Mathematics – Probability
Scientific paper
Jan 1995
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995stin...9727602m&link_type=abstract
Technical Report, OUAST/95/32 Nuclear and Astrophysics Lab.
Mathematics
Probability
Galaxies, Error Analysis, Angular Correlation, Cosmology, Systematic Errors, Astronomical Catalogs, Statistical Analysis, Surveys, Scale Models, Root-Mean-Square Errors, Red Shift, Probability Theory, Photometry, Magnitude, Extraterrestrial Matter
Scientific paper
We present measurements of the angular two-point galaxy correlation function, omega(theta), from the APM Galaxy Survey. The performance of various estimators of omega(theta) is assessed by analyzing simulated galaxy catalogues. We use these tests, and analytic arguments, to select estimators which are least affected by large-scale gradients in the galaxy counts correlated with the survey boundaries. An error analysis of the plate matching procedure in the APM Galaxy Survey shows that residual plate-to-plate errors do not bias our estimates of omega(theta) by more than approx. 1 x 10-3. A direct comparison between our photometry and external CCD photometry of over 13,000 galaxies from the Las Campanas Deep Redshift Survey shows that the rms error in the APM plate zero points lies in the range 0.04-0.05 magnitudes, in agreement with our previous estimates. The comparison with the CCD photometry sets tight limits on any variation of the magnitude scale with right ascension. We find no evidence for any systematic errors in the survey correlated with the date of scanning and exposure. We estimate the effects on omega(theta) of atmospheric extinction and obscuration by dust in our Galaxy and conclude that these are negligible. There is no evidence for any correlations between the errors in the survey and limiting magnitude except at the faintest magnitudes of the survey, bj greater than 20, where star-galaxy classification begins to break down introducing plate-to-plate variations in the completeness of the survey. We use our best estimates of the systematic errors in the survey to calculate corrected estimates of omega(theta). Deep redshift surveys are used to determine the selection function of the APM Galaxy Survey, i.e. the probability that a galaxy at redshift z is included in the sample at a given magnitude limit. The selection function is applied in Limber's equation to compute how omega(theta) scales as a function of limiting magnitude. Our estimates of omega(theta) are in excellent agreement with the scaling relation, providing further evidence that systematic errors in the APM survey are small. We explicitly remove large-scale structure by applying filters to the APM galaxy maps and conclude that there is still strong evidence for more clustering at large scales than predicted by the standard scale-invariant Cold Dark Matter (CDM) model. We compare the APM omega(theta) and the three dimensional power spectrum derived by inverting omega(theta), with the predictions of scale-invariant CDM models. We show that the observations require Gamma = Omega0h in the range 0.2-0.3 and are incompatible with the value Omega = 0.5 of the standard CDM model.
Efstathiou George
Maddox Steve J.
Sutherland Will J.
No associations
LandOfFree
The APM Galaxy Survey III: an Analysis of Systematic Errors in the Angular Correlation Function and Cosmological Implications does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The APM Galaxy Survey III: an Analysis of Systematic Errors in the Angular Correlation Function and Cosmological Implications, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The APM Galaxy Survey III: an Analysis of Systematic Errors in the Angular Correlation Function and Cosmological Implications will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-838466