Seminars 2005-2006 of potential interest to people in the Berkeley Cosmology Group

May 2006:
May 2, Tuesday 1:10 pm ( will last 1 hour, not 50 min)
Joel Primack, UCSC
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Galaxy Mergers: Simulations, Observations, and Active Galactic Nuclei (AGN)"
In this informal talk, I will summarize the large suites of high resolution simulations of galaxy encounters that my current and former PhD students have been running and analyzing, and comparisons with observational data especially from the ongoing DEEP2 survay. In particular, I will discuss what the DEEP data tell us about the morphologies of galaxies that host AGNs, and the implications for theoretical models that try to connect the evolution of AGNs with that of their host galactic spheroids.
May 2, Tuesday 5:45 pm
Joel Primack and Nancy Abrams, UCSC
2050 Valley Life Sciences Building
"The View from the Center of the Universe" (Sackler Lecture)
Cosmology is going through a scientific revolution that is creating humanity's first picture of the universe that might actually be true. This lecture explains and visualizes the evolution of the Universe, the fact that the universe is made mostly of dark matter and dark energy with visible matter making up only about half a percent of the total, and the remarkable fact that humans - and indeed intelligent life anywhere in the universe - must have a size that is in the middle of all possible size scales. Joel and Nancy alternate frequently during the presentation, presenting scientific and philosophical viewpoints. They show spectacular new images and videos, using both updated ancient symbols and the latest astronomical data and simulations. They also use humorous cartoons to illustrate how cosmological ideas have widespread cultural implications. The talk is both entertaining and educational, and it can be enjoyed by everyone from people who know nothing about modern astronomy to experts in the field.
May 16, Tuesday 1:10 pm
Zheng Zheng, IAS
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Cosmology and Galaxy Evolution from Galaxy Clustering"
Contemporary galaxy redshift surveys have enabled us to measure galaxy clustering in great details. However, the explanation of galaxy clustering and its use to constrain cosmological model are complicated by the existence of galaxy bias, the difference between galaxy distribution and matter distribution. Galaxy bias encodes information about galaxy formation processes and an empirical determination of it can put useful constraints on galaxy formation models. A complete description of galaxy bias can be achieved at the level of individual dark matter halos in the framework of the Halo Occupation Distribution (HOD). Within the HOD framework, I first discuss a theoretical investigation of the possibility that we constrain cosmological parameters from a variety of galaxy clustering statistics, and at the same time we infer galaxy bias. Then I present HOD modeling results of galaxy clustering from the SDSS and the DEEP2 surveys, which probe galaxy populations at z~0 and z~1, respectively. Based on the assembly history of dark matter halos, I attempt to establish an evolutionary link between DEEP2 and SDSS galaxies and thus infer interesting information about galaxy evolution from z~1 to z~0.

May 22, Monday
Cosmology in Northern California Workshop (LBNL)
Talks by postdocs, grad students and new faculty to the region
Discussions: Wide Field Surveys and Multi-messenger Astronomy

May 23, Tuesday 1:10 pm (RAL/Cosmoloy seminar)
Emma Ryan-Weber, IOA
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Gas-rich Galaxies in a Gas-rich Cosmic Web"
The location of Lyman-alpha and metal absorbers provides a map of the cosmic web between galaxies. I will talk about the connection between galaxies and the intergalactic medium. Firstly, results from the cross-correlation of Lya absorbers and galaxies from the HI Parkes All Sky Survey (HIPASS) at z=0. The analysis shows that Lya absorbers are embedded in galaxy groups and large-scale filaments, particularly those that comprise gas-rich galaxies. Secondly, I will present new results on the highest redshift CIV absorption system known to-date, which suggest that a large fraction of intergalactic metals were already in place at high redshift, indicating an epoch of early metal enrichment.

April 2006:

April 3 (Monday) 4:30 pm (Physics Colloquium)
Gus Evrard , U Michigan and UCB
1 LeConte Hall
"Before The Deluge: Cosmology With Galaxy Cluster Surveys"
The population of galaxy clusters offers a means to survey the volume element and growth function of the cosmological model that describes our universe, thereby testing the nature of dark matter and dark energy. This talk will provide an overview of the theoretical, observational and computational elements of this endeavor, and offer some insight on what's to be gained from the deluge of survey data coming in the next 5 - 10 years.

April 4 (Tuesday) 1:10 pm
Michael Brown, Princeton
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"The Evolution of Red Galaxies since z=1"
Red galaxies contain the bulk of the stellar mass at low redshift, and understanding their evolution is crucial if we are to understand galaxy formation as a whole. Using the 9 square degree Bootes field of the NOAO Deep Wide-field and Spitzer IRAC shallow surveys, I have measured the space density and clustering of 41000 red galaxies from z=0.2 to z=1. While the stellar mass within red galaxies has grown since z=1, this is associated with red galaxies which are L* or fainter. The space density and clustering of the most luminous red galaxies indicates they were largely assembled at z>1. Models with little star formation and few mergers can explain the evolution of the most luminous red galaxies, and dry mergers play only a minor role.

April 11 (Tuesday) 1:10 pm
Kentaro Nagamine , UCSD
544 Campbell Hall (also videoconferenced to LBL 50-5131)
" DLA and Galaxy Formation"
Damped Lyman-alpha Systems (DLAs) are very useful probes of high-redshift galaxy formation. I this talk I will discuss the current issues and problems in the studies of DLAs using cosmological hydrodynamic simulations. In particular, I will focus on the effects of feedback on various physical quantities such as the neutral hydrogen mass density in the Universe, column density distribution function, DLA cross section & rate-of-incidence, distribution of DLAs as a function of dark matter halo mass, physical size and number density of DLAs, and metallicity of DLAs. Finallly, as an alternative way to study DLA host galaxies, we propose the observation of [CII] emission line from high-z galaxies, which might become feasible with the ALMA in the future.

April 18 (Tuesday) 1:10 pm
Darren Croton , UCB
544 Campbell Hall (also videoconferenced to LBL 50-5131)
" The many lives of AGN: from super-massive black holes to host galaxy colours and luminosities"
I use a detailed self-consistent model of galaxy formation and the Millennium Run LCDM N-body simulation to explore the evolution of the galaxy population, including super-massive black hole growth, in a cosmological context. Motivated by observations of local cooling flow systems I propose two modes of AGN activity, the merger driven high energy 'quasar' mode and the quiescent low energy 'radio' mode. I focus on the effect that 'radio' AGN feedback has on cooling flows in massive systems, and discuss the impact that such cooling suppression has on the final galaxy properties. This becomes important for both the build up of mass on the red sequence and the field population as a whole.

