Calendar

Mar
31
Thu
Inclusive Astronomy Group
Mar 31 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
Apr
7
Thu
Inclusive Astronomy Group
Apr 7 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
Apr
14
Thu
Inclusive Astronomy Group
Apr 14 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
Apr
21
Thu
Inclusive Astronomy Group
Apr 21 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
Apr
28
Thu
Inclusive Astronomy Group
Apr 28 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
May
5
Thu
Inclusive Astronomy Group
May 5 @ 10:30 am – 11:30 am

We will explore ways to make astronomy, and STEM fields in general, a more inclusive and welcoming environment where EVERYONE can feel comfortable. This will make all people, including traditionally underrepresented groups, feel comfortable and welcomed working in our field.

One of the main goals this semester will be to identify and implement ways in which our own department can easily become more inclusive and welcoming. Come join us to find out what you can do!
Visit our webpage for more information about what we have been doing.
Feb
17
Fri
Colloquium: Michael Boylan-Kolchin
Feb 17 @ 3:15 pm – 4:15 pm
Colloquium: Michael Boylan-Kolchin @ BX 102

Near-field Cosmology: Big Science from Small Galaxies

Dr. M. Boylan-Kolchin, UT Austin

The local Universe provides a unique and powerful way to explore galaxy formation and cosmological physics. Through measurements of the abundances, kinematics, and chemical composition of nearby systems that can be studied in exquisite detail, we can learn about the initial spectrum of cosmological density fluctuations, galaxy formation, dark matter physics, and processes at cosmic dawn that might otherwise remain unobservable. I will summarize some of the new and surprising results in this rapidly-changing subject of “near-field cosmology” and discuss how these results are driving advances in both astronomy and particle physics.

Feb
20
Mon
Pizza Lunch: Stephanie Ho
Feb 20 @ 12:30 pm – 1:30 pm
Pizza Lunch: Stephanie Ho @ AY 119

Quasars Probing Galaxies: Signatures of Gas Accretion at z~0.2

Stephanie Ho, Univ. California Santa Barbara

 

Mar
2
Thu
Colloquium: Jack Burns (Host: Nancy Chanover)
Mar 2 @ 3:15 pm – 4:15 pm
Colloquium: Jack Burns (Host: Nancy Chanover) @ Domenici Hall Room 106

Cosmology from the Moon: The Dark Ages Radio Explorer (DARE)

Dr. Jack Burns, University of Colorado Boulder

In the New Worlds, New Horizons in Astronomy & Astrophysics Decadal Survey, Cosmic Dawn was singled out as one of the top astrophysics priorities for this decade. Specifically, the Decadal report asked “when and how did the first galaxies form out of cold clumps of hydrogen gas and start to shine—when was our cosmic dawn?” It proposed “astronomers must now search the sky for these infant galaxies and find out how they behaved and interacted with their surroundings.” This is the science objective of DARE – to search for the first stars, galaxies, and black holes via their impact on the intergalactic medium (IGM) as measured by the highly redshifted 21-cm hyperfine transition of neutral hydrogen (HI). DARE will probe redshifts of 11-35 (Dark Ages to Cosmic Dawn) with observed HI frequencies of 40-120 MHz. DARE will observe expected spectral features in the global signal of HI that correspond to stellar ignition (Lyman-α from the first stars coupling with the HI hyperfine transition), X-ray heating/ionization of the IGM from the first accreting black holes, and the beginning of reionization (signal dominated by IGM ionization fraction). These observations will complement those expected from JWST, ALMA, and HERA. We propose to observe these spectral features with a broad-beam dipole antenna along with a wide-band receiver and digital spectrometer. We will place DARE in lunar orbit and take data only above the farside, a location known to be free of human-generated RFI and with a negligible ionosphere. In this talk, I will present the mission concept including initial results from an engineering prototypes which are designed to perform end-to-end validation of the instrument and our calibration techniques. I will also describe our signal extraction tool, using a Markov Chain Monte Carlo technique, which measures the parameterized spectral features in the presence of substantial Galactic and solar system foregrounds.

 

Mar
31
Fri
Colloquium PhD Defense: Sean Markert
Mar 31 @ 3:15 pm – 4:15 pm
Colloquium PhD Defense: Sean Markert

THE SIGNAL OF WEAK GRAVITATIONAL LENSING FROM GALAXY
GROUPS AND CLUSTERS,

Dr. S. Markert, NMSU

 

The weak gravitational lensing of galaxy clusters is a valuable tool. The deflection of light around a lens is solely dependent on the underlying distribution of foreground mass, and independent of tracers of mass such as the mass to light ratio and kinematics. As a direct probe of mass, weak lensing serves as an independent calibration of mass-observable relationships. These massive clusters are objects of great interest to astronomers, as their abundance is dependent on the conditions of the early universe, and accurate counts of clusters serve as a test of cosmological model. Upcoming surveys, such as LSST and DES, promise to push the limit of observable weak lensing, detecting clusters and sources at higher redshift than has ever been detected before. This makes accurate counts of clusters of a given mass and redshift, and proper calibration of mass-observable relationships, vital to cosmological studies.
We used M> 10 13.5 h −1 M ⊙ halos from the MultiDark Planck simulation at z∼0.5 to study the behavior of the reduced shear in clusters. We generated 2D maps of convergence and shear the halos using the GLAMER lensing library. Using these maps, we simulated observations of randomly placed background sources, and generate azimuthal averages of the shear. This reduced shear profile, and the true reduced shear profile of the halo, is fit using analytical solutions for shear of the NFW, Einasto, and truncated NFW density profile. The masses of these density profiles are then compared to the total halo masses from the halo catalogs.
We find that fits to the reduced shear for halos extending past ≈ 2 h −1 Mpc are fits to the noise of large scale structure along the line of sight. This noise is largely in the 45 ◦ rotated component to the reduced tangential shear, and is a breakdown in the approximation of g tan ≈g tot required for density profile fitting of clusters. If fits are constrained to a projected radii of < 2 h −1 Mpc, we see massively improved fits insensitive to the amount of structure present along the line of sight.