Lenses in the forest: cross correlation of the Lyman-alpha flux with cosmic microwave background lensing.

Science.gov (United States)

Vallinotto, Alberto; Das, Sudeep; Spergel, David N; Viel, Matteo

2009-08-28

We present a theoretical estimate for a new observable: the cross correlation between the Lyman-alpha flux fluctuations in quasar spectra and the convergence of the cosmic microwave background as measured along the same line of sight. As a first step toward the assessment of its detectability, we estimate the signal-to-noise ratio using linear theory. Although the signal-to-noise is small for a single line of sight and peaks at somewhat smaller redshifts than those probed by the Lyman-alpha forest, we estimate a total signal-to-noise of 9 for cross correlating quasar spectra of SDSS-III with Planck and 20 for cross correlating with a future polarization based cosmic microwave background experiment. The detection of this effect would be a direct measure of the neutral hydrogen-matter cross correlation and could provide important information on the growth of structures at large scales in a redshift range which is still poorly probed.

HERSCHEL-ATLAS: TOWARD A SAMPLE OF {approx}1000 STRONGLY LENSED GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Gonzalez-Nuevo, J.; Lapi, A.; Bressan, S.; Danese, L.; De Zotti, G.; Cai, Z.-Y.; Fan, L. [SISSA, Via Bonomea 265, I-34136 Trieste (Italy); Fleuren, S.; Sutherland, W. [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Negrello, M. [Department of Physical Sciences, Open University, Milton Keynes MK7 6AA (United Kingdom); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854-8019 (United States); Clements, D. L. [Astrophysics Group, Imperial College, Blackett Lab, Prince Consort Road, London SW7 2AZ (United Kingdom); Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Dannerbauer, H. [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, 1180 Wien, Oesterreich (Austria); Dunne, L.; Dye, S. [School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom); Eales, S. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Frayer, D. T. [National Radio Astronomy Observatory, P.O. Box 2, Green Bank, WV 24944 (United States); Harris, A. I., E-mail: gnuevo@sissa.it [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); and others

2012-04-10

While the selection of strongly lensed galaxies (SLGs) with 500 {mu}m flux density S{sub 500} > 100 mJy has proven to be rather straightforward, for many applications it is important to analyze samples larger than the ones obtained when confining ourselves to such a bright limit. Moreover, only by probing to fainter flux densities is it possible to exploit strong lensing to investigate the bulk of the high-z star-forming galaxy population. We describe HALOS (the Herschel-ATLAS Lensed Objects Selection), a method for efficiently selecting fainter candidate SLGs, reaching a surface density of {approx_equal} 1.5-2 deg{sup -2}, i.e., a factor of about 4-6 higher than that at the 100 mJy flux limit. HALOS will allow the selection of up to {approx}1000 candidate SLGs (with amplifications {mu} {approx}> 2) over the full H-ATLAS survey area. Applying HALOS to the H-ATLAS Science Demonstration Phase field ({approx_equal} 14.4 deg{sup 2}) we find 31 candidate SLGs, whose candidate lenses are identified in the VIKING near-infrared catalog. Using the available information on candidate sources and candidate lenses we tentatively estimate a {approx_equal} 72% purity of the sample. As expected, the purity decreases with decreasing flux density of the sources and with increasing angular separation between candidate sources and lenses. The redshift distribution of the candidate lensed sources is close to that reported for most previous surveys for lensed galaxies, while that of candidate lenses extends to redshifts substantially higher than found in the other surveys. The counts of candidate SLGs are also in good agreement with model predictions. Even though a key ingredient of the method is the deep near-infrared VIKING photometry, we show that H-ATLAS data alone allow the selection of a similarly deep sample of candidate SLGs with an efficiency close to 50%; a slightly lower surface density ({approx_equal} 1.45 deg{sup -2}) can be reached with a {approx}70% efficiency.

Strong field gravitational lensing by a charged Galileon black hole

Energy Technology Data Exchange (ETDEWEB)

Zhao, Shan-Shan; Xie, Yi, E-mail: clefairy035@163.com, E-mail: yixie@nju.edu.cn [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)

2016-07-01

Strong field gravitational lensings are dramatically disparate from those in the weak field by representing relativistic images due to light winds one to infinity loops around a lens before escaping. We study such a lensing caused by a charged Galileon black hole, which is expected to have possibility to evade no-hair theorem. We calculate the angular separations and time delays between different relativistic images of the charged Galileon black hole. All these observables can potentially be used to discriminate a charged Galileon black hole from others. We estimate the magnitudes of these observables for the closest supermassive black hole Sgr A*. The strong field lensing observables of the charged Galileon black hole can be close to those of a tidal Reissner-Nordström black hole or those of a Reissner-Nordström black hole. It will be helpful to distinguish these black holes if we can separate the outermost relativistic images and determine their angular separation, brightness difference and time delay, although it requires techniques beyond the current limit.

The Faint End of the Lyman Alpha Luminosity Function at 2 < z < 3.8

Science.gov (United States)

Devarakonda, Yaswant; Livermore, Rachael; Indahl, Briana; Wold, Isak; Davis, Dustin; Finkelstein, Steven

2018-01-01

Most current models predict that our universe is mostly composed of small, dim galaxies. Due to these galaxies being so faint, it is very difficult to study these types of galaxies outside of our local universe. This is particularly an issue for studying how these small galaxies evolved over their lifetimes. With the benefit of gravitational lensing, however, we are able to observe galaxies that are farther and fainter than ever before possible. In this particular study, we focus on Lyman-Alpha emitting galaxies between the redshifts of 2-3.8, so that we may study these galaxies during the epoch of peak star formation in the universe. We use the McDonald Observatory 2.7, Harlan Smith telescope with the VIRUS-P IFU spectrograph to observe several Hubble Frontier Field lensing clusters to spectroscopically discover faint galaxies over this redshift range. In addition to providing insight into the faint-end slope of the Lyman alpha luminosity function, the spectroscopic redshifts will allow us to better constrain the mass models of the foreground clusters, such as Abell 370, so that we may better understand lensing effects for this and future studies.

Strong lensing of gravitational waves as seen by LISA.

Science.gov (United States)

Sereno, M; Sesana, A; Bleuler, A; Jetzer, Ph; Volonteri, M; Begelman, M C

2010-12-17

We discuss strong gravitational lensing of gravitational waves from the merging of massive black hole binaries in the context of the LISA mission. Detection of multiple events would provide invaluable information on competing theories of gravity, evolution and formation of structures and, possibly, constraints on H0 and other cosmological parameters. Most of the optical depth for lensing is provided by intervening massive galactic halos, for which wave optics effects are negligible. Probabilities to observe multiple events are sizable for a broad range of formation histories. For the most optimistic models, up to ≲ 4 multiple events with a signal to noise ratio ≳ 8 are expected in a 5-year mission. Chances are significant even for conservative models with either light (≲ 60%) or heavy (≲ 40%) seeds. Because of lensing amplification, some intrinsically too faint signals are brought over threshold (≲ 2 per year).

Strong deflection gravitational lensing by a modified Hayward black hole

Energy Technology Data Exchange (ETDEWEB)

Zhao, Shan-Shan; Xie, Yi [Nanjing University, School of Astronomy and Space Science, Nanjing (China); Nanjing University, Ministry of Education, Key Laboratory of Modern Astronomy and Astrophysics, Nanjing (China)

2017-05-15

A modified Hayward black hole is a nonsingular black hole. It is proposed that it would form when the pressure generated by quantum gravity can stop matter's collapse as the matter reaches the Planck density. Strong deflection gravitational lensing occurring nearby its event horizon might provide some clues of these quantum effects in its central core. We investigate observables of the strong deflection lensing, including angular separations, brightness differences and time delays between its relativistic images, and we estimate their values for the supermassive black hole in the Galactic center. We find that it is possible to distinguish the modified Hayward black hole from a Schwarzschild one, but it demands a very high resolution, beyond current stage. (orig.)

Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

Science.gov (United States)

Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

2017-03-03

We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4}  s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.

The Sloan Lens ACS Survey. XIII. Discovery of 40 New Galaxy-scale Strong Lenses

Science.gov (United States)

Shu, Yiping; Brownstein, Joel R.; Bolton, Adam S.; Koopmans, Léon V. E.; Treu, Tommaso; Montero-Dorta, Antonio D.; Auger, Matthew W.; Czoske, Oliver; Gavazzi, Raphaël; Marshall, Philip J.; Moustakas, Leonidas A.

2017-12-01

We present the full sample of 118 galaxy-scale strong-lens candidates in the Sloan Lens ACS (SLACS) Survey for the Masses (S4TM) Survey, which are spectroscopically selected from the final data release of the Sloan Digital Sky Survey. Follow-up Hubble Space Telescope (HST) imaging observations confirm that 40 candidates are definite strong lenses with multiple lensed images. The foreground-lens galaxies are found to be early-type galaxies (ETGs) at redshifts 0.06–0.44, and background sources are emission-line galaxies at redshifts 0.22–1.29. As an extension of the SLACS Survey, the S4TM Survey is the first attempt to preferentially search for strong-lens systems with relatively lower lens masses than those in the pre-existing strong-lens samples. By fitting HST data with a singular isothermal ellipsoid model, we find that the total projected mass within the Einstein radius of the S4TM strong-lens sample ranges from 3 × 1010 M ⊙ to 2 × 1011 M ⊙. In Shu et al., we have derived the total stellar mass of the S4TM lenses to be 5 × 1010 M ⊙ to 1 × 1012 M ⊙. Both the total enclosed mass and stellar mass of the S4TM lenses are on average almost a factor of 2 smaller than those of the SLACS lenses, which also represent the typical mass scales of the current strong-lens samples. The extended mass coverage provided by the S4TM sample can enable a direct test, with the aid of strong lensing, for transitions in scaling relations, kinematic properties, mass structure, and dark-matter content trends of ETGs at intermediate-mass scales as noted in previous studies. Based on observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. These observations are associated with HST program #12210.

Strong gravitational lensing by a Konoplya-Zhidenko rotating non-Kerr compact object

Energy Technology Data Exchange (ETDEWEB)

Wang, Shangyun; Chen, Songbai; Jing, Jiliang, E-mail: shangyun_wang@163.com, E-mail: csb3752@hunnu.edu.cn, E-mail: jljing@hunnu.edu.cn [Institute of Physics and Department of Physics, Hunan Normal University, Changsha, Hunan 410081 (China)

2016-11-01

Konoplya and Zhidenko have proposed recently a rotating non-Kerr black hole metric beyond General Relativity and make an estimate for the possible deviations from the Kerr solution with the data of GW 150914. We here study the strong gravitational lensing in such a rotating non-Kerr spacetime with an extra deformation parameter. We find that the condition of existence of horizons is not inconsistent with that of the marginally circular photon orbit. Moreover, the deflection angle of the light ray near the weakly naked singularity covered by the marginally circular orbit diverges logarithmically in the strong-field limit. In the case of the completely naked singularity, the deflection angle near the singularity tends to a certain finite value, whose sign depends on the rotation parameter and the deformation parameter. These properties of strong gravitational lensing are different from those in the Johannsen-Psaltis rotating non-Kerr spacetime and in the Janis-Newman-Winicour spacetime. Modeling the supermassive central object of the Milk Way Galaxy as a Konoplya-Zhidenko rotating non-Kerr compact object, we estimated the numerical values of observables for the strong gravitational lensing including the time delay between two relativistic images.

Testing the Speed of Gravitational Waves over Cosmological Distances with Strong Gravitational Lensing.

Science.gov (United States)

Collett, Thomas E; Bacon, David

2017-03-03

Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al. [J. Cosmol. Astropart. Phys.10 (2014) 080JCAPBP1475-751610.1088/1475-7516/2014/10/080] forecast that 50-100 strongly lensed GW events will be observed each year with the Einstein Telescope. A single strongly lensed GW event would produce robust constraints on c_{GW}/c_{γ} at the 10^{-7} level, if a high-energy EM counterpart is observed within the field of view of an observing γ-ray burst monitor.

Simulation-based marginal likelihood for cluster strong lensing cosmology

Science.gov (United States)

Killedar, M.; Borgani, S.; Fabjan, D.; Dolag, K.; Granato, G.; Meneghetti, M.; Planelles, S.; Ragone-Figueroa, C.

2018-01-01

Comparisons between observed and predicted strong lensing properties of galaxy clusters have been routinely used to claim either tension or consistency with Λ cold dark matter cosmology. However, standard approaches to such cosmological tests are unable to quantify the preference for one cosmology over another. We advocate approximating the relevant Bayes factor using a marginal likelihood that is based on the following summary statistic: the posterior probability distribution function for the parameters of the scaling relation between Einstein radii and cluster mass, α and β. We demonstrate, for the first time, a method of estimating the marginal likelihood using the X-ray selected z > 0.5 Massive Cluster Survey clusters as a case in point and employing both N-body and hydrodynamic simulations of clusters. We investigate the uncertainty in this estimate and consequential ability to compare competing cosmologies, which arises from incomplete descriptions of baryonic processes, discrepancies in cluster selection criteria, redshift distribution and dynamical state. The relation between triaxial cluster masses at various overdensities provides a promising alternative to the strong lensing test.

Relationship between high-energy absorption cross section and strong gravitational lensing for black hole

International Nuclear Information System (INIS)

Wei Shaowen; Liu Yuxiao; Guo Heng

2011-01-01

In this paper, we obtain a relation between the high-energy absorption cross section and the strong gravitational lensing for a static and spherically symmetric black hole. It provides us a possible way to measure the high-energy absorption cross section for a black hole from strong gravitational lensing through astronomical observation. More importantly, it allows us to compute the total energy emission rate for high-energy particles emitted from the black hole acting as a gravitational lens. It could tell us the range of the frequency, among which the black hole emits the most of its energy and the gravitational waves are most likely to be observed. We also apply it to the Janis-Newman-Winicour solution. The results suggest that we can test the cosmic censorship hypothesis through the observation of gravitational lensing by the weakly naked singularities acting as gravitational lenses.

Can strong gravitational lensing constrain dark energy?

International Nuclear Information System (INIS)

Lee, Seokcheon; Ng, K.-W.

2007-01-01

We discuss the ratio of the angular diameter distances from the source to the lens, D ds , and to the observer at present, D s , for various dark energy models. It is well known that the difference of D s s between the models is apparent and this quantity is used for the analysis of Type Ia supernovae. However we investigate the difference between the ratio of the angular diameter distances for a cosmological constant, (D ds /D s ) Λ , and that for other dark energy models, (D ds /D s ) other , in this paper. It has been known that there is lens model degeneracy in using strong gravitational lensing. Thus, we investigate the model independent observable quantity, Einstein radius (θ E ), which is proportional to both D ds /D s and velocity dispersion squared, σ v 2 . D ds /D s values depend on the parameters of each dark energy model individually. However, (D ds /D s ) Λ -(D ds /D s ) other for the various dark energy models, is well within the error of σ v for most of the parameter spaces of the dark energy models. Thus, a single strong gravitational lensing by use of the Einstein radius may not be a proper method to investigate the property of dark energy. However, better understanding to the mass profile of clusters in the future or other methods related to arc statistics rather than the distances may be used for constraints on dark energy

The Strong Lensing Time Delay Challenge (2014)

Science.gov (United States)

Liao, Kai; Dobler, G.; Fassnacht, C. D.; Treu, T.; Marshall, P. J.; Rumbaugh, N.; Linder, E.; Hojjati, A.

2014-01-01

Time delays between multiple images in strong lensing systems are a powerful probe of cosmology. At the moment the application of this technique is limited by the number of lensed quasars with measured time delays. However, the number of such systems is expected to increase dramatically in the next few years. Hundred such systems are expected within this decade, while the Large Synoptic Survey Telescope (LSST) is expected to deliver of order 1000 time delays in the 2020 decade. In order to exploit this bounty of lenses we needed to make sure the time delay determination algorithms have sufficiently high precision and accuracy. As a first step to test current algorithms and identify potential areas for improvement we have started a "Time Delay Challenge" (TDC). An "evil" team has created realistic simulated light curves, to be analyzed blindly by "good" teams. The challenge is open to all interested parties. The initial challenge consists of two steps (TDC0 and TDC1). TDC0 consists of a small number of datasets to be used as a training template. The non-mandatory deadline is December 1 2013. The "good" teams that complete TDC0 will be given access to TDC1. TDC1 consists of thousands of lightcurves, a number sufficient to test precision and accuracy at the subpercent level, necessary for time-delay cosmography. The deadline for responding to TDC1 is July 1 2014. Submissions will be analyzed and compared in terms of predefined metrics to establish the goodness-of-fit, efficiency, precision and accuracy of current algorithms. This poster describes the challenge in detail and gives instructions for participation.

Dark matter distributions in early-type galaxies from strong gravitational lensing

International Nuclear Information System (INIS)

Eichner, Thomas Martin

2013-01-01

Dark matter constitutes a large fraction of the mass of early-type galaxies. However, the exact amount and spatial distribution of the dark matter, especially in the galaxies' center is still unclear. Furthermore, galaxies in dense environments such as the centers of galaxy clusters shrink in size, since parts of their outer dark matter halo is stripped away. The aim of this thesis is to measure the dark matter content in the centers and outskirts of elliptical galaxies by analyzing the strong gravitational lensing effect they produce. Gravitational lensing is well-suited for investigating dark matter, since it is sensitive to all forms of matter, regardless of its dynamical or evolutionary state. We present gravitational lensing studies of the exceptional strong lensing systems SDSS J1538+5817 and SDSS J1430+4105, identified by the Sloan Lens ACS survey. The lenses are elliptical galaxies at z l =0.143 and z l =0.285, respectively. For SDSS J1538+5817 we show that both multiple imaged sources are located at the same redshift z s =0.531. Its multiple images span a range from 1 to 4 kpc in the plane of the lens. For SDSS J1430+4105, the source at redshift z s =0.575 is imaged into a broad Einstein ring, covering radii from 4 kpc to 10 kpc in the plane of the lens. In both cases, the lensed images can be accurately and consistently reproduced with different modeling approaches. We get projected total masses of 8.11 +0.27 -0.59 x 10 10 M s un within the Einstein radius of 2.5 kpc for SDSS J1538+5817 and 5.37±0.06 x 10 11 M s un within 6.5 kpc for SDSS J1430+4105. The luminous and dark matter were traced separately, resulting in dark matter fractions within the Einstein radius of 0.1 +0.2 -0.1 and 0.40 +0.14 -0.10 for SDSS J1538+5817 and SDSS J1430+4105, respectively. We assume a de Vaucouleurs profile to trace the light distribution of both galaxies. From the stellar mass associated with this light, we can explicitly derive a stellar mass-to-light ratio of (M de

What if LIGO's gravitational wave detections are strongly lensed by massive galaxy clusters?

Science.gov (United States)

Smith, Graham P.; Jauzac, Mathilde; Veitch, John; Farr, Will M.; Massey, Richard; Richard, Johan

2018-04-01

Motivated by the preponderance of so-called `heavy black holes' in the binary black hole (BBH) gravitational wave (GW) detections to date, and the role that gravitational lensing continues to play in discovering new galaxy populations, we explore the possibility that the GWs are strongly lensed by massive galaxy clusters. For example, if one of the GW sources were actually located at z = 1, then the rest-frame mass of the associated BHs would be reduced by a factor of ˜2. Based on the known populations of BBH GW sources and strong-lensing clusters, we estimate a conservative lower limit on the number of BBH mergers detected per detector year at LIGO/Virgo's current sensitivity that are multiply-imaged, of Rdetect ≃ 10-5 yr-1. This is equivalent to rejecting the hypothesis that one of the BBH GWs detected to date was multiply-imaged at ≲4σ. It is therefore unlikely, but not impossible, that one of the GWs is multiply-imaged. We identify three spectroscopically confirmed strong-lensing clusters with well-constrained mass models within the 90 per cent credible sky localizations of the BBH GWs from LIGO's first observing run. In the event that one of these clusters multiply-imaged one of the BBH GWs, we predict that 20-60 per cent of the putative next appearances of the GWs would be detectable by LIGO, and that they would arrive at Earth within 3yr of first detection.

The Impact of Microlensing on the Standardisation of Strongly Lensed Type Ia Supernovae

Science.gov (United States)

Foxley-Marrable, Max; Collett, Thomas E.; Vernardos, Georgios; Goldstein, Daniel A.; Bacon, David

2018-05-01

We investigate the effect of microlensing on the standardisation of strongly lensed Type Ia supernovae (GLSNe Ia). We present predictions for the amount of scatter induced by microlensing across a range of plausible strong lens macromodels. We find that lensed images in regions of low convergence, shear and stellar density are standardisable, where the microlensing scatter is ≲ 0.15 magnitudes, comparable to the intrinsic dispersion of for a typical SN Ia. These standardisable configurations correspond to asymmetric lenses with an image located far outside the Einstein radius of the lens. Symmetric and small Einstein radius lenses (≲ 0.5 arcsec) are not standardisable. We apply our model to the recently discovered GLSN Ia iPTF16geu and find that the large discrepancy between the observed flux and the macromodel predictions from More et al. (2017) cannot be explained by microlensing alone. Using the mock GLSNe Ia catalogue of Goldstein et al. (2017), we predict that ˜ 22% of GLSNe Ia discovered by LSST will be standardisable, with a median Einstein radius of 0.9 arcseconds and a median time-delay of 41 days. By breaking the mass-sheet degeneracy the full LSST GLSNe Ia sample will be able to detect systematics in H0 at the 0.5% level.

RELICS: Strong Lens Models for Five Galaxy Clusters from the Reionization Lensing Cluster Survey

Science.gov (United States)

Cerny, Catherine; Sharon, Keren; Andrade-Santos, Felipe; Avila, Roberto J.; Bradač, Maruša; Bradley, Larry D.; Carrasco, Daniela; Coe, Dan; Czakon, Nicole G.; Dawson, William A.; Frye, Brenda L.; Hoag, Austin; Huang, Kuang-Han; Johnson, Traci L.; Jones, Christine; Lam, Daniel; Lovisari, Lorenzo; Mainali, Ramesh; Oesch, Pascal A.; Ogaz, Sara; Past, Matthew; Paterno-Mahler, Rachel; Peterson, Avery; Riess, Adam G.; Rodney, Steven A.; Ryan, Russell E.; Salmon, Brett; Sendra-Server, Irene; Stark, Daniel P.; Strolger, Louis-Gregory; Trenti, Michele; Umetsu, Keiichi; Vulcani, Benedetta; Zitrin, Adi

2018-06-01

Strong gravitational lensing by galaxy clusters magnifies background galaxies, enhancing our ability to discover statistically significant samples of galaxies at {\\boldsymbol{z}}> 6, in order to constrain the high-redshift galaxy luminosity functions. Here, we present the first five lens models out of the Reionization Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell 2163, RXC J2211.7–0349, and ACT-CLJ0102–49151. The derived lensing magnification is essential for estimating the intrinsic properties of high-redshift galaxy candidates, and properly accounting for the survey volume. We report on new spectroscopic redshifts of multiply imaged lensed galaxies behind these clusters, which are used as constraints, and detail our strategy to reduce systematic uncertainties due to lack of spectroscopic information. In addition, we quantify the uncertainty on the lensing magnification due to statistical and systematic errors related to the lens modeling process, and find that in all but one cluster, the magnification is constrained to better than 20% in at least 80% of the field of view, including statistical and systematic uncertainties. The five clusters presented in this paper span the range of masses and redshifts of the clusters in the RELICS program. We find that they exhibit similar strong lensing efficiencies to the clusters targeted by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the lens models are made available to the community through the Mikulski Archive for Space Telescopes.

EVIDENCE OF VERY LOW METALLICITY AND HIGH IONIZATION STATE IN A STRONGLY LENSED, STAR-FORMING DWARF GALAXY AT z = 3.417

International Nuclear Information System (INIS)

Amorín, R.; Grazian, A.; Castellano, M.; Pentericci, L.; Fontana, A.; Sommariva, V.; Merlin, E.; Van der Wel, A.; Maseda, M.

2014-01-01

We investigate the gas-phase metallicity and Lyman continuum (LyC) escape fraction of a strongly gravitationally lensed, extreme emission-line galaxy at z = 3.417, J1000+0221S, recently discovered by the CANDELS team. We derive ionization- and metallicity-sensitive emission-line ratios from H+K band Large Binocular Telescope (LBT)/LUCI medium resolution spectroscopy. J1000+0221S shows high ionization conditions, as evidenced by its enhanced [O III]/[O II] and [O III]/Hβ ratios. Strong-line methods based on the available line ratios suggest that J1000+0221S is an extremely metal-poor galaxy, with a metallicity of 12+log (O/H) < 7.44 (Z < 0.05 Z ☉ ), placing it among the most metal-poor star-forming galaxies at z ≳ 3 discovered so far. In combination with its low stellar mass (2 × 10 8  M ☉ ) and high star formation rate (5 M ☉  yr –1 ), the metallicity of J1000+0221S is consistent with the extrapolation of the mass-metallicity relation traced by Lyman-break galaxies at z ≳ 3 to low masses, but it is 0.55 dex lower than predicted by the fundamental metallicity relation at z ≲ 2.5. These observations suggest a rapidly growing galaxy, possibly fed by massive accretion of pristine gas. Additionally, deep LBT/LBC photometry in the UGR bands are used to derive a limit to the LyC escape fraction, thus allowing us to explore for the first time the regime of sub-L* galaxies at z > 3. We find a 1σ upper limit to the escape fraction of 23%, which adds a new observational constraint to recent theoretical models predicting that sub-L* galaxies at high-z have high escape fractions and thus are the responsible for the reionization of the universe

OBSERVED SCALING RELATIONS FOR STRONG LENSING CLUSTERS: CONSEQUENCES FOR COSMOLOGY AND CLUSTER ASSEMBLY

International Nuclear Information System (INIS)

Comerford, Julia M.; Moustakas, Leonidas A.; Natarajan, Priyamvada

2010-01-01

Scaling relations of observed galaxy cluster properties are useful tools for constraining cosmological parameters as well as cluster formation histories. One of the key cosmological parameters, σ 8 , is constrained using observed clusters of galaxies, although current estimates of σ 8 from the scaling relations of dynamically relaxed galaxy clusters are limited by the large scatter in the observed cluster mass-temperature (M-T) relation. With a sample of eight strong lensing clusters at 0.3 8 , but combining the cluster concentration-mass relation with the M-T relation enables the inclusion of unrelaxed clusters as well. Thus, the resultant gains in the accuracy of σ 8 measurements from clusters are twofold: the errors on σ 8 are reduced and the cluster sample size is increased. Therefore, the statistics on σ 8 determination from clusters are greatly improved by the inclusion of unrelaxed clusters. Exploring cluster scaling relations further, we find that the correlation between brightest cluster galaxy (BCG) luminosity and cluster mass offers insight into the assembly histories of clusters. We find preliminary evidence for a steeper BCG luminosity-cluster mass relation for strong lensing clusters than the general cluster population, hinting that strong lensing clusters may have had more active merging histories.

STRONG GRAVITATIONAL LENSING BY THE SUPER-MASSIVE cD GALAXY IN ABELL 3827

International Nuclear Information System (INIS)

Carrasco, E. R.; Gomez, P. L.; Lee, H.; Diaz, R.; Bergmann, M.; Turner, J. E. H.; Miller, B. W.; West, M. J.; Verdugo, T.

2010-01-01

We have discovered strong gravitational lensing features in the core of the nearby cluster Abell 3827 by analyzing Gemini South GMOS images. The most prominent strong lensing feature is a highly magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z ∼ 0.2. Located ∼20'' away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z ∼ 0.4. We have modeled the gravitational potential of the cluster core, taking into account the mass from the cluster, the brightest cluster galaxy (BCG), and other galaxies. We derive a total mass of (2.7 ± 0.4) x 10 13 M sun within 37 h -1 kpc. This mass is an order of magnitude larger than that derived from X-ray observations. The total mass derived from lensing data suggests that the BCG in this cluster is perhaps the most massive galaxy in the nearby universe.

The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints

Energy Technology Data Exchange (ETDEWEB)

Newman, Andrew B. [The Observatories of the Carnegie Institution for Science, Pasadena, CA (United States); Smith, Russell J. [Centre for Extragalactic Astronomy, University of Durham, South Road, Durham (United Kingdom); Conroy, Charlie [Department of Astronomy, Harvard University, Cambridge, MA (United States); Villaume, Alexa [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States); Van Dokkum, Pieter, E-mail: anewman@obs.carnegiescience.edu [Department of Astrophysical Sciences, Yale University, New Haven, CT (United States)

2017-08-20

We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar initial mass function (IMF) consistent with that of the Milky Way, not the bottom-heavy IMF that has been reported as typical for high- σ ETGs based on lensing, dynamical, and stellar population synthesis techniques. We use these unique systems to test the consistency of IMF estimates derived from different methods. We first estimate the stellar M {sub *}/ L using lensing and stellar dynamics. We then fit high-quality optical spectra of the lenses using an updated version of the stellar population synthesis models developed by Conroy and van Dokkum. When examined individually, we find good agreement among these methods for one galaxy. The other two galaxies show 2–3 σ tension with lensing estimates, depending on the dark matter contribution, when considering IMFs that extend to 0.08 M {sub ⊙}. Allowing a variable low-mass cutoff or a nonparametric form of the IMF reduces the tension among the IMF estimates to <2 σ . There is moderate evidence for a reduced number of low-mass stars in the SNELLS spectra, but no such evidence in a composite spectrum of matched- σ ETGs drawn from the SDSS. Such variation in the form of the IMF at low stellar masses ( m ≲ 0.3 M {sub ⊙}), if present, could reconcile lensing/dynamical and spectroscopic IMF estimates for the SNELLS lenses and account for their lighter M {sub *}/ L relative to the mean matched- σ ETG. We provide the spectra used in this study to facilitate future comparisons.

Lyman Alpha Control

CERN Document Server

Nielsen, Daniel Stefaniak

2015-01-01

This document gives an overview of how to operate the Lyman Alpha Control application written in LabVIEW along with things to watch out for. Overview of the LabVIEW code itself as well as the physical wiring of and connections from/to the NI PCI-6229 DAQ box is also included. The Lyman Alpha Control application is the interface between the ALPHA sequencer and the HighFinesse Wavelength Meter as well as the Lyman Alpha laser setup. The application measures the wavelength of the output light from the Lyman Alpha cavity through the Wavelength Meter. The application can use the Wavelength Meter’s PID capabilities to stabilize the Lyman Alpha laser output as well as switch between up to three frequencies.

Radio and Gamma-Ray Monitoring of Strongly Lensed Quasars and Blazars

NARCIS (Netherlands)

Rumbaugh, Nick; Fassnacht, Chris; McKean, John; Koopmans, Leon; Auger, Matthew; Suyu, Sherry; Marshall, Philip J.

2015-01-01

We observed six strongly lensed, radio-loud quasars (MG 0414+0534, CLASS B0712+472, JVAS B1030+074, CLASS B1127+385, CLASS B1152+199, and JVAS B1938+666) in order to identify systems suitable for measuring cosmological parameters using time delays between their multiple images. Two separate

Cusp-core problem and strong gravitational lensing

International Nuclear Information System (INIS)

Li Nan; Chen Daming

2009-01-01

Cosmological numerical simulations of galaxy formation have led to the cuspy density profile of a pure cold dark matter halo toward the center, which is in sharp contradiction with the observations of the rotation curves of cold dark matter-dominated dwarf and low surface brightness disk galaxies, with the latter tending to favor mass profiles with a flat central core. Many efforts have been devoted to resolving this cusp-core problem in recent years, among them, baryon-cold dark matter interactions are considered to be the main physical mechanisms erasing the cold dark matter (CDM) cusp into a flat core in the centers of all CDM halos. Clearly, baryon-cold dark matter interactions are not customized only for CDM-dominated disk galaxies, but for all types, including giant ellipticals. We first fit the most recent high resolution observations of rotation curves with the Burkert profile, then use the constrained core size-halo mass relation to calculate the lensing frequency, and compare the predicted results with strong lensing observations. Unfortunately, it turns out that the core size constrained from rotation curves of disk galaxies cannot be extrapolated to giant ellipticals. We conclude that, in the standard cosmological paradigm, baryon-cold dark matter interactions are not universal mechanisms for galaxy formation, and therefore, they cannot be true solutions to the cusp-core problem.

A Robust Mass Estimator for Dark Matter Subhalo Perturbations in Strong Gravitational Lenses

Energy Technology Data Exchange (ETDEWEB)

Minor, Quinn E. [Department of Science, Borough of Manhattan Community College, City University of New York, New York, NY 10007 (United States); Kaplinghat, Manoj [Department of Physics and Astronomy, University of California, Irvine CA 92697 (United States); Li, Nan [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)

2017-08-20

A few dark matter substructures have recently been detected in strong gravitational lenses through their perturbations of highly magnified images. We derive a characteristic scale for lensing perturbations and show that they are significantly larger than the perturber’s Einstein radius. We show that the perturber’s projected mass enclosed within this radius, scaled by the log-slope of the host galaxy’s density profile, can be robustly inferred even if the inferred density profile and tidal radius of the perturber are biased. We demonstrate the validity of our analytic derivation using several gravitational lens simulations where the tidal radii and the inner log-slopes of the density profile of the perturbing subhalo are allowed to vary. By modeling these simulated data, we find that our mass estimator, which we call the effective subhalo lensing mass, is accurate to within about 10% or smaller in each case, whereas the inferred total subhalo mass can potentially be biased by nearly an order of magnitude. We therefore recommend that the effective subhalo lensing mass be reported in future lensing reconstructions, as this will allow for a more accurate comparison with the results of dark matter simulations.

LYMAN : a new window on the universe

International Nuclear Information System (INIS)

Dopita, M.A.; Tuohy, I.R.; Mathewson, D.S.; Hunstead, R.W.; Waterworth, M.D.

1988-01-01

This document is the final Phase A Science Report of the Australian LYMAN Science Working Group, and describes in detail the scientific objectives, technical feasibility, and engineering implementation of the LYMAN mission as developed in the Australian studies. LYMAN represents the next generation, high-orbit, UV space observatory, and is designed to operate over the wavelength range λ 100 - 1900 Angstrom. The prime spectral range is λ 900 - 1250 Angstrom, which will be covered at a resolution of λ/Δ λ = 30000, and the sensitivity of the instrumentation will be orders of magnitude better than previous missions. In this region we find the Lyman series of molecular and atomic hydrogen, as well as a whole host of atomic and ionic lines of great diagnostic power. LYMAN will be able to accomplish uniquely valuable astrophysics as a result, and will be applied to the study of all types of astronomical targets in the fields of cosmology, galactic research, the interstellar medium, stars in all stages of their evolution, and to particular solar system objects. The LYMAN Mission was the subject of a $1M study contract awarded by the Australian Space Office, a section of DITAC, to Auspace Pty. Ltd. The Phase A study was conduced in parallel with the ESA Phase A Study, and with a strong scientific and technical liaison between the two groups. LYMAN is now likely to be launched as a joint ESA/NASA project, but the future Australian role in the mission, as determined by current policy, would be minimal. Australia would therefore be effectively locked out of the very exciting front-line science described in this document, and the valuable university - industry liaison that has been developed over the last eight years will be lost

ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

Energy Technology Data Exchange (ETDEWEB)

Chen, Bin; Maddumage, Prasad [Research Computing Center, Department of Scientific Computing, Florida State University, Tallahassee, FL 32306 (United States); Kantowski, Ronald; Dai, Xinyu; Baron, Eddie, E-mail: bchen3@fsu.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

2015-05-15

Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

International Nuclear Information System (INIS)

Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

2015-01-01

Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python

Serendipitous discovery of a strong-lensed galaxy in integral field spectroscopy from MUSE

Science.gov (United States)

Galbany, Lluís; Collett, Thomas E.; Méndez-Abreu, Jairo; Sánchez, Sebastián F.; Anderson, Joseph P.; Kuncarayakti, Hanindyo

2018-06-01

2MASX J04035024-0239275 is a bright red elliptical galaxy at redshift 0.0661 that presents two extended sources at 2″ to the north-east and 1″ to the south-west. The sizes and surface brightnesses of the two blue sources are consistent with a gravitationally-lensed background galaxy. In this paper we present MUSE observations of this galaxy from the All-weather MUse Supernova Integral-field Nearby Galaxies (AMUSING) survey, and report the discovery of a background lensed galaxy at redshift 0.1915, together with other 15 background galaxies at redshifts ranging from 0.09 to 0.9, that are not multiply imaged. We have extracted aperture spectra of the lens and all the sources and fit the stellar continuum with STARLIGHT to estimate their stellar and emission line properties. A trace of past merger and active nucleus activity is found in the lensing galaxy, while the background lensed galaxy is found to be star-forming. Modeling the lensing potential with a singular isothermal ellipsoid, we find an Einstein radius of 1."45±0."04, which corresponds to 1.9 kpc at the redshift of the lens and it is much smaller than its effective radius (reff ˜ 9″"). Comparing the Einstein mass and the STARLIGHT stellar mass within the same aperture yields a dark matter fraction of 18% ± 8 % within the Einstein radius. The advent of large surveys such as the Large Synoptic Survey Telescope (LSST) will discover a number of strong-lensed systems, and here we demonstrate how wide-field integral field spectroscopy offers an excellent approach to study them and to precisely model lensing effects.

Strongly lensed neutral hydrogen emission: detection predictions with current and future radio interferometers

Science.gov (United States)

Deane, R. P.; Obreschkow, D.; Heywood, I.

2015-09-01

Strong gravitational lensing provides some of the deepest views of the Universe, enabling studies of high-redshift galaxies only possible with next-generation facilities without the lensing phenomenon. To date, 21-cm radio emission from neutral hydrogen has only been detected directly out to z ˜ 0.2, limited by the sensitivity and instantaneous bandwidth of current radio telescopes. We discuss how current and future radio interferometers such as the Square Kilometre Array (SKA) will detect lensed H I emission in individual galaxies at high redshift. Our calculations rely on a semi-analytic galaxy simulation with realistic H I discs (by size, density profile and rotation), in a cosmological context, combined with general relativistic ray tracing. Wide-field, blind H I surveys with the SKA are predicted to be efficient at discovering lensed H I systems, increasingly so at z ≳ 2. This will be enabled by the combination of the magnification boosts, the steepness of the H I luminosity function at the high-mass end, and the fact that the H I spectral line is relatively isolated in frequency. These surveys will simultaneously provide a new technique for foreground lens selection and yield the highest redshift H I emission detections. More near term (and existing) cm-wave facilities will push the high-redshift H I envelope through targeted surveys of known lenses.

Strong deflection lensing by charged black holes in scalar-tensor gravity

Energy Technology Data Exchange (ETDEWEB)

Eiroa, Ernesto F.; Sendra, Carlos M. [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Universidad de Buenos Aires, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

2014-11-15

We examine a class of charged black holes in scalar-tensor gravity as gravitational lenses. We find the deflection angle in the strong deflection limit, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to the Reissner-Norstroem spacetime and we analyze the observational aspects in the case of the Galactic supermassive black hole. (orig.)

A COMPREHENSIVE VIEW OF A STRONGLY LENSED PLANCK-ASSOCIATED SUBMILLIMETER GALAXY

Energy Technology Data Exchange (ETDEWEB)

Fu Hai; Cooray, A. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Jullo, E. [Observatoire d' Astrophysique de Marseille-Provence, 38 rue Frederic Joliot-Curie, F-13388 Marseille (France); Bussmann, R. S. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Ivison, R. J. [UK Astronomy Technology Centre, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom); Perez-Fournon, I. [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain); Djorgovski, S. G.; Scoville, N.; Yan, L.; Riechers, D. A.; Bradford, M. [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Aguirre, J. [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Auld, R. [School of Physics and Astronomy, Cardiff University, The Parade, Cardiff CF24 3AA (United Kingdom); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Baker, A. J. [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, 136 Frelinghuysen Rd., Piscataway, NJ 08854 (United States); Cava, A. [Departamento de Astrofisica, Facultad de CC. Fisicas, Universidad Complutense de Madrid, E-28040 Madrid (Spain); Clements, D. L. [Astrophysics Group, Imperial College London, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom); Dannerbauer, H. [Institut fuer Astronomie, Universitaet Wien, Tuerkenschanzstrasse 17, A-1160 Wien (Austria); Dariush, A. [Physics Department, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); De Zotti, G., E-mail: haif@uci.edu [INAF-Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); and others

2012-07-10

We present high-resolution maps of stars, dust, and molecular gas in a strongly lensed submillimeter galaxy (SMG) at z = 3.259. HATLAS J114637.9-001132 is selected from the Herschel-Astrophysical Terahertz Large Area Survey (H-ATLAS) as a strong lens candidate mainly based on its unusually high 500 {mu}m flux density ({approx}300 mJy). It is the only high-redshift Planck detection in the 130 deg{sup 2} H-ATLAS Phase-I area. Keck Adaptive Optics images reveal a quadruply imaged galaxy in the K band while the Submillimeter Array and the Jansky Very Large Array show doubly imaged 880 {mu}m and CO(1{yields}0) sources, indicating differentiated distributions of the various components in the galaxy. In the source plane, the stars reside in three major kpc-scale clumps extended over {approx}1.6 kpc, the dust in a compact ({approx}1 kpc) region {approx}3 kpc north of the stars, and the cold molecular gas in an extended ({approx}7 kpc) disk {approx}5 kpc northeast of the stars. The emissions from the stars, dust, and gas are magnified by {approx}17, {approx}8, and {approx}7 times, respectively, by four lensing galaxies at z {approx} 1. Intrinsically, the lensed galaxy is a warm (T{sub dust} {approx} 40-65 K), hyper-luminous (L{sub IR} {approx} 1.7 Multiplication-Sign 10{sup 13} L{sub Sun }; star formation rate (SFR) {approx}2000 M{sub Sun} yr{sup -1}), gas-rich (M{sub gas}/M{sub baryon} {approx} 70%), young (M{sub stellar}/SFR {approx} 20 Myr), and short-lived (M{sub gas}/SFR {approx} 40 Myr) starburst. With physical properties similar to unlensed z > 2 SMGs, HATLAS J114637.9-001132 offers a detailed view of a typical SMG through a powerful cosmic microscope.

Probing the Small-scale Structure in Strongly Lensed Systems via Transdimensional Inference

Science.gov (United States)

Daylan, Tansu; Cyr-Racine, Francis-Yan; Diaz Rivero, Ana; Dvorkin, Cora; Finkbeiner, Douglas P.

2018-02-01

Strong lensing is a sensitive probe of the small-scale density fluctuations in the Universe. We implement a pipeline to model strongly lensed systems using probabilistic cataloging, which is a transdimensional, hierarchical, and Bayesian framework to sample from a metamodel (union of models with different dimensionality) consistent with observed photon count maps. Probabilistic cataloging allows one to robustly characterize modeling covariances within and across lens models with different numbers of subhalos. Unlike traditional cataloging of subhalos, it does not require model subhalos to improve the goodness of fit above the detection threshold. Instead, it allows the exploitation of all information contained in the photon count maps—for instance, when constraining the subhalo mass function. We further show that, by not including these small subhalos in the lens model, fixed-dimensional inference methods can significantly mismodel the data. Using a simulated Hubble Space Telescope data set, we show that the subhalo mass function can be probed even when many subhalos in the sample catalogs are individually below the detection threshold and would be absent in a traditional catalog. The implemented software, Probabilistic Cataloger (PCAT) is made publicly available at https://github.com/tdaylan/pcat.

SPITZER ULTRA FAINT SURVEY PROGRAM (SURFS UP). II. IRAC-DETECTED LYMAN-BREAK GALAXIES AT 6 ≲ z ≲ 10 BEHIND STRONG-LENSING CLUSTERS

Energy Technology Data Exchange (ETDEWEB)

Huang, Kuang-Han; Bradač, Maruša; Hoag, Austin; Cain, Benjamin; Lubin, L. M.; Knight, Robert I. [University of California Davis, 1 Shields Avenue, Davis, CA 95616 (United States); Lemaux, Brian C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Ryan, R. E. Jr.; Brammer, Gabriel B. [Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France); Castellano, Marco; Amorin, Ricardo; Fontana, Adriano; Merlin, Emiliano [INAF—Osservatorio Astronomico di Roma Via Frascati 33, I-00040 Monte Porzio Catone (Italy); Schmidt, Kasper B. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Schrabback, Tim [Argelander-Institut für Astronomie, Auf Dem Hügel 71, D-53121 Bonn (Germany); Treu, Tommaso [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095 (United States); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Linden, Anja von der, E-mail: khhuang@ucdavis.edu, E-mail: astrokuang@gmail.com [Department of Physics, Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305 (United States)

2016-01-20

We study the stellar population properties of the IRAC-detected 6 ≲ z ≲ 10 galaxy candidates from the Spitzer UltRa Faint SUrvey Program. Using the Lyman Break selection technique, we find a total of 17 galaxy candidates at 6 ≲ z ≲ 10 from Hubble Space Telescope images (including the full-depth images from the Hubble Frontier Fields program for MACS 1149 and MACS 0717) that have detections at signal-to-noise ratios  ≥ 3 in at least one of the IRAC 3.6 and 4.5 μm channels. According to the best mass models available for the surveyed galaxy clusters, these IRAC-detected galaxy candidates are magnified by factors of ∼1.2–5.5. Due to the magnification of the foreground galaxy clusters, the rest-frame UV absolute magnitudes M{sub 1600} are between −21.2 and −18.9 mag, while their intrinsic stellar masses are between 2 × 10{sup 8}M{sub ⊙} and 2.9 × 10{sup 9}M{sub ⊙}. We identify two Lyα emitters in our sample from the Keck DEIMOS spectra, one at z{sub Lyα} = 6.76 (in RXJ 1347) and one at z{sub Lyα} = 6.32 (in MACS 0454). We find that 4 out of 17 z ≳ 6 galaxy candidates are favored by z ≲ 1 solutions when IRAC fluxes are included in photometric redshift fitting. We also show that IRAC [3.6]–[4.5] color, when combined with photometric redshift, can be used to identify galaxies which likely have strong nebular emission lines or obscured active galactic nucleus contributions within certain redshift windows.

Reducing biases on H0 measurements using strong lensing and galaxy dynamics: results from the EAGLE simulation

Science.gov (United States)

Tagore, Amitpal S.; Barnes, David J.; Jackson, Neal; Kay, Scott T.; Schaller, Matthieu; Schaye, Joop; Theuns, Tom

2018-03-01

Cosmological parameter constraints from observations of time-delay lenses are becoming increasingly precise. However, there may be significant bias and scatter in these measurements due to, among other things, the so-called mass-sheet degeneracy. To estimate these uncertainties, we analyse strong lenses from the largest EAGLE hydrodynamical simulation. We apply a mass-sheet transformation to the radial density profiles of lenses, and by selecting lenses near isothermality, we find that the bias on H0 can be reduced to 5 per cent with an intrinsic scatter of 10 per cent, confirming previous results performed on a different simulation data set. We further investigate whether combining lensing observables with kinematic constraints helps to minimize this bias. We do not detect any significant dependence of the bias on lens model parameters or observational properties of the galaxy, but depending on the source-lens configuration, a bias may still exist. Cross lenses provide an accurate estimate of the Hubble constant, while fold (double) lenses tend to be biased low (high). With kinematic constraints, double lenses show bias and intrinsic scatter of 6 per cent and 10 per cent, respectively, while quad lenses show bias and intrinsic scatter of 0.5 per cent and 10 per cent, respectively. For lenses with a reduced χ2 > 1, a power-law dependence of the χ2 on the lens environment (number of nearby galaxies) is seen. Lastly, we model, in greater detail, the cases of two double lenses that are significantly biased. We are able to remove the bias, suggesting that the remaining biases could also be reduced by carefully taking into account additional sources of systematic uncertainty.

Strong lensing of a regular black hole with an electrodynamics source

Science.gov (United States)

Manna, Tuhina; Rahaman, Farook; Molla, Sabiruddin; Bhadra, Jhumpa; Shah, Hasrat Hussain

2018-05-01

In this paper we have investigated the gravitational lensing phenomenon in the strong field regime for a regular, charged, static black holes with non-linear electrodynamics source. We have obtained the angle of deflection and compared it to a Schwarzschild black hole and Reissner Nordström black hole with similar properties. We have also done a graphical study of the relativistic image positions and magnifications. We hope that this method may be useful in the detection of non-luminous bodies like this current black hole.

Strong lensing probability in TeVeS (tensor-vector-scalar) theory

Science.gov (United States)

Chen, Da-Ming

2008-01-01

We recalculate the strong lensing probability as a function of the image separation in TeVeS (tensor-vector-scalar) cosmology, which is a relativistic version of MOND (MOdified Newtonian Dynamics). The lens is modeled by the Hernquist profile. We assume an open cosmology with Ωb = 0.04 and ΩΛ = 0.5 and three different kinds of interpolating functions. Two different galaxy stellar mass functions (GSMF) are adopted: PHJ (Panter, Heavens and Jimenez 2004 Mon. Not. R. Astron. Soc. 355 764) determined from SDSS data release 1 and Fontana (Fontana et al 2006 Astron. Astrophys. 459 745) from GOODS-MUSIC catalog. We compare our results with both the predicted probabilities for lenses from singular isothermal sphere galaxy halos in LCDM (Lambda cold dark matter) with a Schechter-fit velocity function, and the observational results for the well defined combined sample of the Cosmic Lens All-Sky Survey (CLASS) and Jodrell Bank/Very Large Array Astrometric Survey (JVAS). It turns out that the interpolating function μ(x) = x/(1+x) combined with Fontana GSMF matches the results from CLASS/JVAS quite well.

THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT

International Nuclear Information System (INIS)

Hayes, Matthew; Östlin, Göran; Duval, Florent; Guaita, Lucia; Melinder, Jens; Sandberg, Andreas; Schaerer, Daniel; Verhamme, Anne; Orlitová, Ivana; Mas-Hesse, J. Miguel; Otí-Floranes, Héctor; Adamo, Angela; Atek, Hakim; Cannon, John M.; Herenz, E. Christian; Kunth, Daniel; Laursen, Peter

2013-01-01

We report on new imaging observations of the Lyman alpha emission line (Lyα), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 P20 , Lyα radii are larger than those of Hα by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Lyα-to-FUV radii is 2.9. This suggests that much of the Lyα light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Lyα compared to Hα, ξ Lyα = R Lyα P20 /R Hα P20 , we find ξ Lyα to be uncorrelated with total Lyα luminosity. However, ξ Lyα is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Lyα photons throughout the interstellar medium and drive a large extended Lyα halo.

Null Geodesics and Strong Field Gravitational Lensing in a String Cloud Background

International Nuclear Information System (INIS)

Iftikhar, Sehrish; Sharif, M.

2015-01-01

This paper is devoted to studying two interesting issues of a black hole with string cloud background. Firstly, we investigate null geodesics and find unstable orbital motion of particles. Secondly, we calculate deflection angle in strong field limit. We then find positions, magnifications, and observables of relativistic images for supermassive black hole at the galactic center. We conclude that string parameter highly affects the lensing process and results turn out to be quite different from the Schwarzschild black hole

Strong lensing probability in TeVeS (tensor–vector–scalar) theory

International Nuclear Information System (INIS)

Chen Daming

2008-01-01

We recalculate the strong lensing probability as a function of the image separation in TeVeS (tensor–vector–scalar) cosmology, which is a relativistic version of MOND (MOdified Newtonian Dynamics). The lens is modeled by the Hernquist profile. We assume an open cosmology with Ω b = 0.04 and Ω Λ = 0.5 and three different kinds of interpolating functions. Two different galaxy stellar mass functions (GSMF) are adopted: PHJ (Panter, Heavens and Jimenez 2004 Mon. Not. R. Astron. Soc. 355 764) determined from SDSS data release 1 and Fontana (Fontana et al 2006 Astron. Astrophys. 459 745) from GOODS-MUSIC catalog. We compare our results with both the predicted probabilities for lenses from singular isothermal sphere galaxy halos in LCDM (Lambda cold dark matter) with a Schechter-fit velocity function, and the observational results for the well defined combined sample of the Cosmic Lens All-Sky Survey (CLASS) and Jodrell Bank/Very Large Array Astrometric Survey (JVAS). It turns out that the interpolating function μ(x) = x/(1+x) combined with Fontana GSMF matches the results from CLASS/JVAS quite well

OBSERVATION AND CONFIRMATION OF SIX STRONG-LENSING SYSTEMS IN THE DARK ENERGY SURVEY SCIENCE VERIFICATION DATA

International Nuclear Information System (INIS)

Nord, B.; Buckley-Geer, E.; Lin, H.; Diehl, H. T.; Kuropatkin, N.; Allam, S.; Finley, D. A.; Flaugher, B.; Gaitsch, H.; Merritt, K. W.; Helsby, J.; Amara, A.; Collett, T.; Caminha, G. B.; De Bom, C.; Da Pereira, M. Elidaiana S.; Desai, S.; Dúmet-Montoya, H.; Furlanetto, C.; Gill, M.

2016-01-01

We report the observation and confirmation of the first group- and cluster-scale strong gravitational lensing systems found in Dark Energy Survey data. Through visual inspection of data from the Science Verification season, we identified 53 candidate systems. We then obtained spectroscopic follow-up of 21 candidates using the Gemini Multi-object Spectrograph at the Gemini South telescope and the Inamori-Magellan Areal Camera and Spectrograph at the Magellan/Baade telescope. With this follow-up, we confirmed six candidates as gravitational lenses: three of the systems are newly discovered, and the remaining three were previously known. Of the 21 observed candidates, the remaining 15 either were not detected in spectroscopic observations, were observed and did not exhibit continuum emission (or spectral features), or were ruled out as lensing systems. The confirmed sample consists of one group-scale and five galaxy-cluster-scale lenses. The lensed sources range in redshift z ∼ 0.80–3.2 and in i -band surface brightness i SB ∼ 23–25 mag arcsec −2 (2″ aperture). For each of the six systems, we estimate the Einstein radius θ E and the enclosed mass M enc , which have ranges θ E ∼ 5″–9″ and M enc ∼ 8 × 10 12 to 6 × 10 13 M ⊙ , respectively.

OBSERVATION AND CONFIRMATION OF SIX STRONG-LENSING SYSTEMS IN THE DARK ENERGY SURVEY SCIENCE VERIFICATION DATA

Energy Technology Data Exchange (ETDEWEB)

Nord, B.; Buckley-Geer, E.; Lin, H.; Diehl, H. T.; Kuropatkin, N.; Allam, S.; Finley, D. A.; Flaugher, B.; Gaitsch, H.; Merritt, K. W. [Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Helsby, J. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Amara, A. [Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 16, CH-8093 Zurich (Switzerland); Collett, T. [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Caminha, G. B.; De Bom, C.; Da Pereira, M. Elidaiana S. [ICRA, Centro Brasileiro de Pesquisas Físicas, Rua Dr. Xavier Sigaud 150, CEP 22290-180, Rio de Janeiro, RJ (Brazil); Desai, S. [Excellence Cluster Universe, Boltzmannstrasse 2, D-85748 Garching (Germany); Dúmet-Montoya, H. [Universidade Federal do Rio de Janeiro—Campus Macaé, Rua Aloísio Gomes da Silva, 50—Granja dos Cavaleiros, Cep: 27930-560, Macaé, RJ (Brazil); Furlanetto, C. [University of Nottingham, School of Physics and Astronomy, Nottingham NG7 2RD (United Kingdom); Gill, M., E-mail: nord@fnal.gov [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Collaboration: DES Collaboration; and others

2016-08-10

We report the observation and confirmation of the first group- and cluster-scale strong gravitational lensing systems found in Dark Energy Survey data. Through visual inspection of data from the Science Verification season, we identified 53 candidate systems. We then obtained spectroscopic follow-up of 21 candidates using the Gemini Multi-object Spectrograph at the Gemini South telescope and the Inamori-Magellan Areal Camera and Spectrograph at the Magellan/Baade telescope. With this follow-up, we confirmed six candidates as gravitational lenses: three of the systems are newly discovered, and the remaining three were previously known. Of the 21 observed candidates, the remaining 15 either were not detected in spectroscopic observations, were observed and did not exhibit continuum emission (or spectral features), or were ruled out as lensing systems. The confirmed sample consists of one group-scale and five galaxy-cluster-scale lenses. The lensed sources range in redshift z ∼ 0.80–3.2 and in i -band surface brightness i {sub SB} ∼ 23–25 mag arcsec{sup −2} (2″ aperture). For each of the six systems, we estimate the Einstein radius θ {sub E} and the enclosed mass M {sub enc}, which have ranges θ {sub E} ∼ 5″–9″ and M {sub enc} ∼ 8 × 10{sup 12} to 6 × 10{sup 13} M {sub ⊙}, respectively.

Cosmological Studies with Galaxy Clusters, Active Galactic Nuclei, and Strongly Lensed Quasars

Science.gov (United States)

Rumbaugh, Nicholas Andrew

transitional `green valley' on a color-magnitude diagram. Spectral analysis of the AGN hosts showed that the average host galaxy had either on-going or recent star formation, and was younger than the average galaxy, across all LSS in our sample. We further subdivided our sample in two based on the average evolutionary state of the LSS. The AGN in the more evolved structures had lower X-ray luminosities and longer times since last starburst. These results provide some evidence for merger-based AGN triggering, although other mechanisms, and possibly more than one, could be responsible. In the third study, we probed LambdaCDM cosmology from a different angle. An important part of the model is the cosmological parameters that define our universe. As such, probes that can more accurately and precisely measure these parameters, such as H0 and the dark energy equation of state, w, can allow us to more closely inspect the model. Strongly-lensed quasars provide one such probe, and we sought to perform the first step in using them for cosmological inference, which is to measure the time delays between strongly lensed images. We performed radio monitoring campaigns on six strongly lensed quasars using the Very Large Array. Lightcurves were extracted for each lensed image and analyzed for intrinsic variability. Two lensed quasars showed strong time variations, but the variations were linear in time, preventing precise time delay measurements due to a degeneracy with the magnifications. These results suggest most of the systems should be targeted for followup monitoring, and we estimate that time delays can be measured for the most variable systems with precision of 0.5 to 3.5 days with two more seasons of monitoring. In a joint fit with previously studied systems, these measurements could tighten constraints on H 0 by up to ~1.4.

Core or Cusps: The Central Dark Matter Profile of a Strong Lensing Cluster with a Bright Central Image at Redshift 1

Energy Technology Data Exchange (ETDEWEB)

Collett, Thomas E.; Buckley-Geer, Elizabeth; Lin, Huan; Bacon, David; Nichol, Robert C.; Nord, Brian; Morice-Atkinson, Xan; Amara, Adam; Birrer, Simon; Kuropatkin, Nikolay; More, Anupreeta; Papovich, Casey; Romer, Kathy K.; Tessore, Nicolas; Abbott, Tim M. C.; Allam, Sahar; Annis, James; Benoit-Lévy, Aurlien; Brooks, David; Burke, David L.; Carrasco Kind, Matias; Castander, Francisco Javier J.; D’Andrea, Chris B.; da Costa, Luiz N.; Desai, Shantanu; Diehl, H. Thomas; Doel, Peter; Eifler, Tim F.; Flaugher, Brenna; Frieman, Josh; Gerdes, David W.; Goldstein, Daniel A.; Gruen, Daniel; Gschwend, Julia; Gutierrez, Gaston; James, David J.; Kuehn, Kyler; Kuhlmann, Steve; Lahav, Ofer; Li, Ting S.; Lima, Marcos; Maia, Marcio A. G.; March, Marisa; Marshall, Jennifer L.; Martini, Paul; Melchior, Peter; Miquel, Ramon; Plazas, Andrs A.; Rykoff, Eli S.; Sanchez, Eusebio; Scarpine, Vic; Schindler, Rafe; Schubnell, Michael; Sevilla-Noarbe, Ignacio; Smith, Mathew; Sobreira, Flavia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Tucker, Douglas L.; Walker, Alistair R.

2017-07-10

We report on SPT-CLJ2011-5228, a giant system of arcs created by a cluster at $z=1.06$. The arc system is notable for the presence of a bright central image. The source is a Lyman Break galaxy at $z_s=2.39$ and the mass enclosed within the 14 arc second radius Einstein ring is $10^{14.2}$ solar masses. We perform a full light profile reconstruction of the lensed images to precisely infer the parameters of the mass distribution. The brightness of the central image demands that the central total density profile of the lens be shallow. By fitting the dark matter as a generalized Navarro-Frenk-White profile---with a free parameter for the inner density slope---we find that the break radius is $270^{+48}_{-76}$ kpc, and that the inner density falls with radius to the power $-0.38\\pm0.04$ at 68 percent confidence. Such a shallow profile is in strong tension with our understanding of relaxed cold dark matter halos; dark matter only simulations predict the inner density should fall as $r^{-1}$. The tension can be alleviated if this cluster is in fact a merger; a two halo model can also reconstruct the data, with both clumps (density going as $r^{-0.8}$ and $r^{-1.0}$) much more consistent with predictions from dark matter only simulations. At the resolution of our Dark Energy Survey imaging, we are unable to choose between these two models, but we make predictions for forthcoming Hubble Space Telescope imaging that will decisively distinguish between them.

The Lyman alpha reference sample

DEFF Research Database (Denmark)

Hayes, M.; Östlin, G.; Schaerer, D.

2013-01-01

We report on new imaging observations of the Lyman alpha emission line (Lyα), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028

Probing Motion of Fast Radio Burst Sources by Timing Strongly Lensed Repeaters

Science.gov (United States)

Dai, Liang; Lu, Wenbin

2017-09-01

Given the possible repetitive nature of fast radio bursts (FRBs), their cosmological origin, and their high occurrence, detection of strongly lensed sources due to intervening galaxy lenses is possible with forthcoming radio surveys. We show that if multiple images of a repeating source are resolved with VLBI, using a method independent of lens modeling, accurate timing could reveal non-uniform motion, either physical or apparent, of the emission spot. This can probe the physical nature of FRBs and their surrounding environments, constraining scenarios including orbital motion around a stellar companion if FRBs require a compact star in a special system, and jet-medium interactions for which the location of the emission spot may randomly vary. The high timing precision possible for FRBs (˜ms) compared with the typical time delays between images in galaxy lensing (≳10 days) enables the measurement of tiny fractional changes in the delays (˜ {10}-9) and hence the detection of time-delay variations induced by relative motions between the source, the lens, and the Earth. We show that uniform cosmic peculiar velocities only cause the delay time to drift linearly, and that the effect from the Earth’s orbital motion can be accurately subtracted, thus enabling a search for non-trivial source motion. For a timing accuracy of ˜1 ms and a repetition rate (of detected bursts) of ˜0.05 per day of a single FRB source, non-uniform displacement ≳0.1-1 au of the emission spot perpendicular to the line of sight is detectable if repetitions are seen over a period of hundreds of days.

SDSS-IV MaNGA: the spectroscopic discovery of strongly lensed galaxies

Science.gov (United States)

Talbot, Michael S.; Brownstein, Joel R.; Bolton, Adam S.; Bundy, Kevin; Andrews, Brett H.; Cherinka, Brian; Collett, Thomas E.; More, Anupreeta; More, Surhud; Sonnenfeld, Alessandro; Vegetti, Simona; Wake, David A.; Weijmans, Anne-Marie; Westfall, Kyle B.

2018-06-01

We present a catalogue of 38 spectroscopically detected strong galaxy-galaxy gravitational lens candidates identified in the Sloan Digital Sky Survey IV (SDSS-IV). We were able to simulate narrow-band images for eight of them demonstrating evidence of multiple images. Two of our systems are compound lens candidates, each with two background source-planes. One of these compound systems shows clear lensing features in the narrow-band image. Our sample is based on 2812 galaxies observed by the Mapping Nearby Galaxies at APO (MaNGA) integral field unit (IFU). This Spectroscopic Identification of Lensing Objects (SILO) survey extends the methodology of the Sloan Lens ACS Survey (SLACS) and BOSS Emission-Line Survey (BELLS) to lower redshift and multiple IFU spectra. We searched ˜1.5 million spectra, of which 3065 contained multiple high signal-to-noise ratio background emission-lines or a resolved [O II] doublet, that are included in this catalogue. Upon manual inspection, we discovered regions with multiple spectra containing background emission-lines at the same redshift, providing evidence of a common source-plane geometry which was not possible in previous SLACS and BELLS discovery programs. We estimate more than half of our candidates have an Einstein radius ≳ 1.7 arcsec, which is significantly greater than seen in SLACS and BELLS. These larger Einstein radii produce more extended images of the background galaxy increasing the probability that a background emission-line will enter one of the IFU spectroscopic fibres, making detection more likely.

Power spectrum of dark matter substructure in strong gravitational lenses

Science.gov (United States)

Diaz Rivero, Ana; Cyr-Racine, Francis-Yan; Dvorkin, Cora

2018-01-01

Studying the smallest self-bound dark matter structure in our Universe can yield important clues about the fundamental particle nature of dark matter. Galaxy-scale strong gravitational lensing provides a unique way to detect and characterize dark matter substructures at cosmological distances from the Milky Way. Within the cold dark matter (CDM) paradigm, the number of low-mass subhalos within lens galaxies is expected to be large, implying that their contribution to the lensing convergence field is approximately Gaussian and could thus be described by their power spectrum. We develop here a general formalism to compute from first principles the substructure convergence power spectrum for different populations of dark matter subhalos. As an example, we apply our framework to two distinct subhalo populations: a truncated Navarro-Frenk-White subhalo population motivated by standard CDM, and a truncated cored subhalo population motivated by self-interacting dark matter (SIDM). We study in detail how the subhalo abundance, mass function, internal density profile, and concentration affect the amplitude and shape of the substructure power spectrum. We determine that the power spectrum is mostly sensitive to a specific combination of the subhalo abundance and moments of the mass function, as well as to the average tidal truncation scale of the largest subhalos included in the analysis. Interestingly, we show that the asymptotic slope of the substructure power spectrum at large wave number reflects the internal density profile of the subhalos. In particular, the SIDM power spectrum exhibits a characteristic steepening at large wave number absent in the CDM power spectrum, opening the possibility of using this observable, if at all measurable, to discern between these two scenarios.

