"Fermi Large Area Telescope and its recent results on Active Galactic Nuclei"

Elisabetta Cavazzuti

GSFC

Tuesday, Jan 23, 2018

Abstract

The Fermi Gamma-ray Space Telescope has operated for more than 9 years and provided unprecedented information about many source classes, including Active Galactic Nuclei. I will review the most recent results and milestones concerning this apparently well-known source class. Although these broad-band, bright objects are extensively studied across the entire electromagnetic spectrum, we still do not understand their intrinsic nature, and new paradigms are being explored.

"Cosmology with the HSC Survey"

Rachel Mandelbaum

CMU

Tuesday, Jan 30, 2018

Abstract

Hyper Suprime-Cam (HSC) is an imaging camera mounted at the Prime Focus of the Subaru 8.2-m telescope operated by the National Astronomical Observatory of Japan on the summit of Mauna Kea in Hawaii. A consortium of astronomers from Japan, Taiwan and Princeton University is carrying out a three-layer, 300-night, multiband survey from 2014-2019 with this instrument. In this talk, I will focus on the HSC survey Wide Layer, which will cover 1400 square degrees in five broad bands (grizy), to a 5 sigma point-source depth of r~26. We have covered 240 square degrees of the Wide Layer in all five bands, and the median seeing in the i band is 0.60 arcseconds. This powerful combination of depth and image quality makes the HSC survey unique compared to other ongoing imaging surveys. In this talk I will describe the HSC survey dataset and the completed and ongoing science analyses with the survey Wide layer, including galaxy studies, strong and weak gravitational lensing, but with an emphasis on weak lensing. I will demonstrate the level of systematics control, the potential for competitive cosmology constraints, some early results, and describe some lessons learned that will be of use for other ongoing and future lensing surveys.

"Astronomy with Superconductors: A Review of Current and Upcoming Photon Detector Technologies"

Omid Noroozian

NRAO

Tuesday, Feb 6, 2018

Abstract

Technological advances in photon detectors, spectrometers, and amplifiers have enabled increasingly more powerful telescopes, and have been at the heart of new scientific discoveries. New detector technologies have enabled entirely new observational possibilities that had not been previously considered in the design of science studies. In this talk I will review, across the electromagnetic spectrum (with some focus in the Submm/Far-IR), the state-of-the-art detector technologies that involve the use of one of nature’s strangest properties, namely superconductivity. Kinetic Inductance Detectors, Transition Edge Sensors, Quantum Capacitance Detectors, Traveling-Wave Parametric Amplifiers, on-chip spectrometers, and heterodyne receivers are all exciting technologies that will play a key role in future space and ground-based facilities, such as the Origins Space Telescope (OST), SPICA, Atacama Large-Aperture Submm/mm Telescope (AtLAST), CMB-S4, and upgrades to current facilities such as ALMA. Their science impact ranges from exoplanet atmospheric studies and protoplanetary disk evolution to large-scale spectroscopic surveys of high-z galaxies.

"Kepler’s Final Planet Catalog"

Susan Mullally Thompson

STScI

Tuesday, Feb 13, 2018

Abstract

The Kepler mission spent four years staring at the same patch of sky, in half hour increments, in order to catch the small, periodic decreases in brightness caused by a planet transiting its host star. Kepler caused a revolution in planet discoveries by enabling the discovery of a variety of planets, including rocky planets and planets in the habitable zone of their stars. However, the true goal of Kepler was to enable a statistical census of planets, especially those planets that are similar to the Earth. Since the Kepler spacecraft stopped taking data in 2013, this effort has continued by understanding the data characteristics, improving the data processing pipeline, and doing one final search of the data for transiting exoplanets. The culmination of that effort is the DR25 planet candidate catalog. To produce this final planet candidate catalog we automated the entire search, from time series pixel data to planet candidates. By feeding the this fully automated pipeline a set of simulated signals we could directly test our pipeline and determine how much the catalog was contaminated by noise and account for how many plants were missed. In this talk I will give an overview of the Kepler mission and what it has added to our understanding of exoplanets, how the final planet catalog was designed to determine the frequency of small, long-period planets and what challenges remain in using this catalog to determine the frequency of Earth-like planets in our Galaxy.

