279 citations · 1.7k across the 51 of their papers we have counts for
12 papers · 1 filter
The galaxy luminosity function and its evolution with Chandra
P. Tzanavaris, I. Georgantopoulos
AIMS: We have compiled one of the largest normal-galaxy samples ever to probe X-ray luminosity function evolution separately for early and late-type systems. METHODS: We selected 2…
Relationships between the HI 21-cm line strength, MgII equivalent width and metallicity in damped Lyman-alpha absorption systems
S. J. Curran, P. Tzanavaris, Y. M. Pihlstroem +1
We present the results of a survey for 21-cm absorption in four never previously searched damped Lyman-alpha absorption systems (DLAs) with the Westerbork Synthesis Radio Telescope…
Detection of broad 21-cm absorption at z = 0.656 in the complex sight-line towards 3C336
S. J. Curran, P. Tzanavaris, M. T. Murphy +2
We report the detection of 21-cm absorption at z = 0.656 towards 1622+238 (3C336). The line is very broad with a Full-Width Half Maximum (FWHM) of 235 km/s, giving a velocity integ…
Selection of ThAr lines for wavelength calibration of echelle spectra and implications for variations in the fine-structure constant
M. T. Murphy, P. Tzanavaris, J. K. Webb +1
Echelle spectrographs currently provide some of the most precise and detailed spectra in astronomy, the interpretation of which sometimes depends on the wavelength calibration accu…
Searching for hidden AGN in nearby star-forming galaxies with Chandra
P. Tzanavaris, I. Georgantopoulos
(ABRIDGED) AIMS: We searched for X-ray signatures of AGN in a sample of star-forming, relatively early-type, nearby spiral galaxies. Such galaxies are likely to host nuclear super-…
Probing variations in fundamental constants with radio and optical quasar absorption-line observations
P. Tzanavaris, M. T. Murphy, J. K. Webb +2
Nine quasar absorption spectra at 21-cm and UV rest-wavelengths are used to estimate possible variations in x=alpha^2 g_p mu, (alpha is the fine structure constant, g_p the proton…
X-ray number counts of normal galaxies
A. Georgakakis, I. Georgantopoulos, A. Akylas +2
We use the number counts of X-ray selected normal galaxies to explore their evolution by combining the most recent wide-angle shallow and pencil-beam deep samples available. The di…
Searching for X-ray luminous 'normal' galaxies in 2dfGRS
P. Tzanavaris, I. Georgantopoulos, A. Georgakakis
We cross-correlated the Chandra XASSIST and XMM-Newton Serendipitous Source Catalogues with the 2 degree Field Galaxy Redshift Survey (2dfGRS) database. Our aim was to identify the…
Limits on variations in fundamental constants from 21-cm and ultraviolet quasar absorption lines
P. Tzanavaris, J. K. Webb, M. T. Murphy +2
Quasar absorption spectra at 21-cm and UV rest-wavelengths are used to estimate the time variation of x=alpha^2 g_p mu, where alpha is the fine structure constant, g_p the proton g…
Size estimates for intervening C IV absorbers from high resolution spectroscopy of APM 0827+5255
Panayiotis Tzanavaris, Robert F. Carswell
A new analysis of Keck/HIRES observations of the broad absorption line QSO APM 0827+5255 indicates that a number of intervening C IV absorbers give rise to absorption lines for whi…
Galactic winds in the intergalactic medium
Tom Theuns, Matteo Viel, Scott Kay +3
We have performed hydrodynamical simulations to investigate the effects of galactic winds on the high-redshift (z=3) universe. Strong winds suppress the formation of low-mass galax…
Temperature fluctuations in the intergalactic medium
Tom Theuns, Saleem Zaroubi, Tae-Sun Kim +2
The temperature of the low-density intergalactic medium is set by the balance between adiabatic cooling resulting from the expansion of the universe, and photo-heating by the UV-ba…