WorldWideScience

Sample records for luminosity factor

  1. Quality Factor for the Hadronic Calorimeter in High Luminosity Conditions

    CERN Document Server

    Seixas, Jose; The ATLAS collaboration; Manhaes de Andrade Filho, Luciano; Sotto-Maior-Peralva, Bernardo

    2014-01-01

    The Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of ATLAS experiment and has about 10,000 eletronic channels. An Optimal Filter (OF) has been used to estimate the energy sampled by the calorimeter and applies a Quality Factor (QF) for signal acceptance. An approach using Matched Filter (MF) has also been pursued. In order to cope with the luminosity rising foreseen for LHC operation upgrade, different algorithms have been developed. Currently, the OF measure for signal acceptance is implemented through a chi-square test. At a low luminosity scenario, such QF measure has been used as a way to describe how the acquired signal is compatible to the pulse shape pattern. However, at high-luminosity conditions, due to pile up, this QF acceptance is no longer possible when OF is employed, and the QF becomes a measure to indicate whether the reconstructed signal suffers or not from pile up. Methods are being developed in order to recover the superposed information, and the QF may be us...

  2. Luminosity and Redshift Dependence of the Covering Factor of AGNs viewed with WISE and SDSS

    CERN Document Server

    Toba, Yoshiki; Matsuhara, Hideo; Malkan, Matthew A; Gandhi, Poshak; Nakagawa, Takao; Isobe, Naoki; Shirahata, Mai; Oi, Nagisa; Ohyama, Youichi; Takita, Satoshi; Yamauchi, Chisato; Yano, Kenichi

    2014-01-01

    In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) (i) on the mid-infrared (MIR) luminosity and (ii) on the redshift. We constructed 12- and 22-micron luminosity functions (LFs) at 0.006 < z < 0.3 using the Wide-field Infrared Survey Explorer} (WISE) data. Combining the WISE catalog with the Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 micron and 25,721 galaxies at 22 micron for spectroscopic classification. We then identified 16,355 AGNs at 12 micron and 4,683 AGNs at 22 micron by their optical emission lines and cataloged classifications in the SDSS. Following that, we estimated the CF as the fraction of type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that (i) the CF decreased with increasing MIR luminosity, regardless of the choice of type 2 AGN classification criteria, and (ii) the CF did not change significantly ...

  3. Luminosity and redshift dependence of the covering factor of active galactic nuclei viewed with WISE and Sloan digital sky survey

    Energy Technology Data Exchange (ETDEWEB)

    Toba, Y.; Matsuhara, H. [Department of Space and Astronautical Science, the Graduate University for Advanced Studies (Sokendai), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Oyabu, S. [Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan); Malkan, M. A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Gandhi, P. [Department of Physics, Durham University, Durham DH1-3LE (United Kingdom); Nakagawa, T.; Isobe, N.; Shirahata, M.; Oi, N.; Takita, S.; Yano, K. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Ohyama, Y. [Institute of Astronomy and Astrophysics, Academia Sinica, P.O. Box 23-141, Taipei 10617 Taiwan (China); Yamauchi, C., E-mail: toba@ir.isas.jaxa.jp [Misato Observatory, 180 Matsugamine, Misato-cho, Kaiso-gun, Wakayama 640-1366 (Japan)

    2014-06-10

    In this work, we investigate the dependence of the covering factor (CF) of active galactic nuclei (AGNs) on the mid-infrared (MIR) luminosity and the redshift. We constructed 12 and 22 ?m luminosity functions (LFs) at 0.006 ?z ? 0.3 using Wide-field Infrared Survey Explorer (WISE) data. Combining the WISE catalog with Sloan Digital Sky Survey (SDSS) spectroscopic data, we selected 223,982 galaxies at 12 ?m and 25,721 galaxies at 22 ?m for spectroscopic classification. We then identified 16,355 AGNs at 12 ?m and 4683 AGNs at 22 ?m by their optical emission lines and cataloged classifications in the SDSS. Following that, we estimated the CF as the fraction of Type 2 AGN in all AGNs whose MIR emissions are dominated by the active nucleus (not their host galaxies) based on their MIR colors. We found that the CF decreased with increasing MIR luminosity, regardless of the choice of Type 2 AGN classification criteria, and the CF did not change significantly with redshift for z ? 0.2. Furthermore, we carried out various tests to determine the influence of selection bias and confirmed that similar dependences exist, even when taking these uncertainties into account. The luminosity dependence of the CF can be explained by the receding torus model, but the 'modified' receding torus model gives a slightly better fit, as suggested by Simpson.

  4. Light, Luminosity and the High Luminosity LHC

    CERN Multimedia

    2015-01-01

    Short interview to Lucio Rossi, project leader of the High Luminosity LHC, about the concept of light in physics, light and luminosity in particle accelerators and the High Luminosity LHC project. On the occasion of International Year of Light 2015.

  5. Luminosity measurement at AMY

    International Nuclear Information System (INIS)

    A precise measurement of a luminosity is required by experiments with high statistics. The largest sources of a systematic error of a luminosity measurement are an alignment of the tube chambers which measure a polar angle of Bhabha events and a higher order correction for the Bhabha cross section calculation. We describe a resent study for these uncertainties and how to reduce the systematic errors from these sources. The total systematic error of the luminosity measurement of 1.8% can be reduced to 1.0% by this study. (author)

  6. Colors, Luminosity Function and Counts of Galaxies

    OpenAIRE

    Saracco, P.; Chincarini, G.; Iovino, A.

    1995-01-01

    Standard models for deep galaxy counts are based on luminosity functions (LF) with relatively flat faint end ($\\alpha\\sim-1.0$). Galaxy counts in the B--band exceed the prediction of such models by a factor of 2 to more than 5, forcing the introduction of strong luminosity and/or density evolution. Recently Marzke et al. (1994a) using the CfA redshift survey sample find that the number of galaxies in the range $-16

  7. Luminosity Studies in ATLAS

    CERN Document Server

    Are Sivertsen, Traeet

    2015-01-01

    During the course of this summer I've been tasked with many dierent assignments working with the ATLAS Luminosity Taskforce. My main project was related to updating a PyROOT script that in Run1 was responsible for making comparison plots of the measured luminosity of subsystem detectors at ATLAS, and making it compatible with the new les used to store the data. The main purpose of this script was to enable an easy method for which one could get a quick overview of the measured luminosity over many runs such that one could see the stability of the subsystem detectors. This is useful to determine if there is any issues with the detectors so that one could investigate it further. The comparison plots can now be seen on the 2015 Run Data Preparation webpage.

  8. properties and luminosity functions

    Directory of Open Access Journals (Sweden)

    Hektor Monteiro

    2007-01-01

    Full Text Available In this article, we present an investigation of a sample of 1072 stars extracted from the Villanova Catalog of Spectroscopically Identified White Dwarfs (2005 on-line version, studying their distribution in the Galaxy, their physical properties and their luminosity functions. The distances and physical properties of the white dwarfs are determined through interpolation of their (B-V or (b-y colors in model grids. The solar position relative to the Galactic plane, luminosity function, as well as separate functions for each white dwarf spectral type are derived and discussed. We show that the binary fraction does not vary significantly as a function of distance from the Galactic disk out to 100 pc. We propose that the formation rates of DA and non-DAs have changed over time and/or that DAs evolve into non-DA types. The luminosity functions for DAs and DBs have peaks possibly related to a star burst event.

  9. Luminosity determination at the Tevatron

    OpenAIRE

    Papadimitriou, Vaia

    2011-01-01

    In this paper we discuss the luminosity determination at the Tevatron. We discuss luminosity measurements by the machine as well as by using the luminosity detectors of the CDF and D0 experiments. We discuss the uncertainties of the measurements, the effort to maximize the initial and integrated luminosity, the challenges and the lessons learned.

  10. Hydrogen-Ion Potential of Antibiotics According to the Environment Factors Temperature and Luminosity / Potencial hidrogenionico de antimicrobianos, según los factores ambientales de temperatura y luminosidad / Potencial hidrogeniônico de antimicrobianos, segundo os fatores ambientais temperatura e luminosidade

    Scientific Electronic Library Online (English)

    Renata Maria Coelho, Crepaldi; Cíntia, Monteiro; Maria Angélica Sorgini, Peterlini; Mavilde da Luz Gonçalves, Pedreira.

    2010-04-01

    Full Text Available O objetivo deste estudo experimental foi medir o pH dos antibióticos de administração intravenosa ceftriaxona sódica, cloridrato de vancomicina, metronidazol, penicilina G potássica e sulfato de amicacina, após reconstituição com água destilada e diluição com NaCl 0,9%, ou soro glicosado 5%, conside [...] rando a influência da temperatura e luminosidade ambientais, assim como do tempo de exposição, no comportamento químico desses fármacos. Os resultados demonstraram variações que não ultrapassaram 1,0 valor de pH e que alguns antimicrobianos, eminentemente ácidos após a diluição, mantiveram esse comportamento em todas as situações estudadas, não sugerindo a influência de fatores ambientais no comportamento químico das soluções. Como alguns valores de pH encontrados podem contribuir para o desenvolvimento de flebite química e infiltração, é importante enfatizar para a prática clínica em saúde, a necessidade de conhecer as características das soluções de infusão intravenosa, considerando tipo de diluição e tempo de infusão. Abstract in spanish El objetivo de este estudio experimental fue medir el pH de los antibióticos de administración intravenosa ceftriaxona sódica, clorhidrato de vancomicina, metronidazol, penicilina G potásica y sulfato de amikacina, después de reconstitución con agua destilada y dilución con NaCl a 0,9%, o suero gluc [...] osado a 5%, considerando la influencia de la temperatura y luminosidad ambientales, así como el tiempo de exposición, en el comportamiento químico de esos fármacos. Los resultados demostraron variaciones que no ultrapasaron 1,0 (valor de pH) y que algunos antimicrobianos, eminentemente ácidos después de la dilución, mantuvieron ese comportamiento en todas las situaciones estudiadas, no sugiriendo la influencia de factores ambientales en el comportamiento químico de las soluciones. Considerando que algunos valores de pH encontrados pueden contribuir para el desarrollo de flebitis química e infiltración, es importante enfatizar que para la práctica clínica en salud, existe la necesidad de conocer las características de las soluciones de infusión intravenosa, considerando el tipo de dilución y el tiempo de infusión. Abstract in english The objective of this experimental study was to measure the pH of antibiotics administered by intravenous infusion - ceftriaxone sodium, vancomycin hydrochloride, metrodinazole, penicillin G potassium and amikacin sulfate - after reconstitution with sterile water and dilution with NaCl 0.9% or dextr [...] ose 5% in water, according to temperature and luminosity of the environment. The results showed that variation in the drugs' pH was less than 1.0 value and that some antibiotics remained acidic after dilution and maintained this chemical profile in all situations studied, suggesting that the studied environmental factors did not change the solutions' acid base characteristic. Some pH values measured characterize risk for the development of chemical phlebitis and infiltration, and it is important for clinical practice to emphasize the profile of intravenous solutions of antibiotics, considering method of dilution, and time to infusion.