The SPT+Herschel+ALMA+Spitzer Legacy Survey: The stellar content of high redshift strongly lensed systems

Science.gov (United States)

Vieira, Joaquin; Ashby, Matt; Carlstrom, John; Chapman, Scott; DeBreuck, Carlos; Fassnacht, Chris; Gonzalez, Anthony; Phadke, Kedar; Marrone, Dan; Malkan, Matt; Reuter, Cassie; Rotermund, Kaja; Spilker, Justin; Weiss, Axel

2018-05-01

The South Pole Telescope (SPT) has systematically identified 90 high-redshift strongly gravitationally lensed submillimeter galaxies (SMGs) in a 2500 square-degree cosmological survey of the millimeter (mm) sky. These sources are selected by their extreme mm flux, which is largely independent of redshift and lensing configuration. We are undertaking a comprehensive and systematic followup campaign to use these "cosmic magnifying glasses" to study the infrared background in unprecedented detail, inform the condition of the interstellar medium in starburst galaxies at high redshift, and place limits on dark matter substructure. Here we ask for 115.4 hours of deep Spitzer/IRAC imaging to complete our survey of 90 systems to a uniform depth of 30min integrations at 3.6um and 60min at 4.5um. In our sample of 90 systems, 16 have already been fully observed, 30 have been partially observed, and 44 have not been observed at all. Our immediate goals are to: 1) constrain the specific star formation rates of the background high-redshift submillimeter galaxies by combining these Spitzer observations with our APEX, Herschel, and ALMA data, 2) robustly determine the stellar masses and mass-to-light ratios of all the foreground lensing galaxies in the sample by combining these observations with our VLT and Gemini data, the Dark Energy Survey, and ALMA; and 3) provide complete, deep, and uniform NIR coverage of our entire sample of lensed systems to characterize the environments of high redshift SMGs, maximize the discovery potential for additional spectacular and rare sources, and prepare for JWST. This program will provide the cornerstone data set for two PhD theses: Kedar Phadke at Illinois will lead the analysis of stellar masses for the background SMGs, and Kaja Rotermund at Dalhousie will lead the analysis of stellar masses for the foreground lenses.

The effect of stellar evolution uncertainties on the rest-frame ultraviolet stellar lines of C IV and He II in high-redshift Lyman-break galaxies

Science.gov (United States)

Eldridge, John J.; Stanway, Elizabeth R.

2012-01-01

Young, massive stars dominate the rest-frame ultraviolet (UV) spectra of star-forming galaxies. At high redshifts (z > 2), these rest-frame UV features are shifted into the observed-frame optical and a combination of gravitational lensing, deep spectroscopy and spectral stacking analysis allows the stellar population characteristics of these sources to be investigated. We use our stellar population synthesis code Binary Population and Spectral Synthesis (BPASS) to fit two strong rest-frame UV spectral features in published Lyman-break galaxy spectra, taking into account the effects of binary evolution on the stellar spectrum. In particular, we consider the effects of quasi-homogeneous evolution (arising from the rotational mixing of rapidly rotating stars), metallicity and the relative abundance of carbon and oxygen on the observed strengths of He IIλ1640 Å and C IVλ1548, 1551 Å spectral lines. We find that Lyman-break galaxy spectra at z ˜ 2-3 are best fitted with moderately sub-solar metallicities, and with a depleted carbon-to-oxygen ratio. We also find that the spectra of the lowest metallicity sources are best fitted with model spectra in which the He II emission line is boosted by the inclusion of the effect of massive stars being spun-up during binary mass transfer so these rapidly rotating stars experience quasi-homogeneous evolution.

The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%

Energy Technology Data Exchange (ETDEWEB)

Rutkowski, Michael J.; Hayes, Matthew [Department of Astronomy, AlbaNova University Centre, Stockholm University, SE-10691 Stockholm (Sweden); Scarlata, Claudia; Mehta, Vihang [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Henry, Alaina; Hathi, Nimish; Koekemoer, Anton M. [Space Telescope Science Institute, Baltimore, MD 21218 (United States); Cohen, Seth; Windhorst, Rogier [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85281 (United States); Teplitz, Harry I. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Haardt, Francesco [DiSAT, Università dellInsubria, via Valleggio 11, I-22100 Como (Italy); Siana, Brian [Department of Physics, University of California, Riverside, CA 92521 (United States)

2017-06-01

Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission ( N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1 σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f {sub esc} ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f {sub esc} ≲ 14.0%. Our observations are not deep enough to detect f {sub esc} ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

The Lyman Continuum Escape Fraction of Emission Line-selected z ∼ 2.5 Galaxies Is Less Than 15%

International Nuclear Information System (INIS)

Rutkowski, Michael J.; Hayes, Matthew; Scarlata, Claudia; Mehta, Vihang; Henry, Alaina; Hathi, Nimish; Koekemoer, Anton M.; Cohen, Seth; Windhorst, Rogier; Teplitz, Harry I.; Haardt, Francesco; Siana, Brian

2017-01-01

Recent work suggests that strong emission line, star-forming galaxies (SFGs) may be significant Lyman continuum leakers. We combine archival Hubble Space Telescope broadband ultraviolet and optical imaging (F275W and F606W, respectively) with emission line catalogs derived from WFC3 IR G141 grism spectroscopy to search for escaping Lyman continuum (LyC) emission from homogeneously selected z ∼ 2.5 SFGs. We detect no escaping Lyman continuum from SFGs selected on [O ii] nebular emission ( N = 208) and, within a narrow redshift range, on [O iii]/[O ii]. We measure 1 σ upper limits to the LyC escape fraction relative to the non-ionizing UV continuum from [O ii] emitters, f _e_s_c ≲ 5.6%, and strong [O iii]/[O ii] > 5 ELGs, f _e_s_c ≲ 14.0%. Our observations are not deep enough to detect f _e_s_c ∼ 10% typical of low-redshift Lyman continuum emitters. However, we find that this population represents a small fraction of the star-forming galaxy population at z ∼ 2. Thus, unless the number of extreme emission line galaxies grows substantially to z ≳ 6, such galaxies may be insufficient for reionization. Deeper survey data in the rest-frame ionizing UV will be necessary to determine whether strong line ratios could be useful for pre-selecting LyC leakers at high redshift.

Weak lensing and CMB: Parameter forecasts including a running spectral index

International Nuclear Information System (INIS)

Ishak, Mustapha; Hirata, Christopher M.; McDonald, Patrick; Seljak, Uros

2004-01-01

We use statistical inference theory to explore the constraints from future galaxy weak lensing (cosmic shear) surveys combined with the current CMB constraints on cosmological parameters, focusing particularly on the running of the spectral index of the primordial scalar power spectrum, α s . Recent papers have drawn attention to the possibility of measuring α s by combining the CMB with galaxy clustering and/or the Lyman-α forest. Weak lensing combined with the CMB provides an alternative probe of the primordial power spectrum. We run a series of simulations with variable runnings and compare them to semianalytic nonlinear mappings to test their validity for our calculations. We find that a 'reference' cosmic shear survey with f sky =0.01 and 6.6x10 8 galaxies per steradian can reduce the uncertainty on n s and α s by roughly a factor of 2 relative to the CMB alone. We investigate the effect of shear calibration biases on lensing by including the calibration factor as a parameter, and show that for our reference survey, the precision of cosmological parameter determination is only slightly degraded even if the amplitude calibration is uncertain by as much as 5%. We conclude that in the near future weak lensing surveys can supplement the CMB observations to constrain the primordial power spectrum

Interpreting the Strongly Lensed Supernova iPTF16geu: Time Delay Predictions, Microlensing, and Lensing Rates

Energy Technology Data Exchange (ETDEWEB)

More, Anupreeta; Oguri, Masamune; More, Surhud [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Chiba 277-8583 (Japan); Suyu, Sherry H. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Lee, Chien-Hsiu, E-mail: anupreeta.more@ipmu.jp [Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720 (United States)

2017-02-01

We present predictions for time delays between multiple images of the gravitationally lensed supernova, iPTF16geu, which was recently discovered from the intermediate Palomar Transient Factory (iPTF). As the supernova is of Type Ia where the intrinsic luminosity is usually well known, accurately measured time delays of the multiple images could provide tight constraints on the Hubble constant. According to our lens mass models constrained by the Hubble Space Telescope F814W image, we expect the maximum relative time delay to be less than a day, which is consistent with the maximum of 100 hr reported by Goobar et al. but places a stringent upper limit. Furthermore, the fluxes of most of the supernova images depart from expected values suggesting that they are affected by microlensing. The microlensing timescales are small enough that they may pose significant problems to measure the time delays reliably. Our lensing rate calculation indicates that the occurrence of a lensed SN in iPTF is likely. However, the observed total magnification of iPTF16geu is larger than expected, given its redshift. This may be a further indication of ongoing microlensing in this system.

SPITZER IMAGING OF STRONGLY LENSED HERSCHEL-SELECTED DUSTY STAR-FORMING GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Ma, Brian; Cooray, Asantha; Calanog, J. A.; Nayyeri, H.; Timmons, N.; Casey, C. [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Baes, M. [Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281 S9, B-9000 Gent (Belgium); Chapman, S. [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2 (Canada); Dannerbauer, H. [Laboratoire AIM-Paris-Saclay, CEA/DSM/Irfu-CNRS-Université Paris Diderot, CE-Saclay, pt courrier 131, F-91191 Gif-sur-Yvette (France); Da Cunha, E. [Center for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn VIC 3122 (Australia); De Zotti, G. [INAF-Osservatorio Astronomico di Padova, Vicolo Osservatorio 5, I-35122 Padova (Italy); Dunne, L.; Michałowski, M. J.; Oteo, I. [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fu, Hai [Department of Physics and Astronomy, University of Iowa, Van Allen Hall, Iowa City, IA 52242 (United States); Gonzalez-Nuevo, J. [Departamento de Fisica, Universidad de Oviedo C/ Calvo Sotelo, s/n, E-33007 Oviedo (Spain); Magdis, G. [Department of Astrophysics, Denys Wilkinson Building, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Riechers, D. A. [Department of Astronomy, Cornell University, 220 Space Sciences Building, Ithaca, NY 14853 (United States); Scott, D. [Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); and others

2015-11-20

We present the rest-frame optical spectral energy distribution (SED) and stellar masses of six Herschel-selected gravitationally lensed dusty, star-forming galaxies (DSFGs) at 1 < z < 3. These galaxies were first identified with Herschel/SPIRE imaging data from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) and the Herschel Multi-tiered Extragalactic Survey (HerMES). The targets were observed with Spitzer/IRAC at 3.6 and 4.5 μm. Due to the spatial resolution of the IRAC observations at the level of 2″, the lensing features of a background DSFG in the near-infrared are blended with the flux from the foreground lensing galaxy in the IRAC imaging data. We make use of higher resolution Hubble/WFC3 or Keck/NIRC2 Adaptive Optics imaging data to fit light profiles of the foreground lensing galaxy (or galaxies) as a way to model the foreground components, in order to successfully disentangle the foreground lens and background source flux densities in the IRAC images. The flux density measurements at 3.6 and 4.5 μm, once combined with Hubble/WFC3 and Keck/NIRC2 data, provide important constraints on the rest-frame optical SED of the Herschel-selected lensed DSFGs. We model the combined UV- to millimeter-wavelength SEDs to establish the stellar mass, dust mass, star formation rate, visual extinction, and other parameters for each of these Herschel-selected DSFGs. These systems have inferred stellar masses in the range 8 × 10{sup 10}–4 × 10{sup 11} M{sub ⊙} and star formation rates of around 100 M{sub ⊙} yr{sup −1}. This puts these lensed submillimeter systems well above the SFR-M* relation observed for normal star-forming galaxies at similar redshifts. The high values of SFR inferred for these systems are consistent with a major merger-driven scenario for star formation.

Variability of the Lyman alpha flux with solar activity

International Nuclear Information System (INIS)

Lean, J.L.; Skumanich, A.

1983-01-01

A three-component model of the solar chromosphere, developed from ground based observations of the Ca II K chromospheric emission, is used to calculate the variability of the Lyman alpha flux between 1969 and 1980. The Lyman alpha flux at solar minimum is required in the model and is taken as 2.32 x 10 11 photons/cm 2 /s. This value occurred during 1975 as well as in 1976 near the commencement of solar cycle 21. The model predicts that the Lyman alpha flux increases to as much as 5 x 10 11 photons/cm 2 /s at the maximum of the solar cycle. The ratio of the average fluxes for December 1979 (cycle maximum) and July 1976 (cycle minimum) is 1.9. During solar maximum the 27-day solar rotation is shown to cause the Lyman alpha flux to vary by as much as 40% or as little as 5%. The model also shows that the Lyman alpha flux varies over intermediate time periods of 2 to 3 years, as well as over the 11-year sunspot cycle. We conclude that, unlike the sunspot number and the 10.7-cm radio flux, the Lyman alpha flux had a variability that was approximately the same during each of the past three cycles. Lyman alpha fluxes calculated by the model are consistent with measurements of the Lyman alpha flux made by 11 of a total of 14 rocket experiments conducted during the period 1969--1980. The model explains satisfactorily the absolute magnitude, long-term trends, and the cycle variability seen in the Lyman alpha irradiances by the OSO 5 satellite experiment. The 27-day variability observed by the AE-E satellite experiment is well reproduced. However, the magntidue of the AE-E 1 Lyman alpha irradiances are higher than the model calculations by between 40% and 80%. We suggest that the assumed calibration of the AE-E irradiances is in error

Astrophysical Applications of Gravitational Lensing

Science.gov (United States)

Mediavilla, Evencio; Muñoz, Jose A.; Garzón, Francisco; Mahoney, Terence J.

2016-10-01

Contributors; Participants; Preface; Acknowledgements; 1. Lensing basics Sherry H. Suyu; 2. Exoplanet microlensing Andrew Gould; 3. Case studies of microlensing Veronica Motta and Emilio Falco; 4. Microlensing of quasars and AGN Joachim Wambsganss; 5. DM in clusters and large-scale structure Peter Schneider; 6. The future of strong lensing Chris Fassnacht; 7. Methods for strong lens modelling Charles Keeton; 8. Tutorial on inverse ray shooting Jorge Jimenez-Vicente.

THE LYMAN ALPHA REFERENCE SAMPLE: EXTENDED LYMAN ALPHA HALOS PRODUCED AT LOW DUST CONTENT

Energy Technology Data Exchange (ETDEWEB)

Hayes, Matthew [Universite de Toulouse, UPS-OMP, IRAP, Toulouse (France); Oestlin, Goeran; Duval, Florent; Guaita, Lucia; Melinder, Jens; Sandberg, Andreas [Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Schaerer, Daniel [CNRS, IRAP, 14, avenue Edouard Belin, F-31400 Toulouse (France); Verhamme, Anne; Orlitova, Ivana [Geneva Observatory, University of Geneva, 51 Chemin des Maillettes, CH-1290 Versoix (Switzerland); Mas-Hesse, J. Miguel; Oti-Floranes, Hector [Centro de Astrobiologia (CSIC-INTA), Departamento de Astrofisica, POB 78, 28691 Villanueva de la Canada (Spain); Adamo, Angela [Max Planck Institute for Astronomy, Koenigstuhl 17, D-69117 Heidelberg (Germany); Atek, Hakim [Laboratoire d' Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Observatoire, CH-1290 Sauverny (Switzerland); Cannon, John M. [Department of Physics and Astronomy, Macalester College, 1600 Grand Avenue, Saint Paul, MN 55105 (United States); Herenz, E. Christian [Leibniz-Institut fuer Astrophysik (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany); Kunth, Daniel [Institut d' Astrophysique de Paris, UMR 7095 CNRS and UPMC, 98 bis Bd Arago, F-75014 Paris (France); Laursen, Peter, E-mail: matthew@astro.su.se [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark)

2013-03-10

We report on new imaging observations of the Lyman alpha emission line (Ly{alpha}), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample. We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Ly{alpha}, H{alpha}, and the far ultraviolet continuum. We show that Ly{alpha} is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20% radius, R{sub P20}, Ly{alpha} radii are larger than those of H{alpha} by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Ly{alpha}-to-FUV radii is 2.9. This suggests that much of the Ly{alpha} light is pushed to large radii by resonance scattering. Defining the Relative Petrosian Extension of Ly{alpha} compared to H{alpha}, {xi}{sub Ly{alpha}} = R {sup Ly{alpha}}{sub P20}/R {sup H{alpha}}{sub P20}, we find {xi}{sub Ly{alpha}} to be uncorrelated with total Ly{alpha} luminosity. However, {xi}{sub Ly{alpha}} is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Ly{alpha} photons throughout the interstellar medium and drive a large extended Ly{alpha} halo.

Strong gravitational lensing by a charged Kiselev black hole

Energy Technology Data Exchange (ETDEWEB)

Azreg-Ainou, Mustapha [Baskent University, Engineering Faculty, Ankara (Turkey); Bahamonde, Sebastian [University College London, Department of Mathematics, London (United Kingdom); Jamil, Mubasher [National University of Sciences and Technology (NUST), Department of Mathematics, School of Natural Sciences (SNS), Islamabad (Pakistan)

2017-06-15

We study the gravitational lensing scenario where the lens is a spherically symmetric charged black hole (BH) surrounded by quintessence matter. The null geodesic equations in the curved background of the black hole are derived. The resulting trajectory equation is solved analytically via perturbation and series methods for a special choice of parameters, and the distance of the closest approach to black hole is calculated. We also derive the lens equation giving the bending angle of light in the curved background. In the strong field approximation, the solution of the lens equation is also obtained for all values of the quintessence parameter w{sub q}. For all w{sub q}, we show that there are no stable closed null orbits and that corrections to the deflection angle for the Reissner-Nordstroem black hole when the observer and the source are at large, but finite, distances from the lens do not depend on the charge up to the inverse of the distances squared. A part of the present work, analyzed, however, with a different approach, is the extension of Younas et al. (Phys Rev D 92:084042, 2015) where the uncharged case has been treated. (orig.)

Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

Energy Technology Data Exchange (ETDEWEB)

Bayliss, Matthew B.; Bordoloi, Rongmon [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa [RSAA, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Gladders, Michael D. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Rigby, Jane R. [Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Dahle, Hakon [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Florian, Michael, E-mail: mbayliss@mit.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2017-08-20

We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

International Nuclear Information System (INIS)

Bayliss, Matthew B.; Bordoloi, Rongmon; Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel; Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa; Gladders, Michael D.; Rigby, Jane R.; Dahle, Hakon; Florian, Michael

2017-01-01

We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

CENTRAL DARK MATTER TRENDS IN EARLY-TYPE GALAXIES FROM STRONG LENSING, DYNAMICS, AND STELLAR POPULATIONS

International Nuclear Information System (INIS)

Tortora, C.; Jetzer, P.; Napolitano, N. R.; Romanowsky, A. J.

2010-01-01

We analyze the correlations between central dark matter (DM) content of early-type galaxies and their sizes and ages, using a sample of intermediate-redshift (z ∼ 0.2) gravitational lenses from the SLACS survey, and by comparing them to a larger sample of z ∼ 0 galaxies. We decompose the deprojected galaxy masses into DM and stellar components using combinations of strong lensing, stellar dynamics, and stellar populations modeling. For a given stellar mass, we find that for galaxies with larger sizes, the DM fraction increases and the mean DM density decreases, consistently with the cuspy halos expected in cosmological formation scenarios. The DM fraction also decreases with stellar age, which can be partially explained by the inverse correlation between size and age. The residual trend may point to systematic dependencies on formation epoch of halo contraction or stellar initial mass functions. These results are in agreement with recent findings based on local galaxies by Napolitano et al. and suggest negligible evidence of galaxy evolution over the last ∼2.5 Gyr other than passive stellar aging.

The Master Lens Database and The Orphan Lenses Project

Science.gov (United States)

Moustakas, Leonidas

2012-10-01

Strong gravitational lenses are uniquely suited for the study of dark matter structure and substructure within massive halos of many scales, act as gravitational telescopes for distant faint objects, and can give powerful and competitive cosmological constraints. While hundreds of strong lenses are known to date, spanning five orders of magnitude in mass scale, thousands will be identified this decade. To fully exploit the power of these objects presently, and in the near future, we are creating the Master Lens Database. This is a clearinghouse of all known strong lens systems, with a sophisticated and modern database of uniformly measured and derived observational and lens-model derived quantities, using archival Hubble data across several instruments. This Database enables new science that can be done with a comprehensive sample of strong lenses. The operational goal of this proposal is to develop the process and the code to semi-automatically stage Hubble data of each system, create appropriate masks of the lensing objects and lensing features, and derive gravitational lens models, to provide a uniform and fairly comprehensive information set that is ingested into the Database. The scientific goal for this team is to use the properties of the ensemble of lenses to make a new study of the internal structure of lensing galaxies, and to identify new objects that show evidence of strong substructure lensing, for follow-up study. All data, scripts, masks, model setup files, and derived parameters, will be public, and free. The Database will be accessible online and through a sophisticated smartphone application, which will also be free.

Mass density slope of elliptical galaxies from strong lensing and resolved stellar kinematics

Science.gov (United States)

Lyskova, N.; Churazov, E.; Naab, T.

2018-04-01

We discuss constraints on the mass density distribution (parametrized as ρ ∝ r-γ) in early-type galaxies provided by strong lensing and stellar kinematics data. The constraints come from mass measurements at two `pinch' radii. One `pinch' radius r1 = 2.2REinst is defined such that the Einstein (i.e. aperture) mass can be converted into the spherical mass almost independently of the mass-model. Another `pinch' radius r2 = Ropt is chosen so that the dynamical mass, derived from the line-of-sight velocity dispersion, is least sensitive to the anisotropy of stellar orbits. We verified the performance of this approach on a sample of simulated elliptical galaxies and on a sample of 15 SLACS lens galaxies at 0.01 ≤ z ≤ 0.35, which have already been analysed in Barnabè et al. by the self-consistent joint lensing and kinematic code. For massive simulated galaxies, the density slope γ is recovered with an accuracy of ˜13 per cent, unless r1 and r2 happen to be close to each other. For SLACS galaxies, we found good overall agreement with the results of Barnabè et al. with a sample-averaged slope γ = 2.1 ± 0.05. Although the two-pinch-radii approach has larger statistical uncertainties, it is much simpler and uses only few arithmetic operations with directly observable quantities.

Fragmentation inside atomic cooling haloes exposed to Lyman-Werner radiation

Science.gov (United States)

Regan, John A.; Downes, Turlough P.

2018-04-01

Supermassive stars born in pristine environments in the early Universe hold the promise of being the seeds for the supermassive black holes observed as high redshift quasars shortly after the epoch of reionisation. H2 suppression is thought to be crucial in order to negate normal Population III star formation and allow high accretion rates to drive the formation of supermassive stars. Only in the cases where vigorous fragmentation is avoided will a monolithic collapse be successful, giving rise to a single massive central object. We investigate the number of fragmentation sites formed in collapsing atomic cooling haloes subject to various levels of background Lyman-Werner flux. The background Lyman-Werner flux manipulates the chemical properties of the gas in the collapsing halo by destroying H2. We find that only when the collapsing gas cloud shifts from the molecular to the atomic cooling regime is the degree of fragmentation suppressed. In our particular case, we find that this occurs above a critical Lyman-Werner background of J ˜ 10 J21. The important criterion being the transition to the atomic cooling regime rather than the actual value of J, which will vary locally. Once the temperature of the gas exceeds T ≳ 104 K and the gas transitions to atomic line cooling, then vigorous fragmentation is strongly suppressed.

J0454-0309: evidence of a strong lensing fossil group falling into a poor galaxy cluster

Science.gov (United States)

Schirmer, M.; Suyu, S.; Schrabback, T.; Hildebrandt, H.; Erben, T.; Halkola, A.

2010-05-01

Aims: We have discovered a strong lensing fossil group (J0454) projected near the well-studied cluster MS0451-0305. Using the large amount of available archival data, we compare J0454 to normal groups and clusters. A highly asymmetric image configuration of the strong lens enables us to study the substructure of the system. Methods: We used multicolour Subaru/Suprime-Cam and CFHT/Megaprime imaging, together with Keck spectroscopy to identify member galaxies. A VLT/FORS2 spectrum was taken to determine the redshifts of the brightest elliptical and the lensed arc. Using HST/ACS images, we determined the group's weak lensing signal and modelled the strong lens system. This is the first time that a fossil group is analysed with lensing methods. The X-ray luminosity and temperature were derived from XMM-Newton data. Results: J0454 is located at z = 0.26, with a gap of 2.5 mag between the brightest and second brightest galaxies within half the virial radius. Outside a radius of 1.5 Mpc, we find two filaments extending over 4 Mpc, and within we identify 31 members spectroscopically and 33 via the red sequence with i systems, a sparse cluster and an infalling fossil group, where the latter seeds the brightest cluster galaxy. An alternative to the sparse cluster could be a filament projected along the line of sight mimicking a cluster, with galaxies streaming towards the fossil group. This work is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan; based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii; based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile (ESO DDT

SUB-KILOPARSEC IMAGING OF COOL MOLECULAR GAS IN TWO STRONGLY LENSED DUSTY, STAR-FORMING GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Spilker, J. S.; Marrone, D. P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Aravena, M. [Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago (Chile); Béthermin, M.; Breuck, C. de [European Southern Observatory, Karl Schwarzschild Straße 2, D-85748 Garching (Germany); Bothwell, M. S. [Cavendish Laboratory, University of Cambridge, JJ Thompson Ave, Cambridge CB3 0HA (United Kingdom); Carlstrom, J. E. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Chapman, S. C.; Rotermund, K. M. [Dalhousie University, Halifax, Nova Scotia (Canada); Collier, J. D.; Galvin, T.; Grieve, K.; O’Brien, A. [University of Western Sydney, Locked Bag 1797, Penrith, NSW 2751 (Australia); Fassnacht, C. D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Gonzalez, A. H.; Ma, J. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); González-López, J. [Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Av. Vicuña Mackenna 4860, 782-0436 Macul, Santiago (Chile); Hezaveh, Y. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States); Malkan, M., E-mail: jspilker@as.arizona.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); and others

2015-10-01

We present spatially resolved imaging obtained with the Australia Telescope Compact Array (ATCA) of three CO lines in two high-redshift gravitationally lensed dusty star-forming galaxies, discovered by the South Pole Telescope. Strong lensing allows us to probe the structure and dynamics of the molecular gas in these two objects, at z = 2.78 and z = 5.66, with effective source-plane resolution of less than 1 kpc. We model the lensed emission from multiple CO transitions and the dust continuum in a consistent manner, finding that the cold molecular gas as traced by low-J CO always has a larger half-light radius than the 870 μm dust continuum emission. This size difference leads to up to 50% differences in the magnification factor for the cold gas compared to dust. In the z = 2.78 galaxy, these CO observations confirm that the background source is undergoing a major merger, while the velocity field of the other source is more complex. We use the ATCA CO observations and comparable resolution Atacama Large Millimeter/submillimeter Array dust continuum imaging of the same objects to constrain the CO–H{sub 2} conversion factor with three different procedures, finding good agreement between the methods and values consistent with those found for rapidly star-forming systems. We discuss these galaxies in the context of the star formation—gas mass surface density relation, noting that the change in emitting area with observed CO transition must be accounted for when comparing high-redshift galaxies to their lower redshift counterparts.

DISCOVERY OF A STRONG LENSING GALAXY EMBEDDED IN A CLUSTER AT z = 1.62

International Nuclear Information System (INIS)

Wong, Kenneth C.; Suyu, Sherry H.; Tran, Kim-Vy H.; Papovich, Casey J.; Momcheva, Ivelina G.; Brammer, Gabriel B.; Koekemoer, Anton M.; Brodwin, Mark; Gonzalez, Anthony H.; Kacprzak, Glenn G.; Rudnick, Gregory H.; Halkola, Aleksi

2014-01-01

We identify a strong lensing galaxy in the cluster IRC 0218 (also known as XMM-LSS J02182–05102) that is spectroscopically confirmed to be at z = 1.62, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be z S = 2.26. Using HST imaging in ACS/F475W, ACS/F814W, WFC3/F125W, and WFC3/F160W, we model the lens mass distribution with an elliptical power-law profile and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is θ E =0.38 −0.01 +0.02 arcsec (3.2 −0.1 +0.2 kpc) and the total enclosed mass is M tot (<θ E )=1.8 −0.1 +0.2 ×10 11 M ⊙ . We estimate that the cluster environment contributes ∼10% of this total mass. Assuming a Chabrier initial mass function (IMF), the dark matter fraction within θ E is f DM Chab =0.3 −0.3 +0.1 , while a Salpeter IMF is marginally inconsistent with the enclosed mass (f DM Salp =−0.3 −0.5 +0.2 ). The total magnification of the source is μ tot =2.1 −0.3 +0.4 . The source has at least one bright compact region offset from the source center. Emission from Lyα and [O III] are likely to probe different regions in the source

Strong gravitational lensing and the stellar IMF of early-type galaxies

Science.gov (United States)

Leier, Dominik; Ferreras, Ignacio; Saha, Prasenjit; Charlot, Stéphane; Bruzual, Gustavo; La Barbera, Francesco

2016-07-01

Systematic variations of the initial mass function (IMF) in early-type galaxies, and their connection with possible drivers such as velocity dispersion or metallicity, have been much debated in recent years. Strong lensing over galaxy scales combined with photometric and spectroscopic data provides a powerful method to constrain the stellar mass-to-light ratio and hence the functional form of the IMF. We combine photometric and spectroscopic constraints from the latest set of population synthesis models of Charlot & Bruzual, including a varying IMF, with a non-parametric analysis of the lens masses of 18 ETGs from the SLACS survey, with velocity dispersions in the range 200-300 km s-1. We find that very bottom-heavy IMFs are excluded. However, the upper limit to the bimodal IMF slope (μ ≲ 2.2, accounting for a dark matter fraction of 20-30 per cent, where μ = 1.3 corresponds to a Kroupa-like IMF) is compatible at the 1σ level with constraints imposed by gravity-sensitive line strengths. A two-segment power-law parametrization of the IMF (Salpeter-like for high masses) is more constrained (Γ ≲ 1.5, where Γ is the power index at low masses) but requires a dark matter contribution of ≳25 per cent to reconcile the results with a Salpeter IMF. For a standard Milky Way-like IMF to be applicable, a significant dark matter contribution is required within 1Re. Our results reveal a large range of allowed IMF slopes, which, when interpreted as intrinsic scatter in the IMF properties of ETGs, could explain the recent results of Smith et al., who find Milky Way-like IMF normalizations in a few massive lensing ETGs.

A strong-lensing elliptical galaxy in the MaNGA survey

Science.gov (United States)

Smith, Russell J.

2017-01-01

I report discovery of a new galaxy-scale gravitational lens system, identified using public data from the Mapping Galaxies at Apache Point Observatory (MaNGA) survey, as part of a systematic search for lensed background line emitters. The lens is SDSS J170124.01+372258.0, a giant elliptical galaxy with velocity dispersion σ = 256 km s-1, at a redshift of zl = 0.122. After modelling and subtracting the target galaxy light, the integral-field data cube reveals [O II], [O III] and Hβ emission lines corresponding to a source at zs = 0.791, forming an identifiable ring around the galaxy centre. If the ring is formed by a single lensed source, then the Einstein radius is REin ≈ 2.3 arcsec, projecting to ˜5 kpc at the distance of the lens. The total projected lensing mass is MEin = (3.6 ± 0.6) × 1011 M⊙, and the total J-band mass-to-light ratio is 3.0 ± 0.7 solar units. Plausible estimates of the likely dark matter content could reconcile this with a Milky Way-like initial mass function (IMF), for which M/L ≈ 1.5 is expected, but heavier IMFs are by no means excluded with the present data. An alternative interpretation of the system, with a more complex source plane, is also discussed. The discovery of this system bodes well for future lens searches based on MaNGA and other integral-field spectroscopic surveys.

Investigations of Galaxy Clusters Using Gravitational Lensing

Energy Technology Data Exchange (ETDEWEB)

Wiesner, Matthew P. [Northern Illinois Univ., DeKalb, IL (United States)

2014-08-01

In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

Discovery of three strongly lensed quasars in the Sloan Digital Sky Survey

Science.gov (United States)

Williams, P. R.; Agnello, A.; Treu, T.; Abramson, L. E.; Anguita, T.; Apostolovski, Y.; Chen, G. C.-F.; Fassnacht, C. D.; Hsueh, J. W.; Lemaux, B. C.; Motta, V.; Oldham, L.; Rojas, K.; Rusu, C. E.; Shajib, A. J.; Wang, X.

2018-06-01

We present the discovery of three quasar lenses in the Sloan Digital Sky Survey, selected using two novel photometry-based selection techniques. The J0941+0518 system, with two point sources separated by 5.46 arcsec on either side of a galaxy, has source and lens redshifts 1.54 and 0.343. Images of J2257+2349 show two point sources separated by 1.67 arcsec on either side of an E/S0 galaxy. The extracted spectra show two images of the same quasar at zs = 2.10. SDSS J1640+1045 has two quasar spectra at zs = 1.70 and fits to the SDSS and Pan-STARRS images confirm the presence of a galaxy between the two point sources. We observed 56 photometrically selected lens candidates in this follow-up campaign, confirming three new lenses, re-discovering one known lens, and ruling out 36 candidates, with 16 still inconclusive. This initial campaign demonstrates the power of purely photometric selection techniques in finding lensed quasars.

DISCOVERY OF A STRONG LENSING GALAXY EMBEDDED IN A CLUSTER AT z = 1.62

Energy Technology Data Exchange (ETDEWEB)

Wong, Kenneth C.; Suyu, Sherry H. [Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), P.O. Box 23-141, Taipei 10617, Taiwan (China); Tran, Kim-Vy H.; Papovich, Casey J. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Momcheva, Ivelina G. [Astronomy Department, Yale University, New Haven, CT 06511 (United States); Brammer, Gabriel B.; Koekemoer, Anton M. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Brodwin, Mark [Department of Physics and Astronomy, University of Missouri, 5110 Rockhill Road, Kansas City, MO 64110 (United States); Gonzalez, Anthony H. [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Rudnick, Gregory H. [Department of Physics and Astronomy, The University of Kansas, Malott Room 1082, 1251 Wescoe Hall Drive, Lawrence, KS 66045 (United States); Halkola, Aleksi

2014-07-10

We identify a strong lensing galaxy in the cluster IRC 0218 (also known as XMM-LSS J02182–05102) that is spectroscopically confirmed to be at z = 1.62, making it the highest-redshift strong lens galaxy known. The lens is one of the two brightest cluster galaxies and lenses a background source galaxy into an arc and a counterimage. With Hubble Space Telescope (HST) grism and Keck/LRIS spectroscopy, we measure the source redshift to be z {sub S} = 2.26. Using HST imaging in ACS/F475W, ACS/F814W, WFC3/F125W, and WFC3/F160W, we model the lens mass distribution with an elliptical power-law profile and account for the effects of the cluster halo and nearby galaxies. The Einstein radius is θ{sub E}=0.38{sub −0.01}{sup +0.02} arcsec (3.2{sub −0.1}{sup +0.2} kpc) and the total enclosed mass is M {sub tot}(<θ{sub E})=1.8{sub −0.1}{sup +0.2}×10{sup 11} M{sub ⊙}. We estimate that the cluster environment contributes ∼10% of this total mass. Assuming a Chabrier initial mass function (IMF), the dark matter fraction within θ{sub E} is f{sub DM}{sup Chab}=0.3{sub −0.3}{sup +0.1}, while a Salpeter IMF is marginally inconsistent with the enclosed mass (f{sub DM}{sup Salp}=−0.3{sub −0.5}{sup +0.2}). The total magnification of the source is μ{sub tot}=2.1{sub −0.3}{sup +0.4}. The source has at least one bright compact region offset from the source center. Emission from Lyα and [O III] are likely to probe different regions in the source.

A STRONGLY LENSED MASSIVE ULTRACOMPACT QUIESCENT GALAXY AT z ∼ 2.4 IN THE COSMOS/UltraVISTA FIELD

International Nuclear Information System (INIS)

Muzzin, Adam; Labbé, Ivo; Franx, Marijn; Holt, J.; Szomoru, Daniel; Van de Sande, Jesse; Van Dokkum, Pieter; Brammer, Gabriel; Marchesini, Danilo; Stefanon, Mauro; Buitrago, F.; Dunlop, James; Caputi, K. I.; Fynbo, J. P. U.; Milvang-Jensen, Bo; Le Févre, Olivier; McCracken, Henry J.

2012-01-01

We report the discovery of a massive ultracompact quiescent galaxy that has been strongly lensed into multiple images by a foreground galaxy at z 0.960. This system was serendipitously discovered as a set of extremely K s -bright high-redshift galaxies with red J – K s colors using new data from the UltraVISTA YJHK s near-infrared survey. The system was also previously identified as an optically faint lens/source system using the COSMOS Advanced Camera for Surveys (ACS) imaging by Faure et al. Photometric redshifts for the three brightest images of the source galaxy determined from 27-band photometry place the source at z = 2.4 ± 0.1. We provide an updated lens model for the system that is a good fit to the positions and morphologies of the galaxies in the ACS image. The lens model implies that the magnification of the three brightest images is a factor of 4-5. We use the lens model, combined with the K s -band image, to constrain the size and Sérsic profile of the galaxy. The best-fit model is an ultracompact galaxy (R e = 0.64 +0.08 –0.18 kpc, lensing-corrected), with a Sérsic profile that is intermediate between a disk and a bulge profile (n 2.2 +2.3 – 0 .9 ), albeit with considerable uncertainties on the Sérsic profile. We present aperture photometry for the source galaxy images that have been corrected for flux contamination from the central lens. The best-fit stellar population model is a massive galaxy (log(M star /M ☉ ) = 10.8 +0.1 –0.1 , lensing-corrected) with an age of 1.0 +1.0 –0.4 Gyr, moderate dust extinction (A v = 0.8 +0.5 –0.6 ), and a low specific star formation rate (log(SSFR) –1 ). This is typical of massive ''red-and-dead'' galaxies at this redshift and confirms that this source is the first bona fide strongly lensed massive ultracompact quiescent galaxy to be discovered. We conclude with a discussion of the prospects of finding a larger sample of these galaxies.

Continuous coherent Lyman-alpha excitation of atomic hydrogen.

NARCIS (Netherlands)

Eikema, K.S.E.; Waltz, J.; Hänsch, T.

2001-01-01

The first near natural linewidth of the 1S-2P transition in atomic hydrogen was reported with a high degree of accuracy. A high yield of continuous Lyman-α radiation based on four wave mixing in mercury was employed. It was shown that laser cooloing and detection with Lyman-α radiation has excellent

Strong lensing analysis of PLCK G004.5-19.5, a Planck-discovered cluster hosting a radio relic at z = 0.52

Science.gov (United States)

Sifón, Cristóbal; Menanteau, Felipe; Hughes, John P.; Carrasco, Mauricio; Barrientos, L. Felipe

2014-02-01

Context. The recent discovery of a large number of galaxy clusters using the Sunyaev-Zel'dovich (SZ) effect has opened a new era on the study of the most massive clusters in the Universe. Multiwavelength analyses are required to understand the properties of these new sets of clusters, which are a sensitive probe of cosmology. Aims: We aim for a multiwavelength characterization of PLCK G004.5-19.5, one of the most massive X-ray validated SZ effect-selected galaxy clusters discovered by the Planck satellite. Methods: We have observed PLCK G004.5-19.5 with GMOS on the 8.1 m-Gemini South Telescope for optical imaging and spectroscopy, and performed a strong lensing analysis. We also searched for associated radio emission in published catalogs. Results: An analysis of the optical images confirms that this is a massive cluster, with a dominant central galaxy and an accompanying red sequence of galaxies, plus a 14″-long strong lensing arc. Longslit spectroscopy of six cluster members shows that the cluster is at z = 0.516 ± 0.002. We also targeted the strongly lensed arc, and found zarc = 1.601. We use LensTool to carry out a strong lensing analysis, from which we measure a median Einstein radius θE(zs = 1.6) ≃ 30″ and estimate an enclosed mass ME = 2.45-0.47+0.45 × 1014 M⊙. By extrapolating a Navarro-Frenk-White profile, we find a total mass M500SL = 4.0-1.0+2.1 × 1014 M⊙. We also include a constraint on the mass from previous X-ray observations, which yields a slightly higher mass, M500SL+X = 6.7-1.3+2.6 × 1014 M⊙, consistent with the value from strong lensing alone. Intermediate-resolution radio images from the TIFR GMRT Sky Survey at 150 MHz reveal that PLCK G004.5-19.5 hosts a powerful radio relic on scales ≲500 kpc. Emission at the same location is also detected in low-resolution images at 843 MHz and 1.4 GHz. This is one of the higher redshift radio relics known to date. Based on observations obtained at the Gemini Observatory, which is operated

Lyman alpha SMM/UVSP absolute calibration and geocoronal correction

Science.gov (United States)

Fontenla, Juan M.; Reichmann, Edwin J.

1987-01-01

Lyman alpha observations from the Ultraviolet Spectrometer Polarimeter (UVSP) instrument of the Solar Maximum Mission (SMM) spacecraft were analyzed and provide instrumental calibration details. Specific values of the instrument quantum efficiency, Lyman alpha absolute intensity, and correction for geocoronal absorption are presented.

Characterization of sand lenses embedded in tills

DEFF Research Database (Denmark)

Kessler, Timo Christian; Klint, K.E.S.; Nilsson, B.

2012-01-01

Tills dominate large parts of the superficial sediments on the Northern hemisphere. These glacial diamictons are extremely heterogeneous and riddled with fractures and lenses of sand or gravel. The frequency and geometry of sand lenses within tills are strongly linked to glaciodynamic processes...

Lyman continuum observations of solar flares

Science.gov (United States)

Machado, M. E.; Noyes, R. W.

1978-01-01

A study is made of Lyman continuum observations of solar flares, using data obtained by the EUV spectroheliometer on the Apollo Telescope Mount. It is found that there are two main types of flare regions: an overall 'mean' flare coincident with the H-alpha flare region, and transient Lyman continuum kernels which can be identified with the H-alpha and X-ray kernels observed by other authors. It is found that the ground level hydrogen population in flares is closer to LTE than in the quiet sun and active regions, and that the level of Lyman continuum formation is lowered in the atmosphere from a mass column density .000005 g/sq cm in the quiet sun to .0003 g/sq cm in the mean flare, and to .001 g/sq cm in kernels. From these results the amount of chromospheric material 'evaporated' into the high temperature region is derived, which is found to be approximately 10 to the 15th g, in agreement with observations of X-ray emission measures.

Rest-Frame Optical Spectra of Three Strongly Lensed Galaxies at z ~ 2

Science.gov (United States)

Hainline, Kevin N.; Shapley, Alice E.; Kornei, Katherine A.; Pettini, Max; Buckley-Geer, Elizabeth; Allam, Sahar S.; Tucker, Douglas L.

2009-08-01

We present Keck II NIRSPEC rest-frame optical spectra for three recently discovered lensed galaxies: the Cosmic Horseshoe (z = 2.38), the Clone (z = 2.00), and SDSS J090122.37+181432.3 (z = 2.26). The boost in signal-to-noise ratio (S/N) from gravitational lensing provides an unusually detailed view of the physical conditions in these objects. A full complement of high S/N rest-frame optical emission lines is measured, spanning from rest frame 3600 to 6800 Å, including robust detections of fainter lines such as Hγ, [S II]λ6717,6732, and in one instance [Ne III]λ3869. SDSS J090122.37+181432.3 shows evidence for active galactic nucleus activity, and therefore we focus our analysis on star-forming regions in the Cosmic Horseshoe and the Clone. For these two objects, we estimate a wide range of physical properties. Current lensing models for the Cosmic Horseshoe and the Clone allow us to correct the measured Hα luminosity and calculated star formation rate. Metallicities have been estimated with a variety of indicators, which span a range of values of 12+ log(O/H) = 8.3-8.8, between ~0.4 and ~1.5 of the solar oxygen abundance. Dynamical masses were computed from the Hα velocity dispersions and measured half-light radii of the reconstructed sources. A comparison of the Balmer lines enabled measurement of dust reddening coefficients. Variations in the line ratios between the different lensed images are also observed, indicating that the spectra are probing different regions of the lensed galaxies. In all respects, the lensed objects appear fairly typical of ultraviolet-selected star-forming galaxies at z ~ 2. The Clone occupies a position on the emission-line diagnostic diagram of [O III]/Hβ versus [N II]/Hα that is offset from the locations of z ~ 0 galaxies. Our new NIRSPEC measurements may provide quantitative insights into why high-redshift objects display such properties. From the [S II] line ratio, high electron densities (~1000 cm-3) are inferred compared

Chandra and ALMA observations of the nuclear activity in two strongly lensed star-forming galaxies

Science.gov (United States)

Massardi, M.; Enia, A. F. M.; Negrello, M.; Mancuso, C.; Lapi, A.; Vignali, C.; Gilli, R.; Burkutean, S.; Danese, L.; Zotti, G. De

2018-02-01

Aim. According to coevolutionary scenarios, nuclear activity and star formation play relevant roles in the early stages of galaxy formation. We aim at identifying them in high-redshift galaxies by exploiting high-resolution and high-sensitivity X-ray and millimeter-wavelength data to confirm the presence or absence of star formation and nuclear activity and describe their relative roles in shaping the spectral energy distributions and in contributing to the energy budgets of the galaxies. Methods: We present the data, model, and analysis in the X-ray and millimeter (mm) bands for two strongly lensed galaxies, SDP.9 (HATLAS J090740.0-004200) and SDP.11 (HATLAS J091043.1-000322), which we selected in the Herschel-ATLAS catalogs for their excess emission in the mid-IR regime at redshift ≳1.5. This emission suggests nuclear activity in the early stages of galaxy formation. We observed both of them with Chandra ACIS-S in the X-ray regime and analyzed the high-resolution mm data that are available in the ALMA Science Archive for SDP.9. By combining the information available in mm, optical, and X-ray bands, we reconstructed the source morphology. Results: Both targets were detected in the X-ray, which strongly indicates highly obscured nuclear activity. ALMA observations for SDP.9 for the continuum and CO(6-5) spectral line with high resolution (0.02 arcsec corresponding to 65 pc at the distance of the galaxy) allowed us to estimate the lensed galaxy redshift to a better accuracy than pre-ALMA estimates (1.5753 ± 0.0003) and to model the emission of the optical, millimetric, and X-ray band for this galaxy. We demonstrate that the X-ray emission is generated in the nuclear environment, which strongly supports that this object has nuclear activity. On the basis of the X-ray data, we attempt an estimate of the black hole properties in these galaxies. Conclusions: By taking advantage of the lensing magnification, we identify weak nuclear activity associated with high

Lyman continuum escape fraction of faint galaxies at z 3.3 in the CANDELS/GOODS-North, EGS, and COSMOS fields with LBC

Science.gov (United States)

Grazian, A.; Giallongo, E.; Paris, D.; Boutsia, K.; Dickinson, M.; Santini, P.; Windhorst, R. A.; Jansen, R. A.; Cohen, S. H.; Ashcraft, T. A.; Scarlata, C.; Rutkowski, M. J.; Vanzella, E.; Cusano, F.; Cristiani, S.; Giavalisco, M.; Ferguson, H. C.; Koekemoer, A.; Grogin, N. A.; Castellano, M.; Fiore, F.; Fontana, A.; Marchi, F.; Pedichini, F.; Pentericci, L.; Amorín, R.; Barro, G.; Bonchi, A.; Bongiorno, A.; Faber, S. M.; Fumana, M.; Galametz, A.; Guaita, L.; Kocevski, D. D.; Merlin, E.; Nonino, M.; O'Connell, R. W.; Pilo, S.; Ryan, R. E.; Sani, E.; Speziali, R.; Testa, V.; Weiner, B.; Yan, H.

2017-06-01

Context. The reionization of the Universe is one of the most important topics of present-day astrophysical research. The most plausible candidates for the reionization process are star-forming galaxies, which according to the predictions of the majority of the theoretical and semi-analytical models should dominate the H I ionizing background at z ≳ 3. Aims: We measure the Lyman continuum escape fraction, which is one of the key parameters used to compute the contribution of star-forming galaxies to the UV background. It provides the ratio between the photons produced at λ ≤ 912 Å rest-frame and those that are able to reach the inter-galactic medium, I.e. that are not absorbed by the neutral hydrogen or by the dust of the galaxy's inter-stellar medium. Methods: We used ultra-deep U-band imaging (U = 30.2 mag at 1σ) from Large Binocular Camera at the Large Binocular Telescope (LBC/LBT) in the CANDELS/GOODS-North field and deep imaging in the COSMOS and EGS fields in order to estimate the Lyman continuum escape fraction of 69 star-forming galaxies with secure spectroscopic redshifts at 3.27 ≤ z ≤ 3.40 to faint magnitude limits (L = 0.2L∗, or equivalently M1500 - 19). The narrow redshift range implies that the LBC U-band filter exclusively samples the λ ≤ 912 Å rest-frame wavelengths. Results: We measured through stacks a stringent upper limit (L∗), while for the faint population (L = 0.2L∗) the limit to the escape fraction is ≲ 10%. We computed the contribution of star-forming galaxies to the observed UV background at z 3 and find that it is not sufficient to keep the Universe ionized at these redshifts unless their escape fraction increases significantly (≥ 10%) at low luminosities (M1500 ≥ - 19). Conclusions: We compare our results on the Lyman continuum escape fraction of high-z galaxies with recent estimates in the literature, and discuss future prospects to shed light on the end of the Dark Ages. In the future, strong gravitational

A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

Science.gov (United States)

Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.; Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.; Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway, T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère, F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos, A.; Štěpán, J.; Carlsson, M.

2014-10-01

A sounding-rocket experiment called the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is presently under development to measure the linear polarization profiles in the hydrogen Lyman-alpha (Lyα) line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim for first detection of the linear polarizations caused by scattering processes and the Hanle effect in the Lyα line with high accuracy (0.1%). This is a fist step for exploration of magnetic fields in the upper chromosphere and transition region of the Sun. Accurate measurements of the linear polarization signals caused by scattering processes and the Hanle effect in strong UV lines like Lyα are essential to explore with future solar telescopes the strength and structures of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP proposal has been accepted by NASA in 2012, and the flight is planned in 2015.

EDITORIAL: Focus on Gravitational Lensing

Science.gov (United States)

Jain, Bhuvnesh

2007-11-01

Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

Galex Lyman-alpha Emitters: Physical Properties, Luminosity Bimodality, And Morphologies.

Science.gov (United States)

Mallery, Ryan P.

2010-01-01

The Galaxy Evolution Explorer spectroscopic survey has uncovered a large statistically significant sample of Lyman-alpha emitters at z sim0.3. ACS imaging of these sources in the COSMOS and AEGIS deep fields reveals that these Lyman-alpha emitters consist of two distinct galaxy morphologies, face on spiral galaxies and compact starburst/merging systems. The morphology bimodality also results in a bimodal distribution of optical luminosity. A comparison between the UV photometry and MIPS 24 micron detections of these sources indicates that they are bluer, and have less dust extinction than similar star forming galaxies that lack Lyman-alpha detection. Our findings show how the global gas and dust distribution of star forming galaxies inhibits Lyman-alpha emission in star forming galaxies. GALEX is a NASA Small Explorer, launched in April 2003. We gratefully acknowledge NASA's support for construction, operation, and science analysis for the GALEX mission, developed in cooperation with the CNES of France and the Korean Ministry of Science and Technology.

Lyman series profiles: From laser-plasmas to white dwarf stars

Energy Technology Data Exchange (ETDEWEB)

Kielkopf, J.F. [University of Louisville, Louisville, Kentucky 40292 (United States); Allard, N.F. [Observatoire de Paris-Meudon, France and Institut d Astrophysique, Paris (France)

1999-04-01

The low energy interactions of neutral and ionized hydrogen atoms are fundamental processes which also have important applications to the diagnostics of laboratory and astrophysical plasmas. Satellites in the far wings of Lyman {alpha} and Lyman {beta} have been identified as ultraviolet absorption features in the spectra of white dwarf and {lambda} Bootis stars, and they are seen in the emission spectra of plasmas produced when a pulsed laser excites a target H{sub 2} gas. The observed Lyman series profiles agree with unified line shape theory which includes variation of the dipole transition moment during the radiative collision. {copyright} {ital 1999 American Institute of Physics.}

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

International Nuclear Information System (INIS)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora

2017-01-01

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N fluid , will be improved by an order of magnitude compared to current bounds.

Weighing the Low-Redshift Lyman-alpha Forest

Science.gov (United States)

Shull, Mike

2005-01-01

In 2003-2004, our FUSE research group prepared several major surveys of the amount of baryonic matter in the intergalactic medium (IGM), using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. These surveys include measurements of the Lyman-alpha absorption line of neutral hydrogen (H I), the far-ultraviolet (1032,1038 Angstrom) doublet of highly ionized oxygen ( O VI), the higher Lyman-series lines (Ly-beta, Ly-gamma, etc) of H I, and the 977 Angstrom line of c III. As an overview, our FUSE spectroscopic studies, taken together with data from the Hubble Space Telescope, show that approximately 30% of the normal matter is contained in intergalactic hydrogen gas clouds (the Lyman-alpha forest). Another 5-10% resides in hotter gas at temperatures of 10(exp 5) to 10(exp 6) K, visible in 0 VI and C III absorption. Along with the matter attributed to galaxies, we have now accounted for approximately HALF of all the baryonic matter in the universe. Where is the other half? That matter my exist in even hotter gas, invisible through the ultraviolet absorption lines, but perhaps detectable through X-ray absorption lines of more highly ionized oxygen and neon.

Chromospheric Lyman-alpha spectro-polarimeter (CLASP)

Science.gov (United States)

Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa, Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa, Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada, Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier; Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Auchère, Frédéric; Carlsson, Mats

2012-09-01

One of the biggest challenges in heliophysics is to decipher the magnetic structure of the solar chromosphere. The importance of measuring the chromospheric magnetic field is due to both the key role the chromosphere plays in energizing and structuring the outer solar atmosphere and the inability of extrapolation of photospheric fields to adequately describe this key boundary region. Over the last few years, significant progress has been made in the spectral line formation of UV lines as well as the MHD modeling of the solar atmosphere. It is found that the Hanle effect in the Lyman-alpha line (121.567 nm) is a most promising diagnostic tool for weaker magnetic fields in the chromosphere and transition region. Based on this groundbreaking research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) to NASA as a sounding rocket experiment, for making the first measurement of the linear polarization produced by scattering processes and the Hanle effect in the Lyman-alpha line (121.567 nm), and making the first exploration of the magnetic field in the upper chromosphere and transition region of the Sun. The CLASP instrument consists of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam spectrograph assembly with a grating working as a beam splitter, and an identical pair of reflective polarization analyzers each equipped with a CCD camera. We propose to launch CLASP in December 2014.

THE SLOAN BRIGHT ARCS SURVEY: TEN STRONG GRAVITATIONAL LENSING CLUSTERS AND EVIDENCE OF OVERCONCENTRATION

Energy Technology Data Exchange (ETDEWEB)

Wiesner, Matthew P. [Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); Lin, Huan; Allam, Sahar S.; Annis, James; Buckley-Geer, Elizabeth J.; Diehl, H. Thomas; Kubik, Donna; Kubo, Jeffrey M.; Tucker, Douglas [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States)

2012-12-10

We describe 10 strong lensing galaxy clusters of redshift 0.26 {<=} z {<=} 0.56 that were found in the Sloan Digital Sky Survey. We present measurements of richness (N{sub 200}), mass (M{sub 200}), and velocity dispersion for the clusters. We find that in order to use the mass-richness relation from Johnston et al., which was established at mean redshift of 0.25, it is necessary to scale measured richness values up by 1.47. Using this scaling, we find richness values for these clusters to be in the range of 22 {<=} N{sub 200} {<=} 317 and mass values to be in the range of 1 Multiplication-Sign 10{sup 14} h {sup -1} M{sub Sun} {<=} M{sub 200} {<=} 30 Multiplication-Sign 10{sup 14} h {sup -1} M{sub Sun }. We also present measurements of Einstein radius, mass, and velocity dispersion for the lensing systems. The Einstein radii ({theta}{sub E}) are all relatively small, with 5.''4 {<=} {theta}{sub E} {<=} 13''. Finally, we consider if there is evidence that our clusters are more concentrated than {Lambda}CDM would predict. We find that six of our clusters do not show evidence of overconcentration, while four of our clusters do. We note a correlation between overconcentration and mass, as the four clusters showing evidence of overconcentration are all lower-mass clusters. For the four lowest mass clusters the average value of the concentration parameter c{sub 200} is 11.6, while for the six higher-mass clusters the average value of c{sub 200} is 4.4. {Lambda}CDM would place c{sub 200} between 3.4 and 5.7.

Direct Detection of The Lyman Continuum of Star-forming Galaxies at z~3

Science.gov (United States)

Vasei, Kaveh; Siana, Brian; Shapley, Alice; Alavi, Anahita; Rafelski, Marc

2018-01-01

Star-forming galaxies are widely believed to be responsible for the reionization of the Universe and much of the ionizing background at z>3. Therefore, there has been much interest in quantifying the escape fraction of the Lyman continuum (LyC) radiation of the star-forming galaxies. Yet direct detection of LyC has proven to be exceptionally challenging. Despite numerous efforts only 7 galaxies at z2 have been robustly confirmed as LyC leakers. To avoid these challenges many studies use indirect methods to infer the LyC escape fraction. We tested these indirect methods by attempting to detect escaping LyC with a 10-orbit Hubble near-UV (F275W) image that is just below the Lyman limit at the redshift of the Cosmic Horseshoe (a lensed galaxy at z=2.4). We concluded that the measured escape fraction is lower, by more than a factor of five, than the expected escape fraction based on the indirect methods. This emphasizes that indirect determinations should only be interpreted as upper-limits. We also investigated the deepest near-UV Hubble images of the SSA22 field to detect LyC leakage from a large sample of candidate star-forming galaxies at z~3.1, whose redshift was obtained by deep Keck/LRIS spectroscopy and for which Keck narrow-band imaging was showing possible LyC leakage. The high spatial resolution of Hubble images is crucial to confirm our detections are clean from foreground contaminating galaxies, and also to ascertain the escape fraction of our final candidates. We identify five clean LyC emitting star-forming galaxies. The follow up investigation of these galaxies will significantly increase our knowledge of the LyC escape fraction and the mechanisms allowing for LyC escape.

Relative Contribution of the Hydrogen 2 s Two-Photon Decay and Lyman- α Escape Channels during the Epoch of Cosmological Recombination

Science.gov (United States)

Rubiño-Martin, J. A.; Sunyaev, R. A.

2018-01-01

We discuss the evolution of the ratio in number of recombinations due to 2 s two photon escape and due to the escape of Lyman- α photons from the resonance during the epoch of cosmological recombination, within the width of the last scattering surface and near its boundaries. We discuss how this ratio evolves in time, and how it defines the profile of the Lyman- α line in the spectrum of CMB. One of the key reasons for explaining its time dependence is the strong overpopulation of the 2 p level relative to the 2 s level at redshifts z ≲ 750.

Herschel extreme lensing line observations: Dynamics of two strongly lensed star-forming galaxies near redshift z = 2

International Nuclear Information System (INIS)

Rhoads, James E.; Malhotra, Sangeeta; Allam, Sahar; Carilli, Chris; Combes, Françoise; Finkelstein, Keely; Finkelstein, Steven; Frye, Brenda; Gerin, Maryvonne; Guillard, Pierre; Nesvadba, Nicole; Rigby, Jane; Spaans, Marco; Strauss, Michael A.

2014-01-01

We report on two regularly rotating galaxies at redshift z ≈ 2, using high-resolution spectra of the bright [C II] 158 μm emission line from the HIFI instrument on the Herschel Space Observatory. Both SDSS090122.37+181432.3 ( S 0901 ) and SDSSJ120602.09+514229.5 ( t he Clone ) are strongly lensed and show the double-horned line profile that is typical of rotating gas disks. Using a parametric disk model to fit the emission line profiles, we find that S0901 has a rotation speed of vsin (i) ≈ 120 ± 7 km s –1 and a gas velocity dispersion of σ g < 23 km s –1 (1σ). The best-fitting model for the Clone is a rotationally supported disk having vsin (i) ≈ 79 ± 11 km s –1 and σ g ≲ 4 km s –1 (1σ). However, the Clone is also consistent with a family of dispersion-dominated models having σ g = 92 ± 20 km s –1 . Our results showcase the potential of the [C II] line as a kinematic probe of high-redshift galaxy dynamics: [C II] is bright, accessible to heterodyne receivers with exquisite velocity resolution, and traces dense star-forming interstellar gas. Future [C II] line observations with ALMA would offer the further advantage of spatial resolution, allowing a clearer separation between rotation and velocity dispersion.

Exploring a Potential Bias in Dark Matter Investigations Using Strongly Lensed Quasars

NARCIS (Netherlands)

Hsueh, Jen-Wei; Fassnacht, Christopher; Vegetti, Simona; Springola, Cristiana; Oldham, Lindsay; Despali, Giulia; Auger, Matthew; Xu, Dandan; Metcalf, Benton; McKean, John; Koopmans, Leon; Lagattuta, David

2018-01-01

Simulations based on ΛCDM cosmology predict thousands of substructures under galactic scale have not been detected in the local universe. One hypothesis proposes that most of these substructures are dark for various astrophysical reasons. Gravitational lensing provides a powerful alternative way to

QUANTIFYING THE BIASES OF SPECTROSCOPICALLY SELECTED GRAVITATIONAL LENSES

International Nuclear Information System (INIS)

Arneson, Ryan A.; Brownstein, Joel R.; Bolton, Adam S.

2012-01-01

Spectroscopic selection has been the most productive technique for the selection of galaxy-scale strong gravitational lens systems with known redshifts. Statistically significant samples of strong lenses provide a powerful method for measuring the mass-density parameters of the lensing population, but results can only be generalized to the parent population if the lensing selection biases are sufficiently understood. We perform controlled Monte Carlo simulations of spectroscopic lens surveys in order to quantify the bias of lenses relative to parent galaxies in velocity dispersion, mass axis ratio, and mass-density profile. For parameters typical of the SLACS and BELLS surveys, we find (1) no significant mass axis ratio detection bias of lenses relative to parent galaxies; (2) a very small detection bias toward shallow mass-density profiles, which is likely negligible compared to other sources of uncertainty in this parameter; (3) a detection bias toward smaller Einstein radius for systems drawn from parent populations with group- and cluster-scale lensing masses; and (4) a lens-modeling bias toward larger velocity dispersions for systems drawn from parent samples with sub-arcsecond mean Einstein radii. This last finding indicates that the incorporation of velocity-dispersion upper limits of non-lenses is an important ingredient for unbiased analyses of spectroscopically selected lens samples. In general, we find that the completeness of spectroscopic lens surveys in the plane of Einstein radius and mass-density profile power-law index is quite uniform, up to a sharp drop in the region of large Einstein radius and steep mass-density profile, and hence that such surveys are ideally suited to the study of massive field galaxies.

Development of Flight Slit-Jaw Optics for Chromospheric Lyman-Alpha SpectroPolarimeter

Science.gov (United States)

Kubo, Masahito; Suematsu, Yoshinori; Kano, Ryohei; Bando, Takamasa; Hara, Hirohisa; Narukage, Noriyuki; Katsukawa, Yukio; Ishikawa, Ryoko; Ishikawa, Shin-nosuke; Kobiki, Toshihiko;

Lensing of 21-cm fluctuations by primordial gravitational waves.

Science.gov (United States)

Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

2012-05-25

Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed.

Discovery of a very Lyman-α-luminous quasar at z = 6.62.

Science.gov (United States)

Koptelova, Ekaterina; Hwang, Chorng-Yuan; Yu, Po-Chieh; Chen, Wen-Ping; Guo, Jhen-Kuei

2017-02-02

Distant luminous quasars provide important information on the growth of the first supermassive black holes, their host galaxies and the epoch of reionization. The identification of quasars is usually performed through detection of their Lyman-α line redshifted to 0.9 microns at z > 6.5. Here, we report the discovery of a very Lyman-α luminous quasar, PSO J006.1240 + 39.2219 at redshift z = 6.618, selected based on its red colour and multi-epoch detection of the Lyman-α emission in a single near-infrared band. The Lyman-α line luminosity of PSO J006.1240 + 39.2219 is unusually high and estimated to be 0.8 × 10 12 Solar luminosities (about 3% of the total quasar luminosity). The Lyman-α emission of PSO J006.1240 + 39.2219 shows fast variability on timescales of days in the quasar rest frame, which has never been detected in any of the known high-redshift quasars. The high luminosity of the Lyman-α line, its narrow width and fast variability resemble properties of local Narrow-Line Seyfert 1 galaxies which suggests that the quasar is likely at the active phase of the black hole growth accreting close or even beyond the Eddington limit.

Wandering in the Lyman-alpha forest: a study of dark matter-dark radiation interactions

Energy Technology Data Exchange (ETDEWEB)

Krall, Rebecca; Cyr-Racine, Francis-Yan; Dvorkin, Cora, E-mail: rkrall@physics.harvard.edu, E-mail: fcyrraci@physics.harvard.edu, E-mail: dvorkin@physics.harvard.edu [Harvard University, Department of Physics, Cambridge, MA 02138 (United States)

2017-09-01

The amplitude of large-scale matter fluctuations inferred from the observed Sunyaev-Zeldovich (SZ) cluster mass function and from weak gravitational lensing studies, when taken at face value, is in tension with measurements of the cosmic microwave background (CMB) and baryon acoustic oscillation (BAO). In this work, we revisit whether this possible discrepancy can be attributed to new interactions in the dark matter sector. Focusing on a cosmological model where dark matter interacts with a dark radiation species until the epoch of matter-radiation equality, we find that measurements of the Lyman-alpha flux power spectrum from the Sloan Digital Sky Survey provide no support to the hypothesis that new dark matter interactions can resolve the possible tension between CMB and large-scale structure (LSS). Indeed, while the addition of dark matter-dark radiation interactions leads to an improvement of 2ΔlnL=12 with respect to the standard Λ cold dark matter (ΛCDM) model when only CMB, BAO, and LSS data are considered, the inclusion of Lyman-alpha data reduces the improvement of the fit to 2ΔlnL=6 relative to ΛCDM . We thus conclude that the statistical evidence for new dark matter interactions (largely driven by the Planck SZ dataset) is marginal at best, and likely caused by systematics in the data. We also perform a Fisher forecast analysis for the reach of a future dataset composed of a CMB-S4 experiment combined with the Large Synoptic Survey Telescope galaxy survey. We find that the constraint on the effective number of fluid-like dark radiation species, Δ N {sub fluid}, will be improved by an order of magnitude compared to current bounds.

The Herschel-ATLAS: magnifications and physical sizes of 500-μm-selected strongly lensed galaxies

Science.gov (United States)

Enia, A.; Negrello, M.; Gurwell, M.; Dye, S.; Rodighiero, G.; Massardi, M.; De Zotti, G.; Franceschini, A.; Cooray, A.; van der Werf, P.; Birkinshaw, M.; Michałowski, M. J.; Oteo, I.

