galaxies, and moderate-flux and high-flux radio galaxies. The photometric improvements and the extension of the diagrams to large redshifts (up to z ≃ 1.8) for both 3CR and “1 Jy” class radio galaxies are highlighted. The absolute luminosities of these three types of “standard candles”, where their redshifts overlap, agree adequately. The near-IR (2μm) Hubble diagrams may be used to determine the global deceleration parameter, q0, and the current data favor q0 ∼ +0.2 to +0.3. The sensitivity to evolutionary changes in the giant galaxies is quite modest at these long wavelengths. On the other hand, the visual regime (BV R) shows a dramatic dependence on differential evolution effects, which dominate over the cosmological model differences. Most radio galaxies apparently have had active star formation, with a continually declining rate, but a few are quite faint and red; they may have had a relatively passive evolution.

Sign in / Sign up

Export Citation Format

Share Document