  11. Hydrogen-Ion Potential of Antibiotics According to the Environment Factors Temperature and Luminosity Potencial hidrogenionico de antimicrobianos, según los factores ambientales de temperatura y luminosidad Potencial hidrogeniônico de antimicrobianos, segundo os fatores ambientais temperatura e luminosidade

    Directory of Open Access Journals (Sweden)

    Renata Maria Coelho Crepaldi

    2010-04-01

    Full Text Available The objective of this experimental study was to measure the pH of antibiotics administered by intravenous infusion - ceftriaxone sodium, vancomycin hydrochloride, metrodinazole, penicillin G potassium and amikacin sulfate - after reconstitution with sterile water and dilution with NaCl 0.9% or dextrose 5% in water, according to temperature and luminosity of the environment. The results showed that variation in the drugs' pH was less than 1.0 value and that some antibiotics remained acidic after dilution and maintained this chemical profile in all situations studied, suggesting that the studied environmental factors did not change the solutions' acid base characteristic. Some pH values measured characterize risk for the development of chemical phlebitis and infiltration, and it is important for clinical practice to emphasize the profile of intravenous solutions of antibiotics, considering method of dilution, and time to infusion.El objetivo de este estudio experimental fue medir el pH de los antibióticos de administración intravenosa ceftriaxona sódica, clorhidrato de vancomicina, metronidazol, penicilina G potásica y sulfato de amikacina, después de reconstitución con agua destilada y dilución con NaCl a 0,9%, o suero glucosado a 5%, considerando la influencia de la temperatura y luminosidad ambientales, así como el tiempo de exposición, en el comportamiento químico de esos fármacos. Los resultados demostraron variaciones que no ultrapasaron 1,0 (valor de pH y que algunos antimicrobianos, eminentemente ácidos después de la dilución, mantuvieron ese comportamiento en todas las situaciones estudiadas, no sugiriendo la influencia de factores ambientales en el comportamiento químico de las soluciones. Considerando que algunos valores de pH encontrados pueden contribuir para el desarrollo de flebitis química e infiltración, es importante enfatizar que para la práctica clínica en salud, existe la necesidad de conocer las características de las soluciones de infusión intravenosa, considerando el tipo de dilución y el tiempo de infusión.O objetivo deste estudo experimental foi medir o pH dos antibióticos de administração intravenosa ceftriaxona sódica, cloridrato de vancomicina, metronidazol, penicilina G potássica e sulfato de amicacina, após reconstituição com água destilada e diluição com NaCl 0,9%, ou soro glicosado 5%, considerando a influência da temperatura e luminosidade ambientais, assim como do tempo de exposição, no comportamento químico desses fármacos. Os resultados demonstraram variações que não ultrapassaram 1,0 valor de pH e que alguns antimicrobianos, eminentemente ácidos após a diluição, mantiveram esse comportamento em todas as situações estudadas, não sugerindo a influência de fatores ambientais no comportamento químico das soluções. Como alguns valores de pH encontrados podem contribuir para o desenvolvimento de flebite química e infiltração, é importante enfatizar para a prática clínica em saúde, a necessidade de conhecer as características das soluções de infusão intravenosa, considerando tipo de diluição e tempo de infusão.

  12. Results From the DAFNE High Luminosity Test

    International Nuclear Information System (INIS)

    The DAPHNE collider, based on a new collision scheme including Large Piwinsky angle and Crab-Waist, has been successfully commissioned and is presently delivering luminosity to the SIDDHARTA detector. Large crossing angle and Crab-Waist scheme proved to be effective in: (1) Increasing luminosity, now a factor 2.7 higher than in the past; and (2) controlling transverse beam blow-up due to the beam-beam. Work is in progress to reach the ultimate design luminosity goal 5.0 · 1032 cm-2s-1. The new collision scheme is the main design concept for a new project aimed at building a Super-B factory that is expected to achieve a luminosity of the order of 1036 cm-2 s-1 and it has been also taken into account to upgrade one of the LHC interaction regions.

  13. A luminosity model of RHIC gold runs

    International Nuclear Information System (INIS)

    In this note, we present a luminosity model for RHIC gold runs. The model is applied to the physics fills in 2007 run without cooling, and with the longitudinal cooling applied to one beam only. Having good comparison, the model is used to project a fill with the longitudinal cooling applied to both beams. Further development and possible applications of the model are discussed. To maximize the integrated luminosity, usually the higher beam intensity, smaller longitudinal and transverse emittance, and smaller ? are the directions to work on. In past 10 years, the RHIC gold runs have demonstrated a path toward this goal. Most recently, a successful commissioning of the bunched beam stochastic cooling, both longitudinal and transverse, has offered a chance of further RHIC luminosity improvement. With so many factors involved, a luminosity model would be useful to identify and project gains in the machine development. In this article, a preliminary model is proposed. In Section 2, several secondary factors, which are not yet included in the model, are identified based on the RHIC operation condition and experience in current runs. In Section 3, the RHIC beam store parameters used in the model are listed, and validated. In Section 4, the factors included in the model are discussed, and the luminosity model is presented. In Section 5, typical RHIC gold fills without cooling, and with partial cooling are used for comparison with the model. Then a projection of fills with more coolings is shown. In Section 6, further development of the model is discussed.

  14. A luminosity model of RHIC gold runs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Y.

    2011-11-01

    In this note, we present a luminosity model for RHIC gold runs. The model is applied to the physics fills in 2007 run without cooling, and with the longitudinal cooling applied to one beam only. Having good comparison, the model is used to project a fill with the longitudinal cooling applied to both beams. Further development and possible applications of the model are discussed. To maximize the integrated luminosity, usually the higher beam intensity, smaller longitudinal and transverse emittance, and smaller {beta} are the directions to work on. In past 10 years, the RHIC gold runs have demonstrated a path toward this goal. Most recently, a successful commissioning of the bunched beam stochastic cooling, both longitudinal and transverse, has offered a chance of further RHIC luminosity improvement. With so many factors involved, a luminosity model would be useful to identify and project gains in the machine development. In this article, a preliminary model is proposed. In Section 2, several secondary factors, which are not yet included in the model, are identified based on the RHIC operation condition and experience in current runs. In Section 3, the RHIC beam store parameters used in the model are listed, and validated. In Section 4, the factors included in the model are discussed, and the luminosity model is presented. In Section 5, typical RHIC gold fills without cooling, and with partial cooling are used for comparison with the model. Then a projection of fills with more coolings is shown. In Section 6, further development of the model is discussed.

  15. The Subdwarf Luminosity Function

    CERN Document Server

    Digby, A P; Cooke, J A; Reid, I N; Cannon, R D; Digby, Andrew P.; Hambly, Nigel C.; Cooke, John A.; Cannon, Russell D.

    2003-01-01

    Using data from the Sloan Digital Sky Survey Early Data Release and SuperCOSMOS Sky Survey scans of POSS-I plates we identify a sample of 2600 subdwarfs using reduced proper motion methods and strict selection criteria. This forms one of the largest and most reliable samples of candidate subdwarfs known, and enables us to determine accurate luminosity functions along many different lines of sight. We derive the subdwarf luminosity function with unprecedented accuracy to M_V <= 13, finding good agreement with recent local estimates but discrepancy with results for the more distant spheroid. This provides further evidence that the inner and outer parts of the stellar halo cannot be described by a single density distribution. We also find that the form of the inner spheroid density profile within distances of 2.5 kpc is closely matched by a power law with an index of -3.15 +/- 0.3.

  16. To High Luminosity and beyond!

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    This week marks a major milestone for the High Luminosity LHC (HL-LHC - see here) project, as it moves from the design study to the machine construction phase. HL-LHC will extend the LHC’s discovery potential, increasing luminosity by a factor of 10 beyond the original design value and allowing the scientific community to study new phenomena.    Composer Domenico Vicinanza (left) directs the musical performance of sonified LHC data during a special Hi-Lumi event (see box). The green light was given during the 5th Joint HiLumi LHC-LARP annual meeting that took place at CERN from 26 to 30 October 2015. The meeting saw the participation of more than 230 experts from all over the world to discuss the results and achievements of the HiLumi LHC Design Study. During the week, these experts approved the first version of the HL-LHC Technical Design Report – the document that, following the Preliminary Design Report issued in 2014, describes in detail how the LHC upgrade progra...

  17. Calibrating the Cepheid Period-Luminosity relation from the infrared surface brightness technique I. The p-factor, the Milky Way relations, and a universal K-band relation

    CERN Document Server

    Storm, J; Fouque, P; Barnes, T G; Pietrzynski, G; Nardetto, N; Weber, M; Granzer, T; Strassmeier, K

    2011-01-01

    We determine Period-Luminosity relations for Milky Way Cepheids in the optical and near-IR bands. These relations can be used directly as reference for extra-galactic distance determination to Cepheid populations with solar metallicity, and they form the basis for a direct comparison with relations obtained in exactly the same manner for stars in the Magellanic Clouds, presented in an accompanying paper. In that paper we show that the metallicity effect is very small and consistent with a null effect, particularly in the near-IR bands, and we combine here all 111 Cepheids from the Milky Way, the LMC and SMC to form a best relation. We employ the near-IR surface brightness (IRSB) method to determine direct distances to the individual Cepheids after we have recalibrated the projection factor using the recent parallax measurements to ten Galactic Cepheids and the constraint that Cepheid distances to the LMC should be independent of pulsation period. We confirm our earlier finding that the projection factor for c...

  18. Luminosity measurement at ILC

    CERN Document Server

    Bozovic Jelisavcic, I; Milutinovic Dumbelovic, G; Pandurovic, M; Smiljanic,I

    2013-01-01

    In this paper we describe a method of luminosity measurement at the future linear collider ILC that estimates and corrects for the impact of the dominant sources of systematic uncertainty originating from the beam-induced effects and the background from physics processes. Based on the relativistic kinematics of the collision frame of the Bhabha process, the beam-beam related uncertainty is reduced to a permille independently of the precision with which the beam parameters are known. With the specific event selection, different from the isolation cuts based on topology of the signal used at LEP, combined with the corrective methods we introduce, the overall systematic uncertainty in the peak region above 80% of the nominal center-of-mass energy meets the physics requirements to be at the few permille level at all ILC energies.

  19. Luminosity measurement at ILC

    Science.gov (United States)

    Božovi? Jelisav?i?, I.; Luki?, S.; Milutinovi? Dumbelovi?, G.; Pandurovi?, M.; Smiljani?, I.

    2013-08-01

    In this paper we describe a method of luminosity measurement at the future linear collider ILC that estimates and corrects for the impact of the dominant sources of systematic uncertainty originating from the beam-induced effects and the background from physics processes. Based on the relativistic kinematics of the collision frame of the Bhabha process, the beam-beam related uncertainty is reduced to a permille independently of the precision with which the beam parameters are known. With the specific event selection, different from the isolation cuts based on topology of the signal used at LEP, combined with the corrective methods we introduce, the overall systematic uncertainty in the peak region above 80% of the nominal center-of-mass energy meets the physics requirements to be at the few permille level at all ILC energies.

  20. Different Luminosity Correlation of GRBs

    Indian Academy of Sciences (India)

    Z. B. Zhang; H. C. Liu; L. Y. Jiang; D. Y. Chen

    2014-09-01

    We report our recent understanding about a tight correlation between relative spectral lag and luminosity (or redshift) for -ray bursts. The latest investigations indicate that the empirical correlations got from BATSE bursts also exist for Swift/BAT ones. The special luminosity-lag correlation is much similar to that of the luminosity with pulse number proposed by Schaefer (2003), but largely different from most others ever discovered. Note that our newly built luminosity-lag correlation predicts that luminosity should evolve with cosmological redshift as $L_{\\text{p}} \\propto (1 + z)^{2.4\\pm 0.7}$ that is excellently confirmed by Salvaterra et al. (2012) and Geng & Huang (2013). In addition, it is also surprisingly found that the luminosity-lag correlation can account for both long and short Swift/BAT bursts, which might be an evidence of the same radiation mechanism for diverse burst groups.

  1. The stars of low luminosity

    Science.gov (United States)

    Luyten, Willem J.

    A summary is presented of a search for stars of low luminosity, defined as objects of a luminosity smaller than one thousandth of that of the sun, bolometrically. It is shown that the most efficient way of finding such stars is through proper motion surveys which have resulted in the publication of catalogues containing data for some 4,000 such objects. The possibility is suggested that blue or white degenerates of much lower luminosity than the typical objects now known may exist.

  2. Luminosity determination at proton colliders

    Science.gov (United States)

    Grafström, P.; Kozanecki, W.