April 25, Tuesday 1:10 pm
Andreas Faltenbacher, UCSC
544 Campbell Hall (also videoconferenced to LBL 50-5131)
" The impact of tidal forces on sub-halo distributions"
The spatial and velocity distributions of subhalos in N-body clusters depend on the subhalo selection criteria. For comparison with observations it is essential to know how to populate subhalos with galaxies. Recently it has been proposed to associate the amount of starlight with the subhalo mass before accretion onto host halo. This recipe generates spatial distributions of subhalos which resemble observed galaxy distributions in clusters. On the other hand a selection by current subhalo mass cannot reproduce the spatial distributions of galaxies. This behavior arises because subhalo samples selected by current mass are more strongly affected by tidal forces than samples selected by the mass at the time of accretion. In my talk I will discuss the impact of these selection criteria on the velocity distributions of subhalos and how these findings may be used to interpret the velocity distributions of galaxy clusters.

March 2006:

Mar. 1 (Wednesday) 12:10 pm
Risa Wechsler, KICP, U Chicago
544 Campbell Hall
"Lighting up the dark: Connecting galaxies to mass"
Many of the most vital questions in cosmology require a detailed understanding of a simple question: How does mass connect to light? Making this connection, often described by the galaxy "bias", is essential both to use galaxy clustering to constrain cosmological models and the nature of dark energy, and to develop a physical understanding of the origin of galaxy properties and their correlations. I will describe several advances towards making this connection, which combine the results of numerical simulations with observations of galaxy clustering and of galaxy clusters. I will describe results from a simple yet accurate model which connects dark matter subhalos to galaxies, and is able to reproduce nonlinear galaxy clustering as a function of luminosity from z~5 to the present. This indicates that gravity and dynamical evolution of the dark matter halos are the main factors responsible for the spatial distribution of galaxies. I will then discuss the validity of a central assumption often used to connect galaxies to halos: that their clustering properties depend only on the mass of their hosts. Finally, I will describe a method of connecting galaxies to the mass distribution which is applicable to very large volume simulations, and show how it can be used in combination with large cluster surveys to pin down cosmological parameters and the nature of dark energy.

Mar. 7 (Tuesday) 1:10 pm
Elena Pierpaoli, Caltech
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Cosmological insights on particle physics"
The results from the last decade on the Cosmic Microwave Background and large scale structure have set major milestones in our understanding of the Universe. We now know the main cosmological parameters with very high precision and we are able to constrain particle physics with cosmology. I will illustrate four different examples of how neutrino properties may impact the cosmological observables and show that cosmology can now provide tight limits on neutrino physical properties. An analogy between neutrino's and gravitational wave's cosmological behavior also allow to constrain the energy density of the gravitational wave background. Finally I will discuss how future cosmic microwave background experiments, also detecting clusters of galaxies through the Sunyaev-Zeldovich effect, may improve our current understanding.

Mar. 16 (Thursday) 4:10 pm (Astronomy Colloquium)
Matthias Bartelmann , Heidelberg
1 LeConte Hall
"Early dark energy and late cosmic structures"
Most models for dynamical dark energy predict a non-vanishing dark-energy density only at the late stages of cosmological evolution. Models with early dark energy, which have a small, but finite dark-energy density even at early times, lead to pronounced changes in non-linear structure formation. I shall describe how such models can be tested with a broad variety of cosmological observables, and that several observational facts may already argue for early dark energy.

March 21 (Tuesday) 1:10 pm
Olivier Dore, CITA
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Mapping the polarized sky with WMAP: methods and cosmological insights"

March 21 (Tuesday) 4:00 pm (not 4:10 pm) (RPM at LBNL)
Olivier Dore, CITA
Building 50A, Room 5132 (LBNL)
"Mapping the polarized sky with WMAP: methods and cosmological insights"
Mar. 28 (Tuesday)
spring break, no talk scheduled.

February 2006:
Feb. 3 (Friday) 12:00 pm
Phil Marshall, SLAC
LBL Bldg. 50, room 5026 (the INPA common room)
"Surveying for Strong Gravitational Lenses"
Gravitational lensing provides a unique view of the mass in the Universe: multiple imaging by galaxies permit a number of interesting experiments on the dark matter content of galaxies, and cosmology. Strong lenses are at present considered rare events: all the above-mentioned experiments would benefit from much larger samples of objects. I will describe strong lens surveys being planned at KIPAC using two telsecopes due to come online in the next decade or so: SNAP and LSST. Given these timescales, I will also present preliminary results from a precursor survey (using data from the HST archive) and discuss the technology development needed to make strong lens surveys work.

Feb. 7 (Tuesday) 1:10 pm
Jeff Newman, UCB
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"New Results from the DEEP2 Redshift Survey: From Fine Structure to Large-Scale Structure"
The DEEP2 Galaxy Redshift Survey is the first project to study the distant Universe by obtaining a dataset comparable in nature and size to recent local surveys. DEEP2 was designed to measure both the properties of galaxies at redshift z~1 and their distribution in space, making possible a number of unique tests of both galaxy evolution and cosmology. In this talk, I will first provide an overview of multiwavelength efforts now underway in one of the four DEEP2 fields, the Extended Groth Strip, which has become the focus of both deep and wide imaging from X-ray to radio wavelengths. I will then briefly review tests for both temporal and spatial variation in the value of the fine structure constant which we have performed using DEEP2 data. Finally, I will discuss several lines of evidence from DEEP2 indicating that galaxy groups are critical to the formation of typical early-type/red sequence galaxies seen today, and illustrate ways in which low-redshift surveys can help us to understand phenomena observed at z~1.

Feb. 9 (Thursday) 4:10 pm (Astronomy Colloquium)
Alberto Bolatto , UCB
1 Le Conte Hall
"The Primitive Universe, Near and Far"
The study of primitive galaxies, whether in the local universe or at cosmological distances, is one of the most active and rapidly evolving fields in present day Astronomy. New and more capable millimeter-wave instruments, such as CARMA and ultimately ALMA, will revolutionize our understanding of the gas content, the evolutionary state, and the dynamics of these objects. With an eye toward applications at high redshift, I will discuss some of the results and outstanding puzzles presented by nearby low mass systems akin to primeval galaxies. In particular, I will present a detailed study of the relationship between molecular gas and star formation in small galaxies, as evidenced by millimeter-wave interferometry and far infrared Spitzer observations. Finally, I will discuss some of the ongoing CARMA technical developments at Berkeley, and the interesting projects that these developments make possible: measuring rotation curves at z~6.4, and finding the sources that reionized the universe.

Feb. 14 (Tuesday) 1:10 pm
Tommaso Treu, UCSB
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Cosmic evolution of spheroids: stellar populations, dark matter halos, and supermassive black holes"
I will present new observational results on the formation and evolution of spheroids (i.e. elliptical and S0 galaxies and bulges of spirals). I will discuss the inferred properties of their stellar populations, dark matter halos, and supermassive black holes in the range z=0-1 in the context of the currently popular hierarchical model of galaxy formations.

