• The H II galaxy Hubble diagram strongly favours R-h = ct over Lambda CDM

      Wei, Jun-Jie; Wu, Xue-Feng; Melia, Fulvio; Univ Arizona, Dept Phys; Univ Arizona, Dept Astron (OXFORD UNIV PRESS, 2016-12-01)
      We continue to build support for the proposal to use H II galaxies (HIIGx) and giant extragalactic H II regions (GEHR) as standard candles to construct the Hubble diagram at redshifts beyond the current reach of Type Ia supernovae. Using a sample of 25 high-redshift HIIGx, 107 local HIIGx, and 24 GEHR, we confirm that the correlation between the emission -line luminosity and ionized -gas velocity dispersion is a viable luminosity indicator, and use it to test and compare the standard model Lambda CDM and the R-h = ct universe by optimizing the parameters in each cosmology using a maximization of the likelihood function. For the flat Lambda CDM model, the best fit is obtained with Omega(m) = 0.40(-0.09)(+0.09). However, statistical tools, such as the Akaike (AIC), Kullback (KIC) and Bayes (BIC) Information Criteria favour R-h = Ct over the standard model with a likelihood of approximate to 94.8-98.8 per cent versus only per cent. For wCDM (the version of ACDM with a dark -energy equation of state wde = Pde/Pde rather than was t WA = 1), a statistically acceptable fit is realized with Omega(m) = 0.221(-0.14)(+0.16) and wde = 0.511'0'21-5" which, however, are not fully consistent with their concordance values. In this case, wCDM has two more free parameters than R-h = Ct, and is penalized more heavily by these criteria. We find that R-h = Ct is strongly favoured over wCDM with a likelihood of approximate to 92.9-99.6 per cent versus only 0.4-7.1 per cent. The current HIIGx sample is already large enough for the BIC to rule out ACDM/wCDM in favour of R-h = Ct at a confidence level approaching 3 sigma.
    • H-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia

      Cunha, K.; Univ Arizona, Steward Observ (EDP Sciences, 2019-07-22)
      We present an elemental abundance analysis of high-resolution spectra for five giant stars spatially located within the innermost regions of the bulge globular cluster NGC 6522 and derive Fe, Mg, Al, C, N, O, Si, and Ce abundances based on H-band spectra taken with the multi-object APOGEE-north spectrograph from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Of the five cluster candidates, two previously unremarked stars are confirmed to have second-generation (SG) abundance patterns, with the basic pattern of depletion in C and Mg simultaneous with enrichment in N and Al as seen in other SG globular cluster populations at similar metallicity. In agreement with the most recent optical studies, the NGC 6522 stars analyzed exhibit (when available) only mild overabundances of the s-process element Ce, contradicting the idea that NGC 6522 stars are formed from gas enriched by spinstars and indicating that other stellar sources such as massive AGB stars could be the primary polluters of intra-cluster medium. The peculiar abundance signatures of SG stars have been observed in our data, confirming the presence of multiple generations of stars in NGC 6522.
    • H. pyloriinfection confers resistance to apoptosis via Brd4-dependentBIRC3eRNA synthesis

