The properties of post-starburst galaxies from spectral fitting

Galaxies--Evolution;Astronomical spectroscopy;Starbursts

Taj Aldeen, Laith Talib Hadi ; Wild, Vivienne ; Wild, Vivienne

University:University of St Andrews

Department:Physics & Astronomy (School of)

关键词: Galaxies--Evolution;    Astronomical spectroscopy;    Starbursts;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/18583/LaithTajAldeenPhDThesis.pdf?sequence=2&isAllowed=y

来源: DR-NTU

【 摘 要 】

A bimodality has been seen in the morphology, colour and star-forming properties of galaxies.Throughout cosmic time, the number of galaxies that are quenched to join the red-sequencehas increased, unlike the number of star forming galaxies. Post-starburst galaxies (PSB) aresuspected to be a transition phase between these two stages.We tried to answer the questions of the mechanism for this transformation. The goal ofour work is to see whether or not all PSB in the nearby universe are being quenched to jointhe red-sequence and by which mechanism. We try to show if there is any difference betweenthe low and high redshift PSB with regard to the accumulated stellar mass in the last 1 and1.5 Gyr, the star formation history and the amount of dust within the galaxies. In this work wefit the observed galaxies with the new STARLIGHT code that can fit spectra with or withoutphotometric data with a library of synthetic models.First we investigate 189 PSB candidates in the low redshift Sloan Digital Sky Survey (SDSS)and 1877 comparison samples of star forming and passive galaxies. Depending on the mass,low or high, we found more than one pathway and mechanism that may transform the bluecloud to become red sequence type galaxies. Secondly we use Ultra Deep Survey (UDS) andthe spectroscopic follow-up of the UKIDSS Ultra-Deep Survey (UDSz) data for the PSB galaxiesat 0.9 ≤ z ≤ 1.2. From the fitting of 323 galaxies, we determine more constrained physicalproperties of UDSz high redshift galaxies, such as the star formation history, mass fractionthat formed at the time of the burst and the dust contents of the galaxies. We speculate that ahigher gas content in these galaxies could have led to the higher burst.