Astrophysics and Astronomy Commons^™

The Spitzer Survey Of Stellar Structure In Galaxies (S4g) : Stellar Masses, Sizes, And Radial Profiles For 2352 Nearby Galaxies., Juan Carlos Muñoz-Mateos, Kartik Sheth, Michael Regan, Taehyun Kim, Jarkko Laine, Santiago Erroz-Ferrer, Armando Gil De Paz, Sebastien Comeron, Joannah Hinz, Eija Laurikainen, Heikki Salo, E. Athanassoula, Albert Bosma, Alexandre Y. Bouquin, Eva Schinnerer, Luis C. Ho, Johan H. Knapen, Sharon Meidt, Miguel Querejeta, Trisha Mizusawa, Mark Seibert, Seppo Laine, Helene M. Courtois

Faculty and Staff Scholarship

The Spitzer Survey of Stellar Structure in Galaxies is a volume, magnitude, and size-limited survey of 2352 nearby galaxies with deep imaging at 3.6 and 4.5 μm. In this paper, we describe our surface photometry pipeline and showcase the associated data products that we have released to the community. We also identify the physical mechanisms leading to different levels of central stellar mass concentration for galaxies with the same total stellar mass. Finally, we derive the local stellar mass–size relation at 3.6 μm for galaxies of different morphologies. Our radial profiles reach stellar mass surface densities below ~1 pc M …

A Search For Planets And Brown Dwarfs Around Post Main Sequence Stars, Tomomi Otani

Theses and Dissertations

So far, the most promising theory for the existence of subdwarf B (sdB) stars is that they were formed during binary star evolution. This research was conducted to test this theory by searching for companions around six sdB pulsators (V391 Peg, HS 0702+6043, EC 20117-4014, PG 1219+534, PG 0911+456, and PG 1613+426) using the Observed-minus-Calculated (O-C) method. A star’s position in space will wobble due to the gravitational forces of any companion. If the star is emitting a periodic signal, the orbital motion of the star around the system’s center of mass causes periodic changes in the light pulse arrival …

Analysis Of Angular Momentum In Planetary Systems And Host Stars, Stacy Ann Irwin

Theses and Dissertations

The spin angular momentum of single Main Sequence stars has long been shown to follow a primary power law of stellar mass, J ∝ Mα, excluding stars of <2 solar masses. Lower mass stars rotate more slowly with and have smaller moments of inertia, and as a result they contain much less spin angular momentum. A secondary power law describes the upper bound of angular momenta of these less massive stars with a steeper slope. The Solar System’s orbital angular momentum, however, is of the same order of magnitude as the primary law, whereas the Sun’s spin angular momentum is consistent with the secondary relationship. This suggests that planets are an important clue to answering questions about stellar angular momentum loss and transfer. With recent advances in exoplanet discovery and characterization, the angular momenta of exoplanetary systems can now be determined. A method is developed to calculate planetary system angular momenta from the spin and orbital angular momenta of a sample including 426 host stars and 532 planets. To maximize the size of the working sample, systems discovered by both the transit and radial velocity methods are included, and the biases of both techniques are identified. Self-consistent stellar moment of inertia parameters are interpolated from grids of stellar evolutionary models. Main Sequence host stars range from 0.6 to 1.7 solar masses, and their angular momenta are shown to agree well with previous studies of stellar angular momentum, generally falling on or below the appropriate power law, and exhibiting detection method biases. The systems’ angular momenta, including both the planetary orbital and stellar spin components, are widely spread above and below the primary power law, but on average agree well with the primary relationship. The results indicate that the primary power law describes angular momenta of stars of <2 solar masses well, when planetary angular momentum is included. This relationship also holds across host star evolutionary classifications. For 90% of the systems, the angular momentum contained in the planets is greater than the spin angular momentum of the host star, a characteristic shared by the Solar System. Undetected planets contribute significant bias to the system angular momentum as well as to the proportion of angular momentum contained in the planets. This bias is used to identify systems which are likely to harbor additional planets in already known planetary systems, assuming the Solar System’s proportions are typical.

