Evidence For Cosmological Evolution Research Articles

An absorption-line survey of 32 QSOs at red wavelengths - Properties of the MG II absorbers

The results of a survey of 32 QSOs for Mg II absorption at red wavelengths are presented, and the properties of the metal absorption systems are investigated. When interpreted in terms of ejection, the Mg II absorption systems are randomly distributed in velocity relative to the QSOs, although the systems may cluster on scales of a few thousand km/s. This is consistent with the absorption systems arising in intervening material not associated with the QSOs. The equivalent width distribution of the Mg II systems is well fitted by either an exponential or a power-law distribution, with the number density of the absorption systems increasing with decreasing rest equivalent width. There is marginally significant evidence for cosmological evolution of the number density of the Mg II absorbers, and no evidence for evolution of the Mg II equivalent width distribution with redshift. 42 references.

A high-resolution study of the absorption spectra of three QSOs - Evidence for cosmological evolution in the Lyman-alpha lines

view Abstract Citations (107) References (12) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A high-resolution study of the absorption spectra of three QSOs: evidence for cosmological evolution in the Lyman-alpha lines. Young, P. ; Sargent, W. L. W. ; Boksenberg, A. Abstract High-resolution (0.8 Å FWHM) spectroscopic observations over the wavelength range from 3260 Å to 4900 Å are presented for the QSOs Q0002+051 (Zem = 1.899), Q0421+019 (Zem = 2.051), and the gravitationally lensed QSO, Q1115+080 (Zem = 1.725). We find, respectively, 28, 53, and 21 absorption lines in these three objects, from which a total of 11 absorption line systems are identified. Two of the QSOs show galactic Ca II λλ3934, 3969 absorption. Four absorption systems with Zabs > Zem are seen in Q1115+080; the velocities range from -360 to -1130 km s-1 relative to the QSO. Line profile fits to the absorption spectra are used to determine column densities and velocity dispersions within the absorbing clouds. Highly ionized lines of C IV λλ1548, 1550, N V λλ1238, 1242, and Si IV λλ1393, 1402 are seen in many of the absorption systems. The many unidentified lines shortward of Ly emission are used to form an expanded sample of single Lyα absorption lines. The new data provide good statistics for Zabs < 2 and reveal a number density per unit redshift N(Z) = N0(1 + Z)γ with y = 1.81 ± 0.48. This suggests a modest amount of cosmological evolution in the sense that there are more Lyα absorption lines at higher redshifts. The properties of the equivalent width spectrum of Lyα lines and the flatness of their two-point correlation function are in accord with our previous study. Publication: The Astrophysical Journal Pub Date: January 1982 DOI: 10.1086/159529 Bibcode: 1982ApJ...252...10Y Keywords: Absorption Spectra; Astronomical Spectroscopy; Big Bang Cosmology; Galactic Evolution; Lyman Alpha Radiation; Quasars; High Resolution; Line Spectra; Red Shift; Ultraviolet Spectra; Velocity Distribution; Astrophysics full text sources ADS | data products NED (12) SIMBAD (7)

Cosmological Evolution in Radiogalaxies

The evidence for Cosmological evolution in radiogalaxies is now stronger, and the shortness of the time scale for this evolution (109 years) compared with the typical ages of galaxies poses a serious problem for the conventional view of galactic history.