Feb. 15 (Wednesday) 12:10 pm (Wednesday lunch: informal)
Becky Stanek and Gus Evrard, U Michigan
501 Campbell Hall
Galaxy cluster informal talk/discussion

Feb. 16 (Thursday) 4:10 pm (Astronomy Colloquium)
Pieter van Dokkum , Yale
1 Le Conte Hall
"The nature of massive galaxies at z~2.5 (and beyond)"
The "standard" method for selecting high redshift galaxies is the highly successful Lyman break technique, developed by Steidel and collaborators. However, recent advances in instrumentation have made it possible to select galaxies in complementary ways, and it has become clear that the high redshift universe is much more complex than previously thought. A new study of a stellar-mass limited sample of high redshift galaxies shows that Lyman break galaxies only comprise ~20% of massive galaxies at 2 < z < 3, which means that so far we have only studied a small, biased fraction of the massive galaxy population at early times. The talk will highlight these new results, and discuss current efforts with Spitzer, HST, Chandra, Gemini, and premier ground-based telescopes to select and study unbiased samples of massive high redshift galaxies. The goal for the future is to directly measure kinematics of these galaxies: this will be possible with ALMA (for gas-rich galaxies) and with 30m optical/NIR telescopes (for passively evolving galaxies).

Feb. 21 (Tuesday) 1:10 pm
Steve Furlanetto, Yale
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"The Dark Ages, the Twilight Zone, and the 21 cm Transition"
The last frontiers of observational cosmology are the "dark ages" and the "twilight zone," during which structures grow from the tiny perturbations seen in the cosmic microwave background to the first generations of stars and galaxies that reionize the universe. Unfortunately, these epochs are particularly difficult to study, and new approaches are urgently needed to understand them. I will describe one of the most exciting of these approaches: the 21 cm transition of neutral hydrogen. I will review how it can be used to study linear density fluctuations at z>50, the formation of the cosmic web and the first luminous sources, and reionization itself.

Feb. 22 (Wednesday) 4 pm
Uros Seljak , Trieste & Princeton
LBL, INPA conference room, room 50-5026
"What can cosmological observations do for particle physics?"
Cosmological observations can provide answers to many questions of interest to particle physics. In my talk I will discuss a few examples of current interest, such as sterile neutrinos as the dark matter, signatures of string physics in cosmology, neutrino mass limits, inflation and modified gravity.

Feb. 23 (Thursday) 11:10 am (Special Talk)
Uros Seljak , Trieste & Princeton
544 Campbell Hall
"Three pillars of large scale structure: galaxies, weak lensing and Lyman alpha forest"
Besides cosmic microwave background anisotropies the three tracers of large scale structure most commonly used in analyses are galaxy clustering, weak lensing and Lyman alpha forest from quasar spectra. I will review their current observational status focusing on results from the current state of the art surveys such as the Sloan Digital Sky Survey. I will also discuss their complementarity and future promise.

Feb. 24 (Friday) 12:10 pm (Journal Club time slot)
Joe Hennawi , UCB
544 Campbell Hall
"New Insights into Quasar Environments from Close Quasar Pairs"
Close sub-arcminute quasar pairs project to a proper distance < 300 kpc/h --- which is an extremely interesting scale for a variety of cosmological phenomena. For example, close pairs resolves the radii (R ~ 80 kpc/h) of the massive dark halos which host quasars, it is comparable to the Einstein radii of group and cluster scale gravitational lenses, it corresponds to a light crossing time which is ~ 10 % of the average quasar lifetime (~10^7 yrs), and at such small distances from a luminous quasar, the flux of ionizing photons is > 100 times that of the ambient UV background.

I will discuss a sample of about 200 new sub-arcminute quasar pairs, discovered from an observing campaign to find close companions around the Sloan Digital Sky Survey (SDSS) quasars. Using this sample, I present the first measurement of the small scale (10 kpc/h < R < 400 kpc/h) clustering of quasars at z ~ 1.5, and I will discuss tantalizing new evidence that quasars cluster in a dramatically different way than galaxies at z ~ 4. With close pairs of quasars at different redshifts, a background quasar sightline can be used to study a foreground quasars environment in Ly-alpha absorption. I will discuss the manifold cosmological applications of these rare projected sightlines: they provide new laboratories for studying the faint fluorescent recombination radiation from the high redshift Universe, they constrain the environments, emission geometry, and radiative histories of quasars, and can shed light on the distribution of neutral gas in high redshift proto-galaxies.

Feb. 27 ( Monday) 12:10 pm (TAC talk)
Peder Norberg, Edinburgh
544 Campbell Hall
"On the luminosity dependence of quasar clustering"
We present detailed clustering measurements for a flux limited sample of ~14,000 quasars extracted from the 2QZ survey in the redshift range 0.8 < z < 2.1 . We find clear evidence for an increase of the clustering amplitude with lookback time. Using HOD models, we find that 2QZ quasars sit in haloes with M > 1012 M_sun and that the mean mass of their host haloes is of the order of 1013 M_sun.

We then split each redshift interval into several luminosity intervals, for which we estimate the quasar projected auto and cross-correlation functions. We find that models with luminosity dependent clustering tend to be statistically favoured, but larger datasets are needed to rule out / confirm current models for luminosity segregation.

Feb. 28 (Tuesday) 1:10 pm
Katie Freese, U. Michigan
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"A New Approach to Inflationary Cosmology and the Cosmological Constant Problem"
Inflationary cosmology was proposed in 1980 as a solution to several puzzles in the standard Hot Big Bang cosmology. An early superluminal growth period of the universe drives the universe to becomes smooth and flat on large scales and eliminates excess magnetic monopoles. Recently we proposed a new approach: in "Chain Inflation", the universe tunnels through a series of minima, obtaining a tiny bit of inflation at each stage. This paradigm applies in two physical situations. First, there are very large numbers of vacua in the stringy landscape, and the universe may tunnel from one to another until it reaches the bottom of the potential. Second, there is the exciting development that inflation may be caused by the QCD axion, which was proposed for completely different reasons in particle physics and is detectable in ongoing experiments. Recently we also noticed that the same form of the potential may provide a solution to the cosmological constant problem.

January 2006:
Jan. 12 (Thursday) 4 pm, LBL-RPM
Nikhil Padmanabhan, Princeton
LBL, Bldg. 50A, Room 5132
"Cosmology with Multi-band Imaging Surveys: Present Efforts and Future Prospects"

Jan. 17 (Tuesday) 1:10 pm
Adam Stanford, Livermore
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Panchromatic Surveys for Galaxy Clusters"

Jan. 19 (Thursday) 4:10 pm (Astronomy Colloquium)
Emanuele Daddi , NOAO
1 Le Conte Hall
"Formation and assembly of massive galaxies at z=2"
The formation and assembly of massive galaxies is a central problem for galaxy evolution. Recently we have shown that massive galaxies are common in the field all the way to redshift at least 2, and come in two main flavors: red and dead galaxies and vigorous dust-reddened starbursts. We have calibrated a new selection technique based on BzK photometry that allows us to obtain virtually complete samples of near-IR luminous galaxies in the range 1.4 < z < 2.5. I will present results from our ongoing efforts to characterize the properties and nature of these sources, and how they relate to the predictions of current galaxy formation theories.