    2015-03-01

    Luminosity is a key parameter in any particle collider, and its precise determination has proven particularly challenging at hadron colliders. After introducing the concept of luminosity in its multiple incarnations and offering a brief survey of the pp and p p bar colliders built to date, this article outlines the various methods that have been developed for relative-luminosity monitoring, as well as the complementary approaches considered for establishing an absolute luminosity scale. This is followed by a survey, from both a historical and a technical perspective, of luminosity determination at the ISR, the S p p ¯ S, the Tevatron, RHIC and the LHC. For each of these, we first delineate the interplay between the experimental context, the specificities of the accelerator, and the precision targets suggested by the physics program. We then detail how the different methods were applied to specific experimental environments and how successfully they meet the precision goals.

  3. Recent luminosity improvements at the SLC

    International Nuclear Information System (INIS)

    The luminosity of the SLAC Linear Collider (SLC) has been increased by more than a factor of three during the 1997--98 run. Improved alignment and emittance tuning techniques throughout the accelerator resulted in minimal emittance growth from the damping rings to the final focus. In particular, a revised strategy for wakefield cancellation using precision beam size measurements at the entrance of the final focus proved effective for optimizing emittance. The final focus lattice was modified to provide stronger demagnification near the interaction point and to remove residual higher-order aberrations. Beam sizes as small as 1.5 by 0.65 microns were achieved at full beam intensity of 4 1010 particles per pulse. With these parameters, the mutual focusing of the beams in collision becomes significant, resulting in a further increase in the luminosity. Recorded SLD event rates confirmed the theoretical calculations of the disruption enhancement which was typically 50 to 100%

  4. Recent luminosity improvements at the SLC

    Energy Technology Data Exchange (ETDEWEB)

    Raimondi, P.; Usher, T.; Akre, R. [and others

    1998-07-01

    The luminosity of the SLAC Linear Collider (SLC) has been increased by more than a factor of three during the 1997--98 run. Improved alignment and emittance tuning techniques throughout the accelerator resulted in minimal emittance growth from the damping rings to the final focus. In particular, a revised strategy for wakefield cancellation using precision beam size measurements at the entrance of the final focus proved effective for optimizing emittance. The final focus lattice was modified to provide stronger demagnification near the interaction point and to remove residual higher-order aberrations. Beam sizes as small as 1.5 by 0.65 microns were achieved at full beam intensity of 4 10{sup 10} particles per pulse. With these parameters, the mutual focusing of the beams in collision becomes significant, resulting in a further increase in the luminosity. Recorded SLD event rates confirmed the theoretical calculations of the disruption enhancement which was typically 50 to 100%.

  5. Low-Luminosity Seyfert Nuclei

    CERN Document Server

    Ho, L C; Sargent, W L W; Ho, Luis C.; Filippenko, Alexei V.; Sargent, Wallace L. W.

    1996-01-01

    We describe a new sample of Seyfert nuclei discovered during the course of an optical spectroscopic survey of nearby galaxies. The majority of the objects, many recognized for the first time, have luminosities much lower than those of classical Seyferts and populate the faint end of the AGN luminosity function. A significant fraction of the nuclei emit broad H-alpha emission qualitatively similar to the broad lines seen in classical Seyfert 1 nuclei and QSOs.

  6. The CMS Pixel Luminosity Telescope

    CERN Document Server

    Kornmayer, Andreas

    2015-01-01

    The Pixel Luminosity Telescope is a new complement to the CMS detector for the LHC Run II data taking period. It consists of eight 3-layer telescopes based on silicon pixel detectors that are placed around the beam pipe on each end of CMS viewing the interaction point at small angle. A fast 3-fold coincidence of the pixel planes in each telescope will provide a bunch-by-bunch measurement of the luminosity. Particle tracking allows collision products to be distinguished from beam background, provides a self-alignment of the detectors, and a continuous in-time monitoring of the efficiency of each telescope plane. The PLT is an independent luminometer, essential to enhance the robustness on the measurement of the delivered luminosity and to reduce its systematic uncertainties. This will allow to determine production cross sections, and hence couplings, with higher precision and to set more stringent limits on new particle production.

  7. Mid-infrared luminosity as an indicator of the total infrared luminosity of galaxies

    CERN Document Server

    Takeuchi, T T; Iglesias-Páramo, J; Boselli, A; Burgarella, D

    2004-01-01

    The infrared (IR) emission plays a crucial role for understanding the star formation in galaxies hidden by dust. We first examined four estimators of the IR luminosity of galaxies, L_fir (Helou et al. 1988), L_tir (Dale et al. 2001), revised version of L_tir (Dale & Helou 2002) (we denote L_tir2), and L_ir (Sanders & Mirabel 1996) by using the observed SEDs of well-known galaxies. We found that L_ir provides excellent estimates of the total IR luminosity for a variety of galaxy SEDs. The performance of L_tir2 was also found to be very good. Using L_ir, we then statistically analyzed the IRAS PSCz galaxy sample (Saunders et al. 2000) and found useful formulae relating the MIR monochromatic luminosities [L(12um) and L(25um)], and L_ir. For this purpose we constructed a subsample of 1420 galaxies with all IRAS four band (12, 25, 60, and 100um) flux densities. We found linear relations between L_ir and MIR luminosities, L(12um) and L(25um). The prediction error with 95-% confidence level is a factor of 4-...

  8. Luminosity-time and luminosity-luminosity correlations for GRB prompt and afterglow plateau emissions

    Science.gov (United States)

    Dainotti, M.; Petrosian, V.; Willingale, R.; O'Brien, P.; Ostrowski, M.; Nagataki, S.

    2015-08-01

    We present an analysis of 123 gamma-ray bursts (GRBs) with known redshifts possessing an afterglow plateau phase. We reveal that L_a-T^{*}_a correlation between the X-ray luminosity La at the end of the plateau phase and the plateau duration, T^*_a, in the GRB rest frame has a power-law slope different, within more than 2?, from the slope of the prompt Lf-T^{*}f correlation between the isotropic pulse peak luminosity, Lf, and the pulse duration, T^{*}f, from the time since the GRB ejection. Analogously, we show differences between the prompt and plateau phases in the energy duration distributions with the afterglow emitted energy being on average 10 per cent of the prompt emission. Moreover, the distribution of prompt pulse versus afterglow spectral indexes does not show any correlation. In the further analysis we demonstrate that the Lpeak-La distribution, where Lpeak is the peak luminosity from the start of the burst, is characterized with a considerably higher Spearman correlation coefficient, ? = 0.79, than the one involving the averaged prompt luminosity, Lprompt-La, for the same GRB sample, yielding ? = 0.60. Since some of this correlation could result from the redshift dependences of the luminosities, namely from their cosmological evolution we use the Efron-Petrosian method to reveal the intrinsic nature of this correlation. We find that a substantial part of the correlation is intrinsic. We apply a partial correlation coefficient to the new de-evolved luminosities showing that the intrinsic correlation exists.

  9. Precision luminosity measurements at LHCb

    CERN Document Server

    Aaij, Roel; Adinolfi, Marco; Affolder, Anthony; Ajaltouni, Ziad; Akar, Simon; Albrecht, Johannes; Alessio, Federico; Alexander, Michael; Ali, Suvayu; Alkhazov, Georgy; Alvarez Cartelle, Paula; Alves Jr, Antonio Augusto; Amato, Sandra; Amerio, Silvia; Amhis, Yasmine; An, Liupan; Anderlini, Lucio; Anderson, Jonathan; Andreassen, Rolf; Andreotti, Mirco; Andrews, Jason; Appleby, Robert; Aquines Gutierrez, Osvaldo; Archilli, Flavio; Artamonov, Alexander; Artuso, Marina; Aslanides, Elie; Auriemma, Giulio; Baalouch, Marouen; Bachmann, Sebastian; Back, John; Badalov, Alexey; Baesso, Clarissa; Baldini, Wander; Barlow, Roger; Barschel, Colin; Barsuk, Sergey; Barter, William; Batozskaya, Varvara; Battista, Vincenzo; Bay, Aurelio; Beaucourt, Leo; Beddow, John; Bedeschi, Franco; Bediaga, Ignacio; Belogurov, Sergey; Belous, Konstantin; Belyaev, Ivan; Ben-Haim, Eli; Bencivenni, Giovanni; Benson, Sean; Benton, Jack; Berezhnoy, Alexander; Bernet, Roland; Bettler, Marc-Olivier; van Beuzekom, Martinus; Bien, Alexander; Bifani, Simone; Bird, Thomas; Bizzeti, Andrea; Bjørnstad, Pål Marius; Blake, Thomas; Blanc, Frédéric; Blouw, Johan; Blusk, Steven; Bocci, Valerio; Bondar, Alexander; Bondar, Nikolay; Bonivento, Walter; Borghi, Silvia; Borgia, Alessandra; Borsato, Martino; Bowcock, Themistocles; Bowen, Espen Eie; Bozzi, Concezio; Brambach, Tobias; Bressieux, Joël; Brett, David; Britsch, Markward; Britton, Thomas; Brodzicka, Jolanta; Brook, Nicholas; Brown, Henry; Bursche, Albert; Buytaert, Jan; Cadeddu, Sandro; Calabrese, Roberto; Calvi, Marta; Calvo Gomez, Miriam; Campana, Pierluigi; Campora Perez, Daniel; Carbone, Angelo; Carboni, Giovanni; Cardinale, Roberta; Cardini, Alessandro; Carson, Laurence; Carvalho Akiba, Kazuyoshi; Casse, Gianluigi; Cassina, Lorenzo; Castillo Garcia, Lucia; Cattaneo, Marco; Cauet, Christophe; Cenci, Riccardo; Charles, Matthew; Charpentier, Philippe; Chefdeville, Maximilien; Chen, Shanzhen; Cheung, Shu-Faye; Chiapolini, Nicola; Chrzaszcz, Marcin; Ciba, Krzystof; Cid Vidal, Xabier; Ciezarek, Gregory; Clarke, Peter; Clemencic, Marco; Cliff, Harry; Closier, Joel; Coco, Victor; Cogan, Julien; Cogneras, Eric; Cojocariu, Lucian; Collazuol, Gianmaria; Collins, Paula; Comerma-Montells, Albert; Contu, Andrea; Cook, Andrew; Coombes, Matthew; Coquereau, Samuel; Corti, Gloria; Corvo, Marco; Counts, Ian; Couturier, Benjamin; Cowan, Greig; Craik, Daniel Charles; Cruz Torres, Melissa Maria; Cunliffe, Samuel; Currie, Robert; D'Ambrosio, Carmelo; Dalseno, Jeremy; David, Pascal; David, Pieter; Davis, Adam; De Bruyn, Kristof; De Capua, Stefano; De Cian, Michel; De Miranda, Jussara; De Paula, Leandro; De Silva, Weeraddana; De Simone, Patrizia; Dean, Cameron Thomas; Decamp, Daniel; Deckenhoff, Mirko; Del Buono, Luigi; Déléage, Nicolas; Derkach, Denis; Deschamps, Olivier; Dettori, Francesco; Di Canto, Angelo; Dijkstra, Hans; Donleavy, Stephanie; Dordei, Francesca; Dorigo, Mirco; Dosil Suárez, Alvaro; Dossett, David; Dovbnya, Anatoliy; Dreimanis, Karlis; Dujany, Giulio; Dupertuis, Frederic; Durante, Paolo; Dzhelyadin, Rustem; Dziurda, Agnieszka; Dzyuba, Alexey; Easo, Sajan; Egede, Ulrik; Egorychev, Victor; Eidelman, Semen; Eisenhardt, Stephan; Eitschberger, Ulrich; Ekelhof, Robert; Eklund, Lars; El Rifai, Ibrahim; Elsasser, Christian; Ely, Scott; Esen, Sevda; Evans, Hannah Mary; Evans, Timothy; Falabella, Antonio; Färber, Christian; Farinelli, Chiara; Farley, Nathanael; Farry, Stephen; Fay, Robert; Ferguson, Dianne; Fernandez Albor, Victor; Ferreira Rodrigues, Fernando; Ferro-Luzzi, Massimiliano; Filippov, Sergey; Fiore, Marco; Fiorini, Massimiliano; Firlej, Miroslaw; Fitzpatrick, Conor; Fiutowski, Tomasz; Fol, Philip; Fontana, Marianna; Fontanelli, Flavio; Forty, Roger; Francisco, Oscar; Frank, Markus; Frei, Christoph; Frosini, Maddalena; Fu, Jinlin; Furfaro, Emiliano; Gallas Torreira, Abraham; Galli, Domenico; Gallorini, Stefano; Gambetta, Silvia; Gandelman, Miriam; Gandini, Paolo; Gao, Yuanning; García Pardiñas, Julián; Garofoli, Justin; Garra Tico, Jordi; Garrido, Lluis; Gascon, David; Gaspar, Clara; Gauld, Rhorry; Gavardi, Laura; Geraci, Angelo; Gersabeck, Evelina; Gersabeck, Marco; Gershon, Timothy; Ghez, Philippe; Gianelle, Alessio; Gianì, Sebastiana; Gibson, Valerie; Giubega, Lavinia-Helena; Gligorov, Vladimir; Göbel, Carla; Golubkov, Dmitry; Golutvin, Andrey; Gomes, Alvaro; Gotti, Claudio; Grabalosa Gándara, Marc; Graciani Diaz, Ricardo; Granado Cardoso, Luis Alberto; Graugés, Eugeni; Graziani, Giacomo; Grecu, Alexandru; Greening, Edward; Gregson, Sam; Griffith, Peter; Grillo, Lucia; Grünberg, Oliver

