INPA

Special - Danielle Leonard (CMU) - Measuring the scale-dependence of intrinsic alignments using multiple shear estimates
2018-02-12 12:00 - 13:00 (America/Los_Angeles) | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The next generation of cosmological surveys promises significant advancements in the field of weak gravitational lensing. As such, it is crucial that relevant systematic effects such as the intrinsic alignment of galaxies are well-understood. I will discuss a new method for measuring the scale-dependence of the intrinsic alignment contamination to the galaxy-galaxy lensing signal, which takes advantage of multiple shear estimates applied to the same data set. For a galaxy-galaxy lensing measurement which uses LSST sources and DESI lenses, the signal-to-noise on the intrinsic alignment signal measured by our method is forecast to improve on an existing method (Blazek et al. 2012) by a factor of >2, for optimally chosen pairs of shear estimates.

Wing Yan Ma (Imperial College London) - Recent Neutrino Oscillation Results from T2K
2018-02-09 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
T2K is a long baseline neutrino experiment situated in Japan. A muon neutrinos and antineutrinos beam is produced and fired 295km across the country and observed using the 50 kTon Super Kamiokande detector. By studying how many of these neutrinos have oscillated into different flavours and whether the oscillations occur differently for antineutrinos we have sensitivity to CP violation in the neutrino sector. I will present the latest results of the neutrino oscillation measurements using data collected up to May 2017, including new limits on the CP violating parameter δCP.

Jason Bono (Fermilab) - Muon Anomalies and Their Future Investigations
2018-02-02 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The muon is 200 times heavier than the electron and still lighter than any hadron, which make it’s interactions, at once, potentially sensitive to undiscovered phenomena, and predictable to high precision within the Standard Model. The muon’s ease of production, natural polarization and self analyzing decay, and comparatively long lifetime also allow for extremely high precision measurements of fundamental constants and interactions. Muons thus offer a unique probe to search for physics beyond the Standard Model.
This discussion will first elaborate on some of the experimental and theoretical niceties of the muon, and briefly look at the particle from a historical perspective, emphasizing a few of the many important roles that it’s played in piecing together our current understanding of particle physics. We will then look at a variety of anomalies in experiments using muons, which, taken together may suggest the possibility of sensitivity to new physics within reach of future experiments, some of which will also be looked at. Topics include recent developments in the proton radius puzzle, the muon anomalous magnetic moment, hints of lepton flavor non-universality in B decays, and searches for charged lepton flavor violation. For fun, a recent discovery in the Great Pyramid of Giza using muon tomography will also be discussed.

Elizabeth Wills (Drexel) - Probing Cosmic Ray Anisotropy in the Northern Hemisphere with Atmospheric Neutrinos
2018-01-26 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Cosmic Rays have remained an enigma for over a hundred years since their discovery. This talk focuses on a well-measured, yet similarly elusive feature; an unexplained structure in arrival direction spanning many energies and angular scales. This talk introduces a new way of exploring Cosmic Ray Anisotropy: observation through secondary neutrinos. Studying the cosmic rays’ neutral daughter particles with pointing capabilities, like neutrinos, could shed new light. This can be done at two levels; a source which produces cosmic rays must also produce high energy astrophysical neutrinos, and low energy atmospheric neutrinos are made when the cosmic rays interact with the atmosphere. This analysis focuses on atmospheric neutrinos detected by IceCube, a Cherenkov detector instrumenting a kilometer cubed of glacial ice at the South Pole. IceCube has studied the anisotropy and its energy dependence in the Southern sky using atmospheric muons.

