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Journal Club Seminars From 2014 - 2015


FALL 2014

October 10, 2014

Nathan's Title: "Forays in Screened Gravity"

Nathan Johnson (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

October 17, 2014

Wendell's Title: "Modification of the Brink-Axel Hypothesis for High Temperature
Nuclear Weak Interactions"

Wendell Misch (12:00-1:00)
Physics Graduate Student

October 24, 2014

Dr. Salovey's Title: "Winning the First 60 Seconds"

Todd Salovey (12:00-1:00)
Theatre Lecturer

Dr. Salovey's Abstract: In the theatre, actors' auditions are won or lost in the first 60 seconds. Casting directors say you can tell everything you need to know about an actor the minute he/she walks in the door. Business presentations are the same! The audience is making decisions about You, Your Message, Your Skills, and Your Information the MOMENT you begin. Your first 60 seconds can win a client, an account, a collaborator, even a position. In truth, your presentation is won or lost before you even walk in the door. You will begin developing the opening of an actual upcoming presentation. We will focus on the effect you wish to attain, the relationship you want to establish, as well as how to radiate confidence in yourself and your material. You can be a standing ovation presenter when you win the first 60 seconds.

October 31, 2014

Jiacong's Title: "Plasma Rotations in Tokamak"

Jiacong Li (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

November 7, 2014

NOTE: No Journal Club Today (all-day TASC meeting in SERF 383)

November 14, 2014

Pengfei's Title: "Reionization with the faintest galaxies"

Pengfei Chen (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

November 21, 2014

Mojegan's Title: "Regulation of black hole growth in low-redshift galaxies"
Praween's Title: TBA

Mojegan Azadi (12:00-12:30)
Physics Graduate Student
Praween Siritanasak (12:30-1:00)
Physics Graduate Student

November 28, 2014

NOTE: No Journal Club Today - University closed for Thanksgiving Holiday

December 5, 2014

Paul's Title: "An ultraluminous X-ray pulsar discovered in M82"
Anahita's Title: "Probing the Peak Epoch of Star Formation Rate Density (1<z<3)
with Faint Lensed Star-forming Galaxies"

Paul Hemphill (12:00-12:30)
Physics Graduate Student
Anahita Alavi (12:30-1:00)
Graduate Student, Department of Physics and Astronomy
UC Riverside

Anahita's Abstract: Obtaining a complete census of cosmic star formation requires an understanding of the faint star-forming galaxies that are beyond the detection limits of our current surveys. It is believed that these populations of galaxies play a crucial role at the reionization epoch (z>6) and maintain the ionizing background at intermediate redshifts (z>3). I will present our findings combining the power of gravitational lensing of a massive cluster, Abell 1689, with deep HST UV imaging to uncover a long-suspected underlying population of faint galaxies at z~2. Using this sample of ultra-faint galaxies, we demonstrate that the UV luminosity function has no turnover down to very faint UV magnitude of MUV ~ -13 AB mag. These galaxies are believed to have episodic bursts of star formation on short time scales (< 10 Myr) resulting in observable properties quite different from their more massive counterparts. We use a sample of low mass galaxies from hydro-dynamical simulations with bursty star formation histories (SFHs) to reconstruct the distribution of the UV continuum slopes of the faint galaxies. We find that the bursty SFHs cause a large intrinsic scatter in the UV continuum color of faint galaxies with MUV > -16 and compare these results with our measurements at z~2. I will also shortly discuss our deep UV observations on Frontier Field clusters, which will eventually triple our sample size.