Coexisting Charge And Magnetic Orders In The Dimer-Chain Iridate Ba5Alir2O11, Jsaminka Terzic, J. C. Wang, Feng Ye, W. H. Song, Shujuan Yuan, Saicharan Aswartham, Lance E. De Long, S. V. Streltsov, D. I. Khomskii, Gang Cao

Physics and Astronomy Faculty Publications

We have synthesized and studied single-crystal Ba₅AlIr₂O₁₁ that features dimer chains of two inequivalent octahedra occupied by tetravalent Ir⁴⁺(5d⁵) and pentavalent Ir⁵⁺(5d⁴) ions, respectively. Ba₅AlIr₂O₁₁ is a Mott insulator that undergoes a subtle structural phase transition near T_S=210K and a magnetic transition at T_M=4.5K; the latter transition is surprisingly resistant to applied magnetic fields μ_oH≤12T but more sensitive to modest applied pressure (dT_M/dp≈+0.61K/GPa). All results indicate that the …

Solar Wind Energy Input To The Magnetosheath And At The Magnetopause, T. I. Pulkkinen, A. P. Dimmock, A. Osmane, K. Nykyri

Publications

Using Time History of Events and Macroscale Interactions During Substorms observations, we show that the efficiency of the energy entry through the magnetopause as measured by the Poynting vector normal component depends on the combination of the solar wind speed and the southward component of the interplanetary magnetic field (IMF): Most efficient energy transfer occurs when the IMF BZ is only moderately negative, and the solar wind speed is high. This means that for the same level of solar wind driver parameters (electric field, epsilon, or other), different combinations of V and BZ will produce different driving at the magnetopause. …

Detecting Cosmic Rays Using Cemos Sensors In Consumer Devices, Matthew M. Plewa

2017 Academic High Altitude Conference

Since the time of Victor Hess and his balloon flight that demonstrated that cosmic rays increased with altitude, new detection methods have become widely available to be used on current day flights. One such method is to utilize CCDs with long duration exposures. During the exposures the CCD is exposed to cosmic rays which then leave a track. This phenomenon is caused by the CCD's inability to distinguish between photons of light and charged particles. Such tracks can then be separated from the CCD's background noise and classified.

Observation Of Charge Asymmetry Dependence Of Pion Elliptic Flow And The Possible Chiral Magnetic Wave In Heavy-Ion Collisions, J. Kevin Adkins, Renee Fatemi, Suvarna Ramachandran, L. Adamczyk, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, I. Alekseev, J. Alford, A. Aparin, D. Arkhipkin, E. C. Aschenauer, G. S. Averichev

Physics and Astronomy Faculty Publications

We present measurements of π⁻ and π⁺ elliptic flow, v₂, at midrapidity in Au+Au collisions at √^S_NN=200, 62.4, 39, 27, 19.6, 11.5, and 7.7 GeV, as a function of event-by-event charge asymmetry, A_ch, based on data from the STAR experiment at RHIC. We find that π⁻ (π⁺) elliptic flow linearly increases (decreases) with charge asymmetry for most centrality bins at √^S_NN=27  GeV and higher. At √^S_NN=200  GeV, the slope of the difference of v₂ between π⁻ and π^{+ …}

Directional Camera Control On High Altitude Balloons, Matthew M. Plewa, Brent Scharlau

2017 Academic High Altitude Conference

The research reported in this paper examined the design and control of a gimbal for solar eclipse tracking and video recording. The gimbal design required 3 axes of rotation to allow for full range of motion. Utilizing individual brushless motors for each of the axes ensure minimum rotational requirements on each axes. In controlling the gimbal, both a mathematical and visual method were utilized. The mathematical method is a modified version of what is currently used for solar array pointing. The visual method looks at where the position of the sun is within the image and determines what angle changes …

Double Compact Objects. Iii. Gravitational-Wave Detection Rates, Michal Dominik, Emanuele Berti, Richard O'Shaughnessy, Ilya Mandel, Krzysztof Belczynski, Christopher Fryer, Daniel E. Holz, Tomasz Bulik, Francesco Pannarale

Physics & Astronomy Faculty Publications

The unprecedented range of second-generation gravitational-wave (GW) observatories calls for refining the predictions of potential sources and detection rates. The coalescence of double compact objects (DCOs)—i.e., neutron star–neutron star (NS–NS), black hole–neutron star (BH–NS), and black hole–black hole (BH–BH) binary systems—is the most promising source of GWs for these detectors. We compute detection rates of coalescing DCOs in second-generation GW detectors using the latest models for their cosmological evolution, and implementing inspiral-merger-ringdown gravitational waveform models in our signal-to-noise ratio calculations. We find that (1) the inclusion of the merger/ringdown portion of the signal does not significantly affect rates for NS–NS …