Using IceCube and a high-acceptance dataset of atmospheric neutrinos created for this analysis, we are nearing the sensitivity threshold to observe the phenomenon in atmospheric neutrinos arriving from the Northern Hemisphere. This analysis focuses on energy ranges that correspond to the spatially-consistent lower energy features of the dipole structure. Due to the statistical limitations of the neutrino dataset in comparison to the cosmic ray datasets, we also introduce new methods for detecting signal along with the standard multipole analysis methods. These include a 1D relative intensity fit to determine the amplitude and phase of the dipole, and a 2D binned log-likelihood analysis focusing on searching for observed anisotropy maps from the Tibet collaboration. Future hope for the work is to create a single-detector all-sky map of the anisotropy, minimizing systematical difficulties combining datasets from separate collaborations.

Bjoern Lehnert (Carleton University) - Dark Matter Search with DEAP-3600 and the Importance of Rare Nuclear Decay Searches
2018-01-23 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The DEAP-3600 experiment is searching for dark matter with a single phase liquid argon (LAr) target, located at SNOLAB. For a background-free exposure of 3000 kg·yr, the projected sensitivity to the spin-independent WIMP-nucleon cross section at 100 GeV/c2 WIMP mass is 1e-46 cm2. The construction and filling of DEAP-3600 was completed in 2016 and the experiment is currently taken physics data. Recently, the first results of an initial commissioning data set were presented which could successfully demonstrate the detector performance and resulted in the leading limit on the WIMP-nucleon spin-independent cross section for argon.
In the first part of this seminar I will present the DEAP-3600 experiment and its recent results with an emphasis on radioactive backgrounds. In the second part of the seminar I will briefly describe a few recent investigations of rare beta and double beta decay processes such as 36Ar, 39Ar and 42Ar with DEAP but also other isotopes with gamma-spectroscopy setups. I will illustrate their importance in the context of radioactive backgrounds in other low background experiments and in the context of understanding nuclear structure. Especially the better understanding of nuclear models and their intrinsic parameters is needed to obtain more reliable nuclear matrix elements e.g. for neutrinoless double beta decay processes in order to connect the observed half-life to the the effective Majorana neutrino mass.

Hirotaka Ito - Numerical Simulations of Photospheric Emission from Collapsar Jets
2018-01-12 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
We explore the photospheric emission from a relativistic jet breaking out
from a massive stellar envelope based on relativistic hydrodynamical simulations and post- process radiation transfer calculations in three dimensions. It is shown that structures developed within the jet during its propagation have a significant imprint on the resulting emission. Particularly, we show that the viewing angle dependence of the emission properties caused by the lateral structure naturally reproduces the observed correlation between the peak energy and luminosity (Yonetoku relation). We also show that the emission possesses non-negligible degree of polarization.

Marco Salathe (LBL) - GRETA R&D
2017-12-15 12:00 - 13:00

Anna Zsigmond - GERDA neutrinoless double beta decay experiment
2017-12-08 08:00 - 17:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA

Yuan Mei (LBL) - TPC without charge multiplication: a CMOS direct readout towards neutrinoless double-beta decay and other applications
2017-12-01 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
High-pressure gaseous TPCs provide a unique combination of excellent energy resolution, event tracking for background discrimination, and scalability, which are ideal for neutrinoless double-beta decay searches. We are developing a pixelated charge readout plane filled with an array of CMOS sensors to harness the power of such a TPC. Each CMOS sensor has an exposed metal patch for direct charge collection and integrates charge sensitive amplifiers as well as signal processing and digitization/data transmission circuitry. The electronic noise is suppressed to a level that the required signal-to-noise ratio is achieved without the need of charge multiplication. It provides competitive energy resolution while improves on tracking capability, stability, and scalability compared to alternative readout schemes. Moreover, ions drifting in the gas can be read directly since the otherwise prohibitive ion avalanche is unnecessary. It enables the use of alternative gases and double-beta decay candidate isotopes such as $^{82}$SeF$_6$ gas, in which only ion drifting is possible. With modest modifications, the readout plane could be used in liquid noble gas and organic liquid TPCs for a broad range of applications. The design and the progress of the first prototype will be presented.

