Now showing items 1-20 of 6512

    • Three-dimensional texture analysis of optical coherence tomography images of ovarian tissue

      Sawyer, Travis W; Chandra, Swati; Rice, Photini F S; Koevary, Jennifer W; Barton, Jennifer K; Univ Arizona, Coll Opt Sci; Univ Arizona, Dept Biomed Engn (IOP PUBLISHING LTD, 2018-12)
      Ovarian cancer has the lowest survival rate among all gynecologic cancers due to predominantly late diagnosis. Optical coherence tomography (OCT) has been applied successfully to experimentally image the ovaries in vivo; however, a robust method for analysis is still required to provide quantitative diagnostic information. Recently, texture analysis has proved to be a useful tool for tissue characterization; unfortunately, existing work in the scope of OCT ovarian imaging is limited to only analyzing 2D sub-regions of the image data, discarding information encoded in the full image area, as well as in the depth dimension. Here we address these challenges by testing three implementations of texture analysis for the ability to classify tissue type. First, we test the traditional case of extracted 2D regions of interest; then we extend this to include the entire image area by segmenting the organ from the background. Finally, we conduct a full volumetric analysis of the image volume using 3D segmented data. For each case, we compute features based on the Grey-Level Co-occurence Matrix and also by introducing a new approach that evaluates the frequency distribution in the image by computing the energy density. We test these methods on a mouse model of ovarian cancer to differentiate between age, genotype, and treatment. The results show that the 3D application of texture analysis is most effective for differentiating tissue types, yielding an average classification accuracy of 78.6%. This is followed by the analysis in 2D with the segmented image volume, yielding an average accuracy of 71.5%. Both of these improve on the traditional approach of extracting square regions of interest, which yield an average classification accuracy of 67.7%. Thus, applying texture analysis in 3D with a fully segmented image volume is the most robust approach to quantitatively characterizing ovarian tissue.
    • VECSEL Platform for Single/Dual Frequency CW Operation and Ultrashort Pulse Generation

      Laurain, A.; Rockmore, R.; Kilen, I.; Baker, C.; Scheller, M.; Addamane, S.; Balakrishnan, G.; Jones, R. J.; Koch, S. W.; Moloney, J. V.; Univ Arizona, Coll Opt Sci (IEEE, 2018)
      We present state of the art results obtained with numerically optimized VECSEL devices for the generation of multi-Watts single frequency and multi-color operation in the near infrared as well as for the direct generation of sub-100fs modelocked pulses at multi-GHz repetition rate.
    • Accelerated MR parameter mapping with a union of local subspaces constraint

      Mandava, Sagar; Keerthivasan, Mahesh B.; Li, Zhitao; Martin, Diego R.; Altbach, Maria I.; Bilgin, Ali; Univ Arizona, Dept Elect & Comp Engn; Univ Arizona, Dept Med Imaging; Univ Arizona, Dept Biomed Engn (WILEY, 2018-12)
      Purpose: A new reconstruction method for multi-contrast imaging and parameter mapping based on a union of local subspaces constraint is presented. Theory: Subspace constrained reconstructions use a predetermined subspace to explicitly constrain the relaxation signals. The choice of subspace size (K) impacts the approximation error vs noise-amplification tradeoff associated with these methods. A different approach is used in the model consistency constraint (MOCCO) framework to leverage the subspace model to enforce a softer penalty. Our proposed method, MOCCO-LS, augments the MOCCO model with a union of local subspaces (LS) approach. The union of local subspaces model is coupled with spatial support constraints and incorporated into the MOCCO framework to regularize the contrast signals in the scene. Methods: The performance of the MOCCO-LS method was evaluated in vivo on T-1 and T-2 mapping of the human brain and with Monte-Carlo simulations and compared against MOCCO and the explicit subspace constrained models. Results: The results demonstrate a clear improvement in the multi-contrast images and parameter maps. We sweep across the model order space (K) to compare the different reconstructions and demonstrate that the reconstructions have different preferential operating points. Experiments on T-2 mapping show that the proposed method yields substantial improvements in performance even when operating at very high acceleration rates. Conclusions: The use of a union of local subspace constraints coupled with a sparsity promoting penalty leads to improved reconstruction quality of multi-contrast images and parameter maps.
    • The geometry of Hida families I: Λ-adic de Rham cohomology