Cosmic Ray Air Shower Lateral Coincidences, Gordon C. Mcintosh

2017 Academic High Altitude Conference

At the University of Minnesota, Morris, my students and I have begun to investigate the time and altitude dependence of air showers. Air showers are cosmic ray secondaries that spread out laterally around the primary cosmic ray direction. To investigate the air showers we have been measuring the lateral coincidences among three Aware RM60 Geiger counters located at 0 cm, 15 cm, and 40 cm. Most of these measurements have been carried out at the surface. The rate of lateral, triple coincidences of Geiger counter with this configuration is 0.053 ±0.013 hr^-1 at the surface. On 4 April 2015 …

First Measurement Of The Atomic Electric Dipole Moment Of 225Ra, R. H. Parker, M. R. Dietrich, M. R. Kalita, N. D. Lemke, K. G. Bailey, M. Bishof, J. P. Greene, R. J. Holt, Wolfgang Korsch, Z.-T. Lu, P. Mueller, T. P. O'Connor, J. T. Singh

Physics and Astronomy Faculty Publications

The radioactive radium-225 (²²⁵Ra) atom is a favorable case to search for a permanent electric dipole moment. Because of its strong nuclear octupole deformation and large atomic mass, ²²⁵Ra is particularly sensitive to interactions in the nuclear medium that violate both time-reversal symmetry and parity. We have developed a cold-atom technique to study the spin precession of ²²⁵Ra atoms held in an optical dipole trap, and demonstrated the principle of this method by completing the first measurement of its atomic electric dipole moment, reaching an upper limit of |d(²²⁵Ra)|<5.0×10⁻²²  e cm …

Star Formation And Quenching Among The Most Massive Galaxies At Z ∼ 1.7, C. Mancini, A. Renzini, E. Daddi, G. Rodighiero, S. Berta, N. Grogin, Dale D. Kocevski, A. Koekemoer

Physics and Astronomy Faculty Publications

We have conducted a detailed object-by-object study of a mass-complete (M_* ≥ 10¹¹ M_⊙) sample of 56 galaxies at 1.4 ≤ z ≤ 2 in the Great Observatories Origins Deep Survey-South field, showing that an accurate deblending in 24 μm images is essential to properly assign to each galaxy its own star formation rate (SFR), whereas an automatic procedure often fails. This applies especially to galaxies with SFRs below the main sequence (MS) value, which may be in their quenching phase. After that, the sample splits evenly between galaxies forming stars within a factor of …

Einstein@ Home Discovery Of A Palfa Millisecond Pulsar In An Eccentric Binary Orbit, B. Knispel, A. G. Lyne, B. W. Stappers, P. C.C. Freire, P. Lazarus, B. Allen, C. Aulbert, O. Bock, S. Bogdanov, Fredrick Jenet

Physics & Astronomy Faculty Publications

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 Mo and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities …

Star Formation And Relaxation In 379 Nearby Galaxy Clusters, Seth A. Cohen, Ryan C. Hickox, Gary A. Wegner

Dartmouth Scholarship

We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes M_r < −19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 ± 0.003) is higher than that in all relaxed clusters (0.097 ± 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters.

A Comprehensive Characterization Of The 70 Virginis Planetary System, Stephen R. Kane, Tabetha S. Boyajian, Gregory W. Henry, Y. Katherina Feng, Natalie R. Hinkel, Debra A. Fischer, Kaspar Von Braun, Andrew W. Howard, Jason T. Wright

Information Systems and Engineering Management Research Publications

An on-going effort in the characterization of exoplanetary systems is the accurate determination of host star properties. This effort extends to the relatively bright host stars of planets discovered with the radial velocity method. The Transit Ephemeris Refinement and Monitoring Survey (TERMS) is aiding in these efforts as part of its observational campaign for exoplanet host stars. One of the first known systems is that of 70 Virginis, which harbors a jovian planet in an eccentric orbit. Here we present a complete characterization of this system with a compilation of TERMS photometry, spectroscopy, and interferometry. We provide fundamental properties of …