December 12, 2014

Marty's Title: "The atacama cosmology telescope: lensing of cmb temperature and
polarization derived from cosmic infrared background cross-correlation"

Marty Navaroli (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

Marty's Abstract: We present a measurement of the gravitational lensing of the Cosmic Microwave Background (CMB) temperature and polarization fields obtained by cross-correlating the reconstructed convergence signal from the first season of ACTPol data at 146 GHz with Cosmic Infrared Background (CIB) fluctuations measured using the Planck satellite. Using an overlap area of 206 square degrees, we detect gravitational lensing of the CMB polarization by large-scale structure at a statistical significance of 4.5σ. Combining both CMB temperature and polarization data gives a lensing detection at 9.1σ sig- nificance. A B-mode polarization lensing signal is present with a significance of 3.2σ. We also present the first measurement of CMB lensing–CIB correlation at small scales corresponding to l > 2000. Null tests and systematic checks show that our results are not significantly biased by astrophysical or instrumental systematic effects, including Galactic dust.


January 9, 2015

Dr. Michelsen's Title: "Twice Around with Period Detection: Updated
Detection Algorithms"

Eric Michelsen (12:00-1:00)
Physics Lecturer

January 16, 2015

Dr. Skibba's Title: "nIFTy Cosmology: Comparing Models of Galaxy Clusters,
Halo Catalogs, and Galaxy Formation"

Ramin Skibba (12:00-12:30)
Assistant Project Scientist
OPEN TIME SLOT (12:30-1:00)

January 23, 2015

NOTE: CASS All-Hands-Research Meeting 12:00-1:00PM - SERF 383

 The CASS All-Hands-Research Meeting is a chance for new people to introduce themselves and discuss what they are working on. We have several new faculty and researchers, so this is a good opportunity to meet them.

Also, the meeting will give established residents an opportunity to speak about any new research they are currently doing. The atmosphere will be casual so please try to attend if you are able.

Pizza & soda will be served!

January 30, 2015

TK's Title: "Self-Interacting Dark Matter And Dark Matter halos"

TK Chan (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

TK's Abstract: Lambda Cold Dark Matter Paradigm can successfully describe the large scale structure, but recently, observations of galaxy show that galaxies are less concentrated and less cuspy than predicted in CDM simulations. Self-interacting dark matter (SIDM) is proposed to modify the sub-galactic structure without destroying the success of CDM on the large scale. We use cosmological simulations to study the effects of SIDM on the density profiles from the scales of spiral galaxies to galaxy clusters. SIDM models with cross section over dark matter mass sigma/m=0.1 cm^2/g are consistent with all observational constraints.

February 6, 2015

Dr. Muratov's Title: "Supernova remnants - beyond the spherical cow"

Sasha Muratov (12:00-12:30)
Postdoctoral Scholar
OPEN TIME SLOT (12:30-1:00)

Dr. Muratov's Abstract: Practically every subfield of Astrophysics is concerned with supernovae, as these phenomenal explosions connect subatomic physics to galactic evolution. While we know they are important, research is still being directed at studying supernovae at every scale. Even if we presume to correctly model the initial stages of the explosion, simply tracking the evolution of a supernova remnant requires sophisticated treatment of various physical phenomena. Simple analytic models (i.e. Sedov-Taylor blastwave) provide a useful framework, but can not always be applied in realistic conditions. This is a critical problem for the theoretical galaxy formation community, which ubiquitously employs the thermal energy of supernovae to sculpt galaxies, but does so without much regard to how this thermal energy is actually generated. I will discuss a recent paper entitled "Supernova Feedback in an Inhomogeneous Interstellar Medium" By Martizzi et al. (2014) which takes some steps to remedy this issue. I will first go through the homogeneous case, and present the similarities and differences seen when spherical symmetry is broken, and realistic physical conditions (i.e. turbulence in the ISM) are present. Future needs will also be discussed.

February 13, 2015

Alex's Title: "Clustering-based redshifts of WISE galaxies and quasars"

Alexander Mendez (12:00-1:00)
Postdoctoral Scholar
Johns Hopkins University

Alex's Abstract: We present the clustering-based redshift estimation of millions of extragalactic sources detected by the Wide-field Infrared Survey Explorer (WISE) using the data-driven method proposed by Menard et al. (2013). This technique derives redshift distributions from measurements of spatial correlations without any assumption on spectral energy distributions. Applying it to the entire WISE dataset as a function of brightness and colors we present the redshift distributions of WISE sources, including passive & star-bust galaxies as well as obscure and unobscured quasars.