      Cais, Bryden; Univ Arizona, Dept Math (SPRINGER HEIDELBERG, 2018-10)
      We construct the Lambda-adic de Rham analogue of Hida's ordinary Lambda-adic etale cohomology and of Ohta's Lambda-adic Hodge cohomology, and by exploiting the geometry of integral models of modular curves over the cyclotomic extension of Qp, we give a purely geometric proof of the expected finiteness, control, and Lambda-adic duality theorems. Following Ohta, we then prove that our Lambda-adic module of differentials is canonically isomorphic to the space of ordinary Lambda-adic cuspforms. In the sequel (Cais, Compos Math, to appear) to this paper, we construct the crystalline counterpart to Hida's ordinary Lambda-adic etale cohomology, and employ integral p-adic Hodge theory to prove Lambda-adic comparison isomorphisms between all of these cohomologies. As applications of our work in this paper and (Cais, Compos Math, to appear), we will be able to provide a " cohomological" construction of the family of (phi, Gamma)-modules attached to Hida's ordinary Lambda-adic etale cohomology by Dee (J Algebra 235(2), 636664, 2001), as well as a new and purely geometric proof of Hida's finiteness and control theorems. We are also able to prove refinements of the main theorems in Mazur and Wiles (Compos Math 59(2): 231-264, 1986) and Ohta (J Reine Angew Math 463: 49-98, 1995).
    • Climatic and volcanic forcing of tropical belt northern boundary over the past 800 years

      Alfaro-Sánchez, R.; Nguyen, H.; Klesse, S.; Hudson, A.; Belmecheri, S.; Köse, N.; Diaz, H. F.; Monson, R. K.; Villalba, R.; Trouet, V.; Univ Arizona, Lab Tree Ring Res; Univ Arizona, Dept Ecol & Evolutionary Biol (NATURE PUBLISHING GROUP, 2018-12)
      The position of the northern boundary of the tropical belt affects the hydroclimate of many arid and semi-arid regions in the Northern Hemisphere. Widening of the tropical belt since the 1970s has largely been attributed to anthropogenic forcing. However, the relative influence of natural drivers of tropical belt expansion and contraction before this time is poorly understood. Here we use data on tree-ring widths from five mid-latitude regions in the Northern Hemisphere to reconstruct the movement of the northern boundary of the early spring tropical belt over the past 800 years (AD 1203-2003). Our reconstruction explains 45% of the interannual variance in the latitudinal extent of the Hadley circulation, a metric of the position of the tropical belt boundary. We find that the tropical belt contracted (expanded) during positive (negative) phases of the El Nino Southern Oscillation and Pacific North American teleconnection patterns. The tropical belt also contracted significantly following major volcanic events that injected sulfur into the stratosphere. The longest period of persistent tropical belt expansion occurred in the late sixteenth century, during one of the coldest periods of the Little Ice Age. Our results warn of potential socioeconomic consequences of future variations in tropical belt width driven by natural climate variability or stratospheric aerosol injections, whether volcanic or artificial.
    • Fourth Universal Definition of Myocardial Infarction (2018)

      Thygesen, Kristian; Alpert, Joseph S.; Jaffe, Allan S.; Chaitman, Bernard R.; Bax, Jeroen J.; Morrow, David A.; White, Harvey D.; Univ Arizona, Coll Med, Dept Med (LIPPINCOTT WILLIAMS & WILKINS, 2018-11-13)
    • Brand community coping

