arXiv subjects

Adam Trapp

Publications and source records attributed to Adam Trapp.

2 recordsLinked to original sources

arXiv2021

Constraints on the End of Reionization from the Density Fields Surrounding Two Highly Opaque Quasar Sightlines

The observed large-scale scatter in Lyman $\alpha$ opacity of the intergalactic medium at $z<6$ implies large fluctuations in the neutral hydrogen fraction that are unexpected long after reionization has ended. A number of models have emerged to explain these fluctuations that make testable predictions for the relationship between Ly$\alpha$ opacity and density. We present selections of $z=5.7$ Ly$\alpha$-emitting galaxies (LAEs) in the fields surrounding two highly opaque quasar sightlines with long Ly$\alpha$ troughs. The fields lie towards the $z=6.0$ quasar ULAS J0148+0600, for which we re-analyze previously published results using improved photometric selection, and towards the $z=6.15$ quasar SDSS J1250+3130, for which results are presented here for the first time. In both fields, we report a deficit of LAEs within 20 $h^{-1}$ Mpc of the quasar. The association of highly opaque sightlines with galaxy underdensities in these two fields is consistent with models in which the scatter in Ly$\alpha$ opacity is driven by large-scale fluctuations in the ionizing UV background, or by an ultra-late reionization that has not yet concluded at $z=5.7$.

astro-ph.CO↗

arXiv2019

From BRAVA to BAaDE: A New Kinematic Survey of the Bulge AGB

We consider interesting results on the kinematics of the bulge, beginning with Mould's (1983) measurement of the velocity dispersion of the late M giants in the bulge, and carrying the discussion on to the present day, to discuss the largest survey ever undertaken of luminous SiO maser AGB stars. This SiO maser population of AGB stars is too luminous to have evolved from the oldest globular cluster age stellar population, yet has a velocity dispersion consistent with the oldest populations (the red clump stars) in the bulge. We identify two groups of maser stars by their kinematics; the subgroup with kinematics similar to the bulge has the highest bolometric luminosities with some giants reaching $M_{bol}<-6$. In a new result, we find that the most luminous maser stars with bulge kinematics are concentrated to the Galactic plane with the most luminous maers being found at $b<\mid 1.5^\circ \mid$; while the disk maser population shows no such difference. This mirrors a similar concentration to the Galactic Center found for long period Miras, noted in earlier studies. We conclude that the maser population represents another facet of the growing tension between evidence supporting a bulge population dominated by old stars, and a significant fraction of intermediate age stars.

astro-ph.GA↗