We present a close companion search around sixteen known early-L dwarfs using aperture masking interferometry with Palomar laser guide star adaptive optics. The use of aperture masking allows the detection of close binaries, corresponding to projected physical separations of 0.6-10.0 AU for the targets of our survey. This survey achieved median contrast limits of Delta_K ~ 2.3 for separations between 1.2 - 4 lambda/D, and Delta_K ~ 1.4 at (2/3)lambda/D. We present four candidate binaries detected with moderate to high confidence (90-98%). Two have projected physical separations less than 1.5 AU. This may indicate that tight-separation binaries contribute more significantly to the binary fraction than currently assumed, consistent with spectroscopic and photometric overluminosity studies. Ten targets of this survey have previously been observed with the Hubble Space Telescope as part of companion searches. We use the increased resolution of aperture masking to search for close or dim companions that would be obscured by full aperture imaging, finding two candidate binaries. This survey is the first application of aperture masking with laser guide star adaptive optics at Palomar. Several new techniques for the analysis of aperture masking data in the low signal to noise regime are explored.

David Bernat Antonin H. Bouchez Michael Ireland Peter Tuthill Frantz Martinache John Angione Rick S. Burruss John L. Cromer Richard G. Dekany Stephen R. Guiwits John R. Henning Jeff Hickey Edward Kibblewhite Daniel L. McKenna Anna M. Moore Harold L. Petrie Jennifer Roberts J. Chris Shelton Robert P. Thicksten Thang Trinh Renu Tripathi Mitchell Troy Tuan Truong Viswa Velur James P. Lloyd

Many models of physics beyond the Standard Model yield exotic Higgs decays. Some of these, particularly those in which the Higgs decays to light quarks or gluons, can be very difficult to discover experimentally. Here we introduce a new set of jet substructure techniques designed to search for such a Higgs when its dominant decay is into gluons via light, uncolored resonances. We study this scenario in both V+h and tt+h production channels, and find both channels lead to discovery at the LHC with more than 5 sigma significance at 100 inverse femtobarn.

Adam Falkowski David Krohn Jessie Shelton Arun Thalapillil Lian-Tao Wang

We report a Far Ultraviolet Spectroscopic Explorer satellite observation of the supernova remnant N49 in the Large Magellanic Cloud, covering the 905 -- 1187 A spectral region. A 30'' square aperture was used, resulting in a velocity resolution of ~100 km/s. The purpose of the observation was to examine several bright emission lines expected from earlier work and to demonstrate diffuse source sensitivity by searching for faint lines never seen previously in extragalactic supernova remnant UV spectra. Both goals were accomplished. Strong emission lines of O VI 1031.9 A, 1037.6 A and C III 977.0 A were seen, Doppler broadened to +/- 225 km/s and with centroids red-shifted to 350 km/s, consistent with the LMC. Superimposed on the emission lines are absorptions by C III and O VI 1031.9 at +260 km/s, which are attributed to warm and hot gas (respectively) in the LMC. The O VI 1037.6 A line is more severely affected by overlying interstellar and H2 absorption from both the LMC and our galaxy. N III 989.8 A is not seen, but models indicate overlying absorption severely attenuates this line. A number of faint lines from hot gas have also been detected, many of which have never been seen in an extragalactic supernova remnant spectrum.

William P. Blair Ravi Sankrit Robin Shelton Kenneth R. Sembach H. Warren Moos John C. Raymond Donald G. York Paul D. Feldman Pierre Chayer Edward M. Murphy David J. Sahnow Erik Wilkinson

HD 8673 hosts a massive exoplanet in a highly eccentric orbit (e=0.723). Based on two epochs of speckle interferometry a previous publication identified a candidate stellar companion. We observed HD 8673 multiple times with the 10 m Keck II telescope, the 5 m Hale telescope, the 3.63 m AEOS telescope and the 1.5m Palomar telescope in a variety of filters with the aim of confirming and characterizing the stellar companion. We did not detect the candidate companion, which we now conclude was a false detection, but we did detect a fainter companion. We collected astrometry and photometry of the companion on six epochs in a variety of filters. The measured differential photometry enabled us to determine that the companion is an early M dwarf with a mass estimate of 0.33-0.45 M?. The companion has a projected separation of 10 AU, which is one of the smallest projected separations of an exoplanet host binary system. Based on the limited astrometry collected, we are able to constrain the orbit of the stellar companion to a semi-major axis of 35{60 AU, an eccentricity ? 0.5 and an inclination of 75{85?. The stellar companion has likely strongly in uenced the orbit of the exoplanet and quite possibly explains its high eccentricity.