Models Of Time Travel And Their Consequences, Antonio M. Mantica

Oglethorpe Journal of Undergraduate Research

How do we travel through time? We know that we can move forward in it (we have no choice), but can we jump forward in time? Can we go backward in time? It also gives rise to other troubling questions: is time measurable in distinct increments, or does it flow continuously? In "Models of Time Travel and their Consequences," Antonio Mantica walks the reader through current understandings of how time functions in Einstein's universe and proposes three distinct models to explain it. Following that, he provides a list of experiments to credit or discredit the models. Appropriate for audiences of …

Update On Radiation Dose From Galactic And Solar Protons At The Moon Using The Lro/Crater Microdosimeter, J. E. Mazur, Cary Zeitlin, Nathan A. Schwadron, M. D. Looper, Lawrence W. Townsend, J. B. Blake, Harlan E. Spence

Physics & Astronomy

The NASA Lunar Reconnaissance Orbiter (LRO) has been exploring the lunar surface and radiation environment since June 2009. In Mazur et al. [2011] we discussed the first 6 months of mission data from a microdosimeter that is housed within the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument onboard LRO. The CRaTER microdosimeter is an early version of what is now a commercially available hybrid that accurately measures total ionizing radiation dose in a silicon target (http://www.teledynemicro.com/product/radiation-dosimeter). This brief report updates the transition from a deep solar minimum radiation environment to the current …

Variable Hard-X-Ray Emission From The Candidate Accreting Black Hole In Dwarf Galaxy Henize 2–10, Thomas J. Whalen, Ryan C. Hickox, Amy E. Reines, Jenny E. Greene

Dartmouth Scholarship

We present an analysis of the X-ray spectrum and long-term variability of the nearby dwarf starburst galaxy Henize 2–10. Recent observations suggest that this galaxy hosts an actively accreting black hole (BH) with mass ~10⁶ . The presence of an active galactic nucleus (AGN) in a low-mass starburst galaxy marks a new environment for AGNs, with implications for the processes by which "seed" BHs may form in the early universe. In this paper, we analyze four epochs of X-ray observations of Henize 2–10, to characterize the long-term behavior of its hard nuclear emission. We analyze observations with Chandra from …

Symmetry And The Arrow Of Time In Theoretical Black Hole Astrophysics, David Garofalo

Faculty Articles

While the basic laws of physics seem time-reversal invariant, our understanding of the apparent irreversibility of the macroscopic world is well grounded in the notion of entropy. Because astrophysics deals with the largest structures in the Universe, one expects evidence there for the most pronounced entropic arrow of time. However, in recent theoretical astrophysics work it appears possible to identify constructs with time-reversal symmetry, which is puzzling in the large-scale realm especially because it involves the engines of powerful outflows in active galactic nuclei which deal with macroscopic constituents such as accretion disks, magnetic fields, and black holes. Nonetheless, the …

Butterfly Pitch-Angle Distribution Of Relativistic Electrons In The Outer Radiation Belt: Evidence Of Nonadiabatic Scattering, Nikolai O. Artemyev, O. V. Agapitov, F. S. Mozer, Harlan E. Spence

Physics & Astronomy

In this paper we investigate the scattering of relativistic electrons in the nightside outer radiation belt (around the geostationary orbit). We consider the particular case of low geomagnetic activity (|Dst|<20 nT), quiet conditions in the solar wind, and absence of whistler wave emissions. For such conditions we find several events of Van Allen probe observations of butterfly pitch angle distributions of relativistic electrons (energies about 1–3 MeV). Many previous publications have described such pitch angle distributions over a wide energy range as due to the combined effect of outward radial diffusion and magnetopause shadowing. In this paper we discuss another mechanism that produces butterfly distributions over a limited range of electron energies. We suggest that such distributions can be shaped due to relativistic electron scattering in the equatorial plane of magnetic field lines that are locally deformed by currents of hot ions injected into the inner magnetosphere. Analytical estimates, test particle simulations, and observations of the AE index support this scenario. We conclude that even in the rather quiet magnetosphere, small scale (magnetic local time (MLT)-localized) injection of hot ions from the magnetotail can likely influence the relativistic electron scattering. Thus, observations of butterfly pitch angle distributions can serve as an indicator of magnetic field deformations in the nightside inner magnetosphere. We briefly discuss possible theoretical approaches and problems for modeling such nonadiabatic electron scattering.

