About the INPA Seminars

All seminars are on Fridays (unless otherwise noted) and start at 12:00 (noon) with a brief presentation of the weekly scientific news. Typically the talks end by 13:00. The seminars take place in Bldg. 50A, room 5132.

The committee members are:

The following Seminar schedule for the Institute for Nuclear and Particle Astrophysics is tentative. The seminar becomes final usually a few days before the Friday of the talk.

If you have questions, comments, or suggestions please contact Paris C. Gordon at 510-486-4903 pcgordon@lbl.gov

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Hillary Child – Nonlinear Structure Formation at Two Scales: from Bispectrum Baryon Acoustic Oscillations to Evolution of Halo Profiles

February 1 @ 12:00 pm - 1:00 pm

The “cosmic web” of dark matter halos forms via the collapse of post-inflation density fluctuations. While linear perturbation theory describes this process well at large scales and low densities, it fails at small scales and high densities. I explore two facets of nonlinear structure formation that constrain cosmology: at mildly nonlinear scales, measuring the baryon acoustic oscillation (BAO) distance scale in the bispectrum, and at deeply nonlinear scales, tracking the evolution of simulated dark matter halo profiles.
At mildly nonlinear scales, the BAO distance scale constrains the expansion history of the universe and dark energy. The BAO feature has been detected in both the three-point correlation function and the bispectrum, but challenges remain in fully exploiting three-point data. I present a strategy to select triangle configurations that maximize the amplitude of the BAO signal in the bispectrum. A relatively small set of bispectrum measurements can improve constraints on the BAO length scale over power spectrum measurements alone.
I next turn to the internal structure of dark matter halos, whose formation is highly nonlinear. The spherically-averaged density of a halo is well described by the Navarro-Frenk-White (NFW) profile, a function of two parameters: concentration, which describes the density of the central region of the halo, and halo mass. These two parameters are correlated, and the resulting concentration-mass (c-M) relation is sensitive to cosmological parameters. I present a robust measurement of the c-M relation from the largest ever sample of simulated halos (~30 million) and track the evolution of individual halos to connect halo formation time and concentration.


February 1
12:00 pm - 1:00 pm


Sessler Conference Room CA

INPA guests from campus can now come up to the lab early on Fridays. The INPA Common Room (50-5026) is reserved for our guests from 10:00 am to 12:00 noon, and from 1 pm to 5 pm. Note that the seminars are now held in 50A-5132 to accommodate a larger number of attendees.

Also, on Fridays from 1:00 pm to 2:00 pm you are welcome to join the INPA Speaker for a brown-bag lunch in the small Pers Hall conference room, 54-130B.

INPA Tea Series

The Physics and Nuclear Science Divisions have together been leaders in revolutionary changes in our understanding of neutrinos and cosmology. Everyone is welcome to attend the open forum. Tea and light refreshments will be served.

INPA Common Room (50-5026)
3:30 pm

Access to the Lab

For a shuttle pass please email Paris C. Gordon. Please note: the pass is only valid for the day of the seminar.

If you have questions, comments, or suggestions please contact, preferably via email, Paris C. Gordon.