      Chen, Yanheng; Sheppard, Donald; Dong, Xingchen; Hu, Xiangming; Chen, Meihua; Chen, Ruichuan; Chakrabarti, Jayati; Zavros, Yana; Peek, Richard M., Jr.; Chen, Lin-Feng; et al. (NATURE PUBLISHING GROUP, 2020-08)
      H. pyloriinfection is one of the leading causes of gastric cancer and the pathogenicity ofH. pyloriinfection is associated with its ability to induce chronic inflammation and apoptosis resistance. WhileH. pyloriinfection-induced expression of pro-inflammatory cytokines for chronic inflammation is well studied, the molecular mechanism underlying the apoptosis resistance in infected cells is not well understood. In this study, we demonstrated thatH. pyloriinfection-induced apoptosis resistance in gastric epithelial cells triggered by Raptinal, a drug that directly activates caspase-3. This resistance resulted from the induction of cIAP2 (encoded byBIRC3) since depletion ofBIRC3by siRNA or inhibition of cIAP2 via BV6 reversedH. pylori-suppressed caspase-3 activation. The induction of cIAP2 was regulated byH. pylori-inducedBIRC3eRNA synthesis. Depletion ofBIRC3eRNA decreasedH. pylori-induced cIAP2 and reversedH. pylori-suppressed caspase-3 activation. Mechanistically,H. pyloristimulated the recruitment of bromodomain-containing factor Brd4 to the enhancer ofBIRC3and promotedBIRC3eRNA and mRNA synthesis. Inhibition of Brd4 diminished the expression ofBIRC3eRNA and the anti-apoptotic response toH. pyloriinfection. Importantly,H. pyloriisogeniccagA-deficient mutant failed to activate the synthesis ofBIRC3eRNA and the associated apoptosis resistance. Finally, in primary human gastric epithelial cells,H. pylorialso induced resistance to Raptinal-triggered caspase-3 activation by activating the Brd4-dependentBIRC3eRNA synthesis in a CagA-dependent manner. These results identify a novel function of Brd4 inH. pylori-mediated apoptosis resistance via activatingBIRC3eRNA synthesis, suggesting that Brd4 could be a potential therapeutic target forH. pylori-induced gastric cancer.
    • H.E.S.S. detection of very high-energy γ-ray emission from the quasar PKS 0736+017

      Smith, P. S.; Univ Arizona, Steward Observ (EDP SCIENCES S A, 2020-01-28)
      Context. Flat-spectrum radio-quasars (FSRQs) are rarely detected at very high energies (E& x2004;>=& x2004;100 GeV) due to their low-frequency-peaked spectral energy distributions. At present, only six FSRQs are known to emit very high-energy (VHE) photons, representing only 7% of the VHE extragalactic catalog, which is largely dominated by high-frequency-peaked BL Lacertae objects. Aims. Following the detection of MeV-GeV gamma-ray flaring activity from the FSRQ PKS 0736+017 (z& x2004;=& x2004;0.189) with Fermi-LAT, the H.E.S.S. array of Cherenkov telescopes triggered target-of-opportunity (ToO) observations on February 18, 2015, with the goal of studying the gamma-ray emission in the VHE band. Methods. H.E.S.S. ToO observations were carried out during the nights of February 18, 19, 21, and 24, 2015. Together with Fermi-LAT, the multi-wavelength coverage of the flare includes Swift observations in soft X-ray and optical-UV bands, and optical monitoring (photometry and spectro-polarimetry) by the Steward Observatory, and the ATOM, the KAIT, and the ASAS-SN telescopes. Results. VHE emission from PKS 0736+017 was detected with H.E.S.S. only during the night of February 19, 2015. Fermi-LAT data indicate the presence of a gamma-ray flare, peaking at the time of the H.E.S.S. detection, with a flux doubling timescale of around six hours. The gamma-ray flare was accompanied by at least a 1 mag brightening of the non-thermal optical continuum. No simultaneous observations at longer wavelengths are available for the night of the H.E.S.S. detection. The gamma-ray observations with H.E.S.S. and Fermi-LAT are used to put constraints on the location of the gamma-ray emitting region during the flare: it is constrained to be just outside the radius of the broad-line region r(BLR) with a bulk Lorentz factor Gamma& x2004;similar or equal to& x2004;20, or at the level of the radius of the dusty torus r(torus) with Gamma& x2004;similar or equal to& x2004;60. Conclusions. PKS 0736+017 is the seventh FSRQ known to emit VHE photons, and at z& x2004;=& x2004;0.189 is the nearest so far. The location of the gamma-ray emitting region during the flare can be tightly constrained thanks to opacity, variability, and collimation arguments.
    • H0LiCOW – X. Spectroscopic/imaging survey and galaxy-group identification around the strong gravitational lens system WFI 2033−4723

