RT info:eu-repo/semantics/bachelorThesis
T1 Estimación del desplazamiento al rojo para las galaxias en el Southern H-ATLAS Regions Ks-band Survey
A1 González Álvarez, David
K1 Redshift fotométrico
K1 SHARKS
K1 Banda Ks
AB This project focuses on obtaining the photometric redshift (photo-z) for galaxies in the first data release (DR1) of the Southern H-ATLAS Regions Ks BandSurvey (SHARKS). In particular, we will study the effect of incorporating theKs-band in the photo-z estimates.A limiting factor in obtaining the redshift by photometric means is the lackof spectral coverage, especially when the SHARKS data are only in the Ks-band.Because of this, we will make use of an astronomical catalog that covers the sameregion of the sky in the optical range, the Dark Energy Survey (DES), in particular DES-DR2.Before proceeding to the photo-z calculation, we study the calibration of theSHARKS-DR1 data. For this purpose, we will proceed with a near-infrared astronomical catalog that will act as a reference, 2MASS. In this section of theproject, using a linear regression between the magnitudes of both catalogs, wewill measure the calibration difference between them. In this case, we expect onlyto measure the difference between the calibration in the Vega and AB system.As for the photometric redshift, it is noteworthy that since this is the firsttime that these are calculated with SHARKS data, we have focused on a subsample where we have selected only galaxies with a distinct SHARKS-DES detection.For the selection of galaxies, we will use color-color space separation that occurs when using infrared bands. The calculation of the photometric redshift hasbeen performed using the Lephare software. Before the execution, we must definethe library of galaxy model templates that we will use (SEDs, Spectral EnergyDistribution), here we will use a library of 8 templates. For their subsequent convolution, we will also introduce the filters with which we took the measurements,i.e. those of the DECam and VIRCAM cameras. Then, we proceed to calculatethe magnitudes as a function of the redshift for the templates, and finally, weperform a minimization of the reshift for the templates. Finally, a minimizationby the 2 fitting method is carried out to obtain the redshift and the template thatbest fits the observed galaxy.To validate the results, we calculate statistical metrics of the bias and dispersion of the photo-z, concerning a small calibration sample with spectroscopicredshift, limited to low redshift. Next, we compare the overall redshift distributions obtained with and without using the Ks-band and look at some examplesof outliers.In general, we find that using SHARKS Ks-band improves the photo-z estimates, compared to the similar estimates using only DES data, through a decreasein the number of catastrophic results (outliers).
YR 2021
FD 2021
LK http://riull.ull.es/xmlui/handle/915/25011
UL http://riull.ull.es/xmlui/handle/915/25011
LA es
DS Repositorio institucional de la Universidad de La Laguna
RD 06-ago-2024