Lewis C. Roberts, Jr. Brian D. Mason Christopher R. Neyman Yanqin Wu Reed L. Riddle J. Christopher Shelton John Angione Christoph Baranec Antonin Bouchez Khanh Bui Rick Burruss Mahesh Burse Pravin Chordia Ernest Croner Hillol Das Richard G. Dekany Stephen Guiwits David Hale John Henning Shrinivas Kulkarni Nicholas Law Dan McKenna Jennifer Milburn Dean Palmer Sujit Punnadi A. N. Ramaprakash Jennifer E. Roberts Shriharsh P. Tendulkar Thang Trinh Mitchell Troy Tuan Truong Jeff Zolkower

With the goal of understanding why X-rays have been reported near some high velocity clouds, we perform detailed 3 dimensional hydrodynamic and magnetohydrodynamic simulations of clouds interacting with environmental gas like that in the Galaxy's thick disk/halo or the Magellanic Stream. We examine 2 scenarios. In the first, clouds travel fast enough to shock-heat warm environmental gas. In this scenario, the X-ray productivity depends strongly on the speed of the cloud and the radiative cooling rate. In order to shock-heat environmental gas to temperatures of > or = 10^6 K, cloud speeds of > or = 300 km/s are required. If cooling is quenched, then the shock-heated ambient gas is X-ray emissive, producing bright X-rays in the 1/4 keV band and some X-rays in the 3/4 keV band due to O VII and other ions. If, in contrast, the radiative cooling rate is similar to that of collisional ionizational equilibrium plasma with solar abundances, then the shocked gas is only mildly bright and for only about 1 Myr. The predicted count rates for the non-radiative case are bright enough to explain the count rate observed with XMM-Newton toward a Magellanic Stream cloud and some enhancement in the ROSAT 1/4 keV count rate toward Complex C, while the predicted count rates for the fully radiative case are not. In the second scenario, the clouds travel through and mix with hot ambient gas. The mixed zone can contain hot gas, but the hot portion of the mixed gas is not as bright as those from the shock-heating scenario.

Robin L. Shelton Kyujin Kwak David B. Henley

We present predictions of the Si iv ions in turbulent mixing layers (TMLs) between hot and cool gas and in cool high-velocity clouds (HVCs) that travel through a hot halo, complementing the C iv, N v, and O vi predictions in Kwak & Shelton, Kwak et al., and Henley et al. We find that the Si iv ions are most abundant in regions where the hot and cool gases first begin to mix or where the mixed gas has cooled significantly. The predicted column densities of high velocity Si iv and the predicted ratios of Si iv to C iv and O vi found on individual sightlines in our HVC simulations are in good agreement with observations of high velocity gas. Low velocity Si iv is also seen in the simulations, as a result of decelerated gas in the case of the HVC simulations and when looking along directions that pass perpendicular to the direction of motion in the TML simulations. The ratios of low velocity Si iv to C iv and O vi in the TML simulations are in good agreement with those recorded for Milky Way halo gas, while the ratio of Si iv to O vi from the decelerated gas in the HVC simulations is lower than that observed at normal velocity in the Milky Way halo. We attribute the shortfall of normal velocity Si iv to not having modeled the effects of photoionization and, following Henley et al., consider a composite model that includes decelerated HVC gas, supernova remnants, galactic fountain gas, and the effect of photoionization.

Kyujin Kwak Robin L. Shelton David B. Henley

Precision measurements of observables in neutron $\beta$-decay are used to test the Standard Model description of the weak interaction and search for evidence of new physics. The Nab experiment at the Fundamental Neutron Physics Beamline at the Spallation Neutron Source was constructed to measure correlations in neutron decay by utilizing an asymmetric spectrometer and novel detection system to accurately reconstruct the proton momentum and electron energy for each $\beta$-decay. This work describes the detection of neutron $\beta$-decay products in the Nab spectrometer and presents the first full Dalitz plot representation of the phase space of neutron $\beta$-decay for all electrons >100 keV. In addition, new constraints are placed on a possible excited neutron state, hypothesized to explain the disagreement between the appearance and disappearance neutron lifetime techniques.