      Sluse, D; Rusu, C E; Fassnacht, C D; Sonnenfeld, A; Richard, J; Auger, M W; Coccato, L; Wong, K C; Suyu, S H; Treu, T; et al. (OXFORD UNIV PRESS, 2019-09-05)
      Galaxies and galaxy groups located along the line of sight towards gravitationally lensed quasars produce high-order perturbations of the gravitational potential at the lens position. When these perturbation are too large, they can induce a systematic error on H0 of a few per cent if the lens system is used for cosmological inference and the perturbers are not explicitly accounted for in the lens model. In this work, we present a detailed characterization of the environment of the lens system WFI 2033−4723 (⁠zsrc=1.662, zlens=0.6575), one of the core targets of the H0LiCOW project for which we present cosmological inferences in a companion paper. We use the Gemini and ESO-Very Large telescopes to measure the spectroscopic redshifts of the brightest galaxies towards the lens, and use the ESO-MUSE integral field spectrograph to measure the velocity-dispersion of the lens (⁠σlos=250+15−21  km s−1) and of several nearby galaxies. In addition, we measure photometric redshifts and stellar masses of all galaxies down to i < 23 mag, mainly based on Dark Energy Survey imaging (DR1). Our new catalogue, complemented with literature data, more than doubles the number of known galaxy spectroscopic redshifts in the direct vicinity of the lens, expanding to 116 (64) the number of spectroscopic redshifts for galaxies separated by less than 3 arcmin (2 arcmin ) from the lens. Using the flexion-shift as a measure of the amplitude of the gravitational perturbation, we identify two galaxy groups and three galaxies that require specific attention in the lens models. The ESO MUSE data enable us to measure the velocity-dispersions of three of these galaxies. These results are essential for the cosmological inference analysis presented in Rusu et al.
    • HabEx polarization ray trace and aberration analysis

      Davis, Jeffrey; Breckinridge, James B.; Chipman, Russell A.; Kupinski, Meredith K.; Univ Arizona, Coll Opt Sci (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      The flux difference between a terrestrial exoplanet and a much brighter nearby star creates an enormous optical design challenge for space-based imaging systems. Coronagraphs are designed to block the star's flux and obtain a high-dynamic-range image of the exoplanet. The contrast of an optical system is calculated using the point spread function (PSF). Contrast quantifies starlight suppression of an imaging system at a given separation of the two objects. Contrast requirements can be as small as 10 for earth-like planets. This work reports an analysis of the September 2017 Habitable Exoplanet Imaging Mission (HabEx) end-to-end optical system prescription for geometric and polarization aberrations across the 450 to 550 nm channel. The Lyot coronagraph was modeled with a vector vortex charge 6 mask but without adaptive optics (AO) to correct the phase of the Jones pupil. The detector plane irradiance was calculated for three states of the telescope/coronagraph system: (1) free of geometric and polarization aberrations; (2) isotropic mirror coatings throughout the end-to-end system; and (3) isotropic mirrors with form birefringence on the primary mirror. For each of these three states the system response both with and without a coronagraph mask was calculated. Two merit functions were defined to quantify the system's ability to attenuate starlight: (1) normalized polychromatic irradiance (NPI), and (2) starlight suppression factor (SSF). Both of these are dimensionless and their values are functions of position across the focal plane. The NPI is defined as the irradiance point-by-point across the detector plane with a coronagraph mask divided by the value of the on-axis irradiance without a coronagraph mask. The SSF is the irradiance point-by-point across the detector plane with a coronagraph mask divided by the point-by-point value of the irradiance across the detector plane without a coronagraph mask. Both the NPI and the SSF provide insights into coronagraph performance. Deviations from the aberration-free case are calculated and summarized in table 2. The conclusions are: (1) the HabEx optical system is well-balanced for both geometric and polarization aberrations; (2) the spatially dependent polarization reflectivity for the HabEx primary mirror should be specified to ensure the coating is isotropic; (3) AO to correct the two orthogonal polarization-dependent wavefront errors is essential.
    • The Habitable Exoplanet Observatory (HabEx)

