New searches for HI 21-cm in damped Lyman-alpha absorption systems (2009)
Curran, S. J., Tzanavaris, P., Darling, J. K., Whiting, M. T., Athreya, R., ...
We present the results of three separate searches for HI 21-cm absorption in a total of twelve damped Lyman-alpha absorption systems (DLAs) and sub-DLAs over the redshift range z = 0.86-3.37. We find...
Normal galaxies in the XMM-Newton fields. X-rays as a star formation indicator (2009)
Rovilos, E., Georgantopoulos, I., Tzanavaris, P., Pracy, M., Whiting, M., Woods, D., ...
Context: We use the first XMM serendipitous source catalogue (1XMM) to compile a sample of normal X-ray galaxies Aims: We seek to expand the database of X-ray selected normal galaxies at intermediate...
Normal galaxies in the XMM-Newton fields - X-rays as a star formation indicator (2009)
Rovilos, E., Georgantopoulos, I., Tzanavaris, P., Pracy, M., Whiting, M., Woods, D., ...
The galaxy luminosity function and its evolution with Chandra (2008)
Tzanavaris, P., Georgantopoulos, I.
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 207 normal galaxies...
The X-ray luminosity function of galaxies and its evolution (2008)
Georgantopoulos, I., Tzanavaris, P.
We compile one of the largest ever samples to probe the X-ray normal galaxy luminosity function and its evolution with cosmic time. In particular, we select 207 galaxies (106 late and 101 early-type...
Curran, S. J., Tzanavaris, P., Pihlstroem, Y. M., Webb, J. K.
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. We add our...
Detection of broad 21-cm absorption at z = 0.656 in the complex sight-line towards 3C336 (2007)
Curran, S. J., Tzanavaris, P., Murphy, M. T., Webb, J. K., Pihlstroem, Y. M.
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 integrated optical depth...
Murphy, M. T., Tzanavaris, P., Webb, J. K., Lovis, C.
Echelle spectrographs currently provide some of the most precise and detailed spectra in astronomy, the interpretation of which sometimes depends on the wavelength calibration accuracy. In some...
Searching for hidden AGN in nearby star-forming galaxies with Chandra (2007)
Tzanavaris, P., Georgantopoulos, I.
(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-massive black...
Tzanavaris, P., Murphy, M. T., Webb, J. K., Flambaum, V. V., Curran, S. J.
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 g-factor and...
X-ray number counts of normal galaxies (2006)
Georgakakis, A., Georgantopoulos, I., Akylas, A., Zezas, A., Tzanavaris, P.
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 differential X-ray...
Searching for X-ray luminous 'normal' galaxies in 2dfGRS (2006)
Tzanavaris, P., Georgantopoulos, I., Georgakakis, A.
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 most X-ray...
Tzanavaris, P., Webb, J. K., Murphy, M. T., Flambaum, V. V., Curran, S. J.
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 factor, and...
Constraints on reionization from the thermal history of the intergalactic medium. (2002)
Theuns, T., Schaye, J., Zaroubi, S., Kim, T-S., Tzanavaris, P., Carswell, B.
The temperature of the diffuse, photoheated intergalactic medium (IGM) depends on its reionization history because the thermal timescales are long. The widths of the hydrogen Lya absorption lines...
Constraints on reionization from the thermal history of the intergalactic medium (2002)
Theuns, T., Schaye, J., Zaroubi, S., Kim, T. S., Tzanavaris, P., Carswell, B.
The temperature of the diffuse, photoheated intergalactic medium (IGM) depends on its reionization history because the thermal timescales are long. The widths of the hydrogen Lyalpha absorption lines...
Temperature fluctuations in the intergalactic medium (2002)
Theuns, T., Zaroubi, S., Kim, T. S., Tzanavaris, P., Carswell, R. F.
The temperature of the low-density intergalactic medium (IGM) is set by the balance between adiabatic cooling resulting from the expansion of the Universe, and photoheating by the ultraviolet (UV)...