Three Super-Earths Orbiting Hd 7924, Benjamin J. Fulton, Lauren M. Weiss, Evan Sinukoff, Howard Isaacson, Andrew W. Howard, Geoffrey W. Marcy, Gregory W. Henry, Bradford P. Holden, Robert I. Kibrick

Information Systems and Engineering Management Research Publications

We report the discovery of two super-Earth-mass planets orbiting the nearby K0.5 dwarf HD 7924, which was previously known to host one small planet. The new companions have masses of 7.9 and 6.4 ${{M}_{\oplus }}$, and orbital periods of 15.3 and 24.5 days. We perform a joint analysis of high-precision radial velocity data from Keck/HIRES and the new Automated Planet Finder Telescope (APF) to robustly detect three total planets in the system. We refine the ephemeris of the previously known planet using 5 yr of new Keck data and high-cadence observations over the last 1.3 yr with the APF. With …

Gps Phase Scintillation At High Latitudes During Geomagnetic Storms Of 7–17 March 2012 – Part 1: The North American Sector, P. Prikryl, R. Ghoddousi-Fard, E. G. Thomas, J. M. Ruohoniemi, S. G. Shepherd

Dartmouth Scholarship

During the ascending phase of solar cycle 24, a series of interplanetary coronal mass ejections (ICMEs) in the period 7–17 March 2012 caused geomagnetic storms that strongly affected high-latitude ionosphere in the Northern and Southern Hemisphere. GPS phase scintillation was observed at northern and southern high latitudes by arrays of GPS ionospheric scintillation and TEC monitors (GISTMs) and geodetic-quality GPS receivers sampling at 1 Hz. Mapped as a function of magnetic latitude and magnetic local time, regions of enhanced scintillation are identified in the context of coupling processes between the solar wind and the magnetosphere–ionosphere system. Large southward IMF and …

Search For Life, John W. Delano Phd

Atmospheric and Environmental Science Faculty Scholarship

NASA's Astrobiology program seeks to determine the origin and distribution of life in the Milky Way galaxy using scientific expertise from many disciplines (e.g., astronomy, biochemistry, geochemistry). This presentation, which provides an overview of the progress that has been made in this effort, was delivered on 23 June 2015 at the Green Mountain Academy for Lifelong Learning in Manchester, VT. With NASA's development of the Space Launch System (SLS), vigorous multi-disciplinary scientific research, and additional spacecraft (e.g., TESS) for finding and analyzing planets orbiting other stars, exciting discoveries will continue.

A Sluggs And Gemini/Gmos Combined Study Of The Elliptical Galaxy M60: Wide-Field Photometry And Kinematics Of The Globular Cluster System, Vincenzo Pota, Jean Brodie, Terry Bridges, Jay Strader, Aaron Romanowsky, Alexa Villaume, Zach Jennings, Favio Faifer, Nicola Pastorello, Duncan Forbes, Ainsley Campbell, Christopher Usher, Caroline Foster, Lee Spitler, Nelson Caldwell, Juan Forte, Mark Norris, Stephen Zepf, Michael Beasley, Karl Gebhardt, David Hanes, Ray Sharples, Jacob Arnold

Faculty Publications

We present new wide-field photometry and spectroscopy of the globular clusters (GCs) around NGC 4649 (M60), the third brightest galaxy in the Virgo cluster. Imaging of NGC 4649 was assembled from a recently obtained Hubble Space Telescope/Advanced Camera for Surveys mosaic, and new Subaru/Suprime-Cam and archival Canada–France–Hawaii Telescope/MegaCam data. About 1200 sources were followed up spectroscopically using combined observations from three multi-object spectrographs: Keck/Deep Imaging Multi-Object Spectrograph, Gemini/Gemini Multi-Object Spectrograph and Multiple Mirror Telescope/Hectospec. We confirm 431 unique GCs belonging to NGC 4649, a factor of 3.5 larger than previous data sets and with a factor of 3 improvement in …

Spectropolarimetry Of Epsilon Aurigae: Probing Stellar And Disk Atmospheres, Kathleen M. Geise

Electronic Theses and Dissertations

The bright eclipsing binary system epsilon Aurigae offers a unique opportunity to uncover physical mechanisms contributing to disk formation and evolution and to explore the relationship between photospheric anisotropies, stellar pulsation and mass loss. This research contributes to our understanding of stellar evolution in the context of binary stars. The research also offers the opportunity to investigate disk formation and evolution significant to our understanding of protoplanetary disks now seen in many star systems. Lastly, the project considers radiative transfer of polarized light that contributes to diverse fields such as atmospheric studies of exoplanets.