      Seager, Sara; Cahoy, Kerri; Clarke, John; Domagal-Goldman, shawn; Marois, Christian; Mawet, Dimitri; Tamura, Motohide; Mouillet, David; Prusti, Timo; Robinson, Tyler; et al. (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      The Habitable-Exoplanet Observatory (HabEx) is a candidate flagship mission being studied by NASA and the astrophysics community in preparation of the 2020 Decadal Survey. The first HabEx mission concept that has been studied is a large (similar to 4m) diffraction-limited optical space telescope, providing unprecedented resolution and contrast in the optical, with extensions into the near ulttraviolet and near infrared domains. We report here on our team's efforts in defining a scientifically compelling HabEx mission that is technologically executable, affordable within NASA's expected budgetary envelope, and timely for the next decade. We also briefly discuss our plans to explore less ambitious, descoped missions relative to the primary mission architecture discussed here.
    • The Habitable Zone Planet Finder Reveals a High Mass and Low Obliquity for the Young Neptune K2-25b

      Stefansson, Gudmundur; Mahadevan, Suvrath; Maney, Marissa; Ninan, Joe P.; Robertson, Paul; Rajagopal, Jayadev; Haase, Flynn; Allen, Lori; Ford, Eric B.; Winn, Joshua; et al. (IOP PUBLISHING LTD, 2020-09-30)
      Using radial velocity data from the Habitable Zone Planet Finder, we have measured the mass of the Neptune-sized planet K2-25b, as well as the obliquity of its M4.5 dwarf host star in the 600-800 Myr Hyades cluster. This is one of the youngest planetary systems for which both of these quantities have been measured and one of the very few M dwarfs with a measured obliquity. Based on a joint analysis of the radial velocity data, time-series photometry from the K2 mission, and new transit light curves obtained with diffuser-assisted photometry, the planet's radius and mass are 3.44 +/- 0.12 R-circle plus and 24.5(-5.2)(+5.7) M-circle plus. These properties are compatible with a rocky core enshrouded by a thin hydrogen-helium atmosphere (5% by mass). We measure an orbital eccentricity of e = 0.43 +/- 0.05. The sky-projected stellar obliquity is lambda = 3 degrees +/- 16 degrees, compatible with spin-orbit alignment, in contrast to other "hot Neptunes" that have been studied around older stars.
    • The Habitable-Zone Planet Finder: improved flux image generation algorithms for H2RG up-the-ramp data

      Monson, Andrew; Stefansson, Gudmundur; Ninan, Joe P.; Bender, Chad; Mahadevan, Suvrath; Ford, Eric B.; Kaplan, Kyle F.; Terrien, Ryan C.; Roy, Arpita; Robertson, Paul; et al. (SPIE-INT SOC OPTICAL ENGINEERING, 2018)
      Noise and stability of current state of the art near-infrared (NIR) array detectors are still substantially worse than optical science grade CCDs used in astronomy. Obtaining the maximum signal-to-noise ratio in flux image is important for many NIR instruments, as is stable well understood data reduction and extraction. The Habitable-zone Planet Finder (HPF) is a near-infrared ultra stable precision radial velocity (RV) spectrograph commissioned on 10-m Hobby-Eberly Telescope (HET), McDonald Observatory, Texas, USA. HPF uses a Teledyne H2RG array detector. In order to achieve the high-precision (similar to 1 m/s) RV measurements from the NIR spectrum of HPF's science target stars, it is vital to maximize the signal-to-noise ratio and to accurately propagate the uncertainties. Here we present the algorithms we have developed to significantly improve the quality of flux images calculated from the up-the-ramp readout mode of H2RG. The algorithms in the tool HxRGproc presented in this manuscript are used for HPF's bias noise removal, non-linearity correction, cosmic ray correction, slope/flux and variance image calculation.
    • Habitat models to predict wetland bird occupancy influenced by scale, anthropogenic disturbance, and imperfect detection