"GW170817 Optical/NIR Follow-up Observations: The First Evidence of Kilonovae Existence"

Silvia Piranomonte

INAF/Rome

Tuesday, Feb 20, 2018

Abstract

On August 17th 2017 the first electromagnetic counterpart of a gravitational wave (GW) event originated by the coalescence of a double neutron star system (GW 170817, Abbott et al. 2017) was finally observed. A world-wide extensive observing campaign was carried out to follow-up and study this source In this talk I will describe our unique spectroscopic dataset acquired with the VLT which allowed to characterize and identify the optical counterpart of GW 170817 as the first compelling example of a "kilonova", a transient source powered by radioactive decay of heavy elements resulting from the r-process nucleosynthesis of ejected neutron star matter. All the activities I will describe are expected to provide means and opportunities to all the European astronomical communities to have a leading role in the GW astronomy and Time Domain Astronomy.

"Cosmology with X-ray Galaxy Clusters"

Thomas Reiprich

Bonn

Tuesday, Feb 27, 2018

Abstract

The massive dark matter halos that host galaxy clusters can be well traced by X-ray satellite observatories. The intracluster gas trapped in the deep potential wells gets heated to 10s of millions of Kelvin, emitting thermal bremsstrahlung at X-ray wavelengths. The latest cosmological constraints from X-ray selected galaxy clusters will be discussed. A new test to constrain the cosmological luminosity distance anisotropy using galaxy clusters is introduced and results indicating a violation of isotropy are shown. New X-ray selected very extended nearby galaxy groups and clusters have been discovered in ROSAT All-Sky Survey images at positions where no X-ray source was found previously; the properties of the cluster candidate sample (~1,000 in total) and implications for cosmological constraints from clusters are discussed. The current status of and prospects for the eROSITA telescope to be launched aboard the SRG mission in about one year are outlined. The expectations for the ESA L-class mission Athena to discover and characterize early galaxy groups, massive and evolved enough to contain $>$10 million Kelvin gas, above redshift 2 are quantified.

"Exoplanet Atmospheric Composition: a Tracer of Formation Processes"

Mark Swain

JPL

Tuesday, Mar 6, 2018

Abstract

That planets are ubiquitous is now well established but the details of the formation mechanism are not well understood. Theoretical studies suggest that the process of planet formation may leave an imprint on exoplanet atmospheres. When not substantially modified by subsequent evolution, atmospheric composition has the potential to reveal the critical aspects of the planet formation process. The opportunity to probe planet formation in this manor must be balanced with the tremendous diversity that exists for exoplanets – this requires a statistical approach. Transiting planets are well suited for a large-scale, uniform survey; currently we know of more than 2500 transiting planets and TESS is poised to find at least 1500 more around bright stars. Building the success of Kepler and TESS, a large spectroscopic survey of transiting exoplanets would make a decisive contribution to our understanding of planet formation.

"Galaxies at Cosmic Dawn: Exploring the First Billion Years with Hubble and Spitzer - Implications for JWST"

Garth Illingworth

UCSC/Lick

Tuesday, Mar 13, 2018

Abstract

Hubble has revolutionized the discovery and study of the earliest galaxies through its exploration of the universe in the first billion years after the Big Bang. I will discuss what we have learned about galaxies during that epoch at redshift z>6 from the remarkable HST and Spitzer imaging surveys (e.g., GOODS, HUDF/XDF, HUDF09/12 and CANDELS), as well as surveys of lensing galaxy clusters (e.g., the Hubble Frontier Fields - HFF). Lensing clusters provide extraordinary opportunities for characterizing the faintest earliest galaxies, but also present extraordinary challenges. Analysis of early galaxies found in the HFF images reveal compact star-forming regions that, remarkably, can be as small as today's globular clusters and dwarf galaxies. The results from deep surveys with Hubble, combined with the recent results from Planck, indicate that galaxies dominated the UV ionizing flux that reionized the universe. One of the greatest surprises came from the discovery of very luminous galaxies at redshifts z~11 to z~8, just 400 to 650 million years after the Big Bang. Hubble and Spitzer recently encroached on JWST territory by looking back through 97% of all time to confirm a z~11.1 galaxy. This is far beyond what we ever expected Hubble and Spitzer could do. Twenty years of astonishing progress with Hubble and Spitzer leave me looking to JWST to provide even more remarkable exploration of the realm of the first galaxies. I will discuss how the latest Hubble and Spitzer results on the sizes of star-forming regions in distant galaxies, on the star formation rate at redshift z~10, and from Planck indicating that reionization began around z~10, together have significant implications for the detectability of the "first galaxies" with JWST.

