arXiv subjects

Basel Mostafa

Publications and source records attributed to Basel Mostafa.

3 recordsLinked to original sources

arXiv2022

Implications of a Temperature Dependent IMF III: Mass Growth and Quiescence

The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, $T_{IMF}$ , into photometric template fitting, suggest most galaxies obey an IMF top-heavier than the Galactic IMF. The implications of these revised fits on mass functions, quiescence and turnoff are discussed. At all redshifts the highest mass galaxies become quiescent first with the turnoff mass decreasing towards the present. The synchronous turnoff mass across galaxies suggests quiescence is driven by universal mechanisms rather than by stochastic or environmental processes.

astro-ph.GA↗

arXiv2022

Implications of a Temperature Dependent IMF II: An Updated View of the Star-Forming Main Sequence

The stellar initial mass function (IMF) is predicted to depend upon the temperature of gas in star-forming molecular clouds. The introduction of an additional parameter, $T_{IMF}$ , into photometric template fitting, allows galaxies to be fit with a range of IMFs. Three surprising new features appear: (1) most star-forming galaxies are best fit with a bottom-lighter IMF than the Milky Way; (2) most star-forming galaxies at fixed redshift are fit with a very similar IMF; and (3) the most massive star-forming galaxies at fixed redshift instead exhibit a less bottom-light IMF, similar to that measured in quiescent galaxies. Additionally, since stellar masses and star formation rates both depend on the IMF, these results slightly modify the resulting relationship, while yielding similar qualitative characteristics to previous studies.

astro-ph.GA↗

arXiv2022

Implications of a Temperature Dependent IMF I: Photometric Template Fitting

A universal stellar initial mass function (IMF) should not be expected from theoretical models of star formation, but little conclusive observational evidence for a variable IMF has been uncovered. In this paper, a parameterization of the IMF is introduced into photometric template fitting of the COSMOS2015 catalog. The resulting best-fit templates suggest systematic variations in the IMF, with most galaxies exhibiting top-heavier stellar populations than in the Milky Way. At fixed redshift, only a small range of IMFs are found, with the typical IMF becoming progressively top-heavier with increasing redshift. Additionally, subpopulations of ULIRGs, quiescent- and star-forming galaxies are compared with predictions of stellar population feedback and show clear qualitative similarities to the evolution of dust temperatures.

astro-ph.GA↗