    2014-01-01

    Measuring cross-sections at the LHC requires the luminosity to be determined accurately at each centre-of-mass energy $\\sqrt{s}$. In this paper results are reported from the luminosity calibrations carried out at the LHC interaction point 8 with the LHCb detector for $\\sqrt{s}$ = 2.76, 7 and 8 TeV (proton-proton collisions) and for $\\sqrt{s_{NN}}$ = 5 TeV (proton-lead collisions). Both the "van der Meer scan" and "beam-gas imaging" luminosity calibration methods were employed. It is observed that the beam density profile cannot always be described by a function that is factorizable in the two transverse coordinates. The introduction of a two-dimensional description of the beams improves significantly the consistency of the results. For proton-proton interactions at $\\sqrt{s}$ = 8 TeV a relative precision of the luminosity calibration of 1.47% is obtained using van der Meer scans and 1.43% using beam-gas imaging, resulting in a combined precision of 1.12%. Applying the calibration to the full data set determin...

  10. Symmetric Moeller/Bhabha Luminosity Monitor

    International Nuclear Information System (INIS)

    Recent determinations of the proton electric to magnetic elastic form factor ratio from polarization transfer measurements at Jefferson Lab indicate an discrepancy with the elastic form factor ratio obtained using the Rosenbluth separation technique in unpolarized cross section measurements. This discrepancy has been explained as the effect of two-photon exchange in the calculation of the elastic electron-proton scattering cross section. The OLYMPUS experiment at DESY has been proposed to measure the ratio of positron-proton and electron-proton elastic scattering cross sections to quantify the effect of two-photon exchange to a percent level. In order to control the systematic uncertainties to the percent level the Symmetric Moeller/Bhabha Luminosity Monitor was proposed. The design and aspected performance will be presented.

  11. Luminosity Limitations at Hadron Colliders

    CERN Document Server

    Zimmermann, Frank

    2001-01-01

    I discuss fundamental luminosity limitations at hadron colliders, addressing head-on and long-range beam-beam interaction, empirical scaling, synchrotron radiation, intrabeam scattering, dynamic evolution during the store, flat beams, heat load, power consumption, and electron cloud. Parameters of past or operating colliders - ISR, SPS, Tevatron, RHIC -, are compared with the LHC and further extrapolated to an LHC upgrade and to the VLHC.

  12. Evolution of the luminosity function of quasars

    International Nuclear Information System (INIS)

    We show that the evolution of the luminosity of quasars cannot be excluded from the observational data. The observed evolution of the luminosity function may be interpreted as luminosity evolution as well as density evolution. Approximating the luminosity evolution by a single parameter exponential law, we show how to determine the evolution parameter by use of a limiting volume analysis. We apply the method to some useable complete samples and we present a brief discussion of the results. (orig.)

  13. Pinhole Luminosity Monitor with Feedback

    International Nuclear Information System (INIS)

    Previously, the generalized luminosity L was defined and calculated for all incident channels based on an NLC e+e- design. Alternatives were then considered to improve the differing beam-beam e-e- e? and ?? channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamsstrahlung that needs to be disposed of and whose flux depended on L. One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight-ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important--especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our ''pin-hole'' camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons

  14. Determination of the Absolute Luminosity at the LHC

    CERN Document Server

    White, Simon Mathieu; Puzo, P

    2010-01-01

    For particle colliders, the most important performance parameters are the beam energy and the luminosity. High energies allow the particle physics experiments to study and observe new effects. The luminosity describes the ability of the collider to produce the required number of useful interactions or events. It is defined as the proportionality factor between the event rate, measured by the experiments, and the cross section of the observed event which describes its probability to occur. The absolute knowledge of the luminosity therefore allows for the experiments to measure the absolute cross sections. The Large Hadron Collider (LHC) was designed to produce proton proton collisions at a center of mass energy of 14 TeV. This energy would be the highest ever reached in a particle accelerator. The knowledge and understanding of particle physics at such high energy is based on simulations and theoretical predictions. As opposed to e+ e- colliders, for which the Bhabba scattering cross section can be accurately ...

  15. Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

    CERN Document Server

    Norris, J P

    2002-01-01

    Spectral lags are deduced for 1437 long GRBs with peak fluxes extending to near the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the peak flux-lag plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self- consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations -- including a possible nearby subpopulation of low-luminosity, long-lag GRBs -- and for unified gamma-ray/afterglow scenarios which would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor.

  16. The low-luminosity stellar mass function

    International Nuclear Information System (INIS)

    The stellar mass function for low-mass stars is constrained using the stellar luminosity function and the slope of the mass-luminosity relation. We investigate the range of mass functions for stars with absolute visual magnitude fainter than MV ? +5 which are consistent with both the local luminosity function and the rather poorly determined mass-absolute visual magnitude relation. Points of inflexion in the mass-luminosity relation exist because of the effects of H-, H2 and of other molecules on the opacity and equation of state. The first two of these correspond to absolute magnitudes MV ? +7 and MV? +12, respectively, at which structure is evident in the stellar luminosity function (a flattening and a maximum, respectively). Combining the mass-luminosity relation which shows these inflexion points with a peaked luminosity function, we test smooth mass functions in the mass range 0.9-0.1 the solar mass. (author)

  17. Optimizing integrated luminosity of future hadron colliders

    CERN Document Server

    Benedikt, Michael; Zimmermann, Frank

    2015-01-01

    The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical “beam-beam limit”), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value...

  18. The Ultraviolet Luminosity Function of the Earliest Galaxies

    CERN Document Server

    O'Shea, Brian W; Xu, Hao; Norman, Michael L

    2015-01-01

    In this paper, we present the first results from the Renaissance Simulations, a suite of extremely high-resolution and physics-rich AMR calculations of high redshift galaxy formation performed on the Blue Waters supercomputer. These simulations contain hundreds of well-resolved galaxies at $z \\sim 25-8$, and make several novel, testable predictions. Most critically, we show that the ultraviolet luminosity function of our simulated galaxies is consistent with observations of high-z galaxy populations at the bright end of the luminosity function (M$_{1600} \\leq -17$), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations. This flattening of the luminosity function is due to two factors: (i) the strong dependence of the stellar fraction on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower stellar fractions and thus lower luminosities at a given halo virial mass; and (ii)...

  19. Ether, Luminosity and Galactic Source Counts

    Science.gov (United States)

    Tomaschitz, Roman

    1998-08-01

    An interpretation of the cosmological redshift in terms of a cosmic ether is given. We study a Robertson-Walker cosmology in which the ether is phenomenologically defined by a homogeneous and isotropic permeability tensor. The speed of light becomes so a function of cosmic time like in a dielectric medium. However, the cosmic ether is dispersion free, it does not lead to a broadening of spectral lines. Locally, in Euclidean frames, the scale factors of the permeability tensor get absorbed in the fundamental constants. Mass and charge scale with cosmic time, and so do atomic energy levels. This substantially changes the interpretation of the cosmological redshift as a Doppler shift. Photon frequencies are independent of the expansion factor; their time scaling is determined by the permeability tensor. The impact of the ether on the luminosity-distance, on the distance-redshift relation, and on galactic number counts is discussed. The Hubble constant is related to the scale factors of the metric and the permeability tensor. We study the effects of the ether at first in comoving Robertson-Walker coordinates, and then, in the context of a flat but expanding space- time, in the globally geodesic rest frames of galactic observers.

  20. Ether, Luminosity and Galactic Source Counts

    CERN Document Server

    Tomaschitz, R

    1998-01-01

    An interpretation of the cosmological redshift in terms of a cosmic ether is given. We study a Robertson-Walker cosmology in which the ether is phenomenologically defined by a homogeneous and isotropic permeability tensor. The speed of light becomes so a function of cosmic time like in a dielectric medium. However, the cosmic ether is dispersion free, it does not lead to a broadening of spectral lines. Locally, in Euclidean frames, the scale factors of the permeability tensor get absorbed in the fundamental constants. Mass and charge scale with cosmic time, and so do atomic energy levels. This substantially changes the interpretation of the cosmological redshift as a Doppler shift. Photon frequencies are independent of the expansion factor; their time scaling is determined by the permeability tensor. The impact of the ether on the luminosity-distance, on the distance-redshift relation, and on galactic number counts is discussed. The Hubble constant is related to the scale factors of the metric and the permeab...

  1. Factoring

    OpenAIRE

    Lenstra, Arjen K.

    1994-01-01

    Factoring, finding a non-trivial factorization of a composite positive integer, is believed to be a hard problem. How hard we think it is, however, changes almost on a daily basis. Predicting how hard factoring will be in the future, an important issue for cryptographic applications of composite numbers, is therefore a challenging task. The author presents a brief survey of general purpose integer factoring algorithms and their implementations

  2. Luminosity spectrum reconstruction at linear colliders

    Science.gov (United States)

    Poss, Stéphane; Sailer, André

    2014-04-01

    A good knowledge of the luminosity spectrum is mandatory for many measurements at future colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV compact linear collider. The model is used within a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5 % over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.

  3. Luminosity monitoring and calibration of BLM

    Science.gov (United States)

    Xue, Zhen; Xu, Zi-Zong; Wang, Xiao-Lian; Hu, Tao; Wang, Zhi-Yong; Fu, Cheng-Dong; Yan, Wen-Biao; Lü, Jun-Guang; Zhou, Li; Cai, Xiao; Yu, Bo-Xiang; Fang, Jian; Sun, Xi-Lei; Shi, Feng; Wang, Zhi-Gang; An, Zheng-Hua; Sun, Li-Jun; Liu, Hong-Bang; Zhang, Ai-Wu; Wang, Xiao-Dong

    2011-01-01

    The BEPCII Luminosity Monitor (BLM) monitors relative luminosity per bunch. The counting rates of gamma photons, which are proportional to the luminosities from the BLM at the center of mass system energy of the ? (3770) resonance, are obtained with a statistical error of 0.01% and a systematic error of 4.1%. Absolute luminosities are also determined by the BESIII End-cap Electro-Magnetic Calorimeter (EEMC) using Bhabha events with a statistical error of 2.3% and a systematic error of 3.5%. The calibration constant between the luminosities obtained with the EEMC and the counting rates of the BLM are found to be 0.84±0.03 (×1026 cm-2·count-1). With the calibration constant, the counting rates of the BLM can be scaled up to absolute luminosities.