Jan. 30 (Monday) 12:10 pm (TAC seminar)
Miguel Morales , CfA
544 Campbell Hall
"Radio Observations of the Epoch of Reionization"
Highly redshifted 21 cm neutral hydrogen emission from the Epoch of Reionization (EOR) is a unique cosmological probe, and planned low frequency radio observations could revolutionize our understanding of galaxy and structure formation and the emergence of the first luminous objects. However, EOR observations are complicated by strong foreground contamination and stringent instrumental requirements. In this talk, I will review the observational signatures of the Epoch of Reionization and how the faint 21 cm emission can be extracted from the foreground signals, and describe the observations my colleagues and I are undertaking with the Very Large Array (VLA) and the Mileura Widefield Array - Low Frequency Demonstrator (MWA-LFD).

Jan. 31 (Tuesday) 1:10 pm
Jeremy Tinker, U. Chicago
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Cosmological Implications of Halo Mass-to-Light Ratios"
Cluster mass-to-light ratios have long been at odds with the cosmological models of the day (past and present), in that they imply a lower matter density than what is inferred from other methods. By modeling the observed galaxy two-point correlation function with the halo occupation distribution (HOD), one can predict the mass-to-light ratios of cosmic structure, from Milky Way-type halos to poor groups to rich clusters and beyond. I will compare the HOD predictions to results from the CNOC survey, CAIRNS survey, and the group catalog of the 2dF survey. The results from all three data sets, which span more than three decades in mass, are inconsistent with the current concordance cosmology, implying either a lower matter density, a lower amplitude of matter clustering, or both. I will also discuss questions that have arisen recently regarding the inherent assumptions in the HOD, namely the environmental independence of galaxy occupation. I will present a defense of the HOD with theoretical and observational tests of this assumption.

December 2005:

Dec. 5 (Monday) 4:30 pm (Physics Colloquium)
Jeffrey Newman , LBL
1 LeConte
"Constraining New Physics with the DEEP 2 Redshift Survey"
Over the last three years, the DEEP2 Redshift Survey has obtained spectra of nearly 50,000 galaxies at high redshift to study the evolution of galaxies and the large-scale structure of the Universe. We have now used a subset of this data to perform a robust test for changes in the value of the fine structure constant, alpha, over the last 7 billion years by measuring the wavelength separation of a doublet of emission lines produced by twice-ionized oxygen. In addition, we take advantage of the fact that DEEP2 surveys four widely-separated regions of sky to test for spatial variation in alpha at constant time. Finally, I will discuss the use of DEEP2 data to measure the dark energy equation of state parameter, w, by measuring the abundance of galaxy groups and clusters at high redshift.

Dec. 6 (Tuesday) 12:10 pm please note special time!!
Naveen Reddy, Caltech
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"A Census of Optical and Near-IR Selected Galaxies at Redshift Z~2"
We use extensive multi-wavelength data in the GOODS-North field to construct and draw comparisons between samples of optical and near-IR selected star-forming and passively evolving galaxies at redshifts 1.4

Dec. 6 (Tuesday) 4:00 pm
Nick Kaiser, Hawaii
LBL, 50A-5132
The Pan-Starrs Survey Telescope Project
The Institute for Astronomy at the University of Hawaii is developing a large optical/near-IR survey telescope system; the Panoramic Survey Telescope and Rapid Response System. Pan-STARRS will consist of an array of four 1.8m telescopes with very large (7 square degree) field of view, giving it an etendue larger than than that of all existing survey instruments combined. Each telescope will be equipped with a 1.4 billion pixel CCD camera with low noise and rapid read-out, and the data will be reduced in near real time to produce both a cumulative image of the static sky and difference images, from which transient, moving and variable objects can be detected. Pan-STARRS will be able to scan the entire visible sky to approximately 24th magnitude in less than a week, and this unique combination of sensitivity and cadence will open up many new possibilities in time domain astronomy. A major goal for the project is to survey potentially dangerous asteroids, where Pan-STARRS will be able to detect most objects down to 300m size, much smaller than the km size objects accessible to existing search programs. In addition, the Pan-STARRS data will used to address a wide range of astronomical problems in the Solar System, the Galaxy, and the Cosmos at large. In this talk I will describe the science drivers for the project; the technical design; and give an update on the current status and future time-line of the project.

Dec. 8 (Thursday) 4:10 pm
Pieter Van Dokkum, Yale
2 LeConte Hall
"The formation of elliptical galaxies"
Elliptical galaxies dominate the high mass end of the galaxy mass function, and their status at the top of the food chain implies that they provide strong constraints on hierarchical galaxy formation models. I will review recent progress in our understanding of the star formation epoch and the assembly time of today's elliptical galaxies. The focus will be on the redshift range 02.

Dec. 9 (Friday) 3:00 pm
Eric Linder, SSL/LBL
SSL, ( SSL Colloquium)
"Seeing the Nature of the Accelerating Physics: It's a SNAP"
The acceleration of the cosmic expansion is a fundamental challenge to standard models of particle physics and cosmology. The new physics of dark energy may lie in the nature of gravity (when is gravity no longer attractive?), the quantum vacuum (does nothing weigh something?), or extra dimensions (is nowhere somewhere?). I present an overview of the puzzles and possibilities of dark energy and the means for unraveling them through cosmological probes. Next generation experiments such as the Supernova/Acceleration Probe (SNAP) satellite would measure the supernova distance-redshift relation to high accuracy and map the evolution of structure and dark matter through gravitational lensing. These observations will explore the frontiers of physics and aim to uncover what makes up the still unknown 95% of our universe, while producing astronomical images equal to a million Hubble Deep Fields.

Dec. 9 (Friday) 12:10 pm
Philip Hopkins, Harvard/CfA
544 Campbell Hall
"Black Hole Feedback: the Critical Link in Uniting Mergers, Quasars, and Red Galaxy Formation"
Observations are increasingly probing each aspect of the evolutionary model for starbursts, quasars, and spheroidal galaxies, in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing intense starbursts and feeding buried growth of supermassive black holes until feedback expels gas and renders a briefly visible optical quasar. These observations imply with increasing emphasis that black hole feedback must play a critical role. Using a large suite of hydrodynamical simulations of galaxy mergers, which span a wide range in the space of possible initial conditions and incorporated physics, we quantify the relation between the different stages of this evolutionary sequence and their properties. The quasar lifetime and obscuring column density depend on both the instantaneous and peak luminosities of the quasar, and the lifetime and light curve decay very differently in self- regulated, feedback-dominated quasar evolution. We determine these dependencies and use them to de-convolve the observed quasar luminosity function to determine the formation and evolution of quasars and to map this distribution to others in the evolutionary sequence. With this formalism, we predict a wide variety of black hole properties, the X-ray background spectrum, red galaxy distributions, and ongoing merger starburst fractions and distributions at redshifts z=0-6, and the structure and signatures of feedback- driven outflows. Black hole feedback is a vital link in these distributions, and with (but not without) it, these distributions are all self-consistent and their statistics follow from their being manifestations of the same fundamental evolutionary process.