2018-04-01

We perform lens modelling and source reconstruction of Sub-millimetre Array (SMA) data for a sample of 12 strongly lensed galaxies selected at 500μm in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). A previous analysis of the same data set used a single Sérsic profile to model the light distribution of each background galaxy. Here we model the source brightness distribution with an adaptive pixel scale scheme, extended to work in the Fourier visibility space of interferometry. We also present new SMA observations for seven other candidate lensed galaxies from the H-ATLAS sample. Our derived lens model parameters are in general consistent with previous findings. However, our estimated magnification factors, ranging from 3 to 10, are lower. The discrepancies are observed in particular where the reconstructed source hints at the presence of multiple knots of emission. We define an effective radius of the reconstructed sources based on the area in the source plane where emission is detected above 5σ. We also fit the reconstructed source surface brightness with an elliptical Gaussian model. We derive a median value reff ˜ 1.77 kpc and a median Gaussian full width at half-maximum ˜1.47 kpc. After correction for magnification, our sources have intrinsic star formation rates (SFR) ˜ 900-3500 M⊙ yr-1, resulting in a median SFR surface density ΣSFR ˜ 132 M⊙ yr-1 kpc-2 (or ˜218 M⊙ yr-1 kpc-2 for the Gaussian fit). This is consistent with that observed for other star-forming galaxies at similar redshifts, and is significantly below the Eddington limit for a radiation pressure regulated starburst.

Lyman-alpha detector designed for rocket measurements of the direct solar radiation at 121.5 nm

International Nuclear Information System (INIS)

Guineva, V.; Tashev, V.; Witt, G.; Gumbel, J.; Khaplanov, M.

2007-01-01

Rocket measurements of the direct Lyman-alpha radiation penetrating in the atmosphere were planned during the HotPay I rocket experiment, June 2006, Project ASLAF (Attenuation of the Solar Lyman-Alpha Flux), Andoya Rocket Range (ARR), Norway. The basic goal of ASLAF project was the study of the processes in the summer mesosphere and thermosphere (up to 110 km), at high latitudes using the Lyman-alpha measurements. The resonance transition 2 P- 2 S of the atomic hydrogen (Lyman-alpha emission) is the strongest and most conspicuous feature in the solar EUV spectrum. Due to the favourable circumstance, that the Lyman-alpha wavelength (121.5 nm) coincides with a minimum of the O 2 absorption spectrum, the direct Lyman-alpha radiation penetrates well in the mesosphere. The Lyman-alpha radiation is the basic agent of the NO molecules ionization, thus generating the ionospheric D-layer, and of the water vapour photolysis, being one of the main H 2 O loss processes. The Lyman-alpha radiation transfer depends on the resonance scattering from the hydrogen atoms in the atmosphere and on the O 2 absorption. Since the Lyman-alpha extinction in the atmosphere is a measure for the column density of the oxygen molecules, the atmospheric temperature profile can be calculated thereof. The detector of solar Lyman-alpha radiation was manufactured in the Stara Zagora Department of the Solar-Terrestrial Influences Laboratory (STIL). Its basic part is an ionization chamber, filled in with NO. A 60 V power supply is applied to the chamber. The produced photoelectric current from the sensor is fed to a 2-channels amplifier, providing an analogue signal. The characteristics of the Lyman-alpha detector were studied. It passed successfully all tests and the results showed that the instrument could be used in rocket experiments to measure the Lyman-alpha flux. From the measurements of the detector, the Lyman-alpha vertical profile can be obtained. The forthcoming scientific data analysis will

Models of the strongly lensed quasar DES J0408-5354

Science.gov (United States)

Agnello, A.; Lin, H.; Buckley-Geer, L.; Treu, T.; Bonvin, V.; Courbin, F.; Lemon, C.; Morishita, T.; Amara, A.; Auger, M. W.; Birrer, S.; Chan, J.; Collett, T.; More, A.; Fassnacht, C. D.; Frieman, J.; Marshall, P. J.; McMahon, R. G.; Meylan, G.; Suyu, S. H.; Castander, F.; Finley, D.; Howell, A.; Kochanek, C.; Makler, M.; Martini, P.; Morgan, N.; Nord, B.; Ostrovski, F.; Schechter, P.; Tucker, D.; Wechsler, R.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Flaugher, B.; Fosalba, P.; García-Bellido, J.; Gaztanaga, E.; Gill, M. S.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

2017-12-01

We present detailed modelling of the recently discovered, quadruply lensed quasar J0408-5354, with the aim of interpreting its remarkable configuration: besides three quasar images (A,B,D) around the main deflector (G1), a fourth image (C) is significantly reddened and dimmed by a perturber (G2) which is not detected in the Dark Energy Survey imaging data. From lens models incorporating (dust-corrected) flux ratios, we find a perturber Einstein radius 0.04 arcsec ≲ RE, G2 ≲ 0.2 arcsec and enclosed mass Mp(RE, G2) ≲ 1.0 × 1010 M⊙. The main deflector has stellar mass log _{10}(M_{\\star }/M_{⊙})=11.49^{+0.46}_{-0.32}, a projected mass Mp(RE, G1) ≈ 6 × 1011 M⊙ within its Einstein radius RE, G1 = (1.85 ± 0.15) arcsec and predicted velocity dispersion 267-280 km s-1. Follow-up images from a companion monitoring campaign show additional components, including a candidate second source at a redshift between the quasar and G1. Models with free perturbers, and dust-corrected and delay-corrected flux ratios, are also explored. The predicted time-delays (ΔtAB = (135.0 ± 12.6) d, ΔtBD = (21.0 ± 3.5) d) roughly agree with those measured, but better imaging is required for proper modelling and comparison. We also discuss some lessons learnt from J0408-5354 on lensed quasar finding strategies, due to its chromaticity and morphology.

Lyman-continuum leakage as dominant source of diffuse ionized gas in the Antennae galaxy

Science.gov (United States)

Weilbacher, Peter M.; Monreal-Ibero, Ana; Verhamme, Anne; Sandin, Christer; Steinmetz, Matthias; Kollatschny, Wolfram; Krajnović, Davor; Kamann, Sebastian; Roth, Martin M.; Erroz-Ferrer, Santiago; Marino, Raffaella Anna; Maseda, Michael V.; Wendt, Martin; Bacon, Roland; Dreizler, Stefan; Richard, Johan; Wisotzki, Lutz

2018-04-01

The Antennae galaxy (NGC 4038/39) is the closest major interacting galaxy system and is therefore often studied as a merger prototype. We present the first comprehensive integral field spectroscopic dataset of this system, observed with the MUSE instrument at the ESO VLT. We cover the two regions in this system which exhibit recent star formation: the central galaxy interaction and a region near the tip of the southern tidal tail. In these fields, we detect HII regions and diffuse ionized gas to unprecedented depth. About 15% of the ionized gas was undetected by previous observing campaigns. This newly detected faint ionized gas is visible everywhere around the central merger, and shows filamentary structure. We estimate diffuse gas fractions of about 60% in the central field and 10% in the southern region. We are able to show that the southern region contains a significantly different population of HII regions, showing fainter luminosities. By comparing HII region luminosities with the HST catalog of young star clusters in the central field, we estimate that there is enough Lyman-continuum leakage in the merger to explain the amount of diffuse ionized gas that we detect. We compare the Lyman-continuum escape fraction of each HII region against emission line ratios that are sensitive to the ionization parameter. While we find no systematic trend between these properties, the most extreme line ratios seem to be strong indicators of density bounded ionization. Extrapolating the Lyman-continuum escape fractions to the southern region, we conclude that simply from the comparison of the young stellar populations to the ionized gas there is no need to invoke other ionization mechanisms than Lyman-continuum leaking HII regions for the diffuse ionized gas in the Antennae. FITS images and Table of HII regions are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/611/A95 and at http://muse-vlt.eu/science/antennae/

Are the brightest Lyman Alpha Emitters at z=5.7 primeval galaxies?

Science.gov (United States)

Lidman, Christopher; Jones, Heath; Meisenheimer, Klaus; Pompei, Emanuela; Tapken, Christian; Vanzi, Leonardo; Westra, Eduard

2008-03-01

Wide-field, narrow-band surveys have proven to be effective at finding very high redshift galaxies that emit brightly in the Lyman alpha line, the so-called Lyman alpha emitters (LAEs). It was through this technique that the most distant spectroscopically confirmed galaxy, a galaxy at z=6.96, was discovered. Considerable effort is currently being spent on discovering these galaxies at ever higher redshifts by extending this technique into the near-IR. In contrast to this effort, there has been relatively little work on understanding these galaxies. In particular, how do LAEs relate to other high redshift galaxies, such as the galaxies discovered through broad band drop out techniques, and, perhaps, more importantly, what role do LAEs play in re-ionising the universe. We recently discovered two extremely luminous LAEs at z=5.7. These LAEs are among the brightest LAEs ever discovered at this redshift. In a recent paper by Mao et al. the brightest LAEs are associated to the most massive halos. We propose to use the IRAC 3.6 micron imager on Spitzer to measure the rest-frame optical flux of the these LAEs. With additional data from the near-IR (rest-frame UV) and very deep optical spectra around the Lyman alpha line, we propose to make a detailed study of the spectral energy distribution from the Lyman alpha line to the rest frame optical of these exceptional LAEs. These data will enable us to estimate the age and mass of the stellar burst that produces the Lyman alpha line, to estimate the contribution from an older stellar population, if any, and to estimate the fraction of Lyman continuum photons that can escape the galaxy and are thus available to reionise the universe.

Combining strong lensing and dynamics in galaxy clusters: integrating MAMPOSSt within LENSTOOL. I. Application on SL2S J02140-0535

Science.gov (United States)

Verdugo, T.; Limousin, M.; Motta, V.; Mamon, G. A.; Foëx, G.; Gastaldello, F.; Jullo, E.; Biviano, A.; Rojas, K.; Muñoz, R. P.; Cabanac, R.; Magaña, J.; Fernández-Trincado, J. G.; Adame, L.; De Leo, M. A.

2016-10-01

Context. The mass distribution in galaxy clusters and groups is an important cosmological probe. It has become clear in recent years that mass profiles are best recovered when combining complementary probes of the gravitational potential. Strong lensing (SL) is very accurate in the inner regions, but other probes are required to constrain the mass distribution in the outer regions, such as weak lensing or studies of dynamics. Aims: We constrain the mass distribution of a cluster showing gravitational arcs by combining a strong lensing method with a dynamical method using the velocities of its 24 member galaxies. Methods: We present a new framework in which we simultaneously fit SL and dynamical data. The SL analysis is based on the LENSTOOL software and the dynamical analysis uses the MAMPOSSt code, which we integrated into LENSTOOL. After describing the implementation of this new tool, we applied it to the galaxy group SL2S J02140-0535 (zspec = 0.44), which we had previously studied. We used new VLT/FORS2 spectroscopy of multiple images and group members, as well as shallow X-ray data from XMM. Results: We confirm that the observed lensing features in SL2S J02140-0535 belong to different background sources. One of these sources is located at zspec = 1.017 ± 0.001, whereas the other source is located at zspec = 1.628 ± 0.001. With the analysis of our new and our previously reported spectroscopic data, we find 24 secure members for SL2S J02140-0535. Both data sets are well reproduced by a single NFW mass profile; the dark matter halo coincides with the peak of the light distribution, with scale radius, concentration, and mass equal to rs = 82+44-17 kpc, c200 = 10.0+1.7-2.5, and M200 = 1.0+0.5-0.2 × 1014 M⊙ respectively. These parameters are better constrained when we fit SL and dynamical information simultaneously. The mass contours of our best model agrees with the direction defined by the luminosity contours and the X-ray emission of SL2S J02140-0535. The

A reliable cw Lyman-{alpha} laser source for future cooling of antihydrogen

Energy Technology Data Exchange (ETDEWEB)

Kolbe, Daniel, E-mail: kolbed@uni-mainz.de; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen [Johannes Gutenberg-Universitaet, Institut fuer Physik (Germany)

2012-12-15

We demonstrate a reliable continuous-wave (cw) laser source at the 1 S-2 P transition in (anti)hydrogen at 121.56 nm (Lyman-{alpha}) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-{alpha} source and is well investigated.

A reliable cw Lyman-α laser source for future cooling of antihydrogen

International Nuclear Information System (INIS)

Kolbe, Daniel; Beczkowiak, Anna; Diehl, Thomas; Koglbauer, Andreas; Sattler, Matthias; Stappel, Matthias; Steinborn, Ruth; Walz, Jochen

2012-01-01

We demonstrate a reliable continuous-wave (cw) laser source at the 1 S–2 P transition in (anti)hydrogen at 121.56 nm (Lyman-α) based on four-wave sum-frequency mixing in mercury. A two-photon resonance in the four-wave mixing scheme is essential for a powerful cw Lyman-α source and is well investigated.

Achromatic X-ray lenses

International Nuclear Information System (INIS)

Umbach, Marion

2009-01-01

This thesis presents first results on the development of achromatic refractive X-ray lenses which can be used for scientific experiments at synchrotron sources. First of all the different requirements for achromatic X-ray lenses have been worked out. There are different types of lenses, one type can be used for monochromatized sources when the energy is scanned while the spot size should be constant. The other type can be used at beamlines providing a broad energy band. By a combination of focusing and defocusing elements we have developed a lens system that strongly reduces the chromatic aberration of a refractive lens in a given energy range. The great challenge in the X-ray case - in contrast to the visible range - the complex refractive index, which is very similar for the possible materials in the X-ray spectrum. For precise studies a numerical code has been developed, which calculates the different rays on their way through the lenses to the detector plane via raytracing. In this numerical code the intensity distribution in the detector plane has been analyzed for a chromatic and the corresponding achromatic system. By optimization routines for the two different fields of applications specific parameter combinations were found. For the experimental verification an achromatic system has been developed, consisting of biconcave SU-8 lenses and biconvex Nickel Fresnel lenses. Their fabrication was based on the LIGA-process, including a further innovative development, namely the fabrication of two different materials on one wafer. In the experiment at the synchrotron source ANKA the energy was varied in a specific energy range in steps of 0.1 keV. The intensity distribution for the different energies was detected at a certain focal length. For the achromatic system a reduction of the chromatic aberration could be clearly shown. Achromatic refractive X-ray lenses, especially for the use at synchrotron sources, have not been developed so far. As a consequence of the

Direct method gas-phase oxygen abundances of four Lyman break analogs

Energy Technology Data Exchange (ETDEWEB)

Brown, Jonathan S.; Croxall, Kevin V.; Pogge, Richard W. [Department of Astronomy, The Ohio State University, Columbus, OH 43201 (United States)

2014-09-10

We measure the gas-phase oxygen abundances in four Lyman break analogs using auroral emission lines to derive direct abundances. The direct method oxygen abundances of these objects are generally consistent with the empirically derived strong-line method values, confirming that these objects are low oxygen abundance outliers from the mass-metallicity (MZ) relation defined by star forming Sloan Digital Sky Survey galaxies. We find slightly anomalous excitation conditions (Wolf-Rayet features) that could potentially bias the empirical estimates toward high values if caution is not exercised in the selection of the strong-line calibration. The high rate of star formation and low oxygen abundance of these objects is consistent with the predictions of the fundamental metallicity relation, in which the infall of relatively unenriched gas simultaneously triggers an episode of star formation and dilutes the interstellar medium of the host galaxy.

DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

Energy Technology Data Exchange (ETDEWEB)

Agnello, A.; et al.

2017-11-10

We report the discovery, spectroscopic confirmation and first lens models of the first two, strongly lensed quasars from a combined search in WISE and Gaia over the DES footprint. The four-image lensWGD2038-4008 (r.a.=20:38:02.65, dec.=-40:08:14.64) has source- and lens-redshifts $z_{s}=0.777 \\pm 0.001$ and $z_l = 0.230 \\pm 0.002$ respectively. Its deflector has effective radius $R_{\\rm eff} \\approx 3.4^{\\prime\\prime}$, stellar mass $\\log(M_{\\star}/M_{\\odot}) = 11.64^{+0.20}_{-0.43}$, and shows extended isophotal shape variation. Simple lens models yield Einstein radii $R_{\\rm E}=(1.30\\pm0.04)^{\\prime\\prime},$ axis ratio $q=0.75\\pm0.1$ (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lensWGD2021-4115 (r.a.=20:21:39.45, dec.=--41:15:57.11) has $z_{s}=1.390\\pm0.001$ and $z_l = 0.335 \\pm 0.002$, and Einstein radius $R_{\\rm E} = (1.1\\pm0.1)^{\\prime\\prime},$ but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. We also show high-rank candidate doubles selected this way, some of which have been independently identified with different techniques, and discuss a DES+WISE quasar multiplet selection.

Prescribing prophylactic antibiotics to users of therapeutic contact lenses.

Science.gov (United States)

Colomé-Campos, J; Quevedo-Junyent, L; Godoy-Barreda, N; Martínez-Salcedo, I; Romero-Aroca, P

2013-03-01

To describe the benefits and optimum use of prophylactic antibiotics in users of therapeutic contact lenses (TCL). A microbiological study was carried out on samples from 33 patients who continuously wore TCL. The resistance to antibiotics of bacteria isolated in our health region was also reviewed. An assessment was also made on whether there were microorganisms of a higher pathogenic potential in TCL than conventional contact lenses, as reported in the literature. No bacteria were isolated from 17 (52%) of the 33 lenses studied. From the 16 (48%) remaining lenses, coagulase negative Staphylococci were isolated from 10 (62%), Propionibacterium acnes from 4 (25%), and Corynebacterium from 2 (13%). The high number of negative cultures and the presence of saprophytic bacteria indicate that prophylactic antibiotic treatment is not precise. The most frequent pathogenic bacteria found in contact lenses are strongly resistant to the current commercially available antibiotics. Copyright © 2012 Sociedad Española de Oftalmología. Published by Elsevier Espana. All rights reserved.

THE EFFECT OF ENVIRONMENT ON SHEAR IN STRONG GRAVITATIONAL LENSES

International Nuclear Information System (INIS)

Wong, Kenneth C.; Zabludoff, Ann I.; Keeton, Charles R.; Williams, Kurtis A.; Momcheva, Ivelina G.

2011-01-01

Using new photometric and spectroscopic data in the fields of nine strong gravitational lenses that lie in galaxy groups, we analyze the effects of both the local group environment and line-of-sight (LOS) galaxies on the lens potential. We use Monte Carlo simulations to derive the shear directly from measurements of the complex lens environment, providing the first detailed independent check of the shear obtained from lens modeling. We account for possible tidal stripping of the group galaxies by varying the fraction of total mass apportioned between the group dark matter halo and individual group galaxies. The environment produces an average shear of γ = 0.08 (ranging from 0.02 to 0.17), significant enough to affect quantities derived from lens observables. However, the direction and magnitude of the shears do not match those obtained from lens modeling in three of the six four-image systems in our sample (B1422, RXJ1131, and WFI2033). The source of this disagreement is not clear, implying that the assumptions inherent in both the environment and lens model approaches must be reconsidered. If only the local group environment of the lens is included, the average shear is γ = 0.05 (ranging from 0.01 to 0.14), indicating that LOS contributions to the lens potential are not negligible. We isolate the effects of various theoretical and observational uncertainties on our results. Of those uncertainties, the scatter in the Faber-Jackson relation and error in the group centroid position dominate. Future surveys of lens environments should prioritize spectroscopic sampling of both the local lens environment and objects along the LOS, particularly those bright (I< 21.5) galaxies projected within 5' of the lens.

CLASH: DISCOVERY OF A BRIGHT z {approx_equal} 6.2 DWARF GALAXY QUADRUPLY LENSED BY MACS J0329.6-0211

Energy Technology Data Exchange (ETDEWEB)

Zitrin, A. [Institut fuer Theoretische Astrophysik, Universitaet Heidelberg, Heidelberg (Germany); Moustakas, J. [Center for Astrophysics and Space Sciences, University of California, San Diego, CA (United States); Bradley, L.; Coe, D.; Postman, M.; Koekemoer, A. [Space Telescope Science Institute, Baltimore, MD (United States); Moustakas, L. A. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States); Shu, X. [Department of Astronomy, University of Science and Technology of China, Hefei, Anhui (China); Zheng, W.; Ford, H. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD (United States); Benitez, N. [Instituto de Astrofisica de Andalucia (CSIC), Granada (Spain); Bouwens, R. [Leiden Observatory, University of Leiden, Leiden (Netherlands); Broadhurst, T. [Department of Theoretical Physics, University of Basque Country, Bilbao (Spain); Host, O.; Jouvel, S. [Department of Physics and Astronomy, University College London, London (United Kingdom); Meneghetti, M. [INAF, Osservatorio Astronomico di Bologna, Bologna (Italy); Rosati, P. [European Southern Observatory, Garching bei Muenchen (Germany); Donahue, M. [Physics and Astronomy Department, Michigan State University, East Lansing, MI (United States); Grillo, C. [Excellence Cluster Universe, Technische Universitaet Muenchen, Muenchen (Germany); Kelson, D., E-mail: adizitrin@gmail.com [Observatories of the Carnegie Institution of Washington, Pasadena, CA (United States); and others

2012-03-15

We report the discovery of a z{sub phot} = 6.18{sup +0.05}{sub -0.07} (95% confidence level) dwarf galaxy, lensed into four images by the galaxy cluster MACS J0329.6-0211 (z{sub l} = 0.45). The galaxy is observed as a high-redshift dropout in HST/ACS/WFC3 CLASH and Spitzer/IRAC imaging. Its redshift is securely determined due to a clear detection of the Lyman break in the 18-band photometry, making this galaxy one of the highest-redshift multiply lensed objects known to date with an observed magnitude of F125W =24.00 {+-} 0.04 AB mag for its most magnified image. We also present the first strong-lensing analysis of this cluster uncovering 15 additional multiply imaged candidates of five lower-redshift sources spanning the range z{sub s} {approx_equal} 2-4. The mass model independently supports the high photometric redshift and reveals magnifications of 11.6{sup +8.9}{sub -4.1}, 17.6{sup +6.2}{sub -3.9}, 3.9{sup +3.0}{sub -1.7}, and 3.7{sup +1.3}{sub -0.2}, respectively, for the four images of the high-redshift galaxy. By delensing the most magnified image we construct an image of the source with a physical resolution of {approx}200 pc when the universe was {approx}0.9 Gyr old, where the z {approx_equal} 6.2 galaxy occupies a source-plane area of approximately 2.2 kpc{sup 2}. Modeling the observed spectral energy distribution using population synthesis models, we find a demagnified stellar mass of {approx}10{sup 9} M{sub Sun }, subsolar metallicity (Z/Z{sub Sun} {approx} 0.5), low dust content (A{sub V} {approx} 0.1 mag), a demagnified star formation rate (SFR) of {approx}3.2 M{sub Sun} yr{sup -1}, and a specific SFR of {approx}3.4 Gyr{sup -1}, all consistent with the properties of local dwarf galaxies.

Development of a Lyman-α Imaging Solar Telescope for the Satellite

Directory of Open Access Journals (Sweden)

M. Jang

2005-09-01

Full Text Available Long term observations of full-disk Lyman-α irradiance have been made by the instruments on various satellites. In addition, several sounding rockets dating back to the 1950s and up through the present have measured the Lyman-α irradiance. Previous full disk Lyman-α images of the sun have been very interesting and useful scientifically, but have been only five-minute ``snapshots" obtained on sounding rocket flights. All of these observations to date have been snapshots, with no time resolution to observe changes in the chromospheric structure as a result of the evolving magnetic field, and its effect on the Lyman-α intensity. The Lyman-α Imaging Solar Telescope(LIST can provide a unique opportunity for the study of the sun in the Lyman-α region with the high time and spatial resolution for the first time. Up to the 2nd year development, the preliminary design of the optics, mechanical structure and electronics system has been completed. Also the mechanical structure analysis, thermal analysis were performed and the material for the structure was chosen as a result of these analyses. And the test plan and the verification matrix were decided. The operation systems, technical and scientific operation, were studied and finally decided. Those are the technical operation, mechanical working modes for the observation and safety, the scientific operation and the process of the acquired data. The basic techniques acquired through the development of satellite based solar telescope are essential for the construction of space environment forecast system in the future. The techniques which we developed through this study, like mechanical, optical and data processing techniques, could be applied extensively not only to the process of the future production of flight models of this kind, but also to the related industries. Also, we can utilize the scientific achievements which are obtained throughout the project. And these can be utilized to build a high

LENSING NOISE IN MILLIMETER-WAVE GALAXY CLUSTER SURVEYS

International Nuclear Information System (INIS)

Hezaveh, Yashar; Vanderlinde, Keith; Holder, Gilbert; De Haan, Tijmen

2013-01-01

We study the effects of gravitational lensing by galaxy clusters of the background of dusty star-forming galaxies (DSFGs) and the cosmic microwave background (CMB), and examine the implications for Sunyaev-Zel'dovich-based (SZ) galaxy cluster surveys. At the locations of galaxy clusters, gravitational lensing modifies the probability distribution of the background flux of the DSFGs as well as the CMB. We find that, in the case of a single-frequency 150 GHz survey, lensing of DSFGs leads both to a slight increase (∼10%) in detected cluster number counts (due to a ∼50% increase in the variance of the DSFG background, and hence an increased Eddington bias) and a rare (occurring in ∼2% of clusters) 'filling-in' of SZ cluster signals by bright strongly lensed background sources. Lensing of the CMB leads to a ∼55% reduction in CMB power at the location of massive galaxy clusters in a spatially matched single-frequency filter, leading to a net decrease in detected cluster number counts. We find that the increase in DSFG power and decrease in CMB power due to lensing at cluster locations largely cancel, such that the net effect on cluster number counts for current SZ surveys is subdominant to Poisson errors

Beryllium parabolic refractive x-ray lenses

International Nuclear Information System (INIS)

Lengeler, B.; Schroer, C.G.; Kuhlmann, M.; Benner, B.; Guenzler, T.F.; Kurapova, O.; Somogyi, A.; Snigirev, A.; Snigireva, I.

2004-01-01

Parabolic refractive x-ray lenses are novel optical components for the hard x-ray range from about 5 keV to about 120 keV. They focus in both directions. They are compact, robust, and easy to align and to operate. They can be used like glass lenses are used for visible light, the main difference being that the numerical aperture N.A. is much smaller than 1 (of order 10-4 to 10-3). Their main applications are in micro- and nanofocusing, in imaging by absorption and phase contrast and in fluorescence mode. In combination with tomography they allow for 3-dimensional imaging of opaque media with submicrometer resolution. Finally, they can be used in speckle spectroscopy by means of coherent x-ray scattering. Beryllium as lens material strongly enhances the transmission and the field of view as compared to aluminium. With increased N.A. the lateral resolution is also considerably improved with Be lenses. References to a number of applications are given

FAST VARIABILITY AND MILLIMETER/IR FLARES IN GRMHD MODELS OF Sgr A* FROM STRONG-FIELD GRAVITATIONAL LENSING

Energy Technology Data Exchange (ETDEWEB)

Chan, Chi-kwan; Psaltis, Dimitrios; Özel, Feryal; Marrone, Daniel [Steward Observatory and Department of Astronomy, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States); Medeiros, Lia [Department of Physics, Broida Hall, University of California, Santa Barbara, Santa Barbara, CA 93106 (United States); Sadowski, Aleksander [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Narayan, Ramesh, E-mail: chanc@email.arizona.edu [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2015-10-20

We explore the variability properties of long, high-cadence general relativistic magnetohydrodynamic (GRMHD) simulations across the electromagnetic spectrum using an efficient, GPU-based radiative transfer algorithm. We focus on both standard and normal evolution (SANE) and magnetically arrested disk (MAD) simulations with parameters that successfully reproduce the time-averaged spectral properties of Sgr A* and the size of its image at 1.3 mm. We find that the SANE models produce short-timescale variability with amplitudes and power spectra that closely resemble those inferred observationally. In contrast, MAD models generate only slow variability at lower flux levels. Neither set of models shows any X-ray flares, which most likely indicates that additional physics, such as particle acceleration mechanisms, need to be incorporated into the GRMHD simulations to account for them. The SANE models show strong, short-lived millimeter/infrared (IR) flares, with short (≲1 hr) time lags between the millimeter and IR wavelengths, that arise from the combination of short-lived magnetic flux tubes and strong-field gravitational lensing near the horizon. Such events provide a natural explanation for the observed IR flares with no X-ray counterparts.

Gravitational lensing of gravitational waves: a statistical perspective

Science.gov (United States)

Li, Shun-Sheng; Mao, Shude; Zhao, Yuetong; Lu, Youjun

2018-05-01

In this paper, we study the strong gravitational lensing of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar binary black hole coalescences. These are most promising targets for ground-based detectors such as Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO) and the proposed Einstein Telescope (ET) and can be safely treated under the geometrical optics limit for GW propagation. We perform a thorough calculation of the lensing rate, by taking account of effects caused by the ellipticity of lensing galaxies, lens environments, and magnification bias. We find that in certain GW source rate scenarios, we should be able to observe strongly lensed GW events once per year (˜1 yr-1) in the aLIGO survey at its design sensitivity; for the proposed ET survey, the rate could be as high as ˜80 yr-1. These results depend on the estimate of GW source abundance, and hence can be correspondingly modified with an improvement in our understanding of the merger rate of stellar binary black holes. We also compute the fraction of four-image lens systems in each survey, predicting it to be ˜30 per cent for the aLIGO survey and ˜6 per cent for the ET survey. Finally, we evaluate the possibility of missing some images due to the finite survey duration, by presenting the probability distribution of lensing time delays. We predict that this selection bias will be insignificant in future GW surveys, as most of the lens systems ({˜ } 90{per cent}) will have time delays less than ˜1 month, which will be far shorter than survey durations.

ALMA observations of lensed Herschel sources: testing the dark matter halo paradigm

Science.gov (United States)

Amvrosiadis, A.; Eales, S. A.; Negrello, M.; Marchetti, L.; Smith, M. W. L.; Bourne, N.; Clements, D. L.; De Zotti, G.; Dunne, L.; Dye, S.; Furlanetto, C.; Ivison, R. J.; Maddox, S. J.; Valiante, E.; Baes, M.; Baker, A. J.; Cooray, A.; Crawford, S. M.; Frayer, D.; Harris, A.; Michałowski, M. J.; Nayyeri, H.; Oliver, S.; Riechers, D. A.; Serjeant, S.; Vaccari, M.

2018-04-01

With the advent of wide-area submillimetre surveys, a large number of high-redshift gravitationally lensed dusty star-forming galaxies have been revealed. Because of the simplicity of the selection criteria for candidate lensed sources in such surveys, identified as those with S500 μm > 100 mJy, uncertainties associated with the modelling of the selection function are expunged. The combination of these attributes makes submillimetre surveys ideal for the study of strong lens statistics. We carried out a pilot study of the lensing statistics of submillimetre-selected sources by making observations with the Atacama Large Millimeter Array (ALMA) of a sample of strongly lensed sources selected from surveys carried out with the Herschel Space Observatory. We attempted to reproduce the distribution of image separations for the lensed sources using a halo mass function taken from a numerical simulation that contains both dark matter and baryons. We used three different density distributions, one based on analytical fits to the haloes formed in the EAGLE simulation and two density distributions [Singular Isothermal Sphere (SIS) and SISSA] that have been used before in lensing studies. We found that we could reproduce the observed distribution with all three density distributions, as long as we imposed an upper mass transition of ˜1013 M⊙ for the SIS and SISSA models, above which we assumed that the density distribution could be represented by a Navarro-Frenk-White profile. We show that we would need a sample of ˜500 lensed sources to distinguish between the density distributions, which is practical given the predicted number of lensed sources in the Herschel surveys.

Mesh-free free-form lensing - I. Methodology and application to mass reconstruction

Science.gov (United States)

Merten, Julian

2016-09-01

Many applications and algorithms in the field of gravitational lensing make use of meshes with a finite number of nodes to analyse and manipulate data. Specific examples in lensing are astronomical CCD images in general, the reconstruction of density distributions from lensing data, lens-source plane mapping or the characterization and interpolation of a point spread function. We present a numerical framework to interpolate and differentiate in the mesh-free domain, defined by nodes with coordinates that follow no regular pattern. The framework is based on radial basis functions (RBFs) to smoothly represent data around the nodes. We demonstrate the performance of Gaussian RBF-based, mesh-free interpolation and differentiation, which reaches the sub-percent level in both cases. We use our newly developed framework to translate ideas of free-form mass reconstruction from lensing on to the mesh-free domain. By reconstructing a simulated mock lens we find that strong-lensing only reconstructions achieve <10 per cent accuracy in the areas where these constraints are available but provide poorer results when departing from these regions. Weak-lensing only reconstructions give <10 per cent accuracy outside the strong-lensing regime, but cannot resolve the inner core structure of the lens. Once both regimes are combined, accurate reconstructions can be achieved over the full field of view. The reconstruction of a simulated lens, using constraints that mimics real observations, yields accurate results in terms of surface-mass density, Navarro-Frenk-White profile (NFW) parameters, Einstein radius and magnification map recovery, encouraging the application of this method to real data.

A new strong-lensing galaxy at z=0.066: Another elliptical galaxy with a lightweight IMF

Science.gov (United States)

Collier, William P.; Smith, Russell J.; Lucey, John R.

2018-05-01

We report the discovery of a new low-redshift galaxy-scale gravitational lens, identified from a systematic search of publicly available MUSE observations. The lens galaxy, 2MASXJ04035024-0239275, is a giant elliptical at z = 0.06604 with a velocity dispersion of σ = 314 km s-1. The lensed source has a redshift of 0.19165 and forms a pair of bright images on either side of the lens centre. The Einstein radius is 1.5 arcsec, projecting to 1.8 kpc, which is just one quarter of the galaxy effective radius. After correcting for an estimated 19 per cent dark matter contribution, we find that the stellar mass-to-light ratio from lensing is consistent with that expected for a Milky Way initial mass function (IMF). Combining the new system with three previously-studied low-redshift lenses of similar σ, the derived mean mass excess factor (relative to a Kroupa IMF) is ⟨α⟩ = 1.09±0.08. With all four systems, the intrinsic scatter in α for massive elliptical galaxies can be limited to <0.32, at 90 per cent confidence.

Gravitationally Lensed Quasars in Gaia: II. Discovery of 24 Lensed Quasars

Science.gov (United States)

Lemon, Cameron A.; Auger, Matthew W.; McMahon, Richard G.; Ostrovski, Fernanda

2018-04-01

We report the discovery, spectroscopic confirmation and preliminary characterisation of 24 gravitationally lensed quasars identified using Gaia observations. Candidates were selected in the Pan-STARRS footprint with quasar-like WISE colours or as photometric quasars from SDSS, requiring either multiple detections in Gaia or a single Gaia detection near a morphological galaxy. The Pan-STARRS grizY images were modelled for the most promising candidates and 60 candidate systems were followed up with the William Herschel Telescope. 13 of the lenses were discovered as Gaia multiples and 10 as single Gaia detections near galaxies. We also discover 1 lens identified through a quasar emission line in an SDSS galaxy spectrum. The lenses have median image separation 2.13″ and the source redshifts range from 1.06 to 3.36. 4 systems are quadruply-imaged and 20 are doubly-imaged. Deep CFHT data reveal an Einstein ring in one double system. We also report 12 quasar pairs, 10 of which have components at the same redshift and require further follow-up to rule out the lensing hypothesis. We compare the properties of these lenses and other known lenses recovered by our search method to a complete sample of simulated lenses to show the lenses we are missing are mainly those with small separations and higher source redshifts. The initial Gaia data release only catalogues all images of ˜ 30% of known bright lensed quasars, however the improved completeness of Gaia data release 2 will help find all bright lensed quasars on the sky.

Lyman alpha emission in nearby star-forming galaxies with the lowest metallicities and the highest [OIII]/[OII] ratios

Science.gov (United States)

Izotov, Yuri

2017-08-01

The Lyman alpha line of hydrogen is the strongest emission line in galaxies and the tool of predilection for identifying and studying star-forming galaxies over a wide range of redshifts, especially in the early universe. However, it has become clear over the years that not all of the Lyman alpha radiation escapes, due to its resonant scattering on the interstellar and intergalactic medium, and absorption by dust. Although our knowledge of the high-z universe depends crucially on that line, we still do not have a complete understanding of the mechanisms behind the production, radiative transfer and escape of Lyman alpha in galaxies. We wish here to investigate these mechanisms by studying the properties of the ISM in a unique sample of 8 extreme star-forming galaxies (SFGs) that have the highest excitation in the SDSS spectral data base. These dwarf SFGs have considerably lower stellar masses and metallicities, and higher equivalent widths and [OIII]5007/[OII]3727 ratios compared to all nearby SFGs with Lyman alpha emission studied so far with COS. They are, however, very similar to the dwarf Lyman alpha emitters at redshifts 3-6, which are thought to be the main sources of reionization in the early Universe. By combining the HST/COS UV data with data in the optical range, and using photoionization and radiative transfer codes, we will be able to study the properties of the Lyman alpha in these unique objects, derive column densities of the neutral hydrogen N(HI) and compare them with N(HI) obtained from the HeI emission-line ratios in the optical spectra. We will derive Lyman alpha escape fractions and indirectly Lyman continuum escape fractions.

Modeling fine-scale geological heterogeneity-examples of sand lenses in tills

DEFF Research Database (Denmark)

Kessler, Timo Christian; Comunian, Alessandro; Oriani, Fabio

2013-01-01

that hamper subsequent simulation. Transition probability (TP) and multiple-point statistics (MPS) were employed to simulate sand lens heterogeneity. We used one cross-section to parameterize the spatial correlation and a second, parallel section as a reference: it allowed testing the quality......Sand lenses at various spatial scales are recognized to add heterogeneity to glacial sediments. They have high hydraulic conductivities relative to the surrounding till matrix and may affect the advective transport of water and contaminants in clayey till settings. Sand lenses were investigated...... on till outcrops producing binary images of geological cross-sections capturing the size, shape and distribution of individual features. Sand lenses occur as elongated, anisotropic geobodies that vary in size and extent. Besides, sand lenses show strong non-stationary patterns on section images...

Strong bimodality in the host halo mass of central galaxies from galaxy-galaxy lensing

Science.gov (United States)

Mandelbaum, Rachel; Wang, Wenting; Zu, Ying; White, Simon; Henriques, Bruno; More, Surhud

2016-04-01

We use galaxy-galaxy lensing to study the dark matter haloes surrounding a sample of locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey. We measure mean halo mass as a function of the stellar mass and colour of the central galaxy. Mock catalogues constructed from semi-analytic galaxy formation simulations demonstrate that most LBGs are the central objects of their haloes, greatly reducing interpretation uncertainties due to satellite contributions to the lensing signal. Over the full stellar mass range, 10.3 10.7. Tests using the mock catalogues and on the data themselves clarify the effects of LBG selection and show that it cannot artificially induce a systematic dependence of halo mass on LBG colour. The bimodality in halo mass at fixed stellar mass is reproduced by the astrophysical model underlying our mock catalogue, but the sign of the effect is inconsistent with recent, nearly parameter-free age-matching models. The sign and magnitude of the effect can, however, be reproduced by halo occupation distribution models with a simple (few-parameter) prescription for type dependence.

Oxygen sensitivity of krypton and Lyman-alpha hygrometers

NARCIS (Netherlands)

Dijk, van A.; Kohsiek, W.; Bruin, de H.A.R.

2003-01-01

The oxygen sensitivity of krypton and Lyman-¿ hygrometers is studied. Using a dewpoint generator and a controlled nitrogen/oxygen flow the extinction coefficients of five hygrometers associated with the third-order Taylor expansion of the Lambert¿Beer law around reference conditions for oxygen and

CMU DeepLens: deep learning for automatic image-based galaxy-galaxy strong lens finding

Science.gov (United States)

Lanusse, François; Ma, Quanbin; Li, Nan; Collett, Thomas E.; Li, Chun-Liang; Ravanbakhsh, Siamak; Mandelbaum, Rachel; Póczos, Barnabás

2018-01-01

Galaxy-scale strong gravitational lensing can not only provide a valuable probe of the dark matter distribution of massive galaxies, but also provide valuable cosmological constraints, either by studying the population of strong lenses or by measuring time delays in lensed quasars. Due to the rarity of galaxy-scale strongly lensed systems, fast and reliable automated lens finding methods will be essential in the era of large surveys such as Large Synoptic Survey Telescope, Euclid and Wide-Field Infrared Survey Telescope. To tackle this challenge, we introduce CMU DeepLens, a new fully automated galaxy-galaxy lens finding method based on deep learning. This supervised machine learning approach does not require any tuning after the training step which only requires realistic image simulations of strongly lensed systems. We train and validate our model on a set of 20 000 LSST-like mock observations including a range of lensed systems of various sizes and signal-to-noise ratios (S/N). We find on our simulated data set that for a rejection rate of non-lenses of 99 per cent, a completeness of 90 per cent can be achieved for lenses with Einstein radii larger than 1.4 arcsec and S/N larger than 20 on individual g-band LSST exposures. Finally, we emphasize the importance of realistically complex simulations for training such machine learning methods by demonstrating that the performance of models of significantly different complexities cannot be distinguished on simpler simulations. We make our code publicly available at https://github.com/McWilliamsCenter/CMUDeepLens.

MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO

Science.gov (United States)

Griffiths, Alex; Conselice, Christopher J.; Alpaslan, Mehmet; Frye, Brenda L.; Diego, Jose M.; Zitrin, Adi; Yan, Haojing; Ma, Zhiyuan; Barone-Nugent, Robert; Bhatawdekar, Rachana; Driver, Simon P.; Robotham, Aaron S. G.; Windhorst, Rogier A.; Wyithe, J. Stuart B.

2018-04-01

We present the results of a VLT MUSE/FORS2 and Spitzer survey of a unique compact lensing cluster CLIO at z = 0.42, discovered through the GAMA survey using spectroscopic redshifts. Compact and massive clusters such as this are understudied, but provide a unique prospective on dark matter distributions and for finding background lensed high-z galaxies. The CLIO cluster was identified for follow-up observations due to its almost unique combination of high-mass and dark matter halo concentration, as well as having observed lensing arcs from ground-based images. Using dual band optical and infra-red imaging from FORS2 and Spitzer, in combination with MUSE optical spectroscopy we identify 89 cluster members and find background sources out to z = 6.49. We describe the physical state of this cluster, finding a strong correlation between environment and galaxy spectral type. Under the assumption of an NFW profile, we measure the total mass of CLIO to be M200 = (4.49 ± 0.25) × 1014 M⊙. We build and present an initial strong-lensing model for this cluster, and measure a relatively low intracluster light (ICL) fraction of 7.21 ± 1.53 per cent through galaxy profile fitting. Due to its strong potential for lensing background galaxies and its low ICL, the CLIO cluster will be a target for our 110 h James Webb Space Telescope `Webb Medium-Deep Field' (WMDF) GTO program.

IMPROVED CONSTRAINTS ON THE GRAVITATIONAL LENS Q0957+561. I. WEAK LENSING

International Nuclear Information System (INIS)

Nakajima, R.; Bernstein, G. M.; Fadely, R.; Keeton, C. R.; Schrabback, T.

2009-01-01

Attempts to constrain the Hubble constant using the strong gravitational lens system Q0957+561 are limited by systematic uncertainties in the mass model, since the time delay is known very precisely. One important systematic effect is the mass-sheet degeneracy, which arises because strong lens modeling cannot constrain the presence or absence of a uniform mass sheet κ, which rescales H 0 by the factor (1 - κ). In this paper, we present new constraints on the mass sheet derived from a weak-lensing analysis of the Hubble Space Telescope imaging of a 6 arcmin square region surrounding the lensed quasar. The average mass sheet within a circular aperture (the strong lens model region) is constrained by integrating the tangential weak gravitational shear over the surrounding area. We find the average convergence within a 30'' radius around the lens galaxy to be κ(<30'') = 0.166 ± 0.056 (1σ confidence level), normalized to the quasar redshift. This includes contributions from both the lens galaxy and the surrounding cluster. We also constrain a few other low-order terms in the lens potential by applying a multipole aperture mass formalism to the gravitational shear in an annulus around the strong-lensing region. Implications for strong lens models and the Hubble constant are discussed in an accompanying paper.

The effect of weak lensing on distance estimates from supernovae

Energy Technology Data Exchange (ETDEWEB)

Smith, Mathew; Maartens, Roy [Department of Physics, University of the Western Cape, Cape Town 7535 (South Africa); Bacon, David J.; Nichol, Robert C.; Campbell, Heather; D' Andrea, Chris B. [Institute of Cosmology and Gravitation, University of Portsmouth, Portsmouth, PO1 3FX (United Kingdom); Clarkson, Chris [Astrophysics, Cosmology and Gravity Centre (ACGC), Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch 7701 (South Africa); Bassett, Bruce A. [South African Astronomical Observatory, P.O. Box 9, Observatory 7935 (South Africa); Cinabro, David [Wayne State University, Department of Physics and Astronomy, Detroit, MI 48202 (United States); Finley, David A.; Frieman, Joshua A. [Center for Particle Astrophysics, Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510 (United States); Galbany, Lluis [CENTRA Centro Multidisciplinar de Astrofísica, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisbon (Portugal); Garnavich, Peter M. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Olmstead, Matthew D. [Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112 (United States); Schneider, Donald P. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Shapiro, Charles [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, La Canada Flintridge, CA 91109 (United States); Sollerman, Jesper, E-mail: matsmith2@gmail.com [The Oskar Klein Centre, Department of Astronomy, AlbaNova, SE-106 91 Stockholm (Sweden)

2014-01-01

Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys, combined with a sample of foreground galaxies from SDSS-II, we estimate the weak lensing convergence for each supernova line of sight. We find that the correlation between this measurement and the Hubble residuals is consistent with the prediction from lensing (at a significance of 1.7σ). Strong correlations are also found between the residuals and supernova nuisance parameters after a linear correction is applied. When these other correlations are taken into account, the lensing signal is detected at 1.4σ. We show, for the first time, that distance estimates from supernovae can be improved when lensing is incorporated, by including a new parameter in the SALT2 methodology for determining distance moduli. The recovered value of the new parameter is consistent with the lensing prediction. Using cosmic microwave background data from WMAP7, H {sub 0} data from Hubble Space Telescope and Sloan Digital Sky Survey (SDSS) Baryon acoustic oscillations measurements, we find the best-fit value of the new lensing parameter and show that the central values and uncertainties on Ω {sub m} and w are unaffected. The lensing of supernovae, while only seen at marginal significance in this low-redshift sample, will be of vital importance for the next generation of surveys, such as DES and LSST, which will be systematics-dominated.

New results on strong-interaction effects in antiprotonic hydrogen

International Nuclear Information System (INIS)

Anagnostopoulos, D. F.; Augsburger, M.; Borchert, G.; Castelli, C.; Chatellard, D.; El-Khoury, P.; Egger, J.-P.; Gorke, H.; Gotta, D.; Hauser, P.; Indelicato, P.; Kirch, K.; Lenz, S.; Nelms, N.; Rashid, K.; Schult, O. W. B.; Siems, Th.; Simons, L. M.

1999-01-01

Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the Low-Energy Antiproton Ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using Charge-Coupled Devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction

[O III] EMISSION AND GAS KINEMATICS IN A LYMAN-ALPHA BLOB AT z {approx} 3.1

Energy Technology Data Exchange (ETDEWEB)

McLinden, Emily M. [McDonald Observatory, University of Texas at Austin, Austin, TX 78712 (United States); Malhotra, Sangeeta; Rhoads, James E. [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Hibon, Pascale [Gemini Observatory, La Serena (Chile); Weijmans, Anne-Marie [Dunlap Institute for Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada); Tilvi, Vithal [George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States)

2013-04-10

We present spectroscopic measurements of the [O III] emission line from two subregions of strong Ly{alpha} emission in a radio-quiet Lyman-alpha blob (LAB). The blob under study is LAB1 at z {approx} 3.1, and the [O III] detections are from the two Lyman break galaxies (LBGs) embedded in the blob halo. The [O III] measurements were made with LUCIFER on the 8.4 m Large Binocular Telescope and NIRSPEC on 10 m Keck Telescope. Comparing the redshift of the [O III] measurements to Ly{alpha} redshifts from SAURON allows us to take a step toward understanding the kinematics of the gas in the blob. Using both LUCIFER and NIRSPEC we find velocity offsets between the [O III] and Ly{alpha} redshifts that are modestly negative or consistent with 0 km s{sup -1} in both subregions studied (ranging from -72 {+-} 42- + 6 {+-} 33 km s{sup -1}). A negative offset means Ly{alpha} is blueshifted with respect to [O III] a positive offset then implies Ly{alpha} is redshifted with respect to [O III]. These results may imply that outflows are not primarily responsible for Lyman alpha escape in this LAB, since outflows are generally expected to produce a positive velocity offset. In addition, we present an [O III] line flux upper limit on a third region of LAB1, a region that is unassociated with any underlying galaxy. We find that the [O III] upper limit from the galaxy-unassociated region of the blob is at least 1.4-2.5 times fainter than the [O III] flux from one of the LBG-associated regions and has an [O III] to Ly{alpha} ratio measured at least 1.9-3.4 times smaller than the same ratio measured from one of the LBGs.

Detections of Planets in Binaries Through the Channel of Chang–Refsdal Gravitational Lensing Events

Energy Technology Data Exchange (ETDEWEB)

Han, Cheongho [Department of Physics, Chungbuk National University, Cheongju 361-763 (Korea, Republic of); Shin, In-Gu; Jung, Youn Kil [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

2017-02-01

Chang–Refsdal (C–R) lensing, which refers to the gravitational lensing of a point mass perturbed by a constant external shear, provides a good approximation in describing lensing behaviors of either a very wide or a very close binary lens. C–R lensing events, which are identified by short-term anomalies near the peak of high-magnification lensing light curves, are routinely detected from lensing surveys, but not much attention is paid to them. In this paper, we point out that C–R lensing events provide an important channel to detect planets in binaries, both in close and wide binary systems. Detecting planets through the C–R lensing event channel is possible because the planet-induced perturbation occurs in the same region of the C–R lensing-induced anomaly and thus the existence of the planet can be identified by the additional deviation in the central perturbation. By presenting the analysis of the actually observed C–R lensing event OGLE-2015-BLG-1319, we demonstrate that dense and high-precision coverage of a C–R lensing-induced perturbation can provide a strong constraint on the existence of a planet in a wide range of planet parameters. The sample of an increased number of microlensing planets in binary systems will provide important observational constraints in giving shape to the details of planet formation, which have been restricted to the case of single stars to date.

Small-scale structure and the Lyman-α forest baryon acoustic oscillation feature

Science.gov (United States)

Hirata, Christopher M.

2018-02-01

The baryon-acoustic oscillation (BAO) feature in the Lyman-α forest is a key probe of the cosmic expansion rate at redshifts z ˜ 2.5, well before dark energy is believed to have become significant. A key advantage of the BAO as a standard ruler is that it is a sharp feature and hence is more robust against broad-band systematic effects than other cosmological probes. However, if the Lyman-α forest transmission is sensitive to the initial streaming velocity of the baryons relative to the dark matter, then the BAO peak position can be shifted. Here we investigate this sensitivity using a suite of hydrodynamic simulations of small regions of the intergalactic medium with a range of box sizes and physics assumptions; each simulation starts from initial conditions at the kinematic decoupling era (z ˜ 1059), undergoes a discrete change from neutral gas to ionized gas thermal evolution at reionization (z ˜ 8), and is finally processed into a Lyman-α forest transmitted flux cube. Streaming velocities suppress small-scale structure, leading to less violent relaxation after reionization. The changes in the gas distribution and temperature-density relation at low redshift are more subtle, due to the convergent temperature evolution in the ionized phase. The change in the BAO scale is estimated to be of the order of 0.12 per cent at z = 2.5; some of the major uncertainties and avenues for future improvement are discussed. The predicted streaming velocity shift would be a subdominant but not negligible effect (of order 0.26σ) for the upcoming DESI Lyman-α forest survey, and exceeds the cosmic variance floor.

Lyman-alpha transit observations of the warm rocky exoplanet GJ1132b

Science.gov (United States)

Waalkes, William; Berta-Thompson, Zachory K.; Charbonneau, David; Irwin, Jonathan; Newton, Elisabeth; Dittmann, Jason; Bourrier, Vincent; Ehrenreich, David; Kempton, Eliza; Will

2018-06-01

GJ1132b is one of the few known Earth-sized planets, and at 12pc away it is also one of the closest known transiting planets. With an equilibrium temperature of 500 K, this planet is too hot to be habitable but we can use it to learn about the presence and volatile content of rocky planet atmospheres around M dwarf stars. Using Hubble STIS spectra obtained during primary transit, we search for a Lyman-α transit. If we were to observe a deep Lyman-α transit, that would indicate the presence of a neutral hydrogen envelope flowing from GJ1132b. On the other hand, ruling out deep absorption from neutral hydrogen may indicate that this planet has either retained its volatiles or lost them very early in the star’s life. We carry out this analysis by extracting 1D spectra from the STIS pipeline, splitting the time-tagged spectra into higher resolution samples, and producing light curves of the red and blue wings of the Lyman-α line. We fit for the baseline stellar flux and transit depths in order to constrain the characteristics of the cloud of neutral hydrogen gas that may surround the planet. We do not conclusively detect a transit but the results provide an upper limit for the transit depth. We also analyze the stellar variability and Lyman-α spectrum of GJ1132, a slowly-rotating 0.18 solar mass M dwarf with previously uncharacterized UV activity. Understanding the role that UV variability plays in planetary atmospheres and volatile retention is crucial to assess atmospheric evolution and the habitability of cooler rocky planets.

BRIGHT STRONGLY LENSED GALAXIES AT REDSHIFT z ∼ 6-7 BEHIND THE CLUSTERS ABELL 1703 AND CL0024+16

International Nuclear Information System (INIS)

Zheng, W.; Bradley, L. D.; Ford, H. C.; Shu, X.W.; Bouwens, R. J.; Illingworth, G. D.; BenItez, N.; Broadhurst, T.; Zitrin, A.; Frye, B.; Infante, L.; Jee, M. J.; Motta, V.

2009-01-01

We report on the discovery of three bright, strongly lensed objects behind Abell 1703 and CL0024+16 from a dropout search over 25 arcmin 2 of deep NICMOS data, with deep ACS optical coverage. They are undetected in the deep ACS images below 8500 A and have clear detections in the J and H bands. Fits to the ACS, NICMOS, and IRAC data yield robust photometric redshifts in the range z ∼ 6-7 and largely rule out the possibility that they are low-redshift interlopers. All three objects are extended, and resolved into a pair of bright knots. The bright i-band dropout in Abell 1703 has an H-band AB magnitude of 23.9, which makes it one of the brightest known galaxy candidates at z > 5.5. Our model fits suggest a young, massive galaxy only ∼60 million years old with a mass of ∼10 10 M sun . The dropout galaxy candidates behind CL0024+16 are separated by 2.''5 (∼2 kpc in the source plane), and have H-band AB magnitudes of 25.0 and 25.6. Lensing models of CL0024+16 suggest that the objects have comparable intrinsic magnitudes of AB ∼27.3, approximately one magnitude fainter than L* at z ∼ 6.5. Their similar redshifts, spectral energy distribution, and luminosities, coupled with their very close proximity on the sky, suggest that they are spatially associated, and plausibly are physically bound. Combining this sample with two previously reported, similarly magnified galaxy candidates at z ∼ 6-8, we find that complex systems with dual nuclei may be a common feature of high-redshift galaxies.

New results on strong-interaction effects in antiprotonic hydrogen

CERN Document Server

Gotta, D; Augsburger, M A; Borchert, G L; Castelli, C M; Chatellard, D; El-Khoury, P; Egger, J P; Gorke, H; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Nelms, N; Rashid, K; Schult, O W B; Siems, T; Simons, L M

1999-01-01

Lyman and Balmer transitions of antiprotonic hydrogen and deuterium have been measured at the low-energy antiproton ring LEAR at CERN in order to determine the strong interaction effects. The X-rays were detected using charge-coupled devices (CCDs) and a reflection type crystal spectrometer. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (33 refs).

An integral-field spectroscopic strong lens survey

International Nuclear Information System (INIS)

Bolton, Adam S; Burles, Scott

2007-01-01

We present the observational results of a survey for strong gravitational lens systems consisting of extended emission-line galaxies lensed by intervening early-type galaxies, conducted using integral field units (IFUs) of the Magellan IMACS and Gemini GMOS-N spectrographs. These data are highly valuable for corroborating the lensing interpretation of Hubble Space Telescope imaging data. We show that in many cases, ground-based IFU spectroscopy is in fact competitive with space-based imaging for the measurement of the mass model parameters of the lensing galaxy. We demonstrate a novel technique of three-dimensional gravitational lens modeling for a single lens system with a resolved lensed rotation curve. We also describe the details of our custom IFU data analysis software, which performs optimal multi-fiber extraction, relative and absolute wavelength calibration to a few hundredths of a pixel RMS and nearly Poisson-limited sky subtraction

Stationary inverted Lyman population formed from incandescently heated hydrogen gas with certain catalysts

International Nuclear Information System (INIS)

Mills, Randell L; Ray, Paresh C; Mayo, Robert M

2003-01-01

A new chemically generated plasma source is reported. The presence of gaseous Rb + or K + ions with thermally dissociated hydrogen formed a low applied temperature, extremely low voltage plasma called a resonant transfer or rt-plasma having strong vacuum ultraviolet emission. We propose an energetic catalytic reaction involving a resonant energy transfer between hydrogen atoms and Rb + or 2K + since Rb + to Rb 2+ , 2K + to K + K 2+ , and K to K 3+ each provide a reaction with a net enthalpy equal to the potential energy of atomic hydrogen. Remarkably, a stationary inverted Lyman population was observed; thus, these catalytic reactions may pump a cw HI laser as predicted by a collisional radiative model used to determine that the observed overpopulation was above threshold

DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES

International Nuclear Information System (INIS)

Hezaveh, Yashar; Holder, Gilbert; Dalal, Neal; Kuhlen, Michael; Marrone, Daniel; Murray, Norman; Vieira, Joaquin

2013-01-01

We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of ∼10 8 M ☉ with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a ∼55% probability of detecting a substructure with M > 10 8 M ☉ with more than 5σ detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of ∼100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

3C 220.3: A radio galaxy lensing a submillimeter galaxy

Energy Technology Data Exchange (ETDEWEB)

Haas, Martin; Westhues, Christian; Chini, Rolf [Astronomisches Institut, Ruhr Universität, Bochum (Germany); Leipski, Christian; Klaas, Ulrich; Meisenheimer, Klaus [Max-Planck-Institut für Astronomie, Heidelberg (Germany); Barthel, Peter; Koopmans, Léon V. E. [Kapteyn Astronomical Institute, University of Groningen (Netherlands); Wilkes, Belinda J.; Bussmann, R. Shane; Willner, S. P.; Ashby, Matthew L. N.; Kuraszkiewicz, Joanna [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Vegetti, Simona [Max-Planck-Institut für Astrophysik, Garching (Germany); Clements, David L. [Imperial College, London (United Kingdom); Fassnacht, Christopher D. [University of California, Davis, CA (United States); Horesh, Assaf [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA (United States); Lagattuta, David J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn (Australia); Stern, Daniel; Wylezalek, Dominika, E-mail: haas@astro.rub.de [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States)

2014-07-20

Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1''.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1''.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1''.02) and B (0''.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, M/L{sub i}∼8±4 M{sub ⊙} L{sub ⊙}{sup −1}, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a

Red nuggets grow inside-out: evidence from gravitational lensing

NARCIS (Netherlands)

Oldham, Lindsay; Auger, Matthew W.; Fassnacht, Christopher D.; Treu, Tommaso; Brewer, Brendon J.; Koopmans, L. V. E.; Lagattuta, David; Marshall, Philip; McKean, John; Vegetti, Simona

We present a new sample of strong gravitational lens systems where both the foreground lenses and background sources are early-type galaxies. Using imaging from Hubble Space Telescope (HST)/Advanced Camera for Studies (ACS) and Keck/NIRC2, we model the surface brightness distributions and show that

Acoustic lenses

International Nuclear Information System (INIS)

Kittmer, C.A.

1983-03-01

Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

The skewed weak lensing likelihood: why biases arise, despite data and theory being sound.

Science.gov (United States)

Sellentin, Elena; Heymans, Catherine; Harnois-Déraps, Joachim

2018-04-01

We derive the essentials of the skewed weak lensing likelihood via a simple Hierarchical Forward Model. Our likelihood passes four objective and cosmology-independent tests which a standard Gaussian likelihood fails. We demonstrate that sound weak lensing data are naturally biased low, since they are drawn from a skewed distribution. This occurs already in the framework of ΛCDM. Mathematically, the biases arise because noisy two-point functions follow skewed distributions. This form of bias is already known from CMB analyses, where the low multipoles have asymmetric error bars. Weak lensing is more strongly affected by this asymmetry as galaxies form a discrete set of shear tracer particles, in contrast to a smooth shear field. We demonstrate that the biases can be up to 30% of the standard deviation per data point, dependent on the properties of the weak lensing survey and the employed filter function. Our likelihood provides a versatile framework with which to address this bias in future weak lensing analyses.

DARK MATTER SUBSTRUCTURE DETECTION USING SPATIALLY RESOLVED SPECTROSCOPY OF LENSED DUSTY GALAXIES

Energy Technology Data Exchange (ETDEWEB)

Hezaveh, Yashar; Holder, Gilbert [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Dalal, Neal [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Kuhlen, Michael [Theoretical Astrophysics Center, University of California, Berkeley, CA 94720 (United States); Marrone, Daniel [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Murray, Norman [CITA, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8 (Canada); Vieira, Joaquin [California Institute of Technology, 1200 East California Blvd, MC 249-17, Pasadena, CA 91125 (United States)

2013-04-10

We investigate how strong lensing of dusty, star-forming galaxies (DSFGs) by foreground galaxies can be used as a probe of dark matter halo substructure. We find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters. In particular, we find that modeling of the full, three-dimensional (angular position and radial velocity) data can significantly facilitate substructure detection, increasing the sensitivity of observables to lower mass subhalos. We carry out simulations of lensed dusty sources observed by early ALMA (Cycle 1) and use a Fisher matrix analysis to study the parameter degeneracies and mass detection limits of this method. We find that even with conservative assumptions, it is possible to detect galactic dark matter subhalos of {approx}10{sup 8} M{sub Sun} with high significance in most lensed DSFGs. Specifically, we find that in typical DSFG lenses, there is a {approx}55% probability of detecting a substructure with M > 10{sup 8} M{sub Sun} with more than 5{sigma} detection significance in each lens, if the abundance of substructure is consistent with previous lensing results. The full ALMA array, with its significantly enhanced sensitivity and resolution, should improve these estimates considerably. Given the sample of {approx}100 lenses provided by surveys such as the South Pole Telescope, our understanding of dark matter substructure in typical galaxy halos is poised to improve dramatically over the next few years.

Additive manufacturing of tunable lenses

Science.gov (United States)

Schlichting, Katja; Novak, Tobias; Heinrich, Andreas

2017-02-01

Individual additive manufacturing of optical systems based on 3D Printing offers varied possibilities in design and usage. In addition to the additive manufacturing procedure, the usage of tunable lenses allows further advantages for intelligent optical systems. Our goal is to bring the advantages of additive manufacturing together with the huge potential of tunable lenses. We produced tunable lenses as a bundle without any further processing steps, like polishing. The lenses were designed and directly printed with a 3D Printer as a package. The design contains the membrane as an optical part as well as the mechanical parts of the lens, like the attachments for the sleeves which contain the oil. The dynamic optical lenses were filled with an oil. The focal length of the lenses changes due to a change of the radius of curvature. This change is caused by changing the pressure in the inside of the lens. In addition to that, we designed lenses with special structures to obtain different areas with an individual optical power. We want to discuss the huge potential of this technology for several applications. Further, an appropriate controlling system is needed. Wéll show the possibilities to control and regulate the optical power of the lenses. The lenses could be used for illumination tasks, and in the future, for individual measurement tasks. The main advantage is the individuality and the possibility to create an individual design which completely fulfills the requirements for any specific application.

Nanofocusing refractive X-ray lenses

Energy Technology Data Exchange (ETDEWEB)

Boye, Pit

2010-02-05

This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

Nanofocusing refractive X-ray lenses

International Nuclear Information System (INIS)

Boye, Pit

2010-01-01

This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

Lyman-alpha clouds as a relic of primordial density fluctuations

International Nuclear Information System (INIS)

Bond, J.R.; Szalay, A.S.; Silk, J.

1988-01-01

Primordial density fluctuations are studied using a CDM model and primordial clouds some of which are expanding, driven by pressure gradients created when the medium is photionized, and some of which are massive enough to continue collapsing in spite of the pressure. Normalization of CDM models to the clustering properties on large scales are used to predict the parameters of collapsing clouds of subgalactic mass at early epochs. It is shown that the abundance and dimensions of these clouds are comparable to those of the Lyman-alpha systems. The evolutionary history of the clouds is computed, utilizing a spherically symmetric hydrodynamics code with the dark matter treated as a collisionless fluid, and the H I column density distribution is evaluated as a function of N(H I) and redshift. The observed cloud parameters come out naturally in the CDM model and suggest that Lyman-alpha clouds are the missing link between primordial density fluctuations and the formation of galaxies. 31 references

The Lyman Alpha Imaging-Monitor Experiment (LAIME) for TESIS/CORONAS-PHOTON

Science.gov (United States)

Damé, L.; Koutchmy, S.; Kuzin, S.; Lamy, P.; Malherbe, J.-M.; Noëns, J.-C.

LAIME the Lyman Alpha Imaging-Monitor Experiment is a remarkably simple no mechanisms and compact 100x100x400 mm full Sun imager to be flown with TESIS on the CORONAS-PHOTON mission launch expected before mid-2008 As such it will be the only true chromospheric imager to be flown in the next years supporting TESIS EUV-XUV imaging SDO and the Belgian LYRA Lyman Alpha flux monitor on the ESA PROBA-2 microsatellite launch expected in September 2007 We will give a short description of this unique O60 mm aperture imaging telescope dedicated to the investigating of the magnetic sources of solar variability in the UV and chromospheric and coronal disruptive events rapid waves Moreton waves disparitions brusques of prominences filaments eruptions and CMEs onset The resolution pixel is 2 7 arcsec the field of view 1 4 solar radius and the acquisition cadence could be as high as 1 image minute The back thinned E2V CCD in the focal plane is using frame transfer to avoid shutter and mechanisms Further more the double Lyman Alpha filtering allows a 40 AA FWHM bandwidth and excellent rejection yet providing a vacuum seal design of the telescope MgF2 entrance window Structural stability of the telescope focal length 1 m is preserved by a 4-INVAR bars design with Aluminium compensation in a large pm 10 o around 20 o

An unusually strong Einstein ring in the radio source PKS1830-211

International Nuclear Information System (INIS)

Jauncey, D.L.

