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The Tully-Fisher relation in nearby clustersYoung, Paul January 1996 (has links)
In this thesis are presented the Tully-Fisher (TF) relations for a sample of 99 galaxies within the four nearby dusters; Coma, Abell 2199. Abell 2634 and Abell 194. Each cluster was compromised of two samples. The first sample was drawn from either Zwicky or UGC catalogues based on a combination of magnitude, type and ellipticity. These provided spiral duster member candidates over the entire duster region to a magnitude limit of 16 in the b-band. The second sample was selected from published photographic plate scans of the central areas of each duster. This sample had a fainter magnitude limit of 18 b-band mags but covered a much smaller area (approx. 2ºx2º). The galaxies were observed over two observing runs in May and August of 1993 on the JKT and INT Isaac Newton Group Telescopes simultaneously. I-band CCD images and optical long-slit spectra were taken of 65% of the sdected objects. Isophotal ellipse fitting of the images was used to produce surface brightness profiles. From these, isophotal magnitudes and diameters woe extracted. From, consideration of the surface brightness, ellipticity and position angle a "disk region" of each profile was selected and used to calculate extrapolated total magnitudes. Gaussian fitting of Ha emission lines of the long-split spectra produced optical rotation curves for each galaxy. Maximum rotation velocities were calculated from these curves. Corrections found in the literature were applied to the total magnitude and rotation velocity of each galaxy. These compensated for internal dust extinction and the inclination of the disk to the line-of sight. Numerical simulations of the fitting procedures demonstrated that an inverse regression of log-rotation velocity on magnitude provided a fit tothe relationship free from selection bias. Residuals around this fit woe used to choose forms of the corrections that produced the minimum scatter. A fullerror budget was compiled and an error weighted fit to the data yielded relationships with a mean scatter of 0.35 mags rms. A combination of all sources of measurement error, considering inter-correlation, produced a value of 027 mags rms, as an estimate of the contribution to the scatter. It was shown that uncertain cluster membership was not a significant source of scatter. In addition, the "expanding duster" model correction suggested in the literature did not significantly reduce the scatter. The most important source of scatter in the relationship was found to be the symmetry and extent of rotation curves used. A significant correlation was shown to exist between rotation curve extent in terms of disk scale lengths and the TF fit residuals. When only the highest quality data were used, the typical scatter was reduced to 020 mags rms. Consideration of the remaining measurement errors produced an upper limit of 0.12 mags rms for the intrinsic scatter within the TF relation. Monte-Carlo modelling indicated that the observed difference in TF slope between the Coma and Abell 2634 samples was significant, The possibility that this difference is the result of systematic errors in the dataset was ruled out It is concluded that the change in gradients is due to real variations in the underlying slope influenced by differences in duster environment.
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Redshifts photométriques et paramètres physiques des galaxies dans les sondages à grande échelle : contraintes sur l'évolution des galaxies massives / Photometric redshifts and physical parameters of galaxies in large scale surveys : constraints on galaxy evolutionMoutard, Thibaud 21 December 2015 (has links)
Cette thèse présente la mesure des redshifts photométriques et des paramètres physiques dans le cadre des sondages de galaxies à grande échelle, ainsi que la contrainte qui peut en être extraite sur l'évolution des galaxies. Je montre notamment dans cette thèse dans quelle mesure la calibration photométrique affecte la précision des redshifts photométriques, afin de contraindre la stratégie photométrique à développer pour la mission Euclid.Afin de prendre en compte les problèmes inhérents à l'observation, les analyses ont été effectuée sur la base de données observées dont la configuration est proche de celle qui est attendue pour Euclid. Ces données combinent de nouvelles observations en proche-infrarouges conduites pour couvrir le sondage spectroscopique VIPERS et la photométrie du CFHTLS. Sur la base des conclusions tirées de cette analyse, j'ai produit le nouveau catalogue photométrique de VIPERS, ainsi que le catalogue de redshifts photométriques associé. J'ai finalement utilisée la même photométrie pour dériver les paramètres physiques d'environ 760 000 galaxies, réparties sur plus de 22 degrés carrés à une magnitude limite Ks(AB) < 22. J'ai ainsi pu étudier l'évolution de la fonction de masse stellaire entre les redshifts z = 0.2 et z = 1.5. Ceci a permis de montrer que les galaxies dont la masse stellaire est d'environ log(M/Msol) = 10.66 voient généralement leur formation stellaire stoppée en 2 à 4 milliards d'années, alors que les galaxies de faible masse (log(M/Msol) < 9.5) ne formant plus d'étoiles ont vu leur formation stellaire être arrêtée 5 à 10 fois plus rapidement (en environ 0.4 milliard d'années). / This thesis presents the measurement of the photometric redshifts and physical parameters in the framework of large scale surveys, and their constraint on galaxy evolution. The photometric redshift measurement allows us to study the entire photometric sample. For this reason, the weak lensing signal measurement used in the Euclid mission as a primary cosmological probe will rely on photometric redshift measurements. However, the method is strongly affected by the quality of the photometry. In particular, I show in this thesis how the photometric calibration impacts the photometric redshift precison, in order to constrain the photometric strategy to use in the Euclid mission.Aiming to take into account for observationnal problems, the analysis is done with observationnal data whose photometric configuration is close to the expected Euclid one. These data combine new near-infrared observations conduected to cover the VIPERS spectroscopic survey and the CFHTLS photometry.Using the conclusions of this analysis, I have producted the new photometric catalogue for VIPERS and the associated photometric redshift calalogue.Finally, I used the same photometry to compute the stellar masses of 760,000 galaxies covering 22 square degrees at the limiting magnitude Ks(AB) < 22. This enabled me to study the evolution of the stellar mass function between redshifts z= 0.2 and z = 1.5. We have then shown that the star formation of galaxies with stellar masses around log(M/Msol) = 10.66 is stopped in 2-4 Gyr, while in quiescent low-mass (log(M/Msol) < 9.5) galaxies, the star formation has been stopped 5-10 times faster (approximatelly in 0.4 Gyr).
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