November 2005:

Nov. 1 (Tuesday) 1:10 pm
Catherine Heymans, UBC
544 Campbell Hall (also videoconferenced to LBL 50-5131)
STEPs towards high precision cosmology with weak gravitational lensing
Weak gravitational lensing has shown itself to be a promising new tool for cosmology. Technically, however, it is rather challenging to detect, as lensing requires the measurement of the weak cosmological distortion that is induced in the shapes of galaxy images, in the presence of stronger image distortions resulting from the atmosphere, telescope and camera. The unique qualities of weak lensing as a dark matter and dark energy probe demand that all technical challenges are met and overcome and for this reason the Shear TEsting Programme, STEP, began. In this talk I will review the different methods currently used to detect weak gravitational lensing and present the first results from STEP detailing how accurate each of these measurement methods are. I will then discuss how these results impact on current and future lensing surveys. Aside from the challenging technical issues, lensing is often viewed as a very clean cosmological probe. I will ask if there are any 'showstoppers' with this technique and review recent work on intrinsic correlations that can mimic weak lensing and the possible ways of minimising these physical effects.

Nov. 8 (Tuesday) 1:10 pm
NO talk
544 Campbell Hall (also videoconferenced to LBL 50-5131)

Nov. 15 (Tuesday) 1:10 pm
Priya Natarajan, Yale
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Probing the nature of dark matter via gravitational lensing,"
We obtain constraints on the nature of dark matter by combining strong and weak lensing analysis for a sample of HST clusters. The mass function of substructure and the distribution of tidal radii are used to constrain the equation of state of dark matter. Substructure in massive lensing clusters can be effectively mapped by quantifying anisotropies in the observed shear field. We also present new results of a detailed comparison of the sub-halo mass function obtained from lensing with that of dark matter halos in simulated clusters in the Millennium Run.

Nov. 16 ( Wednesday) 12:30 pm (4D Seminar)
Eric Linder, UCB
50-5026 LBL
"Dynamics of Dark Energy"

Nov. 17 ( Thursday) 4:00 pm (LBNL RPM)
Don Neill, U Victoria
Building 50 Auditorium LBL
"Cosmology and SN Ia Rates with the SNLS"
The Supernova Legacy Survey (SNLS) has completed the first two years of its five-year program and cosmology results from the first year are in press. This unprecedented data set is ripe to begin examining the properties of Type Ia Supernovae (SNe Ia) with the aim of shedding light on their properties as standard candles and refining their use as cosmological probes. I have begun a study of the rate density of SNe Ia in the redshift range 0.2 < z < 0.6 and, after a brief review of the cosmology results, will present a description of this study. I will review some recent models connecting cosmic star formation history with the observed SN Ia rate density evolution. Now that our samples in various redshift bins are getting large and as a result, statistical errors are getting small, the dominant factor preventing a meaningful distinction between models is survey systematics. I will describe how SNLS will help to control these systematics and begin narrowing in on the progenitor population of SNe Ia.

Nov. 22 (Tuesday) 1:10 pm
Viviana Acquaviva, SISSA
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Investigating dark energy with CMB lensing"
This talk describes work on constraining the expansion history of the universe using lensing of CMB anisotropies by large scale structure. We review the modifications to the standard picture of weak lensing required in the context of general dark energy cosmologies, and then focus on the lensing peak in the CMB polarization B modes. Variations in the dark energy equation of state may induce variations in the lensing peak by several ten percent, within present constraints. In fact, the CMB lensing cross section picks up most of its power at z ~ 1, cutting out both the local and early universe and thus emphasizing the sensitivity to dynamics at the onset of acceleration. We present results for the LambdaCDM model and for two Quintessence models, quantify the scientific impact of this method on constraining dark energy parameters, and compare available precision for some forthcoming CMB polarization probes.
Nov. 22 (Tuesday) 4 pm, LBL-RPM
Christian Reichardt, Caltech
LBL, Bldg. 50A, Room 5132
"Cosmology with ACBAR"

Nov. 29 (Tuesday) 1:10 pm
Brice Menard, IAS
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Cosmic magnification & cosmic reddening"
The large-scale distribution of matter distorts and magnifies the images of distant objects. Whereas the first effect, also called cosmic shear, was detected in 2000, the cosmic magnification was only observed recently. I will present the detection obtained with the SDSS and show how distant quasars are magnifies by intervening matter, and what we can learn from such a measurement. I will also discuss a related work aimed at measuring the effects of dust reddening on cosmological scales.

October 2005:

Oct. 4 (Tuesday) 1:10 pm
no talk

Oct. 6 (Thursday) 4:10 pm (Astronomy Colloquium)
Chris Kochanek , Ohio State
2 Le Conte Hall
"Halo Substructures"
The halos of galaxies are filled with "substructure" -- objects which make the gravitational potential differ from that of a smooth, centrally concentrated density distribution. Candidates for substructure include not only visible stars and satellite galaxies but also the more the more exotic possibility of dark matter only satellites. The latter possibility is particularly interesting because CDM models predict the existence of many more small halos than are observed. Both dark and luminous substructures of distant galaxies can be detected through their effects on the fluxes of the images of gravitational lenses because the image fluxes are unstable to local perturbations in the potential. We will use the lenses as tools to search for CDM substructure, search for stars in the halos of galaxies, and study the structure of quasar emission regions.

Oct. 10 (Monday, TAC seminar) 12:10 pm
Peng Oh, UCSB
544 Campbell Hall
"Spectral Signatures of Early Galaxy Formation"
I discuss two observational probes of early galaxy formation and reionization. The primary spectral line signature of ionizing sources is Ly-alpha emission. I discuss a new algorithm for computing radiative transfer through a multi-phase dusty interstellar medium, and several applications. In particular, I show that preferential transmission of resonance line photons is possible, which may explain the puzzlingly high equivalent widths seen in many high-redshift galaxies. As for the intergalactic medium, our primary observational constraints come from quasar absorption line spectra, and (in the years to come) 21cm observations. I discuss interpretation of existing quasar spectra, and discuss prospects for analyzing the rich 21cm data sets which should be coming our way in the next few years.

Oct. 11 (Tuesday) 1:10 pm
Raul Jimenez, U Penn
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"The Atacama Cosmology Telescope: Probing Fundamental Physics Through Measurements of Cosmic Structure"
The Atacama Cosmology Telescope (ACT) is a mm telescope designed to map the CMB at angular scales of 1'. It will start operating in the Atacama desert in the Fall of 2007 and will cover a region of about 200 sq. deg of the sky and will obtain maps of the CMB with a sensitivity of 2micro Kelvin per pixel. It has three filters designed to discover clusters of galaxies through the SZ effect. In this talk I will describe the experiment and will concentrate on the observable quantities it provides to constrain the nature of dark energy. In particular I will show how ACT will provide multiple probes of the growth factor of density and velocity and distances at different redshifts in the Universe.