1991-01-01

RADIO observations of the strong, flat-spectrum radio source PKS1830-211 revealed a double structure, with a separation of 1 arcsec, suggesting that it might be a gravitationally lensed object. We have now obtained high-resolution radio images of PKS1830-211 from several interferometric radiotelescope networks, which show an unusual elliptical ring-like structure connecting the two brighter components. The presence of the ring, and the similarity of the two brighter spots, argue strongly that this is indeed a gravitationally lensed system, specifically an Einstein ring in which lens and lensed object are closely aligned. Although the source is close to the galactic plane, it seems that both the lens and background (lensed) object are extragalactic. This object is one hundred times brighter than either of the two previously discovered radio Einstein rings, and is among the six brightest flat-spectrum sources in the sky. Its brightness makes it a peculiar object: it must involve either a chance alignment of a lensing object with an unusually bright background source, or an alignment with a less bright object but amplified to an unusual degree. (author)

Pulsar emission amplified and resolved by plasma lensing in an eclipsing binary.

Science.gov (United States)

Main, Robert; Yang, I-Sheng; Chan, Victor; Li, Dongzi; Lin, Fang Xi; Mahajan, Nikhil; Pen, Ue-Li; Vanderlinde, Keith; van Kerkwijk, Marten H

2018-05-01

Radio pulsars scintillate because their emission travels through the ionized interstellar medium along multiple paths, which interfere with each other. It has long been realized that, independent of their nature, the regions responsible for the scintillation could be used as 'interstellar lenses' to localize pulsar emission regions 1,2 . Most such lenses, however, resolve emission components only marginally, limiting results to statistical inferences and detections of small positional shifts 3-5 . As lenses situated close to their source offer better resolution, it should be easier to resolve emission regions of pulsars located in high-density environments such as supernova remnants 6 or binaries in which the pulsar's companion has an ionized outflow. Here we report observations of extreme plasma lensing in the 'black widow' pulsar, B1957+20, near the phase in its 9.2-hour orbit at which its emission is eclipsed by its companion's outflow 7-9 . During the lensing events, the observed radio flux is enhanced by factors of up to 70-80 at specific frequencies. The strongest events clearly resolve the emission regions: they affect the narrow main pulse and parts of the wider interpulse differently. We show that the events arise naturally from density fluctuations in the outer regions of the outflow, and we infer a resolution of our lenses that is comparable to the pulsar's radius, about 10 kilometres. Furthermore, the distinct frequency structures imparted by the lensing are reminiscent of what is observed for the repeating fast radio burst FRB 121102, providing observational support for the idea that this source is observed through, and thus at times strongly magnified by, plasma lenses 10 .

Gravitational lensing by a Horndeski black hole

Energy Technology Data Exchange (ETDEWEB)

Badia, Javier [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

2017-11-15

In this article we study gravitational lensing by non-rotating and asymptotically flat black holes in Horndeski theory. By adopting the strong deflection limit, we calculate the deflection angle, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to black holes in General Relativity. We analyze the astrophysical consequences in the case of the nearest supermassive black holes. (orig.)

Gravitational lensing by a Horndeski black hole

International Nuclear Information System (INIS)

Badia, Javier; Eiroa, Ernesto F.

2017-01-01

In this article we study gravitational lensing by non-rotating and asymptotically flat black holes in Horndeski theory. By adopting the strong deflection limit, we calculate the deflection angle, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to black holes in General Relativity. We analyze the astrophysical consequences in the case of the nearest supermassive black holes. (orig.)

Are the brightest Lyman Alpha Emitters at zD5.7 primeval galaxies?

Science.gov (United States)

Lidman, Christopher; Hayes, Matthew; Jones, Heath; Meisenheimer, Klaus; Tapken, Christian; Westra, Eduard

2009-04-01

Wide-field, narrow-band surveys have proven to be effective at finding very high redshift galaxies that emit brightly in the Lyman alpha line - the so-called Lyman alpha emitters (LAEs). It was through this technique that the most distant spectroscopically confirmed galaxy, a galaxy at zD6.96 (Iye et al. 2006), was discovered. Considerable effort is currently being spent on discovering these galaxies at ever higher redshifts by extending this technique into the near-IR. In contrast to this effort, there has been relatively little work on understanding these galaxies. In particular, how do LAEs relate to other high redshift galaxies, such as those discovered through drop out techniques, and, more importantly, what role LAEs play in re-ionising the universe, if any. We recently discovered two extremely luminous LAEs at zD5.7. These LAEs are among the brightest LAEs ever discovered at this redshift. In a recent paper by Mao et al. (2007), the brightest LAEs are associated to the most massive halos. One of these targets was successfully observed with the IRAC 3.6 micron imager on Spitzer during cycle 5. These data, when combined with constraints that we derive from our deep ground-based spectroscopic data, indicate that the bulk of the flux at 3.6 microns comes from a stellar population that is considserably older than the stars that dominate the flux in the UV. We propose to complete the project and image the second target. These data will enable us to estimate the age and mass of the stellar burst that produces the Lyman alpha line, to estimate the contribution from an older stellar population and to estimate the fraction of Lyman continuum photons that escape the galaxy and are thus available to re-ionise the universe.

Late Rectal Toxicity on RTOG 94-06: Analysis Using a Mixture Lyman Model

International Nuclear Information System (INIS)

Tucker, Susan L.; Dong Lei; Bosch, Walter R.; Michalski, Jeff; Winter, Kathryn; Mohan, Radhe; Purdy, James A.; Kuban, Deborah; Lee, Andrew K.; Cheung, M. Rex; Thames, Howard D.; Cox, James D.

2010-01-01

Purpose: To estimate the parameters of the Lyman normal-tissue complication probability model using censored time-to-event data for Grade ≥2 late rectal toxicity among patients treated on Radiation Therapy Oncology Group 94-06, a dose-escalation trial designed to determine the maximum tolerated dose for three-dimensional conformal radiotherapy of prostate cancer. Methods and Materials: The Lyman normal-tissue complication probability model was fitted to data from 1,010 of the 1,084 patients accrued on Radiation Therapy Oncology Group 94-06 using an approach that accounts for censored observations. Separate fits were obtained using dose-volume histograms for whole rectum and dose-wall histograms for rectal wall. Results: With a median follow-up of 7.2 years, the crude incidence of Grade ≥2 late rectal toxicity was 15% (n = 148). The parameters of the Lyman model fitted to dose-volume histograms data, with 95% profile-likelihood confidence intervals, were TD 50 = 79.1 Gy (75.3 Gy, 84.3 Gy), m = 0.146 (0.107, 0.225), and n = 0.077 (0.041, 0.156). The fit based on dose-wall histogram data was not significantly different. Patients with cardiovascular disease had a significantly higher incidence of late rectal toxicity (p = 0.015), corresponding to a dose-modifying factor of 5.3%. No significant association with late rectal toxicity was found for diabetes, hypertension, rectal volume, rectal length, neoadjuvant hormone therapy, or prescribed dose per fraction (1.8 Gy vs. 2 Gy). Conclusions: These results, based on a large cohort of patients from a multi-institutional trial, are expected to be widely representative of the ability of the Lyman model to describe the long-term risk of Grade ≥2 late rectal toxicity after three-dimensional conformal radiotherapy of prostate cancer.

Discovery of four gravitational lensing systems by clusters in the SDSS DR6

International Nuclear Information System (INIS)

Wen Zhonglue; Han Jinlin; Xu Xiangyang; Jiang Yunying; Guo Zhiqing; Wang Pengfei; Liu Fengshan

2009-01-01

We report the discovery of 4 strong gravitational lensing systems by visual inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data Release 6 (SDSS DR6). Two of the four systems show Einstein rings while the others show tangential giant arcs. These arcs or rings have large angular separations (> 8) from the bright central galaxies and show bluer color compared with the red cluster galaxies. In addition, we found 5 probable and 4 possible lenses by galaxy clusters. (letters)

Statistics of gravitational lenses. III. Astrophysical consequences of quasar lensing

International Nuclear Information System (INIS)

Ostriker, J.P.; Vietri, M.

1986-01-01

The method of Schmidt and Green (1983) for calculating the luminosity function of quasars is combined with gravitational-lensing theory to compute expected properties of lensed systems. Multiple quasar images produced by galaxies are of order 0.001 of the observed quasars, with the numbers over the whole sky calculated to be (0.86, 120, 1600) to limiting B magnitudes of (16, 19, 22). The amount of false evolution is small except for an interesting subset of apparently bright, large-redshift objects for which minilensing by starlike objects may be important. Some of the BL Lac objects may be in this category, with the galaxy identified as the parent object really a foreground object within which stars have lensed a background optically violent variable quasar. 24 references

Gravitational lensing

CERN Document Server

Dodelson, Scott

2017-01-01

Gravitational lensing is a consequence of general relativity, where the gravitational force due to a massive object bends the paths of light originating from distant objects lying behind it. Using very little general relativity and no higher level mathematics, this text presents the basics of gravitational lensing, focusing on the equations needed to understand the phenomena. It then applies them to a diverse set of topics, including multiply imaged objects, time delays, extrasolar planets, microlensing, cluster masses, galaxy shape measurements, cosmic shear, and lensing of the cosmic microwave background. This approach allows undergraduate students and others to get quickly up to speed on the basics and the important issues. The text will be especially relevant as large surveys such as LSST and Euclid begin to dominate the astronomical landscape. Designed for a one semester course, it is accessible to anyone with two years of undergraduate physics background.

Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift

Science.gov (United States)

Goncalves, Thiago S.; Overzier, Roderik; Basu-Zych, Antara; Martin, D. Christopher

2011-01-01

Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe (z approximately equal to 0.2), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.

30 CFR 18.30 - Windows and lenses.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed in...

Golden gravitational lensing systems from the Sloan Lens ACS Survey - II. SDSS J1430+4105: a precise inner total mass profile from lensing alone

Science.gov (United States)

Eichner, Thomas; Seitz, Stella; Bauer, Anne

2012-12-01

We study the Sloan Lens ACS (SLACS) survey strong-lensing system SDSS J1430+4105 at zl = 0.285. The lensed source (zs = 0.575) of this system has a complex morphology with several subcomponents. Its subcomponents span a radial range from 4 to 10 kpc in the plane of the lens. Therefore, we can constrain the slope of the total projected mass profile around the Einstein radius from lensing alone. We measure a density profile that is slightly but not significantly shallower than isothermal at the Einstein radius. We decompose the mass of the lensing galaxy into a de Vaucouleurs component to trace the stars and an additional dark component. The spread of multiple-image components over a large radial range also allows us to determine the amplitude of the de Vaucouleurs and dark matter components separately. We get a mass-to-light ratio of M de Vauc LB ≈ (5.5±1.5) M⊙L⊙,B and a dark matter fraction within the Einstein radius of ≈20 to 40 per cent. Modelling the star formation history assuming composite stellar populations at solar metallicity to the galaxy's photometry yields a mass-to-light ratio of M, salp LB ≈ 4.0-1.3+0.6 M⊙L⊙,B and M, chab LB ≈ 2.3-0.8+0.3 M⊙L⊙,B for Salpeter and Chabrier initial mass functions, respectively. Hence, the mass-to-light ratio derived from lensing is more Salpeter like, in agreement with results for massive Coma galaxies and other nearby massive early-type galaxies. We examine the consequences of the galaxy group in which the lensing galaxy is embedded, showing that it has little influence on the mass-to-light ratio obtained for the de Vaucouleurs component of the lensing galaxy. Finally, we decompose the projected, azimuthally averaged 2D density distribution of the de Vaucouleurs and dark matter components of the lensing signal into spherically averaged 3D density profiles. We can show that the 3D dark and luminous matter density within the Einstein radius (REin ≈ 0.6 Reff) of this SLACS galaxy is similar to the

Comparison of Lyman-alpha and LI-COR infrared hygrometers for airborne measurement of turbulent fluctuations of water vapour

Science.gov (United States)

Lampert, Astrid; Hartmann, Jörg; Pätzold, Falk; Lobitz, Lennart; Hecker, Peter; Kohnert, Katrin; Larmanou, Eric; Serafimovich, Andrei; Sachs, Torsten

2018-05-01

To investigate if the LI-COR humidity sensor can be used as a replacement of the Lyman-alpha sensor for airborne applications, the measurement data of the Lyman-alpha and several LI-COR sensors are analysed in direct intercomparison flights on different airborne platforms. One vibration isolated closed-path and two non-isolated open-path LI-COR sensors were installed on a Dornier 128 twin engine turbo-prop aircraft. The closed-path sensor provided absolute values and fluctuations of the water vapour mixing ratio in good agreement with the Lyman-alpha. The signals of the two open-path sensors showed considerable high-frequency noise, and the absolute value of the mixing ratio was observed to drift with time in this vibrational environment. On the helicopter-towed sensor system Helipod, with very low vibration levels, the open-path LI-COR sensor agreed very well with the Lyman-alpha sensor over the entire frequency range up to 3 Hz. The results show that the LI-COR sensors are well suited for airborne measurements of humidity fluctuations, provided that a vibrationless environment is given, and this turns out to be more important than close sensor spacing.

Discovery of a transient U-band dropout in a lyman break survey: A tidally disrupted star at z=3.3?

International Nuclear Information System (INIS)

Stern, Daniel; van Dokkum, P.G.; Nugent, Peter; Sand, D.J.; Ellis, R.S.; Sullivan, Mark; Bloom, J.S.; Frail, D.A.; Kneib, J.-P.; Koopmans, L.V.E.; Treu, Tommaso

2004-01-01

We report the discovery of a transient source in the central regions of galaxy cluster A267. The object, which we call ''PALS-1'', was found in a survey aimed at identifying highly magnified Lyman break galaxies in the fields of intervening rich clusters. At discovery, the source had Un>24:7 (2 ; AB), g 1/4 21:96 0:12, and very blue g r and ri colors; i.e., PALS-1 was a ''U-band dropout'', characteristic of star-forming galaxies and quasars at z 3. However, 3 months later the source had faded by more than 3 mag. Further observations showed a continued decline in luminosity, to R>26:4 at 7 months after discovery. Although the apparent brightness suggests a supernova at roughly the cluster redshift, we show that the photometry and light curve argue against any known type of supernova at any redshift. The spectral energy distribution and location near the center of a galaxy cluster are consistent with the hypothesis that PALS-1 is a gravitationally lensed transient at z 3:3. If this interpretation is correct, the source is magnified by a factor of 4 7, and two counter images are predicted. Our lens model predicts that there are time delays between the three images of 110 yr and that we have witnessed the final occurrence of the transient. The intense luminosity (MAB 23:5 after correcting for lensing) and blue UV continuum (implying T k50; 000 K) argue that the source may have been a flare resulting from the tidal disruption of a star by a 106108 M black hole. Regardless of its physical nature, PALS-1 highlights the importance of monitoring regions of high magnification in galaxy clusters for distant time-varying phenomena

Gabor lenses

International Nuclear Information System (INIS)

Mobley, R.M.; Gamml, G.; Maschke, A.W.

1979-01-01

Stable operation of Gabor lenses has been reported by at least three experimental groups. At Brookhaven, several lens designs have been tried since February, 1978 with very good results. The lens concept is simple, operation is less complicated than anticipated, and the focussing strengths attainable make them very attractive alternatives to magnetic focussing for heavy ion beams at low energies. Results obtained with five different configurations are presented. The lenses work well, concern is now with fine details of their beam-optical performance

Impact of Lyman alpha pressure on metal-poor dwarf galaxies

Science.gov (United States)

Kimm, Taysun; Haehnelt, Martin; Blaizot, Jérémy; Katz, Harley; Michel-Dansac, Léo; Garel, Thibault; Rosdahl, Joakim; Teyssier, Romain

2018-04-01

Understanding the origin of strong galactic outflows and the suppression of star formation in dwarf galaxies is a key problem in galaxy formation. Using a set of radiation-hydrodynamic simulations of an isolated dwarf galaxy embedded in a 1010 M⊙ halo, we show that the momentum transferred from resonantly scattered Lyman-α (Lyα) photons is an important source of stellar feedback which can shape the evolution of galaxies. We find that Lyα feedback suppresses star formation by a factor of two in metal-poor galaxies by regulating the dynamics of star-forming clouds before the onset of supernova explosions (SNe). This is possible because each Lyα photon resonantly scatters and imparts ˜10-300 times greater momentum than in the single scattering limit. Consequently, the number of star clusters predicted in the simulations is reduced by a factor of ˜5, compared to the model without the early feedback. More importantly, we find that galactic outflows become weaker in the presence of strong Lyα radiation feedback, as star formation and associated SNe become less bursty. We also examine a model in which radiation field is arbitrarily enhanced by a factor of up to 10, and reach the same conclusion. The typical mass-loading factors in our metal-poor dwarf system are estimated to be ˜5-10 near the mid-plane, while it is reduced to ˜1 at larger radii. Finally, we find that the escape of ionizing radiation and hence the reionization history of the Universe is unlikely to be strongly affected by Lyα feedback.

Stationary inverted Lyman population formed from incandescently heated hydrogen gas with certain catalysts

Energy Technology Data Exchange (ETDEWEB)

Mills, Randell L; Ray, Paresh C; Mayo, Robert M [BlackLight Power, Inc., 493 Old Trenton Road, Cranbury, NJ 08512 (United States)

2003-07-07

A new chemically generated plasma source is reported. The presence of gaseous Rb{sup +} or K{sup +} ions with thermally dissociated hydrogen formed a low applied temperature, extremely low voltage plasma called a resonant transfer or rt-plasma having strong vacuum ultraviolet emission. We propose an energetic catalytic reaction involving a resonant energy transfer between hydrogen atoms and Rb{sup +} or 2K{sup +} since Rb{sup +} to Rb{sup 2+}, 2K{sup +} to K + K{sup 2+}, and K to K{sup 3+} each provide a reaction with a net enthalpy equal to the potential energy of atomic hydrogen. Remarkably, a stationary inverted Lyman population was observed; thus, these catalytic reactions may pump a cw HI laser as predicted by a collisional radiative model used to determine that the observed overpopulation was above threshold.

Gravitational lenses and cosmological evolution

International Nuclear Information System (INIS)

Peacock, J.A.

1982-01-01

The effect of gravitational lensing on the apparent cosmological evolution of extragalactic radio sources is investigated. Models for a lens population consisting of galaxies and clusters of galaxies are constructed and used to calculate the distribution of amplification factors caused by lensing. Although many objects at high redshifts are predicted to have flux densities altered by 10 to 20 per cent relative to a homogeneous universe, flux conservation implies that de-amplification is as common as amplification. The effects on cosmological evolution as inferred from source counts and redshift data are thus relatively small; the slope of the counts is not large enough for intrinsically rare lensing events of high amplitude to corrupt observed samples. Lensing effects may be of greater importance for optically selected quasars, where lenses of mass as low as approximately 10 -4 solar mass can cause large amplifications. (author)

NO OVERDENSITY OF LYMAN-ALPHA EMITTING GALAXIES AROUND A QUASAR AT z  ∼ 5.7

International Nuclear Information System (INIS)

Mazzucchelli, C.; Bañados, E.; Decarli, R.; Farina, E. P.; Venemans, B. P.; Walter, F.; Overzier, R.

2017-01-01

Bright quasars, observed when the universe was less than one billion years old ( z  > 5.5), are known to host massive black holes (∼10 9 M ⊙ ) and are thought to reside in the center of massive dark matter overdensities. In this picture, overdensities of galaxies are expected around high-redshift quasars. However, observations based on the detection of Lyman-break galaxies (LBGs) around these quasars do not offer a clear picture: this may be due to the uncertain redshift constraints of LBGs, which are solely selected through broadband filters. To circumvent such uncertainties, we here perform a search for Lyman-alpha emitting galaxies (LAEs) in the field of the quasar PSO J215.1512–16.0417 at z  ∼ 5.73, through narrowband deep imaging with FORS2 at the Very Large Telescope. We study an area of 37 arcmin 2 , i.e., ∼206 comoving Mpc 2 at the redshift of the quasar. We find no evidence of an overdensity of LAEs in the quasar field with respect to blank-field studies. Possible explanations for these findings may be that our survey volume is too small, or that the strong ionizing radiation from the quasar hinders galaxy formation in its immediate proximity. Another possibility is that these quasars are not situated in the dense environments predicted by some simulations.

NO OVERDENSITY OF LYMAN-ALPHA EMITTING GALAXIES AROUND A QUASAR AT z  ∼ 5.7

Energy Technology Data Exchange (ETDEWEB)

Mazzucchelli, C.; Bañados, E.; Decarli, R.; Farina, E. P.; Venemans, B. P.; Walter, F. [Max Planck Institute für Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Overzier, R. [Observatório Nacional, Rua José Cristino, 77. CEP 20921-400, São Cristóvão, Rio de Janeiro-RJ (Brazil)

2017-01-01

Bright quasars, observed when the universe was less than one billion years old ( z  > 5.5), are known to host massive black holes (∼10{sup 9} M {sub ⊙}) and are thought to reside in the center of massive dark matter overdensities. In this picture, overdensities of galaxies are expected around high-redshift quasars. However, observations based on the detection of Lyman-break galaxies (LBGs) around these quasars do not offer a clear picture: this may be due to the uncertain redshift constraints of LBGs, which are solely selected through broadband filters. To circumvent such uncertainties, we here perform a search for Lyman-alpha emitting galaxies (LAEs) in the field of the quasar PSO J215.1512–16.0417 at z  ∼ 5.73, through narrowband deep imaging with FORS2 at the Very Large Telescope. We study an area of 37 arcmin{sup 2}, i.e., ∼206 comoving Mpc{sup 2} at the redshift of the quasar. We find no evidence of an overdensity of LAEs in the quasar field with respect to blank-field studies. Possible explanations for these findings may be that our survey volume is too small, or that the strong ionizing radiation from the quasar hinders galaxy formation in its immediate proximity. Another possibility is that these quasars are not situated in the dense environments predicted by some simulations.

USING THE BULLET CLUSTER AS A GRAVITATIONAL TELESCOPE TO STUDY z ∼> 7 LYMAN BREAK GALAXIES

International Nuclear Information System (INIS)

Hall, Nicholas; Bradač, Maruša; Gonzalez, Anthony H.; Treu, Tommaso; Clowe, Douglas; Jones, Christine; Stiavelli, Massimo; Zaritsky, Dennis; Cuby, Jean-Gabriel; Clément, Benjamin

2012-01-01

We use imaging obtained with the Hubble Space Telescope Wide Field Camera 3 to search for z 850 dropouts at z ∼ 7 and J 110 dropouts at z ∼ 9 lensed by the Bullet Cluster. In total we find 10 z 850 dropouts in our 8.27 arcmin 2 field. Using magnification maps from a combined weak- and strong-lensing mass reconstruction of the Bullet Cluster and correcting for estimated completeness levels, we calculate the surface density and luminosity function of our z 850 dropouts as a function of intrinsic (accounting for magnification) magnitude. We find results consistent with published blank field surveys, despite using much shallower data, and demonstrate the effectiveness of cluster surveys in the search for z ∼ 7 galaxies.

Anisotropic Galaxy-Galaxy Lensing in the Illustris-1 Simulation

Science.gov (United States)

Brainerd, Tereasa G.

2017-06-01

In Cold Dark Matter universes, the dark matter halos of galaxies are expected to be triaxial, leading to a surface mass density that is not circularly symmetric. In principle, this "flattening" of the dark matter halos of galaxies should be observable as an anisotropy in the weak galaxy-galaxy lensing signal. The degree to which the weak lensing signal is observed to be anisotropic, however, will depend strongly on the degree to which mass (i.e., the dark matter) is aligned with light in the lensing galaxies. That is, the anisotropy will be maximized when the major axis of the projected mass distribution is well aligned with the projected light distribution of the lens galaxies. Observational studies of anisotropic galaxy-galaxy lensing have found an anisotropic weak lensing signal around massive, red galaxies. Detecting the signal around blue, disky galaxies has, however, been more elusive. A possible explanation for this is that mass and light are well aligned within red galaxies and poorly aligned within blue galaxies (an explanation that is supported by studies of the locations of satellites of large, relatively isolated galaxies). Here we compute the weak lensing signal of isolated central galaxies in the Illustris-1 simulation. We compute the anisotropy of the weak lensing signal using two definitions of the geometry: [1] the major axis of the projected dark matter mass distribution and [2] the major axis of the projected stellar mass. On projected scales less than 15% of the virial radius, an anisotropy of order 10% is found for both definitions of the geometry. On larger scales, the anisotropy computed relative to the major axis of the projected light distribution is less than the anisotropy computed relative to the major axis of the projected dark matter. On projected scales of order the virial radius, the anisotropy obtained when using the major axis of the light is an order of magnitude less than the anisotropy obtained when using the major axis of the

BAYESIAN INFERENCE OF CMB GRAVITATIONAL LENSING

Energy Technology Data Exchange (ETDEWEB)

Anderes, Ethan [Department of Statistics, University of California, Davis, CA 95616 (United States); Wandelt, Benjamin D.; Lavaux, Guilhem [Sorbonne Universités, UPMC Univ Paris 06 and CNRS, UMR7095, Institut d’Astrophysique de Paris, F-75014, Paris (France)

2015-08-01

The Planck satellite, along with several ground-based telescopes, has mapped the cosmic microwave background (CMB) at sufficient resolution and signal-to-noise so as to allow a detection of the subtle distortions due to the gravitational influence of the intervening matter distribution. A natural modeling approach is to write a Bayesian hierarchical model for the lensed CMB in terms of the unlensed CMB and the lensing potential. So far there has been no feasible algorithm for inferring the posterior distribution of the lensing potential from the lensed CMB map. We propose a solution that allows efficient Markov Chain Monte Carlo sampling from the joint posterior of the lensing potential and the unlensed CMB map using the Hamiltonian Monte Carlo technique. The main conceptual step in the solution is a re-parameterization of CMB lensing in terms of the lensed CMB and the “inverse lensing” potential. We demonstrate a fast implementation on simulated data, including noise and a sky cut, that uses a further acceleration based on a very mild approximation of the inverse lensing potential. We find that the resulting Markov Chain has short correlation lengths and excellent convergence properties, making it promising for applications to high-resolution CMB data sets in the future.

Cosmology with weak lensing surveys

International Nuclear Information System (INIS)

Munshi, Dipak; Valageas, Patrick; Waerbeke, Ludovic van; Heavens, Alan

2008-01-01

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

Cosmology with weak lensing surveys

Energy Technology Data Exchange (ETDEWEB)

Munshi, Dipak [Institute of Astronomy, Madingley Road, Cambridge, CB3 OHA (United Kingdom); Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE (United Kingdom)], E-mail: munshi@ast.cam.ac.uk; Valageas, Patrick [Service de Physique Theorique, CEA Saclay, 91191 Gif-sur-Yvette (France); Waerbeke, Ludovic van [University of British Columbia, Department of Physics and Astronomy, 6224 Agricultural Road, Vancouver, BC V6T 1Z1 (Canada); Heavens, Alan [SUPA - Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)

2008-06-15

Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

Gravitational lenses

International Nuclear Information System (INIS)

Turner, E.L.

1989-01-01

The author discusses how gravitational lens studies is becoming a major focus of extragalactic astronomy and cosmology. This review is organized into five parts: an overview of the observational situation, a look at the state of theoretical work on lenses, a detailed look at three recently discovered types of lensing phenomena (luminous arcs, radio rings, quasar-galaxy associations), a review of progress on two old problems in lens studies (deriving unique lens mass distribution models, measurements of differential time delays), and an attempt to look into the future of lens studies

CLASH: COMPLETE LENSING ANALYSIS OF THE LARGEST COSMIC LENS MACS J0717.5+3745 AND SURROUNDING STRUCTURES

International Nuclear Information System (INIS)

Medezinski, Elinor; Lemze, Doron; Ford, Holland; Umetsu, Keiichi; Nonino, Mario; Merten, Julian; Mroczkowski, Tony; Zitrin, Adi; Broadhurst, Tom; Donahue, Megan; Sayers, Jack; Czakon, Nicole; Waizmann, Jean-Claude; Meneghetti, Massimo; Koekemoer, Anton; Coe, Dan; Postman, Marc; Molino, Alberto; Melchior, Peter; Grillo, Claudio

2013-01-01

The galaxy cluster MACS J0717.5+3745 (z = 0.55) is the largest known cosmic lens, with complex internal structures seen in deep X-ray, Sunyaev-Zel'dovich effect, and dynamical observations. We perform a combined weak- and strong-lensing analysis with wide-field BVR c i'z' Subaru/Suprime-Cam observations and 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble. We find consistent weak distortion and magnification measurements of background galaxies and combine these signals to construct an optimally estimated radial mass profile of the cluster and its surrounding large-scale structure out to 5 Mpc h –1 . We find consistency between strong-lensing and weak-lensing in the region where these independent data overlap, –1 . The two-dimensional weak-lensing map reveals a clear filamentary structure traced by distinct mass halos. We model the lensing shear field with nine halos, including the main cluster, corresponding to mass peaks detected above 2.5σ κ . The total mass of the cluster as determined by the different methods is M vir ≈ (2.8 ± 0.4) × 10 15 M ☉ . Although this is the most massive cluster known at z > 0.5, in terms of extreme value statistics, we conclude that the mass of MACS J0717.5+3745 by itself is not in serious tension with ΛCDM, representing only a ∼2σ departure above the maximum simulated halo mass at this redshift

CLASH: COMPLETE LENSING ANALYSIS OF THE LARGEST COSMIC LENS MACS J0717.5+3745 AND SURROUNDING STRUCTURES

Energy Technology Data Exchange (ETDEWEB)

Medezinski, Elinor; Lemze, Doron; Ford, Holland [Department of Physics and Astronomy, The Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Umetsu, Keiichi [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617, Taiwan (China); Nonino, Mario [INAF/Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, I-34143 Trieste (Italy); Merten, Julian; Mroczkowski, Tony [Jet Propulsion Laboratory, California Institute of Technology, MS 169-327, Pasadena, CA 91109 (United States); Zitrin, Adi [Institut für Theoretische Astrophysik, Universität Heidelberg, Zentrum für Astronomie, Philosophenweg 12, D-69120 Heidelberg (Germany); Broadhurst, Tom [Department of Theoretical Physics and History of Science, University of the Basque Country UPV/EHU, P.O. Box 644, E-48080 Bilbao (Spain); Donahue, Megan [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Sayers, Jack; Czakon, Nicole [Division of Physics, Math, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Waizmann, Jean-Claude; Meneghetti, Massimo [Dipartimento di Astronomia, Universit' a di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Koekemoer, Anton; Coe, Dan; Postman, Marc [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21208 (United States); Molino, Alberto [Instituto de Astrofísica de Andalucía (CSIC), E-18080 Granada (Spain); Melchior, Peter [Center for Cosmology and Astro-Particle Physics and Department of Physics, The Ohio State University, Columbus, OH 43210 (United States); Grillo, Claudio, E-mail: elinor@pha.jhu.edu [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Mariesvej 30, DK-2100 Copenhagen (Denmark); and others

2013-11-01

The galaxy cluster MACS J0717.5+3745 (z = 0.55) is the largest known cosmic lens, with complex internal structures seen in deep X-ray, Sunyaev-Zel'dovich effect, and dynamical observations. We perform a combined weak- and strong-lensing analysis with wide-field BVR{sub c} i'z' Subaru/Suprime-Cam observations and 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble. We find consistent weak distortion and magnification measurements of background galaxies and combine these signals to construct an optimally estimated radial mass profile of the cluster and its surrounding large-scale structure out to 5 Mpc h {sup –1}. We find consistency between strong-lensing and weak-lensing in the region where these independent data overlap, <500 kpc h {sup –1}. The two-dimensional weak-lensing map reveals a clear filamentary structure traced by distinct mass halos. We model the lensing shear field with nine halos, including the main cluster, corresponding to mass peaks detected above 2.5σ{sub κ}. The total mass of the cluster as determined by the different methods is M{sub vir} ≈ (2.8 ± 0.4) × 10{sup 15} M{sub ☉}. Although this is the most massive cluster known at z > 0.5, in terms of extreme value statistics, we conclude that the mass of MACS J0717.5+3745 by itself is not in serious tension with ΛCDM, representing only a ∼2σ departure above the maximum simulated halo mass at this redshift.

Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter

Science.gov (United States)

Champey, P.; Kobayashi, K.; Winebarger, A.; Cirtain, J.; Hyde, D.; Robertson, B.; Beabout, D.; Beabout, B.; Stewart, M.

2014-01-01

The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1 percent in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1 percent polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30 percent) quantum efficiency at the Lyman-alpha line. The CLASP cameras were designed to operate with 10 e-/pixel/second dark current, 25 e- read noise, a gain of 2.0 +/- 0.5 and 1.0 percent residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

Mass Modeling of Frontier Fields Cluster MACS J1149.5+2223 Using Strong and Weak Lensing

Science.gov (United States)

Finney, Emily Quinn; Bradač, Maruša; Huang, Kuang-Han; Hoag, Austin; Morishita, Takahiro; Schrabback, Tim; Treu, Tommaso; Borello Schmidt, Kasper; Lemaux, Brian C.; Wang, Xin; Mason, Charlotte

2018-05-01

We present a gravitational-lensing model of MACS J1149.5+2223 using ultra-deep Hubble Frontier Fields imaging data and spectroscopic redshifts from HST grism and Very Large Telescope (VLT)/MUSE spectroscopic data. We create total mass maps using 38 multiple images (13 sources) and 608 weak-lensing galaxies, as well as 100 multiple images of 31 star-forming regions in the galaxy that hosts supernova Refsdal. We find good agreement with a range of recent models within the HST field of view. We present a map of the ratio of projected stellar mass to total mass (f ⋆) and find that the stellar mass fraction for this cluster peaks on the primary BCG. Averaging within a radius of 0.3 Mpc, we obtain a value of ={0.012}-0.003+0.004, consistent with other recent results for this ratio in cluster environments, though with a large global error (up to δf ⋆ = 0.005) primarily due to the choice of IMF. We compare values of f ⋆ and measures of star formation efficiency for this cluster to other Hubble Frontier Fields clusters studied in the literature, finding that MACS1149 has a higher stellar mass fraction than these other clusters but a star formation efficiency typical of massive clusters.

Bright Strongly Lensed Galaxies at Redshift z ~ 6-7 behind the Clusters Abell 1703 and CL0024+16

Science.gov (United States)

Zheng, W.; Bradley, L. D.; Bouwens, R. J.; Ford, H. C.; Illingworth, G. D.; Benítez, N.; Broadhurst, T.; Frye, B.; Infante, L.; Jee, M. J.; Motta, V.; Shu, X. W.; Zitrin, A.

2009-06-01

We report on the discovery of three bright, strongly lensed objects behind Abell 1703 and CL0024+16 from a dropout search over 25 arcmin2 of deep NICMOS data, with deep ACS optical coverage. They are undetected in the deep ACS images below 8500 Å and have clear detections in the J and H bands. Fits to the ACS, NICMOS, and IRAC data yield robust photometric redshifts in the range z ~ 6-7 and largely rule out the possibility that they are low-redshift interlopers. All three objects are extended, and resolved into a pair of bright knots. The bright i-band dropout in Abell 1703 has an H-band AB magnitude of 23.9, which makes it one of the brightest known galaxy candidates at z > 5.5. Our model fits suggest a young, massive galaxy only ~60 million years old with a mass of ~1010 M sun. The dropout galaxy candidates behind CL0024+16 are separated by 2farcs5 (~2 kpc in the source plane), and have H-band AB magnitudes of 25.0 and 25.6. Lensing models of CL0024+16 suggest that the objects have comparable intrinsic magnitudes of AB ~27.3, approximately one magnitude fainter than L* at z ~ 6.5. Their similar redshifts, spectral energy distribution, and luminosities, coupled with their very close proximity on the sky, suggest that they are spatially associated, and plausibly are physically bound. Combining this sample with two previously reported, similarly magnified galaxy candidates at z ~ 6-8, we find that complex systems with dual nuclei may be a common feature of high-redshift galaxies. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities of Research in Astronomy, Inc., under NASA contract NAS5-26555, and at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle

CMB lensing and giant rings

Energy Technology Data Exchange (ETDEWEB)

Rathaus, Ben; Itzhaki, Nissan, E-mail: nitzhaki@post.tau.ac.il, E-mail: ben.rathaus@gmail.com [Raymond and Beverly Sackler Faculty of Exact Sciences, School of Physics and Astronomy, Tel-Aviv University, Ramat-Aviv, 69978 (Israel)

2012-05-01

We study the CMB lensing signature of a pre-inationary particle (PIP), assuming it is responsible for the giant rings anomaly that was found recently in the WMAP data. Simulating Planck-like data we find that generically the CMB lensing signal to noise ratio associated with such a PIP is quite small and it would be difficult to cross correlate the temperature giant rings with the CMB lensing signal. However, if the pre-inationary particle is also responsible for the bulk flow measured from the local large scale structure, which happens to point roughly at the same direction as the giant rings, then the CMB lensing signal to noise ratio is fairly significant.

Planck 2015 results. XV. Gravitational lensing

CERN Document Server

Ade, P.A.R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J.M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P.M.; Macías-Pérez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P.G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Nørgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G.W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J.P.; Reach, W.T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Wehus, I.K.; White, M.; Yvon, D.; Zacchei, A.

2016-01-01

We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40 sigma), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator we detect lensing at a significance of 5 sigma. We cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. Public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40lensing potential power spectrum and that found in the best-fitting LCDM model based on the Planck temperature and polarization power spectra. Using the lensing likelihood alone we obtain a percent-level measurement of ...

On an illusion of superluminal velocities produced by gravitational lenses

International Nuclear Information System (INIS)

Ingel, L.Kh.

1981-01-01

It is noted that gravitational lenses, by focusing the radiation of an object, increase the angle which it subtends. This in turn produces the illusion of an increase in velocities at right angles to the line of sight. Preliminary estimates are made which indicate a rather high probability of strong distortion of the observed velocities

The effects of structure anisotropy on lensing observables in an exact general relativistic setting for precision cosmology

Energy Technology Data Exchange (ETDEWEB)

Troxel, M. A.; Ishak, Mustapha; Peel, Austin, E-mail: troxel@utdallas.edu, E-mail: mishak@utdallas.edu, E-mail: austin.peel@utdallas.edu [Department of Physics, The University of Texas at Dallas, Richardson, TX 75080 (United States)

2014-03-01

The study of relativistic, higher order, and nonlinear effects has become necessary in recent years in the pursuit of precision cosmology. We develop and apply here a framework to study gravitational lensing in exact models in general relativity that are not restricted to homogeneity and isotropy, and where full nonlinearity and relativistic effects are thus naturally included. We apply the framework to a specific, anisotropic galaxy cluster model which is based on a modified NFW halo density profile and described by the Szekeres metric. We examine the effects of increasing levels of anisotropy in the galaxy cluster on lensing observables like the convergence and shear for various lensing geometries, finding a strong nonlinear response in both the convergence and shear for rays passing through anisotropic regions of the cluster. Deviation from the expected values in a spherically symmetric structure are asymmetric with respect to path direction and thus will persist as a statistical effect when averaged over some ensemble of such clusters. The resulting relative difference in various geometries can be as large as approximately 2%, 8%, and 24% in the measure of convergence (1−κ) for levels of anisotropy of 5%, 10%, and 15%, respectively, as a fraction of total cluster mass. For the total magnitude of shear, the relative difference can grow near the center of the structure to be as large as 15%, 32%, and 44% for the same levels of anisotropy, averaged over the two extreme geometries. The convergence is impacted most strongly for rays which pass in directions along the axis of maximum dipole anisotropy in the structure, while the shear is most strongly impacted for rays which pass in directions orthogonal to this axis, as expected. The rich features found in the lensing signal due to anisotropic substructure are nearly entirely lost when one treats the cluster in the traditional FLRW lensing framework. These effects due to anisotropic structures are thus likely to

Gravitational lensing of quasars

CERN Document Server

Eigenbrod, Alexander

2013-01-01

The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced – this phenomenon of cosmic mirage can provide invaluable insights on burning questions, such as the nature of dark matter and dark energy. After presenting the basics of modern cosmology, the book describes active galactic nuclei, the theory of gravitational lensing, and presents a particular numerical technique to improve the resolution of astronomical data. The book then enters the heart of the subject with the description of important applications of gravitational lensing of quasars, such as the measurement of the famous Hubble constant, the determination of the dark matter distribution in galaxies, and the observation of the mysterious inner parts of quasars with much higher r...

Dark-Matter in Galaxies from Gravitational Lensing and Stellar Dynamics Studies

NARCIS (Netherlands)

Koopmans, L. V. E.; Corbett, IF

2010-01-01

Strong gravitational lensing and stellar dynamics provide two complementary methods in the study of the mass distribution of dark matter in galaxies out to redshift of unity. They are particularly powerful in the determination of the total mass and the density profile of mass early-type galaxies on

Lensing of Fast Radio Bursts by Plasma Structures in Host Galaxies

NARCIS (Netherlands)

Cordes, J.M.; Wasserman, I.; Hessels, J.W.T.; Lazio, T.J.W.; Chatterjee, S.; Wharton, R.S.

2017-01-01

The amplitudes of fast radio bursts (FRBs) can be strongly modulated by plasma lenses in their host galaxies, including that of the repeating FRB 121102 at ∼1 Gpc luminosity distance. Caustics require the lens’ dispersion measure depth ({{DM}}{\\ell }), scale size (a), and distance from the source

First Constraints on Fuzzy Dark Matter from Lyman-α Forest Data and Hydrodynamical Simulations.

Science.gov (United States)

Iršič, Vid; Viel, Matteo; Haehnelt, Martin G; Bolton, James S; Becker, George D

2017-07-21

We present constraints on the masses of extremely light bosons dubbed fuzzy dark matter (FDM) from Lyman-α forest data. Extremely light bosons with a de Broglie wavelength of ∼1  kpc have been suggested as dark matter candidates that may resolve some of the current small scale problems of the cold dark matter model. For the first time, we use hydrodynamical simulations to model the Lyman-α flux power spectrum in these models and compare it to the observed flux power spectrum from two different data sets: the XQ-100 and HIRES/MIKE quasar spectra samples. After marginalization over nuisance and physical parameters and with conservative assumptions for the thermal history of the intergalactic medium (IGM) that allow for jumps in the temperature of up to 5000 K, XQ-100 provides a lower limit of 7.1×10^{-22}  eV, HIRES/MIKE returns a stronger limit of 14.3×10^{-22}  eV, while the combination of both data sets results in a limit of 20×10^{-22}  eV (2σ C.L.). The limits for the analysis of the combined data sets increases to 37.5×10^{-22}  eV (2σ C.L.) when a smoother thermal history is assumed where the temperature of the IGM evolves as a power law in redshift. Light boson masses in the range 1-10×10^{-22}  eV are ruled out at high significance by our analysis, casting strong doubts that FDM helps solve the "small scale crisis" of the cold dark matter models.

New constraints on Lyman-α opacity using 92 quasar lines of sight

Science.gov (United States)

Bosman, Sarah E. I.; Fan, Xiaohui; Jiang, Linhua; Reed, Sophie; Matsuoka, Yoshiki; Becker, George; Rorai, Albert

2018-05-01

The large scatter in Lyman-α opacity at z > 5.3 has been an ongoing mystery, prompting a flurry of numerical models. A uniform ultra-violet background has been ruled out at those redshifts, but it is unclear whether any proposed models produce sufficient inhomogeneities. In this paper we provide an update on the measurement which first highlighted the issue: Lyman-α effective optical depth along high-z quasar lines of sight. We nearly triple on the previous sample size in such a study thanks to the cooperation of the DES-VHS, SHELLQs, and SDSS collaborations as well as new reductions and spectra. We find that a uniform UVB model is ruled out at 5.1 < z < 5.3, as well as higher redshifts, which is perplexing. We provide the first such measurements at z ~ 6. None of the numerical models we confronted to this data could reproduce the observed scatter.

The role of contact lenses and ocular TRAUMA in determining Acanthamoeba Keratitis: a case-control study in Italy.

Directory of Open Access Journals (Sweden)

Elena Pacella

2012-03-01

Full Text Available

<strong>Abstract: strong>
<strong>Background: strong>acanthamoeba keratitis (a.k. is a rare secondary infection due to acanthamoeba (a invading the cornea. cofactors of risk may include TrauMa and contact lenses (cL. The objectives of this observational study are to evaluate the occurrence of a.k. in patients accessing the department of Special Senses of the Teaching Hospital “Policlinico umberto I" of rome with ocular infections dur- ing the period from 2005 to 2011, and the role played by risk factors which included contact lenses, TrauMa, sex and age.
<strong>Methods>: a case-control study involving 714 subjects was conducted (350 male and 364 female. all of the patients underwent a thorough ocular examination with confocal microscopy and a review of their medical history to outline relevant variables (contact lens and TrauMa. Statistical analysis calculated the frequency distribution and the odds ratio (or (95%cI for the risk factors "contact lenses" (cL and "TrauMa". The odds ratio (95%cI was adjusted for age and sex trough Logistic regression. <strong>Results>: out of 714 patients, 11 patients (7 male and 4 female with a mean age of 34.09 years (19 to 51 years old were found to be affected by a.k. The age group most afflicted ranged from 30 to 51 years old. Statistical analysis produced a crude or equal to 17.68 (95%cI 2.25-138.89 for cL-a.k. and or equal to 7.71 (95%cI 0.89-66.75 for ocular TrauMa.-a.k. Logistic regression performed to adjust or for age and sex showed the following values, respectively: or*=82.54 (95%cI 3.04-2239.58 and or*=11.52 (95%cI 1.19-111.76.
<strong>Conclusions>: the data highlights an increase in a.k. cases during the 6 year study period. The association between this pathology and the use of contact lenses and/or TrauMa has been statisti- cally proven. The strength of this association increases when the odds ratio (or* is adjusted for the confounding risk factors of

Constraints on early-type galaxy structure from spectroscopically selected gravitational lenses

Science.gov (United States)

Bolton, Adam Stallard

2005-11-01

This thesis describes all aspects of a unique spectroscopic survey for strong galaxy-galaxy gravitational lenses: motivation, candidate selection, ground- based spectroscopic follow-up, Hubble Space Telescope imaging, data analysis, and results on the radial density profile of the lens galaxies. The lens candidates are selected from within the spectroscopic database of the Sloan Digital Sky Survey (SDSS) based on the appearance of two significantly different redshifts along the same line of sight, and lenses are confirmed within the candidate sample by follow-up imaging and spectroscopy. The sample of [approximate]20 early-type lenses presented in this thesis represents the largest single strong-lens galaxy sample discovered and published to date. These lenses probe the mass of the lens galaxies on scales roughly equal to one-half effective radius. We find a dynamical normalization between isothermal lens-model velocity dispersions and aperture-corrected SDSS stellar velocity dispersions of f = s lens /s stars = 0.95 +/- 0.03. By combining lens-model Einstein radii and de Vaucouleurs effective radii with stellar velocity dispersions through the Jeans equation, we find that the logarithmic slope [Special characters omitted.] of the density profile in our lens galaxies (r 0 ( [Special characters omitted.] ) is on average slightly steeper than isothermal ([Special characters omitted.] = 2) with a modest intrinsic scatter. Parameterizing the intrinsic distribution in [Special characters omitted.] as Gaussian, we find a maximum-likelihood mean of [Special characters omitted. ] and standard deviation of s[Special characters omitted.] = [Special characters omitted.] (68% confidence, for isotropic velocity-dispersion models). Our results rule out a single universal logarithmic density slope at >99.995% confidence. The success of this spectroscopic lens survey suggests that similar projects should be considered as an explicit science goal of future redshift surveys. (Copies

Diagnostics of the Solar Wind and Global Heliosphere with Lyman-α Emission Measurements

Science.gov (United States)

Provornikova, E. P.; Izmodenov, V. V.; Laming, J. M.; Strachan, L.; Wood, B. E.; Katushkina, O. A.; Ko, Y.-K.; Tun Beltran, S.; Chakrabarti, S.

2018-02-01

We propose to develop an instrument measuring full sky intensity maps and spectra of interplanetary Lyman-α emission to reveal the global solar wind variability and the nature of the heliosphere and the local interstellar medium.

KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

Energy Technology Data Exchange (ETDEWEB)

STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

2004-10-23

While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

Galaxy–Galaxy Weak-lensing Measurements from SDSS. I. Image Processing and Lensing Signals

Energy Technology Data Exchange (ETDEWEB)

Luo, Wentao [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China); Yang, Xiaohu; Zhang, Jun; Tweed, Dylan [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Fu, Liping; Shu, Chenggang [Shanghai Key Lab for Astrophysics, Shanghai Normal University, 100 Guilin Road, 200234, Shanghai (China); Mo, H. J. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Bosch, Frank C. van den [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Li, Ran [Key Laboratory for Computational Astrophysics, Partner Group of the Max Planck Institute for Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Li, Nan [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Liu, Xiangkun; Pan, Chuzhong [Department of Astronomy, Peking University, Beijing 100871 (China); Wang, Yiran [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Radovich, Mario, E-mail: walt@shao.ac.cn, E-mail: xyang@sjtu.edu.cn [INAF-Osservatorio Astronomico di Napoli, via Moiariello 16, I-80131 Napoli (Italy)

2017-02-10

We present our image processing pipeline that corrects the systematics introduced by the point-spread function (PSF). Using this pipeline, we processed Sloan Digital Sky Survey (SDSS) DR7 imaging data in r band and generated a galaxy catalog containing the shape information. Based on our shape measurements of the galaxy images from SDSS DR7, we extract the galaxy–galaxy (GG) lensing signals around foreground spectroscopic galaxies binned in different luminosities and stellar masses. We estimated the systematics, e.g., selection bias, PSF reconstruction bias, PSF dilution bias, shear responsivity bias, and noise rectification bias, which in total is between −9.1% and 20.8% at 2 σ levels. The overall GG lensing signals we measured are in good agreement with Mandelbaum et al. The reduced χ {sup 2} between the two measurements in different luminosity bins are from 0.43 to 0.83. Larger reduced χ {sup 2} from 0.60 to 1.87 are seen for different stellar mass bins, which is mainly caused by the different stellar mass estimator. The results in this paper with higher signal-to-noise ratio are due to the larger survey area than SDSS DR4, confirming that more luminous/massive galaxies bear stronger GG lensing signals. We divide the foreground galaxies into red/blue and star-forming/quenched subsamples and measure their GG lensing signals. We find that, at a specific stellar mass/luminosity, the red/quenched galaxies have stronger GG lensing signals than their counterparts, especially at large radii. These GG lensing signals can be used to probe the galaxy–halo mass relations and their environmental dependences in the halo occupation or conditional luminosity function framework.

Microbial adhesion to silicone hydrogel lenses: a review.

Science.gov (United States)

Willcox, Mark D P

2013-01-01

Microbial adhesion to contact lenses is believed to be one of the initiating events in the formation of many corneal infiltrative events, including microbial keratitis, that occur during contact lens wear. The advent of silicone hydrogel lenses has not reduced the incidence of these events. This may partly be related to the ability of microbes to adhere to these lenses. The aim of this study was to review the published literature on microbial adhesion to contact lenses, focusing on adhesion to silicone hydrogel lenses. The literature on microbial adhesion to contact lenses was searched, along with associated literature on adverse events that occur during contact lens wear. Particular reference was paid to the years 1995 through 2012 because this encompasses the time when the first clinical trials of silicone hydrogel lenses were reported, and their commercial availability and the publication of epidemiology studies on adverse events were studied. In vitro studies of bacterial adhesion to unworn silicone hydrogel lens have shown that generally, bacteria adhere to these lenses in greater numbers than to the hydroxyethyl methacrylate-based soft lenses. Lens wear has different effects on microbial adhesion, and this is dependent on the type of lens and microbial species/genera that is studied. Biofilms that can be formed on any lens type tend to protect the bacteria and fungi from the effects on disinfectants. Fungal hyphae can penetrate the surface of most types of lenses. Acanthamoeba adhere in greater numbers to first-generation silicone hydrogel lenses compared with the second-generation or hydroxyethyl methacrylate-based soft lenses. Microbial adhesion to silicone hydrogel lenses occurs and is associated with the production of corneal infiltrative events during lens wear.

Natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the Adriatic coast

Science.gov (United States)

Cozzolino, Davide; Greggio, Nicolas; Antonellini, Marco; Giambastiani, Beatrice Maria Sole

2017-08-01

This study characterizes the near-shore portion of the shallow coastal aquifer included in the Ravenna area (Northern Italy) with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity. The paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention. The influence that multiple natural and anthropogenic factors, such as land cover, local drainage network, and beach erosion have on the presence, size and evolution of the freshwater lenses in the aquifer is quantified and discussed. The methodology includes multiple seasonal monitoring and sampling campaigns of physical (water level, salinity, and temperature) and chemical (major cations and anions) groundwater parameters. Results indicate that freshwater lenses, where existing, are limited in thickness (about 1-2 m). Proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes. The pine forest land cover, that replaced the typical bush or sand cover, intensifies evapotranspiration reducing net infiltration and freshwater storage. The cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches, whereas a salinization process is ongoing in anthropogenic-impacted areas with strongly-fragmented dune systems. Currently, the thin freshwater lenses in the shallow Ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity. The dune-beach system, however, is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization, which in turn control the health of the whole coastal ecosystem.

Constraining the Intergalactic and Circumgalactic Media with Lyman-Alpha Absorption

Science.gov (United States)

Sorini, Daniele; Onorbe, Jose; Hennawi, Joseph F.; Lukic, Zarija

2018-01-01

Lyman-alpha (Ly-a) absorption features detected in quasar spectra in the redshift range 02Mpc, the simulations asymptotically match the observations, because the ΛCDM model successfully describes the ambient IGM. This represents a critical advantage of studying the mean absorption profile. However, significant differences between the simulations, and between simulations and observations are present on scales 20kpc-2Mpc, illustrating the challenges of accurately modeling and resolving galaxy formation physics. It is noteworthy that these differences are observed as far out as ~2Mpc, indicating that the `sphere-of-influence' of galaxies could extend to approximately ~20 times the halo virial radius (~100kpc). Current observations are very precise on these scales and can thus strongly discriminate between different galaxy formation models. I demonstrate that the Ly-a absorption profile is primarily sensitive to the underlying temperature-density relationship of diffuse gas around galaxies, and argue that it thus provides a fundamental test of galaxy formation models. With near-future high-precision observations of Ly-a absorption, the tools developed in my thesis set the stage for even stronger constraints on models of galaxy formation and cosmology.

Adhesion of Pseudomonas aeruginosa to orthokeratology and alignment lenses.

Science.gov (United States)

Choo, Jennifer D; Holden, Brien A; Papas, Eric B; Willcox, Mark D P

2009-02-01

To determine whether contact lenses designed for orthokeratology (OK) are colonized by greater numbers of bacteria compared with standard (alignment fitted) design rigid gas permeable lenses before and after lens wear. Eighteen 1-year-old cats were randomly fitted with an OK lens in one eye and an alignment fitted (AF) lens in the other eye. Both lenses were made in the same diameter and central thickness and of the same material. Two separate wearing periods of 2 weeks and 6 weeks were used. After each wearing period, lenses were soaked in Pseudomonas aeruginosa (6294 or 6206) for 10 min. The lenses were then reinserted onto their respective corneas for a wearing period of 16 hours after which lenses were collected and remaining adhered bacteria quantified. Unworn control lenses were also soaked and bacteria enumerated for comparison. There were no significant differences in the number of bacteria adherent to unworn AF and OK lenses. Analysis of lenses after wear showed OK lenses retained significantly higher numbers of viable bacteria than AF lenses in all studies. OK lenses retain more bacteria than AF rigid gas permeable lenses after bacteria-loaded overnight lens wear. This may increase the risk for an infection in OK patients should suitable conditions be present. Specific education on the cleaning of OK lenses is essential.

Performance Characterization of UV Science Cameras Developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

Science.gov (United States)

Champey, Patrick; Kobayashi, Ken; Winebarger, Amy; Cirtin, Jonathan; Hyde, David; Robertson, Bryan; Beabout, Brent; Beabout, Dyana; Stewart, Mike

2014-01-01

The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-alpha and to detect the Hanle effect in the line core. Due to the nature of Lyman-alpha polarization in the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. Coating the e2v CCD57-10 512x512 detectors with Lumogen-E coating allows for a relatively high (30%) quantum efficiency at the Lyman-$\\alpha$ line. The CLASP cameras were designed to operate with =10 e- /pixel/second dark current, = 25 e- read noise, a gain of 2.0 and =0.1% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

One Episode, Two Lenses

Science.gov (United States)

Drijvers, Paul; Godino, Juan D.; Font, Vicenc; Trouche, Luc

2013-01-01

A deep understanding of students' learning processes is one of the core challenges of research in mathematics education. To achieve this, different theoretical lenses are available. The question is how these different lenses compare and contrast, and how they can be coordinated and combined to provide a more comprehensive view on the topic of…

Solutions for care of silicone hydrogel lenses.

Science.gov (United States)

Willcox, Mark D P

2013-01-01

During wear of contact lenses on a daily wear basis, it is necessary to disinfect the lens overnight before reinserting the lens the next day. The ability of the solutions used for this to disinfect lenses and lens cases is important for safe lens wear. The literature on the disinfecting ability of multipurpose disinfecting solutions (MPDS) commonly used with silicone hydrogel lenses reported during the period 2000 to 2012 is reviewed, as this is the period of time during which these lenses have been commercially available. Particular emphasis is placed on the ability of disinfecting solutions to control colonization of lens cases by microbes and changes in composition and use of the solutions. In addition, the literature is reviewed on ways of minimizing lens case microbial contamination. Maintaining the hygiene of contact lenses and lens cases is important in minimizing various forms of corneal infiltrative events that occur during lens wear. Although lens case contamination is not associated with different lenses, it is determined by use of different MPDS. MPDS that allow more frequent or heavy contamination of cases by Gram-negative bacteria are associated with a higher incidence of corneal infiltrative events. MPDS are now available that contain dual disinfectants. Wiping lens cases with tissues or using lens cases that incorporate silver are associated with reductions in contamination in clinical trials. Similarly, using MPDS to rub and rinse lenses before disinfection may reduce levels of microbes on lenses. The MPDS also contain surfactants that help reduce deposition and denaturation of proteins on lenses. Improvements in MPDS formulations and hygiene practices may help to reduce the incidence of adverse events that are seen during use with silicone hydrogel lenses.

Adherence of Pseudomonas aeruginosa to contact lenses

International Nuclear Information System (INIS)

Miller, M.J.

1988-01-01

The purpose of this research was to examined the interactions of P. aeruginosa with hydrogel contact lenses and other substrata, and characterize adherence to lenses under various physiological and physicochemical conditions. Isolates adhered to polystyrene, glass, and hydrogel lenses. With certain lens types, radiolabeled cells showed decreased adherence with increasing water content of the lenses, however, this correlation with not found for all lenses. Adherence to rigid gas permeable lenses was markedly greater than adherence to hydrogels. Best adherence occurred near pH 7 and at a sodium chloride concentration of 50 mM. Passive adhesion of heat-killed cells to hydrogels was lower than the adherence obtained of viable cells. Adherence to hydrogels was enhanced by mucin, lactoferrin, lysozyme, IgA, bovine serum albumin, and a mixture of these macromolecules. Adherence to coated and uncoated lenses was greater with a daily-wear hydrogel when compared with an extended-wear hydrogel of similar polymer composition. Greater adherence was attributed to a higher concentration of adsorbed macromolecules on the 45% water-content lens in comparison to the 55% water-content lens

Constraints on small-scale cosmological fluctuations from SNe lensing dispersion

International Nuclear Information System (INIS)

Ben-Dayan, Ido; Takahashi, Ryuichi

2015-04-01

We provide predictions on small-scale cosmological density power spectrum from supernova lensing dispersion. Parameterizing the primordial power spectrum with running α and running of running β of the spectral index, we exclude large positive α and β parameters which induce too large lensing dispersions over current observational upper bound. We ran cosmological N-body simulations of collisionless dark matter particles to investigate non-linear evolution of the primordial power spectrum with positive running parameters. The initial small-scale enhancement of the power spectrum is largely erased when entering into the non-linear regime. For example, even if the linear power spectrum at k>10 hMpc -1 is enhanced by 1-2 orders of magnitude, the enhancement much decreases to a factor of 2-3 at late time (z≤1.5). Therefore, the lensing dispersion induced by the dark matter fluctuations weakly constrains the running parameters. When including baryon-cooling effects (which strongly enhance the small-scale clustering), the constraint is comparable or tighter than the PLANCK constraint, depending on the UV cut-off. Further investigations of the non-linear matter spectrum with baryonic processes is needed to reach a firm constraint.

Investigating the Lyman photon escape in local starburst galaxies with the Cosmic Origins Spectrograph ★

Science.gov (United States)

Hernandez, Svea; Leitherer, Claus; Boquien, Médéric; Buat, Véronique; Burgarella, Denis; Calzetti, Daniela; Noll, Stefan

2018-04-01

We present a study of 7 star-forming galaxies from the Cosmic Evolution Survey (COSMOS) observed with the Cosmic Origins Spectrograph (COS) on board the Hubble Space Telescope (HST). The galaxies are located at relatively low redshifts, z ˜0.3, with morphologies ranging from extended and disturbed to compact and smooth. To complement the HST observations we also analyze observations taken with the VIMOS spectrograph on the Very Large Telescope (VLT). In our galaxy sample we identify three objects with double peak Lyman-α profiles similar to those seen in Green Pea compact galaxies and measure peak separations of 655, 374, and 275 km s-1. We measure Lyman-α escape fractions with values ranging between 5-13%. Given the low flux levels in the individual COS exposures we apply a weighted stacking approach to obtain a single spectrum. From this COS combined spectrum we infer upper limits for the absolute and relative Lyman continuum escape fractions of f_abs(LyC) = 0.4^{+10.1}_{-0.4}% and f_res(LyC) = 1.7^{+15.2}_{-1.7}%, respectively. Finally, we find that most of these galaxies have moderate UV and optical SFRs (SFRs ≲ 10 M⊙ yr-1).

Microbial adherence to cosmetic contact lenses.

Science.gov (United States)

Chan, Ka Yin; Cho, Pauline; Boost, Maureen

2014-08-01

To investigate whether cosmetic contact lenses (CCL) with surface pigments affect microbial adherence. Fifteen brands of CCL were purchased from optical, non-optical retail outlets, and via the Internet. A standardized rub-off test was performed on each CCL (five lenses per brand) to confirm the location of the pigments. The rub-off test comprised gentle rubbing on the surfaces of each CCL with wetted cotton buds for a maximum of 20 rubs per surface. A new set of CCL (five lenses per brand) were incubated in Pseudomonas aeruginosa overnight. Viable counts of adhered bacteria were determined by the number of colony-forming units (CFU) on agar media on each lens. The adherence of P. aeruginosa as well as Staphylococcus aureus and Serratia marcescens to three brands of CCL (A-C) (five lenses per brand) were also compared to their adherences on their clear counterparts. Only two of the 15 brands of CCL tested (brands B and C) had pigments that did not detach with the rub-off test. The remaining 13 brands of CCL all failed the rub-off test and these lenses showed higher P. aeruginosa adherence (8.7 × 10(5)-1.9 × 10(6) CFU/lens). Brands B and C lenses showed at least six times less bacterial adhesion than the other 13 brands. Compared to their clear counterparts, bacterial adherence to brands B and C lenses did not differ significantly, whereas brand A lenses showed significantly higher adherence. Surface pigments on CCL resulted in significantly higher bacterial adherence. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Evidence for Black Hole Growth in Local Analogs to Lyman Break Galaxies

Science.gov (United States)

Jia, Jianjun; Ptak, Andrew; Heckman, Timothy M.; Overzier, Roderik A.; Hornschemeier, Ann; LaMassa, Stephanie M.

2011-01-01

We have used XMM-Newton to observe six Lyman break analogs (LBAs): members of the rare population of local galaxies that have properties that are very similar to distant Lyman break galaxies. Our six targets were specifically selected because they have optical emission-line properties that are intermediate between starbursts and Type 2 (obscured) active galactic nuclei (AGNs). Our new X-ray data provide an important diagnostic of the presence of an AGN. We find X-ray luminosities of order 10(sup 42) erg per second and ratios of X-ray to far-IR lummositles that are higher than values in pure starburst galaxies by factors ranging from approximately 3 to 30. This strongly suggests the presence of an AGN in at least some of the galaxies. The ratios of the luminosities of the hard (2-10 keV) X-ray to [O III] emission line are low by about an order of magnitude compared with Type 1 AGN, but are consistent with the broad range seen in Type 2 AGN. Either the AGN hard X-rays are significantly obscured or the [O III] emission is dominated by the starburst. We searched for an iron emission line at approximately 6.4 ke V, which is a key feature of obscured AGNs, but only detected emission at the approximately 2sigma level. Finally, we find that the ratios of the mid-infrared (24 micrometer) continuum to [O III]lambda 5007 luminosities in these LBAs are higher than the values for Type 2 AGN by an average of 0.8 dex. Combining all these clues, we conclude that an AGN is likely to be present, but that the bolometric luminosity is produced primarily by an intense starburst. If these black holes are radiating at the Eddington limit, their masses would lie in the range of 10(sup 5) - 10(sup 6) solar mass. These objects may offer ideal local laboratories to investigate the processes by which black holes grew in the early universe.