Holiday
2017-11-24 08:00 - 17:00

Katelin Schutz (UCB) - Excluding a thin dark matter disk in the Milky Way with Gaia DR1: Resurrecting the Dinosaurs
2017-11-10 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
If a component of the dark matter has dissipative interactions, it could collapse to form a thin dark disk in our Galaxy coincident with the baryonic disk. It has been suggested that dark disks could explain a variety of observed phenomena, including mass extinction events due to periodic comet impacts. Using the first data release from the Gaia space observatory, I will present the results of a search for a dark disk via its effect on stellar kinematics in the Milky Way. I will discuss our strong new limits that disfavor the presence of a thin dark matter disk and present updated measurements on the total matter density in the solar neighborhood.

Noah Kurinsky (Stanford) - Pushing to Low Mass with SuperCDMS SNOLAB: New Developments in Ultra-Low Threshold Dark Matter Detectors
2017-11-03 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
In the last few years, the dark matter field has bifurcated into experiments focused on wimp-scale dark matter with massive liquid noble detectors and experiments focused on so-called ‘hidden sectors’ dark matter, pushing small detectors to much lower energy resolutions. Low-mass dark matter searches, focusing on single eV-scale energy deposits, are sensitive to different backgrounds than their higher-threshold counterparts, including but not limited to infrared emissions from the experimental environment and low-rate cosmogenic contamination in the target materials. The traditional paradigm of 2-phase detectors used to discriminate between electronic and nuclear recoils is no longer effective, both because of experimental limitations and kinematic constraints. The low-mass reach of SuperCDMS SNOLAB is based on the idea of moving from a phonon+charge readout to a charge-mediated phonon readout; introducing degeneracy between our separate detection channels to achieve lower thresholds. In this talk I will discuss the theory behind the CDMS-HV detector technology and present exciting results from prototype detectors run at test facilities in the CDMS collaboration. I will then discuss the science reach given these results, and explore future directions with this technology.I will describe our development of a convolutional neural network (CNN) to learn to search for and characterize absorption lines in quasar spectra. Specifically, the algorithm discovers and measures the redshift and Hydrogen column density of damped Lya systems (DLAs). These systems dominate the neutral hydrogen gas of the universe, trace the interstellar medium of distant galaxies, and offer cosmological constraints on the build up of gas and heavy elements across cosmic time. I will discuss the lessons learned employing CNN techniques on large spectral datasets and the prospects for future analysis.

Xavier Prochaska (UCSD) - Deep Learning of Quasar Spectra
2017-10-27 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
I will describe our development of a convolutional neural network (CNN) to learn to search for and characterize absorption lines in quasar spectra. Specifically, the algorithm discovers and measures the redshift and Hydrogen column density of damped Lya systems (DLAs). These systems dominate the neutral hydrogen gas of the universe, trace the interstellar medium of distant galaxies, and offer cosmological constraints on the build up of gas and heavy elements across cosmic time. I will discuss the lessons learned employing CNN techniques on large spectral datasets and the prospects for future analysis.

Prabhat (NERSC at LBL) - Deep Learning for Science
2017-10-20 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Deep Learning has revolutionized the fields of computer vision, speech recognition and control systems. Can Deep Learning (DL) work for scientific problems? This talk will explore a variety of DOE/LBL applications that are currently benefiting from Deep Learning. We will review classification and regression problems in astronomy, cosmology, neuroscience, genomics and high-energy physics. We will outline several short and long-term challenges at the frontier of DL research, and speculate about the future of DL for data-intensive science.