February 20, 2015

 Title TBA

Daniella Bardalz-Gagliuffi (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

February 27, 2015

OPEN TIME SLOT (12:00-12:30)
OPEN TIME SLOT (12:30-1:00)

March 6, 2015

Dr. Gallicchio's Title: "Using quasars or CMB to test Entanglement"

Jason Gallicchio (12:00-1:00)
KICP Associate Fellow
The University of Chicago

Dr. Gallicchio's Abstract: I'll discuss a practical scheme to use photons from causally disconnected cosmic sources to set the detectors in an experimental test of Bell's inequality. In current experiments, only a small amount of correlation between detector settings could mimic the predictions of quantum mechanics. By choosing the measurement basis using pairs of quasars or patches of the Cosmic Microwave Background, observed violations of Bell's inequality would require any such coordination to have existed for billions of years --- an improvement of 20 orders of magnitude.

March 13, 2015

Stephan's Title: "Towards the first gamma rays from Galaxy Clusters:
Searches for Cosmic Rays and Dark Matter"

Stephan Zimmer (12:00-1:00)
Advanced PhD Student, Oskar Klein Center for Cosmoparticle Physics & Department of Physics
Stockholm University

Stephan's Abstract: Galaxy clusters are the most massive bound systems known in the universe and are believed to have formed through large scale structure formation. As such they host relativistic cosmic-ray (CR) populations and are gravitationally bound by large amounts of Dark Matter (DM). Both provide conditions in which high-energy gamma rays may be produced either via CR interactions with the intracluster medium or through the annihilation or decay of DM particles.

Prior to the launch of the Fermi satellite, predictions were optimistic that Galaxy clusters would be established as gamma-ray-bright objects by observations through its prime instrument, the Large Area Telescope (LAT). Yet, despite numerous efforts, even a single cluster detection is still pending. I will review the most recent methodological searches and investigate the implications that these non-detections yield, both for the extended mission of Fermi and future experiments at gamma-ray wavelengths.


April 3, 2015

Tucker's Title: "Measurements of Sub-degree B-mode Polarization in the Cosmic
Microwave Background from 100 Square Degrees of SPTpol Data"

Tucker Elleflot (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

April 10, 2015

Amol's Title: "Detection of the cosmic neutrino background via neutrino
capture on tritium"
Dr. Tejos's Title: "A statistical characterization of the intergalactic
medium in intercluster filaments"

Amol Patwardhan (12:00-12:30)
Physics Graduate Student
Nicolas Tejos (12:30-1:00)
Postdoctoral Fellow
UC Santa Cruz

Amol's Abstract: I shall discuss the physics behind cosmic neutrinos and their capture on tritium nuclei, and talk about detection prospects and physics potential of a PTOLEMY-like experiment. The talk is predominantly based on the following two references: and

Dr. Tejos's Abstract: I will describe our recent survey to constrain the properties of the intergalactic medium (IGM) in the densest filaments of the cosmic web. We selected a single bright QSO whose sightline intersects 7 independent galaxy-cluster pairs at impact parameters less than 3 Mpc, and observed it with the Cosmic Origins Spectrograph (COS) on the HST. These observations directly assess the incidence of HI and OVI gas associated with these cluster-pairs. By comparing the relative incidences as a function of distance to the cluster-pair axes, our results are consistent with a filamentary structure for the absorbing gas, and also hint towards the presence of the ellusive warm-hot intergalactic medium (WHIM). Our methodology provides a viable way to constrain the properties of the gas in the densest filaments of the cosmic web, a fundamental observable to understand galaxy formation and the evolution of baryonic matter in the Universe.