A MAGNIFIED GLANCE INTO THE DARK SECTOR: PROBING COSMOLOGICAL MODELS WITH STRONG LENSING IN A1689

International Nuclear Information System (INIS)

Magaña, Juan; Motta, V.; Cárdenas, Victor H.; Verdugo, T.; Jullo, Eric

2015-01-01

In this paper we constrain four alternative models to the late cosmic acceleration in the universe: Chevallier–Polarski–Linder (CPL), interacting dark energy (IDE), Ricci holographic dark energy (HDE), and modified polytropic Cardassian (MPC). Strong lensing (SL) images of background galaxies produced by the galaxy cluster Abell 1689 are used to test these models. To perform this analysis we modify the LENSTOOL lens modeling code. The value added by this probe is compared with other complementary probes: Type Ia supernovae (SN Ia), baryon acoustic oscillations (BAO), and cosmic microwave background (CMB). We found that the CPL constraints obtained for the SL data are consistent with those estimated using the other probes. The IDE constraints are consistent with the complementary bounds only if large errors in the SL measurements are considered. The Ricci HDE and MPC constraints are weak, but they are similar to the BAO, SN Ia, and CMB estimations. We also compute the figure of merit as a tool to quantify the goodness of fit of the data. Our results suggest that the SL method provides statistically significant constraints on the CPL parameters but is weak for those of the other models. Finally, we show that the use of the SL measurements in galaxy clusters is a promising and powerful technique to constrain cosmological models. The advantage of this method is that cosmological parameters are estimated by modeling the SL features for each underlying cosmology. These estimations could be further improved by SL constraints coming from other galaxy clusters

Response approach to the squeezed-limit bispectrum: application to the correlation of quasar and Lyman-α forest power spectrum

Energy Technology Data Exchange (ETDEWEB)

Chiang, Chi-Ting [C.N. Yang Institute for Theoretical Physics, Stony Brook University, Stony Brook, NY 11794 (United States); Cieplak, Agnieszka M.; Slosar, Anže [Brookhaven National Laboratory, Blgd 510, Upton, NY 11375 (United States); Schmidt, Fabian, E-mail: chi-ting.chiang@stonybrook.edu, E-mail: acieplak@bnl.gov, E-mail: fabians@mpa-garching.mpg.de, E-mail: anze@bnl.gov [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany)

2017-06-01

The squeezed-limit bispectrum, which is generated by nonlinear gravitational evolution as well as inflationary physics, measures the correlation of three wavenumbers, in the configuration where one wavenumber is much smaller than the other two. Since the squeezed-limit bispectrum encodes the impact of a large-scale fluctuation on the small-scale power spectrum, it can be understood as how the small-scale power spectrum ''responds'' to the large-scale fluctuation. Viewed in this way, the squeezed-limit bispectrum can be calculated using the response approach even in the cases which do not submit to perturbative treatment. To illustrate this point, we apply this approach to the cross-correlation between the large-scale quasar density field and small-scale Lyman-α forest flux power spectrum. In particular, using separate universe simulations which implement changes in the large-scale density, velocity gradient, and primordial power spectrum amplitude, we measure how the Lyman-α forest flux power spectrum responds to the local, long-wavelength quasar overdensity, and equivalently their squeezed-limit bispectrum. We perform a Fisher forecast for the ability of future experiments to constrain local non-Gaussianity using the bispectrum of quasars and the Lyman-α forest. Combining with quasar and Lyman-α forest power spectra to constrain the biases, we find that for DESI the expected 1−σ constraint is err[ f {sub NL}]∼60. Ability for DESI to measure f {sub NL} through this channel is limited primarily by the aliasing and instrumental noise of the Lyman-α forest flux power spectrum. The combination of response approach and separate universe simulations provides a novel technique to explore the constraints from the squeezed-limit bispectrum between different observables.

Photometry of High-Redshift Gravitationally Lensed Type Ia Supernovae

Science.gov (United States)

Haynie, Annastasia

2018-01-01

Out of more than 1100 well-identified Type Ia Supernovae, only roughly 10 of them are at z> 1.5. High redshift supernovae are hard to detect but this is made easier by taking advantage of the effects of gravitational lensing, which magnifies objects in the background field of massive galaxy clusters. Supernova Nebra (z= ~1.8), among others, was discovered during observations taken as part of the RELICS survey, which focused on fields of view that experience strong gravitational lensing effects. SN Nebra, which sits behind galaxy cluster Abell 1763, is magnified and therefore appears closer and easier to see than with HST alone. Studying high-redshift supernovae like SN Nebra is an important step towards creating cosmological models that accurately describe the behavior of dark energy in the early Universe. Recent efforts have been focused on improving photometry and the building and fitting of preliminary light curves.

Determination of magnetic field direction in tokamaks from laser-induced Lyman-α fluorescence

International Nuclear Information System (INIS)

Voslamber, D.

1988-04-01

Resonant laser scattering in the Lyman-α line of hydrogen is investigated as a possible tool for measuring the magnetic field direction in tokamak plasmas. The method is based on the depolarisation-dependence of the scattering process. Limitations arising from depolarising collisions are studied in detail by employing a previously developed theory for the collisional redistribution of light. An error analysis is performed to derive the expected experimental precision under various plasma conditions and for laser energies ranging between 1 micronJ and 10 mJ. This analysis also includes the measurement of neutral hydrogen densities. It is shown that with presently available laser powers application of the method would be restricted to the border regions of the plasma. Application to the central regions would require further developments in laser technology, especially with regard to higher powers at the wavelength of Lyman-α and (or) to fast repetition rates

Intraocular pressure measurement with the noncontact tonometer through soft contact lenses.

Science.gov (United States)

Liu, Yi-Chun; Huang, Jehn-Yu; Wang, I-Jong; Hu, Fung-Rong; Hou, Yu-Chih

2011-03-01

To assess the accuracy of measuring intraocular pressure (IOP) through a soft contact lens (SCL) with different refractive powers using a noncontact tonometer (NCT). Thirty-two healthy adult volunteers free of glaucoma or corneal disease participated in this study. IOP was measured in the right eyes without SCLs and with different lens powers, from -3.0 to -12.0 D as measured by NCT. IOP of the left eyes was also measured, as an internal control. Corneal curvature was measured in both eyes using an autokeratometer. Sixteen volunteers wore one brand of SCL (group A) and the other 16 wore a different brand, with 2 different curvatures (groups B and C). Statistical data were analyzed by SPSS using the Wilcoxon signed rank test for comparison of IOP readings and multiple linear regression analysis for the relationship among power of contact lenses, corneal power, and difference in IOP measurements. The difference in mean IOP between eyes without lenses and those with lenses was statistically significant in lens with -6.0 D and below in all 3 groups. The decrease in IOP significantly correlated with the refractive power of contact lenses in all 3 groups. The difference in IOP measurements was influenced by the mean K in group A but not in group B or C. There was no statistically significant difference in the IOP measurements in the left eyes or in the mean K between the right and left eyes. IOP measurement through myopic SCLs by NCT may be inaccurate and tends toward underestimation, especially in high myopic lenses. A strong relationship exists between IOP reduction and myopic lens power.

Lens Model and Time Delay Predictions for the Sextuply Lensed Quasar SDSS J2222+2745*

Science.gov (United States)

Sharon, Keren; Bayliss, Matthew B.; Dahle, Hakon; Florian, Michael K.; Gladders, Michael D.; Johnson, Traci L.; Paterno-Mahler, Rachel; Rigby, Jane R.; Whitaker, Katherine E.; Wuyts, Eva

2017-01-01

SDSS J2222+2745 is a galaxy cluster at z = 0.49, strongly lensing a quasar at z = 2.805 into six widely separated images. In recent Hubble Space Telescope imaging of the field, we identify additional multiply lensed galaxies and confirm the sixth quasar image that was identified by Dahle et al. We used the Gemini-North telescope to measure a spectroscopic redshift of z = 4.56 of one of the lensed galaxies. These data are used to refine the lens model of SDSS J2222+2745, compute the time delay and magnifications of the lensed quasar images, and reconstruct the source image of the quasar host and a lensed galaxy at z = 2.3. This galaxy also appears in absorption in our Gemini spectra of the lensed quasar, at a projected distance of 34 kpc. Our model is in agreement with the recent time delay measurements of Dahle et al., who found T(sub AB) = 47.7 +/- 6.0 days and T(sub AC) = 722 +/- 24 days. We use the observed time delays to further constrain the model, and find that the model-predicted time delays of the three faint images of the quasar are T(sub AD) = 502+/- 68 days, T( sub AE) = 611 +/- 75 days, and T(sub AF) = 415 +/- 72 days. We have initiated a follow-up campaign to measure these time delays with Gemini North. Finally, we present initial results from an X-ray monitoring program with Swift, indicating the presence of hard X-ray emission from the lensed quasar, as well as extended X-ray emission from the cluster itself, which is consistent with the lensing mass measurement and the cluster velocity dispersion.

LENS MODEL AND TIME DELAY PREDICTIONS FOR THE SEXTUPLY LENSED QUASAR SDSS J2222+2745

Energy Technology Data Exchange (ETDEWEB)

Sharon, Keren; Johnson, Traci L.; Paterno-Mahler, Rachel [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Bayliss, Matthew B. [Colby College, 5800 Mayflower Hill, Waterville, 04901, Maine (United States); Dahle, Håkon [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Florian, Michael K.; Gladders, Michael D. [Department of Astronomy and Astrophysics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Rigby, Jane R. [Astrophysics Science Division, Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Whitaker, Katherine E. [Department of Astronomy, University of Massachusetts-Amherst, Amherst, MA 01003 (United States); Wuyts, Eva, E-mail: kerens@umich.edu [Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, D-85741 Garching (Germany)

2017-01-20

SDSS J2222+2745 is a galaxy cluster at z = 0.49, strongly lensing a quasar at z = 2.805 into six widely separated images. In recent Hubble Space Telescope imaging of the field, we identify additional multiply lensed galaxies and confirm the sixth quasar image that was identified by Dahle et al. We used the Gemini-North telescope to measure a spectroscopic redshift of z = 4.56 of one of the lensed galaxies. These data are used to refine the lens model of SDSS J2222+2745, compute the time delay and magnifications of the lensed quasar images, and reconstruct the source image of the quasar host and a lensed galaxy at z = 2.3. This galaxy also appears in absorption in our Gemini spectra of the lensed quasar, at a projected distance of 34 kpc. Our model is in agreement with the recent time delay measurements of Dahle et al., who found τ {sub AB} = 47.7 ± 6.0 days and τ {sub AC} = −722 ± 24 days. We use the observed time delays to further constrain the model, and find that the model-predicted time delays of the three faint images of the quasar are τ {sub AD} = 502 ± 68 days, τ {sub AE} = 611 ± 75 days, and τ {sub AF} = 415 ± 72 days. We have initiated a follow-up campaign to measure these time delays with Gemini North. Finally, we present initial results from an X-ray monitoring program with Swift , indicating the presence of hard X-ray emission from the lensed quasar, as well as extended X-ray emission from the cluster itself, which is consistent with the lensing mass measurement and the cluster velocity dispersion.

Cross-correlation of weak lensing and gamma rays: implications for the nature of dark matter

Science.gov (United States)

Tröster, Tilman; Camera, Stefano; Fornasa, Mattia; Regis, Marco; van Waerbeke, Ludovic; Harnois-Déraps, Joachim; Ando, Shin'ichiro; Bilicki, Maciej; Erben, Thomas; Fornengo, Nicolao; Heymans, Catherine; Hildebrandt, Hendrik; Hoekstra, Henk; Kuijken, Konrad; Viola, Massimo

2017-05-01

We measure the cross-correlation between Fermi gamma-ray photons and over 1000 deg2 of weak lensing data from the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), the Red Cluster Sequence Lensing Survey (RCSLenS), and the Kilo Degree Survey (KiDS). We present the first measurement of tomographic weak lensing cross-correlations and the first application of spectral binning to cross-correlations between gamma rays and weak lensing. The measurements are performed using an angular power spectrum estimator while the covariance is estimated using an analytical prescription. We verify the accuracy of our covariance estimate by comparing it to two internal covariance estimators. Based on the non-detection of a cross-correlation signal, we derive constraints on weakly interacting massive particle (WIMP) dark matter. We compute exclusion limits on the dark matter annihilation cross-section , decay rate Γdec and particle mass mDM. We find that in the absence of a cross-correlation signal, tomography does not significantly improve the constraining power of the analysis. Assuming a strong contribution to the gamma-ray flux due to small-scale clustering of dark matter and accounting for known astrophysical sources of gamma rays, we exclude the thermal relic cross-section for particle masses of mDM ≲ 20 GeV.

Gauge-invariant formalism of cosmological weak lensing

Science.gov (United States)

Yoo, Jaiyul; Grimm, Nastassia; Mitsou, Ermis; Amara, Adam; Refregier, Alexandre

2018-04-01

We present the gauge-invariant formalism of cosmological weak lensing, accounting for all the relativistic effects due to the scalar, vector, and tensor perturbations at the linear order. While the light propagation is fully described by the geodesic equation, the relation of the photon wavevector to the physical quantities requires the specification of the frames, where they are defined. By constructing the local tetrad bases at the observer and the source positions, we clarify the relation of the weak lensing observables such as the convergence, the shear, and the rotation to the physical size and shape defined in the source rest-frame and the observed angle and redshift measured in the observer rest-frame. Compared to the standard lensing formalism, additional relativistic effects contribute to all the lensing observables. We explicitly verify the gauge-invariance of the lensing observables and compare our results to previous work. In particular, we demonstrate that even in the presence of the vector and tensor perturbations, the physical rotation of the lensing observables vanishes at the linear order, while the tetrad basis rotates along the light propagation compared to a FRW coordinate. Though the latter is often used as a probe of primordial gravitational waves, the rotation of the tetrad basis is indeed not a physical observable. We further clarify its relation to the E-B decomposition in weak lensing. Our formalism provides a transparent and comprehensive perspective of cosmological weak lensing.

Precision cosmology from future lensed gravitational wave and electromagnetic signals.

Science.gov (United States)

Liao, Kai; Fan, Xi-Long; Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong

2017-10-27

The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10 4 -10 5 gravitational wave detections per year, 50-100 of which will be lensed. Here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. We demonstrate that just 10 such systems can provide a Hubble constant uncertainty of 0.68% for a flat lambda cold dark matter universe in the era of third-generation ground-based detectors.

Weak lensing and dark energy

International Nuclear Information System (INIS)

Huterer, Dragan

2002-01-01

We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy

High Resolution Studies Of Lensed z ∼ 2 Galaxies: Kinematics And Metal Gradients

Science.gov (United States)

Leethochawalit, Nicha

2016-09-01

We use the OSIRIS integral field unit (IFU) spectograph to secure spatially-resolved strong emission lines of 15 gravitationally-lensed star-forming galaxies at redshift z ∼ 2. With the aid of gravitational lensing and Keck laser-assisted adaptive optics, the spatial resolution of these sub-luminous galaxies is at a few hundred parsecs. First, we demonstrate that high spatial resolution is crucial in diagnosing the kinematic properties and dynamical maturity of z ∼ 2 galaxies. We observe a significantly lower fraction of rotationally-supported systems than what has been claimed in lower spatial resolution surveys. Second, we find a much larger fraction of z ∼ 2 galaxies with weak metallicity gradients, contrary to the simple picture suggested by earlier studies that well-ordered rotation develops concurrently with established steep metal gradients in all but merging systems. Comparing our observations with the predictions of hydronamical simulations, strong feedback is likely to play a key role in flattening metal gradients in early star-forming galaxies.

Detection of 3-Minute Oscillations in Full-Disk Lyman-alpha Emission During A Solar Flare

Science.gov (United States)

Milligan, R. O.; Ireland, J.; Fleck, B.; Hudson, H. S.; Fletcher, L.; Dennis, B. R.

2017-12-01

We report the detection of chromospheric 3-minute oscillations in disk-integrated EUV irradiance observations during a solar flare. A wavelet analysis of detrended Lyman-alpha (from GOES/EUVS) and Lyman continuum (from SDO/EVE) emission from the 2011 February 15 X-class flare revealed a 3-minute period present during the flare's main phase. The formation temperature of this emission locates this radiation to the flare's chromospheric footpoints, and similar behaviour is found in the SDO/AIA 1600A and 1700A channels, which are dominated by chromospheric continuum. The implication is that the chromosphere responds dynamically at its acoustic cutoff frequency to an impulsive injection of energy. Since the 3-minute period was not found at hard X-ray energies (50-100 keV) in RHESSI data we can state that this 3-minute oscillation does not depend on the rate of energization of, or energy deposition by, non-thermal electrons. However, a second period of 120 s found in both hard X-ray and chromospheric emission is consistent with episodic electron energization on 2-minute timescales. Our finding on the 3-minute oscillation suggests that chromospheric mechanical energy should be included in the flare energy budget, and the fluctuations in the Lyman-alpha line may influence the composition and dynamics of planetary atmospheres during periods of high activity.

Instrumental systematics and weak gravitational lensing

International Nuclear Information System (INIS)

Mandelbaum, R.

2015-01-01

We present a pedagogical review of the weak gravitational lensing measurement process and its connection to major scientific questions such as dark matter and dark energy. Then we describe common ways of parametrizing systematic errors and understanding how they affect weak lensing measurements. Finally, we discuss several instrumental systematics and how they fit into this context, and conclude with some future perspective on how progress can be made in understanding the impact of instrumental systematics on weak lensing measurements

Soft-contact-lenses-induced complications

Directory of Open Access Journals (Sweden)

Suvajac Gordana

2008-01-01

Full Text Available Background/Aim. Soft contact lenses occupy significant place in ophthalmology, both in the correction of refraction anomalies and in the treatment of many eye diseases. The number of patients that wear soft contact lenses for the purpose of correcting ametropia is constantly increasing. Due to the increasing number of wearers, the percentage of complications that can lead to serious eye damage and serious vision loss is also increasing. The aim of this study was to point out the most common complications related to soft contact lens use. Methods. In the period from 1995−2004 this prospective study included 510 patients wearing soft contact lenses for correcting ametropia. None of the patients wore contact lenses before and none suffered from any system or local diseases that could affected the development of eventual complications. The study took seven years with the patients who wore conventional lenses and three years with those who wore replacement contact lenses. All the necessary ophthalmologic examinations were done (visual acuity, refractokeratometry, the quantity of tear film, biomicroscopic examination of anterior eye segment. All the complications were filmed by video camera. Results. Of all the patients, 19 had blepharitis, 73 suffered from “dry eye”, 57 had conjunctival hyperemia, 12 had conjunctivitis, 34 had gigantopapillary conjunctivitis (GPC, 93 had punctiform epitheliopathy, 20 had corneal infiltration, one patient had keratitis, 91 had corneal vascularisation, and 95 patients had corneal deposits. Conclusion. Both the type and frequency of complications related to soft contact lens use in our group of patients, proved to be significant. Some of this complications (keratitis can significantly damage vision and lead to loss of vision and sometimes can require operative treatment.

Deep convolutional neural networks as strong gravitational lens detectors

Science.gov (United States)

Schaefer, C.; Geiger, M.; Kuntzer, T.; Kneib, J.-P.

2018-03-01

Context. Future large-scale surveys with high-resolution imaging will provide us with approximately 105 new strong galaxy-scale lenses. These strong-lensing systems will be contained in large data amounts, however, which are beyond the capacity of human experts to visually classify in an unbiased way. Aim. We present a new strong gravitational lens finder based on convolutional neural networks (CNNs). The method was applied to the strong-lensing challenge organized by the Bologna Lens Factory. It achieved first and third place, respectively, on the space-based data set and the ground-based data set. The goal was to find a fully automated lens finder for ground-based and space-based surveys that minimizes human inspection. Methods: We compared the results of our CNN architecture and three new variations ("invariant" "views" and "residual") on the simulated data of the challenge. Each method was trained separately five times on 17 000 simulated images, cross-validated using 3000 images, and then applied to a test set with 100 000 images. We used two different metrics for evaluation, the area under the receiver operating characteristic curve (AUC) score, and the recall with no false positive (Recall0FP). Results: For ground-based data, our best method achieved an AUC score of 0.977 and a Recall0FP of 0.50. For space-based data, our best method achieved an AUC score of 0.940 and a Recall0FP of 0.32. Adding dihedral invariance to the CNN architecture diminished the overall score on space-based data, but achieved a higher no-contamination recall. We found that using committees of five CNNs produced the best recall at zero contamination and consistently scored better AUC than a single CNN. Conclusions: We found that for every variation of our CNN lensfinder, we achieved AUC scores close to 1 within 6%. A deeper network did not outperform simpler CNN models either. This indicates that more complex networks are not needed to model the simulated lenses. To verify this, more

KiDS-450: tomographic cross-correlation of galaxy shear with Planck lensing

Science.gov (United States)

Harnois-Déraps, Joachim; Tröster, Tilman; Chisari, Nora Elisa; Heymans, Catherine; van Waerbeke, Ludovic; Asgari, Marika; Bilicki, Maciej; Choi, Ami; Erben, Thomas; Hildebrandt, Hendrik; Hoekstra, Henk; Joudaki, Shahab; Kuijken, Konrad; Merten, Julian; Miller, Lance; Robertson, Naomi; Schneider, Peter; Viola, Massimo

2017-10-01

We present the tomographic cross-correlation between galaxy lensing measured in the Kilo Degree Survey (KiDS-450) with overlapping lensing measurements of the cosmic microwave background (CMB), as detected by Planck 2015. We compare our joint probe measurement to the theoretical expectation for a flat Λ cold dark matter cosmology, assuming the best-fitting cosmological parameters from the KiDS-450 cosmic shear and Planck CMB analyses. We find that our results are consistent within 1σ with the KiDS-450 cosmology, with an amplitude re-scaling parameter AKiDS = 0.86 ± 0.19. Adopting a Planck cosmology, we find our results are consistent within 2σ, with APlanck = 0.68 ± 0.15. We show that the agreement is improved in both cases when the contamination to the signal by intrinsic galaxy alignments is accounted for, increasing A by ∼0.1. This is the first tomographic analysis of the galaxy lensing - CMB lensing cross-correlation signal, and is based on five photometric redshift bins. We use this measurement as an independent validation of the multiplicative shear calibration and of the calibrated source redshift distribution at high redshifts. We find that constraints on these two quantities are strongly correlated when obtained from this technique, which should therefore not be considered as a stand-alone competitive calibration tool.

Weakly oval electron lense

International Nuclear Information System (INIS)

Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.

2001-01-01

The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system

Lenses matching of compound eye for target positioning

Science.gov (United States)

Guo, Fang; Zheng, Yan Pei; Wang, Keyi

2012-10-01

Compound eye, as a new imaging method with multi-lens for a large field of view, could complete target positioning and detection fastly, especially at close range. Therefore it could be applicated in the fields of military and medical treatment and aviation with vast market potential and development prospect. Yet the compound eye imaging method designed use three layer construction of multiple lens array arranged in a curved surface and refractive lens and imaging sensor of CMOS. In order to simplify process structure and increase the imaging area of every sub-eye, the imaging area of every eye is coved with the whole CMOS. Therefore, for several imaging point of one target, the corresponding lens of every imaging point is unkonown, and thus to identify. So an algorithm was put forward. Firstly, according to the Regular Geometry relationship of several adjacent lenses, data organization of seven lenses with a main lens was built. Subsequently, by the data organization, when one target was caught by several unknown lenses, we search every combined type of the received lenses. And for every combined type, two lenses were selected to combine and were used to calculate one three-dimensional (3D) coordinate of the target. If the 3D coordinates are same to the some combine type of the lenses numbers, in theory, the lenses and the imaging points are matched. So according to error of the 3D coordinates is calculated by the different seven lenses numbers combines, the unknown lenses could be distinguished. The experimental results show that the presented algorithm is feasible and can complete matching task for imaging points and corresponding lenses.

High-speed optical signal processing using time lenses

DEFF Research Database (Denmark)

Galili, Michael; Hu, Hao; Guan, Pengyu

2015-01-01

This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

Chitah: Strong-gravitational-lens hunter in imaging surveys

Energy Technology Data Exchange (ETDEWEB)

Chan, James H. H.; Suyu, Sherry H.; Chiueh, Tzihong; More, Anupreeta; Marshall, Philip J.; Coupon, Jean; Oguri, Masamune; Price, Paul

2015-07-07

Strong gravitationally lensed quasars provide powerful means to study galaxy evolution and cosmology. Current and upcoming imaging surveys will contain thousands of new lensed quasars, augmenting the existing sample by at least two orders of magnitude. To find such lens systems, we built a robot, Chitah, that hunts for lensed quasars by modeling the configuration of the multiple quasar images. Specifically, given an image of an object that might be a lensed quasar, Chitah first disentangles the light from the supposed lens galaxy and the light from the multiple quasar images based on color information. A simple rule is designed to categorize the given object as a potential four-image (quad) or two-image (double) lensed quasar system. The configuration of the identified quasar images is subsequently modeled to classify whether the object is a lensed quasar system. We test the performance of Chitah using simulated lens systems based on the Canada–France–Hawaii Telescope Legacy Survey. For bright quads with large image separations (with Einstein radius ${r}_{\\mathrm{ein}}\\gt 1\\buildrel{\\prime\\prime}\\over{.} 1$) simulated using Gaussian point-spread functions, a high true-positive rate (TPR) of $\\sim 90\\%$ and a low false-positive rate of $\\sim 3\\%$ show that this is a promising approach to search for new lens systems. We obtain high TPR for lens systems with ${r}_{\\mathrm{ein}}\\gtrsim 0\\buildrel{\\prime\\prime}\\over{.} 5$, so the performance of Chitah is set by the seeing. We further feed a known gravitational lens system, COSMOS 5921+0638, to Chitah, and demonstrate that Chitah is able to classify this real gravitational lens system successfully. Our newly built Chitah is omnivorous and can hunt in any ground-based imaging surveys.

Factors influencing bacterial adhesion to contact lenses.

Science.gov (United States)

Dutta, Debarun; Cole, Nerida; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The adhesion of this strain reaches maximum numbers within 1h in most in vitro studies and a biofilm has generally formed within 24 h of cells adhering to the lens surface. Physical and chemical properties of contact lens material affect bacterial adhesion. The water content of hydroxyethylmethacrylate (HEMA)-based lenses and their iconicity affect the ability of bacteria to adhere. The higher hydrophobicity of silicone hydrogel lenses compared to HEMA-based lenses has been implicated in the higher numbers of bacteria that can adhere to their surfaces. Lens wear has different effects on bacterial adhesion, partly due to differences between wearers, responses of bacterial strains and the ability of certain tear film proteins when bound to a lens surface to kill certain types of bacteria.

Dynamics of Fermat potentials in nonperturbative gravitational lensing

International Nuclear Information System (INIS)

Frittelli, Simonetta; Newman, Ezra T.

2002-01-01

We present a framework, based on the null-surface formulation of general relativity, for discussing the dynamics of Fermat potentials for gravitational lensing in a generic situation without approximations of any kind. Additionally, we derive two lens equations: one for the case of thick compact lenses and the other one for lensing by gravitational waves. These equations in principle generalize the astrophysical scheme for lensing by removing the thin-lens approximation while retaining the weak fields

Dark energy and curvature from a future baryonic acoustic oscillation survey using the Lyman-α forest

International Nuclear Information System (INIS)

McDonald, Patrick; Eisenstein, Daniel J.

2007-01-01

We explore the requirements for a Lyman-α forest survey designed to measure the angular diameter distance and Hubble parameter at 2 or approx. 250 spectrograph is sufficient to measure both the radial and transverse oscillation scales to 1.4% from the Lyα forest (or better, if fainter magnitudes and possibly Lyman-break galaxies can be used). At fixed integration time and in the sky-noise-dominated limit, a wider, noisier survey is generally more efficient; the only fundamental upper limit on noise being the need to identify a quasar and find a redshift. Because the Lyα forest is much closer to linear and generally better understood than galaxies, systematic errors are even less likely to be a problem

Nanofocusing Parabolic Refractive X-Ray Lenses

International Nuclear Information System (INIS)

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A. S.; Snigirev, A.; Snigireva, I.

2004-01-01

Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100nm range even at short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 330nm by 110nm at 25keV in a distance of 41.8m from the synchrotron radiation source. First microdiffraction and fluorescence microtomography experiments were carried out with these lenses. Using diamond as lens material, microbeams with lateral size down to 20nm and below are conceivable in the energy range from 10 to 100keV

Do swimming goggles limit microbial contamination of contact lenses?

Science.gov (United States)

Wu, Yvonne T; Tran, Jess; Truong, Michelle; Harmis, Najat; Zhu, Hua; Stapleton, Fiona

2011-04-01

Wearing goggles over contact lenses while swimming is often recommended by eye care professionals. Limited data are available to assess this recommendation. The purpose of this study was to examine whether wearing goggles while swimming limits bacterial colonization on contact lenses and whether the type of lens worn affects contamination rates. Twenty-three subjects underwent two swimming sessions at an ocean (salt water) pool (Maroubra beach Rock Pool, Sydney, Australia). Silicone hydrogel (Ciba Focus Night and Day) or hydrogel lenses (Ciba Focus Daily) were inserted into subjects' eyes before 30 min of swimming sessions, and subjects used modified goggles to mimic goggled and non-goggled conditions. At the end of each session, lenses were collected for microbial investigation. Viable bacterial colonies were classified as gram positive and gram negative and enumerated. The level of bacterial colonization on contact lenses between goggled and non-goggled conditions and between the two lens materials were compared. The range of colony forming units recovered from goggled lenses were 0 to 930 compared with 0 to 1210 on non-goggled lenses. The majority of subjects (16/23) had more microorganisms in the non-goggled condition than when wearing goggles (p = 0.03). Gram negative organisms were found in three non-goggled lenses. No significant difference was shown in the number of bacteria isolated from silicone hydrogel and hydrogel lenses (p > 0.6) irrespective of wearing goggles. Water samples had consistently higher numbers of bacterial counts than those adhered to the lenses; however, no association was found between the number of bacteria in the water sample and those found on the contact lenses. Consistently, fewer bacterial colonies were found on the goggled contact lens, thus suggesting goggles offer some protection against bacterial colonization of contact lenses while swimming. These data would support the recommendation encouraging lens wearers to use goggles

RELICS: A Candidate Galaxy Arc at z~10 and Other Brightly Lensed z>6 Galaxies

Science.gov (United States)

Salmon, Brett; Coe, Dan; Bradley, Larry; Bradac, Marusa; Huang, Kuang-Han; Oesch, Pascal; Brammer, Gabriel; Stark, Daniel P.; Sharon, Keren; Trenti, Michele; Avila, Roberto J.; Ogaz, Sara; Acebron, Ana; Andrade-Santos, Felipe; Carrasco, Daniela; Cerny, Catherine; Cibirka, Nathália; Dawson, William; Frye, Brenda; Hoag, Austin; Jones, Christine; Mainali, Ramesh; Ouchi, Masami; Paterno-Mahler, Rachel; Rodney, Steven; Umetsu, Keiichi; Zitrin, Adi; RELICS

2018-01-01

Massive foreground galaxy clusters magnify and distort the light of objects behind them, permitting a view into both the extremely distant and intrinsically faint galaxy populations. We present here some of the most brightly lensed z>6 galaxy candidates known from the Reionization Lensing Cluster Survey (RELICS) and the discovery of a particularly fortuitous z~10 galaxy candidate which has been arced by the effects of strong gravitational lensing. The z~10 candidate has a lensed H-band magnitude of 25.8 AB mag and a high lensing magnification (~4-7). The inferred upper limits on the stellar mass (log [M_star /M_Sun]=9.5) and star formation rate (log [SFR/(M_Sun/yr)]=1.5) indicate that this candidate is a typical star-forming galaxy on the z>6 SFR-M_star relation. We rule out the only low-z solution as unphysical based on the required stellar mass, dust attenuation, size, and [OIII] EW needed for a z~2 SED to match the data. Finally, we reconstruct the source-plane image and estimate the candidate's physical size at z~10, finding a half-light radius of r_e 9 candidates. While the James Webb Space Telescope will detect z>10 with ease, this rare candidate offers the potential for unprecedented spatial resolution less than 500 Myr after the Big Bang.

ABSORPTION-LINE SPECTROSCOPY OF GRAVITATIONALLY LENSED GALAXIES: FURTHER CONSTRAINTS ON THE ESCAPE FRACTION OF IONIZING PHOTONS AT HIGH REDSHIFT

Energy Technology Data Exchange (ETDEWEB)

Leethochawalit, Nicha; Ellis, Richard S.; Zitrin, Adi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, MS 249-17, Pasadena, CA 91125 (United States); Jones, Tucker A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Stark, Daniel P. [Department of Astronomy, University of Arizona, Tucson, AZ 85721 (United States)

2016-11-10

The fraction of ionizing photons escaping from high-redshift star-forming galaxies is a key obstacle in evaluating whether galaxies were the primary agents of cosmic reionization. We previously proposed using the covering fraction of low-ionization gas, measured via deep absorption-line spectroscopy, as a proxy. We now present a significant update, sampling seven gravitationally lensed sources at 4 < z < 5. We show that the absorbing gas in our sources is spatially inhomogeneous, with a median covering fraction of 66%. Correcting for reddening according to a dust-in-cloud model, this implies an estimated absolute escape fraction of ≃19% ± 6%. With possible biases and uncertainties, collectively we find that the average escape fraction could be reduced to no less than 11%, excluding the effect of spatial variations. For one of our lensed sources, we have sufficient signal-to-noise ratio to demonstrate the presence of such spatial variations and scatter in its dependence on the Ly α equivalent width, consistent with recent simulations. If this source is typical, our lower limit to the escape fraction could be reduced by a further factor ≃2. Across our sample, we find a modest anticorrelation between the inferred escape fraction and the local star formation rate, consistent with a time delay between a burst and leaking Lyman continuum photons. Our analysis demonstrates considerable variations in the escape fraction, consistent with being governed by the small-scale behavior of star-forming regions, whose activities fluctuate over short timescales. This supports the suggestion that the escape fraction may increase toward the reionization era when star formation becomes more energetic and burst-like.

A Strong-Lens Survey in AEGIS: the influence of large scalestructure

Energy Technology Data Exchange (ETDEWEB)

Moustakas, Leonidas A.; Marshall, Phil; Newman, Jeffrey A.; Coil,Alison L.; Cooper, Michael C.; Davis, Marc; Fassnacht, Christopher D.; Guhathakurta, Puragra; Hopkins, Andrew; Koekemoer, Anton; Konidaris,Nicholas P.; Lotz, Jennifer M.; Willmer, Christopher N. A.

2006-10-13

We report on the results of a visual search for galaxy-scale strong gravitational lenses over 650 arcmin{sup 2} of HST/ACS (F606W and F814W) imaging in the DEEP2-Extended Groth Strip (EGS). In addition to a previously-known Einstein Cross also found by our search (the 'Cross', HSTJ141735+52264, z{sub lens} = 0.8106, z{sub source} = 3.40), we identify two new strong galaxy-galaxy lenses with multiple extended arcs. The first, HSTJ141820+52361 (the 'Dewdrop'; z{sub lens} = 0.5798), lenses two distinct extended sources into two pairs of arcs (z{sub source} = 0.9818), while the second, HSTJ141833+52435 (the 'Anchor'; z{sub lens} = 0.4625), produces a single pair of arcs (z{sub lens} not yet known). Four less convincing arc/counter-arc and two-image lens candidates are also found and presented for completeness. Lenses are found in a both underdense and overdense local environments, as characterized by a robust measure, 1+{delta}{sub 3}, a normalized density that uses the distance to the third nearest neighbor. All three definite lenses are fit reasonably well by simple singular isothermal ellipsoid models including external shear, giving {chi}{sub {nu}}{sup 2} values close to unity. These shears are much greater than those implied by a simple consideration of the three-dimensional convergence and shear from galaxies along the line of sight, where each galaxy is approximated by a singular isothermal sphere halo truncated at 200 h{sup -1} kpc. This shows how a realistic treatment of galaxies and the large scale structure they are embedded in is necessary, and that simply characterizing the very-local environment may be insufficient.

Separating intrinsic alignment and galaxy-galaxy lensing

International Nuclear Information System (INIS)

Blazek, Jonathan; Seljak, Uroš; Mandelbaum, Rachel; Nakajima, Reiko

2012-01-01

The coherent physical alignment of galaxies is an important systematic for gravitational lensing studies as well as a probe of the physical mechanisms involved in galaxy formation and evolution. We develop a formalism for treating this intrinsic alignment (IA) in the context of galaxy-galaxy lensing and present an improved method for measuring IA contamination, which can arise when sources physically associated with the lens are placed behind the lens due to photometric redshift scatter. We apply the technique to recent Sloan Digital Sky Survey (SDSS) measurements of Luminous Red Galaxy lenses and typical ( ∼ L * ) source galaxies with photometric redshifts selected from the SDSS imaging data. Compared to previous measurements, this method has the advantage of being fully self-consistent in its treatment of the IA and lensing signals, solving for the two simultaneously. We find an IA signal consistent with zero, placing tight constraints on both the magnitude of the IA effect and its potential contamination to the lensing signal. While these constraints depend on source selection and redshift quality, the method can be applied to any measurement that uses photometric redshifts. We obtain a model-independent upper-limit of roughly 10% IA contamination for projected separations of r p ≈ 0.1–10 h −1 Mpc. With more stringent photo-z cuts and reasonable assumptions about the physics of intrinsic alignments, this upper limit is reduced to 1–2%. These limits are well below the statistical error of the current lensing measurements. Our results suggest that IA will not present intractable challenges to the next generation of galaxy-galaxy lensing experiments, and the methods presented here should continue to aid in our understanding of alignment processes and in the removal of IA from the lensing signal

Plasma surface modification of rigid contact lenses decreases bacterial adhesion.

Science.gov (United States)

Wang, Yingming; Qian, Xuefeng; Zhang, Xiaofeng; Xia, Wei; Zhong, Lei; Sun, Zhengtai; Xia, Jing

2013-11-01

Contact lens safety is an important topic in clinical studies. Corneal infections usually occur because of the use of bacteria-carrying contact lenses. The current study investigated the impact of plasma surface modification on bacterial adherence to rigid contact lenses made of fluorosilicone acrylate materials. Boston XO and XO2 contact lenses were modified using plasma technology (XO-P and XO2-P groups). Untreated lenses were used as controls. Plasma-treated and control lenses were incubated in solutions containing Staphylococcus aureus or Pseudomonas aeruginosa. MTT colorimetry, colony-forming unit counting method, and scanning electron microscopy were used to measure bacterial adhesion. MTT colorimetry measurements showed that the optical density (OD) values of XO-P and XO2-P were significantly lower than those of XO and XO2, respectively, after incubation with S. aureus (P lenses and to the XO2-P versus XO2 lenses incubated with S. aureus (P lenses incubated with P. aeruginosa (P lenses. Plasma surface modification can significantly decrease bacterial adhesion to fluorosilicone acrylate contact lenses. This study provides important evidence of a unique benefit of plasma technology in contact lens surface modification.

Predicting gravitational lensing by stellar remnants

Science.gov (United States)

Harding, Alexander J.; Stefano, R. Di; Lépine, S.; Urama, J.; Pham, D.; Baker, C.

2018-03-01

Gravitational lensing provides a means to measure mass that does not rely on detecting and analysing light from the lens itself. Compact objects are ideal gravitational lenses, because they have relatively large masses and are dim. In this paper, we describe the prospects for predicting lensing events generated by the local population of compact objects, consisting of 250 neutron stars, five black holes, and ≈35 000 white dwarfs. By focusing on a population of nearby compact objects with measured proper motions and known distances from us, we can measure their masses by studying the characteristics of any lensing event they generate. Here, we concentrate on shifts in the position of a background source due to lensing by a foreground compact object. With Hubble Space Telescope, JWST, and Gaia, measurable centroid shifts caused by lensing are relatively frequent occurrences. We find that 30-50 detectable events per decade are expected for white dwarfs. Because relatively few neutron stars and black holes have measured distances and proper motions, it is more difficult to compute realistic rates for them. However, we show that at least one isolated neutron star has likely produced detectable events during the past several decades. This work is particularly relevant to the upcoming data releases by the Gaia mission and also to data that will be collected by JWST. Monitoring predicted microlensing events will not only help to determine the masses of compact objects, but will also potentially discover dim companions to these stellar remnants, including orbiting exoplanets.

Factors influencing bacterial adhesion to contact lenses

OpenAIRE

Dutta, Debarun; Cole, Nerida; Willcox, Mark

2012-01-01

The process of any contact lens related keratitis generally starts with the adhesion of opportunistic pathogens to contact lens surface. This article focuses on identifying the factors which have been reported to affect bacterial adhesion to contact lenses. Adhesion to lenses differs between various genera/species/strains of bacteria. Pseudomonas aeruginosa, which is the predominant causative organism, adheres in the highest numbers to both hydrogel and silicone hydrogel lenses in vitro. The ...

DESIGN OF THE MULTIORDER INTRAOCULAR LENSES

Directory of Open Access Journals (Sweden)

V. G. Kolobrodov

2015-01-01

Full Text Available Intraocular lenses (IOLs are used to replace the natural crystalline lens of the eye. Just few basic designs of IOLs are used clinically. Multiorder diffractive lenses (MODL which operate simultaneously in several diffractive orders were proposed to decrease the chromatic aberration. Properties analysis of MODL showed a possibility to use them to develop new designs of IOLs. The purpose of this paper was to develop a new method of designing of multiorder intraocular lenses with decreased chromatic aberration. The theoretical research of the lens properties was carried out. The diffraction efficiency dependence with the change of wavelength was studied. A computer simulation of MODL in a schematic model of the human eye was carried out. It is found the capability of the multiorder diffractive lenses to focus polychromatic light into a segment on the optical axis with high diffraction efficiency. At each point of the segment is present each component of the spectral range, which will build a color image in combination. The paper describes the new design method of intraocular lenses with reduced chromaticism and with endless adaptation. An optical system of an eye with an intraocular lens that provides sharp vision of objects located at a distance of 700 mm to infinity is modeled.

Lensing reconstruction from a patchwork of polarization maps

International Nuclear Information System (INIS)

Namikawa, Toshiya; Nagata, Ryo

2014-01-01

The lensing signals involved in CMB polarization maps have already been measured with ground-based experiments such as SPTpol and POLARBEAR, and would become important as a probe of cosmological and astrophysical issues in the near future. Sizes of polarization maps from ground-based experiments are, however, limited by contamination of long wavelength modes of observational noise. To further extract the lensing signals, we explore feasibility of measuring lensing signals from a collection of small sky maps each of which is observed separately by a ground-based large telescope, i.e., lensing reconstruction from a patchwork map of large sky coverage organized from small sky patches. We show that, although the B-mode power spectrum obtained from the patchwork map is biased due to baseline uncertainty, bias on the lensing potential would be negligible if the B-mode on scales larger than the blowup scale of 1/f noise is removed in the lensing reconstruction. As examples of cosmological applications, we also show 1) the cross-correlations between the reconstructed lensing potential and full-sky temperature/polarization maps from satellite missions such as PLANCK and LiteBIRD, and 2) the use of the reconstructed potential for delensing B-mode polarization of LiteBIRD observation

Experimental studies of stable confined electron clouds using Gabor lenses

CERN Document Server

Meusel, O.; Glaeser, B.; Schulte, K.

2013-04-22

Based on the idea of D. Gabor [1] space charge lenses are under investigation to be a powerful focussing device for intense ion beams. A stable confined electron column is used to provide strong radially symmetric electrostatic focussing, e.g. for positively charged ion beams. The advantages of Gabor lenses are a mass independent focussing strength, space charge compensation of the ion beam and reduced magnetic or electric fields compared to conventional focussing devices. Collective phenomena of the electron cloud result in aberrations and emittance growth of the ion beam. The knowledge of the behaviour of the electron cloud prevents a decrease of the beam brilliance. Numerical models developed to describe the electron confinement and dynamics within a Gabor lens help to understand the interaction of the ion beam with the electron column and show the causes of non-neutral plasma instabilities. The diagnosis of the electron cloud properties helps to evaluate the numerical models and to investigate the influen...

Magnified Weak Lensing Cross Correlation Tomography

Energy Technology Data Exchange (ETDEWEB)

Ulmer, Melville P., Clowe, Douglas I.

2010-11-30

nights on 4-m class telescopes, which gives concrete evidence of strong community support for this project. The WLT technique is based on the dependence of the gravitational shear signal on the angular diameter distances between the observer, the lens, and the lensed galaxy to measure cosmological parameters. By taking the ratio of measured shears of galaxies with different redshifts around the same lens, one obtains a measurement of the ratios of the angular diameter distances involved. Making these observations over a large range of lenses and background galaxy redshifts will measure the history of the expansion rate of the universe. Because this is a purely geometric measurement, it is insensitive to any form of evolution of objects or the necessity to understand the physics in the early universe. Thus, WLT was identified by the Dark Energy Task Force as perhaps the best method to measure the evolution of DE. To date, however, the conjecture of the DETF has not been experimentally verified, but will be by the proposed project. The primary reason for the lack of tomography measurements is that one must have an exceptional data-set to attempt the measurement. One needs both extremely good seeing (or space observations) in order to minimize the point spread function smearing corrections on weak lensing shear measurements and deep, multi-color data, from B to z, to measure reliable photometric redshifts of the background galaxies being lensed (which are typically too faint to obtain spectroscopic redshifts). Because the entire process from multi-drizzling the HST images, and then creating shear maps, to gathering the necessary ground based observations, to generating photo-zs and then carrying out the tomography is a complicated task, until the creation of our team, nobody has taken the time to connect all the levels of expertise necessary to carry out this project based on HST archival data. Our data are being used in 2 Ph.D. theses. Kellen Murphy, at Ohio University, is

Precision cosmology with weak gravitational lensing

Science.gov (United States)

Hearin, Andrew P.

In recent years, cosmological science has developed a highly predictive model for the universe on large scales that is in quantitative agreement with a wide range of astronomical observations. While the number and diversity of successes of this model provide great confidence that our general picture of cosmology is correct, numerous puzzles remain. In this dissertation, I analyze the potential of planned and near future galaxy surveys to provide new understanding of several unanswered questions in cosmology, and address some of the leading challenges to this observational program. In particular, I study an emerging technique called cosmic shear, the weak gravitational lensing produced by large scale structure. I focus on developing strategies to optimally use the cosmic shear signal observed in galaxy imaging surveys to uncover the physics of dark energy and the early universe. In chapter 1 I give an overview of a few unsolved mysteries in cosmology and I motivate weak lensing as a cosmological probe. I discuss the use of weak lensing as a test of general relativity in chapter 2 and assess the threat to such tests presented by our uncertainty in the physics of galaxy formation. Interpreting the cosmic shear signal requires knowledge of the redshift distribution of the lensed galaxies. This redshift distribution will be significantly uncertain since it must be determined photometrically. In chapter 3 I investigate the influence of photometric redshift errors on our ability to constrain dark energy models with weak lensing. The ability to study dark energy with cosmic shear is also limited by the imprecision in our understanding of the physics of gravitational collapse. In chapter 4 I present the stringent calibration requirements on this source of uncertainty. I study the potential of weak lensing to resolve a debate over a long-standing anomaly in CMB measurements in chapter 5. Finally, in chapter 6 I summarize my findings and conclude with a brief discussion of my

Nanoplasmonic lenses for bacteria sorting (Presentation Recording)

Science.gov (United States)

Zhu, Xiangchao; Yanik, Ahmet A.

2015-08-01

We demonstrate that patches of two dimensional arrays of circular plasmonic nanoholes patterned on gold-titanium thin film enables subwavelength focusing of visible light in far field region. Efficient coupling of the light with the excited surface plasmon at metal dielectric interface results in strong light transmission. As a result, surface plasmon plays an important role in the far field focusing behavior of the nanohole-aperture patches device. Furthermore, the focal length of the focused beam was found to be predominantly dependent on the overall size of the patch, which is in good agreement with that calculated by Rayleigh-Sommerfield integral formula. The focused light beam can be utilized to separate bio-particles in the dynamic range from 0.1 μm to 1 μm through mainly overcoming the drag force induced by fluid flow. In our proposed model, focused light generated by our plasmonic lenses will push the larger bio-particles in size back to the source of fluid flow and allow the smaller particles to move towards the central aperture of the patch. Such a new kind of plasmonic lenses open up possibility of sorting bacterium-like particles with plasmonic nanolenses, and also represent a promising tool in the field of virology.

Planck 2015 results: XV. Gravitational lensing

DEFF Research Database (Denmark)

Ade, P. A R; Aghanim, N.; Arnaud, M.

2016-01-01

We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40σ), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator, we detect lensing at a significance of 5σ. We...

Bacterial adhesion to unworn and worn silicone hydrogel lenses.

Science.gov (United States)

Vijay, Ajay Kumar; Zhu, Hua; Ozkan, Jerome; Wu, Duojia; Masoudi, Simin; Bandara, Rani; Borazjani, Roya N; Willcox, Mark D P

2012-08-01

The objective of this study was to determine the bacterial adhesion to various silicone hydrogel lens materials and to determine whether lens wear modulated adhesion. Bacterial adhesion (total and viable cells) of Staphylococcus aureus (31, 38, and ATCC 6538) and Pseudomonas aeruginosa (6294, 6206, and GSU-3) to 10 commercially available different unworn and worn silicone hydrogel lenses was measured. Results of adhesion were correlated to polymer and surface properties of contact lenses. S. aureus adhesion to unworn lenses ranged from 2.8 × 10 to 4.4 × 10 colony forming units per lens. The highest adhesion was to lotrafilcon A lenses, and the lowest adhesion was to asmofilcon A lenses. P. aeruginosa adhesion to unworn lenses ranged from 8.9 × 10 to 3.2 × 10 colony forming units per lens. The highest adhesion was to comfilcon A lenses, and the lowest adhesion was to asmofilcon A and balafilcon A lenses. Lens wear altered bacterial adhesion, but the effect was specific to lens and strain type. Adhesion of bacteria, regardless of genera/species or lens wear, was generally correlated with the hydrophobicity of the lens; the less hydrophobic the lens surface, the greater the adhesion. P. aeruginosa adhered in higher numbers to lenses in comparison with S. aureus strains, regardless of the lens type or lens wear. The effect of lens wear was specific to strain and lens. Hydrophobicity of the silicone hydrogel lens surface influenced the adhesion of bacterial cells.

Fimbrolide-coated antimicrobial lenses: their in vitro and in vivo effects.

Science.gov (United States)

Zhu, Hua; Kumar, Ajay; Ozkan, Jerome; Bandara, Rani; Ding, Aidong; Perera, Indrani; Steinberg, Peter; Kumar, Naresh; Lao, William; Griesser, Stefani S; Britcher, Leanne; Griesser, Hans J; Willcox, Mark D P

2008-05-01

To examine the ability of contact lenses coated with fimbrolides, inhibitors of bacterial quorum sensing, to prevent microbial adhesion and their safety during short-term clinical assessment. A fimbrolide was covalently attached to commercially available high Dk contact lenses. Subsequently Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, or Acanthamoeba sp. were added to the lenses and control uncoated contact lenses. Lenses plus microbes were incubated for 24 h, then washed thoroughly to remove non-adherent microbes. Lenses were macerated and resulting slurry plated onto agar plates. After appropriate incubation, the numbers of colony forming units of bacteria (or numbers of Acanthamoeba trophozoites measured using a hemocytometer) from fimbrolide-coated and uncoated lenses were examined. A Guinea Pig model of lens wear was used to assess the safety of lenses worn on a continuous basis for 1 month. In a separate study, 10 subjects wore fimbrolide-coated lenses for 24 h. The responses of the Guinea Pigs and human volunteers to the lenses were assessed by slit lamp examination. The fimbrolides-coated lenses reduced the adhesion of all bacterial strains tested, with reductions occurring of between 67 and 92%. For Acanthamoeba a reduction of 70% was seen. There were no significant differences in ocular responses to fimbrolide-coated lenses compared with controls in either the 1 month animal model or overnight human trial. Fimbrolide-coated lenses show promise as an antibacterial and anti-acanthamoebal coating on contact lenses and appear to be safe when worn on the eye in an animal model.

Contact lenses fitting after intracorneal ring segments implantation in keratoconus

Directory of Open Access Journals (Sweden)

Luciane Bugmann Moreira

2013-08-01

Full Text Available PURPOSE: Evaluate contact lenses fitting after intracorneal ring implantation for keratoconus, its visual acuity and comfort. METHODS: Retrospective study of patients undergoing contact lenses fitting, after intracorneal ring for keratoconus. The criterion for contact lens fitting was unsatisfactory visual acuity with spectacle correction as referred by the patients. All patients were intolerants to contact lenses prior to intracorneal implantation. Visual acuity analysis was done by conversion of Snellen to logMAR scales. The comfort was evaluated according subjective questioning of good, medium or poor comfort. RESULTS: Nineteen patients were included in the study. Two patients (10.5% did not achieved good comfort with contact lenses and underwent penetrating keratoplasties. All the others 17 patients showed good or medium comfort. Four rigid gas-permeable contact lenses were fitted, one piggyback approach, 3 toric soft contact lenses, 2 soft lenses specially design for keratoconus and 7 disposable soft lenses. The average visual acuity improved from 0.77 ± 0.37 to 0.19 ± 0.13 logMAR units after contact lenses fitting. CONCLUSION: Contact lens fitting after intracorneal ring is possible, provides good comfort, improves visual acuity, and therefore, may postpone the need for penetrating keratoplasty.

Lensing of Fast Radio Bursts as a Probe of Compact Dark Matter.

Science.gov (United States)

Muñoz, Julian B; Kovetz, Ely D; Dai, Liang; Kamionkowski, Marc

2016-08-26

The possibility that part of the dark matter is made of massive compact halo objects (MACHOs) remains poorly constrained over a wide range of masses, and especially in the 20-100  M_{⊙} window. We show that strong gravitational lensing of extragalactic fast radio bursts (FRBs) by MACHOs of masses larger than ∼20  M_{⊙} would result in repeated FRBs with an observable time delay. Strong lensing of a FRB by a lens of mass M_{L} induces two images, separated by a typical time delay ∼few×(M_{L}/30  M_{⊙})  msec. Considering the expected FRB detection rate by upcoming experiments, such as canadian hydrogen intensity mapping experiment (CHIME), of 10^{4} FRBs per year, we should observe from tens to hundreds of repeated bursts yearly, if MACHOs in this window make up all the dark matter. A null search for echoes with just 10^{4} FRBs would constrain the fraction f_{DM} of dark matter in MACHOs to f_{DM}≲0.08 for M_{L}≳20  M_{⊙}.

Low-energy beam transport using space-charge lenses

International Nuclear Information System (INIS)

Meusel, O.; Bechtold, A.; Pozimski, J.; Ratzinger, U.; Schempp, A.; Klein, H.

2005-01-01

Space-charge lenses (SCL) of the Gabor type provide strong cylinder symmetric focusing for low-energy ion beams using a confined nonneutral plasma. They need modest magnetic and electrostatic field strength and provide a short installation length when compared to conventional LEBT-lenses like quadrupoles and magnetic solenoids. The density distribution of the enclosed space charge within the Gabor lens is given by the confinement in transverse and longitudinal directions. In the case of a positive ion beam, the space charge of the confined electron cloud may cause an overcompensation of the ion beam space-charge force and consequently focuses the beam. To investigate the capabilities of an SCL double-lens system for ion beam into an RFQ, a test injector was installed at IAP and put into operation successfully. Furthermore, to study the focusing capabilities of this lens at beam energies up to 500 keV, a high-field Gabor lens was built and installed downstream of the RFQ. Experimental results of the beam injection into the RFQ are presented as well as those of these first bunched beam-focusing tests with the 110 A keV He + beam

Relative radiosensitivity of rat lenses as a function of age

International Nuclear Information System (INIS)

Merriam, G.R. Jr.; Szechter, A.

1975-01-01

The effect of age on the development of radiation cataracts in rat lenses has been investigated using the Columbia--Sherman rat as an experiment model. A detailed pattern of age dependence was obtained at several different dose levels. In general at dose levels from 200 to 300 rads the lens changes occurred sooner and progressed faster in the adult lenses than in young lenses. In the dose range from 300 rads to 900 rads opacities developed sooner in the young lenses but progression was faster and severe opacities developed sooner in adult lenses. Above 900 rads opacities developed sooner and progressed faster in the young lenses. (U.S.)

MAGNIFICATION AS A PROBE OF DARK MATTER HALOS AT HIGH REDSHIFTS

International Nuclear Information System (INIS)

Van Waerbeke, L.; Ford, J.; Milkeraitis, M.; Hildebrandt, H.

2010-01-01

We propose a new approach for measuring the mass profile of dark matter halos by stacking the lensing magnification of distant background galaxies behind groups and clusters of galaxies. The main advantage of lensing magnification is that, unlike lensing shear, it relies on accurate photometric redshifts only and not on galaxy shapes, thus enabling the study of the dark matter distribution with unresolved source galaxies. We present a feasibility study, using a real population of z ≥ 2.5 Lyman break galaxies as source galaxies, and where, similar to galaxy-galaxy lensing, foreground lenses are stacked in order to increase the signal-to-noise ratio. We find that there is an interesting new observational window for gravitational lensing as a probe of dark matter halos at high redshift, which does not require a measurement of galaxy shapes.

Models of the Strongly Lensed Quasar DES J0408-5354

Energy Technology Data Exchange (ETDEWEB)

Agnello, A.; et al.

2017-02-01

We present gravitational lens models of the multiply imaged quasar DES J0408-5354, recently discovered in the Dark Energy Survey (DES) footprint, with the aim of interpreting its remarkable quad-like configuration. We first model the DES single-epoch $grizY$ images as a superposition of a lens galaxy and four point-like objects, obtaining spectral energy distributions (SEDs) and relative positions for the objects. Three of the point sources (A,B,D) have SEDs compatible with the discovery quasar spectra, while the faintest point-like image (G2/C) shows significant reddening and a `grey' dimming of $\\approx0.8$mag. In order to understand the lens configuration, we fit different models to the relative positions of A,B,D. Models with just a single deflector predict a fourth image at the location of G2/C but considerably brighter and bluer. The addition of a small satellite galaxy ($R_{\\rm E}\\approx0.2$") in the lens plane near the position of G2/C suppresses the flux of the fourth image and can explain both the reddening and grey dimming. All models predict a main deflector with Einstein radius between $1.7"$ and $2.0",$ velocity dispersion $267-280$km/s and enclosed mass $\\approx 6\\times10^{11}M_{\\odot},$ even though higher resolution imaging data are needed to break residual degeneracies in model parameters. The longest time-delay (B-A) is estimated as $\\approx 85$ (resp. $\\approx125$) days by models with (resp. without) a perturber near G2/C. The configuration and predicted time-delays of J0408-5354 make it an excellent target for follow-up aimed at understanding the source quasar host galaxy and substructure in the lens, and measuring cosmological parameters. We also discuss some lessons learnt from J0408-5354 on lensed quasar finding strategies, due to its chromaticity and morphology.

Performance characterization of UV science cameras developed for the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP)

Science.gov (United States)

Champey, P.; Kobayashi, K.; Winebarger, A.; Cirtain, J.; Hyde, D.; Robertson, B.; Beabout, D.; Beabout, B.; Stewart, M.

2014-07-01

The NASA Marshall Space Flight Center (MSFC) has developed a science camera suitable for sub-orbital missions for observations in the UV, EUV and soft X-ray. Six cameras will be built and tested for flight with the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP), a joint National Astronomical Observatory of Japan (NAOJ) and MSFC sounding rocket mission. The goal of the CLASP mission is to observe the scattering polarization in Lyman-α and to detect the Hanle effect in the line core. Due to the nature of Lyman-α polarizationin the chromosphere, strict measurement sensitivity requirements are imposed on the CLASP polarimeter and spectrograph systems; science requirements for polarization measurements of Q/I and U/I are 0.1% in the line core. CLASP is a dual-beam spectro-polarimeter, which uses a continuously rotating waveplate as a polarization modulator, while the waveplate motor driver outputs trigger pulses to synchronize the exposures. The CCDs are operated in frame-transfer mode; the trigger pulse initiates the frame transfer, effectively ending the ongoing exposure and starting the next. The strict requirement of 0.1% polarization accuracy is met by using frame-transfer cameras to maximize the duty cycle in order to minimize photon noise. The CLASP cameras were designed to operate with ≤ 10 e-/pixel/second dark current, ≤ 25 e- read noise, a gain of 2.0 +- 0.5 and ≤ 1.0% residual non-linearity. We present the results of the performance characterization study performed on the CLASP prototype camera; dark current, read noise, camera gain and residual non-linearity.

The Lyman-α forest in three dimensions: measurements of large scale flux correlations from BOSS 1st-year data

Energy Technology Data Exchange (ETDEWEB)

Slosar, Anže [Brookhaven National Laboratory, Blgd 510, Upton NY 11375 (United States); Font-Ribera, Andreu [Institut de Ciències de l' Espai (CSIC-IEEC), Campus UAB, Fac. Ciències, torre C5 parell 2, Bellaterra, Catalonia (Spain); Pieri, Matthew M. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, Colorado 80309 (United States); Rich, James; Goff, Jean-Marc Le; Charlassier, Romain [CEA, Centre de Saclay, IRFU, 91191 Gif-sur-Yvette (France); Aubourg, Éric; Busca, Nicolas; Hamilton, Jean-Christophe [APC, Université Paris Diderot-Paris 7, CNRS/IN2P3, CEA, Observatoire de Paris, 10, rue A. Domon and L. Duquet, Paris (France); Brinkmann, Jon [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349 (United States); Carithers, Bill; Cortês, Marina; Ho, Shirley; McDonald, Patrick [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Croft, Rupert [Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Dawson, Kyle S. [University of Utah, Dept. of Physics and Astronomy, 115 S 1400 E, Salt Lake City, UT 84112 (United States); Eisenstein, Daniel [Harvard College Observatory, 60 Garden St., Cambridge MA 02138 (United States); Lee, Khee-Gan; Lupton, Robert [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Medolin, Bumbarija, E-mail: anze@bnl.gov [104-20 Queens Blvd 17A, Forest Hills, NY 11375 (United States); and others

2011-09-01

Using a sample of approximately 14,000 z > 2.1 quasars observed in the first year of the Baryon Oscillation Spectroscopic Survey (BOSS), we measure the three-dimensional correlation function of absorption in the Lyman-α forest. The angle-averaged correlation function of transmitted flux (F = e{sup −τ}) is securely detected out to comoving separations of 60 h{sup −1}Mpc, the first detection of flux correlations across widely separated sightlines. A quadrupole distortion of the redshift-space correlation function by peculiar velocities, the signature of the gravitational instability origin of structure in the Lyman-α forest, is also detected at high significance. We obtain a good fit to the data assuming linear theory redshift-space distortion and linear bias of the transmitted flux, relative to the matter fluctuations of a standard ΛCDM cosmological model (inflationary cold dark matter with a cosmological constant). At 95% confidence, we find a linear bias parameter 0.16 < b < 0.24 and redshift-distortion parameter 0.44 < β < 1.20, at central redshift z = 2.25, with a well constrained combination b(1+β) = 0.336±0.012. The errors on β are asymmetric, with β = 0 excluded at over 5σ confidence level. The value of β is somewhat low compared to theoretical predictions, and our tests on synthetic data suggest that it is depressed (relative to expectations for the Lyman-α forest alone) by the presence of high column density systems and metal line absorption. These results set the stage for cosmological parameter determinations from three-dimensional structure in the Lyman-α forest, including anticipated constraints on dark energy from baryon acoustic oscillations.

Weak lensing in generalized gravity theories

International Nuclear Information System (INIS)

Acquaviva, Viviana; Baccigalupi, Carlo; Perrotta, Francesca

2004-01-01

We extend the theory of weak gravitational lensing to cosmologies with generalized gravity, described in the Lagrangian by a generic function depending on the Ricci scalar and a nonminimal coupled scalar field. We work out the generalized Poisson equations relating the dynamics of the fluctuating components to the two gauge-invariant scalar gravitational potentials, fixing the contributions from the modified background expansion and fluctuations. We show how the lensing equation gets modified by the cosmic expansion as well as by the presence of anisotropic stress, which is non-null at the linear level both in scalar-tensor gravity and in theories where the gravitational Lagrangian term features a nonminimal dependence on the Ricci scalar. Starting from the geodesic deviation, we derive the generalized expressions for the shear tensor and projected lensing potential, encoding the spacetime variation of the effective gravitational constant and isolating the contribution of the anisotropic stress, which introduces a correction due to the spatial correlation between the gravitational potentials. Finally, we work out the expressions of the lensing convergence power spectrum as well as the correlation between the lensing potential and the integrated Sachs-Wolfe effect affecting cosmic microwave background total intensity and polarization anisotropies. To illustrate phenomenologically the effects, we work out approximate expressions for the quantities above in extended quintessence scenarios where the scalar field coupled to gravity plays the role of the dark energy

Effect of cholesterol deposition on bacterial adhesion to contact lenses.

Science.gov (United States)

Babaei Omali, Negar; Zhu, Hua; Zhao, Zhenjun; Ozkan, Jerome; Xu, Banglao; Borazjani, Roya; Willcox, Mark D P

2011-08-01

To examine the effect of cholesterol on the adhesion of bacteria to silicone hydrogel contact lenses. Contact lenses, collected from subjects wearing Acuvue Oasys or PureVision lenses, were extracted in chloroform:methanol (1:1, v/v) and amount of cholesterol was estimated by thin-layer chromatography. Unworn lenses were soaked in cholesterol, and the numbers of Pseudomonas aeruginosa strains or Staphylococcus aureus strains that adhered to the lenses were measured. Cholesterol was tested for effects on bacterial growth by incubating bacteria in medium containing cholesterol. From ex vivo PureVision lenses, 3.4 ± 0.3 μg/lens cholesterol was recovered, and from Acuvue Oasys lenses, 2.4 ± 0.2 to 1.0 ± 0.1 μg/lens cholesterol was extracted. Cholesterol did not alter the total or viable adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). However, worn PureVision lenses reduced the numbers of viable cells of P. aeruginosa (5.8 ± 0.4 log units) compared with unworn lenses (6.4 ± 0.2 log units, p = 0.001). Similarly, there were fewer numbers of S. aureus 031 adherent to worn PureVision (3.05 ± 0.8 log units) compared with unworn PureVision (4.6 ± 0.3 log units, p = 0.0001). Worn Acuvue Oasys lenses did not affect bacterial adhesion. Cholesterol showed no effect on the growth of any test strain. Although cholesterol has been shown to adsorb to contact lenses during wear, this lipid does not appear to modulate bacterial adhesion to a lens surface.

Probing supervoids with weak lensing

Science.gov (United States)

Higuchi, Yuichi; Inoue, Kaiki Taro

2018-05-01

The cosmic microwave background (CMB) has non-Gaussian features in the temperature fluctuations. An anomalous cold spot surrounded with a hot ring, called the Cold Spot, is one of such features. If a large underdense region (supervoid) resides towards the Cold Spot, we would be able to detect a systematic shape distortion in the images of background source galaxies via weak lensing effect. In order to estimate the detectability of such signals, we used the data of N-body simulations to simulate full-sky ray-tracing of source galaxies. We searched for a most prominent underdense region using the simulated convergence maps smoothed at a scale of 20° and obtained tangential shears around it. The lensing signal expected in a concordant Λ cold dark matter model can be detected at a signal-to-noise ratio S/N ˜ 3. If a supervoid with a radius of ˜200 h-1 Mpc and a density contrast δ0 ˜ -0.3 at the centre resides at a redshift z ˜ 0.2, on-going and near-future weak gravitational lensing surveys would detect a lensing signal with S/N ≳ 4 without resorting to stacking. From the tangential shear profile, we can obtain a constraint on the projected mass distribution of the supervoid.