Michael Walther (UCSB) - New Constraints on Thermal Evolution in the IGM from the Small Scale Lyα Forest Power Spectrum
2017-10-13 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The line-of-sight power spectrum (P_F(k)) of the Ly-α forest has proven to be a valuable tool for doing cosmological observations. It also not only allows to constrain cosmological parameters, but enables us to measure the thermal state of the IGM at redshifts z>1.8. While at large scales (k<0.02 s/km) P_F(k) has been accurately measured using the large number (10^3-10^5) of quasar sightlines from SDSS and BOSS, there are much less spectra available at smaller scales (larger k). Prior power spectrum measurements from high-resolution data only used several times less (QSO) spectra in our redshift range about 15 years ago whereas a few hundred became available in the meantime. We therefore performed a new measurement using 74 quasar sightlines with 1.8<z<3.4 significantly improving the precision of the small-scale P_F(k). Using this additional precision on small scales combined with the BOSS measurements on large scales enables us to accurately constrain the thermal cutoff scale of the IGM set by a combination of temperature broadening of Ly-α forest lines, and ‘Jeans’ smoothing due to baryonic pressure support. We perform an MCMC analysis based on Gaussian process based techniques for interpolation between a grid of high-resolution hydrodynamical simulations and using our new high-resolution dataset, the BOSS data, a recent X-SHOOTER analysis, and a previous HIRES/MIKE analysis at higher redshifts. This allows us to measure thermal evolution in the IGM from z=5.4 to z=1.8 showing a suggestive peak at z~3.3 that might be attributed to He reionization. These constraints will help solving the existing discrepancies in the IGM thermal evolution between different works using different techniques as existing degeneracies between different thermal parameters in the existing measurements can be broken in our analysis.and can be used to place limits on possible exotic sources of heating. Additionally a better knowledge of thermal evolution will also lead to better constraints of e.g. the nature of dark matter or neutrino masses by breaking degeneracies in those measurements and thereby improve our knowledge of the underlying cosmology.

Marie Lau (UC Santa Cruz) - Quasars Probing Quasars: the Circumgalactic Medium Surrounding z ~ 2 Quasars
2017-10-06 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Understanding the circumgalactic medium–the gaseous halo surrounding a galaxy, is an integral part to understanding galaxy evolution. The z ~ 2-3 universe is interesting as this is when the star formation rate and AGN activity peak. My work concludes the decade-long Quasars Probing Quasars survey designed for studying massive galaxy formation and quasar feedback. I use background quasar sightlines that pass close to foreground quasars to study the circumgalactic medium of quasar-host galaxies in absorption. My sample of 149 quasar pairs involve spectra taken with 17 different optical and near IR instruments. I present results on the statistical and physical properties of the quasar circumgalactic medium. My results pose challenges for cosmological hydrodynamic simulations to produce a substantial cool gas reservoir surrounding quasars, that is also enriched and exhibits extreme kinematics.

I will discuss other science goals that can be facilitated using the spectral databases and absorption-line analysis tools built. If there is interest, I will show preliminary results on a peculiar tidal disruption event and evidence for deep internal mixing in red giants.

Stephen Portillo (Harvard) - Improved Source Detection in Crowded Fields using Probabilistic Cataloging
2017-09-29 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Cataloging is challenging in crowded fields because sources are extremely covariant with their neighbors and blending makes even the number of sources ambiguous. We present the first optical probabilistic stellar catalog, cataloging a crowded (~0.1 sources per pixel) Sloan Digital Sky Survey r band image from M2. Probabilistic cataloging returns an ensemble of catalogs inferred from the image and thus can capture source-source covariance and deblending ambiguities. By comparing to a traditional catalog of the same image and a Hubble Space Telescope catalog of the same region, we show that our catalog ensemble better recovers sources from the image. It goes more than a magnitude deeper than the traditional catalog while having a lower false discovery rate brighter than 20th magnitude. Future telescopes will be more sensitive, and thus more of their images will be crowded. We detail our efforts to extend probabilistic cataloging to galaxies, making the method applicable to the data that will be collected in the Large Synoptic Survey Telescope era.

