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Jan 20
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No talk scheduled.
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Jan 27 |
John Kormendy
University of Texas at Austin |
"Scaling Laws for Dark Matter Halos in Late-Type and Dwarf Spheroidal Galaxies"
Dark matter (DM) halos of Sc-Im and dwarf spheroidal (dSph) galaxies satisfy
scaling laws: halos in lower-luminosity galaxies have smaller core radii,
higher central densities, and smaller velocity dispersions. These results are
based on maximum-disk rotation curve decompositions for giant galaxies and
Jeans equation analysis for dwarfs.
(1) We show that spiral, lm, and Sph galaxies with absolute magnitudes M_V > -18
form a sequence of decreasing baryon-to-DM surface density with decreasing
luminosity. We suggest that this is a sequence of decreasing baryon retention
versus supernova-driven losses or decreasing baryon capture after cosmological
reionization.
(2) The structural differences between S+lm and Sph galaxies are small. Both are
affected mostly by the physics that controls baryon depletion.
(3) There is a linear correlation between the maximum rotation velocities of
baryonic disks and the outer circular velocities Vcirc of test particles
in their DM halos. Baryons become unimportant at Vcirc = 42 + or - 4 km/s.
Smaller galaxies are dim or dark.
(4) We find that, absent baryon depletion and with all baryons converted into
stars, dSph galaxies would be brighter by ~4.6 mag and dIm galaxies would be
brighter by ~3.5 mag. Both have DM halos that are massive enough to help
to solve the "too big to fail" problem with DM galaxy formation.
(5) We suggest that there exist many galaxies that are too dark to be discovered
by current techniques, as required by cold DM theory.
(6) Central surface densities of DM halos are constant from M_B ~ -5 to -22.
This implies a Faber-Jackson law with halo mass M alpha (halo dispersion)**4.
close
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Feb 3 |
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No talk scheduled.
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Feb 10 |
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No talk scheduled.
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Feb 17 |
John Lacy, Steve and Keely Finkelstein, and Harriet Dinerstein (4 speakers)
University of Texas at Austin |
"Sharing Teaching Techniques and Tools"
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Feb 24 |
Martha Boyer
NASA Goddard (host: Kristen McQuinn) |
"The Key Influence of AGB Stars on the Evolution and Global Properties of Galaxies"
abstract
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Mar 2 |
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No talk scheduled.
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Mar 9 |
Amanda Kepley
National Radio Astronomy Observatory (NRAO) |
"Opening New Frontiers in the Study of Star Formation"
abstract
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Mar 16 |
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Spring Break: No talk scheduled.
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Mar 23 |
Joel Green
Space Telescope Science Institute (STScI) (host: Yao-Lun Yang) |
"Extreme Accretion: The Evolution of the FU Orionis Disk"
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Mar 30 |
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No talk scheduled
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Apr 6 |
Eric Becklin
University of California, Los Angeles (hosts: John Lacy, Dan Jaffe) |
"Stratospheric Observatory for Infrared Astronomy (SOFIA): Overview, the First Science Results, and Future Opportunities"
abstract
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Apr 13 |
Brendan Bowler
University of Texas at Austin (Hubble Fellow) |
"The Architecture, Atmospheres, and Origin of Giant Planets with High-Contrast Imaging"
abstract
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Apr 20 |
Anshu Gupta
Australian National University (host: Chao-Ling Hung) |
"Radial Distribution of Gas-Phase Metallicities of Galaxies in two CLASH Clusters at z ~ 0.35"
abstract
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Apr 27 |
Postdoc Mentoring Commitee
University of Texas at Austin |
"Applying for Your Next Job"
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May 4 |
Linda Strubbe
University of British Columbia (host: Jeff Silverman) |
"Developing scientific reasoning: at UBC and in West Africa"
abstract
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