Constraining the primordial power spectrum from SNIa lensing dispersion

Energy Technology Data Exchange (ETDEWEB)

Ben-Dayan, Ido [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kalaydzhyan, Tigran [State Univ. of New York, Stony Brook, NY (United States). Dept. of Physics and Astronomy

2013-09-15

The (absence of detecting) lensing dispersion of Supernovae type Ia (SNIa) can be used as a novel and extremely efficient probe of cosmology. In this preliminary example we analyze its consequences for the primordial power spectrum. The main setback is the knowledge of the power spectrum in the non-linear regime, 1 Mpc{sup -1}lensing dispersion and conservative estimates in this regime of wavenumbers, we show how the current upper bound {sigma}{sub {mu}}(z=1)<0.12 on existing data gives strong indirect constraints on the primordial power spectrum. The probe extends our handle on the spectrum to a total of 12-15 inflation e-folds. These constraints are so strong that they are already ruling out a large portion of the parameter space allowed by PLANCK for running {alpha}{identical_to}dn{sub s}/d ln k and running of running {beta}{identical_to}d{sup 2}n{sub s}/d ln k{sup 2}. The bounds follow a linear relation to a very good accuracy. A conservative bound disfavours any enhancement above the line {beta}(k{sub 0})=0.032-0.41{alpha}(k{sub 0}) and a realistic estimate disfavours any enhancement above the line {beta}(k{sub 0})=0.019-0.45{alpha}(k{sub 0}).

Lensing smoothing of BAO wiggles

Energy Technology Data Exchange (ETDEWEB)

Dio, Enea Di, E-mail: enea.didio@oats.inaf.it [INAF—Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34143 Trieste (Italy)

2017-03-01

We study non-perturbatively the effect of the deflection angle on the BAO wiggles of the matter power spectrum in real space. We show that from redshift z ∼2 this introduces a dispersion of roughly 1 Mpc at BAO scale, which corresponds approximately to a 1% effect. The lensing effect induced by the deflection angle, which is completely geometrical and survey independent, smears out the BAO wiggles. The effect on the power spectrum amplitude at BAO scale is about 0.1 % for z ∼2 and 0.2 % for z ∼4. We compare the smoothing effects induced by the lensing potential and non-linear structure formation, showing that the two effects become comparable at z ∼ 4, while the lensing effect dominates for sources at higher redshifts. We note that this effect is not accounted through BAO reconstruction techniques.

Probabilistic Cosmological Mass Mapping from Weak Lensing Shear

Energy Technology Data Exchange (ETDEWEB)

Schneider, M. D.; Dawson, W. A. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Ng, K. Y. [University of California, Davis, Davis, CA 95616 (United States); Marshall, P. J. [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94035 (United States); Meyers, J. E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Bard, D. J., E-mail: schneider42@llnl.gov, E-mail: dstn@cmu.edu, E-mail: boutigny@in2p3.fr, E-mail: djbard@slac.stanford.edu, E-mail: jmeyers314@stanford.edu [National Energy Research Scientific Computing Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720-8150 (United States)

2017-04-10

We infer gravitational lensing shear and convergence fields from galaxy ellipticity catalogs under a spatial process prior for the lensing potential. We demonstrate the performance of our algorithm with simulated Gaussian-distributed cosmological lensing shear maps and a reconstruction of the mass distribution of the merging galaxy cluster Abell 781 using galaxy ellipticities measured with the Deep Lens Survey. Given interim posterior samples of lensing shear or convergence fields on the sky, we describe an algorithm to infer cosmological parameters via lens field marginalization. In the most general formulation of our algorithm we make no assumptions about weak shear or Gaussian-distributed shape noise or shears. Because we require solutions and matrix determinants of a linear system of dimension that scales with the number of galaxies, we expect our algorithm to require parallel high-performance computing resources for application to ongoing wide field lensing surveys.

From Spheric to Aspheric Solid Polymer Lenses: A Review

Directory of Open Access Journals (Sweden)

Kuo-Yung Hung

2011-01-01

Full Text Available This paper presents a new approach in the use of MEMS technology to fabricate micro-optofluidic polymer solid lenses in order to achieve the desired profile, focal length, numerical aperture, and spot size. The resulting polymer solid lenses can be applied in optical data storage systems, imaging systems, and automated optical inspection systems. In order to meet the various needs of different applications, polymer solid lenses may have a spherical or aspherical shape. The method of fabricating polymer solid lenses is different from methods used to fabricate tunable lenses with variable focal length or needing an external control system to change the lens geometry. The current trend in polymer solid lenses is toward the fabrication of microlenses with a high numerical aperture, small clear aperture (<2 mm, and high transmittance. In this paper we focus on the use of thermal energy and electrostatic force in shaping the lens profile, including both spherical and aspherical lenses. In addition, the paper discusses how to fabricate a lens with a high numerical aperture of 0.6 using MEMS and also compares the optical characteristics of polymer lens materials, including SU-8, Norland Optical Adhesive (NOA, and cyclic olefin copolymer (COC. Finally, new concepts and applications related to micro-optofluidic lenses and polymer materials are also discussed.

Microcyst response to high Dk/t silicone hydrogel contact lenses.

Science.gov (United States)

Keay, L; Sweeney, D F; Jalbert, I; Skotnitsky, C; Holden, B A

2000-11-01

To investigate the microcyst response to extended wear (EW) with high oxygen transmissible (Dk/t) silicone hydrogel lenses. Microcysts were monitored for 12 months in subjects wearing low Dk/t hydrogel lenses on a 6-night EW schedule or high Dk/t hydrogel lenses on a 30-night EW schedule. Subjects wearing low Dk/t lenses transferred to the high Dk/t EW lenses and schedule after 12 months and were monitored for a further 6 months. The mean number of microcysts did not deviate from baseline in the high Dk/t group. Microcysts in the low Dk/t group increased over 12 months, and more microcysts were observed in low Dk/t lens wearers compared with high Dk/t lens wearers after 3 months. Microcysts increased in 50% of subjects 1 week after transfer to high Dk/t lenses and returned to baseline levels seen with high Dk/t lens wear within 3 months. EW with high Dk/t silicone hydrogel lenses did not cause an increase in microcyst numbers. It is not necessary to discontinue lens wear with patients who transfer from low to high Dk/t lenses because the increase in microcysts is transitory. This result has implications for practitioners when fitting and assessing the success of high Dk/t hydrogel lenses.

Three-dimensional quadrupole lenses made with permanent magnets

International Nuclear Information System (INIS)

Ivanov, A.S.

1984-01-01

The performance of accelerator systems with quadrupole magnets can be improved by using permanent magnets in quadrupole lenses. This requires better methods for treating the three-dimensional nature of the magnetic fields and the nonlinear characteristics of the magnets. A numerical method is described for simulating three-dimensional magnetic fields and used to analyze quadrupole lenses and doublets with permanent magnets. The results, which are confirmed experimentally, indicate that both the quadrupole magnetic gradient and the effective field length are changed in permanent-magnet quadrupole lenses when the pole lengths and the gap between the lenses are varied while the other characteristics of the magnets remain unchanged

Quantum Spin Lenses in Atomic Arrays

Directory of Open Access Journals (Sweden)

A. W. Glaetzle

2017-09-01

Full Text Available We propose and discuss quantum spin lenses, where quantum states of delocalized spin excitations in an atomic medium are focused in space in a coherent quantum process down to (essentially single atoms. These can be employed to create controlled interactions in a quantum light-matter interface, where photonic qubits stored in an atomic ensemble are mapped to a quantum register represented by single atoms. We propose Hamiltonians for quantum spin lenses as inhomogeneous spin models on lattices, which can be realized with Rydberg atoms in 1D, 2D, and 3D, and with strings of trapped ions. We discuss both linear and nonlinear quantum spin lenses: in a nonlinear lens, repulsive spin-spin interactions lead to focusing dynamics conditional to the number of spin excitations. This allows the mapping of quantum superpositions of delocalized spin excitations to superpositions of spatial spin patterns, which can be addressed by light fields and manipulated. Finally, we propose multifocal quantum spin lenses as a way to generate and distribute entanglement between distant atoms in an atomic lattice array.

Constraining Lyman continuum escape using Machine Learning

Science.gov (United States)

Giri, Sambit K.; Zackrisson, Erik; Binggeli, Christian; Pelckmans, Kristiaan; Cubo, Rubén; Mellema, Garrelt

2018-05-01

The James Webb Space Telescope (JWST) will observe the rest-frame ultraviolet/optical spectra of galaxies from the epoch of reionization (EoR) in unprecedented detail. While escaping into the intergalactic medium, hydrogen-ionizing (Lyman continuum; LyC) photons from the galaxies will contribute to the bluer end of the UV slope and make nebular emission lines less prominent. We present a method to constrain leakage of the LyC photons using the spectra of high redshift (z >~ 6) galaxies. We simulate JWST/NIRSpec observations of galaxies at z =6-9 by matching the fluxes of galaxies observed in the Frontier Fields observations of galaxy cluster MACS-J0416. Our method predicts the escape fraction fesc with a mean absolute error Δfesc ~ 0.14. The method also predicts the redshifts of the galaxies with an error .

Lenses and Perception: Investigations with Light

Science.gov (United States)

Akcay, Hakan

2005-01-01

The main goals of these activities are to help students learn how a convex lens can serve as a magnifying lens and how light travels and creates images. These explorations will introduce middle school students to different types of lenses and how they work. Students will observe and describe how lenses bend light that passes through them and how…

X-ray lenses with large aperture

International Nuclear Information System (INIS)

Simon, Markus

2010-01-01

Up to now, most X-ray imaging setups are based on absorption contrast imaging. There is a demand for focused X-rays in many X-ray analysis applications, either to increase the resolution of an imaging system, or, to reduce the time effort of an experiment through higher photon flux. For photon energies higher than 15 keV refractive X-ray optics are more efficient in comparison to non-refractive X-ray optics. The aim of this work was to develop X-ray lenses with large apertures and high transparency. By increasing the number of refracting surfaces while removing unnecessary lens material such lenses have been developed. Utilizing this approach the overall beam deflection angle is large with respect to the lens material it propagates through and so the transparency of the lens is increased. Within this work, X-ray lenses consisting of several thousands of prisms with an edge length in the range of micrometers have been developed and fabricated by deep X-ray lithography. Deep X-ray lithography enables high precision microstrucures with smooth sidewalls and large aspect ratios. The aperture of high-transparency X-ray lenses made this way is greater than 1 mm. They are suitable for photon energies in the range of 8 keV to 24 keV and offer a focal width of smaller than 10 μm at a transparency of around 40%. Furthermore, rolled X-ray lenses have been developed, that are made out of a microstructured polyimide film, which is cut according to the requirements regarding focal length and photon energy. The microstructured film is fabricated by molding, using an anisotropically etched silicon wafer as molding tool. Its mean roughness is in the range of nanometers. The film features prismatic structures, its surface topology is similar to an asparagus field. The measured diameter of the point focus was 18 μm to 31 μm, the calculated opticla efficiency was 37%. Future work will concentrate on increasing the aspect ratio of Prism Lenses and on increasing the rolling accuracy

Discovery of a Transient U-Band Dropout in a Lyman Break Survey: A Tidally Disrupted Star at z=3.3?

Science.gov (United States)

Stern, Daniel; van Dokkum, P. G.; Nugent, Peter; Sand, D. J.; Ellis, R. S.; Sullivan, Mark; Bloom, J. S.; Frail, D. A.; Kneib, J.-P.; Koopmans, L. V. E.; Treu, Tommaso

2004-09-01

We report the discovery of a transient source in the central regions of galaxy cluster A267. The object, which we call ``PALS-1,'' was found in a survey aimed at identifying highly magnified Lyman break galaxies in the fields of intervening rich clusters. At discovery, the source had Un>24.7 (2 σ AB), g=21.96+/-0.12, and very blue g-r and r-i colors; i.e., PALS-1 was a ``U-band dropout,'' characteristic of star-forming galaxies and quasars at z~3. However, 3 months later the source had faded by more than 3 mag. Further observations showed a continued decline in luminosity, to R>26.4 at 7 months after discovery. Although the apparent brightness suggests a supernova at roughly the cluster redshift, we show that the photometry and light curve argue against any known type of supernova at any redshift. The spectral energy distribution and location near the center of a galaxy cluster are consistent with the hypothesis that PALS-1 is a gravitationally lensed transient at z~3.3. If this interpretation is correct, the source is magnified by a factor of 4-7, and two counterimages are predicted. Our lens model predicts that there are time delays between the three images of 1-10 yr and that we have witnessed the final occurrence of the transient. The intense luminosity (MAB~-23.5 after correcting for lensing) and blue UV continuum (implying T>~50,000 K) argue that the source may have been a flare resulting from the tidal disruption of a star by a 106-108 Msolar black hole. Regardless of its physical nature, PALS-1 highlights the importance of monitoring regions of high magnification in galaxy clusters for distant time-varying phenomena. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California.

Performance Characterization of the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) CCD Cameras

Science.gov (United States)

Joiner, R. K.; Kobayashi, K.; Winebarger, A. R.; Champey, P. R.

2014-12-01

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding rocket instrument which is currently being developed by NASA's Marshall Space Flight Center (MSFC) and the National Astronomical Observatory of Japan (NAOJ). The goal of this instrument is to observe and detect the Hanle effect in the scattered Lyman-Alpha UV (121.6nm) light emitted by the Sun's Chromosphere to make measurements of the magnetic field in this region. In order to make accurate measurements of this effect, the performance characteristics of the three on-board charge-coupled devices (CCDs) must meet certain requirements. These characteristics include: quantum efficiency, gain, dark current, noise, and linearity. Each of these must meet predetermined requirements in order to achieve satisfactory performance for the mission. The cameras must be able to operate with a gain of no greater than 2 e-/DN, a noise level less than 25e-, a dark current level which is less than 10e-/pixel/s, and a residual non-linearity of less than 1%. Determining these characteristics involves performing a series of tests with each of the cameras in a high vacuum environment. Here we present the methods and results of each of these performance tests for the CLASP flight cameras.

Comparison between liquid and solid tunable focus lenses

International Nuclear Information System (INIS)

Santiago-Alvarado, A; Cruz-Martinez, V M; Vazquez-Montiel, S; Munoz-Lopez, J; Diaz-Gonzalez, G; Campos-Garcia, M

2011-01-01

Nowadays more reports in the use of tunable lenses are reported, it is due to the benefits they offer in optical systems design. A tunable lens is an optical system that can focus on a range of positions by changing dynamically one of its geometric parameters. There are several types of tunable lenses, the most known types are the liquid, the solid elastic, with variable refractive index, and lenses that use a dielectric medium. This paper presents the analysis and opto-mechanical design of two tunable lenses, a liquid lens and another Solid Elastic Lens (SEL). Both lenses are made in mounting aluminium and polydimethylsiloxane (PDMS) as refractor medium, the liquid lens use two elastic membranes containing a liquid medium between them while the SEL only use PDMS material as body of the lens (medium refractor). We describe the opto-mechanical performance of both types of lens highlighting the main features of each. Finally, results of a opto-functional comparison between these prototypes are showed.

Planck 2013 results. XVII. Gravitational lensing by large-scale structure

CERN Document Server

Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Basak, S.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Dechelette, T.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Dickinson, C.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Ensslin, T.A.; Eriksen, H.K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Ho, S.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lavabre, A.; Lawrence, C.R.; Leahy, J.P.; Leonardi, R.; Leon-Tavares, J.; Lesgourgues, J.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Pullen, A.R.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubino-Martin, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; White, M.; White, S.D.M.; Yvon, D.; Zacchei, A.; Zonca, A.

2014-01-01

On the arcminute angular scales probed by Planck, the CMB anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this effect, detecting lensing independently in the 100, 143, and 217GHz frequency bands with an overall significance of greater than 25sigma. We use the temperature-gradient correlations induced by lensing to reconstruct a (noisy) map of the CMB lensing potential, which provides an integrated measure of the mass distribution back to the CMB last-scattering surface. Our lensing potential map is significantly correlated with other tracers of mass, a fact which we demonstrate using several representative tracers of large-scale structure. We estimate the power spectrum of the lensing potential, finding generally good agreement with expectations from the best-fitting LCDM model for the Planck temperature power spectrum, showing that this measurement at z=1100 correctly predicts the properties of the lower-redshift, later-time structures which source the lensing ...

Gravitational lensing by spinning and radially moving lenses

International Nuclear Information System (INIS)

Sereno, M.

2002-01-01

The effect of currents of mass on bending of light rays is considered in the weak field regime. Following Fermat's principle and the standard theory of gravitational lensing, we derive the gravito-magnetic correction to time delay function and deflection angle caused by a geometrically-thin lens. The cases of both rotating and shifting deflectors are discussed

Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers

Science.gov (United States)

Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

2018-05-01

Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (H I; having column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}), which extend significantly beyond the redshift-space location of the absorber. We measure this effect as a function of the column density of the HCD absorbers and redshift by measuring three-dimensional (3D) flux power spectra in cosmological hydrodynamical simulations from the Illustris project. Survey pipelines exclude regions containing the largest damping wings. We find that, even after this procedure, there is a scale-dependent correction to the 3D Lyman-alpha forest flux power spectrum from residual contamination. We model this residual using a simple physical model of the HCD absorbers as linearly biased tracers of the matter density distribution, convolved with their Voigt profiles and integrated over the column density distribution function. We recommend the use of this model over existing models used in data analysis, which approximate the damping wings as top-hats and so miss shape information in the extended wings. The simple `linear Voigt model' is statistically consistent with our simulation results for a mock residual contamination up to small scales (|k| account for the effect of the highest column density absorbers on the smallest scales (e.g. |k| > 0.4 h Mpc^{-1} for small damped Lyman-alpha absorbers; HCD absorbers with N(H I) ˜ 10^{21} atoms cm^{-2}). However, these systems are in any case preferentially removed from survey data. Our model is appropriate for an accurate analysis of the baryon acoustic oscillations feature. It is additionally essential for reconstructing the full shape of the 3D flux power spectrum.

Plasma lenses for SLAC Final Focus Test facility

International Nuclear Information System (INIS)

Betz, D.; Cline, D.; Joshi, C.; Rajagopalan, S.; Rosenzweig, J.; Su, J.J.; Williams, R.; Chen, P.; Gundersen, M.; Katsouleas, T.; Norem, J.

1991-01-01

A collaborative group of accelerator and plasma physicists and engineers has formed with an interest in exploring the use of plasma lenses to meet the needs of future colliders. Analytic and computational models of plasma lenses are briefly reviewed and several design examples for the SLAC Final Focus Test Beam are presented. The examples include discrete, thick, and adiabatic lenses. A potential plasma source with desirable lens characteristics is presented

Influence of protein deposition on bacterial adhesion to contact lenses.

Science.gov (United States)

Subbaraman, Lakshman N; Borazjani, Roya; Zhu, Hua; Zhao, Zhenjun; Jones, Lyndon; Willcox, Mark D P

2011-08-01

The aim of the study is to determine the adhesion of Gram positive and Gram negative bacteria onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials with and without lysozyme, lactoferrin, and albumin coating. Four lens types (three SH-balafilcon A, lotrafilcon B, and senofilcon A; one CH-etafilcon A) were coated with lysozyme, lactoferrin, or albumin (uncoated lenses acted as controls) and then incubated in Staphylococcus aureus (Saur 31) or either of two strains of Pseudomonas aeruginosa (Paer 6294 and 6206) for 24 h at 37 °C. The total counts of the adhered bacteria were determined using the H-thymidine method and viable counts by counting the number of colony-forming units on agar media. All three strains adhered significantly lower to uncoated etafilcon A lenses compared with uncoated SH lenses (p 0.05). Lactoferrin coating on lenses increased binding (total and viable counts) of Saur 31 (p lenses showed significantly higher total counts (p lenses. Albumin coating of lenses increased binding (total and viable counts) of all three strains (p lenses does not possess antibacterial activity against certain bacterial strains, whereas lactoferrin possess an antibacterial effect against strains of P. aeruginosa.

GALEX-SELECTED LYMAN BREAK GALAXIES AT z {approx} 2: COMPARISON WITH OTHER POPULATIONS

Energy Technology Data Exchange (ETDEWEB)

Haberzettl, L.; Williger, G. [Department of Physics and Astronomy, University of Louisville, Louisville KY 20492 (United States); Lehnert, M. D. [GEPI, Observatoire de Paris, UMR 8111 du CNRS, 5 Place Jules Janssen, 92195 Meudon (France); Nesvadba, N. [Institut d' Astrophysique Spatiale, CNRS, Universite Paris-Sud, Bat. 120-121, 91405 Orsay (France); Davies, L. [Department of Physics, H H Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom)

2012-01-20

We present results of a search for bright Lyman break galaxies (LBGs) at 1.5 {<=} z {<=} 2.5 in the GOODS-S field using an NUV-dropout technique in combination with color selection. We derived a sample of 73 LBG candidates. We compare our selection efficiencies to BM/BX and BzK methods (techniques solely based on ground-based data sets), and find the NUV data to provide greater efficiency for selecting star-forming galaxies. We estimate LBG candidate ages, masses, star formation rates, and extinction from fitting PEGASE synthesis evolution models. We find that about 20% of our LBG candidates are comparable to infrared-luminous LBGs or submillimeter galaxies which are thought to be precursors of massive elliptical galaxies today. Overall, we can show that although BM/BX and BzK methods do identify star-forming galaxies at z {approx} 2, the sample they provide biases against those star-forming galaxies which are more massive and contain sizeable red stellar populations. A true Lyman break criterion at z {approx} 2 is therefore more directly comparable to the populations found at z {approx} 3, which does contain a red fraction.

GALEX-SELECTED LYMAN BREAK GALAXIES AT z ∼ 2: COMPARISON WITH OTHER POPULATIONS

International Nuclear Information System (INIS)

Haberzettl, L.; Williger, G.; Lehnert, M. D.; Nesvadba, N.; Davies, L.

2012-01-01

We present results of a search for bright Lyman break galaxies (LBGs) at 1.5 ≤ z ≤ 2.5 in the GOODS-S field using an NUV-dropout technique in combination with color selection. We derived a sample of 73 LBG candidates. We compare our selection efficiencies to BM/BX and BzK methods (techniques solely based on ground-based data sets), and find the NUV data to provide greater efficiency for selecting star-forming galaxies. We estimate LBG candidate ages, masses, star formation rates, and extinction from fitting PEGASE synthesis evolution models. We find that about 20% of our LBG candidates are comparable to infrared-luminous LBGs or submillimeter galaxies which are thought to be precursors of massive elliptical galaxies today. Overall, we can show that although BM/BX and BzK methods do identify star-forming galaxies at z ∼ 2, the sample they provide biases against those star-forming galaxies which are more massive and contain sizeable red stellar populations. A true Lyman break criterion at z ∼ 2 is therefore more directly comparable to the populations found at z ∼ 3, which does contain a red fraction.

Visual performance with sport-tinted contact lenses in natural sunlight.

Science.gov (United States)

Erickson, Graham B; Horn, Fraser C; Barney, Tyler; Pexton, Brett; Baird, Richard Y

2009-05-01

The use of tinted and clear contact lenses (CLs) in all aspects of life is becoming a more popular occurrence, particularly in athletic activities. This study broadens previous research regarding performance-tinted CLs and their effects on measures of visual performance. Thirty-three subjects (14 male, 19 female) were fitted with clear B&L Optima 38, 50% visible light transmission Amber and 36% visible light transmission Gray-Green Nike Maxsight CLs in an individualized randomized sequence. Subjects were dark-adapted with welding goggles before testing and in between subtests involving a Bailey-Lovie chart and the Haynes Distance Rock test. The sequence of testing was repeated for each lens modality. The Amber and Gray-Green lenses enabled subjects to recover vision faster in bright sunlight compared with clear lenses. Also, subjects were able to achieve better visual recognition in bright sunlight when compared with clear lenses. Additionally, the lenses allowed the subjects to alternate fixation between a bright and shaded target at a more rapid rate in bright sunlight as compared with clear lenses. Subjects preferred both the Amber and Gray-Green lenses over clear lenses in the bright and shadowed target conditions. The results of the current study show that Maxsight Amber and Gray-Green lenses provide better contrast discrimination in bright sunlight, better contrast discrimination when alternating between bright and shaded target conditions, better speed of visual recovery in bright sunlight, and better overall visual performance in bright and shaded target conditions compared with clear lenses.

Haro 11: Where is the Lyman Continuum Source?

Energy Technology Data Exchange (ETDEWEB)

Keenan, Ryan P.; Oey, M. S. [Department of Astronomy, University of Michigan, 1085 South University Avenue, Ann Arbor, MI 48109 (United States); Jaskot, Anne E. [Department of Astronomy, Smith College, Northampton, MA 01063 (United States); James, Bethan L. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)

2017-10-10

Identifying the mechanism by which high-energy Lyman continuum (LyC) photons escaped from early galaxies is one of the most pressing questions in cosmic evolution. Haro 11 is the best known local LyC-leaking galaxy, providing an important opportunity to test our understanding of LyC escape. The observed LyC emission in this galaxy presumably originates from one of the three bright, photoionizing knots known as A, B, and C. It is known that Knot C has strong Ly α emission, and Knot B hosts an unusually bright ultraluminous X-ray source, which may be a low-luminosity active galactic nucleus. To clarify the LyC source, we carry out ionization-parameter mapping (IPM) by obtaining narrow-band imaging from the Hubble Space Telescope WFC3 and ACS cameras to construct spatially resolved ratio maps of [O iii]/[O ii] emission from the galaxy. IPM traces the ionization structure of the interstellar medium and allows us to identify optically thin regions. To optimize the continuum subtraction, we introduce a new method for determining the best continuum scale factor derived from the mode of the continuum-subtracted, image flux distribution. We find no conclusive evidence of LyC escape from Knots B or C, but instead we identify a high-ionization region extending over at least 1 kpc from Knot A. This knot shows evidence of an extremely young age (≲1 Myr), perhaps containing very massive stars (>100 M {sub ⊙}). It is weak in Ly α , so if it is confirmed as the LyC source, our results imply that LyC emission may be independent of Ly α emission.

The Intergalactic Medium as a Cosmological Tool

Energy Technology Data Exchange (ETDEWEB)

Viel, Matteo, E-mail: viel@oats.inaf.i [INAF - Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, I-34131 Trieste (Italy); INFN/National Institute for Nuclear Physics, Via Valerio 2, I-34127 Trieste (Italy)

2009-10-15

In this talk I will review the capabilities of high-resolution (UVES and Keck) and low resolution (Sloan Digital Sky Survey - SDSS) quasar (QSO) Lyman-alpha absorption spectra as cosmological tools to probe the dark matter distribution in the high redshift universe. I will first summarize the results in terms of cosmological parameters and then discuss consistency with the parameters derived from other large scale structure observable such as the Cosmic Microwave Background (CMB) and weak lensing surveys. When the Lyman-alpha forest data are combined with CMB data and the weak lensing results of the z-COSMOS survey the constraints are: sigma{sub 8}=0.800+-0.023, n{sub s}=0.971+-0.011OMEGA{sub m}=0.247+-0.016 (1-sigma error bars), in perfect agreement with the CMB results of WMAP year five alone. I will briefly address the importance of Lyman-alpha for constraining the neutrino mass fraction. Furthermore, I will present constraints on the mass of warm dark matter (WDM) particles derived from the Lyman-alpha flux power spectrum of 55 high-resolution HIRES Lyman-alpha forest spectra at 2.0=1.2keV (2sigma) if the WDM consists of early decoupled thermal relics and m{sub WDM}>=5.6keV (2sigma) for sterile neutrinos. Adding the SDSS Lyman-alpha flux power spectrum at 2.2=4keV and m{sub WDM}>=28keV (2sigma) for thermal relics and sterile neutrinos. These results improve previous findings by a factor two and are currently the tightest constraints on the coldness of cold dark matter. Finally, I will discuss: i) recent results for a mixture of cold and warm dark matter and the constraints for sterile neutrinos as dark matter candidates in a physically motivated framework (resonant production); ii) perspectives of cross-correlating the Lyman-alpha forest with convergence maps of the cosmic microwave background; iii) fitting of the flux probability distribution function.

Gravitational Lensing from a Spacetime Perspective

Directory of Open Access Journals (Sweden)

Perlick Volker

2004-09-01

Full Text Available The theory of gravitational lensing is reviewed from a spacetime perspective, without quasi-Newtonian approximations. More precisely, the review covers all aspects of gravitational lensing where light propagation is described in terms of lightlike geodesics of a metric of Lorentzian signature. It includes the basic equations and the relevant techniques for calculating the position, the shape, and the brightness of images in an arbitrary general-relativistic spacetime. It also includes general theorems on the classification of caustics, on criteria for multiple imaging, and on the possible number of images. The general results are illustrated with examples of spacetimes where the lensing features can be explicitly calculated, including the Schwarzschild spacetime, the Kerr spacetime, the spacetime of a straight string, plane gravitational waves, and others.

Nanofocusing parabolic refractive x-ray lenses

International Nuclear Information System (INIS)

Schroer, C.G.; Kuhlmann, M.; Hunger, U.T.; Guenzler, T.F.; Kurapova, O.; Feste, S.; Frehse, F.; Lengeler, B.; Drakopoulos, M.; Somogyi, A.; Simionovici, A.S.; Snigirev, A.; Snigireva, I.; Schug, C.; Schroeder, W.H.

2003-01-01

Parabolic refractive x-ray lenses with short focal distance can generate intensive hard x-ray microbeams with lateral extensions in the 100 nm range even at a short distance from a synchrotron radiation source. We have fabricated planar parabolic lenses made of silicon that have a focal distance in the range of a few millimeters at hard x-ray energies. In a crossed geometry, two lenses were used to generate a microbeam with a lateral size of 380 nm by 210 nm at 25 keV in a distance of 42 m from the synchrotron radiation source. Using diamond as the lens material, microbeams with a lateral size down to 20 nm and below are conceivable in the energy range from 10 to 100 keV

The z~4 Lyman Break Galaxies: Colors and Theoretical Predictions

Science.gov (United States)

Idzi, Rafal; Somerville, Rachel; Papovich, Casey; Ferguson, Henry C.; Giavalisco, Mauro; Kretchmer, Claudia; Lotz, Jennifer

2004-01-01

We investigate several fundamental properties of z~4 Lyman break galaxies by comparing observations with the predictions of a semianalytic model based on the cold dark matter theory of hierarchical structure formation. We use a sample of B435-dropouts from the Great Observatories Origins Deep Survey and complement the Advanced Camera for Surveys optical B435, V606, i775, and z850 data with the Very Large Telescope Infrared Spectrometer and Array Camera J, H, and Ks observations. We extract B435-dropouts from our semianalytic mock catalog using the same color criteria and magnitude limits that were applied to the observed sample. We find that the i775-Ks colors of the model-derived and observed B435-dropouts are in good agreement. However, we find that the i775-z850 colors differ significantly, indicating perhaps that either too little dust or an incorrect extinction curve has been used. Motivated by the reasonably good agreement between the model and observed data, we present predictions for the stellar masses, star formation rates, and ages for the z~4 Lyman break sample. We find that according to our model, the color selection criteria used to select our z~4 sample surveys 67% of all galaxies at this epoch down to z850Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. Based on observations collected at the European Southern Observatory, Chile (ESO programmes 168.A-0485, 64.0-0643, 66.A-0572, and 68.A-0544).

Contact Lenses for Color Blindness.

Science.gov (United States)

Badawy, Abdel-Rahman; Hassan, Muhammad Umair; Elsherif, Mohamed; Ahmed, Zubair; Yetisen, Ali K; Butt, Haider

2018-06-01

Color vision deficiency (color blindness) is an inherited genetic ocular disorder. While no cure for this disorder currently exists, several methods can be used to increase the color perception of those affected. One such method is the use of color filtering glasses which are based on Bragg filters. While these glasses are effective, they are high cost, bulky, and incompatible with other vision correction eyeglasses. In this work, a rhodamine derivative is incorporated in commercial contact lenses to filter out the specific wavelength bands (≈545-575 nm) to correct color vision blindness. The biocompatibility assessment of the dyed contact lenses in human corneal fibroblasts and human corneal epithelial cells shows no toxicity and cell viability remains at 99% after 72 h. This study demonstrates the potential of the dyed contact lenses in wavelength filtering and color vision deficiency management. © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Corneal erosions, bacterial contamination of contact lenses, and microbial keratitis.

Science.gov (United States)

Willcox, Mark D P; Naduvilath, Thomas J; Vaddavalli, Pravin K; Holden, Brien A; Ozkan, Jerome; Zhu, Hua

2010-11-01

To estimate the rate of corneal erosion coupled with gram-negative bacterial contamination of contact lenses and compare this with the rate of microbial keratitis (MK) with contact lenses. The rate of corneal erosion and contact lens contamination by gram-negative bacteria were calculated from several prospective trials. These rates were used to calculate the theoretical rate of corneal erosion happening at the same time as wearing a contact lens contaminated with gram-negative bacteria. This theoretical rate was then compared with the rates of MK reported in various epidemiological and clinical trials. Corneal erosions were more frequent during extended wear (0.6-2.6% of visits) compared with daily wear (0.01-0.05% of visits). No corneal erosions were observed for lenses worn on a daily disposable basis. Contamination rates for lenses worn on a daily disposable basis were the lowest (2.4%), whereas they were the highest for low Dk lenses worn on an extended wear basis (7.1%). The estimated rate of corneal erosions occurring at the same time as wearing lenses contaminated with gram-negative bacteria was the lowest during daily wear of low Dk lenses (1.56/10,000 [95% CI: 0.23-10.57]) and the highest during extended wear of high Dk lenses (38.55/10,000 [95% CI: 24.77-60.04]). These rates were similar in magnitude to the rates reported for MK of different hydrogel lenses worn on differing wear schedules. The coincidence of corneal erosions during lens wear with gram-negative bacterial contamination of lenses may account for the relative incidence of MK during lens wear with different lens materials and modes of use.

DYNAMIC SPECTRAL MAPPING OF INTERSTELLAR PLASMA LENSES

Energy Technology Data Exchange (ETDEWEB)

Tuntsov, Artem V.; Walker, Mark A. [Manly Astrophysics, 3/22 Cliff Street, Manly 2095 (Australia); Koopmans, Leon V. E. [Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, NL-9700 AV Groningen (Netherlands); Bannister, Keith W.; Stevens, Jamie; Johnston, Simon [CSIRO Astronomy and Space Science, P.O. Box 76, Epping NSW 1710 (Australia); Reynolds, Cormac; Bignall, Hayley E., E-mail: Artem.Tuntsov@manlyastrophysics.org, E-mail: Mark.Walker@manlyastrophysics.org, E-mail: koopmans@astro.rug.nl [International Centre for Radio Astronomy Research—Curtin University, Perth (Australia)

2016-02-01

Compact radio sources sometimes exhibit intervals of large, rapid changes in their flux density, due to lensing by interstellar plasma crossing the line of sight. A novel survey program has made it possible to discover these “Extreme Scattering Events” (ESEs) in real time, resulting in a high-quality dynamic spectrum of an ESE observed in PKS 1939–315. Here we present a method for determining the column-density profile of a plasma lens, given only the dynamic radio spectrum of the lensed source, under the assumption that the lens is either axisymmetric or totally anisotropic. Our technique relies on the known, strong frequency dependence of the plasma refractive index in order to determine how points in the dynamic spectrum map to positions on the lens. We apply our method to high-frequency (4.2–10.8 GHz) data from the Australia Telescope Compact Array of the PKS 1939–315 ESE. The derived electron column-density profiles are very similar for the two geometries we consider, and both yield a good visual match to the data. However, the fit residuals are substantially above the noise level, and deficiencies are evident when we compare the predictions of our model to lower-frequency (1.6–3.1 GHz) data on the same ESE, thus motivating future development of more sophisticated inversion techniques.

Gravitational lenses and the cosmological evolution of quasars

International Nuclear Information System (INIS)

Avni, Y.

1981-01-01

A heuristic model for the effect of gravitational lenses on the apparent cosmological evolution of quasars is considered. The model satisfies the requirement of average flux conservation and has no net mean amplification. This requirement is shown to be numerically important in studying the effect. On the basis of the values of the evolution indicators calculated from the model, it is concluded that it is premature to assert that lensing plays an important role in affecting the apparent evolution. A qualitative, model independent observational test for the effect is suggested. The test estimates the distances where lensing is dominant. An application of this test to a complete sample of quasars indicates that lensing cannot completely account for the apparent evolution, except in an extreme situation

Optical and visual performance of aspheric soft contact lenses.

Science.gov (United States)

Efron, Suzanne; Efron, Nathan; Morgan, Philip B

2008-03-01

This study was conducted to investigate whether aspheric design soft contact lenses reduce ocular aberrations and result in better visual acuity and subjective appreciation of clinical performance compared with spherical soft contact lenses. A unilateral, double-masked, randomized and controlled study was undertaken in which ocular aberrations and high and low contrast logMAR visual acuity were measured on myopic subjects who wore aspheric design (Biomedics 55 Evolution, CooperVision) and spherical design (Biomedics 55, CooperVision) soft contact lenses. Ten subjects who had about -2.00 D myopia wore -2.00 D lenses and 10 subjects who had about -5.00 D myopia wore -5.00 D lenses. Measurements were made under photopic and mesopic lighting conditions. Subjects were invited to grade comfort, vision in photopic and mesopic conditions, and overall impression with the two lens types on 100 unit visual analogue scales. There was no significant difference in high contrast or low contrast visual acuity between the two lens designs of either power under photopic or mesopic conditions. Both lens designs displayed lower levels of spherical aberration compared with the "no lens" condition under photopic and mesopic light levels (p designs. There were no statistically significant differences in subjective appreciation of clinical performance between lens designs or lens powers. At least with respect to the brand of lenses tested, the fitting of aspheric design soft contact lenses does not result in superior visual acuity, aberration control, or subjective appreciation compared with equivalent spherical design soft contact lenses.

[IOP measurement through frequent-replacement soft contact lenses].

Science.gov (United States)

Touboul, J

2008-07-01

Intraocular pressure (IOP) can be measured through soft contact lenses with an air-puff tonometer. These measurements seemed accurate for low-power negative lenses. For positive soft contact lenses, IOP is overestimated. The measurement of IOP through a soft contact lens is acceptable in clinical practice only for glaucoma screening. In glaucomatous patients or patients with ocular hypertension, IOP measurements should be performed without a contact lens. The main technique for IOP measurement remains Goldmann applanation tonometry.

A gravitationally lensed quasar discovered in OGLE

Science.gov (United States)

Kostrzewa-Rutkowska, Zuzanna; Kozłowski, Szymon; Lemon, Cameron; Anguita, T.; Greiner, J.; Auger, M. W.; Wyrzykowski, Ł.; Apostolovski, Y.; Bolmer, J.; Udalski, A.; Szymański, M. K.; Soszyński, I.; Poleski, R.; Pietrukowicz, P.; Skowron, J.; Mróz, P.; Ulaczyk, K.; Pawlak, M.

2018-05-01

We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the ˜670deg2 area encompassing the Magellanic Clouds. The source was selected as one of ˜60 `red W1 - W2' mid-infrared objects from WISE and having a significant amount of variability in OGLE for both two (or more) nearby sources. This is the first detection of a gravitational lens, where the discovery is made `the other way around', meaning we first measured the time delay between the two lensed quasar images of -132 Technology Telescope spectra. The spectral energy distribution (SED) fitting with the fixed source redshift provided the estimate of the lensing galaxy redshift of z ≈ 0.9 ± 0.2 (90 per cent CL), while its type is more likely to be elliptical (the SED-inferred and lens-model stellar mass is more likely present in ellipticals) than spiral (preferred redshift by the lens model).

Bacterial adherence to extended wear soft contact lenses

International Nuclear Information System (INIS)

Aswad, M.I.; John, T.; Barza, M.; Kenyon, K.; Baum, J.

1990-01-01

The authors studied the adherence of Pseudomonas aeruginosa and Staphylococcus aureus to extended wear soft contact lenses (EWSCLs) with and without focal deposits using both a radiolabeling technique and electron microscopy. P. aeruginosa showed significant adherence to contact lenses in vitro. In contrast, S. aureus failed to show significant adherence to contact lenses in vitro (i.e., the radioactive uptake was not significantly above background). The extent of adherence of Pseudomonas was proportional to the number of focal deposits on the lenses. Results of electron microscopic examination showed the bacteria to be adherent primarily to large focal deposits (greater than or equal to 150 microns). There was no pseudomonal adherence to the small focal deposits (less than or equal to 50 microns) and little adherence to the areas in between the focal deposits. The authors hypothesize that worn lenses, especially those with large focal deposits, serve as a vehicle for the transport of P. aeruginosa to the cornea. This hypothesis could be a partial explanation for the high incidence of keratitis caused by P. aeruginosa in EWSCL patients

Identification of Microorganisms Isolated From Counterfeit and Unapproved Decorative Contact Lenses.

Science.gov (United States)

Land, Adrian D; Penno, Katie L; Brzezinski, Jennifer L

2018-03-01

All contact lenses (corrective/noncorrective) are considered Class II or Class III medical devices under the Federal Food, Drug, and Cosmetic Act, which also states that contact lenses can only be obtained with a prescription. The Forensic Chemistry Center of the US Food & Drug Administration has examined over 300 decorative, noncorrective contact lenses obtained without a prescription. Our observations indicate that 60% of the counterfeit lenses and 27% of the unapproved lenses examined were positive for microbial contamination. Twenty-nine different brands of noncorrective contact lenses were examined, and 48% of them had at least one sample positive for microbial contamination. Each microorganism was further identified using DNA sequencing. Contaminated contact lenses are associated with numerous health risks, including ocular infections and conjunctivitis leading to permanent visual impairment or blindness. These results support the contention that acquiring contact lenses without a prescription is a considerable threat to consumer health and safety. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Stationary nonimaging lenses for solar concentration.

Science.gov (United States)

Kotsidas, Panagiotis; Chatzi, Eleni; Modi, Vijay

2010-09-20

A novel approach for the design of refractive lenses is presented, where the lens is mounted on a stationary aperture and the Sun is tracked by a moving solar cell. The purpose of this work is to design a quasi-stationary concentrator by replacing the two-axis tracking of the Sun with internal motion of the miniaturized solar cell inside the module. Families of lenses are designed with a variation of the simultaneous multiple surface technique in which the sawtooth genetic algorithm is implemented to optimize the geometric variables of the optic in order to produce high fluxes for a range of incidence angles. Finally, we show examples of the technique for lenses with 60° and 30° acceptance half-angles, with low to medium attainable concentrations.

Comparison of the effectiveness of contemporary ophthalmic lenses against β radiation

International Nuclear Information System (INIS)

Dunlap, J.H.; Harvey, P.W.; Schwing, R.L.

1977-01-01

As part of a study intended to identify the lens material and type that provides maximum eye protection against beta radiation, the effectiveness of contemporary ophthalmic lenses has been evaluated. From the calculations and measurements presented it is evident that safety glasses with crown glass ophthalmic lenses afford the eye the greatest protection against beta radiation, whereas street glasses with plastic ophthalmic lenses afford the eye very little protection. It is to be noted that glass street lenses (approximately 2.2 mm thick) provide greater protection than plastic safety lenses (approximately 3.5 mm thick). A warning is given against the use of safety lenses containing a large percentage of thorium. (U.K.)

Non-Gaussian information from weak lensing data via deep learning

Science.gov (United States)

Gupta, Arushi; Matilla, José Manuel Zorrilla; Hsu, Daniel; Haiman, Zoltán

2018-05-01

Weak lensing maps contain information beyond two-point statistics on small scales. Much recent work has tried to extract this information through a range of different observables or via nonlinear transformations of the lensing field. Here we train and apply a two-dimensional convolutional neural network to simulated noiseless lensing maps covering 96 different cosmological models over a range of {Ωm,σ8} . Using the area of the confidence contour in the {Ωm,σ8} plane as a figure of merit, derived from simulated convergence maps smoothed on a scale of 1.0 arcmin, we show that the neural network yields ≈5 × tighter constraints than the power spectrum, and ≈4 × tighter than the lensing peaks. Such gains illustrate the extent to which weak lensing data encode cosmological information not accessible to the power spectrum or even other, non-Gaussian statistics such as lensing peaks.

CMB lensing constraints on dark energy and modified gravity scenarios

International Nuclear Information System (INIS)

Calabrese, Erminia; Cooray, Asantha; Martinelli, Matteo; Melchiorri, Alessandro; Pagano, Luca; Slosar, Anze; Smoot, George F.

2009-01-01

Weak gravitational lensing leaves a characteristic imprint on the cosmic microwave background temperature and polarization angular power spectra. Here, we investigate the possible constraints on the integrated lensing potential from future cosmic microwave background angular spectra measurements expected from Planck and EPIC. We find that Planck and EPIC will constrain the amplitude of the integrated projected potential responsible for lensing at 6% and 1% level, respectively, with very little sensitivity to the shape of the lensing potential. We discuss the implications of such a measurement in constraining dark energy and modified gravity scalar-tensor theories. We then discuss the impact of a wrong assumption on the weak lensing potential amplitude on cosmological parameter inference.

Cross-correlation of gravitational lensing from DES Science Verification data with SPT and Planck lensing

Energy Technology Data Exchange (ETDEWEB)

Kirk, D.; Omori, Y.; Benoit-Lévy, A.; Cawthon, R.; Chang, C.; Larsen, P.; Amara, A.; Bacon, D.; Crawford, T. M.; Dodelson, S.; Fosalba, P.; Giannantonio, T.; Holder, G.; Jain, B.; Kacprzak, T.; Lahav, O.; MacCrann, N.; Nicola, A.; Refregier, A.; Sheldon, E.; Story, K. T.; Troxel, M. A.; Vieira, J. D.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Becker, M. R.; Benson, B. A.; Bernstein, G. M.; Bernstein, R. A.; Bleem, L. E.; Bonnett, C.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carlstrom, J. E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Nichol, R. C.; Ogando, R.; Plazas, A. A.; Reichardt, C. L.; Roodman, A.; Rozo, E.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Simard, G.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Wechsler, R. H.; Weller, J.

2016-03-10

We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg$^{2}$ of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of $z_{\\rm med} {\\sim} 0.7$, while the CMB lensing kernel is broad and peaks at $z{\\sim}2$. The resulting cross-correlation is maximally sensitive to mass fluctuations at $z{\\sim}0.44$. Assuming the Planck 2015 best-fit cosmology, the amplitude of the DES$\\times$SPT cross-power is found to be $A = 0.88 \\pm 0.30$ and that from DES$\\times$Planck to be $A = 0.86 \\pm 0.39$, where $A=1$ corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of $2.9 \\sigma$ and $2.2 \\sigma$ respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photometric redshift uncertainty and CMB lensing systematics. Significant intrinsic alignment of galaxy shapes would increase the cross-correlation signal inferred from the data; we calculate a value of $A = 1.08 \\pm 0.36$ for DES$\\times$SPT when we correct the observations with a simple IA model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation, given the size of the statistical uncertainties and the significant impact of systematic errors, particularly IAs. We provide forecasts for the expected signal-to-noise of the combination of the five-year DES survey and SPT-3G.

Occlusion properties of prosthetic contact lenses for the treatment of amblyopia.

Science.gov (United States)

Collins, Randall S; McChesney, Megan E; McCluer, Craig A; Schatz, Martha P

2008-12-01

The efficacy of opaque contact lenses as occlusion therapy for amblyopia has been established in the literature. Prosthetic contact lenses use similar tints to improve cosmesis in scarred or deformed eyes and may be an alternative in occlusion therapy. To test this idea, we determined the degree of vision penalization elicited by prosthetic contact lenses and their effect on peripheral fusion. We tested 19 CIBA Vision DuraSoft 3 Prosthetic soft contact lenses with varying iris prints, underprints, and opaque pupil sizes in 10 volunteers with best-corrected Snellen distance visual acuity of 20/20 or better in each eye. Snellen visual acuity and peripheral fusion using the Worth 4-Dot test at near were measured on each subject wearing each of the 19 lenses. Results were analyzed with 3-factor analysis of variance. Mean visual acuity through the various lenses ranged from 20/79 to 20/620. Eight lenses allowed preservation of peripheral fusion in 50% or more of the subjects tested. Iris print pattern and opaque pupil size were significant factors in determining visual acuity (p occlusion with prosthetic contact lenses a viable therapy for amblyopia. The degree of penalization can be varied and different iris print patterns and pupil sizes, using peripheral fusion, can be preserved with some lenses. Prosthetic contact lenses can be more cosmetically appealing and more tolerable than other amblyopia treatment modalities. These factors may improve compliance in occlusion therapy.

Direct probe of dark energy through gravitational lensing effect

Energy Technology Data Exchange (ETDEWEB)

He, Hong-Jian [T. D. Lee Institute, and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Zhang, Zhen, E-mail: hjhe@tsinghua.edu.cn, E-mail: zh.zhang@pku.edu.cn [Center for High Energy Physics, Peking University, Beijing 100871 (China)

2017-08-01

We show that gravitational lensing can provide a direct method to probe the nature of dark energy at astrophysical scales. For lensing system as an isolated astrophysical object, we derive the dark energy contribution to gravitational potential as a repulsive power-law term, containing a generic equation of state parameter w . We find that it generates w -dependent and position-dependent modification to the conventional light orbital equation of w =−1. With post-Newtonian approximation, we compute its direct effect for an isolated lensing system at astrophysical scales and find that the dark energy force can deflect the path of incident light rays. We demonstrate that the dark-energy-induced deflection angle Δα{sub DE}∝ M {sup (1+1/3} {sup w} {sup )} (with 1+1/3 w > 0), which increases with the lensing mass M and consistently approaches zero in the limit M → 0. This effect is distinctive because dark energy tends to diffuse the rays and generates concave lensing effect . This is in contrast to the conventional convex lensing effect caused by both visible and dark matter. Measuring such concave lensing effect can directly probe the existence and nature of dark energy. We estimate this effect and show that the current gravitational lensing experiments are sensitive to the direct probe of dark energy at astrophysical scales. For the special case w =−1, our independent study favors the previous works that the cosmological constant can affect light bending, but our prediction qualitatively and quantitatively differ from the literature, including our consistent realization of Δα{sub DE} → 0 (under 0 M → ) at the leading order.

Aspheric lenses for terahertz imaging.

Science.gov (United States)

Lo, Yat Hei; Leonhardt, Rainer

2008-09-29

We present novel designs for aspheric lenses used in terahertz (THz) imaging. As different surfaces result in different beam shaping properties and in different losses from reflection and absorption, the resultant imaging resolution (i.e. the focal spot size) depends critically on the design approach. We evaluate the different lens designs using Kirchhoff's scalar diffraction theory, and test the predictions experimentally. We also show that our lenses can achieve sub-wavelength resolution. While our lens designs are tested with THz radiation, the design considerations are applicable also to other regions of the electro-magnetic spectrum.

Analysis of coronal H I Lyman alpha measurements from a rocket flight on 1979 April 13

Science.gov (United States)

Withbroe, G. L.; Kohl, J. L.; Weiser, H.; Noci, G.; Munro, R. H.

1982-01-01

It is noted that measurements of the profiles of resonantly scattered hydrogen Lyman-alpha coronal radiation have been used in determining hydrogen kinetic temperatures from 1.5 to 4 solar radii from sun center in a quiet region of the corona. Proton temperatures derived using the line widths decrease with height from 2.6 x 10 to the 6th K at 1.5 solar radii to 1.2 x 10 to the 6th K at 4 solar radii. These measurements, together with temperatures for lower heights determined from earlier Skylab and eclipse data, suggest that there is a maximum in the quiet coronal proton temperature at about 1.5 solar radii. Comparison of measured Lyman-alpha intensities with those calculated using a representative model for the radial variation of the coronal electron density yields information on the magnitude of the electron temperature gradient and suggests that the solar wind flow was subsonic for distances less than 4 solar radii.

Management of complications associated with lathe-cut soft contact lenses.

Science.gov (United States)

Freeman, M I

1979-06-01

At the present time, nine lathe-cut lenses are FDA approved and commercially available in the United States. Complications of lathe-cut soft contact lenses cover a wide spectrum of problems. Five significant complications of lathe-cut lenses and their prevention and therapeutic management are discussed.

Interpreting HST observations with simulations of reionization: the ionizing photon budget and the decline of Lyman-alpha emission in z>6 dropouts

Science.gov (United States)

D'Aloisio, Anson

2017-08-01

In recent years, HST surveys such as CANDELS, HUDF, BoRG/HIPPIES, ERS, and the Frontier Fields, have made possible the first robust measurements of the rest-frame UV luminosity function of z =6-10 galaxies, spanning much of the redshift range over which reionization likely occurred. These measurements provide an estimate of the galactic ionizing photon output, addressing the critical question of whether these galaxies could have reionized the Universe. In addition, follow-up spectroscopy has measured the fraction of these galaxies that show Lyman-alpha emission. Interestingly, a dramatic decrease in this fraction above z 6 has been observed, and this evolution has (controversially) been interpreted as evidence that much of reionization happened over z=6-8 (as intergalactic neutral gas leads to large damping wings that scatter the Lyman-alpha line). The clumpiness of the IGM and how it self shields to ionizing photons impacts whether the observed population of galaxies can reionize the Universe, as well as the interpretation of the evolving Lyman-alpha emitter fraction. We propose to run fully coupled radiative-hydrodynamics simulations that are the first to resolve the evaporation of small structures by passing ionization fronts and, hence, to accurately assess the level of clumpiness and self-shielding from the IGM. Our study will nail down the clumping factor used to assess whether the observed population of galaxies can drive reionization, and it will address whether neutral self-shielding clumps in recently reionized regions can scatter galaxies' Lyman-alpha lines.

Coatings and Tints of Spectacle Lenses

Directory of Open Access Journals (Sweden)

H. Zeki Büyükyıldız

2012-10-01

Full Text Available Spectacle lenses are made of mineral or organic (plastic materials. Various coatings and tints are applied to the spectacle lenses according to the characteristic of the lens material, and for the personal needs and cosmetic purpose. The coatings may be classified in seven groups: 1 Anti-reflection coatings, 2 Hard coatings, 3 Clean coat, 4 Mirror coatings, 5 Color tint coating (one of coloring processes, 6 Photochromic coating (one of photochromic processes, and 7 Anti-fog coatings. Anti-reflection coatings reduce unwanted reflections from the lens surfaces and increase light transmission. Hard coatings are applied for preventing the plastic lens surface from scratches and abrasion. Hard coatings are not required for the mineral lenses due to their hardness. Clean coat makes the lens surface smooth and hydrophobic. Thus, it prevents the adherence of dust, tarnish, and dirt particles on the lens surface. Mirror coatings are applied onto the sunglasses for cosmetic purpose. Color tinted and photochromic lenses are used for sun protection and absorption of the harmful UV radiations. Anti-fog coatings make the lens surface hydrophilic and prevent the coalescence of tiny water droplets on the lens surface that reduces light transmission. (Turk J Ophthalmol 2012; 42: 359-69

Protein deposition and its effect on bacterial adhesion to contact lenses.

Science.gov (United States)

Omali, Negar Babaei; Zhu, Hua; Zhao, Zhenjun; Willcox, Mark D P

2013-06-01

Bacterial adhesion to contact lenses is believed to be the initial step for the development of several adverse reactions that occur during lens wear such as microbial keratitis. This study examined the effect of combinations of proteins on the adhesion of bacteria to contact lenses. Unworn balafilcon A and senofilcon A lenses were soaked in commercially available pure protein mixtures to achieve the same amount of various proteins as found ex vivo. These lenses were then exposed to Pseudomonas aeruginosa and Staphylococcus aureus. Following incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. The possible effect of proteins on bacterial growth was investigated by incubating bacteria in medium containing protein. Although there was a significant (p lenses soaked in the lysozyme/lactoferrin combination, the protein adhered to lenses did not alter the adhesion of any other strains of P. aeruginosa or S. aureus (p > 0.05). Growth of S. aureus 031 (p 0.05). Adsorption of amounts of lysozyme and lactoferrin or lipocalin equivalent to those extracted from worn contact lenses did not affect the adhesion of most strains of S. aureus or P. aeruginosa to lens surfaces.

Tear exchange and contact lenses: a review.

Science.gov (United States)

Muntz, Alex; Subbaraman, Lakshman N; Sorbara, Luigina; Jones, Lyndon

2015-01-01

Tear exchange beneath a contact lens facilitates ongoing fluid replenishment between the ocular surface and the lens. This exchange is considerably lower during the wear of soft lenses compared with rigid lenses. As a result, the accumulation of tear film debris and metabolic by-products between the cornea and a soft contact lens increases, potentially leading to complications. Lens design innovations have been proposed, but no substantial improvement in soft lens tear exchange has been reported. Researchers have determined post-lens tear exchange using several methods, notably fluorophotometry. However, due to technological limitations, little remains known about tear hydrodynamics around the lens and, to-date, true tear exchange with contact lenses has not been shown. Further knowledge regarding tear exchange could be vital in aiding better contact lens design, with the prospect of alleviating certain adverse ocular responses. This article reviews the literature to-date on the significance, implications and measurement of tear exchange with contact lenses. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Phosphorylcholine impairs susceptibility to biofilm formation of hydrogel contact lenses.

Science.gov (United States)

Selan, Laura; Palma, Stefano; Scoarughi, Gian Luca; Papa, Rosanna; Veeh, Richard; Di Clemente, Daniele; Artini, Marco

2009-01-01

To compare silicone-hydrogel, poly(2-hydroxyethyl methacrylate) (pHEMA), and phosphorylcholine-coated (PC-C) contact lenses in terms of their susceptibility to biofilm formation by Staphylococcus epidermidis and Pseudomonas aeruginosa. Laboratory investigation. Biofilm formation on colonized test lenses was evaluated with confocal microscopy and in vitro antibiotic susceptibility assays. The results of the latter assays were compared with those performed on planktonic cultures of the same organism. For both microorganisms, sessile colonies on silicone-hydrogel and pHEMA lenses displayed lower antibiotic susceptibility than their planktonic counterparts. In contrast, the susceptibility of cultures growing on PC-C lenses was comparable with that for planktonic cultures. In particular, minimum inhibitory concentration for Tazocin (piperacillin plus tazobactam; Wyeth Pharmaceuticals, Aprilia, Italy; S. epidermidis) and gentamicin (P. aeruginosa) was identical, either in the presence of PC-C support or in planktonic cultures (Tazocin, aeruginosa) was two-fold higher for PC-C lenses (0.4 mug/ml) with respect to planktonic cultures (0.2 mug/ml). Confocal microscopy of lenses colonized for 24 hours with P. aeruginosa green fluorescent protein-expressing cells revealed a sessile colonization on silicone-hydrogel lens and a few isolated bacterial cells scattered widely over the surface of the PC-C lens. An increase in antibiotic susceptibility of bacterial cultures was associated with diminished bacterial adhesion. Our results indicate that PC-C lenses seem to be more resistant than silicone-hydrogel and pHEMA lenses to bacterial adhesion and colonization. This feature may facilitate their disinfection.

Parabolic crossed planar polymeric x-ray lenses

Science.gov (United States)

Nazmov, V.; Reznikova, E.; Mohr, J.; Saile, V.; Vincze, L.; Vekemans, B.; Bohic, S.; Somogyi, A.

2011-01-01

The principles of design and manufacturing of the polymer planar x-ray lenses focusing in one and two directions, as well as the peculiarities of optical behaviors and the results of the lens test are reported in this paper. The methods of electron and deep x-ray lithography used in lens manufacturing allow the manufacture of ten or more x-ray lenses on one substrate; the lenses show focal lengths down to several centimeters for photon energies between 5 and 40 keV. The measured focus size was 105 nm for a linear lens with an intensity gain of about 407, and 300 × 770 nm for a crossed lens with an intensity gain of 6470.

Physical and morphological properties of z ~ 3 Lyman break galaxies: dependence on Lyα line emission

Science.gov (United States)

Pentericci, L.; Grazian, A.; Scarlata, C.; Fontana, A.; Castellano, M.; Giallongo, E.; Vanzella, E.

2010-05-01

Aims: We investigate the physical and morphological properties of Lyman break galaxies (LBGs) at redshift ~2.5 to ~3.5, to determine if and how they depend on the nature and strength of the Lyα emission. Methods: We selected U-dropout galaxies from the z-detected GOODS-MUSIC catalog by adapting the classical Lyman break criteria on the GOODS filter set. We kept only those galaxies with spectroscopic confirmation, mainly from VIMOS and FORS public observations. Using the full multi-wavelength 14-bands information (U to IRAC), we determined the physical properties of the galaxies through a standard spectral energy distribution fitting procedure with the updated Charlot & Bruzual (2009) templates. We also added other relevant observations of the GOODS field, i.e. the 24 μm observations from Spitzer/MIPS and the 2 MSec Chandra X-ray observations. Finally, using non parametric diagnostics (Gini, Concentration, Asymmetry, M20 and ellipticity), we characterized the rest-frame UV morphologies of the galaxies. We then analyzed how these physical and morphological properties correlate with the presence of the Lyα emission line in the optical spectra. Results: We find that unlike at higher redshift, the dependence of physical properties on the Lyα line is milder: galaxies without Lyα in emission tend to be more massive and dustier than the rest of the sample, but all other parameters, ages, star formation rates (SFR), X-ray emission and UV morphology do not depend strongly on the presence of the Lyα emission. A simple scenario where all LBGs have intrinsically high Lyα emission, but where the dust and neutral hydrogen content (which shapes the final appearance of the Lyα) depend on the mass of the galaxies, is able to reproduce the majority of the observed properties at z˜3. Some modification might be needed to account for the observed evolution of these properties with cosmic epoch, which is also discussed.

Exploring cosmic origins with CORE: Gravitational lensing of the CMB

Science.gov (United States)

Challinor, A.; Allison, R.; Carron, J.; Errard, J.; Feeney, S.; Kitching, T.; Lesgourgues, J.; Lewis, A.; Zubeldía, Í.; Achucarro, A.; Ade, P.; Ashdown, M.; Ballardini, M.; Banday, A. J.; Banerji, R.; Bartlett, J.; Bartolo, N.; Basak, S.; Baumann, D.; Bersanelli, M.; Bonaldi, A.; Bonato, M.; Borrill, J.; Bouchet, F.; Boulanger, F.; Brinckmann, T.; Bucher, M.; Burigana, C.; Buzzelli, A.; Cai, Z.-Y.; Calvo, M.; Carvalho, C.-S.; Castellano, G.; Chluba, J.; Clesse, S.; Colantoni, I.; Coppolecchia, A.; Crook, M.; d'Alessandro, G.; de Bernardis, P.; de Gasperis, G.; De Zotti, G.; Delabrouille, J.; Di Valentino, E.; Diego, J.-M.; Fernandez-Cobos, R.; Ferraro, S.; Finelli, F.; Forastieri, F.; Galli, S.; Genova-Santos, R.; Gerbino, M.; González-Nuevo, J.; Grandis, S.; Greenslade, J.; Hagstotz, S.; Hanany, S.; Handley, W.; Hernandez-Monteagudo, C.; Hervías-Caimapo, C.; Hills, M.; Hivon, E.; Kiiveri, K.; Kisner, T.; Kunz, M.; Kurki-Suonio, H.; Lamagna, L.; Lasenby, A.; Lattanzi, M.; Liguori, M.; Lindholm, V.; López-Caniego, M.; Luzzi, G.; Maffei, B.; Martinez-González, E.; Martins, C. J. A. P.; Masi, S.; Matarrese, S.; McCarthy, D.; Melchiorri, A.; Melin, J.-B.; Molinari, D.; Monfardini, A.; Natoli, P.; Negrello, M.; Notari, A.; Paiella, A.; Paoletti, D.; Patanchon, G.; Piat, M.; Pisano, G.; Polastri, L.; Polenta, G.; Pollo, A.; Poulin, V.; Quartin, M.; Remazeilles, M.; Roman, M.; Rubino-Martin, J.-A.; Salvati, L.; Tartari, A.; Tomasi, M.; Tramonte, D.; Trappe, N.; Trombetti, T.; Tucker, C.; Valiviita, J.; Van de Weijgaert, R.; van Tent, B.; Vennin, V.; Vielva, P.; Vittorio, N.; Young, K.; Zannoni, M.

2018-04-01

Lensing of the cosmic microwave background (CMB) is now a well-developed probe of the clustering of the large-scale mass distribution over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE mission will allow production of a clean map of the lensing deflections over nearly the full-sky. The number of high-S/N modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that will follow from its power spectrum and the cross-correlation with other clustering data. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous measurements of the baryon acoustic oscillation feature in the clustering of galaxies, three times smaller than the minimum total mass allowed by neutrino oscillation measurements. Lensing has applications across many other science goals of CORE, including the search for B-mode polarization from primordial gravitational waves. Here, lens-induced B-modes will dominate over instrument noise, limiting constraints on the power spectrum amplitude of primordial gravitational waves. With lensing reconstructed by CORE, one can "delens" the observed polarization internally, reducing the lensing B-mode power by 60 %. This can be improved to 70 % by combining lensing and measurements of the cosmic infrared background from CORE, leading to an improvement of a factor of 2.5 in the error on the amplitude of primordial gravitational waves compared to no delensing (in the null hypothesis of no primordial B-modes). Lensing measurements from CORE will allow calibration of the halo masses of the tens of thousands of galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. The 19

Are Disposable and Standard Gonioscopy Lenses Comparable?

Science.gov (United States)

Lee, Bonny; Szirth, Bernard C; Fechtner, Robert D; Khouri, Albert S

2017-04-01

Gonioscopy is important in the evaluation and treatment of glaucoma. With increased scrutiny of acceptable sterilization processes for health care instruments, disposable gonioscopy lenses have recently been introduced. Single-time use lenses are theorized to decrease infection risk and eliminate the issue of wear and tear seen on standard, reusable lenses. However, patient care would be compromised if the quality of images produced by the disposable lens were inferior to those produced by the reusable lens. The purpose of this study was to compare the quality of images produced by disposable versus standard gonioscopy lenses. A disposable single mirror lens (Sensor Medical Technology) and a standard Volk G-1 gonioscopy lens were used to image 21 volunteers who were prospectively recruited for the study. Images of the inferior and temporal angles of each subject's left eye were acquired using a slit-lamp camera through the disposable and standard gonioscopy lens. In total, 74 images were graded using the Spaeth gonioscopic system and for clarity and quality. Clarity was scored as 1 or 2 and defined as either (1) all structures perceived or (2) all structures not perceived. Quality was scored as 1, 2, or 3, and defined as (1) all angle landmarks clear and well focused, (2) some angle landmarks clear, others blurred, or (3) angle landmarks could not be ascertained. The 74 images were divided into images taken with the disposable single mirror lens and images taken with the standard Volk G-1 gonioscopy lens. The clarity and quality scores for each of these 2 image groups were averaged and P-values were calculated. Average quality of images produced with the standard lens was 1.46±0.56 compared with 1.54±0.61 for those produced with the disposable lens (P=0.55). Average clarity of images produced with the standard lens was 1.47±0.51 compared with 1.49±0.51 (P=0.90) with the disposable lens. We conclude that there is no significant difference in quality of images

Observations of gravitational lenses

International Nuclear Information System (INIS)

Fort, B.