      Glisson, Wesley J.; Conway, Courtney J.; Nadeau, Christopher P.; Borgmann, Kathi L.; Univ Arizona, Arizona Cooperat Fish & Wildlife Res Unit; Idaho Cooperative Fish and Wildlife Research Unit; Department of Fish & Wildlife Sciences; University of Idaho; 875 Perimeter Drive, MS 1141 Moscow Idaho 83844 USA; U.S. Geological Survey; Idaho Cooperative Fish and Wildlife Research Unit; University of Idaho; 875 Perimeter Drive, MS 1141 Moscow Idaho 83844 USA; Arizona Cooperative Fish and Wildlife Research Unit; University of Arizona; 104 Biological Sciences East Tucson Arizona 85721 USA; Arizona Cooperative Fish and Wildlife Research Unit; University of Arizona; 104 Biological Sciences East Tucson Arizona 85721 USA (WILEY, 2017-06)
      Understanding species-habitat relationships for endangered species is critical for their conservation. However, many studies have limited value for conservation because they fail to account for habitat associations at multiple spatial scales, anthropogenic variables, and imperfect detection. We addressed these three limitations by developing models for an endangered wetland bird, Yuma Ridgway's rail (Rallus obsoletus yumanensis), that examined how the spatial scale of environmental variables, inclusion of anthropogenic disturbance variables, and accounting for imperfect detection in validation data influenced model performance. These models identified associations between environmental variables and occupancy. We used bird survey and spatial environmental data at 2473 locations throughout the species' U.S. range to create and validate occupancy models and produce predictive maps of occupancy. We compared habitat-based models at three spatial scales (100, 224, and 500 m radii buffers) with and without anthropogenic disturbance variables using validation data adjusted for imperfect detection and an unadjusted validation dataset that ignored imperfect detection. The inclusion of anthropogenic disturbance variables improved the performance of habitat models at all three spatial scales, and the 224-m-scale model performed best. All models exhibited greater predictive ability when imperfect detection was incorporated into validation data. Yuma Ridgway's rail occupancy was negatively associated with ephemeral and slow-moving riverine features and high-intensity anthropogenic development, and positively associated with emergent vegetation, agriculture, and low-intensity development. Our modeling approach accounts for common limitations in modeling species-habitat relationships and creating predictive maps of occupancy probability and, therefore, provides a useful framework for other species.
    • Habitat preference of an herbivore shapes the habitat distribution of its host plant

      Alexandre, Nicolas M; Humphrey, Parris T; Gloss, Andrew D; Lee, Jimmy; Frazier, Joseph; Affeldt, Henry A; Whiteman, Noah K; Univ Arizona, Dept Ecol & Evolutionary Biol (WILEY, 2018-09)
      Plant distributions can be limited by habitat-biased herbivory, but the proximate causes of such biases are rarely known. Distinguishing plant-centric from herbivore-centric mechanisms driving differential herbivory between habitats is difficult without experimental manipulation of both plants and herbivores. Here, we tested alternative hypotheses driving habitat-biased herbivory in bittercress (Cardamine cordifolia), which is more abundant under the shade of shrubs and trees (shade) than in nearby meadows (sun) where herbivory is intense from the specialist fly Scaptomyza nigrita. This system has served as a textbook example of habitat-biased herbivory driving a plant's distribution across an ecotone, but the proximate mechanisms underlying differential herbivory are still unclear. First, we found that higher S. nigrita herbivory in sun habitats contrasts sharply with their preference to attack plants from shade habitats in laboratory-choice experiments. Second, S.nigrita strongly preferred leaves in simulated sun over simulated shade habitats, regardless of plant source habitat. Thus, herbivore preference for brighter, warmer habitats overrides their preference for more palatable shade plants. This promotes the sun-biased herbivore pressure that drives the distribution of bittercress into shade habitats.
    • Hadronic-vacuum-polarization contribution to the muon’s anomalous magnetic moment from four-flavor lattice QCD