Oct. 12 (Wednesday lunch) 12:10 pm
Licia Verde, U Penn
501 Campbell Hall
"Optimizing cmb polarization experiments to constrain inflationary physics"
We quantify how to optimize current-technology cosmic microwave background polarization experiments in order to learn about inflationary physics. We consider space-based, balloon-borne and ground-based experiments. We find that foreground contamination and residuals from foreground subtraction are ultimately the limiting factors in detecting a primordial gravity wave signal. To produce a clearly measurable tensor component in a realistic CMB experiment, inflation must either involve large-field variations, Delta phi ~ 1 or multi-field/hybrid models. Hybrid models can be easily distinguished from large-field models due to their blue scalar spectral index. Therefore, an observation of a tensor/scalar ratio and n < 1 in future experiments with the characteristics considered here may be an indication that inflation is being driven by some physics in which the inflaton cannot be described as a fundamental field.

Oct. 13 (Thursday) 4:00 pm ( LBL RPM)
Nikhil Padmanabhan , Princeton
LBL 50A-5132
"From Megaparsecs to Gigaparsecs: the Clustering of Luminous Red Galaxies and its Cosmological Implications"
The SDSS Photometric Luminous Red Galaxy sample is a complete sample of galaxies from z=0.2 to z=0.6, probing a cosmological volume of 1.5 Gpc3, derived purely from imaging data. I present the first clustering results from this sample, including the detection of clustering on 500 Mpc to 1 Gpc scales and potential evidence of baryonic oscillations in the power spectrum. I will consider the constraints that this measurement places on the current cosmological model, as well as its implications for the role of future imaging surveys, especially in the quest for understanding dark energy.

Oct. 13 (Thursday) 4:10 pm (Astronomy Colloquium)
Andrew Blain , Caltech
2 Le Conte Hall
Properties and environments of ultraluminous high-redshift galaxies
A significant fraction of galaxy formation activity is concealed from view at optical wavelengths by pbscuring dust. I will describe the nature of the population uncovered in this way, its links to more standard populations of high-redshift galaxies, and the prospects for making progress in understanding this population with ALMA and other future instruments.

Oct. 17 (Monday, TAC seminar) 12:10 pm
Tiziana Di Matteo, CMU
544 Campbell Hall
"Black holes and galaxy formation"
Galaxy formation and the growth of supermassive black holes appear to be mutually intertwined processes, to the point that they require joint theoretical modelling to be meaningfully addressed. I will present results of novel hydrodynamical simulations which simultaneously follow star formation black hole accretion, and their associated feedback processes, during major mergers of galaxies. I will discuss black hole growth in the centers of galaxies, their impact on galaxy formation and predictions for quasar lightcurves.

Oct. 18 (Tuesday) 1:10 pm
Ethan Siegel, U Florida
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Effects of Inhomogeneities on Cosmic Expansion"
The accelerated expansion of the universe has no clear-cut theoretical explanation, although many possibilities abound. Recently, there have been considerations that gravitational inhomogeneities on either sub-horizon or super-horizon scales may be the cause of this observed acceleration. In this talk, I will explore and explain the effects of gravitational inhomogeneities on the cosmic expansion rate. The results have been calculated for both linear and fully nonlinear density inhomogeneities. In both regimes, it is found that the net effect of inhomogeneities on the expansion rate is always negligible. Furthermore, inhomogeneity energy never mimics a dark energy component or induces an accelerated expansion.

Oct. 19 (Wednesday lunch/Cosmology talk) 12:10 pm
Dusan Keres, U Mass
544 Campbell Hall (please note room!)
"How do Galaxies get their Gas?"
In SPH simulations the growth of galaxies is dominated by the smooth accretion of gas. About half of the gas enters galaxies through one of two modes: through the conventional "hot accretion mode" where gas is initially heated to the virial temperature in a shock close to the virial radius, as it enters the galaxy halo and than cools to galactic temperatures or through the previously unappreciated "cold accretion mode" where the gas stays cold and until it reaches the galaxy. The cold mode dominates in low mass halos/galaxies and in low galactic number density environments. Overall the cold mode becomes increasingly more important at higher redshifts. Cold mode accretion is very filamentary, while hot mode is quasi-spherical. We also discuss the differences between our findings and the accretion in the semi-analytic models. The galactic mass where the transition between the two modes takes place (2-3 x 10^10M_sun) is close to the transition mass where various galactic properties change rapidly so we speculate a possible connection between the two findings.

Oct. 20 (Thursday) 12:00 noon (not 12:10)
Richard Holman, CMU
LBL 50-5026 (INPA common room)
"Can you see Trans-Planckian Physics in the CMB?"
The WMAP data supports the idea that the primordial fluctuations in the CMB came from quantum fluctuations that were stretched during an inflationary epoch. As these measurements improve, there may be a possibility of measuring effects due to physics beyond the Planck scale. We discuss the viability of this idea and what the signatures of this physics might be.

Oct. 20 (Thursday) 4:00 pm (LBL RPM)
Doug Finkbeiner, Princeton
LBL 50A-5132
"Gamma Rays and Microwaves from Dark Matter Annihilation in the Galactic Center"
Synchrotron emission from a population of ultra-relativistic electrons in the inner Galaxy has been observed by the Wilkinson Microwave Anisotropy Probe (WMAP). After careful modeling of the microwave foreground signals from Galactic interstellar medium a residual microwave signal is present within 10-20 degrees of the Galactic center, uncorrelated with any known foreground template. The most likely explanation for this mysterious component is synchrotron emission from an unusually hot electron energy distribution. The source of these electrons is still uncertain, but the spatial distribution, inferred energy spectrum, and total number are consistent with their being positron-electron pairs produced by WIMP annihilation. These high-energy particles may also produce significant gamma-rays, perhaps already seen by EGRET.

Oct. 24 (Monday, TAC seminar) 12:10 pm
Juna Kollmeier, OSU
544 Campbell Hall
"Multi-Scale Growth of Cosmic Structure"
I will discuss the growth of structure from black holes to the intergalactic medium. Turning density fluctuations into galaxies and black holes is difficult and many outstanding issues remain to be solved. I will discuss three separate ways to attack this problem on different physical scales: IGM-Galaxy correlations on small and large scales, fluorescent Lyman alpha emission from gaseous structures produced in LambdaCDM hydrodynamic simulations, and black hole mass and Eddington ratio measurements with the AGN and Galaxy Evolution Survey.