Yury Kolomensky (LBNL) - New results from the CUORE experiment
2017-09-22 12:00 - 13:00

Oliver Just (RIKEN)​ - Modeling remnants of neutron-star mergers and core-collapse supernovae
2017-09-15 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Neutron-star mergers and core-collapse supernovae are promising events to herald a new era of multi-messenger astronomy, as they release substantial amounts of energy in gravitational waves, neutrinos, and electromagnetic emission. Moreover, these events are connected to long-standing physics questions related to, e.g., heavy-element nucleosynthesis, gamma-ray bursts, and the nuclear equation of state. However, while offering a unique laboratory to investigate matter and spacetime under extreme conditions, these events are particularly difficult to model theoretically, one of the most challenging, but equally important ingredients being the neutrino transport. The latter is not only responsible for cooling the compact remnant and heating its surroundings, but it may also have a major leverage on the nucleosynthesis conditions in the ejecta and the eventual launch of a polar jet. In this talk I will review the current state-of-the-art in modeling mergers and core-collapse supernovae and present some recent results that we obtained from numerical simulations.

Yi-Kuan Chiang (Johns Hopkins) - Which Galactic dust map should I use? Insights from extragalactic tomography
2017-08-04 12:00 - 13:00 | INPA Common Room, 50-5026
Over the past few years, clustering-based redshift estimation has emerged as a new way to estimate redshifts and perform extragalactic tomography of arbitrary datasets. On a similar timescale, observations by Planck, WISE, Pan-STARRS and 21cm radio surveys have been used to create a multitude of SFD-type Galactic dust maps. I will explain how clustering-based redshift estimation can be used to test the quality of the seven different dust maps currently available and I will show that extragalactic signatures can be revealed in many of them. When such maps are used for correcting optical magnitudes, we therefore expect biases which are likely to affect the precision of cosmological experiments using supernovae, BAOs, or the growth of structures. I will present possible solutions to alleviate this issue and discuss which map should be used depending on which measurement one wishes to make.

Eddie Schlafly (LBNL) - Mapping the Galaxy's Dust in 3D
2017-06-30 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
The Milky Way’s dust is of basic importance in astronomy. It
is both crucial to the formation of stars and is a pervasive
observational nuisance. Despite the dust’s importance, existing dust
maps are largely limited to two dimensions, with the distance to the
dust unknown. The advent of large surveys like Pan-STARRS1 has
allowed us to map dust in three dimensions in unprecedented detail. In
this talk, I will describe how we use observations of stars in the
Milky Way to map dust, and I will discuss three major results: a
catalog of distances to major molecular clouds, the discovery of a 100
pc ring of dust in Orion, and the 3D dust map itself. Upcoming
surveys promise continued scientific returns: Gaia, DECam, and LSST
will provide more precise and deeper data than ever before, enabling
unique maps of the Galaxy’s spiral structure and the study of the
dust’s properties in 3D.

Samuel Hinton - Bayesian Hierarchical Methods for Supernova Cosmology
2017-06-23 12:00 - 13:00
In the era of precision cosmology, systematic uncertainty is quickly becoming the limiting factor in modern cosmological analyses. In my work, I discuss a method for performing supernova analyses by combining a hierarchical Bayesian framework with Monte-Carlo simulation realisations. This gains both the flexibility and speed of an analytic analysis along with the nuance and complexity of an algorithmic analysis, allowing for a deeper and more complex analysis.

Giovanni Benato (LBNL) - Discovery probability of next-generation neutrinoless double-β decay experiments
2017-06-09 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Neutrinoless double beta (0νββ) decay is the only process which can feasibly investigate the
Majorana nature of neutrinos and total lepton number conservation.
A broad international experimental program requiring considerable resources is being mounted to search for 0νββ decay in the region of parameter space allowed for Inverted Ordering.
The Bayesian discovery probability of future experiments searching for 0νββ decay is evaluated.
A Bayesian global fit is performed to construct a probability distribution for the effective Majorana mass, the observable of interest for these experiments. This probability distribution is then combined with the sensitivity of each experiment derived from a heuristic counting analysis. The discovery probability strongly depends on whether the neutrino mass ordering is normal or inverted, and is found to be higher than previously considered for both mass orderings. In the absence of neutrino mass mechanisms that drive the lightest state or the effective Majorana mass to zero, for the inverted ordering next-generation experiments are likely to observe a signal already during their first operational stages. Even for the normal ordering, the probability of discovering neutrinoless double-β decay reaches ∼50% or more in the most promising experiments.