"The Probe-Class Mission Concept, CETUS"

Sally Heap

GSFC

Tuesday, Mar 20, 2018

Abstract

CETUS is UV mission concept selected by NASA for study as a Probe-class mission (full life-cycle costs of $400M to $1B). The mission concept features a 1.5-m telescope with 3 scientific instruments: a near-UV multi-object spectrograph, a near-UV/far-UV wide-field camera, and a near-UV/far-UV point-source spectrograph. CETUS is by no means a poor man's Hubble Space Telescope. Instead, it focuses on doing things that Hubble can't do. CETUS will have the agility to respond rapidly to important astrophysical transient sources such as the UV afterglow of gamma-ray bursts or tidal disruption events. With its Goddard-made micro-shutter array, it will obtain spectra of ~100 faint galaxies at z~1-2 in a single shot. These spectra will help identify physical processes driving galaxy evolution at a turning point in the star-formation history of the universe. The point-source spectrograph will probe deep in the far-UV to study the multi-phase circum-galactic medium around galaxies -- likely the major repository of mass and metals in the modern universe.

"Asteroseismology & Exoplanet Host Stars in the Era of Gaia & TESS"

Dan Huber

IfA/Hawaii

Tuesday, Mar 27, 2018

Abstract

Asteroseismology - the study of stellar oscillations - is a powerful tool to probe the structure and evolution of stars. In addition to the large number of discovered exoplanets, space-based telescopes such as Kepler/K2 have revolutionized asteroseismology by detecting oscillations in thousands of stars from the main sequence to the red-giant branch. In this talk I will highlight recent discoveries in asteroseismology, focusing in particular on synergies with exoplanet science such as the precise measurement of planet compositions and the determination of dynamical architectures of planetary systems. I will also discuss the expected impact of Gaia on asteroseismology and exoplanet host stars, such as the comparison of asteroseismic radii with radii derived from Gaia parallaxes and the re-characterization of the entire Kepler target sample. Finally, I will discuss prospects and data analysis challenges for asteroseismology with TESS, which is expected to increase the asteroseismic yield by at least one order of magnitude compared to Kepler/K2.

"Exploring the Inner Structure of Active Galactic Nuclei by Reverberation"

Brad Peterson

Space Telescope Science Institute and The Ohio State University

Tuesday, Apr 3, 2018

Abstract

The innermost structure of active galactic nuclei (AGNs) consists of an accretion disk surrounding a supermassive black hole and, on somewhat larger scales, rapidly moving diffuse gas. The ultraviolet through near IR spectrum of AGNs is dominated by thermal continuum emission from the accretion disk and broad emission lines and absorption features from the diffuse gas. The continuum flux from the accretion disk varies with time, and the emission lines also change in brightness, or “reverberate,” in response to these variations, with a delay due to the light-travel time across the line-emitting region. Measurement of the emission-line time delay yields the size of the line-emitting region and by combining this with the emission-line Doppler width, the central black hole mass can be inferred. I will discuss results from recent “reverberation mapping” experiments, including a 179-orbit Hubble Space Telescope program, that have been designed to explore the dynamics of the emission-line gas and are yielding a wealth of new and quite surprising information about AGN structure.

"SPHEREx: An All-sky Infrared Spectral Survey Explorer Satellite"

Jamie Bock

California Institute of Technology

Tuesday, Apr 10, 2018

Abstract

SPHEREx, a mission in NASA's Medium Explorer (MIDEX) program that was selected for a competitive Phase A in August 2017, is an all-sky survey satellite designed to address all three science goals in NASA's astrophysics division, with a single instrument, a wide-field spectral imager. We will probe the physics of inflation by measuring non-Gaussianity by studying large-scale structure, surveying a large cosmological volume at low redshifts, complementing high-z surveys optimized to constrain dark energy. The origin of water and biogenic molecules will be investigated in all phases of planetary system formation - from molecular clouds to young stellar systems with protoplanetary disks - by measuring ice absorption spectra. We will chart the origin and history of galaxy formation through a deep survey mapping large-scale spatial power in two deep fields located near the ecliptic poles. Following in the tradition of all-sky missions such as IRAS, COBE and WISE, SPHEREx will be the first all-sky near-infrared spectral survey. SPHEREx will create spectra (0.75 – 5 um at R = 35 - 130) with high sensitivity using a cooled telescope with a wide field-of-view for large mapping speed. During its two-year mission, SPHEREx will produce four complete all-sky maps that will serve as a rich archive for the astronomy community. With over a billion detected galaxies, hundreds of millions of high-quality stellar and galactic spectra, and over a million ice absorption spectra, the archive will enable diverse scientific investigations including studies of young stellar systems, brown dwarfs, high-redshift quasars, galaxy clusters, the interstellar medium, asteroids and comets. SPHEREx is a partnership between Caltech, JPL, Ball Aerospace, and the Korea Astronomy and Space Science Institute.