      Davies, C. T. H.; DeTar, C.; El-Khadra, A. X.; Gámiz, E.; Gottlieb, Steven; Hatton, D.; Kronfeld, A. S.; Laiho, J.; Lepage, G. P.; Liu, Yuzhi; et al. (AMER PHYSICAL SOC, 2020-02-18)
      We calculate the contribution to the muon anomalous magnetic moment hadronic vacuum polarization from the connected diagrams of up and down quarks, omitting electromagnetism. We employ QCD gauge-field configurations with dynamical u, d, s, and c quarks and the physical pion mass, and analyze five ensembles with lattice spacings ranging from a approximate to 0.06 to 0.15 fm. The up- and down-quark masses in our simulations have equal masses m(l). We obtain, in this world where all pions have the mass of the pi(0), 10(10)a(mu)(ll)(conn.) = 637.8(8.8), in agreement with independent lattice-QCD calculations. We then combine this value with published lattice-QCD results for the connected contributions from strange, charm, and bottom quarks, and an estimate of the uncertainty due to the fact that our calculation does not include strong-isospin breaking, electromagnetism, or contributions from quark-disconnected diagrams. Our final result for the total O(alpha(2)) hadronic-vacuum polarization to the muon's anomalous magnetic moment is 10(10)a(mu)(HVP,LO) = 699(15)(u,d) (1)(s,c,b), where the errors are from the light-quark and heavy-quark contributions, respectively. Our result agrees with both ab-initio lattice-QCD calculations and phenomenological determinations from experimental e(+) e(-)-scattering data. It is 1 .3 sigma below the "no new physics" value of the hadronic-vacuum-polarization contribution inferred from combining the BNL E821 measurement of a(mu) with theoretical calculations of the other contributions.
    • Hadrons and nuclei

      Detmold, William; Edwards, Robert G.; Dudek, Jozef J.; Engelhardt, Michael; Lin, Huey-Wen; Meinel, Stefan; Orginos, Kostas; Shanahan, Phiala; Univ Arizona, Dept Phys (SPRINGER, 2019-11-14)
      In 2018, the USQCD Collaboration’s Executive Committee organized several subcommittees to recognize future opportunities and formulate possible goals for lattice field theory calculations in several physics areas. The conclusions of these studies, along with community input, are presented in seven white papers. Here, we discuss opportunities for lattice QCD calculations related to the structure and spectroscopy of hadrons and nuclei. An overview of recent lattice calculations of the structure of the proton and other hadrons is presented along with prospects for future extensions. Progress and prospects of hadronic spectroscopy and the study of resonances in the light, strange and heavy quark sectors are summarized. Finally recent advances in the study of light nuclei from lattice QCD are addressed and the scope of future investigations that are currently envisioned is outlined.
    • Hafnium Films and Magnetic Shielding for TIME, A mm-Wavelength Spectrometer Array

      Hunacek, J.; Bock, J.; Bradford, C. M.; Butler, V.; Chang, T.-C.; Cheng, Y.-T.; Cooray, A.; Crites, A.; Frez, C.; Hailey-Dunsheath, S.; et al. (SPRINGER/PLENUM PUBLISHERS, 2018-04-06)
      TIME is a mm-wavelength grating spectrometer array that will map fluctuations of the 157.7-mm emission line of singly ionized carbon ([CII]) during the epoch of reionization (redshift z similar to 5-9). Sixty transition-edge sensor (TES) bolometers populate the output arc of each of the 32 spectrometers, for a total of 1920 detectors. Each bolometer consists of gold absorber on a similar to 3 x 3 mm silicon nitride micro-mesh suspended near the corners by 1 x 1 x 500 mu m silicon nitride legs targeting a photon-noise-dominated NEP similar to 1 x 10-(17) W/root Hz. Hafnium films are explored as a lower-T-c alternative to Ti (500 mK) for TIME TESs, allowing thicker support legs for improved yield. Hf T-c is shown to vary between 250 and 450 mK when varying the resident Ar pressure during deposition. Magnetic shielding designs and simulations are presented for the TIME first-stage SQUIDs. Total axial field suppression is predicted to be 5 x 10(7).
    • The Hagiography of a Secular Saint: Alexander von Humboldt and the Scientism of the German Democratic Republic