April 17, 2015

Tobias's Title: "A Variable-Density Absorption Event in NGC 3227 mapped with
Suzaku and Swift"

Tobias Beuchert (12:00-1:00)
Graduate Student
Karl Remeis Observatory, Bamberg, Germany

Tobias's Abstract: We present new time-resolved spectroscopy of the Seyfert galaxy NGC 3227. Observations of variable X-ray absorption over the past decade support the paradigm of clumpy circumnuclear gas. Eclipse events allow us to explore the properties of the clumps over a wide range of radial distances from the BLR to beyond the dust sublimation radius. The results on NGC3227 showed an eclipse event from a Swift and Suzaku campaign over several weeks in 2008. We resolve the time dependent density profile to be highly irregular and variable, in contrast to a previous symmetric and centrally-peaked event mapped with RXTE. The data indicate a filamentary, moderately ionized cloud that nearly constantly covers ~90% of the line of sight to the central engine. For the first time our results show a variety of profile shapes within the same source and therefore provide an excellent opportunity to further test models describing the formation and dynamics of individual clouds or filaments as well as their distances from the supermassive black hole. We also study the Spectral Energy Distribution from the Infrared to the X-rays to get a better handle on the physics of the system.

April 24, 2015

Alexey's Title: "Transport of Flavored Neutrinos in Astrophysical Environments"

Alexey Vlasenko (12:00-1:00)
Postdoctoral Scholar

Alexey's Abstract: Neutrinos play an important role in hot, dense environments, such as the early Universe, core collapse supernovae and compact object mergers. Neutrinos can transport energy, entropy and lepton number over long distances and give rise to observable signals that can provide insights both into fundamental neutrino physics and into the nature of these environments. The interplay of neutrino transport and flavor evolution can be vitally important both to the dynamics of neutrino-affected environments and to the observable signals, but it is currently poorly understood. I will describe the general formalism by which one can treat the transport of flavored particles and discuss the applications of this approach to supernovae and to the early Universe.

May 1, 2015

Scott's Title: "Remeasurement of Primordial Deuterium in quasar absorption lines"

Scott Gustafson (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

Scott's Abstract: Original Paper's Title: A robust deuterium abundance; re-measurement of the z = 3.256 abs- orption system towards the quasar PKS 1937-101:

Abstract: I will be presenting on a recent paper by Riemer-Sorenson et al concerning the remeasurement of the Deuterium-to-Hydrogen abundance ratio (D/H) towards quasar PKS 1937−101. D/H has been an important means of measuring the baryon density of the universe, independent of the CMB, but when used in conjunction with other primordial abundances, is also a powerful probe of non-standard physics. Literature shows a spread in values of D/H that cannot be attributed to random error alone. In this talk I will be discussing the authors' approach towards revisiting a previously published system with better data in an attempt to understand the underlying systematic errors.

May 8, 2015

Dr. Melis's Title: "Stochastic Processes in Planetesimal Belts"

Carl Melis (12:00-12:30)
Assistant Research Scientist
OPEN TIME SLOT (12:30-1:00)

May 15, 2015

Dr. Markowitz's Title: "An observed correlation between plume activity and tidal
stresses on Saturn's moon Enceladus"

Alex Markowitz (12:00-12:30)
Assistant Research Scientist

May 22, 2015

Kavon's Title: "APOLLO eclipse results and alternate theories of gravity"

Kavon Kazemzadeh (12:00-12:30)
Physics Undergraduate Student
OPEN TIME SLOT (12:30-1:00)

May 29, 2015

James's Title: TBA
Fred's Title: TBA

James Tian (12:00-12:30)
Physics Graduate Student
Fred Matsuda (12:30-1:00)
Physics Graduate Student

June 5, 2015

Marcel's Title: "ALMA at high redshift: Success or Dud?"

Marcel Neeleman (12:00-12:30)
Physics Graduate Student
OPEN TIME SLOT (12:30-1:00)

Marcel's Abstract: I will discuss some of the latest work on using ALMA to detect and study galaxies at high redshift. In particular I will discuss the recent work that will be published in Nature by Capak et al. ( describing the detection of atomic carbon at redshifts 5-6. I will try to answer the question of how much we can learn about high redshift galaxies with ALMA.