The disk of the Milky Way beyond the solar circle is not open to simple

interpretations. In short, it is a mess. From observations of interstellar

gas it is clear that the disk has both a warp and a flare.

The stellar component is riddled with stellar over-densities and/or streams,

the largest of which is the Monoceros stream. It is unclear whether gas

is in-falling and still building the outer disk, whether the distribution

of dark matter inflates the outer disk, if interactions with satellite

galaxies are perturbing the disk or if disrupted satellites are adding

to the disk. It is possible that all of these effects are contributing.

What is clear is that the outer disk of the Galaxy holds many clues as to

how galaxies form and evolve.



   Studying stellar populations in the outer disk is useful but currently has

limitations because spatial and kinematic distributions are not uniquely

described by the various Galactic models. I will discuss our current

attempts at helping to constrain properties of the outer disk using

spectroscopic analysis of A-star samples. Most of the talk will be dedicated

to our analysis of chemically peculiar A-stars in the SDSS DR8 sample and

whether the distribution of these stars indicate that the Monoceros stream

contains ancient blue stragglers or younger A-stars. The latter conclusion

might suggest that the stream is a component of disk of the Galaxy, while the

former might indicate dwarf disruption. I will conclude the talk by showing

our current work on the Canis Major Over-density and our future goal to explore

dust distribution in the disk using A-stars

 

There is evidence at low redshift of an increase in the AGN fraction of galaxies in close pairs. This naturally suggests a possible relation between galaxy mergers or interactions and AGN activity, but there seems to be no excess of disturbed morphologies in AGN when compared with quiescent galaxies, even to z~2. To investigate this apparent discrepancy, I utilize HST/WFC3 Infrared Grism observations in the CANDELS GOODS-S and Ultra Deep Survey fields to create a NIR redshift catalog with the intent of calculating the fraction of X-Ray and IR selected AGN in close pairs out to z~2.

Super-massive black holes reside at the center of galaxies. And the masses of these black holes correlate to various properties of their host galaxies. These correlations are the foundation for theories of the (co-)evolution of super-massive black holes and their host galaxies.

However, very few galaxies are nearby enough for direct black hole mass measurements. To find suitable galaxies, we surveyed a thousand galaxies with the Hobby-Eberly Telescope. The first results of this survey was the discovery of a dozen extremely compact, high-dispersion, galaxies, which are candidates to host extraordinary massive black holes. The prototype is NGC1277, which is a small, Re=1kpc, compact, lenticular galaxy which hosts a 10 billion solar mass black hole. Which is a significant fraction of this galaxies mass. These highly compact galaxies appear to be the passively evolved descendants of the red nuggets, sub-mm galaxies, and quasars found at high redshifts.

The nature of cooling in galaxy cluster has been puzzling since cool
core clusters were first discovered. Even though early X-ray observations
suggested copious amount of cooling, optical observations failed to detect star
formation at the levels suggested by X-rays. More recently, dispersed
spectroscopy with Chandra and XMM-Newton has revealed a dearth of gas below
1/3 of the mean cluster temperature. Heating mechanisms have been invoked
to account for the temperature floor and residual star formation, but the
details remain unclear.
Probes for the hot X-ray (~10 MK), cool optical (~10,000 K), and
intermediate temperature (~100,000 -- 1 million K) phases are necessary to
unravel the balance between heating and cooling in clusters. Recently, coronal
line emission from gas of ~1 million K has been reported near NGC 4696, the
Brightest Cluster Galaxy in the Centaurus galaxy cluster. By contast, gas at 2
million K was not detected.
In this talk I build upon a new facility in Cloudy that allows for
time-dependent, non-advective simulations. I use this capability to follow
a parcel of gas as it cools from ~80 MK to ~10,000 K. I show that the lack
of 2 million K gas is not due to extinction. I use the observed upper limit
to place an upper limit to the temperature of the coronal gas, and find that, if
the gas is cooling, it is cooling isochorically. I discuss scenarios for the
origin of the coronal gas, and propose observational probes for gas at
temperatures between a million and 10,000 K, that could shed some light into
cooling processes in galaxy clusters.

We will have Robert Stokes talking about the early history of cosmic microwave background measurements. In the late 60s, Robert was a graduate student at Princeton working with David Wilkinson (the W in WMAP) on measuring the spectrum of CMB. He will have interesting stories to tell about the early days of CMB discovery.

 I will present Beyond The Peak: a FTS spectral mapping survey of ionized, neutral and molecular gas of 22 nearby SINGS galaxies. These observations spatially resolve line emission from [NII], [CI] and 12CO from J(4-3) to J(13-12). A key project goal is to develop diagnostics and an understanding of molecular excitation. This can impact the relation between ground based observations of 12CO and mass density, driving deviations from established empirical relations, like KS, by up to an order of magnitude in different environments. These data provide observational diagnostics of how CO excitation varies inside and between galaxies, and how to use ancillary data needed to correctly interpret low-J observations without mid-J and high-J 12CO transitions.

Surveys now show that a significant fraction (approximately one quarter) of early-type galaxies have molecular gas, detected via CO. The molecular gas in early-types is found to be in very central distributions, where the effects of shear, hydrostatic pressure and possible AGN influence will be maximal. But little is yet known about the state of molecular gas in these galaxies. I will present the results of a survey of 18 molecular-gas rich early-type galaxies from the Atlas3d sample in 12CO, 13CO, HCN and HCO+ from the IRAM 30m telescope. This study reveals a wide range of average optical depths for the molecular gas, but a fairly constant dense gas fraction. We also currently know little about the origin of the molecular gas in these systems, but the molecular gas kinematics indicate that accretion from external sources plays an important role. Additionally, I will discuss whether the molecular gas in early-type galaxies may be less efficient at forming stars, despite the universal molecular gas-SFR relation observed for other galaxy types.

Abstract: One of the best-motivated classes of dark-matter candidate is the Weakly-Interacting Massive Particle (WIMP). In this talk, I will discuss WIMPs in the context of direct-detection experiments. First, I will discuss a new signal for WIMP dark matter: gravitational focusing in direct-detection experiments. This effect leads to an energy-dependent phase-shift in the peak direct-detection event rate throughout the year. I will discuss this in light of current putative annual-modulation claims. Second, I will discuss what we can learn about WIMPs in the "early-discovery" days once WIMPs are conclusively found in direct-detection experiments. I will show that what we can learn about WIMPs depends sensitively on the ensemble of experiments that are running at the time of discovery.