"The Radio Synchrotron Background: Recent Reckonings"

Jack Singal

Richmond

Tuesday, Apr 17, 2018

Abstract

It has become increasingly clear that there is profound tension between measurements of the background level of diffuse radio emission on our sky on the one hand and the integrated surface brightness expected from extragalactic source counts of known populations and most reasonable models of the Galactic halo on the other. These seemingly irreconcilable results represent a mystery in astrophysics, and make studies of the radio background fundamentally unlike those at infrared, optical/UV, X-ray, and gamma-ray wavelengths where the source populations are well characterized and understood, and trace the known large scale structure of the Universe. This talk will review the measurements of the radio synchrotron monopole level, and the constraints on properties of extragalactic radio sources and on Galactic diffuse emission. We will then present the ideas for paths forward and future measurements that were arrived at a recent international workshop on the topic.

"The continuing mystery of multiple spectral components in Jets from Black Holes"

Eileen Meyer

UMBC

Tuesday, Apr 24, 2018

Abstract

One of the first things that astronomers usually determine for any new astrophysical source class is the emission process generating the radiation -- thermal, synchrotron, inverse Compton, Bremsstrahlung, etc. Identifying these processes is critical to using the EM observations to probe the physical environments of very distant objects. Despite the fact that jets from black holes were first understood to exist over 40 years ago, we are still in ignorance about many primary aspects of these systems -- including the radiation mechanism at high energies, the particle makeup of the jets, and how particles are accelerated, possibly to energies as high as 100 TeV and hundreds of kpc from the central engine. I will discuss how this mystery first really got going with the launch of Chandra in 1999, and show how high-resolution observations with observatories like Hubble and ALMA have continued to add pieces to the puzzle -- sometimes seemly solving a problem, and other times opening a new one. I will conclude with some perspectives on how new observatories, like the Chandra successors AXIS and Lynx, can help us solve these long-open questions in jet physics.

"The Dark Matter in the Universe"

Katie Freese

UMich

Tuesday, May 1, 2018

Abstract

"What is the Universe made of?" This question is the longest outstanding problem in all of modern physics, and it is one of the most important research topics in cosmology and particle physics today. The bulk of the mass in the Universe is thought to consist of a new kind of dark matter particle, and the hunt for its discovery in on. I'll start by discussing the evidence for the existence of dark matter in galaxies, and then show how it fits into a big picture of the Universe containing 5% atoms, 25% dark matter, and 70% dark energy. Neutrinos only constitute ½% of the content of the Universe, but much can be learned about neutrino properties from cosmological data. Leading candidates for the dark matter are Weakly Interacting Massive Particles (WIMPs), axions, and sterile neutrinos. WIMPs are a generic class of particles that are electrically neutral and do not participate in strong interactions, yet have weak-scale interactions with ordinary matter. There are multiple approaches to experimental searches for WIMPS: at the Large Hadron Collider at CERN in Geneva; in underground laboratory experiments; with astrophysical searches for dark matter annihilation products, and upcoming searches with the James Webb Space Telescope for Dark Stars, early stars powered by WIMP annihilation. Current results are puzzling and the hints of detection will be tested soon. At the end of the talk I'll briefly turn to dark energy and its effect on the fate of the Universe.

"Can Big Data Lead an Inclusion Revolution?"

Dara Norman

Deputy Associate Director for NOAO’s Community Science and Data Center

Tuesday, May 8, 2018

Abstract

Ground-based astronomy research is evolving into an era of large surveys and big datasets. With the help of federal funding, many of these datasets are already accessible through public archives and databases. The Large Synoptic Survey Telescope, expected to begin Science Verification in 2021, will be the flagship ground-based facility into the next decade. The survey is an opportunity for a research ‘Inclusion Revolution’ by providing data and data products for use by all members of the science community. However, this revolution can only be realized if 1) data products are not just accessible, but discoverable and easily useable, and 2) if the broad community of astronomers is prepared to use tools and services to take advantage of these datasets for achieving science goals. At NOAO we are actively engaged in several programs to support the broad science community’s use of current data holdings and near-term public surveys as we prepare for the big data sets that will flow once the LSST survey begins. In this talk, I will describe these efforts.