Jose Ezquiaga (UAM) - Testing dark energy and gravity with the speed of gravitational waves
2017-06-02 12:00 - 13:00
LIGO’s gravitational waves (GWs) detection has inaugurated an era to test the foundations of gravity. This includes also probing the nature of Dark Energy. Theories explaining the present acceleration of the Universe beyond the cosmological constant typically require adding extra gravitational degrees of freedom. This can lead to distinct signatures in the propagation of GWs. I will review current tests of gravity over different scales and regimes, and examine different frameworks describing dynamical dark energy. Then, focusing on the case of only one additional degree of freedom, I will present how the speed of GWs could be used to place severe constraints on generic scalar-tensor theories of gravity. I will describe under which circumstances an anomalous propagation speed can arise, and how it could be measured in the near future. If there is a small deviation from the speed of light, the delay between the GW and any electromagnetic counterpart will run beyond human time scales. Still, this measurement could be achieved with LISA using eclipsing white dwarf binaries. This test will either eliminate many contender models for cosmic acceleration or wreck a fundamental pillar of general relativity.

Titouan Lazeyras (MPA) - Dark matter halo bias from separate universe sim-ulations
2017-05-26 12:00 - 13:00
The large-scale local bias parameters of dark matter halos are essential to
describe the statistics of halos and galaxies on large scales, as well as for
the halo model of the matter distribution. Using so-called separate universe
simulations, we recently obtained precise measurements of the three leading
bias parameters. For b2 and b3, these are the most precise measurements
to date. We compare our results with bias parameters obtained from two
and three points cross-correlation functions and with theoretical predictions
from the excursion set peaks (ESP) model.
Using the same set of simulations, we further investigate halo assembly bias,
i.e. the dependence of the halo bias on properties other than the halo mass.
We focus on four halo properties : halo concentration, spin, ellipticity and
mass accretion rate. We measure assembly bias for b1 and nd good agree-
ment with previous studies. Furthermore, we present results for assembly
bias in b2 which are among the rst ones and most precise to date. To try
and better understand the physical mechanisms behind assembly bias, we
also look at the joint dependence of bias on two halo properties in addition
to the mass.

Jon Ouellet (MIT) - ABRACADABRA: A New Approach to the Search for Axion Dark Matter
2017-05-19 12:00 - 13:00
The evidence for the existence of Dark Matter is well supported by
many cosmological observations. But we have not yet been able to
determine how this new type of matter fits into our understanding of
the Universe on the smallest scales. Separately, long standing
problems within the Standard Model point to new weakly interacting
particles to help explain away unnatural fine-tunings. The axion was
originally proposed to explain the Strong-CP problem, but was
subsequently shown to be a strong candidate for explaining the Dark
Matter abundance of the Universe. ABRACADABRA is a proposed
experiment to search for ultralight axion Dark Matter, with a focus on
the mass range $10^{-14} lesssim m_a lesssim 10^{-6}$\,eV. We search
for these axions and other axion like particles (ALPs) through a
modification to Maxwell’s equations, which cause strong magnetic
fields to source weak oscillating electrical currents parallel to the
field. These weak currents can be detected through the magnetic fields
that they generate. To see these, ABRACADABRA will use highly
sensitive SQUID magnetometers in a very low noise environment. At
MIT, we are building a 10\,cm scale prototype that will quickly be
sensitive to untested regions of parameter space. In the long term, we
hope to scale ABRACADABRA to a 1\,m$^3$ scale detector, which could be
sensitive enough to probe the QCD axion scale.