      Weijo, Henri; Bean, Jonathan; Rintamäki, Jukka; Univ Arizona (ELSEVIER SCIENCE INC, 2019-01)
      The successful alignment of co-creative practices between brand communities and marketers promises many benefits, including stronger consumer brand relationships. Yet recent research has identified the inherent difficulty of creating or maintaining such an alignment. This study builds on these cautionary tales to show how marketer-initiated brand transgressions impact communal brand relationships built on extensive histories of successful co-creation. Building theory through netnographic inquiry of the drama surrounding a poorly managed brand transgression in a video game brand community and a counterexample of positive marketer action, this study introduces a theoretical model of brand community coping and its four stages of instigation, distillation, mobilization, and remembrance. Overall, the study provides new insights on brand transgressions, consumer coping, brand relationships, and co-creation.
    • IGRINS Spectral Library

      Park, Sunkyung; Lee, Jeong-Eun; Kang, Wonseok; Lee, Sang-Gak; Chun, Moo-Young; Kim, Kang-Min; Yuk, In-Soo; Lee, Jae-Joon; Mace, Gregory N.; Kim, Hwihyun; Kaplan, Kyle F.; Park, Chan; Sok Oh, Jae; Lee, Sungho; Jaffe, Daniel T.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10)
      We present a library of high-resolution (R lambda/Delta lambda similar to 45,000) and high signal-to-noise ratio (S/N >= 200) near-infrared spectra for stars of a wide range of spectral types and luminosity classes. The spectra were obtained with the Immersion GRating INfrared Spectrograph covering the full range of the H (1.496-1.780 mu m) and K (2.080-2.460 mu m) atmospheric windows. The targets were primarily selected for being MK standard stars covering a wide range of effective temperatures and surface gravities, with metallicities close to the solar value. Currently, the library includes flux-calibrated and telluric-absorption-corrected spectra of 84 stars, with prospects for expansion to provide denser coverage of the parametric space. Throughout the H and K atmospheric windows, we identified spectral lines that are sensitive to T-eff or log g and defined corresponding spectral indices. We also provide their equivalent widths (EWs). For those indices, we derive empirical relations between the measured EWs and the stellar atmospheric parameters. Therefore, the derived empirical equations can be used to calculate the T-eff and log g of a star without requiring stellar atmospheric models.
    • The Arizona Radio Observatory CO Mapping Survey of Galactic Molecular Clouds. VI. The Cep OB3 Cloud (Cepheus B and C) in CO J=2-1, (CO)-C-13 J=2-1, and CO J=3-2

      Bieging, John H.; Patel, Saahil; Hofmann, Ryan; Peters, William L.; Kainulainen, Jouni; Zhang, Miaomiao; Stutz, Amelia M.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10)
      We present (1) new fully sampled maps of CO and (CO)-C-13 J = 2-1 emission and CO J = 3-2 emission toward the molecular clouds Cep B and C, associated with the Cep OB3 association; (2) a map of extinction, A(V), derived from IR colors of background stars; and (3) the distribution of young stellar objects (YSOs) over the same field as the molecular maps. An LTE analysis of the CO and (CO)-C-13. maps yields the distribution of molecular column densities and temperatures. Substantial variations are evident across the clouds; smaller subregions show correlations between molecular properties and dust extinction, consistent with a picture of outer photodissociation regions with a layer of CO-dark molecular gas, a CO self-shielded interior, and an inner cold dense region where CO is largely depleted onto grains. Comparing the distribution of YSOs with molecular gas surface density shows a power-law relation very similar in slope to that for the giant molecular cloud associated with the H II region Sh2-235 from a previous paper in this series that employed the same methodology. We note the presence of several compact, isolated CO emission sources in the J = 3-2 maps. The gas temperature and (CO)-C-13. velocity dispersion yield a map of the sonic Mach number, which varies across the cloud but always exceeds unity, confirming the pervasiveness of supersonic turbulence over length scales greater than or similar to 0.1 pc (the map resolution). We also compute a J = 2-1 CO X-factor that varies with position but is, on average, within. 20% of the Galactic average derived from CO J = 1-0 observations.
    • Emission Line Ratios for the Circumgalactic Medium and the “Bimodal” Nature of Galaxies