Oct. 25 (Tuesday) 1:10 pm
Steve Furlanetto, Caltech
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Reionization: The Twilight Zone of Structure Formation"
One of the last frontiers of cosmology is reionization, the hallmark event of the first luminous sources. Recent observations paint a complex picture of this event, implying that the sources and the intergalactic medium interact through a rich set of physical processes. But disentangling these processes requires new windows into this epoch. I will discuss an analytic model for the growth of ionized bubbles during reionization and describe its implications for the process. I will then discuss several potential observational probes of reionization, including quasar absorption lines, Lyman-alpha emitters, and redshifted 21 cm emission, and describe what they can teach us about structure formation in the high-redshift universe.

Oct. 26 (Wednesday lunch/Cosmology talk) 12:10 pm
Michael Kuhlen, UCSC
544 Campbell Hall (please note room!)
"Miniquasar feedback before reionization"
I will present results from recent AMR cosmological hydro simulations modeling the radiative feedback from an early miniquasar. Accreting intermediate mass black holes are powerful sources of X-ray radiation, which is able to penetrate the cold, neutral medium before reionization and significantly alter its thermal and chemical properties. I will discuss the miniquasar's effect on the proto-IGM's temperature, clumping factor, ionization fraction, and molecular hydrogen abundance, and comment on the possibility of observing these effects via redshifted 21cm emission against the CMB.

Oct. 27 (Thursday) 4:10 pm (Astronomy Colloquium)
Timothy Heckman , JHU
2 Le Conte Hall
"The Co-Evolution of Galaxies and Black Holes: The Perspective from the Sloan Digital Sky Survey"

I will summarize a recent investigation into the relation between the evolution of black holes and galaxies on based on SDSS optical spectra of over 400,000 galaxies. We find that the galaxy population exhibits a remarkably simple bimodal behavior in age and structure as a function of stellar mass. Optically-powerful active nuclei (Seyfert nuclei) inhabit those unusual galaxies that are both relatively massive yet have a significant young stellar population. Performing a volume average over the SDSS sample, I will show that the population of black holes with masses less than 100 million M_sun is growing rapidly at the current epoch. The population of more massive black holes ("dead quasars'') is quiescent, with low-level activity traced by low-power radio sources. For massive galaxies as-a-whole, the volume averaged ratio of the rates of star formation to black hole accretion in the present universe is of-order a thousand (similar to the ratio of stellar and black hole mass in galaxy bulges today). The processes that established this ratio in the fossil record are still be at work today.

Oct. 31 (Monday, TAC seminar) 12:10 pm
Eanna Flanagan, Cornell
544 Campbell Hall
"Theoretical Explanations for the Accelerating Universe"
I survey some of the microphysical models for the observed acceleration of the Universe, including models involving dark energy in the form of a scalar field, and models involving modifications of general relativity at large lengthscales, and a continum of models interpolating between these two possibilities. Several proposed models can be ruled out using astrophysical or laboratory constraints, while others suffer from severe naturalness problems. I also discuss and argue against recent proposals that the observed acceleration can be explained without recourse to new physics, using only the nonlinearities of general relativity.

September 2005:

Sep. 6 (Tuesday) 1:10 pm
Brant Robertson, Harvard/CfA
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"The Fundamental Scaling Relations of Elliptical Galaxies"
Using hydrodynamical simulations of merging galaxies including star formation, supernovae feedback, and a new prescription for supermassive black hole growth and feedback, we explore possible origins for the fundamental scaling relations of elliptical galaxies. We find that the black hole mass - stellar velocity dispersion ("M-sigma") relation generated by the merging of gas-rich disk galaxies obtains the same power-law scaling independent of redshift between z=0-6. Similarly, the Fundamental Plane relation for elliptical galaxies produced by gas-rich disk mergers obtains the same scaling between redshifts z=0-6. We connect the tilt of the Fundamental Plane to the stellar phase- space density of the remnants and show that gas dissipation may produce the Fundamental Plane tilt observed in the near-infrared where stellar population effects are likely unimportant. Finally, we show that the re-merging of spheroidal galaxies maintains both the M-sigma and Fundamental Plane relations in accordance with the small scatter observed in each relation for local galaxies.

Sep. 8 (Thursday) 4:10 pm (Astronomy Colloquium)
Jerry Ostriker , Princeton
2 Le Conte Hall
Cosmic Star Formation: A Problem for the Hierarchical Model?
First, we will note that there are three completely independent ways of determining the cosmic history of star-formation: (1) direct observation of the past light-cone using large optical/IR telecopes; (2) pure thought - ie numerical simulations based on the standard LCDM model; and (3) reconstruction of the past, based on the fossil (z ~ 0) evidence from the local SDSS-observed universe. These agree. And more detailed analysis shows that bright, massive red galaxies are in fact expected to exist at relatively high red-shifts in the standard cosmological model.

Sep. 13 (Tuesday) 1:10 pm
Ted Baltz, Stanford/SLAC
544 Campbell Hall (also videoconferenced to LBL 50-5131)
""Lensing probes of dark baryons and dark matter"
Gravitational lensing probes the matter content of the universe directly, without the bias of mass-to-light ratio. A wide variety of lensing techniques can be brought to bear to study dark matter (and dark baryons) directly. First: gravitational microlensing is a powerful tool for studying dark stellar-mass objects, including stellar remnants and even primordial black holes. It is known that roughly half of the baryons are missing in the local universe. These may reside in stellar remnants accessible to microlensing surveys and / or in a warm-hot intergalactic medium (WHIM). We discuss such surveys of the local group, local supercluster, and beyond. Second: strong lensing by galaxies and clusters, producing multiple images of background objects, directly probes the matter distribution (radial and tangential) of the lenses. We discuss preliminary work toward studying rare lens configurations that may appear in large samples of lenses. Such chance alignments are quite sensitive to the structure of the lenses, and may allow more detailed measurements of their properties.

Sep. 16 (Friday) 12 noon (special Physics talk)
Jiun-Huei Proty Wu , National Taiwan University
468 Birge
CMB Constraints on Cosmic Defects, Inflation, String theory, SUSY GUT, and AMiBA
In the last decade, new observation technology has brought us to an entirely new regime in cosmology and astrophysics. In this talk, we will introduce a new approach that transforms the CMB observational results to realistic constraints on some fundamental physics, such as Inflation, String theory, and SUSY GUT. A possible common byproduct of these theories is the cosmic defects. Based on a newly devised technique, we performed a maximum-likelihood analysis using the WMAP data to show that the power fraction of any type of defects at the first peak in the CMB power spectrum is persistently less than 4.5% at the 68% confidence. In turn this result was transformed to constraints on, for example, the superstring scale in String theory, the mass scale, gauge coupling, and superpotential coupling in SUSY GUTs, etc. Our approach and results are insensitive to the uncertainties in the theoretical predictions for defect models, and thus the most robust to date. At the end, we will briefly describe the current status of the Taiwanese CMB project, AMiBA, which is now being assembled on Mauna Loa at the Big Island.