Jessica Lu (UCB) - New Developments in Adaptive Optics: Wide Fields and Precise PSFs
2017-05-12 12:00 - 13:00
Adaptive optics correct for the blurring effects of the Earth’s atmosphere. However, most AO systems today suffer from limited fields of view and point spread functions that vary over time and position. I will present results from several experiments to overcome these limitations. We have deployed a ground-layer adaptive optics experiment on the UH 2.2 m telescope on Maunakea to test the AO image quality over fields of view as large as 20 arcminutes. This experiment is a key first step in understanding whether a GLAO system would be feasible for other 8-10 m telescopes equipped with wide-field multi-object spectrographs. We are currently investigating the science feasibility of such a system for Keck. I will also present our efforts to reconstruct the AO point spread function and deliver more precise scientific measurements from Keck’s narrow-field AO system. Initial science applications include close binaries, quasar host galaxies, and the Galactic Center. Future cases include strongly lensed galaxies and supernovae, black hole hunting with astrometric microlensing, and direct imaging of exoplanets.

Daniel Dwyer (LBNL) - Evidence against sterile neutrinos from the Daya Bay Experiment
2017-05-05 12:00 - 13:00 | 50A-5132- Sessler, 50A-5132 Sessler Conference Room, CA
Prevailing models of antineutrino emission by nuclear reactors do not
agree with observations. This discrepancy has been considered
possible evidence for neutrino oscillation to non-interacting, or
sterile, neutrino states. Although the existence of sterile neutrinos
would have profound implications, a variety of measurements by the
Daya Bay Experiment disfavor sterile models. I will summarize these
observations with a particular focus on the latest result: a precise
measurement of the antineutrino flux versus reactor fuel burn-up.
I’ll wrap up with a provocative question: does any compelling evidence
for sterile neutrinos remain?

Javier Caravaca Rodriguez (UCB) - Cherenkov and Scintillation light separation with the CHESS experiment
2017-04-28 12:00 - 13:00
The first step toward construction of a hybrid optical detector like THEIA is the demonstration of separation of scintillation and Cherenkov light in liquid scintillators (LS). This would allow reconstruction of particle directionality in a low energy threshold detector, and provide improved particle identification. The CHESS experiment successfully images Cherenkov rings on LS such as LAB and LAB with PPO, demonstrating this separation. Despite the relatively high light yield of the scintillation light with respect to the Cherenkov light, the latter is successfully identified thanks to the characteristic prompt emission time of a few picoseconds, as oppose to the typical nanoseconds delays of the scintillation emission. Low time jitter PMTs ($sim300ps$) and fast digitization ($5GHz$) provides a precision well below the nanosecond level, making the time separation possible. Recent results obtained with pure LS and preliminary studies for newly developed water-based LS materials will be presented.

Ken Chen (NAOJ) - Lighting up the Universe with Extreme Supernovae
2017-04-21 12:00 - 13:00
Recent all-sky transient searches have discovered new and unexpected explosion types that fall outside traditional SN classification schemes. These exotic outliers in many cases are due to the deaths of massive stars and therefore may have been prevalent in the primordial universe because the Pop III IMF is thought to be top-heavy. Depending on the mass of the progenitor, these outliers may be faint, magnetar-powered, pair-instability, or general relativistic instability SNe, all of which have unique observational signatures. Some of these events are superluminous, 10-100 times brighter than normal supernovae, and may produce energetic UV, X-ray, or gamma-ray bursts. Their extreme luminosities enable their detection at z > 10 and they are ideal probes of the primordial universe at cosmic dawn, prior to the advent of the first galaxies. Here, we examine these exotic explosions with state of the art 3D radiation-hydro simulations that bridge all spatial scales from the central engine to breakout into the IGM, where observational signatures can be computed. We discuss the coevolution of radiation and turbulent mixing in SN ejecta and present realistic light curves for these explosions for JWST and the coming generation of extremely large telescopes (ELTs). Detection rates for Pop III SNe can place useful constraints on the primordial IMF, and their nucleosynthetic yields can be used to study the chemical compositions of extreme metal poor stars.