      Zhang, Huanian; Zaritsky, Dennis; Werk, Jessica; Behroozi, Peter; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-10)
      We find significantly different diagnostic emission line ratios for the circumgalactic gas associated with galaxies of stellar masses above and below 10(10.4)M(circle dot) using Sloan Digital Sky Survey spectroscopy. Specifically, in a sample of 17,393 galaxies, intersected by 18,535 lines of sight at projected radii between 10 and 50 kpc, we stack measured fluxes for nebular strong emission lines, [O III] lambda 5007, H alpha, and [N II] lambda 6583, and find that the gas surrounding the lower-mass galaxies exhibits similar line ratios to those of gas ionized by star formation and that surrounding the higher-mass galaxies similar to those of gas ionized by active galactic nucleus or shocks. This finding highlights yet another characteristic of galaxies that is distinctly different above and below this stellar mass threshold, but one that is more closely connected to the gas accretion behavior hypothesized to be responsible for this dichotomy.
    • Evidence for Ultra-diffuse Galaxy “Formation” through Galaxy Interactions

      Bennet, P.; Sand, D. J.; Zaritsky, D.; Crnojević, D.; Spekkens, K.; Karunakaran, A.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-10)
      We report the discovery of two ultra-diffuse galaxies (UDGs) that show clear evidence of an association with tidal material and an interaction with a larger galaxy halo, found during a search of the Wide portion of the Canada-France-Hawaii Telescope Legacy Survey. The two new UDGs, NGC 2708-Dw1 and NGC 5631-Dw1, are faint (M-g = -13.7 and -11.8 mag), extended (r(h) = 2.60 and 2.15 kpc), and have low central surface brightness (mu(g, 0) = 24.9 and 27.3 mag arcsec(-2)), while the stellar stream associated with each has a surface brightness mu(g) greater than or similar to 28.2 mag arcsec(-2). These observations provide evidence that the origin of some UDGs may connect to galaxy interactions, either by transforming normal dwarf galaxies by expanding them, or because UDGs can collapse out of tidal material (i.e., they are tidal dwarf galaxies). Further work is needed to understand the fraction of the UDG population "formed" through galaxy interactions, and wide field searches for diffuse dwarf galaxies will provide further clues to the origin of these enigmatic stellar systems.
    • Resolved Kinematics of Runaway and Field OB Stars in the Small Magellanic Cloud

      Oey, M. S.; Jones, J. Dorigo; Castro, N.; Zivick, P.; Besla, G.; Januszewski, H. C.; Moe, M.; Kallivayalil, N.; Lennon, D. J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-11-01)
      We use Gaia Data Release 2 proper motions of field OB stars from the Runaways and Isolated O-Type Star Spectroscopic Survey of the Small Magellanic Cloud (SMC) to study the kinematics of runaway stars. The data reveal that the SMC Wing has a systemic peculiar motion relative to the SMC Bar of (v(alpha), v(delta)) = (62 +/- 7, -18 +/- 5) km s(-1) and relative radial velocity +4.5 +/- 5.0 km s(-1). This unambiguously demonstrates that these two regions are kinematically distinct: the Wing is moving away from the Bar, and towards the Large Magellanic Cloud with a 3D velocity of 64 +/- 10 km s(-1). This is consistent with models for a recent, direct collision between the Clouds. We present transverse velocity distributions for our field OB stars, confirming that unbound runaways comprise on the order of half our sample, possibly more. Using eclipsing binaries and double-lined spectroscopic binaries as tracers of dynamically ejected runaways, and high-mass X-ray binaries (HMXBs) as tracers of runaways accelerated by supernova kicks, we find significant contributions from both populations. The data suggest that HMXBs have lower velocity dispersion relative to dynamically ejected binaries, consistent with the former group corresponding to less energetic supernova kicks that failed to unbind the components. Evidence suggests that our fast runaways are dominated by dynamical, rather than supernova, ejections.
    • Global-mean Vertical Tracer Mixing in Planetary Atmospheres. I. Theory and Fast-rotating Planets