      Howell, James F.; Univ Arizona (WILEY, 2018-02)
      Throughout its existence, the German Democratic Republic attempted to supplant religious authority and beliefs by promoting a wissenschaftliche Weltanschauung that served as a secular alternative for metaphysical frameworks of understanding and cultural orientation. An integral part of this program of substitution was the Marxist‐Leninist rehabilitation of certain members of the German canon who best embodied the socialist and scientistic potential of the German cultural tradition. As a figure who stood at the forefront of this group, Alexander von Humboldt was reimagined by the East German cultural apparatus as a “spontaneous materialist,” an educator of the masses who fought on the side of the oppressed worldwide. This analysis elucidates the ways in which the East German cultural apparatus appropriated and reconfigured Humboldt to fit its needs, as well as how, more generally, the SED designed and implemented a scientistic worldview that continues to affect and shape culture in eastern Germany today.
    • Half-Watt Tm3+-Doped Fluoride Fiber Laser at 785 nm

      Mollaee, Masoud; Zhu, Xiushan; Zong, Jie; Wiersma, Kort; Chavez-Pirson, Arturo; Norwood, R. A.; Peyghambarian, N.; Univ Arizona, Coll Opt Sci (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018-09-01)
      All-fiber single-transverse-mode laser oscillators operating at 785 nm were demonstrated by splicing a 0.1 mol% Tm3+-doped fluoride fiber with a core diameter of 4 mu m and a numerical aperture of 0.07 to a pair of silica fiber Bragg gratings. About 500 mW of continuous-wave single transverse mode laser output at 784.5 nm with a 3-dB spectral bandwidth of 0.2 nm was obtained by upconversion pumping a 3-m-long gain fiber at 1125 nm. Our experiments show that the ground-state absorption of Tm3(+ )at 785 nm is the origin of low efficiency in previous reports. The efficiency of this all-fiber laser can be improved by using a gain fiber with an optimized overlap between the laser, the pump, and the fiber core, and employing new pumping schemes that deplete the ground state sufficiently.
    • The Halo Boundary of Galaxy Clusters in the SDSS

      Baxter, Eric; Chang, Chihway; Jain, Bhuvnesh; Adhikari, Susmita; Dalal, Neal; Kravtsov, Andrey; More, Surhud; Rozo, Eduardo; Rykoff, Eli; Sheth, Ravi K.; et al. (IOP PUBLISHING LTD, 2017-05-18)
      Analytical models and simulations predict a rapid decline in the halo density profile associated with the transition from the "infalling" regime outside the halo to the "collapsed" regime within the halo. Using data from SDSS, we explore evidence for such a feature in the density profiles of galaxy clusters using several different approaches. We first estimate the steepening of the outer galaxy density profile around clusters, finding evidence for truncation of the halo profile. Next, we measure the galaxy density profile around clusters using two sets of galaxies selected on color. We find evidence of an abrupt change in galaxy colors that coincides with the location of the steepening of the density profile. Since galaxies that have completed orbits within the cluster are more likely to be quenched of star formation and thus appear redder, this abrupt change in galaxy color can be associated with the transition from single-stream to multi-stream regimes. We also use a standard model comparison approach to measure evidence for a " splashback"-like feature, but find that this approach is very sensitive to modeling assumptions. Finally, we perform measurements using an independent cluster catalog to test for potential systematic errors associated with cluster selection. We identify several avenues for future work: improved understanding of the small-scale galaxy profile, lensing measurements, identification of proxies for the halo accretion rate, and other tests. With upcoming data from the DES, KiDS, and HSC surveys, we can expect significant improvements in the study of halo boundaries.
    • Halo exclusion criteria impacts halo statistics