My objective is to understand the …

Precise Mass And Radius Measurements For The Components Of The Bright Solar-Type Eclipsing Binary Star V1094 Tauri, P. F.L. Maxted, R. J. Hutcheon, G. Torres, C. H.S. Lacy, J. Southworth, B. Smalley, K. Pavlovski, Laurence A. Marschall, J. V. Clausen

Physics and Astronomy Faculty Publications

Context. V1094 Tau is a bright eclipsing binary star with an orbital period close to nine days that contains two stars similar to the Sun.

Aims. Our aim is to test models of Sun-like stars using precise and accurate mass and radius measurements for both stars in V1094 Tau.

Methods. We present new spectroscopy of V1094 Tau, which we use to estimate the effective temperatures of both stars and to refine their spectroscopic orbits. We also present new, high-quality photometry covering both eclipses of V1094 Tau in the Strömgren uvby system and in the Johnson V-band.

Results. The masses, …

A Disk-Based Dynamical Mass Estimate For The Young Binary Ak Sco, I. Czekala, S. M. Andrews, Eric L.N. Jensen, K. G. Stassun, G. Torres, D. J. Wilner

Physics & Astronomy Faculty Works

We present spatially and spectrally resolved Atacama Large Millimeter/submillimeter Array (ALMA) observations of gas and dust in the disk orbiting the pre-main sequence (pre-MS) binary AK Sco. By forward-modeling the disk velocity field traced by CO J = 2-1 line emission, we infer the mass of the central binary, {M}_*=2.49+/- 0.10 {M}_☉ , a new dynamical measurement that is independent of stellar evolutionary models. Assuming the disk and binary are co-planar within ̃2°, this disk-based binary mass measurement is in excellent agreement with constraints from radial velocity monitoring of the combined stellar spectra. These ALMA results are …

Faint Agns At Z > 4 In The Candels Goods-S Field: Looking For Contributors To The Reionization Of The Universe, E. Giallongo, A. Grazian, F. Fiore, A. Fontana, L. Pentericci, E. Vanzella, M. Dickinson, Dale D. Kocevski, M. Castellano, S. Christiani, H. Ferguson, S. Finkelstein, N. Grogin, N. Hathi, A. M. Koekemoer, J. A. Newman, M. Salvato

Physics and Astronomy Faculty Publications

Context. Establishing the number of faint active galactic nuclei (AGNs) at z = 4−6 is crucial to understanding their cosmological importance as main contributors to the reionization of the Universe.

Aims. In order to derive the AGN contribution to the cosmological ionizing emissivity we have selected faint AGN candidates at z> 4 in the CANDELS GOODS-South field, which is one of the deepest fields with extensive multiwavelength coverage from Chandra, HST, Spitzer, and various ground-based telescopes.

Methods. We have adopted a relatively novel criterion. As a first step, high redshift galaxies are selected in the NIR H band …

A Feasibility Study Of Photometric Reverberation Mapping With Meter-Class Telescopes, Carla June Carroll

Theses and Dissertations

For the past several decades, mass estimates for supermassive black holes hosted by active galactic nuclei (AGN) have been made with the reverberation mapping (RM) technique. This methodology has produced consistent results and has been used to establish several relations that link the characteristics of the host galaxy to the mass of the central black hole. Despite this success, there are less than 50 AGN with black hole masses derived from RM. This low number is generally attributed to the difficulties in coordinating large blocks of telescope time for making simultaneous photometric and spectroscopic observations. Spectroscopic observations also generally require …

Search For Vector-Like T Quarks Decaying To Top Quarks And Higgs Bosons In The All-Hadronic Channel Using Jet Substructure, Cms Collaboration, V. Khachatryan, A. M. Sirunyan, Marc M. Baarmand, Marcus Hohlmann, Himali Kalakhety, Francisco X. Yumiceva

Aerospace, Physics, and Space Science Faculty Publications

A search is performed for a vector-like heavy T quark that is produced in pairs and that decays to a top quark and a Higgs boson. The data analysed correspond to an integrated luminosity of 19.7 fb⁻¹ collected with the CMS detector in proton-proton collisions at s=8" role="presentation" style="box-sizing: inherit; display: inline-block; line-height: normal; word-spacing: normal; overflow-wrap: normal; text-wrap: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">�=8 TeV. For T quarks with large mass values the top quarks and Higgs bosons can have significant Lorentz …