      Zhang, Xi; Showman, Adam P.; Univ Arizona, Dept Planetary Sci; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-10-10)
      Most chemistry and cloud formation models for planetary atmospheres adopt a one-dimensional (1D) diffusion approach to approximate the global-mean vertical tracer transport. The physical underpinning of the key parameter in this framework, eddy diffusivity K-zz, is usually obscure. Here we analytically and numerically investigate vertical tracer transport in a 3D stratified atmosphere and predict K-zz as a function of the large-scale circulation strength, horizontal mixing due to eddies and waves and local tracer sources and sinks We find that K-zz increases with tracer chemical lifetime and circulation strength but decreases with horizontal eddy mixing efficiency. We demarcated three K-zz regimes in planetary atmospheres. In the first regime where the tracer lifetime is short compared with the transport timescale and horizontal tracer distribution under chemical equilibrium (chi(0)) is uniformly distributed across the globe, global-mean vertical tracer mixing behaves diffusively. But the traditional assumption in current 1D models that all chemical species are transported via the same eddy diffusivity generally breaks down. We show that different chemical species in a single atmosphere should in principle have different eddy diffusion profiles. In the second regime where the tracer is short-lived but chi(0) is non-uniformly distributed, a significant non-diffusive component might lead to a negative K-zz under the diffusive assumption. In the third regime where the tracer is long-lived, global-mean vertical tracer transport is also largely influenced by non-diffusive effects. Numerical simulations of 2D tracer transport on fast-rotating zonally symmetric planets validate our analytical K-zz theory over a wide parameter space.
    • Global-mean Vertical Tracer Mixing in Planetary Atmospheres. II. Tidally Locked Planets

      Zhang, Xi; Showman, Adam P.; Univ Arizona, Dept Planetary Sci; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-10-10)
      In Zhang & Showman, we developed an analytical theory of 1D eddy diffusivity K-zz for global-mean vertical tracer transport in a 3D atmosphere. We also presented 2D numerical simulations on fast-rotating planets to validate our theory. On a slowly rotating planet such as Venus or a tidally locked planet (not necessarily a slow-rotator) such as a hot Jupiter, the tracer distribution could exhibit significant longitudinal inhomogeneity and tracer transport is intrinsically 3D. Here we study the global-mean vertical tracer transport on tidally locked planets using 3D tracer-transport simulations. We find that our analytical K-zz theory in Zhang & Showman is validated on tidally locked planets over a wide parameter space. K-zz strongly depends on the large-scale circulation strength, horizontal mixing due to eddies, and waves, and local tracer sources and sinks due to chemistry and microphysics. As our analytical theory predicted, K-zz on tidally locked planets also exhibit three regimes. In Regime I where the chemical and microphysical processes are uniformly distributed across the globe, different chemical species should be transported via different eddy diffusivity. In Regime II where the chemical and microphysical processes are nonuniform-for example, photochemistry or cloud formation that exhibits strong day-night contrast-the global-mean vertical tracer mixing does not always behave diffusively. In the third regime where the tracer is long-lived, non-diffusive effects are significant. Using species-dependent eddy diffusivity, we provide a new analytical theory of the dynamical quench points for disequilibrium tracers on tidally locked planets from first principles.
    • Extremely Irradiated Hot Jupiters: Non-oxide Inversions, H- Opacity, and Thermal Dissociation of Molecules