  4. Luminosity Measurements with the ATLAS Detector

    CERN Document Server

    Maettig, Stefan; Pauly, T

    For almost all measurements performed at the Large Hadron Collider (LHC) one crucial ingredient is the precise knowledge about the integrated luminosity. The determination and precision on the integrated luminosity has direct implications on any cross-section measurement, and its instantaneous measurement gives important feedback on the conditions at the experimental insertions and on the accelerator performance. ATLAS is one of the main experiments at the LHC. In order to provide an accurate and reliable luminosity determination, ATLAS uses a variety of different sub-detectors and algorithms that measure the luminosity simultaneously. One of these sub-detectors are the Beam Condition Monitors (BCM) that were designed to protect the ATLAS detector from potentially dangerous beam losses. Due to its fast readout and very clean signals this diamond detector is providing in addition since May 2011 the official ATLAS luminosity. This thesis describes the calibration and performance of the BCM as a luminosity detec...

  5. Characterizing Luminosity Evolution in the Tevatron

    CERN Document Server

    McCrory, Elliott

    2005-01-01

    We derive an approximate form of a luminosity evolution in a high intensity hadron collider taking into account the most important phenomena of intrabeam scattering (IBS), beam burn-up due to luminosity and beam-beam effects. It is well known that an exponential decay does not describe luminosity evolution very well unless the lifetime is allowed to vary with time. However, a "1/time" evolution, which this derivation shows is a good approximation, fits data from the Tevatron well.

  6. Spatial and luminosity distributions of galactic satellites

    OpenAIRE

    Guo, Quan; Cole, Shaun; Eke, Vincent; Frenk, Carlos; Helly, John

    2013-01-01

    We investigate the luminosity functions (LFs) and projected number density profiles of galactic satellites around isolated primaries of different luminosities. We measure these quantities for model satellites placed into the Millennium and Millennium II dark matter simulations by the GALFORM semi-analytic galaxy formation model for different bins of primary galaxy magnitude and we investigate their dependence on satellite luminosity. We compare our model predictions to the d...

  7. Calibration of GRB Luminosity Relations with Cosmography

    OpenAIRE

    Gao, He; Liang, Nan; Zhu, Zong-Hong

    2010-01-01

    For the use of Gamma-Ray Bursts (GRBs) to probe cosmology in a cosmology-independent way, a new method has been proposed to obtain luminosity distances of GRBs by interpolating directly from the Hubble diagram of SNe Ia, and then calibrating GRB relations at high redshift. In this paper, following the basic assumption in the interpolation method that objects at the same redshift should have the same luminosity distance, we propose another approach to calibrate GRB luminosity...

  8. Construction of luminosity function for galaxy clusters

    Science.gov (United States)

    God?owski, W?odzimierz; Popiela, Joanna; Bajan, Katarzyna; Biernacka, Monika; Flin, Piotr; Panko, Elena

    2015-02-01

    The luminosity function is an important quantity for analysis of large scale structure statistics, interpretation of galaxy counts (Lin & Kirshner 1996). We investigate the luminosity function of galaxy clusters. This is performed by counting the brightness of galaxies belonging to clusters in PF Catalogue. The obtained luminosity function is significantly different than that obtained both for optical and radiogalaxies (Machalski & Godowski 2000). The implications of this result for theories of galaxy formation are discussed as well.

  9. The QSO variability-luminosity-redshift relation

    OpenAIRE

    Fernandes, R. Cid; I. Aretxaga; TERLEVICH, R

    1996-01-01

    The relationship between variability, luminosity and redshift in the South Galactic Pole QSO sample is examined in an effort to disentangle the effects of luminosity and redshift in the amplitude of the optical variations. The anticorrelation between variability and luminosity found by other authors is confirmed. Our analysis also supports claims that variability increases with redshift, most likely due to an anticorrelation between variability and wavelength. In particular,...

  10. Optimizing integrated luminosity of future hadron colliders

    Science.gov (United States)

    Benedikt, Michael; Schulte, Daniel; Zimmermann, Frank

    2015-10-01

    The integrated luminosity, a key figure of merit for any particle-physics collider, is closely linked to the peak luminosity and to the beam lifetime. The instantaneous peak luminosity of a collider is constrained by a number of boundary conditions, such as the available beam current, the maximum beam-beam tune shift with acceptable beam stability and reasonable luminosity lifetime (i.e., the empirical "beam-beam limit"), or the event pileup in the physics detectors. The beam lifetime at high-luminosity hadron colliders is largely determined by particle burn off in the collisions. In future highest-energy circular colliders synchrotron radiation provides a natural damping mechanism, which can be exploited for maximizing the integrated luminosity. In this article, we derive analytical expressions describing the optimized integrated luminosity, the corresponding optimum store length, and the time evolution of relevant beam parameters, without or with radiation damping, while respecting a fixed maximum value for the total beam-beam tune shift or for the event pileup in the detector. Our results are illustrated by examples for the proton-proton luminosity of the existing Large Hadron Collider (LHC) at its design parameters, of the High-Luminosity Large Hadron Collider (HL-LHC), and of the Future Circular Collider (FCC-hh).

  11. ISR Superconducting High-Luminosity (low beta ) insertion

    CERN Multimedia

    1981-01-01

    The photograph shows two of the 8 Superconducting Quadrupoles installed in ISR intersection I8 with their helium supply flexible lines,vacuum equipment,power and signal cables. The increase of luminosity produced by this insertion was above a factor 7. On the right one can see part of Open-Axial-Field Magnet. The person on the left side is Stephan Pichler. See also photo 7702690 and its abstract.

  12. Luminosity distance in GX cosmological models

    OpenAIRE

    Khachatryan, H G; Vereshchagin, G. V.; Yegorian, G

    2007-01-01

    We derive luminosity distance equation in Gurzadyan-Xue cosmological models and compared it with available supernovae and radio galaxies data sets. We found that the luminosity distance does not depend explicitly the speed of light and the gravitation constant, and depends only on the matter parameter (GX-invariant) and curvature.

  13. Symmetric Moeller/Bhabha luminosity monitor for the OLYMPUS experiment

    International Nuclear Information System (INIS)

    Recent determinations of the proton electric to magnetic form factor ratio indicate an unexpected discrepancy between the ratio obtained using polarisation transfer measurements and the ratio from the Rosenbluth separation technique in unpolarised cross section measurements. This discrepancy has been explained theoretically as the effect of two-photon exchange. The OLYMPUS experiment at DESY proposed to measure the ratio of positron-proton and electron-proton elastic scattering cross sections. The experiment utilised beams of electrons and positrons in the DORIS ring at 2.0 GeV incident on an unpolarized internal hydrogen gas target and the BLAST detector from the MIT-Bates Linear Accelerator Center with modest upgrades. In order to reduce the systematic error from the determination of luminosity, redundant measurements of the relative luminosity were necessary. The symmetric Moeller/Bhabha luminosity monitor built at the University of Mainz consisted of two symmetric arrays of lead fluoride (PbF2) crystals. Results on the performance of the symmetric Moeller/Bhabha luminosity monitor are presented in this contribution.

  14. The Online Luminosity Calculator of ATLAS

    CERN Document Server

    Maettig, S; The ATLAS collaboration

    2010-01-01

    Online luminosity monitoring at the LHC is important for optimizing the luminosity at the experimental insertions and vital for good data taking of the LHC experiments. It is an important diagnostic tool, in particular for the normalization of trigger rates and data samples. The ATLAS experiment has several sub-detectors, which can be used for relative luminosity measurements. In order to collect all data from the variety of different sources and to process them centrally, the software application “Online Luminosity Calculator” has been developed. It is written in C++ and integrated into the ATLAS online software framework. There are three main tasks of this application: first, collection of data from the sub-detectors and the LHC beam instrumentation. This requires handling of online information published in various formats, using different middleware. Further, calibration of the raw luminosity information, time integration and normalization. The last step is the publication of the results in a coherent ...

  15. THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    McGreer, Ian D.; Fan Xiaohui [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721-0065 (United States); Jiang Linhua [School of Earth and Space Exploration, Arizona State University, Tempe, AZ 85287 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Ross, Nicholas P.; White, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); Shen Yue [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Schneider, Donald P.; Brandt, W. Niel [Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); DeGraf, Colin [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Ge Jian [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL 32611 (United States); Streblyanska, Alina, E-mail: imcgreer@as.arizona.edu [Instituto de Astrofisica de Canarias (IAC), E-38200 La Laguna, Tenerife (Spain)

    2013-05-10

    We present a measurement of the Type I quasar luminosity function at z = 5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M{sub 1450} < -26) with Sloan Digital Sky Survey (SDSS) data covering {approx}6000 deg{sup 2}, then extend to lower luminosities (M{sub 1450} < -24) with newly discovered, faint z {approx} 5 quasars selected from 235 deg{sup 2} of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey, and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7 < z < 5.1 quasars that is highly complete, with 73 spectroscopic identifications out of 92 candidates. Our color selection method is also highly efficient: of the 73 spectra obtained, 71 are high-redshift quasars. These observations reach below the break in the luminosity function (M{sub 1450}{sup *}{approx}-27). The bright-end slope is steep ({beta} {approx}< -4), with a constraint of {beta} < -3.1 at 95% confidence. The break luminosity appears to evolve strongly at high redshift, providing an explanation for the flattening of the bright-end slope reported previously. We find a factor of {approx}2 greater decrease in the number density of luminous quasars (M{sub 1450} < -26) from z = 5 to z = 6 than from z = 4 to z = 5, suggesting a more rapid decline in quasar activity at high redshift than found in previous surveys. Our model for the quasar luminosity function predicts that quasars generate {approx}30% of the ionizing photons required to keep hydrogen in the universe ionized at z = 5.

  16. Luminosity determination at HERA-B

    CERN Document Server

    Abt, I; Agari, M; Albrecht, H; Aleksandrov, A; Amaral, V S; Amorim, A; Aplin, S J; Aushev, V; Bagaturia, Yu S; Balagura, V; Bargiotti, M; Barsukova, O; Bastos, J; Batista, J; Bauer, C; Bauer, T S; Belkov, A; Belkov, Ar; Belotelov, I; Bertin, A; Bobchenko, B; Böcker, M; Bogatyrev, A; Böhm, G; Brauer, M; Bruinsma, M; Bruschi, M; Buchholz, P; Buran, T; Carvalho, J; Conde, P; Cruse, C; Dam, M; Danielsen, K M; Danilov, M; De Castro, S; Deppe, H; Dong, X; Dreis, H B; Egorytchev, V; Ehret, K; Eisele, F; Emeliyanov, D; Essenov, S; Fabbri, L; Faccioli, P; Feuerstack-Raible, M; Flammer, J; Fominykh, B; Funcke, M; Garrido, L; Gellrich, A; Giacobbe, B; Glass, J; Goloubkov, D; Golubkov, Y; Golutvin, A; Golutvin, I A; Gorbounov, I; Gorisek, A; Gouchtchine, O; Goulart, D C; Gradl, S; Gradl, W; Grimaldi, F; Groth-Jensen, J; Guilitsky, Yu; Hansen, J D; Hernández, J M; Hofmann, W; Hohlmann, M; Hott, T; Hulsbergen, W; Husemann, U; Igonkina, O; Ispiryan, M; Jagla, T; Jiang, C; Kapitza, H; Karabekyan, S; Karpenko, N; Keller, S; Kessler, J; Khasanov, F; Kiryushin, Yu T; Kisel, I; Klinkby, E; Knöpfle, K T; Kolanoski, H; Korpar, S; Krauss, C; Kreuzer, P; Krizan, P; Krücker, D; Kupper, S; Kvaratskheliia, T; Lanyov, A; Lau, K; Lewendel, B; Lohse, T; Lomonosov, B; Männer, R; Mankel, R; Masciocchi, S; Massa, I; Matchikhilian, I; Medin, G; Medinnis, M; Mevius, M; Michetti, A; Mikhailov, Yu; Mizuk, R; Muresan, R; Zur Nedden, M; Negodaev, M; Nörenberg, M; Nowak, S; Núñez-Pardo de Vera, M T; Ouchrif, M; Ould-Saada, F; Padilla, C; Peralta, D; Pernack, R; Pestotnik, R; Petersen, B AA; Piccinini, M; Pleier, M A; Poli, M; Popov, V; Pose, D; Prystupa, S; Pugatch, V; Pylypchenko, Y; Pyrlik, J; Reeves, K; Ressing, D; Rick, H; Riu, I; Robmann, P; Rostovtseva, I; Rybnikov, V; Sánchez, F; Sbrizzi, A; Schmelling, M; Schmidt, B; Schreiner, A; Schröder, H; Schwanke, U; Schwartz, A J; Schwarz, A S; Schwenninger, B; Schwingenheuer, B; Sciacca, F; Semprini-Cesari, N; Shuvalov, S; Silva, L; Sozuer, L; Solunin, S; Somov, A; Somov, S; Spengler, J; Spighi, R; Spiridonov, A; Stanovnik, A; Staric, M; Stegmann, C; Subramanian, H S; Symalla, M; Tikhomirov, I; Titov, M; Tsakov, I; Uwer, U; Van Eldik, C; Vasilev, Yu; Villa, M; Vitale, A; Vukotic, I; Wahlberg, H; Walenta, A H; Walter, M; Wang, J J; Wegener, D; Werthenbach, U; Wolters, H; Wurth, R; Wurz, A; Xella, S M; Zaitsev, Yu; Zavertyaev, M; Zeuner, T; Zhelezov, A; Zheng, Z; Zimmermann, R; Zivko, T; Zoccoli, A

    2007-01-01

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of delta-rays generated in the target and comment on the possible use of such delta rays to measure luminosity.