1990-01-01

During the last tow years a burst of results has come from radio and optical surveys of ''galaxy lenses'' (where the main deflector is a galaxy). These are reviewed. On the other hand, in September 1985 we pointed out a very strange blue ring-like structure on a Charge-Coupled Device image of the cluster of galaxies Abell 370. This turned out to be Einstein arcs discovery. Following this discovery, new observational results have shown that many rich clusters of galaxies can produce numerous arclets: tangentially distorted images of an extremely faint galaxy population probably located at redshift larger than 1. This new class of gravitational lenses proves to be an important observational topic and this will be discussed in the second part of the paper. (author)

Plasma lenses for focusing relativistic electron beams

International Nuclear Information System (INIS)

Govil, R.; Wheeler, S.; Leemans, W.

1997-01-01

The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n p much greater than electron beam density, n b ) or underdense (n p less than 2 n b ). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated

Material properties that predict preservative uptake for silicone hydrogel contact lenses.

Science.gov (United States)

Green, J Angelo; Phillips, K Scott; Hitchins, Victoria M; Lucas, Anne D; Shoff, Megan E; Hutter, Joseph C; Rorer, Eva M; Eydelman, Malvina B

2012-11-01

To assess material properties that affect preservative uptake by silicone hydrogel lenses. We evaluated the water content (using differential scanning calorimetry), effective pore size (using probe penetration), and preservative uptake (using high-performance liquid chromatography with spectrophotometric detection) of silicone and conventional hydrogel soft contact lenses. Lenses grouped similarly based on freezable water content as they did based on total water content. Evaluation of the effective pore size highlighted potential differences between the surface-treated and non-surface-treated materials. The water content of the lens materials and ionic charge are associated with the degree of preservative uptake. The current grouping system for testing contact lens-solution interactions separates all silicone hydrogels from conventional hydrogel contact lenses. However, not all silicone hydrogel lenses interact similarly with the same contact lens solution. Based upon the results of our research, we propose that the same material characteristics used to group conventional hydrogel lenses, water content and ionic charge, can also be used to predict uptake of hydrophilic preservatives for silicone hydrogel lenses. In addition, the hydrophobicity of silicone hydrogel contact lenses, although not investigated here, is a unique contact lens material property that should be evaluated for the uptake of relatively hydrophobic preservatives and tear components.

Microstructured gradient-index lenses for THz photoconductive antennas

Directory of Open Access Journals (Sweden)

Mads Brincker

2016-02-01

Full Text Available A new type of substrate lens for photoconductive antennas (PCA’s based on sub-wavelength microstructuring is presented and studied theoretically by the use of Greens function integral equation methods (GFIEM’s. By etching sub-wavelength trenches into a flat substrate, the effective dielectric constant can be designed to function like a gradient index (GRIN lens. The proposed GRIN substrate lenses have sub-mm dimension, which is smaller than the dimensions of a typical hyper-hemispherical substrate lens (HSL, and could enable fabrication of arrays of closely packed PCA’s with individual lenses integrated directly into the PCA substrate. The performance of different GRIN lenses is compared to a HSL and shown to be comparable with regards to the terahertz radiation extraction efficiency, and it is shown that the collimating properties of these GRIN lenses can be tailored by changing the parameters used for microstructuring.

Comments on the Gravitational lensing Magnification

OpenAIRE

Takashi, HAMANA; Astronomical Institute, Tohoku University

1998-01-01

We rederive a relation between gravitational lensing magnification relative to the standard Friedmann distance and one relative to the Dyer-Roeder distance by investigating the null geodesic deviation equation. We show that the relation comes from a natural consequence of the definition of the lensing magnification matrices and is not based on the averaging of the magnifications, which has conventionally been used to derive it. We therefore conclude that the relation is true for each individu...

Comments on the gravitational lensing magnification

OpenAIRE

Hamana, Takashi

1998-01-01

We rederive a relation between gravitational lensing magnification relative to the standard Friedmann distance and one relative to the Dyer-Roeder distance by investigating the null geodesic deviation equation. We show that the relation comes from a natural consequence of the definition of the lensing magnification matrices and is not based on the averaging of the magnifications, which has conventionally been used to derive it. We therefore conclude that the relation is true for each individu...

Magnetic electron lenses

CERN Document Server

1982-01-01

No single volume has been entirely devoted to the properties of magnetic lenses, so far as I am aware, although of course all the numerous textbooks on electron optics devote space to them. The absence of such a volume, bringing together in­ formation about the theory and practical design of these lenses, is surprising, for their introduction some fifty years ago has created an entirely new family of commercial instruments, ranging from the now traditional transmission electron microscope, through the reflection and transmission scanning microscopes, to co­ lumns for micromachining and microlithography, not to mention the host of experi­ mental devices not available commercially. It therefore seemed useful to prepare an account of the various aspects of mag­ netic lens studies. These divide naturally into the five chapters of this book: the theoretical background, in which the optical behaviour is described and formu­ lae given for the various aberration coefficients; numerical methods for calculat­ ing...

Comparative Evaluation of Ultraviolet and Visible Light Transmittance through Prescriptive Ophthalmic Minus Lenses

Directory of Open Access Journals (Sweden)

Mohammadreza Nazari

2014-06-01

Full Text Available Background: Wearing spectacles is the most common approach in correcting the refractive errors worldwide. Due to harmful effects of overexposure to solar ultraviolet radiations, the usage of multi-layer coatings in ophthalmic lenses has recently been increased. These lenses can reduce the reflections and hence increase the transmission of visible light; they can also decrease the transmission of ultraviolet rays. This study aims to compare the transmission of ultraviolet (A and B and visible rays through coated and uncoated prescriptive ophthalmic plastic lenses.Materials and Methods: In this study, 39 minus non-photochromic multi-coated white plastic single-vision lenses; 9 similar lenses but without any coatings were assessed by spectral transmittancemeter for evaluation of the transmission of visible and ultraviolet rays.Results: The transmission of visible light was 97.9%±1.07% for coated lenses and 93.5%±0.54% for lenses without coating. Ultraviolet-A transmission was 12.15%±8.02% for coated lenses compared to 66.27%±23.92% in lenses without coating. The transmission of ultraviolet-B rays was 1.21%±0.4% and 23.0%±15.97% for lenses with and without coatings, respectively.Conclusion: The transmission of visible light was significantly higher in multi-coated lenses compared to uncoated samples; whereas the transmissions of ultraviolet rays in multi-coated lenses were significantly lower than uncoated ones. Therefore, it is recommended that, except for particular cases, prescribed lenses be equipped with this multi-layer coating.

DETECTION OF LENSING SUBSTRUCTURE USING ALMA OBSERVATIONS OF THE DUSTY GALAXY SDP.81

Energy Technology Data Exchange (ETDEWEB)

Hezaveh, Yashar D.; Mao, Yao-Yuan; Morningstar, Warren; Blandford, Roger D.; Levasseur, Laurence Perreault; Wechsler, Risa H. [Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University, 452 Lomita Mall, Stanford, CA 94305-4085 (United States); Dalal, Neal; Wen, Di; Kemball, Athol; Vieira, Joaquin D. [Astronomy Department, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana IL 61801 (United States); Marrone, Daniel P. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Carlstrom, John E. [Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Fassnacht, Christopher D. [Department of Physics, University of California, One Shields Avenue, Davis, CA 95616 (United States); Holder, Gilbert P. [Department of Physics, McGill University, 3600 Rue University, Montreal, Quebec H3A 2T8 (Canada); Marshall, Philip J. [Kavli Institute for Particle Astrophysics and Cosmology and Department of Particle Physics and Astrophysics, SLAC National Accelerator Laboratory, Menlo Park, CA 94305 (United States); Murray, Norman [CITA, University of Toronto, 60 St. George St., Toronto ON M5S 3H8 (Canada)

2016-05-20

We study the abundance of substructure in the matter density near galaxies using ALMA Science Verification observations of the strong lensing system SDP.81. We present a method to measure the abundance of subhalos around galaxies using interferometric observations of gravitational lenses. Using simulated ALMA observations we explore the effects of various systematics, including antenna phase errors and source priors, and show how such errors may be measured or marginalized. We apply our formalism to ALMA observations of SDP.81. We find evidence for the presence of a M = 10{sup 8.96±0.12} M {sub ⊙} subhalo near one of the images, with a significance of 6.9 σ in a joint fit to data from bands 6 and 7; the effect of the subhalo is also detected in both bands individually. We also derive constraints on the abundance of dark matter (DM) subhalos down to M ∼ 2 × 10{sup 7} M {sub ⊙}, pushing down to the mass regime of the smallest detected satellites in the Local Group, where there are significant discrepancies between the observed population of luminous galaxies and predicted DM subhalos. We find hints of additional substructure, warranting further study using the full SDP.81 data set (including, for example, the spectroscopic imaging of the lensed carbon monoxide emission). We compare the results of this search to the predictions of ΛCDM halos, and find that given current uncertainties in the host halo properties of SDP.81, our measurements of substructure are consistent with theoretical expectations. Observations of larger samples of gravitational lenses with ALMA should be able to improve the constraints on the abundance of galactic substructure.

DETECTION OF LENSING SUBSTRUCTURE USING ALMA OBSERVATIONS OF THE DUSTY GALAXY SDP.81

International Nuclear Information System (INIS)

Hezaveh, Yashar D.; Mao, Yao-Yuan; Morningstar, Warren; Blandford, Roger D.; Levasseur, Laurence Perreault; Wechsler, Risa H.; Dalal, Neal; Wen, Di; Kemball, Athol; Vieira, Joaquin D.; Marrone, Daniel P.; Carlstrom, John E.; Fassnacht, Christopher D.; Holder, Gilbert P.; Marshall, Philip J.; Murray, Norman

2016-01-01

We study the abundance of substructure in the matter density near galaxies using ALMA Science Verification observations of the strong lensing system SDP.81. We present a method to measure the abundance of subhalos around galaxies using interferometric observations of gravitational lenses. Using simulated ALMA observations we explore the effects of various systematics, including antenna phase errors and source priors, and show how such errors may be measured or marginalized. We apply our formalism to ALMA observations of SDP.81. We find evidence for the presence of a M = 10 8.96±0.12 M ⊙ subhalo near one of the images, with a significance of 6.9 σ in a joint fit to data from bands 6 and 7; the effect of the subhalo is also detected in both bands individually. We also derive constraints on the abundance of dark matter (DM) subhalos down to M ∼ 2 × 10 7 M ⊙ , pushing down to the mass regime of the smallest detected satellites in the Local Group, where there are significant discrepancies between the observed population of luminous galaxies and predicted DM subhalos. We find hints of additional substructure, warranting further study using the full SDP.81 data set (including, for example, the spectroscopic imaging of the lensed carbon monoxide emission). We compare the results of this search to the predictions of ΛCDM halos, and find that given current uncertainties in the host halo properties of SDP.81, our measurements of substructure are consistent with theoretical expectations. Observations of larger samples of gravitational lenses with ALMA should be able to improve the constraints on the abundance of galactic substructure.

Consequences of wear interruption for discomfort with contact lenses.

Science.gov (United States)

Papas, Eric B; Tilia, Daniel; Tomlinson, Daniel; Williams, Josh; Chan, Eddy; Chan, Jason; Golebiowski, Blanka

2014-01-01

To establish whether increased end-of-day discomfort during soft contact lens wear is associated with short-term changes occurring to the lens itself. Twenty-seven subjects wore hydrogel lenses (Focus Dailies; Alcon) bilaterally for 10 hours on two separate days. Comfort was reported using 1-100 numerical rating scales (1 = intolerable discomfort, 100 = lens cannot be felt). Day 1 ratings were taken before lens insertion and at 0.05, 5, and 10 hours post-insertion. Day 2 ratings occurred at similar times, but lenses were removed after the 5-hour assessment and either reinserted (n = 14) or newly replaced (n = 12). An additional rating was taken 5 minutes after re-insertion. Wear then continued to the 10-hour point. In a separate study, 24 different subjects repeated these procedures using a silicone hydrogel lens (AirOptix Aqua; Alcon) with wear taking place on 3 days to permit lens replacement to be with existing as well as new lenses in all subjects. For hydrogel lenses, comfort scores (mean ± 95% CI) reported after 10 hours were 79.4 ± 8.3 when lenses were worn un-replaced, compared with 73.2 ± 9.2 for replacement with the existing lens. When replacement was with a brand new lens, the corresponding values were 72.9 ± 10.9 (un-replaced) versus 69.2 ± 12.8 (new lens replacement). For silicone hydrogel lenses, 10-hour comfort was 90.3 ± 3.2 (un-replaced) versus 92.2 ± 2.9 (replacement with existing lens) versus 90.0 ± 3.3 (replacement with new lens). Differences between replacement conditions were not significant in any case (analysis of variance, p > 0.05). Final comfort was not influenced by replacing lenses midway through the wearing period. Comfort decrements experienced by users of these daily contact lenses towards the later part of the wearing period are not caused by changes occurring to the lenses on this time scale. Possible alternative etiological factors include a fatigue-like response in one or more ocular tissues or stimulation of ocular

Electron beams, lenses, and optics. Volume 1

International Nuclear Information System (INIS)

El-Kareh, A.B.; El-Kareh, J.C.J.

1970-01-01

This book treats the ideal case where all lenses are assumed to be free from errors. It presents a thorough mathematical analysis of the electrostatic immersion lens, both symmetrical and asymetrical, and covers the einzel lens and the symmetrical magnetic lens in detail. The authors have obtained data on these lenses by means of a digital computer and present them in tabular form

Aberration characteristics of immersion lenses for LVSEM

International Nuclear Information System (INIS)

Khursheed, Anjam

2002-01-01

This paper investigates the on-axis aberration characteristics of various immersion objective lenses for low voltage scanning electron microscopy (LVSEM). A simple aperture lens model is used to generate smooth axial field distributions. The simulation results show that mixed field electric-magnetic immersion lenses are predicted to have between 1.5 and 2 times smaller aberration limited probe diameters than their pure-field counterparts. At a landing energy of 1 keV, mixed field immersion lenses operating at the vacuum electrical field breakdown limit are predicted to have on-axis aberration coefficients between 50 and 60 μm, yielding an ultimate image resolution of below 1 nm. These aberrations lie in the same range as those for LVSEM systems that employ aberration correctors

Lathe-cut hydrophilic contact lenses: report of 100 clinical cases.

Science.gov (United States)

Espy, J W

1978-10-01

In a review of the literature, it became apparent that there were very few articles describing the advantages, as well as the fitting techniques, of lathe-cut hydrophilic contact lenses. Few practitioners, including those who fit other types of hydrophilic lenses and hard lenses, have had any experience with this lens, and considerable interest has been generated by fragmentary reports of good results. This paper describes in detail the geometry of the first lathe-cut hydrophilic lens approved by the Federal Drug Administration, the fitting methods utilizing trial lenses, and the results of 100 patients successfully fitted.

Large-acceptance diamond planar refractive lenses manufactured by laser cutting.

Science.gov (United States)

Polikarpov, Maxim; Snigireva, Irina; Morse, John; Yunkin, Vyacheslav; Kuznetsov, Sergey; Snigirev, Anatoly

2015-01-01

For the first time, single-crystal diamond planar refractive lenses have been fabricated by laser micromachining in 300 µm-thick diamond plates which were grown by chemical vapour deposition. Linear lenses with apertures up to 1 mm and parabola apex radii up to 500 µm were manufactured and tested at the ESRF ID06 beamline. The large acceptance of these lenses allows them to be used as beam-conditioning elements. Owing to the unsurpassed thermal properties of single-crystal diamond, these lenses should be suitable to withstand the extreme flux densities expected at the planned fourth-generation X-ray sources.

Corrections for gravitational lensing of supernovae: better than average?

OpenAIRE

Gunnarsson, Christofer; Dahlen, Tomas; Goobar, Ariel; Jonsson, Jakob; Mortsell, Edvard

2005-01-01

We investigate the possibility of correcting for the magnification due to gravitational lensing of standard candle sources, such as Type Ia supernovae. Our method uses the observed properties of the foreground galaxies along the lines-of-sight to each source and the accuracy of the lensing correction depends on the quality and depth of these observations as well as the uncertainties in translating the observed luminosities to the matter distribution in the lensing galaxies. The current work i...

Multi-centre evaluation of two daily disposable contact lenses.

Science.gov (United States)

Walker, Jon; Young, Graeme; Hunt, Chris; Henderson, Terri

2007-05-01

To evaluate the clinical performance of two daily disposable contact lenses: 1-DAY ACUVUE (1DA) (etafilcon A, Johnson & Johnson Vision Care) and FOCUS DAILIES with AquaComfort (FD) (nelfilcon A, CIBA Vision, Inc.), which contains a quickly released moisture enhancing agent, polyvinyl alcohol (PVA). This was a 1-week, daily wear, subject-masked, bilateral, parallel group study with subjects randomly assigned to one of two daily disposable soft contact lenses. Subjects were existing soft contact lens wearers in the age range 18-39 years with a spherical refraction between -0.50 and -6.00 D. Subjects were assessed at baseline and after 1 week. Assessments included both subjective (symptoms, wearing time, vision) and objective (lens fit and ocular health) outcomes. Twenty clinical sites enrolled 282 subjects (74% female) of whom 276 (98%) successfully completed the study. Significantly more 1DA wearers reported higher mean comfort scores than with FD (3.95 versus 3.41, respectively, Pdisposable lenses highlight that, although both lenses may be considered as clinically acceptable, these lenses should not be regarded as interchangeable.

Oxygen, water, and sodium chloride transport in soft contact lenses materials.

Science.gov (United States)

Gavara, Rafael; Compañ, Vicente

2017-11-01

Oxygen permeability, diffusion coefficient of the sodium ions and water flux and permeability in different conventional hydrogel (Hy) and silicone-hydrogel (Si-Hy) contact lenses have been measured experimentally. The results showed that oxygen permeability and transmissibility requirements of the lens have been addressed through the use of siloxane containing hydrogels. In general, oxygen and sodium chloride permeability values increased with the water content of the lens but there was a percolation phenomenon from a given value of water uptake mainly in the Si-Hy lenses which appeared to be related with the differences between free water and bound water contents. The increase of ion permeability with water content did not follow a unique trend indicating a possible dependence of the chemical structure of the polymer and character ionic and non-ionic of the lens. Indeed, the salt permeability values for silicone hydrogel contact lenses were one order of magnitude below those of conventional hydrogel contact lenses, which can be explained by a diffusion of sodium ions occurring only through the hydrophilic channels. The increase of the ionic permeability in Si-Hy materials may be due to the confinement of ions in nanoscale water channels involving possible decreased degrees of freedom for diffusion of both water and ions. In general, ionic lenses presented values of ionic permeability and diffusivity higher than most non-ionic lenses. The tortuosity of the ionic lenses is lower than the non-ionic Si-Hy lenses. Frequency 55 and PureVision exhibited the highest water permeability and flux values and, these parameters were greater for ionic Si-Hy lenses than for ionic conventional hydrogel lenses. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2218-2231, 2017. © 2016 Wiley Periodicals, Inc.

The effect of Lyman α self-absorption on population inversions between quantum states 2 and 3 of hydrogen-like ions in recombining plasmas

International Nuclear Information System (INIS)

Tallents, G.J.

1978-01-01

The effect in recombining plasmas of Lyman α self-absorption on quasi-steady-state population inversions between quantum states n = 2 and 3 of hydrogen-like ions is theoretically investigated. It is shown how the electron density range over which population inversion is possible diminishes as Lyman α self-absorption increases. The highest degree of absorption which can be tolerated and still achieve an inversion is shown to occur when the thermal limit corresponds to n approximately equal to 4. The results of the computations are related to the conditions to be found in the expansion plume of laser-produced plasmas. (author)

A most useful manifestation of relativity: gravitational lenses

International Nuclear Information System (INIS)

Falco, Emilio E

2005-01-01

Gravitational lenses are scarce but extraordinary phenomena that yield a very high rate of return on observational investment. Given their scarcity, it is very impressive that since their discovery in the extragalactic realm in 1979, they have had such an enormous impact on our knowledge of the universe. Gravitational lensing is a manifestation of general relativity that has contributed to a great variety of astrophysical and cosmological studies. In the weak-field limit, lensing studies are based on well-established physics and thus offer a direct approach to study many of the currently pressing problems of astrophysics. Examples of these are the significance of dark matter and the age and size of the universe. I present a brief history of gravitational lensing and describe recent developments in fields such as searches for dark matter and studies of galaxy evolution and cosmology. The approach is non-specialized and emphasizes observational results, to reach the widest possible audience

Electron Lenses for the Large Hadron Collider

Energy Technology Data Exchange (ETDEWEB)

Stancari, Giulio [Fermilab; Valishev, Alexander [Fermilab; Bruce, Roderik [CERN; Redaelli, Stefano [CERN; Rossi, Adriana [CERN; Salvachua, Belen [CERN

2014-07-01

Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-by-bunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beam compensation, and for the demonstration of halo scraping with hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. This project is moving towards a technical design in 2014, with the goal to build the devices in 2015-2017, after resuming LHC operations and re-assessing needs and requirements at 6.5 TeV. Because of their electric charge and the absence of materials close to the proton beam, electron lenses may also provide an alternative to wires for long-range beam-beam compensation in LHC luminosity upgrade scenarios with small crossing angles.

Melimine-Coated Antimicrobial Contact Lenses Reduce Microbial Keratitis in an Animal Model.

Science.gov (United States)

Dutta, Debarun; Vijay, Ajay K; Kumar, Naresh; Willcox, Mark D P

2016-10-01

To determine the ability of antimicrobial peptide melimine-coated contact lenses to reduce the incidence of microbial keratitis (MK) in a rabbit model of contact lens wear. In vitro antimicrobial activity of melimine-coated contact lenses was determined against Pseudomonas aeruginosa by viable count and a radiolabeled assay. The amount of lipopolysaccharide (LPS) associated with bacteria bound to melimine-coated and control lenses was determined. Ocular swabs from rabbit eyes were collected for assessment of ocular microflora. A rabbit model for MK was developed that used overnight wear of contact lenses colonized by P. aeruginosa in the absence of a corneal scratch. During lens wear, detailed ocular examinations were performed, and the incidence of MK was investigated. Bacteria associated with worn lenses and infected corneas were determined by viable plate count. Inhibition in viable and total P. aeruginosa adhesion by melimine-coated contact lenses was 3.1 log10 and 0.4 log10, respectively. After colonization, the amount of LPS on lenses was approximately the same with or without melimine. Gram-positive bacteria were found in all the ocular swabs followed by fungus (42%). Melimine-coated lens wear was protective and significantly (odds ratio 10.12; P = 0.012) reduced the incidence of P. aeruginosa-driven MK in the rabbit model. The antimicrobial lenses were associated with significantly (P lenses can produce MK without corneal epithelial defect in an animal model. Melimine-coated contact lenses reduced the incidence of MK associated with P. aeruginosa in vivo. Development of MK requires viable bacteria adherent to contact lenses, and bacterial debris adherent at the lens surface did not cause keratitis.

Recovering the systemic redshift of galaxies from their Lyman-alpha line profile

Science.gov (United States)

Verhamme, A.; Garel, T.; Ventou, E.; Contini, T.; Bouché, N.; Herenz, E. C.; Richard, J.; Bacon, R.; Schmidt, K. B.; Maseda, M.; Marino, R. A.; Brinchmann, J.; Cantalupo, S.; Caruana, J.; Clément, B.; Diener, C.; Drake, A. B.; Hashimoto, T.; Inami, H.; Kerutt, J.; Kollatschny, W.; Leclercq, F.; Patrício, V.; Schaye, J.; Wisotzki, L.; Zabl, J.

2018-04-01

The Lyman alpha (Lyα) line of Hydrogen is a prominent feature in the spectra of star-forming galaxies, usually redshifted by a few hundreds of km s-1 compared to the systemic redshift. This large offset hampers follow-up surveys, galaxy pair statistics and correlations with quasar absorption lines when only Lyα is available. We propose diagnostics that can be used to recover the systemic redshift directly from the properties of the Lyα line profile. We use spectroscopic observations of Lyman-Alpha Emitters (LAEs) for which a precise measurement of the systemic redshift is available. Our sample contains 13 sources detected between z ≈ 3 and z ≈ 6 as part of various Multi Unit Spectroscopic Explorer (MUSE) Guaranteed Time Observations (GTO). We also include a compilation of spectroscopic Lyα data from the literature spanning a wide redshift range (z ≈ 0 - 8). First, restricting our analysis to double-peaked Lyα spectra, we find a tight correlation between the velocity offset of the red peak with respect to the systemic redshift, V_peak^red, and the separation of the peaks. Secondly, we find a correlation between V_peak^red and the full width at half maximum of the Lyα line. Fitting formulas, to estimate systemic redshifts of galaxies with an accuracy of ≤100 km s-1 when only the Lyα emission line is available, are given for the two methods.

The Canada-France deep fields survey-II: Lyman-break galaxies and galaxy clustering at z ~ 3

Science.gov (United States)

Foucaud, S.; McCracken, H. J.; Le Fèvre, O.; Arnouts, S.; Brodwin, M.; Lilly, S. J.; Crampton, D.; Mellier, Y.

2003-10-01

We present a large sample of z ~ 3 U-band dropout galaxies extracted from the Canada-France deep fields survey (CFDF). Our catalogue covers an effective area of ~ 1700 arcmin2 divided between three large, contiguous fields separated widely on the sky. To IAB=24.5, the survey contains 1294 Lyman-break candidates, in agreement with previous measurements by other authors, after appropriate incompleteness corrections have been applied to our data. Based on comparisons with spectroscopic observations and simulations, we estimate that our sample of Lyman-break galaxies is contaminated by stars and interlopers (lower-redshift galaxies) at no more than { ~ } 30%. We find that omega (theta ) is well fitted by a power-law of fixed slope, gamma =1.8, even at small (theta University of Hawaii, and at the Cerro Tololo Inter-American Observatory and Mayall 4-meter Telescopes, divisions of the National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, Inc. under cooperative agreement with the National Science Foundation.

DISCOVERY OF THE LARGEST KNOWN LENSED IMAGES FORMED BY A CRITICALLY CONVERGENT LENSING CLUSTER

International Nuclear Information System (INIS)

Zitrin, Adi; Broadhurst, Tom

2009-01-01

We identify the largest known lensed images of a single spiral galaxy, lying close to the center of the distant cluster MACS J1149.5+2223 (z = 0.544). These images cover a total area of ≅150 mbox '' and are magnified ≅200 times. Unusually, there is very little image distortion, implying that the central mass distribution is almost uniform over a wide area (r ≅ 200 kpc) with a surface density equal to the critical density for lensing, corresponding to maximal lens magnification. Many fainter multiply lensed galaxies are also uncovered by our model, outlining a very large tangential critical curve, of radius r ≅ 170 kpc, posing a potential challenge for the standard LCDM cosmology. Because of the uniform central mass distribution, a particularly clean measurement of the mass of the brightest cluster galaxy is possible here, for which we infer stars contribute most of the mass within a limiting radius of ≅30 kpc, with a mass-to-light ratio of M/L B ≅ 4.5(M/L) sun . This cluster with its uniform and central mass distribution acts analogously to a regular magnifying glass, converging light without distorting the images, resulting in the most powerful lens yet discovered for accessing the faint high-z universe.

A Statistical Study of Multiply Imaged Systems in the Lensing Cluster Abell 68

Science.gov (United States)

Richard, Johan; Kneib, Jean-Paul; Jullo, Eric; Covone, Giovanni; Limousin, Marceau; Ellis, Richard; Stark, Daniel; Bundy, Kevin; Czoske, Oliver; Ebeling, Harald; Soucail, Geneviève

2007-06-01

We have carried out an extensive spectroscopic survey with the Keck and VLT telescopes, targeting lensed galaxies in the background of the massive cluster Abell 68. Spectroscopic measurements are obtained for 26 lensed images, including a distant galaxy at z=5.4. Redshifts have been determined for 5 out of 7 multiple-image systems. Through a careful modeling of the mass distribution in the strongly lensed regime, we derive a mass estimate of 5.3×1014 Msolar within 500 kpc. Our mass model is then used to constrain the redshift distribution of the remaining multiply imaged and singly imaged sources. This enables us to examine the physical properties for a subsample of 7 Lyα emitters at 1.7financial support of the W. M. Keck Foundation. Also based on observations collected at the Very Large Telescope (Antu/UT1 and Melipal/UT3), European Southern Observatory, Paranal, Chile (ESO programs 070.A-0643 and 073.A-0774), the NASA/ESA Hubble Space Telescope (program 8249) obtained at the Space Telescope Science Institute, which is operated by AURA under NASA contract NAS5-26555, and the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

A gravitationally lensed quasar with quadruple images separated by 14.62 arcseconds.

Science.gov (United States)

Inada, Naohisa; Oguri, Masamune; Pindor, Bartosz; Hennawi, Joseph F; Chiu, Kuenley; Zheng, Wei; Ichikawa, Shin-Ichi; Gregg, Michael D; Becker, Robert H; Suto, Yasushi; Strauss, Michael A; Turner, Edwin L; Keeton, Charles R; Annis, James; Castander, Francisco J; Eisenstein, Daniel J; Frieman, Joshua A; Fukugita, Masataka; Gunn, James E; Johnston, David E; Kent, Stephen M; Nichol, Robert C; Richards, Gordon T; Rix, Hans-Walter; Sheldon, Erin Scott; Bahcall, Neta A; Brinkmann, J; Ivezić, Zeljko; Lamb, Don Q; McKay, Timothy A; Schneider, Donald P; York, Donald G

2003-12-18

Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures (that is, clusters of galaxies and even larger assemblies) predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model.

Weak lensing in the Dark Energy Survey

Science.gov (United States)

Troxel, Michael

2016-03-01

I will present the current status of weak lensing results from the Dark Energy Survey (DES). DES will survey 5000 square degrees in five photometric bands (grizY), and has already provided a competitive weak lensing catalog from Science Verification data covering just 3% of the final survey footprint. I will summarize the status of shear catalog production using observations from the first year of the survey and discuss recent weak lensing science results from DES. Finally, I will report on the outlook for future cosmological analyses in DES including the two-point cosmic shear correlation function and discuss challenges that DES and future surveys will face in achieving a control of systematics that allows us to take full advantage of the available statistical power of our shear catalogs.

A cosmic web filament revealed in Lyman-α emission around a luminous high-redshift quasar.

Science.gov (United States)

Cantalupo, Sebastiano; Arrigoni-Battaia, Fabrizio; Prochaska, J Xavier; Hennawi, Joseph F; Madau, Piero

2014-02-06

Simulations of structure formation in the Universe predict that galaxies are embedded in a 'cosmic web', where most baryons reside as rarefied and highly ionized gas. This material has been studied for decades in absorption against background sources, but the sparseness of these inherently one-dimensional probes preclude direct constraints on the three-dimensional morphology of the underlying web. Here we report observations of a cosmic web filament in Lyman-α emission, discovered during a survey for cosmic gas fluorescently illuminated by bright quasars at redshift z ≈ 2.3. With a linear projected size of approximately 460 physical kiloparsecs, the Lyman-α emission surrounding the radio-quiet quasar UM 287 extends well beyond the virial radius of any plausible associated dark-matter halo and therefore traces intergalactic gas. The estimated cold gas mass of the filament from the observed emission-about 10(12.0 ± 0.5)/C(1/2) solar masses, where C is the gas clumping factor-is more than ten times larger than what is typically found in cosmological simulations, suggesting that a population of intergalactic gas clumps with subkiloparsec sizes may be missing in current numerical models.

Magnetic resonance imaging diagnosis of intraocular lenses. Die kernspintomographische Diagnostik der Hinterkammerlinse

Energy Technology Data Exchange (ETDEWEB)

Tosch, U. (Strahlenklinik und Poliklinik, Universitaetsklinik Rudolf Virchow, Berlin (Germany)); Bleckmann, H. (Strahlenklinik und Poliklinik, Universitaetsklinik Rudolf Virchow, Berlin (Germany)); Kaczmarek, U. (Strahlenklinik und Poliklinik, Universitaetsklinik Rudolf Virchow, Berlin (Germany))

1994-09-01

Intraocular lenses were investigated by MRI to obtain information about the quality of this method. In experimental studies, seven lenses of between 0 and 30 diopters were visualized. By MRI it was possible to differentiate the various diameters of lenses. It was not possible to discriminate the material of the intraocular lenses. After these first studies the eyes of two corpses and eight patients were investigated. Because of the resolution of MRI it was possible to tell the diopter of implanted lenses. However, by use of MRI in the regular position, a tilting or decentration of the intraocular lens was demonstrated. (orig.)

Mechanism and computational model for Lyman-α-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

Science.gov (United States)

Louchev, Oleg A.; Bakule, Pavel; Saito, Norihito; Wada, Satoshi; Yokoyama, Koji; Ishida, Katsuhiko; Iwasaki, Masahiko

2011-09-01

We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-α (Ly-α) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-α generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-α radiation generation can achieve a value of ˜5×10-4 which is restricted by the total combined absorption of the fundamental and generated radiation.

Mechanism and computational model for Lyman-{alpha}-radiation generation by high-intensity-laser four-wave mixing in Kr-Ar gas

Energy Technology Data Exchange (ETDEWEB)

Louchev, Oleg A.; Saito, Norihito; Wada, Satoshi [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Bakule, Pavel [STFC, ISIS Facility, Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX (United Kingdom); Yokoyama, Koji [Advanced Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama, 351-0198 (Japan); Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan); Ishida, Katsuhiko; Iwasaki, Masahiko [Advanced Meson Science Laboratory, RIKEN Nishina Center, RIKEN, Wako, Saitama 351-0198 (Japan)

2011-09-15

We present a theoretical model combined with a computational study of a laser four-wave mixing process under optical discharge in which the non-steady-state four-wave amplitude equations are integrated with the kinetic equations of initial optical discharge and electron avalanche ionization in Kr-Ar gas. The model is validated by earlier experimental data showing strong inhibition of the generation of pulsed, tunable Lyman-{alpha} (Ly-{alpha}) radiation when using sum-difference frequency mixing of 212.6 nm and tunable infrared radiation (820-850 nm). The rigorous computational approach to the problem reveals the possibility and mechanism of strong auto-oscillations in sum-difference resonant Ly-{alpha} generation due to the combined effect of (i) 212.6-nm (2+1)-photon ionization producing initial electrons, followed by (ii) the electron avalanche dominated by 843-nm radiation, and (iii) the final breakdown of the phase matching condition. The model shows that the final efficiency of Ly-{alpha} radiation generation can achieve a value of {approx}5x10{sup -4} which is restricted by the total combined absorption of the fundamental and generated radiation.

A simple technique of intraocular lenses explantation for single-piece foldable lenses

Directory of Open Access Journals (Sweden)

Arup Bhaumik

2017-01-01

Full Text Available Foldable intraocular lenses (IOLs are most commonly used in modern-day cataract surgery. Explantation of these IOLs is not frequently encountered, but sometimes extreme situations may demand the same. Commonly explantation is achieved by bisecting the IOL inside the anterior chamber with a cutter and delivering the pieces out one by one. This may require corneal wound extension with associated damage and endothelial loss leading to visual deterioration. We devised a simple, innovative IOL explantation technique utilizing a modified Alcon A cartridge and snare. This can successfully refold the IOL to be explanted inside the eye and deliver it out through the same wound. The device has limitations with very thick optic lenses, multipiece, and silicon IOLs. In conclusion, we describe a simple, innovative, and reproducible technique to explant almost any single piece IOL without compromising the original surgery and yielding very satisfactory outcomes.

Weak lensing probes of modified gravity

International Nuclear Information System (INIS)

Schmidt, Fabian

2008-01-01

We study the effect of modifications to general relativity on large-scale weak lensing observables. In particular, we consider three modified gravity scenarios: f(R) gravity, the Dvali-Gabadadze-Porrati model, and tensor-vector-scalar theory. Weak lensing is sensitive to the growth of structure and the relation between matter and gravitational potentials, both of which will in general be affected by modified gravity. Restricting ourselves to linear scales, we compare the predictions for galaxy-shear and shear-shear correlations of each modified gravity cosmology to those of an effective dark energy cosmology with the same expansion history. In this way, the effects of modified gravity on the growth of perturbations are separated from the expansion history. We also propose a test which isolates the matter-potential relation from the growth factor and matter power spectrum. For all three modified gravity models, the predictions for galaxy and shear correlations will be discernible from those of dark energy with very high significance in future weak lensing surveys. Furthermore, each model predicts a measurably distinct scale dependence and redshift evolution of galaxy and shear correlations, which can be traced back to the physical foundations of each model. We show that the signal-to-noise for detecting signatures of modified gravity is much higher for weak lensing observables as compared to the integrated Sachs-Wolfe effect, measured via the galaxy-cosmic microwave background cross-correlation.

Does correcting astigmatism with toric lenses improve driving performance?

Science.gov (United States)

Cox, Daniel J; Banton, Thomas; Record, Steven; Grabman, Jesse H; Hawkins, Ronald J

2015-04-01

Driving is a vision-based activity of daily living that impacts safety. Because visual disruption can compromise driving safety, contact lens wearers with astigmatism may pose a driving safety risk if they experience residual blur from spherical lenses that do not correct their astigmatism or if they experience blur from toric lenses that rotate excessively. Given that toric lens stabilization systems are continually improving, this preliminary study tested the hypothesis that astigmats wearing toric contact lenses, compared with spherical lenses, would exhibit better overall driving performance and driving-specific visual abilities. A within-subject, single-blind, crossover, randomized design was used to evaluate driving performance in 11 young adults with astigmatism (-0.75 to -1.75 diopters cylinder). Each participant drove a highly immersive, virtual reality driving simulator (210 degrees field of view) with (1) no correction, (2) spherical contact lens correction (ACUVUE MOIST), and (3) toric contact lens correction (ACUVUE MOIST for Astigmatism). Tactical driving skills such as steering, speed management, and braking, as well as operational driving abilities such as visual acuity, contrast sensitivity, and foot and arm reaction time, were quantified. There was a main effect for type of correction on driving performance (p = 0.05). Correction with toric lenses resulted in significantly safer tactical driving performance than no correction (p driving safety from no correction (p = 0.118). Operational tests differentiated corrected from uncorrected performance for both spherical (p = 0.008) and toric (p = 0.011) lenses, but they were not sensitive enough to differentiate toric from spherical lens conditions. Given previous research showing that deficits in these tactical skills are predictive of future real-world collisions, these preliminary data suggest that correcting low to moderate astigmatism with toric lenses may be important to driving safety. Their

Complete super-sample lensing covariance in the response approach

Science.gov (United States)

Barreira, Alexandre; Krause, Elisabeth; Schmidt, Fabian

2018-06-01

We derive the complete super-sample covariance (SSC) of the matter and weak lensing convergence power spectra using the power spectrum response formalism to accurately describe the coupling of super- to sub-survey modes. The SSC term is completely characterized by the survey window function, the nonlinear matter power spectrum and the full first-order nonlinear power spectrum response function, which describes the response to super-survey density and tidal field perturbations. Generalized separate universe simulations can efficiently measure these responses in the nonlinear regime of structure formation, which is necessary for lensing applications. We derive the lensing SSC formulae for two cases: one under the Limber and flat-sky approximations, and a more general one that goes beyond the Limber approximation in the super-survey mode and is valid for curved sky applications. Quantitatively, we find that for sky fractions fsky ≈ 0.3 and a single source redshift at zS=1, the use of the flat-sky and Limber approximation underestimates the total SSC contribution by ≈ 10%. The contribution from super-survey tidal fields to the lensing SSC, which has not been included in cosmological analyses so far, is shown to represent about 5% of the total lensing covariance on multipoles l1,l2 gtrsim 300. The SSC is the dominant off-diagonal contribution to the total lensing covariance, making it appropriate to include these tidal terms and beyond flat-sky/Limber corrections in cosmic shear analyses.

Photometric redshift requirements for lens galaxies in galaxy-galaxy lensing analyses

Science.gov (United States)

Nakajima, R.; Mandelbaum, R.; Seljak, U.; Cohn, J. D.; Reyes, R.; Cool, R.

2012-03-01

Weak gravitational lensing is a valuable probe of galaxy formation and cosmology. Here we quantify the effects of using photometric redshifts (photo-z) in galaxy-galaxy lensing, for both sources and lenses, both for the immediate goal of using galaxies with photo-z as lenses in the Sloan Digital Sky Survey (SDSS) and as a demonstration of methodology for large, upcoming weak lensing surveys that will by necessity be dominated by lens samples with photo-z. We calculate the bias in the lensing mass calibration as well as consequences for absolute magnitude (i.e. k-corrections) and stellar mass estimates for a large sample of SDSS Data Release 8 (DR8) galaxies. The redshifts are obtained with the template-based photo-z code ZEBRA on the SDSS DR8 ugriz photometry. We assemble and characterize the calibration samples (˜9000 spectroscopic redshifts from four surveys) to obtain photometric redshift errors and lensing biases corresponding to our full SDSS DR8 lens and source catalogues. Our tests of the calibration sample also highlight the impact of observing conditions in the imaging survey when the spectroscopic calibration covers a small fraction of its footprint; atypical imaging conditions in calibration fields can lead to incorrect conclusions regarding the photo-z of the full survey. For the SDSS DR8 catalogue, we find σΔz/(1+z)= 0.096 and 0.113 for the lens and source catalogues, with flux limits of r= 21 and 21.8, respectively. The photo-z bias and scatter is a function of photo-z and template types, which we exploit to apply photo-z quality cuts. By using photo-z rather than spectroscopy for lenses, dim blue galaxies and L* galaxies up to z˜ 0.4 can be used as lenses, thus expanding into unexplored areas of parameter space. We also explore the systematic uncertainty in the lensing signal calibration when using source photo-z, and both lens and source photo-z; given the size of existing training samples, we can constrain the lensing signal calibration (and

Achromatic Cooling Channel with Li Lenses

Energy Technology Data Exchange (ETDEWEB)

Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

2002-04-29

A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.

Effect of phospholipid deposits on adhesion of bacteria to contact lenses.

Science.gov (United States)

Babaei Omali, Negar; Proschogo, Nicholas; Zhu, Hua; Zhao, Zhenjun; Diec, Jennie; Borazjani, Roya; Willcox, Mark D P

2012-01-01

Protein and lipid deposits on contact lenses may contribute to clinical complications. This study examined the effect of phospholipids on the adhesion of bacteria to contact lenses. Worn balafilcon A (n = 11) and senofilcon A (n = 11) were collected after daily wear and phospholipids were extracted in chloroform:methanol. The amount of phospholipid was measured by electrospray ionization mass spectrometry. Unworn lenses soaked in phospholipids were exposed to Pseudomonas aeruginosa and Staphylococcus aureus. After 18 h incubation, the numbers of P. aeruginosa or S. aureus that adhered to the lenses were measured. Phospholipid was tested for possible effects on bacterial growth. A broad range of sphingomyelins (SM) and phosphatidylcholines (PC) were detected from both types of worn lenses. SM (16:0) (m/z 703) and PC (34:2) (m/z 758) were the major phospholipids detected in the lens extracts. Phospholipids did not alter the adhesion of any strain of P. aeruginosa or S. aureus (p > 0.05). Phospholipids (0.1 mg/mL) showed no effect on the growth of P. aeruginosa 6294 or S. aureus 031. Phospholipids adsorb/absorb to contact lenses during wear, however, the major types of phospholipids adsorbed to lenses do not alter bacterial adhesion or growth.

Study of interplanetary hydrogen from Lyman alpha emission and absorption determination

International Nuclear Information System (INIS)

Cazes, Serge.

1979-09-01

The purpose of the work submitted in this paper is to contribute to the study of interplanetary hydrogen from Lyman alpha emission and absorption measurements, carried out on board the D2A, OSO-8 and Copernicus satellites. This study, which was undertaken from the D2A satellite, moved us to study the interplanetary environment as from observations made from the following experiments placed on board the OSO-8 and Copernicus satellites. The experiment set up on board the OSO-8 satellite made it possible to obtain the profile of the solar alpha Lyman emission. An absorption profile was observed for the first time on these profiles and this made it possible to attribute them to interplanetary hydrogen and enabled us to make a direct and local determination of the solar ionization rate. - The spectrometer set up on board Copernicus made it possible to obtain the emission spectrum of the interplanetary environment at the same time as the geocorona. The overall velocity of the interplanetary environment was deduced from the Doppler shift between the two spectra. In the first part, the principle of the REA and POLAR experiments is recalled but only the REA experiment is described in detail, particularly the problems arising from the construction and calibration of the cell. In the second part, a study of the interplanetary environment made from the D2A determinations is presented in synthesized form. On the other hand, the study to which theses initial results led us is presented in detail. Finally, in the third part, the results obtained by means of the OSO-8 and Copernicus satellites are given [fr

Dimensional stability of lathe cut C.A.B. lenses.

Science.gov (United States)

Pearson, R M

1978-08-01

Measurements of the back central optical radius in the course of 336 hours of hydration of lathe cut corneal lenses disclosed changes in curvature which were more rapid and of greater magnitude than those previously reported for poly (methyl methacrylate) lenses.

Measuring the total and baryonic mass profiles of the very massive CASSOWARY 31 strong lens

DEFF Research Database (Denmark)

Grillo, Claudio; Christensen, L.; Gallazzi, A.

2013-01-01

We investigate the total and baryonic mass distributions in deflector number 31 (CSWA 31) of the Cambridge And Sloan Survey Of Wide ARcs in the skY (CASSOWARY). We confirm spectroscopically a four-image lensing system at redshift 1.4870 with Very Large Telescope/X-shooter observations. The lensed...... find that the CSWA 31 deflector has properties suggesting it to be among the most distant and massive fossil systems studied so far. The unusually strong central dark matter dominance and the possible fossil nature of this system render it an interesting target for detailed tests of cosmological models...

Generation of continuous coherent radiation at Lyman-alpha and 1S-2P Spectroscopy of atomic hydrogen

NARCIS (Netherlands)

Pahl, A.; Fendel, P.; Henrich, B.R.; Walz, J.; Hansch, T.W.; Eikema, K.S.E.

2005-01-01

Continuous coherent radiation from wavelengths from 121 to 123 nm in the vacuum ultraviolet (VUV) was generated by four-wave sum-frequency mixing in mercury vapor. A yield of 20 nW at Lyman-alpha (121.57 nm) was achieved. We describe the experimental setup in detail and present a calculation of the

Gravitational lensing in plasmic medium

Energy Technology Data Exchange (ETDEWEB)

Bisnovatyi-Kogan, G. S., E-mail: gkogan@iki.rssi.ru; Tsupko, O. Yu., E-mail: tsupko@iki.rssi.ru [Russian Academy of Sciences, Space Research Institute (Russian Federation)

2015-07-15

The influence of plasma on different effects of gravitational lensing is reviewed. Using the Hamiltonian approach for geometrical optics in a medium in the presence of gravity, an exact formula for the photon deflection angle by a black hole (or another body with a Schwarzschild metric) embedded in plasma with a spherically symmetric density distribution is derived. The deflection angle in this case is determined by the mutual combination of different factors: gravity, dispersion, and refraction. While the effects of deflection by the gravity in vacuum and the refractive deflection in a nonhomogeneous medium are well known, the new effect is that, in the case of a homogeneous plasma, in the absence of refractive deflection, the gravitational deflection differs from the vacuum deflection and depends on the photon frequency. In the presence of a plasma nonhomogeneity, the chromatic refractive deflection also occurs, so the presence of plasma always makes gravitational lensing chromatic. In particular, the presence of plasma leads to different angular positions of the same image if it is observed at different wavelengths. It is discussed in detail how to apply the presented formulas for the calculation of the deflection angle in different situations. Gravitational lensing in plasma beyond the weak deflection approximation is also considered.

Fresnel's Lighthouse Lenses

Science.gov (United States)

Greenslade, Thomas B., Jr.

2007-01-01

One of the rewards of walking up the scores of steps winding around the inside of the shaft of a lighthouse is turning inward and examining the glass optical system. This arrangement of prisms, lenses, and reflectors is used to project the light from a relatively small source in a beam that can be seen far at sea.

CLASH

DEFF Research Database (Denmark)

Coe, D.; Postman, M.; Bradley, L.

2013-01-01

We present a candidate for the most distant galaxy known to date with a photometric redshift of z = 10.7 (95% confidence limits; with z <9.5 galaxies of known types ruled out at 7.2s). This J-dropout Lyman break galaxy, named MACS0647-JD, was discovered as part of the Cluster Lensing and Supernov...

Flat liquid crystal diffractive lenses with variable focus and magnification

Science.gov (United States)

Valley, Pouria

Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera

Planck 2013 results. XVII. Gravitational lensing by large-scale structure

DEFF Research Database (Denmark)

Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.

2013-01-01

On the arcminute angular scales probed by Planck, the cosmic microwave background (CMB) anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this eect, detecting lensing independently in the 100, 143, and 217 GHz frequency bands with an overall significa...... information, our measurement corresponds to a 4% constraint on the amplitude of the lensing potential power spectrum, or a 2% constraint on the root-mean-squared amplitude of matter fluctuations at z ∼ 2....

Shallow rainwater lenses in deltaic areas with saline seepage

NARCIS (Netherlands)

Louw, de P.G.B.; Eeman, S.; Siemon, B.; `Voortman, B.R.; Gunnink, J.; Baaren, E.S.; Oude Essink, G.H.P.

2011-01-01

In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and

Shallow rainwater lenses in deltaic areas with saline seepage

NARCIS (Netherlands)

De Louw, Perry G.B.; Eeman, Sara; Siemon, Bernhard; Voortman, Bernard R.; Gunnink, Jan; Van Baaren, Esther S.; Oude Essink, Gualbert

2011-01-01

In deltaic areas with saline seepage, fresh water availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence

Adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis to silicone-hydrogel contact lenses.

Science.gov (United States)

Henriques, Mariana; Sousa, Cláudia; Lira, Madalena; Elisabete, M; Oliveira, Real; Oliveira, Rosário; Azeredo, Joana

2005-06-01

The purpose of this study is to compare the adhesion capabilities of the most important etiologic agents of microbial ocular infection to the recently available silicone-hydrogel lenses with those to a conventional hydrogel lens. In vitro static adhesion assays of Pseudomonas aeruginosa 10,145, Staphylococcus epidermidis 9142 (biofilm-positive), and 12,228 (biofilm-negative) to two extended-wear silicone-hydrogel lenses (balafilcon A and lotrafilcon A), a daily wear silicone-hydrogel lens (galyfilcon A) and a conventional hydrogel (etafilcon A) were performed. To interpret the adhesion results, lens surface relative hydrophobicity was assessed by water contact angle measurements. P. aeruginosa and S. epidermidis 9142 exhibited greater adhesion capabilities to the extended wear silicone-hydrogel lenses than to the daily wear silicone- and conventional hydrogel lenses (p adhesion extent of these strains to galyfilcon A and etafilcon A. The biofilm negative strain of S. epidermidis adhered in larger extents to the silicone-hydrogel lenses than to the conventional hydrogel (p contact angle measurements revealed that the extended wear silicone-hydrogel lenses are hydrophobic, whereas the daily wear silicone- and conventional hydrogel lenses are hydrophilic. As a result of their hydrophobicity, the extended wear silicone-hydrogel lenses (lotrafilcon A and balafilcon A) may carry higher risk of microbial contamination than both the hydrophilic daily wear silicone-hydrogel lens, galyfilcon A and the conventional hydrogel lens, etafilcon A.

Low Cost DIY Lenses kit For High School Teaching

Science.gov (United States)

Thepnurat, Meechai; Saphet, Parinya; Tong-on, Anusorn

2017-09-01

A set of lenses was fabricated from a low cost materials in a DIY (Do it yourself) process. The purpose was to demonstrate to teachers and students in high schools how to construct lenses by themselves with the local available materials. The lenses could be applied in teaching Physics, about the nature of a lens such as focal length and light rays passing through lenses in either direction, employing a set of simple laser pointers. This instrumental kit was made from a transparent 2 mm thick of acrylic Perspex. It was cut into rectangular pieces with dimensions of 2x15 cm2 and bent into curved shape by a hot air blower on a cylindrical wooden rod with curvature radii of about 3-4.5 cm. Then a pair of these Perspex were formed into a hollow thick lenses with a base supporting platform, so that any appropriate liquids could be filled in. The focal length of the lens was measured from laser beam drawing on a paper. The refractive index, n (n) of a filling liquid could be calculated from the measured focal length (f). The kit was low cost and DIY but was greatly applicable for optics teaching in high school laboratory.

Revised Unfilling Procedure for Solid Lithium Lenses

International Nuclear Information System (INIS)

Leveling, A.

2003-01-01

A procedure for unfilling used lithium lenses to has been described in Pbar Note 664. To date, the procedure has been used to disassemble lenses 20, 21, 17, 18, and 16. As a result of this work, some parts of the original procedure were found to be time consuming and ineffective. Modifications to the original procedure have been made to streamline the process and are discussed in this note. The revised procedure is included in this note.

The Mathematical Theory of Multifocal Lenses

Institute of Scientific and Technical Information of China (English)

Jacob RUBINSTEIN

2017-01-01

This paper presents the fundamental optical concepts of designing multifocal ophthalmic lenses and the mathematical methods associated with them.In particular,it is shown that the design methodology is heavily based on differential geometric ideas such as Willmore surfaces.A key role is played by Hamilton's eikonal functions.It is shown that these functions capture all the information on the local blur and distortion created by the lenses.Along the way,formulas for computing the eikonal functions are derived.Finally,the author lists a few intriguing mathematical problems and novel concepts in optics as future projects.

Microbiologic study of soft contact lenses after laser subepithelial keratectomy for myopia.

Science.gov (United States)

Hondur, Ahmet; Bilgihan, Kamil; Cirak, Meltem Yalinay; Dogan, Ozgur; Erdinc, Alper; Hasanreisoglu, Berati

2008-01-01

To evaluate the extent and agents of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and to correlate the findings with clinical data. Disposable soft contact lenses were collected from 52 eyes of 26 consecutive patients treated with LASEK for myopia. The patients were treated with a fixed combination of tobramycin and diclofenac until epithelial closure. The lenses were removed on the fourth or fifth postoperative day with sterile forceps and immediately placed in sterile tubes containing culture media brain-heart infusion broth. The lenses were evaluated for microbial colonization. Of the 52 contact lenses analyzed, six (11.5%) had positive cultures. However, no clinical finding of infection was noted. Isolated microorganisms were coagulase-negative staphylococci (two lenses), Stenotrophomonas maltophilia (two lenses), Acinetobacter species (one lens), and Aeromonas hydrophila (one lens). Except for one case, the microorganisms were sensitive to the administered antibiotic. The risk of infectious keratitis after LASEK seems to be low. Except for staphylococci, the isolated microorganisms have not been previously reported to colonize the ocular surface or cause keratitis after refractive surgery. These findings may suggest a changing trend of potentially infectious agents after surface ablation.

Evaluation of antioxidants and argpyrimidine in normal and cataractous lenses in north Indian population

Directory of Open Access Journals (Sweden)

Bharani K Mynampati

2017-07-01

Full Text Available AIM: To assess the level of glutathione, thioltransferase, and argpyrimidine in nuclear and cortical cataractous lenses as well as in the clear lenses in the north Indian population. METHODS: Human cataractous lenses were collected from the patients who underwent extracapsular cataract extraction surgery; clear lenses were collected from the freshly donated eye bank eyes. Antioxidant molecules such as glutathione and thioltransferase enzyme activity were measured; simultaneously in these lenses a blue fluorophore argpyrimidine, an advanced glycation end (AGE product level was assessed using high performance liquid chromatography (HPLC. RESULTS: The protein concentration was found to be present at higher levels in the control lenses compared to cataract lenses. A significant decrease in the glutathione level was observed in the nuclear cataractous lenses compared to cortical cataractous (P=0.004 and clear lenses (P≤0.005, but no significant change in the level of antioxidant enzyme thioltransferase was observed. Further, argpyrimidine a blue fluorophore (AGE was found to be significantly higher in the nuclear cataract (P=0.013 compared to cortical cataract lenses. CONCLUSION: Antioxidants such as glutathione significantly decrease in age-related nuclear and cortical cataract and an AGE, argpyrimidine are present at significantly higher levels in nuclear cataract.

Constraints on Neutral Hydrogen Outflow from the Warm Rocky Planet GJ1132b using Lyman-alpha Transit Observations

Science.gov (United States)

Waalkes, William; Berta-Thompson, Zachory; Charbonneau, David; Irwin, Jonathan; Newton, Elisabeth; Dittmann, Jason; Bourrier, Vincent; Ehrenreich, David; Kempton, Eliza

2018-01-01

GJ1132b is one of the few known Earth-sized planets, and at 12 pc away it is also one of the closest known transiting planets. With an equilibrium temperature of 500 K, this planet is too hot to be habitable but we can use it to learn about the presence and volatile content of rocky planet atmospheres around M dwarf stars. Using Hubble STIS spectra during primary transit, we explore the potential for UV transit detections of GJ1132b. If we were to observe a deep Lyman-α transit, that would indicate the presence of a neutral hydrogen envelope flowing from GJ1132b. On the other hand, ruling out deep absorption from neutral hydrogen may indicate that this planet has either retained its volatiles or lost them very early in the star’s life. We carry out this analysis by extracting 1D spectra from the STIS pipeline, splitting the time-tagged spectra into higher resolution samples, and producing light curves of the red and blue wings of the Lyman-α line. We fit for the baseline stellar flux and transit depths in order to constrain the characteristics of the cloud of neutral hydrogen gas that may surround the planet. Our work extends beyond the transit study into an analysis of the stellar variability and Lyman-α spectrum of GJ1132, a slowly-rotating 0.18 MSun M dwarf with previously uncharacterized UV activity. Understanding the role that UV variability plays in planetary atmospheres and volatile retention is crucial to assess atmospheric evolution and the habitability of cooler rocky planets.

Biochemical analyses of lipids deposited on silicone hydrogel lenses

Directory of Open Access Journals (Sweden)

Shin Hatou

2010-07-01

Conclusions: The quantity of total lipid and cholesterol deposited on the 3 silicone hydrogel lenses tested did not differ. However, there were significant differences in the amounts of phospholipid deposited among the 3 silicone hydrogel lenses, of which clinical significance should be explored in the future study.

Power profiles of single vision and multifocal soft contact lenses.

Science.gov (United States)

Wagner, Sandra; Conrad, Fabian; Bakaraju, Ravi C; Fedtke, Cathleen; Ehrmann, Klaus; Holden, Brien A

2015-02-01

The purpose of this study was to investigate the optical zone power profile of the most commonly prescribed soft contact lenses to assess their potential impact on peripheral refractive error and hence myopia progression. The optical power profiles of six single vision and ten multifocal contact lenses of five manufacturers in the powers -1.00 D, -3.00 D, and -6.00 D were measured using the SHSOphthalmic (Optocraft GmbH, Erlangen, Germany). Instrument repeatability was also investigated. Instrument repeatability was dependent on the distance from the optical centre, manifesting unreliable data for the central 1mm of the optic zone. Single vision contact lens measurements of -6.00 D lenses revealed omafilcon A having the most negative spherical aberration, lotrafilcon A having the least. Somofilcon A had the highest minus power and lotrafilcon A the biggest deviation in positive direction, relative to their respective labelled powers. Negative spherical aberration occurred for almost all of the multifocal contact lenses, including the centre-distance designs etafilcon A bifocal and omafilcon A multifocal. Lotrafilcon B and balafilcon A seem to rely predominantly on the spherical aberration component to provide multifocality. Power profiles of single vision soft contact lenses varied greatly, many having a negative spherical aberration profile that would exacerbate myopia. Some lens types and powers are affected by large intra-batch variability or power offsets of more than 0.25 dioptres. Evaluation of power profiles of multifocal lenses was derived that provides helpful information for prescribing lenses for presbyopes and progressing myopes. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Simulations for 21 cm radiation lensing at EoR redshifts

Science.gov (United States)

Romeo, Alessandro; Metcalf, Robert Benton; Pourtsidou, Alkistis

2018-02-01

We introduce simulations aimed at assessing how well weak gravitational lensing of 21cm radiation from the Epoch of Reionization (z ˜ 8) can be measured by a Square Kilometre Array (SKA)-like radio telescope. A simulation pipeline has been implemented to study the performance of lensing reconstruction techniques. We show how well the lensing signal can be reconstructed using the 3D quadratic lensing estimator in Fourier space assuming different survey strategies. The numerical code introduced in this work is capable of dealing with issues that cannot be treated analytically such as the discreteness of visibility measurements and the inclusion of a realistic model for the antennas distribution. This paves the way for future numerical studies implementing more realistic re-ionization models, foreground subtraction schemes, and testing the performance of lensing estimators that take into account the non-Gaussian distribution of HI after re-ionization. If multiple frequency channels covering z ˜ 7-11.6 are combined, Phase 1 of SKA-Low should be able to obtain good quality images of the lensing potential with a total resolution of ˜1.6 arcmin. The SKA-Low Phase 2 should be capable of providing images with high fidelity even using data from z ˜ 7.7 to 8.3. We perform tests aimed at evaluating the numerical implementation of the mapping reconstruction. We also discuss the possibility of measuring an accurate lensing power spectrum. Combining data from z ˜ 7 to 11.6 using the SKA2-Low telescope model, we find constraints comparable to sample variance in the range L < 1000, even for survey areas as small as 25 deg2.

Gravitational lensing of the CMB: A Feynman diagram approach

Directory of Open Access Journals (Sweden)

Elizabeth E. Jenkins

2014-09-01

Full Text Available We develop a Feynman diagram approach to calculating correlations of the Cosmic Microwave Background (CMB in the presence of distortions. As one application, we focus on CMB distortions due to gravitational lensing by Large Scale Structure (LSS. We study the Hu–Okamoto quadratic estimator for extracting lensing from the CMB and derive the noise of the estimator up to O(ϕ4 in the lensing potential ϕ. By identifying the diagrams responsible for the previously noted large O(ϕ4 term, we conclude that the lensing expansion does not break down. The convergence can be significantly improved by a reorganization of the ϕ expansion. Our approach makes it simple to obtain expressions for quadratic estimators based on any CMB channel, including many previously unexplored cases. We briefly discuss other applications to cosmology of this diagrammatic approach, such as distortions of the CMB due to patchy reionization, or due to Faraday rotation from primordial axion fields.

New case of gravitational lensing

Energy Technology Data Exchange (ETDEWEB)

Surdej, J.; Swings, J.-P.; Magain, P.; Borgeest, U.; Kayser, R.; Refsdal, S.; Courvoisier, T.J.-L.; Kellermann, K.I.; Kuehr, H.

1987-10-22

The authors report a brief description of a gravitational lens system UM673 = Q0142 - 100 = PHL3703. It consists of two images, A and B, separated by 2.2 arc s at a redshift zsub(q) = 2.719. The lensing galaxy has also been found. It lies very near the line connecting the two QSO (quasi-stellar objects) images, approx. 0.8 arc s from the fainter one. Application of gravitational optometry to this system leads to a value Msub(o) or approx. = 2.4 x 10/sup 11/ M solar masses for the mass of the lensing galaxy and to ..delta..t approx. 7 weeks for the most likely travel-time difference between the two light paths to the QSO.

Image formation in weak gravitational lensing by tidal charged black holes

International Nuclear Information System (INIS)

Horvath, Zsolt; Gergely, Laszlo Arpad; Hobill, David

2010-01-01

We derive a generic weak lensing equation and apply it for the study of images produced by tidal charged brane black holes. We discuss the similarities and point out the differences with respect to the Schwarzschild black hole weak lensing, to both first- and second-order accuracy, when either the mass or the tidal charge dominates. In the case of mass-dominated weak lensing, we analyze the position of the images, the magnification factors and the flux ratio, as compared to the Schwarzschild lensing. The most striking modification appears in the flux ratio. When the tidal charge represents the dominating lensing effect, the number and orientation of the images with respect to the optical axis resembles the lensing properties of a Schwarzschild geometry, where the sign associated with the mass is opposite to that for the tidal charge. Finally it is found that the ratio of the brightness of the images as a function of image separation in the case of tidal charged black holes obeys a power-law relation significantly different from that of Schwarzschild black holes. This might provide a means for determining the underlying spacetime structure.

Parabolic refractive X-ray lenses: a breakthrough in X-ray optics

CERN Document Server

Lengeler, B; Benner, B; Guenzler, T F; Kuhlmann, M; Tümmler, J; Simionovici, A S; Drakopoulos, M; Snigirev, A; Snigireva, I

2001-01-01

Refractive X-ray lenses, considered for a long time as unfeasible, have been realized with a rotational parabolic profile at our institute: The main features of the new lenses are: they focus in two directions and are free of spherical aberration. By varying the number of individual lenses in the stack the focal length can be chosen in a typical range from 0.5 to 2 m for photon energies between about 6 and 60 keV. The aperture of the lens is about 1 mm matching the angular divergence of undulator beams at 3d generation synchrotron radiation sources. They cope without problems with the heat load from the white beam of an undulator. Finally, they are easy to align and to operate. Refractive X-ray lenses can be used with hard X-rays in the same way as glass lenses can be used for visible light, if it is take into account that the numerical aperture is small (of the order 10 sup - sup 4). Being high-quality optical elements, the refractive X-ray lenses can be used for generating a focal spot in the mu m range wit...