      Lothringer, Joshua D.; Barman, Travis; Koskinen, Tommi; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2018-10-10)
      Extremely irradiated hot Jupiters, exoplanets reaching dayside temperatures >2000 K, stretch our understanding of planetary atmospheres and the models we use to interpret observations. While these objects are planets in every other sense, their atmospheres reach temperatures at low pressures comparable only to stellar atmospheres. In order to understand our a priori theoretical expectations for the nature of these objects, we self-consistently model a number of extreme hot Jupiter scenarios with the PHOENIX model atmosphere code. PHOENIX is well-tested on objects from cool brown dwarfs to expanding supernovae shells, and its expansive opacity database from the UV to far-IR make PHOENIX well-suited to understanding extremely irradiated hot Jupiters. We find several fundamental differences between hot Jupiters at temperatures >2500 K and their cooler counterparts. First, absorption by atomic metals like Fe and Mg, molecules including SiO and metal hydrides, and continuous opacity sources like H-, all combined with the short-wavelength output of early-type host stars, result in strong thermal inversions, without the need for TiO or VO. Second, many molecular species, including H2O, TiO, and VO are thermally dissociated at pressures probed by transit and eclipse observations, potentially biasing retrieval algorithms that assume uniform vertical abundances. We discuss other interesting properties of these objects, as well as future prospects and predictions for observing and characterizing this unique class of astrophysical object, including the first self-consistent model of the hottest known Jovian planet, KELT-9b.
    • The MOSDEF Survey: The Nature of Mid-infrared Excess Galaxies and a Comparison of IR and UV Star Formation Tracers at z ∼ 2

      Azadi, Mojegan; Coil, Alison; Aird, James; Shivaei, Irene; Reddy, Naveen; Shapley, Alice; Kriek, Mariska; Freeman, William R.; Leung, Gene C. K.; Mobasher, Bahram; Price, Sedona H.; Sanders, Ryan L.; Siana, Brian; Zick, Tom; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-10)
      We present an analysis using the MOSFIRE Deep Evolution Field (MOSDEF) survey on the nature of "MIR-excess" galaxies, which have star formation rates (SFRs) inferred from mid-infrared (MIR) data that are substantially elevated relative to those estimated from dust-corrected UV data. We use a sample of similar to 200 galaxies and active galactic nuclei (AGNs) at 1.40 < z < 2.61 with 24 mu m detections (rest-frame 8 mu m) from MIPS/Spitzer. We find that the identification of MIR-excess galaxies strongly depends on the methodologies used to estimate IR luminosity (L-IR) and to correct the UV light for dust attenuation. We find that extrapolations of the SFR from the observed 24 mu m flux, using luminosity-dependent templates based on local galaxies, substantially overestimate L-IR in z similar to 2 galaxies. By including Herschel observations and using a stellar-mass-dependent, luminosity-independent L-IR, we obtain more reliable estimates of the SFR and a lower fraction of MIR-excess galaxies. Once stellar-mass selection biases are taken into account, we identify similar to 24% of our galaxies as MIR excess. However, SFRH alpha is not elevated in MIR-excess galaxies compared to MIR-normal galaxies, indicating that the intrinsic fraction of MIR excess may be lower. Using X-ray-, IR-, and optically selected AGNs in MOSDEF, we do not find a higher prevalence for AGNs in MIR-excess galaxies relative to MIR-normal galaxies. A stacking analysis of X-ray-undetected galaxies does not reveal a harder spectrum in MIR-excess galaxies relative to MIR-normal galaxies. Our analysis indicates that AGN activity does not contribute substantially to the MIR excess and instead implies that it is likely due to the enhanced polycyclic aromatic hydrocarbon emission.
    • Dust Emission in an Accretion-rate-limited Sample of z ≳ 6 Quasars