Sep. 20 (Tuesday) 1:10 pm
Rachel Mandelbaum, Princeton
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"Science results with SDSS weak lensing"
The SDSS has proven to be an excellent dataset for exploring various problems in astrophysics and cosmology using weak lensing, with the highest lensing signal to noise to date and spectroscopic redshifts for lens galaxies, which simplifies theoretical interpretation by allowing us to compute signal as a function of transverse separation rather than angle. In this talk, I will describe our new Reglens reduction method that is used to measure galaxy shapes, discuss constraints on systematic errors, and describe several interesting science results that have resulted from it. Recently, we have placed constraints on dark matter halo ellipticity, and detected intrinsic ellipticity-density alignments that may be important contaminants of current and future weak lensing surveys. I will also describe ongoing work such as a measurement of the dark matter power spectrum using a combination of galaxy-shear cross-correlation and galaxy-galaxy autocorrelation techniques; a study of the relationship between stellar masses, luminosities, and dark matter halo masses as a function of morphology and local environment; and the determination of average halo profiles using the lensing signal around field galaxies.

Sep. 22 (Thursday) 4:10 pm (Astronomy Colloquium)
Xiaohui Fan, Arizona
2 Le Conte Hall
High Redshift Quasars and the End of Reionization
During the last five years, the Sloan Digital Sky Survey has discovered 19 quasars at z>5.7. These quasars provide powerful probes to the accretion history of early black holes and to history of reionization. I will discuss the evolution of quasar luminosity function, mass function and chemical enrichment at z~6 using these quasars. Then I will discuss using these qusars to study IGM evolution at the end of reionization: we observe strong and accelerated evolution of IGM neutral fraction, accompanied by an increased line of sight variation, indicating that the universe might be entering overlap stage of reionization at slightly higher redshift.

Sep. 26 (Monday) 2:10 pm
Naoki Itoh , Sophia University
468 Birge
"Relativistic Corrections to the Sunyaev-Zel'dovich Effect for Clusters of Galaxies"
High-temperature plasmas exist inside the clusters of galaxies. The temperature is generally 5-15 keV. These high temperature electrons interact with the 2.726K cosmic microwave photons and distort the Planck spectrum. This is the well-known Sunyaev-Zel'dovich effect. This has been successfully carried out recently by our group as well as some other groups. In this talk I will discuss the importance of the relativistic corrections. In fact they will be extremely important for the forthcoming short-wavelength observations of the Sunyaev-Zel'dovich effect.

Sep. 27 (Tuesday) 1:10 pm
Elena Pierpaoli, CalTech
544 Campbell Hall (also videoconferenced to LBL 50-5131)
"A new era for galaxy clusters
Clusters of galaxies, as observed in the optical and X-rays, have extensively been used to constrain cosmology. Current and future CMB experiment in the radio and infrared bands will observe clusters in a novel way, potentially discovering several new ones. I will discuss how these new observations can be exploited to better understand cluster physics and derive cosmological paramenters.
Sep. 29 (Thursday) 4:00 pm (RPM at LBL)
Daniel Eisenstein, Arizona
LBNL 50A-5132
Dark Energy and Cosmic Sound

August 2005:

Aug. 2 (Tuesday) 1:10 pm
Michele Cappellari, Leiden
544 Campbell Hall
"Dynamics of nearby galaxies and the origin of the Fundamental Plane"
We construct accurate dynamical models of a sample of 25 early-type galaxies, for which SAURON integral-field kinematical observations exist. We provide a first detailed view of the internal orbital distribution in galaxies, fossil record of their formation process. We revisit the interpretation of the V/sigma anisotropy diagram, and we set tight constraints on the origin of the Fundamental Plane of early-type galaxies.

Aug. 3 (Wednesday, joint Cosmology/Wed. lunch talk)
12:10 pm, please note time and room change!
Eric Gawiser, Yale
501 Campbell Hall
"The MUSYC Census of Protogalaxies at z=3"
Despite recent advances in the study of galaxy formation, the progenitors of typical galaxies like the Milky Way have yet to be identified. The Multiwavelength Survey by Yale-Chile (MUSYC) is investigating the star formation rate, stellar mass, and dark matter halo mass of high-redshift protogalaxies in order to separate physical properties from selection effects. These protogalaxies include Lyman break galaxies, Lyman alpha emitters, Damped Lyman alpha absorption systems, evolved optical-break galaxies, and AGN. I will present initial results, including public UBVRIz images and catalogs of the 33'x34' Extended HDF-S available from, spectroscopic redshifts obtained with Magellan-IMACS, and determinations of the Lyman alpha emitter and Lyman break galaxy correlation functions at z=3.

Aug. 9 (Tuesday) 1:10 pm
Hans-Walter Rix,
544 Campbell Hall
"The formation and evolution of massive galaxies"

Aug. 15 (Monday, TAC seminar) 12:10 pm
Frank van den Bosch, ETH-Zurich
544 Campbell Hall
"The Galaxy-Dark Matter Connection"
I present a new statistical method to link galaxies to their dark matter haloes. I show how the galaxy-dark matter connection thus established can be used to (i) constrain both galaxy formation and cosmology and (ii) construct detailed mock galaxy redshift surveys. In particular, I show how pairwise peculiar velocity dispersions and cluster mass-to-light ratios require a relatively low value for the power-spectrum normalization parameter, sigma_8, and demonstrate that there are two characteristic scales in galaxy formation. I also present results from large catalogues of galaxy groups selected from the 2dFGRS and SDSS with a new, halo-based group finder. In will use these to argue that, contrary to common wisdom, galaxy properties do not depend on environment or luminosity, but only on the mass of the halo in which they reside.

Aug. 16 (Tuesday RAL talk) 1:10 pm
Reinhard Genzel, UCB and MPE
544 Campbell Hall
"Recent results from the home of black holes and massive stars"

July 2005:

July 20 ( Wednesday) 12:10 pm
Guinevere Kauffmann, Garching
544 Campbell Hall
"Gas infall and Stochastic Star Formation in Galaxies in the Local Universe"

July 25 ( Monday) 12:10 pm
Alexandre Amblard and Tzu-Ching Chang, Berkeley
501 Campbell Hall
Report from Reionizing the Universe meeting in Groningen

July 27 ( Wednesday) 12:10 pm
Simon White, Garching
544 or 501 Campbell Hall (tbd)
Informal Update

June 2005:

June 13-17 all day
LBL Cosmology Summer Visitor Program: Cosmology with the Ly-alpha Forest
Note: this will be mostly intensive discussion sessions, rather than formal talks.

Past Cosmology Seminars in 2004-2005 Academic Year

Past Cosmology Seminars in 2003-2004 Academic Year

Past Cosmology Seminars in 2002-2003 Academic Year

Past Cosmology Seminars in 2001-2002 Academic Year

Website Menu: [ Home | Education/FAQ | Directory | Research | Links | About us ]