"Imaging Exoplanets from the Next Generation of Space Telescopes"

Jeremy Kasdin

Princeton

Tuesday, May 15, 2018

Abstract

With the discoveries of thousands of exoplanets over the last decade from both ground telescopes and space (namely the Kepler mission), the field of exoplanet science has been revolutionized. We now know that exoplanets are common, that small planets far outnumber large ones, and that solar systems come in a myriad of forms. The next revolution will come with the advent of direct imaging from space. This will make accessible planets down to Earth size and will provide information on the chemical makeup of the planets and their atmospheres. Within the next 15 years we may for the first time image an earth and search for evidence of life. This new era will begin with the launch of NASA’s WFIRST spacecraft in 2025, the first telescope with a high performance, active coronagraph enabling direct imaging and spectroscopy of large planets. In this talk I will describe the basics of high-contrast imaging, the key technologies developed over the last decade to make it possible, and the coronagraph instrument on WFIRST. I’ll highlight advances being made in wavefront estimation and control that make possible the very high contrast needed for future Earth imaging missions. I will also describe how starshades can be used for exoplanet imagine and how a starshade may give us the first image of an Earth size planet in the habitable zone of a nearby star.

"Multimessenger Signatures of Massive Black Holes in Dwarf Galaxies"

Jillian Bellovary

QCC/CUNY

Tuesday, May 22, 2018

Abstract

Inspired by the recent discovery of several nearby dwarf galaxies hosting active galactic nuclei, I will present results from a series of cosmological hydrodynamic simulations focusing on dwarf galaxies which host supermassive black holes (SMBHs). Cosmological simulations are a vital tool for predicting SMBH populations and merger events which will eventually be observed by LISA. Dwarf galaxies are the most numerous in the universe, so even though the occupation fraction of SMBHs in dwarfs is less than unity, their contribution to the gravitational wave background could be non-negligible. I find that electromagnetic signatures from SMBH accretion are not common among most SMBH-hosting dwarfs, but the gravitational wave signatures can be substantial. The most common mass ratio for SMBH mergers in low-mass galaxy environments is ~1:20, which is an unexplored region of gravitational waveform parameter space. I will discuss the occupation fraction of SMBHs in low-mass galaxies as well as differences in field and satellite populations, providing clues to search for and characterize these elusive giants lurking in the dwarfs.

"The installation and ongoing commissioning of the MATISSE mid-infrared interferometer at the ESO Very Large Telescope Observatory"

Bruno Lopez

Astronomé, Observatoire de la Côte d'Azur, Nice, France

Tuesday, May 29, 2018

Abstract

MATISSE (Multi AperTure mid-Infrared SpectroScopic Experiment) is the spectro-interferometer for the VLTI of the European Southern Observatory (ESO), operating in the L-, M- and N- spectral bands, and it combines up to four beams from the Unit or the Auxiliary Telescopes (UTs or ATs). The instrument has been studied and designed to tackle several science objectives of importance including the observations of inner regions of protoplanetary disks aiming at a better understanding of the formation of terrestrial like planets. I will present our last months of preparation and the status of the instrument which has been shipped to Cerra Paranal on the site of ESO Very Large Telescope in October. The instrument is currently in its commissioning plan. I will report on the first performance estimate of the instrument.

"Exploring compact-binary astrophysics with multi-messenger astronomy"

Katie Breivik

Tuesday, June 5, 2018

Abstract

The most promising probe into compact binary formation and evolution will be the populations observed by both gravitational wave (GW) and electromagnetic (EM) telescopes. As with any observation, biases must be characterized to gain a deeper understanding of the underlying physics governing the observed population. Investigation of these biases in population synthesis studies requires a study of the variance in the observable population from a statistical sample of population realizations. In this talk, I will introduce a population synthesis code, COSMIC, which provides a key necessity in understanding the compact binary populations observable by current and future GW and EM observatories: the ability to generate a statistical sample of observable compact binary populations using the same computational power as previous population synthesis methods. I will also present results from two recent studies which used COSMIC to show LISA and Gaia together could characterize hundreds of accreting double white dwarfs and Gaia could discover thousands of black holes by the end of its mission.

"Remote Occulter for the 2020's"

Eliad Peretz & Dr. John Mather

GSFC

Tuesday, July 10, 2018

Abstract

We show that a ground-based telescope augmented with a starshade flying in formation in space could detect observe and characterize exoplanets in a wide range of bands; this starshade could also be used with space telescopes. The starshade provides the needed suppression of glare from a host star to image small exoplanets, to measure their spectra, and to observe their orbital motions. The needed technology, while difficult, is not impossible. Three 30-m class telescopes are already under construction (E-ELT, GMT, TMT) and all will provide extreme adaptive optics working at visible and near IR wavelengths. With their enormous collecting area, angular resolution of a few milli-arcseconds, and high-resolution spectroscopy, these observatories have unique capabilities that would not be duplicated even with advanced space telescopes now under study. We show what such a ground-space combination could observe, review the scientific questions it could address, and describe the engineering concept and technology development that would be required for success.