      Venemans, Bram P.; Decarli, Roberto; Walter, Fabian; Bañados, Eduardo; Bertoldi, Frank; Fan, Xiaohui; Farina, Emanuele Paolo; Mazzucchelli, Chiara; Riechers, Dominik; Rix, Hans-Walter; Wang, Ran; Yang, Yujin; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present Atacama Large Millimeter Array 1 mm observations of the rest-frame far-infrared (FIR) dust continuum in 27 quasars at redshifts 6.0 less than or similar to z < 6.7. We detect FIR emission at greater than or similar to 3 sigma in all quasar host galaxies with flux densities at similar to 1900 GHz in the rest-frame of 0.12 < S-rest,S- (1900) (GHz) < 5.9 mJy, with a median (mean) flux density of 0.88 mJy (1.59 mJy). The implied FIR luminosities range from L-FIR = (0.27-13) x 10(12) L-circle dot, with 74% of our quasar hosts having L-FIR > 10(12) L-circle dot The estimated dust masses are M-dust = 10(7)-10(9) M-circle dot. If the dust is heated only by star formation, then the star formation rates in the quasar host galaxies are between 50 and 2700 M-circle dot yr(-1). In the framework of the host galaxy-black hole coevolution model a correlation between ongoing black hole growth and star formation in the quasar host galaxy would be expected. However, combined with results from the literature to create a luminosity-limited quasar sample, we do not find a strong correlation between quasar UV luminosity (a proxy for ongoing black hole growth) and FIR luminosity (star formation in the host galaxy). The absence of such a correlation in our data does not necessarily rule out the coevolution model, and could be due to a variety of effects (including different timescales for black hole accretion and FIR emission).
    • The VLA Nascent Disk and Multiplicity Survey of Perseus Protostars (VANDAM). V. 18 Candidate Disks around Class 0 and I Protostars in the Perseus Molecular Cloud

      Segura-Cox, Dominique M.; Looney, Leslie W.; Tobin, John J.; Li, Zhi-Yun; Harris, Robert J.; Sadavoy, Sarah; Dunham, Michael M.; Chandler, Claire; Kratter, Kaitlin; Pérez, Laura; Melis, Carl; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present the full disk-fit results VANDAM survey of all Class 0 and I protostars in the Perseus molecular cloud. We have 18 new protostellar disk candidates around Class 0 and I sources, which are well described by a simple, parametrized disk model fit to the 8 mm VLA dust continuum observations. 33% of Class 0 protostars and just 11% of Class I protostars have candidate disks, while 78% of Class 0 and I protostars do not have signs of disks within our 12 au disk diameter resolution limit, indicating that at 8 mm most disks in the Class 0 and I phases are <10 au in radius. These small radii may be a result of surface brightness sensitivity limits. Modeled 8 mm radii are similar to the radii of known Class 0 disks with detected Keplerian rotation. Since our 8 mm data trace a population of larger dust grains that radially drift toward the protostar and are lower limits on true disk sizes, large disks at early times do not seem to be particularly rare. We find statistical evidence that Class 0 and I disks are likely drawn from the same distribution, meaning disk properties may be defined early in the Class 0 phase and do not undergo large changes through the Class I phase. By combining our candidate disk properties with previous polarization observations, we find a qualitative indication that misalignment between inferred envelope-scale magnetic fields and outflows may indicate disks on smaller scales in Class 0 sources.
    • Polar Dust, Nuclear Obscuration, and IR SED Diversity in Type-1 AGNs