  17. On the red-giant luminosity bump

    CERN Document Server

    Christensen-Dalsgaard, J

    2015-01-01

    The increase in luminosity as a star evolves on the red-giant branch is interrupted briefly when the hydrogen-burning shell reaches the vicinity of the composition discontinuity left behind from the first convective dredge-up. The non-monotonic variation of luminosity causes an accumulation of stars, known as the `bump', in the distribution of stars in the colour-magnitude diagrams of stellar clusters, which has substantial diagnostic potential. Here I present numerical results on this behaviour and discuss the physical reason for the luminosity variation, with the goal of strengthening the understanding of origin of the phenomenon and hence of its diagnostic potential.

  18. A fast luminosity monitor for BEPCII

    Science.gov (United States)

    Xue, Zhen; Shan, Qing; Xu, Zi-Zong; Wang, Xiao-Lian; Wu, Jian; Wang, Yong-Gang; Zhang, Tao; Hu, Tao; Cai, Xiao; Wang, Yi-Fang

    2010-04-01

    The fast luminosity monitor counting the ? photons above a given energy threshold emitted from radiative Bhabha scattering has been operated in the BEPCII to measure the relative luminosity bunch by bunch for the first time and used successfully in beam tuning of BEPCII. In the relative mode the monitor is able to deliver the relative luminosities with an accuracy of 0.8%. By steering the electron beam while observing the counting rate changes of the monitor the horizontal and vertical sizes of the bunch spots can be estimated as: sxe+ = sxe- = 0.356 mm, sye+ = sye- = 0.011 mm.

  19. Luminosity determination at HERA-B

    Energy Technology Data Exchange (ETDEWEB)

    Abt, I. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Adams, M. [Dortmund Univ. (Germany). Inst. fuer Physik; Agari, M. [Max-Planck-Institut fuer Kernphysik, Heidelberg (DE)] (and others)

    2007-05-15

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of {delta}-rays generated in the target and comment on the possible use of such delta rays to measure luminosity. (orig.)

  20. The X-ray luminosity functions of Abell clusters from the Einstein Cluster Survey

    Science.gov (United States)

    Burg, R.; Giacconi, R.; Forman, W.; Jones, C.

    1994-01-01

    We have derived the present epoch X-ray luminosity function of northern Abell clusters using luminosities from the Einstein Cluster Survey. The sample is sufficiently large that we can determine the luminosity function for each richness class separately with sufficient precision to study and compare the different luminosity functions. We find that, within each richness class, the range of X-ray luminosity is quite large and spans nearly a factor of 25. Characterizing the luminosity function for each richness class with a Schechter function, we find that the characteristic X-ray luminosity, L(sub *), scales with richness class as (L(sub *) varies as N(sub*)(exp gamma), where N(sub *) is the corrected, mean number of galaxies in a richness class, and the best-fitting exponent is gamma = 1.3 +/- 0.4. Finally, our analysis suggests that there is a lower limit to the X-ray luminosity of clusters which is determined by the integrated emission of the cluster member galaxies, and this also scales with richness class. The present sample forms a baseline for testing cosmological evolution of Abell-like clusters when an appropriate high-redshift cluster sample becomes available.

  1. Hipparcos period-luminosity relations for Miras and semiregular variables

    CERN Document Server

    Bedding, T R

    1998-01-01

    We present period-luminosity diagrams for nearby Miras and semiregulars, selecting stars with parallaxes better than 20 per cent and well-determined periods. Using K-band magnitudes, we find two well-defined P-L sequences, one corresponding to the standard Mira P-L relation and the second shifted to shorter periods by a factor of about 1.9. The second sequence only contains semiregular variables, while the Mira sequence contains both Miras and semiregulars. Several semiregular stars show double periods in agreement with both relations. The Whitelock evolutionary track is shown to fit the data, indicating that the semiregulars are Mira progenitors. The transition between the two sequences may correspond to a change in pulsation mode or to a change in the stellar structure. Large amplitude pulsations leading to classical Mira classification occur mainly near the tip of the local AGB luminosity function.

  2. Symmetric Moeller/Bhabha luminosity monitor for the OLYMPUS experiment

    International Nuclear Information System (INIS)

    The OLYMPUS experiment ran on the DORIS storage ring at DESY, Hamburg to measure the elastic cross sections for both positron and electron scattering from hydrogen to quantify the two-photon contribution to elastic ep scattering. Two-photon exchange is widely considered to be responsible for the the discrepancy in the proton form factor ratio determined using the Rosenbluth technique and polarization transfer. The experiment alternated daily between positron and electron beams at 2.01 GeV incident on an unpolarized, internal, hydrogen gas target. The luminosity delivered to the experiment was monitored by a redundant set of detectors: a high precision, symmetric Moeller/Bhabha calorimeter and a tracking telescope at 12 degrees. The symmetric Moeller/Bhabha calorimeter was built at Mainz and consisted of two symmetric arrays of lead fluoride crystals. Results on the performance of the SYMB luminosity monitor will be presented together with an overview of the OLYMPUS experiment.

  3. The Luminosity Function of Cluster Galaxies. III

    OpenAIRE

    Parolin, I.; Molinari, E.; Chincarini, G.

    2003-01-01

    We investigated the optical properties of 7 clusters of galaxies observed in three colors over the range of absolute magnitudes -24 < M < -12. Our aim is to estimate the Luminosity Function and the total cluster luminosity of our sample in order to have information about the formation and the evolution of galaxies in clusters. In this paper, we present the main points of our analysis and give the formal parameters obtained by fitting the data using the maximum likelihood alg...

  4. Luminosity determination at HERA-B

    OpenAIRE

    Abt, I.; DESY Forschung Hochenergiephysik; Aleksandrov, A; S.J. Aplin; Aushev, V.; Bagaturia, Y.; Bargiotti, M.; Belotelov, I.; Bertin, A.(INFN Sezione di Bologna; Dipartimento di Fisica, Università di Bologna, Bologna, Italy); Bobchenko, B.; A. Bogatyrev; Bruinsma, M.(University of California at Irvine, 92697, Irvine, California, USA); Buchholz, P; C. Cruse; M. Dam

    2007-01-01

    A detailed description of an original method used to measure the luminosity accumulated by the HERA-B experiment for a data sample taken during the 2002-2003 HERA running period is reported. We show that, with this method, a total luminosity measurement can be achieved with a typical precision, including overall systematic uncertainties, at a level of 5% or better. We also report evidence for the detection of delta-rays generated in the target and comment on the possible use...

  5. High rate luminosity monitors for CESR*

    International Nuclear Information System (INIS)

    Compact luminosity monitors using Bismuth Germanate (BGO) crystals with photodiode readout have been built and installed at the Cornell Electron Storage Ring. The counters are located 2.0 m from the interaction point, outside the inner pair of quadrupoles which are horizontally defocussing. They observe Bhabha scatters near the horizontal plane with angles between 10 and and 16 milliradians. Real coincidence rates are several hundred Hertz at 2x10/sup 31/cm/sup -2/s/sup -1/ luminosity and accidentals are reliably subtracted using a delayed coincidence technique. The Cornell Electron Storage Ring (CESR) is an e/sup +/e/sup -/ storage ring used primarily for the study of e/sup +/e/sup -/ collisions in the ? energy region (E/sub beam/ ? 5 GeV). With the recent addition of permanent rare earth cobalt (REC) magnet microbeta quadrupoles to the two CESR interaction regions, the angular region traditionally covered by a small angle luminosity monitor was made inaccessible as the microbeta quadrupoles have their front face only 55 cm from the interaction point. At the same time the CESR machine group made clear the need for a ''luminosity signal'' with a time constant appropriate for tuning, i.e. a few seconds. For example, the old CLEO detector luminosity monitor ran at scaler rates of 13 Hz at a luminosity of 10/sup 31/cm/sup -2/s/sup -1/, which implies a one minute counting time to get a statistically significant measurement

  6. Luminosities for Vector-Boson Vector-Boson Scattering at High Energy Colliders

    OpenAIRE

    Kuss, I.; Spiesberger, H.

    1995-01-01

    We derive exact expressions for luminosities of massive vector-boson pairs which can be used to describe the cross sections for processes in hadron collisions or $e^+e^-$ annihilation which proceed via two-vector-boson scattering. Our approach correctly takes into account the mutual influence of the emission of one vector boson on the emission of a second one. We show that only approximately the exact luminosities can be factorized into convolutions of single-vector-boson di...

  7. The Environmental Dependence of the Luminosity-Size Relation for Galaxies

    Science.gov (United States)

    Nair, Preethi B.; van den Bergh, Sidney; Abraham, Roberto G.

    2010-05-01

    We have examined the luminosity-size relationship as a function of environment for 12,150 Sloan Digital Sky Survey galaxies with precise visual classifications from the catalog of Nair & Abraham. Our analysis is subdivided into investigations of early-type galaxies and late-type galaxies. Early-type galaxies reveal a surprisingly tight luminosity-size relation. The dispersion in luminosity about the fiducial relation is only ~0.14 dex (0.35 mag), even though the sample contains galaxies that differ by a factor of almost 100 in luminosity. The dispersion about the luminosity-size relation is comparable to the dispersion about the fundamental plane, even though the luminosity-size relation is fundamentally simpler and computed using purely photometric parameters. We attribute this to using a clean sample of elliptical galaxies and a large Petrosian size measure, implying that the fundamental plane may closely resemble a fundamental line, provided a different (and arguably better) size measurement is adopted. The key contributors to the dispersion about the luminosity-size relation are found to be color and central concentration expanding our analysis to the full range of morphological types, we show that the slope, zero point, and scatter about the luminosity-size relation are independent of environmental density. Our study thus indicates that whatever process is building galaxies is doing so in a way that preserves fundamental scaling laws even as the typical luminosity of galaxies changes with environment. However, the distribution of galaxies along the luminosity-size relation is found to be strongly dependent on galaxy environment. This variation is in the sense that, at a given morphology, larger and more luminous galaxies are rarer in sparser environments. Our analysis of late-type galaxy morphologies reveals that scatter increases toward later Hubble types. Taken together, these results place strong constraints on conventional hierarchical models in which galaxies are built up in an essentially stochastic way.

