Calendar

Oct
8
Mon
Pizza lunch: Patrick Gaulme
Oct 8 @ 12:30 pm – 1:30 pm
Pizza lunch: Patrick Gaulme @ AY 119

Red giants, eclipsing binaries, and asteroseismology.

Patrick Gaulme, Max Planck Institute for Solar System Research

Jan
23
Wed
Colloquium Thesis Defense: Lauren Kahre
Jan 23 @ 3:00 pm – 4:00 pm
Colloquium Thesis Defense: Lauren Kahre

Extinction Mapping and Dust-to-Gas Ratios of Nearby Galaxies

Lauren Kahre, NMSU

We present a study of the dust{to{gas ratios in 31 nearby (D >
10 Mpc) galaxies. Using Hubble Space Telescope broad band WFC3/UVIS UV and
optical images from the Treasury program LEGUS (Legacy ExtraGalactic UV
Survey) combined with archival HST/ACS data, we correct thousands of
individual stars for extinction across these galaxies using an
isochrone-matching (reddening-free Q) method. We generate extinction maps
for each galaxy from the individual stellar extinctions using both
adaptive and fixed resolution techniques, and correlate these maps with
neutral HI and CO gas maps from literature, including The HI Nearby Galaxy
Survey (THINGS) and the HERA CO-Line ExtraGalactic Survey (HERACLES). We
calculate dust-to-gas ratios and investigate variations in the dust-to-gas
ratio with galaxy metallicity. We find a power law relationship between
dust-to-gas ratio and metallicity. The single power law is consistent with
other studies of dust-to-gas ratio compared to metallicity, while the
broken power law shows a significantly shallower slope for low metallicity
galaxies than previously observed. We find a change in the relation when
H_2 is not included. This implies that underestimation of N_H2 in
low-metallicity dwarfs from a too-low CO-to-H2 conversion factor X_CO
could have produced too low a slope in the derived relationship between
dust-to-gas ratio and metallicity. We also
compare our extinctions to those derived from fitting the spectral energy
distribution (SED) using the Bayesian Extinction and Stellar Tool (BEAST)
for NGC 7793 and and systematically lower extinctions from SED-fitting as
compared to isochrone matching. Finally, we compare our extinction maps of
NGC 628 to maps of the dust obtained via IR emission from Aniano et al.
(2012) and find a factor of 2 difference in dust-to-gas ratios determined
from the two maps, consistent with previous work.

Jan
25
Fri
Pizza Lunch Talk: Dale Frail
Jan 25 @ 11:30 am – 12:30 pm
Pizza Lunch Talk: Dale Frail @ AY 119

How to Write A Competitive Prize Postdoc Application

Dale Frail, NRAO

Feb
22
Fri
Pizza Lunch Talk: Takashi Sekii
Feb 22 @ 12:15 pm – 1:15 pm
Pizza Lunch Talk: Takashi Sekii @ AY 119

Title

Takashi Sekii, National Astronomical Observatory of Japan

Abstract

Mar
4
Mon
Pizza Lunch Talk: Mark Rutkowski
Mar 4 @ 12:30 pm – 1:30 pm
Pizza Lunch Talk: Mark Rutkowski @ AY 119

Ultraviolet Observations of Galaxies

Mark Rutkowski, Minnesota State Univeristy

Ultraviolet observations are essential for answering fundamental questions regarding the role and impact of galaxies in universe. I’ll discuss a number of past, ongoing, and future UV-optical-near IR high redshift surveys with which I am involved and the specific constraints the UV provides on these open questions. Specifically, I’ll highlight the utility of UV observations of starbursts and quiescent galaxies alike for constraining the history of reionization, hierarchical assembly, and (if there’s time) the cosmic history of metals.

Apr
22
Mon
Pizza lunch: Sarah Kovac/David DeColibus
Apr 22 @ 12:30 pm – 1:30 pm
Pizza lunch: Sarah Kovac/David DeColibus @ AY 119

ASTR 598

Apr
29
Mon
Pizza lunch: Kristen Luchsinger
Apr 29 @ 12:30 pm – 1:30 pm
Pizza lunch: Kristen Luchsinger @ AY 119

ASTR 598

Aug
20
Tue
Pizza lunch: Nick Arge
Aug 20 @ 12:00 pm – 1:00 pm
Pizza lunch: Nick Arge @ AY 119

Title

Nick Arge, NASA Goddard Space Flight Center

Aug
23
Fri
Colloquium: Safe Zone Training (Host: Inclusive Astronomy Group)
Aug 23 @ 3:15 pm – 4:15 pm
Colloquium: Safe Zone Training (Host: Inclusive Astronomy Group) @ BX102

Safe Zone Training

Dr. Zooey Sophia Pook, NMSU

The SafeZone Training was established to educate and train students, faculty, and staff on how to provide safe and affirming support to members of the gay, lesbian, bisexual, transgender, and questioning community.

Sep
12
Thu
Colloquium Thesis Proposal: Rachel Marra
Sep 12 @ 1:30 pm – 2:30 pm
Colloquium Thesis Proposal: Rachel Marra @ Jett Hall 210

An Observer’s Examination of the Circumgalactic Medium using Cosmological Simulations

Rachel Marra, NMSU

A significant aspect to understanding galaxy evolution is having an understanding of the intricacies involving the inflow and outflow of baryons onto a galaxy. Gas needs to accrete onto the galaxy in order for star formation to occur, while stellar winds, supernovae, and radiation pressure result in the outflow of gas from the galaxy. The diffuse region around the galaxy that has gas from interstellar medium (ISM) inflows and intergalactic medium (IGM) outflows interacting is the circumgalactic medium (CGM). Studying the CGM will help us learn about the baryon cycle and give us a better understanding of galactic evolution.

The primary method to studying the CGM is through absorption, as the density is too low to detect emission. Studying these absorption features allows us to learn about the physical properties of the gas giving rise to the absorption. Other than through observations, cosmological simulations play a large role in how we learn about the CGM of galaxies. Using MOCKSPEC, the Quasar Absorption Line Analysis Pipeline, to create mock quasar sightlines through the VELA simulation suite of galaxies, we use the absorption features seen in the sightlines to study the CGM in the simulations. While there are many ions that are used to study the CGM, we focus on OVI.

We intend to study how effective our methods are for studying the CGM with both observations and simulations. The covering fraction of OVI for a sample of observed galaxies will be compared with the covering fraction that is found from a selection of LOS that probe simulated, Milky-Way type galaxies. This tells us if the simulations can reproduce the observations, and if they do not, we can gain insights as to why the simulations do not match observed data. We will also investigate if the metallicity calculated from an observed absorption feature reflects the actual metallicity of the probed gas by using mock sightlines through simulations. Additionally, we will do a comparison of different methodologies used to study the CGM in simulations, to determine if using mock quasar sightlines is a more realistic and accurate method to compare to observed data.