      Lyu, Jianwei; Rieke, George H.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      Despite the hypothesized similar face-on viewing angles, the infrared emission of type-1 active galactic nuclei (AGNs) has diverse spectral energy distribution (SED) shapes that deviate substantially from the well-characterized quasar templates. Motivated by the commonly seen UV-optical obscuration and the discovery of parsec-scale mid-IR polar dust emission in some nearby AGNs, we develop semi-empirical SED libraries for reddened type-1 AGNs built on quasar intrinsic templates, assuming low-level extinction caused by an extended distribution of large dust grains. We demonstrate that this model can reproduce the nuclear UV to IR SED and the strong mid-IR polar dust emission of NGC 3783, the type-1 AGN with the most relevant and robust observational constraints. In addition, we compile 64 low-z Seyfert-1 nuclei with negligible mid-IR star formation contamination and satisfactorily fit the individual IR SEDs as well as the composite UV to mid-IR composite SEDs. Given the success of these fits, we characterize the possible infrared SED of AGN polar dust emission and utilize a simple but effective strategy to infer its prevalence among type-1 AGNs. The SEDs of high-z peculiar AGNs, including the extremely red quasars, mid-IR warm-excess AGNs, and hot dust-obscured galaxies, can be also reproduced by our model. These results indicate that the IR SEDs of most AGNs, regardless of redshift or luminosity, arise from similar circumnuclear torus properties but differ mainly due to the optical depths of extended obscuring dust components.
    • Velocity-resolved Reverberation Mapping of Five Bright Seyfert 1 Galaxies

      De Rosa, G.; Fausnaugh, M. M.; Grier, C. J.; Peterson, B. M.; Denney, K. D.; Horne, Keith; Bentz, M. C.; Ciroi, S.; Bontà, E. Dalla; Joner, M. D.; Kaspi, S.; Kochanek, C. S.; Pogge, R. W.; Sergeev, S. G.; Vestergaard, M.; Adams, S. M.; Antognini, J.; Salvo, C. Araya; Armstrong, E.; Bae, J.; Barth, A. J.; Beatty, T. G.; Bhattacharjee, A.; Borman, G. A.; Boroson, T. A.; Bottorff, M. C.; Brown, J. E.; Brown, J. S.; Brotherton, M. S.; Coker, C. T.; Clanton, C.; Cracco, V.; Crawford, S. M.; Croxall, K. V.; Eftekharzadeh, S.; Eracleous, M.; Fiorenza, S. L.; Frassati, A.; Hawkins, K.; Henderson, C. B.; Holoien, T. W.-S.; Hutchison, T.; Kellar, J.; Kilerci-Eser, E.; Kim, S.; King, A. L.; Mura, G. La; Laney, C. D.; Li, M.; Lochhaas, C.; Ma, Z.; MacInnis, F.; Manne-Nicholas, E. R.; Mason, M.; McGraw, S. M.; Mogren, K.; Montouri, C.; Moody, J. W.; Mosquera, A. M.; Mudd, D.; Musso, R.; Nazarov, S. V.; Nguyen, M. L.; Ochner, P.; Okhmat, D. N.; Onken, C. A.; Ou-Yang, B.; Pancoast, A.; Pei, L.; Penny, M.; Poleski, R.; Portaluri, E.; Prieto, J.-L.; Price-Whelan, A. M.; Pulatova, N. G.; Rafter, S.; Roettenbacher, R. M.; Romero-Colmenero, E.; Runnoe, J.; Schimoia, J. S.; Shappee, B. J.; Sherf, N.; Simonian, G. V.; Siviero, A.; Skowron, D. M.; Skowron, J.; Somers, G.; Spencer, M.; Starkey, D. A.; Stevens, D. J.; Stoll, R.; Tamajo, E.; Tayar, J.; Saders, J. L. van; Valenti, S.; Villanueva, Jr., S.; Villforth, C.; Weiss, Y.; Winkler, H.; Zastrow, J.; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2018-10-20)
      We present the first results from a reverberation-mapping campaign undertaken during the first half of 2012, with additional data on one active galactic nucleus (AGN) (NGC 3227) from a 2014 campaign. Our main goals are (1) to determine the black hole masses from continuum-H beta reverberation signatures, and (2) to look for velocity-dependent time delays that might be indicators of the gross kinematics of the broad-line region. We successfully measure H beta time delays and black hole masses for five AGNs, four of which have previous reverberation mass measurements. The values measured here are in agreement with earlier estimates, though there is some intrinsic scatter beyond the formal measurement errors. We observe velocity-dependent H beta lags in each case, and find that the patterns have changed in the intervening five years for three AGNs that were also observed in 2007.