      García, Rafael; Rozo, Eduardo; Univ Arizona, Dept Phys (OXFORD UNIV PRESS, 2019-09-05)
      Every halo-finding algorithm must make a critical yet relatively arbitrary choice: it must decide which structures are parent haloes, and which structures are subhaloes of larger haloes. We refer to this choice as percolation. We demonstrate that the choice of percolation impacts the statistical properties of the resulting halo catalogue. Specifically, we modify the halo-finding algorithm rockstar to construct three different halo catalogues from the same simulation data, each with identical mass definitions, but different choice of percolation. The resulting haloes exhibit significant differences in both halo abundance and clustering properties. Differences in the halo mass function reach 6 per cent for haloes of mass 1013 h−1 M⊙⁠, larger than the few per cent precision necessary for current cluster abundance experiments such as the Dark Energy Survey. Comparable differences are observed in the large-scale clustering bias, while differences in the halo–matter correlation function reach 30 per cent on translinear scales. These effects can bias weak-lensing estimates of cluster masses at a level comparable to the statistical precision of current state-of-the-art experiments.
    • HALOGAS: the properties of extraplanar HI in disc galaxies

      Marasco, A.; Fraternali, F.; Heald, G.; de Blok, W. J. G.; Oosterloo, T.; Kamphuis, P.; Józsa, G. I. G.; Vargas, C. J.; Winkel, B.; Walterbos, R. A. M.; et al. (EDP SCIENCES S A, 2019-10-17)
      We present a systematic study of the extraplanar gas (EPG) in a sample of 15 nearby late-type galaxies at intermediate inclinations using publicly available, deep interferometric HI data from the Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) survey. For each system we masked the HI emission coming from the regularly rotating disc and used synthetic datacubes to model the leftover "anomalous" HI flux. Our model consists of a smooth, axisymmetric thick component described by three structural and four kinematical parameters, which are fit to the data via a Markov chain Monte Carlo (MCMC) based Bayesian method. We find that extraplanar HI is nearly ubiquitous in disc galaxies as we fail to detect it in only two of the systems with the poorest spatial resolution. The EPG component encloses similar to 5-25% of the total HI mass with a mean value of 14%, and has a typical thickness of a few kpc which is incompatible with expectations based on hydrostatic equilibrium models. The EPG kinematics is remarkably similar throughout the sample, and consists of a lagging rotation with typical vertical gradients of similar to-10 km s(-1) kpc(-1), a velocity dispersion of 15-30 km s(-1), and, for most galaxies, a global inflow in both the vertical and radial directions with speeds of 20-30 km s(-1). The EPG HI masses are in excellent agreement with predictions from simple models of the galactic fountain that are powered by stellar feedback. The combined effect of photo-ionisation and interaction of the fountain material with the circumgalactic medium can qualitatively explain the kinematics of the EPG, but dynamical models of the galactic fountain are required to fully test this framework.
    • A Hamilton-Jacobi Equation for Evaluating EEMI Propagation in a Computing System

      Valbuena, Luis; Heileman, Gregory L.; Hemmady, Sameer; Schamiloglu, Edl; Univ Arizona (IEEE, 2019-09)
      In this paper, we present a theoretical framework for modeling the empirically observed cascading of software failures on a complicated computing system exposed to extreme electromagnetic interference (EEMI). Our approach is to treat the temporal evolution of the electromagnetic coupling and the resultant cascading series of electromagnetic-induced faults as the "flow" in a dynamic fluid-mechanical system and thereby utilize aspects of the Navier Stokes and Hamilton-Jacobi equations to predict the rate of this flow. Therefore, inspired by the concepts of fluid dynamics [1], we include a diffusion term in the Hamilton-Jacobi-Isaacs (HJI) equation. We have considered two approaches. In one we apply a Taylor expansion to the optimality principle and consider additional terms; in the other scenario, we simply add a diffusion term in the form of a Laplacian applied to the cost function H(x,...) and some constant c, as it is present in the Navier-Stokes equation for incompressible flow. We provide numerical comparisons for both approaches with respect to the original HJI equation where the dynamical vector field corresponds to analytical models of a NOR logic gate. This model is a second-order differential equation that describes the behavior of the gate that incorporates a new term accounting for EEMI injection.