  8. Dependence of Fanaroff-Riley break of radio galaxies on luminosity and redshift

    Science.gov (United States)

    Singal, Ashok K.; Rajpurohit, Kamlesh

    2014-09-01

    We investigate the dependence of the Fanaroff-Riley (FR) 1/2 dichotomy of radio galaxies on their luminosities and redshifts. Because of a very strong redshift-luminosity correlation (Malmquist bias) in a flux-limited sample, any redshift-dependent effect could appear as a luminosity-related effect and vice versa. A question could then arise—do all the morphological differences seen in the two classes (FR 1 and 2 types) of sources, usually attributed to the differences in their luminosities, could as well be primarily a redshift-dependent effect? A sharp break in luminosity, seen among the two classes, could after all reflect a sharp redshift dependence due to a rather critical ambient density value at some cosmic epoch. A doubt on these lines does not seem to have been raised in past and things have never been examined with this particular aspect in mind. We want to ascertain the customary prevalent view in the literature that the systematic differences in the two broad morphology types of FR 1 and 2 radio galaxies are indeed due to the differences in their luminosities, and not due to a change in redshift. Here we investigate the dependence of FR 1/2 dichotomy of radio galaxies on luminosity and redshift by using the 3CR sample, where the FR 1/2 dichotomy was first seen, supplemented by data from an additional sample (MRC), that goes about a factor of 5 or more deeper in flux-density than the original 3CR sample. This lets us compare sources with similar luminosities but at different redshifts as well as examine sources at similar redshifts but with different luminosities, thereby allowing us a successful separation of the otherwise two intricately entangled effects. We find that the morphology type is not directly related to redshift and the break between the two types of morphologies seems to depend only upon the radio luminosity.

  9. High-Luminosity LHC moves to the next phase

    CERN Multimedia

    2015-01-01

    This week saw several meetings vital for the medium-term future of CERN.    From Monday to Wednesday, the Resource Review Board, RRB, that oversees resource allocation in the LHC experiments, had a series of meetings. Thursday then saw the close-out meeting for the Hi-Lumi LHC design study, which was partially funded by the European Commission. These meetings focused on the High Luminosity upgrade for the LHC, which responds to the top priority of the European Strategy for Particle Physics adopted by the CERN Council in 2013. This upgrade will transform the LHC into a facility for precision studies, the logical next step for the high-energy frontier of particle physics. It is a challenging upgrade, both for the LHC and the detectors. The LHC is already the highest luminosity hadron collider ever constructed, generating up to a billion collisions per second at the heart of the detectors. The High Luminosity upgrade will see that number rise by a factor of five from 2025. For the detectors...

  10. EU supports the LHC high-luminosity study

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The design collision energy and luminosity of the LHC are already at record numbers, making the machine one of the most complex scientific instruments ever built. However, to extend its discovery potential even further, a major upgrade of the LHC will be required around 2020. This will increase its average luminosity by a factor of 5 to 10 beyond its design value. Fifteen worldwide institutions and the European Union are supporting the initial design phase of the project through the HiLumi LHC programme, whose kick-off meeting will take place on 16-18 November.   The CERN team that has successfully built and tested the Short Magnet Coil – a small 40 cm long magnet capable of producing a 12.5 T magnetic field. The upgrade of the LHC will require about 10 years of design, construction and implementation. The new machine configuration will be called “High Luminosity LHC” (HL-LHC). The similarly named “HiLumi LHC” is the EU programme that supports...

  11. Luminosity monitoring at OLYMPUS with forward-angle elastic scattering

    Science.gov (United States)

    Ates, Ozgur; Olympus Collaboration

    2013-10-01

    The OLYMPUS experiment at DESY has taken data during two periods in 2012 to measure the ratio of positron-proton and electron-proton elastic scattering cross sections. The goal of OLYMPUS is to quantify the effect of two-photon exchange, which is widely considered to be responsible for the discrepancy between measurements of the proton electric to magnetic form factor ratio with the Rosenbluth separation and polarization transfer methods. In order to control the systematic uncertainties to the sub-percent level, the luminosities have been monitored redundantly and with high precision by measuring the rates for symmetric Moller and Bhabha scattering, and by measuring the ep-elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) and MWPC (Multi Wire Proportional Chamber) technology. Based on the data analysis of GEM and MWPC luminosity monitors, detector performances and preliminary results on the positron/electron luminosity ratio will be presented. Supported by NSF grants 0855473, 0959521, 1207672, and by DOE Early Career Award DE-SC0003884.

  12. Impact of the short-term luminosity evolution on luminosity function of star-forming galaxies

    Science.gov (United States)

    Parnovsky, S. L.

    2015-12-01

    An evolution of luminosity of galaxies in emission lines or wavelength ranges in which they are sensitive to the star formation process is caused by burning out of the most massive O-class stars during a few million years after a starburst. We study the impact of this effect on the luminosity function (LF) of a sample of star-forming galaxies.

  13. Development of automatic luminosity calculation framework

    CERN Document Server

    Lavicka, Roman

    2015-01-01

    Up-to-date knowledge on the collected number of events and integrated luminosity is crucial for the ALICE data taking and trigger strategy planning. The purpose of the project is to develop a framework for the automatic recalculation of achieved statistics and integrated luminosity on a daily basis using information from the ALICE data base. We have been encouraged encouraged to work on the improvement of available luminosity calculation algorithms, in particular accounting for pile-up corrections. Results are represented in a form of trending plots and summary tables for different trigger classes and stored in the personal web site of the author with an outlook on the possibility to story it in the ALICE monitoring repository.

  14. The K-Band Galaxy Luminosity Function

    OpenAIRE

    Kochanek, C. S.; Pahre, M. A.; Falco, E. E.; Huchra, J.P.; Mader, J.; Jarrett, T. H.; Chester, T.; Cutri, R.; S.E. Schneider

    2000-01-01

    We measured the K-band luminosity function using a complete sample of 4192 morphologically-typed 2MASS galaxies with 7 -0.5) galaxies have similarly shaped luminosity functions, alpha_e=-0.92+/-0.10 and alpha_l=-0.87+/-0.09. The early-type galaxies are brighter, M_*e=-23.53+/-0.06 mag compared to M_*l=-22.98\\pm0.06 mag, but less numerous, n_*e=(0.0045+/-0.0006)h^3/Mpc^3 compared to n_*l=(0.0101+/-...

  15. Offline software for the PANDA luminosity detector

    International Nuclear Information System (INIS)

    In 2018 data taking for hadronphysics facility PANDA is planned to commence. It will be build at the antiproton accelerator HESR, which itself is a part of the FAIR complex (GSI, Darmstadt, Germany). The luminosity at PANDA will be measured by a dedicated sub-detector, which will register scattered antiproton tracks from pp elastic scattering. From a software point of view, the Luminosity Detector is a tracking system. Therefore the most of its offline software parts are typical for a track reconstruction. The basic concept and Monte Carlo based performance studies of each reconstruction step is presented in this paper.

  16. THE SDSS-III BARYON OSCILLATION SPECTROSCOPIC SURVEY: THE QUASAR LUMINOSITY FUNCTION FROM DATA RELEASE NINE

    International Nuclear Information System (INIS)

    We present a new measurement of the optical quasar luminosity function (QLF), using data from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III: BOSS). From the SDSS-III Data Release Nine, a uniform sample of 22,301 i ?2, with confirmed spectroscopic redshifts between 2.2 i (z = 2.2) ? –24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log ?* – M*) for a luminosity evolution and density evolution model is found to adequately describe our data within the range 2.2 < z < 3.5; across this interval the break luminosity increases by a factor of ?2.6 while ?* declines by a factor of ?8. At z ?< 2.2 our data are reasonably well fit by a pure luminosity evolution model, and only a weak signature of ''AGN downsizing'' is seen, in line with recent studies of the hard X-ray luminosity function. We compare our measured QLF to a number of theoretical models and find that models making a variety of assumptions about quasar triggering and halo occupation can fit our data over a wide range of redshifts and luminosities

  17. Observations on the luminosity lifetimes, emittance growth rates and intra-beam scattering at the Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Paul L.G. Lebrun et al.

    2003-05-22

    A record luminosity of 4.2 10{sup 31}has been reached at the Fermilab p-{bar p} collider. The lifetime of this luminosity at the beginning of the store is about 10 hours. This lifetime can be explained by the measured loss of anti-protons and protons due to collisions and emittance growths. We report on transverse emittance growth rates based on our Synchrotron Light Monitor. Longitudinal emittance growth rate measurements are based on the TeV Sampled Bunch Display data. It is shown that Intra Beam Scattering is a significant source of emittance growth rates. We comment on other possible factors for these observed emittance growth rates. Finally, we comment on future luminosity lifetimes, as we hope to further increase our peak luminosity.

  18. LOW CO LUMINOSITIES IN DWARF GALAXIES

    International Nuclear Information System (INIS)

    We present maps of 12COJ = 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13'' angular resolution, ?250 pc at our average distance of D = 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarf galaxies outside the Local Group ranging from individual lines of sight, stacking over IR-bright regions of embedded star formation, and stacking over the entire galaxy. We detect five galaxies in CO with total CO luminosities of LCO2-1 = (3-28) × 106 K km s–1 pc2. The other 11 galaxies remain undetected in CO even in the stacked images and have LCO2-1 ?6 K km s–1 pc2. We combine our sample of dwarf galaxies with a large sample of spiral galaxies from the literature to study scaling relations of LCO with MB and metallicity. We find that dwarf galaxies with metallicities of Z ? 1/2-1/10 Z? have LCO of 2-4 orders of magnitude smaller than massive spiral galaxies and that their LCO per unit LB is 1-2 orders of magnitude smaller. A comparison with tracers of star formation (FUV and 24 ?m) shows that LCO per unit star formation rate (SFR) is 1-2 orders of magnitude smaller in dwarf galaxies. One possible interpretation is that dwarf galaxies form stars much more efficiently: we argue that the low LCO/SFR ratio is due to the fact that the CO-to-H2 conversion factor, ?CO, changes significantly in low-metallicity environments. Assuming that a constant H2 depletion time of ?dep = 1.8 Gyr holds in dwarf galaxies (as found for a large sample of nearby spirals) implies ?CO values for dwarf galaxies with Z ? 1/2-1/10 Z? that are more than one order of magnitude higher than those found in solar metallicity spiral galaxies. Such a significant increase of ?CO at low metallicity is consistent with previous studies, in particular those of Local Group dwarf galaxies that model dust emission to constrain H2 masses. Even though it is difficult to parameterize the dependence of ?CO on metallicity given the currently available data, the results suggest that CO is increasingly difficult to detect at lower metallicities. This has direct consequences for the detectability of star-forming galaxies at high redshift, which presumably have on average sub-solar metallicity.

  19. Physics as a function of energy and luminosity

    International Nuclear Information System (INIS)

    In this paper, a new physics in the range of mass up to TeV region is discussed. Most of the discussion concern hadron-hadron (hh) colliders, and also electron-positron colliders are discussed. The cross-sections for new particle production in hh colliders have the general Drell-Yan form, in which the differential luminosity for the collision of partons is included. The formulas with the parton distribution scaled up from present energy using the Altarelli-Parisi equations may be approximately correct within a factor of 2 for the production of particles. Some typical parton-parton luminosity functions for proton-proton and proton-antiproton collisions are presented. From the consideration of luminosity, it can be said that the pp colliders are to be preferred. The case studies of some of the possible new physics discussed by Zakharov, mainly on Higgs bosons and supersymmetric particles, but also a few remarks about technicolor are presented. It seems possible to detect technicolor at a large hh collider. The physics reaches of different possible hh colliders are summarized in tables. In the tables, the observable production of Higgses up to 1 TeV in mass, the observable masses for gluinos (squarks) and the technicolor observability are shown. The cleanliness of electron-positron colliders compared to hadron-hadron colliders is pled, a guess is given as to the appropriate conversion factors between the energy in the electron-positron and hh collisions, the complementarity of electron-positron and hh colliders is urged, and it is argued that a rational mix of world accelerators would include both. (Kato, T.)