Multiply imaged Transient Events in Cluster Lenses

Science.gov (United States)

Narasimha, Delampady

2018-04-01

ARIES had a successful gravitational microlens project during 1998-2002. A similar monitor for Transient Events in galaxies at high redshift lensed by rich galaxy-clusters provides a challenging possibility with important cosmological implications. Rich galaxy-clusters at intermediate redshifts are powerful gravitational lenses which produce multiple images, in the shape of giant arcs of 5-20" extent, of distant background galaxies in their field. Weak lens shear of the background galaxy distribution can reliably trace the lens mass profile. Multiple images of supernovae or GRBs in the background galaxies can be recorded in a systematic monitor of the system. An unlensed high redshift supernova might not be observable, but when lensed by a galaxy-cluster, it will stand out because the point event brightens relative to the host. The color profile of a high redshift lensed point event will be much more reliable than an unlensed one due to much less host contamination. An estimate of the time delay enables observation of the full light curve of the subsequent images of the event. ARIES can have outside collaboration for multiband simultaneous lightcurves of other images. The measured time delay and position of images of the transient event provide better cosmological constraints including distance scale of the Universe. The Devasthal telescope can detect one or more events by monitoring half a dozen cluster fields over three years time.

Galaxy bias from galaxy-galaxy lensing in the DES Science Verification Data

Energy Technology Data Exchange (ETDEWEB)

Prat, J.; et al.

2016-09-26

We present a measurement of galaxy-galaxy lensing around a magnitude-limited ($i_{AB} < 22.5$) sample of galaxies selected from the Dark Energy Survey Science Verification (DES-SV) data. We split these lenses into three photometric-redshift bins from 0.2 to 0.8, and determine the product of the galaxy bias $b$ and cross-correlation coefficient between the galaxy and dark matter overdensity fields $r$ in each bin, using scales above 4 Mpc/$h$ comoving, where we find the linear bias model to be valid given our current uncertainties. We compare our galaxy bias results from galaxy-galaxy lensing with those obtained from galaxy clustering (Crocce et al. 2016) and CMB lensing (Giannantonio et al. 2016) for the same sample of galaxies, and find our measurements to be in good agreement with those in Crocce et al. (2016), while, in the lowest redshift bin ($z\\sim0.3$), they show some tension with the findings in Giannantonio et al. (2016). Our results are found to be rather insensitive to a large range of systematic effects. We measure $b\\cdot r$ to be $0.87\\pm 0.11$, $1.12 \\pm 0.16$ and $1.24\\pm 0.23$, respectively for the three redshift bins of width $\\Delta z = 0.2$ in the range $0.2strong evidence for a cross-correlation parameter significantly below one in this galaxy sample, except possibly at the lowest redshift bin ($z\\sim 0.3$), where we find $r = 0.71 \\pm 0.11$ when using TPZ, and $0.83 \\pm 0.12$ with BPZ, assuming the difference between the results from the two probes can be solely attributed to the cross-correlation parameter.

AUTOMATED DETECTION OF GALAXY-SCALE GRAVITATIONAL LENSES IN HIGH-RESOLUTION IMAGING DATA

International Nuclear Information System (INIS)

Marshall, Philip J.; Bradac, Marusa; Hogg, David W.; Moustakas, Leonidas A.; Fassnacht, Christopher D.; Schrabback, Tim; Blandford, Roger D.

2009-01-01

We expect direct lens modeling to be the key to successful and meaningful automated strong galaxy-scale gravitational lens detection. We have implemented a lens-modeling 'robot' that treats every bright red galaxy (BRG) in a large imaging survey as a potential gravitational lens system. Having optimized a simple model for 'typical' galaxy-scale gravitational lenses, we generate four assessments of model quality that are then used in an automated classification. The robot infers from these four data the lens classification parameter H that a human would have assigned; the inference is performed using a probability distribution generated from a human-classified training set of candidates, including realistic simulated lenses and known false positives drawn from the Hubble Space Telescope (HST) Extended Groth Strip (EGS) survey. We compute the expected purity, completeness, and rejection rate, and find that these statistics can be optimized for a particular application by changing the prior probability distribution for H; this is equivalent to defining the robot's 'character'. Adopting a realistic prior based on expectations for the abundance of lenses, we find that a lens sample may be generated that is ∼100% pure, but only ∼20% complete. This shortfall is due primarily to the oversimplicity of the model of both the lens light and mass. With a more optimistic robot, ∼90% completeness can be achieved while rejecting ∼90% of the candidate objects. The remaining candidates must be classified by human inspectors. Displaying the images used and produced by the robot on a custom 'one-click' web interface, we are able to inspect and classify lens candidates at a rate of a few seconds per system, suggesting that a future 1000 deg. 2 imaging survey containing 10 7 BRGs, and some 10 4 lenses, could be successfully, and reproducibly, searched in a modest amount of time. We have verified our projected survey statistics, albeit at low significance, using the HST EGS data

Effect of undetected gravitational lenses on statistical measures of quasar evolution

International Nuclear Information System (INIS)

Turner, E.L.

1980-01-01

Brightness amplifications by undetected gravitational lenses could be responsible in part for the apparent evolution of quasars, particularly for those which appear to be of high luminosity. It is shown that values of Vover-bar/over-barVover-bar/sub M/> or =0.6 and number-magnitude slopes > or =0.9 need not necessarily imply source density evolution if lensing events are common. Quasar samples which are defined by flux limits and minimum luminosities will preferentially include gravitational lens systems. Even if lensing events are quite rare, a large fraction of the lensed quasars will appear more luminous than the most luminous unlensed quasar

Probabilities for gravitational lensing by point masses in a locally inhomogeneous universe

International Nuclear Information System (INIS)

Isaacson, J.A.; Canizares, C.R.

1989-01-01

Probability functions for gravitational lensing by point masses that incorporate Poisson statistics and flux conservation are formulated in the Dyer-Roeder construction. Optical depths to lensing for distant sources are calculated using both the method of Press and Gunn (1973) which counts lenses in an otherwise empty cone, and the method of Ehlers and Schneider (1986) which projects lensing cross sections onto the source sphere. These are then used as parameters of the probability density for lensing in the case of a critical (q0 = 1/2) Friedmann universe. A comparison of the probability functions indicates that the effects of angle-averaging can be well approximated by adjusting the average magnification along a random line of sight so as to conserve flux. 17 references

Power Profiles of Commercial Multifocal Soft Contact Lenses.

Science.gov (United States)

Kim, Eon; Bakaraju, Ravi C; Ehrmann, Klaus

2017-02-01

To evaluate the optical power profiles of commercially available soft multifocal contact lenses and compare their optical designs. The power profiles of 38 types of multifocal contact lenses-three lenses each-were measured in powers +6D, +3D, +1D, -1D, -3D, and -6D using NIMO TR1504 (Lambda-X, Belgium). All lenses were measured in phosphate buffered saline across 8 mm optic zone diameter. Refractive index of each lens material was measured using CLR 12-70 (Index Instruments, UK), which was used for converting measured power in the medium to in-air radial power profiles. Three basic types of power profiles were identified: center-near, center-distance, and concentric-zone ring-type designs. For most of the lens types, the relative plus with respect to prescription power was lower than the corresponding spectacle add. For some lens types, the measured power profiles were shifted by up to 1D across the power range relative to their labeled power. Most of the lenses were designed with noticeable amounts of spherical aberration. The sign and magnitude of spherical aberration can either be power dependent or consistent across the power range. Power profiles can vary widely between the different lens types; however, certain similarities were also observed between some of the center-near designs. For the more recently released lens types, there seems to be a trend emerging to reduce the relative plus with respect to prescription power, include negative spherical aberration, and keep the power profiles consistent across the power range.

Creating School Change: Discovering a Choice of Lenses for the School Administrator.

Science.gov (United States)

Amatea, Ellen S.; And Others

1996-01-01

Proposes a variety of epistemological lenses for viewing the school change process for school administrators' use. Applies these lenses in an actual case study depicting school change, illustrating how administrators can shift focus, position, and mode of inquiry from their usual rational viewpoint. Analyzes implications of using such lenses for…

Electron lenses for the large hadron collider

CERN Document Server

Stancari†, G; Bruce, R; Redaelli, S; Rossi, A; Salvachua Ferrando, B

2014-01-01

Electron lenses are pulsed, magnetically confined electron beamswhose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-bybunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beamcompensation, and for the demonstration of halo scrapingwith hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. A conceptual design was recently completed, and the project is moving towards a technical design in 2014–2015 for construction in 2015–2017, if needed, after resuming LHC operations and re-assessing collimation needs and requirements at 6.5 TeV. Because of the...

Realization of first order optical systems using thin lenses

International Nuclear Information System (INIS)

Sudarshan, E.C.G.; Mukunda, N.; Simon, R.

1983-09-01

A first order optical system is investigated in full generality within the context of wave optics. We reduce the problem to a study of the ray transfer matrices. The simplest such systems correspond to axially symmetric propagation. Realization of such systems by centrally located lenses separated by finite distances is studied. It is shown that every axially symmetric first order system can be realized using at most three lenses. Among anisotropic systems it is proven that every symplectic ray transfer matrix, and no others, can be realized using lenses and free propagations. Suggestions for further study of the general first order system are outlined. 16 references

Glutathione preservation during storage of rat lenses in optisol-GS and castor oil.

Science.gov (United States)

Holm, Thomas; Brøgger-Jensen, Martin Rocho; Johnson, Leif; Kessel, Line

2013-01-01

Glutathione concentration in the lens decreases in aging and cataractous lenses, providing a marker for tissue condition. Experimental procedures requiring unfrozen lenses from donor banks rely on transportation in storage medium, affecting lens homeostasis and alterations in glutathione levels. The aim of the study was to examine the effects of Optisol-GS and castor oil on lens condition, determined from their ability to maintain glutathione concentrations. Rat lenses were stored in the two types of storage media at varying time intervals up to 3 days. Glutathione concentration was afterwards determined in an enzymatic detection assay, specific for both reduced and oxidized forms. Lenses removed immediately after death exhibited a glutathione concentration of 4.70±0.29 mM. In vitro stored lenses in Optisol-GS lost glutathione quickly, ending with a concentration of 0.60±0.34 mM after 3 days while castor oil stored lenses exhibited a slower decline and ended at 3 times the concentration. A group of lenses were additionally stored under post mortem conditions within the host for 6 hours before its removal. Total glutathione after 6 hours was similar to that of lenses removed immediately after death, but with altered GSH and GSSG concentrations. Subsequent storage of these lenses in media showed changes similar to those in the first series of experiments, albeit to a lesser degree. It was determined that storage in Optisol-GS resulted in a higher loss of glutathione than lenses stored in castor oil. Storage for more than 12 hours reduced glutathione to half its original concentration, and was considered unusable after 24 hours.

Glutathione preservation during storage of rat lenses in optisol-GS and castor oil.

Directory of Open Access Journals (Sweden)

Thomas Holm

Full Text Available BACKGROUND: Glutathione concentration in the lens decreases in aging and cataractous lenses, providing a marker for tissue condition. Experimental procedures requiring unfrozen lenses from donor banks rely on transportation in storage medium, affecting lens homeostasis and alterations in glutathione levels. The aim of the study was to examine the effects of Optisol-GS and castor oil on lens condition, determined from their ability to maintain glutathione concentrations. METHODOLOGY/PRINCIPAL FINDINGS: Rat lenses were stored in the two types of storage media at varying time intervals up to 3 days. Glutathione concentration was afterwards determined in an enzymatic detection assay, specific for both reduced and oxidized forms. Lenses removed immediately after death exhibited a glutathione concentration of 4.70±0.29 mM. In vitro stored lenses in Optisol-GS lost glutathione quickly, ending with a concentration of 0.60±0.34 mM after 3 days while castor oil stored lenses exhibited a slower decline and ended at 3 times the concentration. A group of lenses were additionally stored under post mortem conditions within the host for 6 hours before its removal. Total glutathione after 6 hours was similar to that of lenses removed immediately after death, but with altered GSH and GSSG concentrations. Subsequent storage of these lenses in media showed changes similar to those in the first series of experiments, albeit to a lesser degree. CONCLUSIONS/SIGNIFICANCE: It was determined that storage in Optisol-GS resulted in a higher loss of glutathione than lenses stored in castor oil. Storage for more than 12 hours reduced glutathione to half its original concentration, and was considered unusable after 24 hours.

On Using a Space Telescope to Detect Weak-lensing Shear

Science.gov (United States)

Tung, Nathan; Wright, Edward

2017-11-01

Ignoring redshift dependence, the statistical performance of a weak-lensing survey is set by two numbers: the effective shape noise of the sources, which includes the intrinsic ellipticity dispersion and the measurement noise, and the density of sources that are useful for weak-lensing measurements. In this paper, we provide some general guidance for weak-lensing shear measurements from a “generic” space telescope by looking for the optimum wavelength bands to maximize the galaxy flux signal-to-noise ratio (S/N) and minimize ellipticity measurement error. We also calculate an effective galaxy number per square degree across different wavelength bands, taking into account the density of sources that are useful for weak-lensing measurements and the effective shape noise of sources. Galaxy data collected from the ultra-deep UltraVISTA Ks-selected and R-selected photometric catalogs (Muzzin et al. 2013) are fitted to radially symmetric Sérsic galaxy light profiles. The Sérsic galaxy profiles are then stretched to impose an artificial weak-lensing shear, and then convolved with a pure Airy Disk PSF to simulate imaging of weak gravitationally lensed galaxies from a hypothetical diffraction-limited space telescope. For our model calculations and sets of galaxies, our results show that the peak in the average galaxy flux S/N, the minimum average ellipticity measurement error, and the highest effective galaxy number counts all lie around the K-band near 2.2 μm.

Source Plane Reconstruction of the Bright Lensed Galaxy RCSGA 032727-132609

Science.gov (United States)

Sharon, Keren; Gladders, Michael D.; Rigby, Jane R.; Wuyts, Eva; Koester, Benjamin P.; Bayliss, Matthew B.; Barrientos, L. Felipe

2011-01-01

We present new HST/WFC3 imaging data of RCS2 032727-132609, a bright lensed galaxy at z=1.7 that is magnified and stretched by the lensing cluster RCS2 032727-132623. Using this new high-resolution imaging, we modify our previous lens model (which was based on ground-based data) to fully understand the lensing geometry, and use it to reconstruct the lensed galaxy in the source plane. This giant arc represents a unique opportunity to peer into 100-pc scale structures in a high redshift galaxy. This new source reconstruction will be crucial for a future analysis of the spatially-resolved rest-UV and rest-optical spectra of the brightest parts of the arc.

Dense arrays of millimeter-sized glass lenses fabricated at wafer-level.

Science.gov (United States)

Albero, Jorge; Perrin, Stéphane; Bargiel, Sylwester; Passilly, Nicolas; Baranski, Maciej; Gauthier-Manuel, Ludovic; Bernard, Florent; Lullin, Justine; Froehly, Luc; Krauter, Johann; Osten, Wolfgang; Gorecki, Christophe

2015-05-04

This paper presents the study of a fabrication technique of lenses arrays based on the reflow of glass inside cylindrical silicon cavities. Lenses whose sizes are out of the microfabrication standards are considered. In particular, the case of high fill factor arrays is discussed in detail since the proximity between lenses generates undesired effects. These effects, not experienced when lenses are sufficiently separated so that they can be considered as single items, are corrected by properly designing the silicon cavities. Complete topographic as well as optical characterizations are reported. The compatibility of materials with Micro-Opto-Electromechanical Systems (MOEMS) integration processes makes this technology attractive for the miniaturization of inspection systems, especially those devoted to imaging.

Chromatic aberrations of electrostatic axisymmetric lenses produced by circular cylinders

International Nuclear Information System (INIS)

Baranova, L.A.; Ul'yanova, N.S.; Yavor, S.Ya.

1989-01-01

Ion beams both to test material and for technological processes have being used lately in science and technology more and more. Electrostatic lenses are used, as a rule, for such beam production. Coefficients of chromatic aberrration for a wide range of changes in lense parameters are calculated on the basis of analytical expressions to determine the potential in immerse and isolated lenses. The chromatic aberration coefficient is presented as a polynomial according to the degrees of reverse increase, that permits to calculate a circle of blurring of subject arbitrary position

What is Gravitational Lensing? (LBNL Summer Lecture Series)

Energy Technology Data Exchange (ETDEWEB)

Leauthaud, Alexie [Univ. of California, Berkeley, CA (United States). Berkeley Center for Cosmological Physics (BCCP); Nakajima, Reiko [Univ. of California, Berkeley, CA (United States). Berkeley Center for Cosmological Physics (BCCP)

2009-07-28

Summer Lecture Series 2009: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

In vitro power profiles of daily disposable contact lenses.

Science.gov (United States)

Belda-Salmerón, Lurdes; Madrid-Costa, David; Ferrer-Blasco, Teresa; García-Lázaro, Santiago; Montés-Micó, Robert

2013-10-01

To evaluate and compare the distribution of refractive power within the optic zone of different soft contact lenses and to investigate the effect of lens decentration on the power profiles. The Nimo TR1504 instrument was used to measure the optical power across different aperture diameters (from 1.5mm to 5.5mm in steps of 0.5mm) of four daily disposable contact lenses: DAILIES TOTAL1, Proclear 1-Day, SofLens daily disposable and 1-DAY ACUVUE MOIST. Measurements were performed using a wet cell. Power data were evaluated when contact lenses were in its centered position and after inducing different amounts of lens decentration (from 0.2mm to 1.0mm in steps of 0.2mm). All contact lenses showed an increase - more negative - in lens power with distance from the lens center. The amount of change varied depending on the lens. It was about 10% of lens power for DAILIES TOTAL1 (-0.29diopters (D)), SofLens daily disposable (-0.36D), and Proclear 1-Day (-0.32D) whereas 1-DAY ACUVUE MOIST showed a percentage variation of 3.3% (-0.10D). After inducing a lens decentration up to 1mm, the power curves were shifted in the negative direction. However, the change obtained in lens power compared with well-centered position was always lower than a quarter of diopter both for all the lenses and aperture diameters. Our results showed a variation of the refractive power from the lens center, becoming more negative toward the periphery, with a negligible effect of the decentration for all disposable contact lenses studied. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

Direct Laser Writing of Nanophotonic Structures on Contact Lenses.

Science.gov (United States)

AlQattan, Bader; Yetisen, Ali K; Butt, Haider

2018-04-24

Contact lenses are ubiquitous biomedical devices used for vision correction and cosmetic purposes. Their application as quantitative analytical devices is highly promising for point-of-care diagnostics. However, it is a challenge to integrate nanoscale features into commercial contact lenses for application in low-cost biosensors. A neodymium-doped yttrium aluminum garnet (Nd:YAG) laser (1064 nm, 3 ns pulse, 240 mJ) in holographic interference patterning mode was utilized to produce optical nanostructures over the surface of a hydrogel contact lens. One-dimensional (925 nm) and two-dimensional (925 nm × 925 nm) nanostructures were produced on contact lenses and analyzed by spectroscopy and angle-resolve measurements. The holographic properties of these nanostructures were tested in ambient moisture, fully hydrated, and artificial tear conditions. The measurements showed a rapid tuning of optical diffraction from these nanostructures from 41 to 48°. The nanostructures were patterned near the edges of the contact lens to avoid any interference and obstruction to the human vision. The formation of 2D nanostructures on lenses increased the diffraction efficiency by more than 10%. The versatility of the holographic laser ablation method was demonstrated by producing four different 2D nanopattern geometries on contact lenses. Hydrophobicity of the contact lens was characterized by contact angle measurements, which increased from 59.0° at pristine condition to 62.5° at post-nanofabrication. The holographic nanostructures on the contact lens were used to sense the concentration of Na + ions. Artificial tear solution was used to simulate the conditions in dry eye syndrome, and nanostructures on the contact lenses were used to detect the electrolyte concentration changes (±47 mmol L -1 ). Nanopatterns on a contact lens may be used to sense other ocular diseases in early stages at point-of-care settings.

Broad spectrum antimicrobial activity of melimine covalently bound to contact lenses.

Science.gov (United States)

Dutta, Debarun; Cole, Nerida; Kumar, Naresh; Willcox, Mark D P

2013-01-07

To develop a stable antimicrobial contact lens, which is effective against the International Organization for Standardization (ISO) panel microorganisms, Acanthamoeba castellanii and drug resistant strains of Pseudomonas aeruginosa and Staphylococcus aureus. Melimine was covalently incorporated into etafilcon A lenses. The amount of peptide present on the lens surface was quantified using amino acid analysis. After coating, the heat stability (121°C), lens surface hydrophobicity (by captive bubble), and in vitro cytotoxicity to mouse L929 cells of the lenses were investigated. Antimicrobial activity against the micro-organisms was evaluated by viable plate count and fluorescence microscopy, measuring the proportion of cell death compared with control lenses with no melimine. The most effective concentration was determined to be 152 ± 44 μg lens(-1) melimine on the lens surface. After coating, lenses were relatively hydrophilic and were nontoxic to mammalian cells. The activity remained high after autoclaving (e.g., 3.1, 3.9, 1.2, and 1.0 log inhibition against P. aeruginosa, S. aureus, A. castellanii, and Fusarium solani, respectively). Fluorescence microscopy confirmed significantly reduced (P bacteria to melimine contact lenses. Viable count confirmed that lenses were active against all the bacteria and fungi from the ISO panel, Acanthamoeba and gave at least 2 log inhibition against all the multidrug resistant S. aureus and P. aeruginosa strains. Melimine may offer excellent potential for development as a broad spectrum antimicrobial coating for contact lenses, showing activity against all the bacterial and fungal ISO panel microorganisms, Acanthamoeba, and antibiotic resistant strains of P. aeruginosa and S. aureus.

Fermat Potentials of Embedded Lensing, the Integrated Sachs-Wolfe Effect, and Weak-Lensing of CMB by Cosmic Voids

Science.gov (United States)

Chen, Bin; Kantowski, R.; Dai, X.

2014-01-01

We have developed an accurate gravitational lens theory for an inhomogeneity embedded in an otherwise homogeneous universe, which to the lowest order is applicable to any mass distribution. We derive the Fermat potential for a spherically symmetric lens embedded in a FLRW cosmology and use it to investigate the late-time integrated Sachs-Wolfe effect (ISW) caused by individual large scale inhomogeneities, in particular, cosmic voids. We present a simple analytical expression for the CMB temperature fluctuation across such a lens as the derivative of the lens Fermat potential. Our formalism is applicable to both linear and nonlinear density evolution scenarios, to arbitrarily large density contrasts, and to all open and closed background cosmologies. Our results are particularly useful for modeling ISW effects extracted through stacking large numbers of cosmic voids and clusters (that is, the aperture photometry method). For structures co-expanding with the background cosmology, i.e., for time-independent density contrasts, we find that the gravitational lensing time delay alone can produce fluctuations of the order of seen in recent observations by WMAP and Planck. We revisit the possibility of explaining the non-Gaussian cold spot on the south hemisphere via the Rees-Sciama effect of a large cosmic void using constraints obtained from the most recent void catalogs and our new void-lensing formalism, and compare it with other explanations such as a collapsing cosmic texture. We also study the remapping of primordial CMB anisotropies, the weak-lensing shear, and magnification caused by void lensing.

Evidence of lensing of the cosmic microwave background by dark matter halos.

Science.gov (United States)

Madhavacheril, Mathew; Sehgal, Neelima; Allison, Rupert; Battaglia, Nick; Bond, J Richard; Calabrese, Erminia; Caligiuri, Jerod; Coughlin, Kevin; Crichton, Devin; Datta, Rahul; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Fogarty, Kevin; Grace, Emily; Hajian, Amir; Hasselfield, Matthew; Hill, J Colin; Hilton, Matt; Hincks, Adam D; Hlozek, Renée; Hughes, John P; Kosowsky, Arthur; Louis, Thibaut; Lungu, Marius; McMahon, Jeff; Moodley, Kavilan; Munson, Charles; Naess, Sigurd; Nati, Federico; Newburgh, Laura; Niemack, Michael D; Page, Lyman A; Partridge, Bruce; Schmitt, Benjamin; Sherwin, Blake D; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Thornton, Robert; Van Engelen, Alexander; Ward, Jonathan T; Wollack, Edward J

2015-04-17

We present evidence of the gravitational lensing of the cosmic microwave background by 10(13) solar mass dark matter halos. Lensing convergence maps from the Atacama Cosmology Telescope Polarimeter (ACTPol) are stacked at the positions of around 12 000 optically selected CMASS galaxies from the SDSS-III/BOSS survey. The mean lensing signal is consistent with simulated dark matter halo profiles and is favored over a null signal at 3.2σ significance. This result demonstrates the potential of microwave background lensing to probe the dark matter distribution in galaxy group and galaxy cluster halos.

The effects of two different types of bandage contact lenses on the healthy canine eye.

Science.gov (United States)

Braus, Barbara Katharina; Riedler, Daniela; Tichy, Alexander; Spergser, Joachim; Schwendenwein, Ilse

2018-02-06

To compare two types of bandage contact lenses on the healthy canine eye. Six healthy Beagles. Two different types of bandage contact lenses (single sized human silicone contact lens 'PureVision 2' (Bausch & Lomb Incorporated, Rochester, NY, USA) and specially designed veterinary hydrogel contact lens 'AcriVet Pat D' (Bausch & Lomb Incorporated) were placed in 12 eyes of healthy Beagle dogs. Retention times and the effects of the lenses regarding irritation of the eye, changes in tear production, impact of contact lenses on tonometric readings, and cytologic and microbiological alterations of the canine eye were investigated. Mean retention times for veterinary hydrogel lenses with special dimensions were significantly shorter (2 days) than for one size human silicon lenses (8.8 days). Irritation scores were overall low for both types of lenses apart from one human lens causing severe irritation and keratoconjunctivitis as a sequel to folding and displacement. Tear production remained stable in human contact lenses. Intraocular pressure readings with a contact lens in place were only slightly altered; the most accurate readings were obtained through a human lens with an applanation tonometer. Cytology revealed a slight, nonsignificant increase in neutrophilic granulocytes with both types of lenses; the microflora did not change significantly. Human silicone lenses have significantly longer retention times and are less expensive than veterinary hydrogel lenses. In regard to irritation, bacterial growth and inflammation, both types of lenses can be recommended for use in canine eyes. © 2018 American College of Veterinary Ophthalmologists.

Observations of Cluster Substructure using Weakly Lensed Sextupole Moments

Energy Technology Data Exchange (ETDEWEB)

Irwin, John

2003-08-01

Since dark matter clusters and groups may have substructure, we have examined the sextupole content of Hubble images looking for a curvature signature in background galaxies that would arise from galaxy-galaxy lensing. We describe techniques for extracting and analyzing sextupole and higher weakly lensed moments. Indications of substructure, via spatial clumping of curved background galaxies, were observed in the image of CL0024 and then surprisingly in both Hubble deep fields. We estimate the dark cluster masses in the deep field. Alternatives to a lensing hypothesis appear improbable, but better statistics will be required to exclude them conclusively. Observation of sextupole moments would then provide a means to measure dark matter structure on smaller length scales than heretofore.

Twenty years of research on fungal-plant interactions on Lyman Glacier forefront—lessons learned and questions yet unanswered

Science.gov (United States)

Ari Jumpponen; Shawn P. Brown; James M. Trappe; Efrén Cázares; Rauni. Strömmer

2012-01-01

Retreating glaciers and the periglacial areas that they vacate produce a harsh environment of extreme radiation, nutrient limitations and temperature oscillations. They provide a model system for studying mechanisms that drive the establishment and early assembly of communities. Here, we synthesize more than 20 years of research at the Lyman Glacier forefront in the...

Extended release of hyaluronic acid from hydrogel contact lenses for dry eye syndrome.

Science.gov (United States)

Maulvi, Furqan A; Soni, Tejal G; Shah, Dinesh O

2015-01-01

Current dry eye treatment includes delivering comfort enhancing agents to the eye via eye drops, but low residence time of eye drops leads to low bioavailability. Frequent administration leads to incompliance in patients, so there is a great need for medical device such as contact lenses to treat dry eye. Studies in the past have demonstrated the efficacy of hyaluronic acid (HA) in the treatment of dry eyes using eye drops. In this paper, we present two methods to load HA in hydrogel contact lenses, soaking method and direct entrapment. The contact lenses were characterized by studying their optical and physical properties to determine their suitability as extended wear contact lenses. HA-laden hydrogel contact lenses prepared by soaking method showed release up to 48 h with acceptable physical and optical properties. Hydrogel contact lenses prepared by direct entrapment method showed significant sustained release in comparison to soaking method. HA entrapped in hydrogels resulted in reduction in % transmittance, sodium ion permeability and surface contact angle, while increase in % swelling. The impact on each of these properties was proportional to HA loading. The batch with 200-μg HA loading showed all acceptable values (parameters) for contact lens use. Results of cytotoxicity study indicated the safety of hydrogel contact lenses. In vivo pharmacokinetics studies in rabbit tear fluid showed dramatic increase in HA mean residence time and area under the curve with lenses in comparison to eye drop treatment. The study demonstrates the promising potential of delivering HA through contact lenses for the treatment of dry eye syndrome.

Ultraviolet radiation for the sterilization of contact lenses

International Nuclear Information System (INIS)

Gritz, D.C.; Lee, T.Y.; McDonnell, P.J.; Shih, K.; Baron, N.

1990-01-01

Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study

The Effect of Various Contact Lenses on Intraocular Pressure Measurement by Goldman Tonometer

Directory of Open Access Journals (Sweden)

Monireh Mahjoob

2014-06-01

Full Text Available Background: Today, contact lenses have extensive usages. Contact lens places on cornea, so it may induce variation on cornea and these variations can influence the measurement of intraocular pressure (IOP by Goldman tonometer. The aim of this research was to study the effect of various contact lenses on measurement of intraocular pressure by Goldman tonometer. Materials and Methods: In this study, 80 subjects aged 18-25 were selected randomly among patients of Al-Zahra ophthalmology center. None of them has any eye pathological problems. Before wearing the lens, intraocular pressure was measured, and then patients were divided into two groups of soft and hard contact lenses. Soft and hard contact lenses were placed on the eye for two hours, and the intraocular pressure was measured again. Results: The mean of IOP before wearing contact lenses and two hours later was 15.96 mmHg and 13.93, s respectively. Paired test showed a significant difference between IOP before and after wearing contact lenses (p=0.001.There was no significant differences in mean of intraocular pressure decline before and after placing the contact lens in both soft and hard lenses. Conclusion: According to this study, the intraocular pressure decreases after wearing contact lenses (CL. This decline may be due to variation in properties of cornea after wearing CL that can also affect IOP measurement.

Cosmetic Cleansing Oil Absorption by Soft Contact Lenses in Dry and Wet Conditions.

Science.gov (United States)

Tsukiyama, Junko; Miyamoto, Yuko; Kodama, Aya; Fukuda, Masahiko; Shimomura, Yoshikazu

2017-09-01

Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.

30 CFR 18.66 - Tests of windows and lenses.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Tests of windows and lenses. 18.66 Section 18... Tests § 18.66 Tests of windows and lenses. (a) Impact tests. A 4-pound cylindrical weight with a 1-inch-diameter hemispherical striking surface shall be dropped (free fall) to strike the window or lens in its...

Defect inspection of actuator lenses using swept-source optical coherence tomography

Science.gov (United States)

Lee, Jaeyul; Shirazi, Muhammad Faizan; Park, Kibeom; Jeon, Mansik; Kim, Jeehyun

2017-12-01

Actuator lens industries have gained an enormous interest with the enhancement of various latest communication devices, such as mobile phone and notebooks. The quality of the aforementioned devices can be degraded due to the internal defects of actuator lenses. Therefore, in this study, we implemented swept-source optical coherence tomography (SS-OCT) system to inspect defects of actuator lenses. Owing to the high-resolution of the SS-OCT system, defected foreign substances between the actuator lenses, defective regions of lenses and surface stains were more clearly distinguished through three-dimensional (3D) and two-dimensional (2D) cross-sectional OCT images. Therefore, the implemented SS-OCT system can be considered as a potential application to defect inspection of actuator lens.

Microfabricated rubber microscope using soft solid immersion lenses

OpenAIRE

Gambin, Yann; Legrand, Olivier; Quake, Stephen R.

2006-01-01

We show here a technique of soft lithography to microfabricate efficient solid immersion lenses (SIL) out of rubber elastomers. The light collection efficiency of a lens system is described by its numerical aperture (NA), and is critical for applications as epifluorescence microscopy [B. Herman, Fluorescence Microscopy (BIOS Scientific, Oxford/Springer, United Kingdom, 1998). While most simple lens systems have numerical apertures less than 1, the lenses described here have NA=1.25. Better pe...

Slit lamps and lenses: a potential source of nosocomial infections?

Science.gov (United States)

Sobolewska, Bianka; Buhl, Michael; Liese, Jan; Ziemssen, Focke

2018-01-30

The aim of the study was to evaluate the bacterial contamination level of contact surfaces on slit lamps and the grip areas of lenses. Within unannounced audits, two regions of the slit lamps (headrest and joystick), indirect ophthalmoscopy devices, and ultrasound probes were obtained with rayon-tipped swab. Non-contact lenses used for indirect fundoscopy were pressed on RODAC (Replicate Organism Detection and Counting) plates. One hundred and eighty-one surfaces were sampled. The total number of colony-forming units was assessed and bacterial species were identified. Spa-typing and antimicrobial susceptibility testing were performed from Staphylococcus aureus isolates. Among the total bacterial isolates from ophthalmological equipment (lenses: 51 of 78, slit lamps: 43 of 88, ophthalmoscopy helmets: 3 of 8, ultrasound probes: 2 of 7), coagulase-negative staphylococci (CNS) was most frequently found, followed by Micrococcus spp. (lenses vs. slit lamps: P lenses (76%) was significantly higher than that of slit lamps (54%) (P lenses from residents vs. from consultants (78% vs. 35%, P = 0.01). A total of seven different spa-types of S. aureus were isolated. No correlation was found between S. aureus contamination of different ophthalmological equipments (Spearman's rank correlation coefficient, ρ = 0.04, P = 0.75). Methicillin-resistant S. aureus was not detected. Bacterial species of the normal skin flora were isolated from the ophthalmological equipment. The bacterial contamination of the portable devices was significantly higher than that of slit lamps. Therefore, proper hygiene of the mobile instruments should be monitored in order to prevent transmission of bacteria in residents and consultants.

The effect of UV-blocking contact lenses as a therapy for canine chronic superficial keratitis.

Science.gov (United States)

Denk, Nora; Fritsche, Jens; Reese, Sven

2011-05-01

To evaluate the effect of UV-blocking soft contact lenses in treatment for chronic superficial keratitus (CSK). Twenty six dogs with CSK were treated continuously with UV-blocking contact lenses for 6 months. A contact lens was placed on one eye of each dog; the other eye remained without a lens as a control eye. After this primary study, five of the dogs were further treated and they wore then contact lenses in both eyes. Continuously, all patients were concurrently treated topically with cyclosporine. The contact lenses were changed every 4 weeks and an ophthalmic examination performed. Evaluation criteria included corneal alterations as pigmentation, edema, pannus and vascularization. To determine the transmittance characteristics of the contact lenses before and after use, 32 contact lenses were measured with a UV-vis-NIR spectrophotometer. Pigmentation increased in eyes wearing lenses and in control eyes over the evaluation period of 6 months. Corneal edema increased in the eyes wearing lenses, but remained unaffected in the control eyes. A significant difference in the incidence of pannus and the extent of corneal vascularisation could not be evaluated. Adverse effects were noted in six cases (corneal edema and vascularisation, conjunctivitis, blepharospasm). All new lenses studied reduced UV-radiation to a safe level, whereas used lenses did not maintain their transmittance characteristics. No positive effect of UV-blocking contact lenses could be proven with the study design used. © 2011 American College of Veterinary Ophthalmologists.

MUSE integral-field spectroscopy towards the Frontier Fields Cluster Abell S1063

DEFF Research Database (Denmark)

Karman, W.; Caputi, K. I.; Grillo, C.

2015-01-01

We present the first observations of the Frontier Fields Cluster Abell S1063 taken with the newly commissioned Multi Unit Spectroscopic Explorer (MUSE) integral field spectrograph. Because of the relatively large field of view (1 arcmin^2), MUSE is ideal to simultaneously target multiple galaxies...... the cluster, we find 17 galaxies at higher redshift, including three previously unknown Lyman-alpha emitters at z>3, and five multiply-lensed galaxies. We report the detection of a new z=4.113 multiply lensed galaxy, with images that are consistent with lensing model predictions derived for the Frontier...... of scientific topics that can be addressed with a single MUSE pointing. We conclude that MUSE is a very efficient instrument to observe galaxy clusters, enabling their mass modelling, and to perform a blind search for high-redshift galaxies....

Class B0631+519: Last of the Class Lenses

Energy Technology Data Exchange (ETDEWEB)

York, Tom; Jackson, N.; Browne, I.W.A.; Koopmans, L.V.E.; McKean, J.P.; Norbury, M.A.; Biggs, A.D.; Blandford, R.D.; de Bruyn, A.G.; Fassnacht, C.D.; Myers, S.T.; Pearson, T.J.; Phillips, P.M.; Readhead, A.C.S.; Rusin, D.; Wilkinson, P.N.; /Jodrell Bank /Kapteyn Astron. Inst., Groningen /UC, Davis /JIVE, Dwingeloo /KIPAC, Menlo Park /NFRA,

2005-05-31

We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and indicates that the small irregular galaxy has a (localized) effect on the flux density distribution in the Einstein ring at the 5-10% level.

Rotation of the cosmic microwave background polarization from weak gravitational lensing.

Science.gov (United States)

Dai, Liang

2014-01-31

When a cosmic microwave background (CMB) photon travels from the surface of last scatter through spacetime metric perturbations, the polarization vector may rotate about its direction of propagation. This gravitational rotation is distinct from, and occurs in addition to, the lensing deflection of the photon trajectory. This rotation can be sourced by linear vector or tensor metric perturbations and is fully coherent with the curl deflection field. Therefore, lensing corrections to the CMB polarization power spectra as well as the temperature-polarization cross correlations due to nonscalar perturbations are modified. The rotation does not affect lensing by linear scalar perturbations, but needs to be included when calculations go to higher orders. We present complete results for weak lensing of the full-sky CMB power spectra by general linear metric perturbations, taking into account both deflection of the photon trajectory and rotation of the polarization. For the case of lensing by gravitational waves, we show that the B modes induced by the rotation largely cancel those induced by the curl component of deflection.

Performance of Lotrafilcon B silicone hydrogel contact lenses in experienced low-Dk/t daily lens wearers.

Science.gov (United States)

Dillehay, Sally M; Miller, Marian B

2007-11-01

The silicone hydrogel lens O2OPTIX with a Dk/t of 138 (at -3.00 diopters [D]) was evaluated and compared with patients' habitual low-Dk/t lenses. This large, multisite (United States and Canada), single-masked study enrolled experienced daily-wear, low-Dk/t, 2-week replacement soft contact lens wearers. Subjects underwent baseline evaluations and were fitted with O2OPTIX lenses for a 2-week period. After 2 weeks, subjects returned for assessment versus their habitual lenses. Data for 760 subjects were analyzed. The overall average habitual contact lens power was -3.13 D, and the average O2OPTIX lens power was -3.22 D. Biomicroscopy evaluations showed improvements in signs related to corneal health with O2OPTIX. Conjunctival and limbal redness, corneal neovascularization, corneal edema, and corneal and conjunctival staining all decreased significantly from baseline. O2OPTIX lenses performed better than habitual lenses in terms of comfort, symptoms, and overall preference. When wearing O2OPTIX lenses, significantly fewer subjects reported problems compared to their habitual lenses, including uncomfortable lens wear (-20.3%), redness (-44.5%), dryness during the day (-40.2%), and dryness at the end of the day (-34.4%); 47.9% reported that they could wear O2OPTIX lenses longer than their habitual lenses. At the end of study, among those with a preference, a significantly greater proportion of patients (60.3%) preferred O2OPTIX lenses to their habitual lenses. Daily wear of O2OPTIX lenses resulted in improvements in corneal signs of health and patient symptoms and provided excellent vision and comfort. O2OPTIX lenses were preferred by subjects over their habitual lenses.

Antifouling leaching technique for optical lenses

Science.gov (United States)

Strahle, William J.; Perez, C. L.; Martini, Marinna A.

1994-01-01

The effectiveness of optical lenses deployed in water less than 100 m deep is significantly reduced by biofouling caused by the settlement of macrofauna, such as barnacles, hydroids, and tunicates. However, machineable porous plastic rings can be used to dispense antifoulant into the water in front of the lens to retard macrofaunal growth without obstructing the light path. Unlike coatings which can degrade the optical performance, antifouling rings do not interfere with the instrument optics. The authors have designed plastic, reusable cup-like antifouling rings to slip over the optical lenses of a transmissometer. These rings have been used for several deployments on shallow moorings in Massachusetts Bay, MA and have increased the time before fouling degrades optical characteristics

Probing the cosmic distance duality relation using time delay lenses

Energy Technology Data Exchange (ETDEWEB)

Rana, Akshay; Mahajan, Shobhit; Mukherjee, Amitabha [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Jain, Deepak [Deen Dayal Upadhyaya College, University of Delhi, Sector-3, Dwarka, New Delhi 110078 (India); Holanda, R.F.L., E-mail: montirana1992@gmail.com, E-mail: djain@ddu.du.ac.in, E-mail: shobhit.mahajan@gmail.com, E-mail: amimukh@gmail.com, E-mail: holanda@uepb.edu.br [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Aracaju—SE (Brazil)

2017-07-01

The construction of the cosmic distance-duality relation (CDDR) has been widely studied. However, its consistency with various new observables remains a topic of interest. We present a new way to constrain the CDDR η( z ) using different dynamic and geometric properties of strong gravitational lenses (SGL) along with SNe Ia observations. We use a sample of 102 SGL with the measurement of corresponding velocity dispersion σ{sub 0} and Einstein radius θ {sub E} . In addition, we also use a dataset of 12 two image lensing systems containing the measure of time delay Δ t between source images. Jointly these two datasets give us the angular diameter distance D {sub A} {sub ol} of the lens. Further, for luminosity distance, we use the 740 observations from JLA compilation of SNe Ia. To study the combined behavior of these datasets we use a model independent method, Gaussian Process (GP). We also check the efficiency of GP by applying it on simulated datasets, which are generated in a phenomenological way by using realistic cosmological error bars. Finally, we conclude that the combined bounds from the SGL and SNe Ia observation do not favor any deviation of CDDR and are in concordance with the standard value (η=1) within 2σ confidence region, which further strengthens the theoretical acceptance of CDDR.

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

Science.gov (United States)

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended. PMID:24833224

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

Directory of Open Access Journals (Sweden)

Debarun Dutta

2013-11-01

Full Text Available Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in numbers of bacteria that adhered to hydrogel etafilcon A or silicone hydrogel senofilcon A contact lenses. Pseudomonas aeruginosa adhered in higher numbers compared to Staphylococcus aureus. Within a genera/species, adhesion of different bacterial strains did not differ appreciably. The size of initial inoculum, nutritional content of media, and incubation period played significant roles in bacterial adhesion to lenses. A set of in vitro assay conditions to help standardize adhesion between studies have been recommended.

Analysis of coronal H I Lyman alpha measurements from a rocket flight on 1979 April 13

International Nuclear Information System (INIS)

Withbroe, G.L.; Kohl, J.L.; Weiser, H.; Noci, G.; Munro, R.H.

1982-01-01

Measurements of the profiles of resonantly scattered hydrogen Lyman-α coronal radiation have been used to determine hydrogen kinetic temperatures from 1.5 to 4 R/sub sun/ from Sun center in a quiet region of the corona. Proton temperatures derived from the line widths decrease with height from 2.6 x 10 6 K at r = 1.5 R/sub sun/ to 1.2 x 10 6 K at r = 4 R/sub sun/. These measurements combined with temperatures for lower heights determined from earlier Skylab and eclipse data suggest that there is a maximum in the quiet coronal proton temperature at about 1.5 R/sub sun/. Comparison of measured Lyman-α intensities with those calculated using a representative model for the radial variation of the coronal electron density provides information on the magnitude of the electron temperature gradient and suggests that the solar wind flow was subsonic for r<4 R/sub sun/ in the observed region. Comparison of the measured kinetic temperatures to the predictions of a simple two fluid model suggests that there is a small amount of proton heating and/or a nonthermal contribution to the motions of coronal protons between 1.5 and 4 R/sub sun/

Improvements to the Root Finding Algorithm in VBBinaryLensing

Science.gov (United States)

Heintz, Tyler; Hoag, Ava; Bozza, Valerio; Oberst, Thomas

2018-01-01

VBBinaryLensing is the leading code for fitting magnification maps to microlensing events by binary lenses, most especially for exoplanet discoveries. The majority of the code’s runtime is devoted to finding roots of a fifth order complex polynomial arising from the binary lens equation. This is currently accomplished via the ZROOTS subroutine, which employs Laguerre’s method. Skowron and Gould’s (2012) algorithm, which employs a combination of Laguerre’s and Newton’s methods, presents the possibility of faster runtimes. We introduce a C++ translation of Skowron and Gould’s algorithm and test it as a replacement for ZROOTS in VBBinaryLensing. We find that this new implementation both reduces the time spent finding roots and makes the code more robust in extreme regimes.

Copolymers for soft hydrophilic contact lenses: development and investigations

International Nuclear Information System (INIS)

Schwach, G.W.

1978-05-01

Low esters of methacrylic acid which may be polymerized by different methods are used predominantly for producing soft hydrophilic contact lenses. Compounds of the vinyl-type often are added to improve the optical and mechanical qualities. Composition as well as possibilities of polymerization by irradiation were tested so long until copolymers were found which finally allowed the production of soft hydrophilic contact lenses. Swelling characteristics and permeability of the different elastomeres are to be investigated in order to guarantee sufficient compatibility of contact lenses. Contamination of the lens materials by microorganisms is also a point of special interest. The effects on the hydrophilic contact lens-copolymers by different substances used for cleaning and storage solutions have been investigated as well. (author)

Adaptive silicone-membrane lenses: planar vs. shaped membrane

CSIR Research Space (South Africa)

Schneider, F

2009-08-01

Full Text Available Engineering, Georges-Koehler-Allee 102, Freiburg 79110, Germany florian.schneider@imtek.uni-freiburg.de ABSTRACT We compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a...-membrane lenses: planar vs. shaped membrane Florian Schneider1,2, Philipp Waibel2 and Ulrike Wallrabe2 1 CSIR, Materials Science and Manufacturing, PO Box 395, Pretoria 0001, South Africa 2 University of Freiburg – IMTEK, Department of Microsystems...

Bilateral spontaneous subluxation of scleral-fixated intraocular lenses.

Science.gov (United States)

Assia, Ehud I; Nemet, Arie; Sachs, Dani

2002-12-01

Two young men with primary ectopic lenses had intracapsular cataract extraction and scleral fixation of posterior chamber intraocular lenses (PC IOLs) using 10-0 polypropylene sutures tied to the IOL eyelets. Three to 9 years after implantation, spontaneous IOL vertical subluxation occurred in all 4 eyes (5 IOL loops), probably because of suture breakage. Late subluxation of a sutured IOL may occur several years after implantation. Double fixation and thicker sutures should be considered, especially in young patients.

Scientific visualization of gravitational lenses

International Nuclear Information System (INIS)

Magallon, M.

1999-01-01

Concepts related to gravitational lenses are discussed and applied to develop an interactive visualization tool that allow us to investigate them. Optimization strategies were performed to elaborate the tool. Some results obtained from the application of the tool are shown [es

Prediction of radiation-induced liver disease by Lyman normal-tissue complication probability model in three-dimensional conformal radiation therapy for primary liver carcinoma

International Nuclear Information System (INIS)

Xu ZhiYong; Liang Shixiong; Zhu Ji; Zhu Xiaodong; Zhao Jiandong; Lu Haijie; Yang Yunli; Chen Long; Wang Anyu; Fu Xiaolong; Jiang Guoliang

2006-01-01

Purpose: To describe the probability of RILD by application of the Lyman-Kutcher-Burman normal-tissue complication (NTCP) model for primary liver carcinoma (PLC) treated with hypofractionated three-dimensional conformal radiotherapy (3D-CRT). Methods and Materials: A total of 109 PLC patients treated by 3D-CRT were followed for RILD. Of these patients, 93 were in liver cirrhosis of Child-Pugh Grade A, and 16 were in Child-Pugh Grade B. The Michigan NTCP model was used to predict the probability of RILD, and then the modified Lyman NTCP model was generated for Child-Pugh A and Child-Pugh B patients by maximum-likelihood analysis. Results: Of all patients, 17 developed RILD in which 8 were of Child-Pugh Grade A, and 9 were of Child-Pugh Grade B. The prediction of RILD by the Michigan model was underestimated for PLC patients. The modified n, m, TD 5 (1) were 1.1, 0.28, and 40.5 Gy and 0.7, 0.43, and 23 Gy for patients with Child-Pugh A and B, respectively, which yielded better estimations of RILD probability. The hepatic tolerable doses (TD 5 ) would be MDTNL of 21 Gy and 6 Gy, respectively, for Child-Pugh A and B patients. Conclusions: The Michigan model was probably not fit to predict RILD in PLC patients. A modified Lyman NTCP model for RILD was recommended

Noise estimates for measurements of weak lensing from the Ly α forest

Science.gov (United States)

Metcalf, R. Benton; Croft, Rupert A. C.; Romeo, Alessandro

2018-06-01

Lensing changes the apparent separation between pixels in the Ly α forest of separate quasars or high-redshift objects by changing their observed positions on the sky. This changes the implied correlations in the absorption and in particular makes the Ly α forest correlation function, or power spectrum, locally anisotropic in the plane of the sky. We have proposed a method for measuring weak lensing using this effect. Here, we estimate the noise expected in weak lensing maps and power spectra for different sets of observational parameters. We find that surveys of the size and quality of the ones being done today and ones planned for the future will be able to measure the lensing power spectrum at a source redshift of z ≃ 2.5 with high precision and even be able to image the distribution of foreground matter with high fidelity on degree scales. For example, we predict that Ly α forest lensing measurements from the DESI and WEAVE surveys should yield the mass fluctuation amplitude with a statistical error of ˜3 per cent, eBOSS ˜6 per cent. and the proposed MSE survey less than 1 per cent. By dividing the redshift range into multiple bins, some tomographic lensing information should be accessible as well. This would allow for cosmological lensing measurements at higher redshift than are accessible with galaxy shear surveys and correspondingly better constraints on the evolution of dark energy at relatively early times.

EFFECT OF HALO BIAS AND LYMAN LIMIT SYSTEMS ON THE HISTORY OF COSMIC REIONIZATION

International Nuclear Information System (INIS)

Kaurov, Alexander A.; Gnedin, Nickolay Y.

2013-01-01

We extend the existing analytical model of reionization by Furlanetto et al. to include the biasing of reionization sources and additional absorption by Lyman limit systems. Both effects enhance the original model in non-trivial ways, but do not change its qualitative features. Our model is, by construction, consistent with the observed evolution of the galaxy luminosity function at z ∼ 6 galaxies, the inadequacy of simulations and/or some of the observational constraints, or indicates an additional source of ionizing radiation at z > 8 remains to be seen.

Emission-angle and polarization-rotation effects in the lensed CMB

Energy Technology Data Exchange (ETDEWEB)

Lewis, Antony [Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH (United Kingdom); Hall, Alex [Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ (United Kingdom); Challinor, Anthony, E-mail: antony@cosmologist.info, E-mail: ahall@roe.ac.uk, E-mail: a.d.challinor@ast.cam.ac.uk [Institute of Astronomy and Kavli Institute for Cosmology, Madingley Road, Cambridge, CB3 0HA (United Kingdom)

2017-08-01

Lensing of the CMB is an important effect, and is usually modelled by remapping the unlensed CMB fields by a lensing deflection. However the lensing deflections also change the photon path so that the emission angle is no longer orthogonal to the background last-scattering surface. We give the first calculation of the emission-angle corrections to the standard lensing approximation from dipole (Doppler) sources for temperature and quadrupole sources for temperature and polarization. We show that while the corrections are negligible for the temperature and E-mode polarization, additional large-scale B-modes are produced with a white spectrum that dominates those from post-Born field rotation (curl lensing). On large scales about one percent of the total lensing-induced B-mode amplitude is expected to be due to this effect. However, the photon emission angle does remain orthogonal to the perturbed last-scattering surface due to time delay, and half of the large-scale emission-angle B modes cancel with B modes from time delay to give a total contribution of about half a percent. While not important for planned observations, the signal could ultimately limit the ability of delensing to reveal low amplitudes of primordial gravitational waves. We also derive the rotation of polarization due to multiple deflections between emission and observation. The rotation angle is of quadratic order in the deflection angle, and hence negligibly small: polarization typically rotates by less than an arcsecond, orders of magnitude less than a small-scale image rotates due to post-Born field rotation (which is quadratic in the shear). The field-rotation B modes dominate the other effects on small scales.

Contact lenses purchased over the internet place individuals potentially at risk for harmful eye care practices.

Science.gov (United States)

Fogel, Joshua; Zidile, Chaya

2008-01-01

Individuals are increasingly purchasing contact lenses over the Internet. No studies exist regarding Internet purchase of contact lenses and eye care health practices. One hundred fifty-one college students were surveyed regarding contact lenses purchase category (doctor's office, store, Internet). Pearson chi-square analyses compared purchase category with responses regarding U.S. Food and Drug Administration (FDA) recommendations for purchasing contact lenses online. Analysis of variance compared contact lenses purchase category with the Time Pressure Scale (TPS). Also, correlation analyses compared the TPS with Internet eye-health statements. Contact lens purchase categories included doctor's office (43.0%), store (55.0%), and Internet (22.5%), with individuals purchasing at multiple venues. With regard to the FDA recommendations, those who purchased contact lenses at a doctor's office more often adhered to the recommendations, whereas those who purchased contact lenses at a store or the Internet did so less often. Those who purchased contact lenses over the Internet had significantly higher TPS scores. In addition, higher TPS scores were significantly correlated with various statements regarding the Internet. Those who purchase contact lenses via the Internet or store do not follow a number of FDA contact lenses recommendations. Also, those with higher TPS scores trust possible non-evidence-based contact lenses Internet information. Implications with regard to the Fairness to Contact Lens Consumers Act are discussed.

Soft contact lenses: Basic characteristics, advantages and complications associated with their use

Directory of Open Access Journals (Sweden)

Milosavljević Miloš

2016-01-01

Full Text Available Soft contact lenses have an important place in ophthalmology, both for the correction of refractive anomalies and tor the treatment of some eye diseases. From the moment when adequately biocompatible materials were found, for a very sensitive environment such as the human eye, from early 60s of the 20th century, starts irrepressible expansion of soft contact lenses. The reason for this expansion of soft contact lenses lies in advantages they undoubtedly have in comparison to glasses, but also in comparison to hard and semi-hard contact lenses. Unfortunately, in parallel with the increasing number of users of this type of optical aids, increases the incidence of complications that can arise. Complications can be very diverse in nature and severity, and they can be classified into three major groups: symptoms of eye dryness, infections and allergic-toxic complications. Symptoms of dry eye are very common for users of contact lenses, and their occurrence is especially provoked by certain factors, such as cigarette smoke or prolonged watching the computer screen or TV. These complications are usually not so dangerous and can easily be solved by applying artificial tears. Infections are not so common and occur as a result of inadequate maintenance of contact lenses. If the symptoms are recognized early, infections are mostly stopped at the level of conjunctivitis and are treated fairly quickly and easily. Otherwise, the infection can progress to ulcerative keratitis, the most severe complication of inadequate application of soft contact lenses, and in some cases it can even lead to blindness. Allergic-toxic complications generally occur in susceptible persons and their occurrence in most cases means contraindication for further wearing of soft contact lenses. This case report underlines possible role of rheumatoid factor in estimation of the patient's response to administered therapy.

Gravitational lensing by eigenvalue distributions of random matrix models

Science.gov (United States)

Martínez Alonso, Luis; Medina, Elena

2018-05-01

We propose to use eigenvalue densities of unitary random matrix ensembles as mass distributions in gravitational lensing. The corresponding lens equations reduce to algebraic equations in the complex plane which can be treated analytically. We prove that these models can be applied to describe lensing by systems of edge-on galaxies. We illustrate our analysis with the Gaussian and the quartic unitary matrix ensembles.

Detecting Gravitational Lensing of the Cosmic Microwave Background by Galaxy Clusters

Energy Technology Data Exchange (ETDEWEB)

Baxter, Eric Jones [Univ. of Chicago, IL (United States)

2014-08-01

Clusters of galaxies gravitationally lens the Cosmic Microwave Background (CMB) leading to a distinct signal in the CMB on arcminute scales. Measurement of the cluster lensing effect offers the exciting possibility of constraining the masses of galaxy clusters using CMB data alone. Improved constraints on cluster masses are in turn essential to the use of clusters as cosmological probes: uncertainties in cluster masses are currently the dominant systematic affecting cluster abundance constraints on cosmology. To date, however, the CMB cluster lensing signal remains undetected because of its small magnitude and angular size. In this thesis, we develop a maximum likelihood approach to extracting the signal from CMB temperature data. We validate the technique by applying it to mock data designed to replicate as closely as possible real data from the South Pole Telescope’s (SPT) Sunyaev-Zel’dovich (SZ) survey: the effects of the SPT beam, transfer function, instrumental noise and cluster selection are incorporated. We consider the effects of foreground emission on the analysis and show that uncertainty in amount of foreground lensing results in a small systematic error on the lensing constraints. Additionally, we show that if unaccounted for, the SZ effect leads to unacceptably large biases on the lensing constraints and develop an approach for removing SZ contamination. The results of the mock analysis presented here suggest that a 4σ first detection of the cluster lensing effect can be achieved with current SPT-SZ data.

Weak gravitational lensing as a method to constrain unstable dark matter

International Nuclear Information System (INIS)

Wang Meiyu; Zentner, Andrew R.

2010-01-01

The nature of the dark matter remains a mystery. The possibility of an unstable dark matter particle decaying to invisible daughter particles has been explored many times in the past few decades. Meanwhile, weak gravitational lensing shear has gained a lot of attention as a probe of dark energy, though it was previously considered a dark matter probe. Weak lensing is a useful tool for constraining the stability of the dark matter. In the coming decade a number of large galaxy imaging surveys will be undertaken and will measure the statistics of cosmological weak lensing with unprecedented precision. Weak lensing statistics are sensitive to unstable dark matter in at least two ways. Dark matter decays alter the matter power spectrum and change the angular diameter distance-redshift relation. We show how measurements of weak lensing shear correlations may provide the most restrictive, model-independent constraints on the lifetime of unstable dark matter. Our results rely on assumptions regarding nonlinear evolution of density fluctuations in scenarios of unstable dark matter and one of our aims is to stimulate interest in theoretical work on nonlinear structure growth in unstable dark matter models.

SUBARU WEAK-LENSING STUDY OF A2163: BIMODAL MASS STRUCTURE

International Nuclear Information System (INIS)

Okabe, N.; Bourdin, H.; Mazzotta, P.; Maurogordato, S.

2011-01-01

We present a weak-lensing analysis of the merging cluster A2163 using Subaru/Suprime-Cam and CFHT/Mega-Cam data and discuss the dynamics of this cluster merger, based on complementary weak-lensing, X-ray, and optical spectroscopic data sets. From two-dimensional multi-component weak-lensing analysis, we reveal that the cluster mass distribution is well described by three main components including the two-component main cluster A2163-A with mass ratio 1:8, and its cluster satellite A2163-B. The bimodal mass distribution in A2163-A is similar to the galaxy density distribution, but appears as spatially segregated from the brightest X-ray emitting gas region. We discuss the possible origins of this gas-dark-matter offset and suggest the gas core of the A2163-A subcluster has been stripped away by ram pressure from its dark matter component. The survival of this gas core from the tidal forces exerted by the main cluster lets us infer a subcluster accretion with a non-zero impact parameter. Dominated by the most massive component of A2163-A, the mass distribution of A2163 is well described by a universal Navarro-Frenk-White profile as shown by a one-dimensional tangential shear analysis, while the singular-isothermal sphere profile is strongly ruled out. Comparing this cluster mass profile with profiles derived assuming intracluster medium hydrostatic equilibrium (H.E.) in two opposite regions of the cluster atmosphere has allowed us to confirm the prediction of a departure from H.E. in the eastern cluster side, presumably due to shock heating. Yielding a cluster mass estimate of M 500 = 11.18 +1.64 –1.46 × 10 14 h –1 M ☉ , our mass profile confirms the exceptionally high mass of A2163, consistent with previous analyses relying on the cluster dynamical analysis and Y X mass proxy.

Star Formation at z = 2.481 in the Lensed Galaxy SDSS J1110 = 6459. I. Lens Modeling and Source Reconstruction

Science.gov (United States)

Johnson, Traci L.; Sharon, Keren; Gladders, Michael D.; Rigby, Jane R.; Bayliss, Matthew B.; Wuyts, Eva; Whitaker, Katherine E.; Florian, Michael; Murray, Katherine T.

2017-07-01

Using the combined resolving power of the Hubble Space Telescope and gravitational lensing, we resolve star-forming structures in a z˜ 2.5 galaxy on scales much smaller than the usual kiloparsec diffraction limit of HST. SGAS J111020.0+645950.8 is a clumpy, star-forming galaxy lensed by the galaxy cluster SDSS J1110+6459 at z=0.659, with a total magnification ˜ 30× across the entire arc. We use a hybrid parametric/non-parametric strong lensing mass model to compute the deflection and magnification of this giant arc, reconstruct the light distribution of the lensed galaxy in the source plane, and resolve the star formation into two dozen clumps. We develop a forward-modeling technique to model each clump in the source plane. We ray-trace the model to the image plane, convolve with the instrumental point-spread function (PSF), and compare with the GALFIT model of the clumps in the image plane, which decomposes clump structure from more extended emission. This technique has the advantage, over ray-tracing, of accounting for the asymmetric lensing shear of the galaxy in the image plane and the instrument PSF. At this resolution, we can begin to study star formation on a clump-by-clump basis, toward the goal of understanding feedback mechanisms and the buildup of exponential disks at high redshift. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program # 13003.

Multipole lenses with implicit poles and with harmonic distribution of current density in a coil

International Nuclear Information System (INIS)

Skachkov, V.S.

1984-01-01

General theory of the multipole lense with implicit poles is presented. The thickness of lense coil is finite. Current density distribution in the coil cross section is harmonic in the azimuth direction and arbitrary in the radial one. The calculation of yoke contribution in the lence field is given. Two particular lense variants differing from each other in the method of current density radial distribution are considered and necessary calculated relations for the lense with and without yoke ar presented. A comparative analysis of physical and technological peculiarities of these lenses is performed

A new case of gravitational lensing

International Nuclear Information System (INIS)

Surdej, J.; Swings, J.-P.; Borgeest, U.; Kayser, R.; Refsdal, S.; Courvoisier, T.J.-L.; Kellermann, K.I.; Kuehr, H.

1987-01-01

The authors report a brief description of a gravitational lens system UM673 = Q0142 - 100 = PHL3703. It consists of two images, A and B, separated by 2.2 arc s at a redshift zsub(q) = 2.719. The lensing galaxy has also been found. It lies very near the line connecting the two QSO (quasi-stellar objects) images, approx. 0.8 arc s from the fainter one. Application of gravitational optometry to this system leads to a value Msub(o) or approx. = 2.4 x 10 11 M solar masses for the mass of the lensing galaxy and to Δt approx. 7 weeks for the most likely travel-time difference between the two light paths to the QSO. (author)

THE MICROLENSING PROPERTIES OF A SAMPLE OF 87 LENSED QUASARS

International Nuclear Information System (INIS)

Mosquera, A. M.; Kochanek, C. S.

2011-01-01

Gravitational microlensing is a powerful tool for probing the physical properties of quasar accretion disks and properties of the lens galaxy such as its dark matter fraction and mean stellar mass. Unfortunately, the number of lensed quasars (∼90) exceeds our monitoring capabilities. Thus, estimating their microlensing properties is important for identifying good microlensing candidates as well as for the expectations of future surveys. In this work, we estimate the microlensing properties of a sample of 87 lensed quasars. While the median Einstein radius crossing timescale is 20.6 years, the median source crossing timescale is 7.3 months. Broadly speaking, this means that on ∼10 year timescales roughly half the lenses will be quiescent, with the source in a broad demagnified valley, and roughly half will be active with the source lying in the caustic ridges. We also found that the location of the lens system relative to the cosmic microwave background dipole has a modest effect on microlensing timescales, and in theory microlensing could be used to confirm the kinematic origin of the dipole. As a corollary of our study we analyzed the accretion rate parameters in a sub-sample of 32 lensed quasars. At fixed black hole mass, it is possible to sample a broad range of luminosities (i.e., Eddington factors) if it becomes feasible to monitor fainter lenses.

Measured operational neutron energies of compound refractive lenses

Energy Technology Data Exchange (ETDEWEB)

Park, H. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States)]. E-mail: hpark@adelphitech.com; Cremer, J.T. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Piestrup, M.A. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Gary, C.K. [Adelphi Technology Inc., 981-B Industrial Road, San Carlos, CA 94070 (United States); Hjelm, Rex P. [Los Alamos Neutron Science Center (LANSCE), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Sellyey, W.C.L.J. [Los Alamos Neutron Science Center (LANSCE), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Pantell, R.H. [Department of Electrical Engineering, Stanford University, Stanford, CA 94305 (United States)

2006-10-15

The characteristics of two compound refractive lenses (CRLs) have been measured using a broadband spallation neutron source. One CRL consists of a stack of 98 biconcave, spherical lenses made of MgF{sub 2}, and another consists of 198 biconcave, spherical lenses made of Al. The bandwidth of the spallation source included wavelengths from 1.5 A to 15.7 A that we could use to test the CRLs. The MgF{sub 2} CRL was found to be useful from 9 to 15 A with the maximum transmission around 13 A, whereas the Al CRL was found to give good transmission around 5-15 A, with the maximum transmission around 8 A. Spectra with Al lens and MgF{sub 2} CRLs show multiple transmission dips due to Bragg diffraction of the microcrystal structure of the lens materials (Al or MgF{sub 2}). These measurements helped characterize the CRLs for possible applications at shorter wavelengths than previously used.

A Laboratory Assessment of Factors That Affect Bacterial Adhesion to Contact Lenses

OpenAIRE

Dutta, Debarun; Willcox, Mark DP

2013-01-01

Adhesion of pathogenic microbes, particularly bacteria, to contact lenses is implicated in contact lens related microbial adverse events. Various in vitro conditions such as type of bacteria, the size of initial inoculum, contact lens material, nutritional content of media, and incubation period can influence bacterial adhesion to contact lenses and the current study investigated the effect of these conditions on bacterial adhesion to contact lenses. There was no significant difference in num...

SPECTROSCOPIC CONFIRMATION OF FAINT LYMAN BREAK GALAXIES NEAR REDSHIFT FIVE IN THE HUBBLE ULTRA DEEP FIELD