Francisco M. Gonzalez Jin Ha Choi Himal Acharya Skylar Clymer Andrew Hagemeier David G. Mathews August Mendelsohn Austin Nelsen Hitesh Rahangdale Love Richburg Ricardo Alarcon Ariella Atencio Stefan Baeßler Thomas Bailey Noah Birge Dennis Borissenko Michael Bowler Leah J. Broussard Albert T. Bryant Jimmy Caylor Tim Chupp Christopher Crawford R. Alston Croley Micah Cruz George Dodson Wenjiang Fan Deion Fellers Nadia Fomin Emil Frlež Matthew Frost Jason Fry Duncan Fuehne Michael T. Gericke Michelle Gervais Corey Gilbert Ferenc Glück Rebecca Godri Geoff L. Greene William Greene Josh Hamblen Paul Harmston Leendert Hayen Carter Hedinger Chelsea Hendrus Sean Hollander Kavish Imam Erik B. Iverson Aaron Jezghani Chenyang Jiang Huangxing Li Nick Macsai Mark Makela Russell Mammei Ricky Marshall Madelyn Martinez Mark McCrea Pat McGaughey Sean McGovern David McLaughlin Jacqueline Mirabal-Martinez Paul Mueller Andrew Mullins William Musk Jordan O'Kronley Seppo I. Penttilä D. Elliot Perryman Josh Pierce Jason A. Pioquinto Dinko Počanić Hunter Presley John Ramsey Glenn Randall Zachary Raney Jackson Ricketts Grant Riley Americo Salas-Bacci Sepehr Samiei Alexander Saunders Wolfgang Schreyer E. Mae Scott Thomas Shelton Aryaman Singh Alexander Smith Erick Smith Eric Stevens R. J. Taylor Leonard Tinius Isaiah Wallace Jonathan Wexler W. Scott Wilburn A. R. Young B. Zeck

We have analyzed a pair of Suzaku XIS1 spectra of the soft X-ray background, obtained by observing towards and to the side of a nearby (d = 230 pc) absorbing filament in the southern Galactic hemisphere. We fit multicomponent spectral models to the spectra in order to separate the foreground emission due to the Local Bubble (LB) from the background emission due to the Galactic halo and unresolved AGN. We obtain LB and halo parameters that are different from those obtained from our analysis of XMM-Newton spectra from these same directions. The LB temperature is lower (log T = 5.93 versus 6.06), and the flux due to the LB in the Suzaku band is an order of magnitude less than is expected from our XMM-Newton analysis. The halo components, meanwhile, are hotter than previously determined, implying our Suzaku spectra are harder than our XMM-Newton spectra.

David B. Henley Robin L. Shelton

Recent X-ray studies have shown that supernova shock models are unable to satisfactorily explain X-ray emission in the rim of the Cygnus Loop. In an attempt to account for this anomalously enhanced X-ray flux, we fit the region with a model including theoretical charge exchange (CX) data along with shock and background X-ray models. The model includes the CX collisions of $O^{8+}$, $O{7+}$, $N^{7+}$, $N^{6+}$, $C^{6+}$, and $C^{5+}$ with H with an energy of 1 keV/u (438 km/s). The observations reveal a strong emission feature near 0.7 keV that cannot fully be accounted for by a shock model, nor the current CX data. Inclusion of CX, specifically $O^{7+} + H$, does provide for a statistically significant improvement over a pure shock model.

Renata S. Cumbee David B. Henley Phillip C. Stancil Robin L. Shelton Jeff L. Nolte Yong Wu David R. Schultz

In this work, we consider the case of a strongly coupled dark/hidden sector, which extends the Standard Model (SM) by adding an additional non-Abelian gauge group. These extensions generally contain matter fields, much like the SM quarks, and gauge fields similar to the SM gluons. We focus on the exploration of such sectors where the dark particles are produced at the LHC through a portal and undergo rapid hadronization within the dark sector before decaying back, at least in part and potentially with sizeable lifetimes, to SM particles, giving a range of possibly spectacular signatures such as emerging or semi-visible jets. Other, non-QCD-like scenarios leading to soft unclustered energy patterns or glueballs are also discussed. After a review of the theory, existing benchmarks and constraints, this work addresses how to build consistent benchmarks from the underlying physical parameters and present new developments for the PYTHIA Hidden Valley module, along with jet substructure studies. Finally, a series of improved search strategies is presented in order to pave the way for a better exploration of the dark showers at the LHC.

Guillaume Albouy Jared Barron Hugues Beauchesne Elias Bernreuther Marcella Bona Cesare Cazzaniga Cari Cesarotti Timothy Cohen Annapaola de Cosa David Curtin Zeynep Demiragli Caterina Doglioni Alison Elliot Karri Folan DiPetrillo Florian Eble Carlos Erice Chad Freer Aran Garcia-Bellido Caleb Gemmell Marie-Hélène Genest Giovanni Grilli di Cortona Giuliano Gustavino Nicoline Hemme Tova Holmes Deepak Kar Simon Knapen Suchita Kulkarni Luca Lavezzo Steven Lowette Benedikt Maier Seán Mee Stephen Mrenna Harikrishnan Nair Jeremi Niedziela Christos Papageorgakis Nukulsinh Parmar Christoph Paus Kevin Pedro Ana Peixoto Alexx Perloff Tilman Plehn Christiane Scherb Pedro Schwaller Jessie Shelton Akanksha Singh Sukanya Sinha Torbjörn Sjöstrand Aris G. B. Spourdalakis Daniel Stolarski Matthew J. Strassler Andrii Usachov Carlos Vázquez Sierra Christopher B. Verhaaren Long Wang