  20. Using spectral flux ratios to standardize SN Ia luminosities

    Science.gov (United States)

    Bailey, S.; Aldering, G.; Antilogus, P.; Aragon, C.; Baltay, C.; Bongard, S.; Buton, C.; Childress, M.; Chotard, N.; Copin, Y.; Gangler, E.; Loken, S.; Nugent, P.; Pain, R.; Pecontal, E.; Pereira, R.; Perlmutter, S.; Rabinowitz, D.; Rigaudier, G.; Runge, K.; Scalzo, R.; Smadja, G.; Swift, H.; Tao, C.; Thomas, R. C.; Wu, C.; Nearby Supernova Factory

    2009-06-01

    We present a new method to standardize type Ia supernova (SN Ia) luminosities to ?0.13 mag using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for flux ratios that correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R642/443 = F(642~nm) / F(443~nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125 ± 0.011 mag, compared with 0.161 ± 0.015 mag when fit with the SALT2 light curve shape and color parameters x1 and c. The ratio R642/443 is an effective correction factor for both extrinsic dust reddening and instrinsic variations such as those of SN 1991T-like and SN 1999aa-like SNe. When combined with broad-band color measurements, spectral flux ratios can standardize SN Ia magnitudes to ~0.12 mag. These are the first spectral metrics that give robust improvements over the standard normalization methods based upon light curve shape and color, and they provide among the lowest scatter Hubble diagrams ever published. Table 2 is only available in electronic form at http://www.aanda.org

  1. Academic Training - LHC luminosity upgrade: detector challenges

    CERN Multimedia

    Françoise Benz

    2006-01-01

    ACADEMIC TRAINING LECTURE SERIES 13, 14, 15, March, from 11:00 to 12:00 - 16 March from 10:00 to 12:00 Main Auditorium, bldg. 500 on 14, 15 March, Council Room on 13, 16 March LHC luminosity upgrade: detector challenges A. De Roeck / CERN-PH, D. Bortoletto / Purdue Univ. USA, R. Wigmans / Texas, Tech Univ. USA, W. Riegler / CERN-PH, W. Smith / Wisconsin Univ. USA The upgrade of the LHC machine towards higher luminosity (1035 cm-2s-1) has been studied over the last few years. These studies have investigated scenarios to achieve the increase in peak luminosity by an order of magnitude, as well as the physics potential of such an upgrade and the impact of a machine upgrade on the LHC DETECTORS. This series of lectures will cover the following topics: Physics motivation and machine scenarios for an order of magnitude increase in the LHC peak luminosity (lecture 1) Detector challenges including overview of ideas for R&D programs by the LHC experiments: tracking and calorimetry, other new detector ...

  2. KEKB B-Factory, the luminosity frontier

    International Nuclear Information System (INIS)

    The experiment at the KEKB B-Factory, as well as PEP-II, brought the final blow on the 2008 Nobel Prize in Physics for the Kobayashi-Maskawa theory. A few key issues will be described on the design and performance of KEKB to make the world's highest luminosity possible. (author)

  3. MPX Detectors as LHC Luminosity Monitor

    CERN Document Server

    Sopczak, Andre; Asbah, Nedaa; Bergmann, Benedikt; Bekhouche, Khaled; Caforio, Davide; Campbell, Michael; Heijne, Erik; Leroy, Claude; Lipniacka, Anna; Nessi, Marzio; Pospisil, Stanislav; Seifert, Frank; Solc, Jaroslav; Soueid, Paul; Suk, Michal; Turecek, Daniel; Vykydal, Zdenek

    2015-01-01

    A network of 16 Medipix-2 (MPX) silicon pixel devices was installed in the ATLAS detector cavern at CERN. It was designed to measure the composition and spectral characteristics of the radiation field in the ATLAS experiment and its surroundings. This study demonstrates that the MPX network can also be used as a self-sufficient luminosity monitoring system. The MPX detectors collect data independently of the ATLAS data-recording chain, and thus they provide independent measurements of the bunch-integrated ATLAS/LHC luminosity. In particular, the MPX detectors located close enough to the primary interaction point are used to perform van der Meer calibration scans with high precision. Results from the luminosity monitoring are presented for 2012 data taken at sqrt(s) = 8 TeV proton-proton collisions. The characteristics of the LHC luminosity reduction rate are studied and the effects of beam-beam (burn-off) and beam-gas (single bunch) interactions are evaluated. The systematic variations observed in the MPX lum...

  4. RHIC Proton Luminosity and Polarization Improvement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S. Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-01-17

    The RHIC proton beam polarization can be improved by raising the Booster scraping, which also helps to reduce the RHIC transverse emittance, and therefore to improve the luminosity. By doing this, the beam-beam effect would be enhanced. Currently, the RHIC working point is constrained between 2/3 and 7/10, the 2/3 resonance would affect intensity and luminosity lifetime, and the working point close to 7/10 would enhance polarization decay in store. Run 2013 shows that average polarization decay is merely 1.8% in 8 hours, and most fills have the luminosity lifetime better than 14 hours, which is not a problem. Therefore, even without beam-beam correction, there is room to improve for RHIC polarization and luminosity. The key to push the Booster scraping is to raise the Booster input intensity; for that, two approaches can be used. The first is to extend the LINAC tank 9 pulse width, which has been successfully applied in run 2006. The second is to raise the source temperature, which has been successfully applied in run 2006 and run 2012.

  5. RHIC Proton Luminosity and Polarization Improvement

    International Nuclear Information System (INIS)

    The RHIC proton beam polarization can be improved by raising the Booster scraping, which also helps to reduce the RHIC transverse emittance, and therefore to improve the luminosity. By doing this, the beam-beam effect would be enhanced. Currently, the RHIC working point is constrained between 2/3 and 7/10, the 2/3 resonance would affect intensity and luminosity lifetime, and the working point close to 7/10 would enhance polarization decay in store. Run 2013 shows that average polarization decay is merely 1.8% in 8 hours, and most fills have the luminosity lifetime better than 14 hours, which is not a problem. Therefore, even without beam-beam correction, there is room to improve for RHIC polarization and luminosity. The key to push the Booster scraping is to raise the Booster input intensity; for that, two approaches can be used. The first is to extend the LINAC tank 9 pulse width, which has been successfully applied in run 2006. The second is to raise the source temperature, which has been successfully applied in run 2006 and run 2012.

  6. The Local Luminosity Function at 25 Microns

    CERN Document Server

    Shupe, D L; Hacking, P B; Huchra, J P; Shupe, David L.; Fang, Fan; Hacking, Perry B.; Huchra, John P.

    1998-01-01

    The local luminosity function at 25 $\\mu$m provides the basis for interpreting the results of deep mid-infrared surveys planned or in progress with space astrophysics missions including ISO, WIRE and SIRTF. We have selected a sample of 1458 galaxies from the IRAS Faint Source Survey with a flux density limit of 250 mJy at 25 $\\mu$m. The local luminosity function is derived using both parametric and non-parametric maximum-likelihood techniques, and the classical $1/V_{max}$ estimator. Comparison of these results shows that the $1/V_{max}$ estimate of the luminosity function is significantly affected by the Local Supercluster. A maximum-likelihood fit to the radial density shows no systematic increase that would be caused by density evolution of the galaxy population. The density fit is used to correct the $1/V_{max}$ estimate. We also demonstrate the high quality and completeness of our sample by a variety of methods. The luminosity function derived from this sample is compared to previously published estimate...

  7. Probing the Ultraviolet Luminosity Function of the Earliest Galaxies with the Renaissance Simulations

    Science.gov (United States)

    O'Shea, Brian W.; Wise, John H.; Xu, Hao; Norman, Michael L.

    2015-07-01

    In this paper, we present the first results from the Renaissance Simulations, a suite of extremely high-resolution and physics-rich AMR calculations of high-redshift galaxy formation performed on the Blue Waters supercomputer. These simulations contain hundreds of well-resolved galaxies at z˜ 25-8, and make several novel, testable predictions. Most critically, we show that the ultraviolet luminosity function of our simulated galaxies is consistent with observations of high-z galaxy populations at the bright end of the luminosity function ({M}1600?slant -17), but at lower luminosities is essentially flat rather than rising steeply, as has been inferred by Schechter function fits to high-z observations, and has a clearly defined lower limit in UV luminosity. This behavior of the luminosity function is due to two factors: (i) the strong dependence of the star formation rate (SFR) on halo virial mass in our simulated galaxy population, with lower-mass halos having systematically lower SFRs and thus lower UV luminosities; and (ii) the fact that halos with virial masses below ? 2× {10}8 {M}? do not universally contain stars, with the fraction of halos containing stars dropping to zero at ? 7× {10}6 {M}? . Finally, we show that the brightest of our simulated galaxies may be visible to current and future ultra-deep space-based surveys, particularly if lensed regions are chosen for observation.

  8. LIGHT and LUMINOSITY, from Einstein to LHC

    CERN Document Server

    CERN. Geneva; Prof. ROSSI, Lucio

    2015-01-01

    After an introduction on the concept of light in physics, this talk will focus on CERN’s High Luminosity LHC project, aiming at extending the discovery potential of CERN’s flagship accelerator by increasing its “luminosity” (ie the number of particles that can be squeezed inside the accelerator to maximize the number of collisions). To achieve this objective, many new technologies are being developed at CERN and many collaborating institutes worldwide, especially in the field of superconductivity. Lucio Rossi, the main speaker, is the head of the HL-LHC project, based at CERN. Giorgio Apollinari, Director for the LHC Accelerator Research Program (LARP) will speak through a videoconference from Fermilab (USA). The event is webcast live and will be followed by Fermilab and other institutes in the USA.

  9. Solar gravitational energy and luminosity variations

    CERN Document Server

    Fazel, Z; Lefebvre, S; Ajabshirizadeh, A; Pireaux, S; 10.1016/j.newst.2007.05.003

    2009-01-01

    Due to non-homogeneous mass distribution and non-uniform velocity rate inside the Sun, the solar outer shape is distorted in latitude. In this paper, we analyze the consequences of a temporal change in this figure on the luminosity. To do so, we use the Total Solar Irradiance (TSI) as an indicator of luminosity. Considering that most of the authors have explained the largest part of the TSI modulation with magnetic network (spots and faculae) but not the whole, we could set constraints on radius and effective temperature variations (dR, dT). However computations show that the amplitude of solar irradiance modulation is very sensitive to photospheric temperature variations. In order to understand discrepancies between our best fit and recent observations of Livingston et al. (2005), showing no effective surface temperature variation during the solar cycle, we investigated small effective temperature variation in irradiance modeling. We emphasized a phase-shift (correlated or anticorrelated radius and irradianc...

  10. Luminosity polarization correlation in the SLC

    International Nuclear Information System (INIS)

    In this paper we discuss the correlation between low luminosity and low polarization for off-energy particles in the Stanford Linear Collider (SLC). In the arcs of the SLC the spin of the polarized electrons has a net horizontal precession of about 25 turns. For example, a particle off energy by 1% deviates by 0.25 spin turns or a 90 degrees rotation from the core. It reduces the average polarization measured by a Compton polarimeter near the interaction point (IP)Since the energy acceptance or bandwidth of the final focus optics is limited to a certain range (? ± 0.5%), these off-energy particles are not focussed as well at the IP and thus contribute less to luminosity. Therefore, the effective polarization at the IP weighted by the luminosity is higher than the measured polarization. Relative corrections of this measured value by +0.5 to 1% for the core and another +1 to 2% for low energy beam tails seems to be necessary for the 1993 run. In 1994, beam shaping with over-compression producing lower energy spreads and smaller tails together with a new arc setup with fewer effective spin turns promise to reduce this effect by an order of magnitude

  11. Axions and the white dwarf luminosity function

    International Nuclear Information System (INIS)

    The evolution of white dwarfs can be described as a simple cooling process. Recently, it has been possible to determine with an unprecedented precision their luminosity function, that is, the number of stars per unit volume and luminosity interval. Since the shape of the bright branch of this function is only sensitive to the average cooling rate, we use this property to check the possible existence of axions, a proposed but not yet detected weakly interacting particle. We show here that the inclusion of the axion emissivity in the evolutionary models of white dwarfs noticeably improves the agreement between the theoretical calculations and the observational white dwarf luminosity function, thus providing the first positive indication that axions could exist. Our results indicate that the best fit is obtained for macos2? ? 2-6 meV, where ma is the mass of the axion and cos2? is a free parameter, and that values larger than 10 meV are clearly excluded.

  12. The Luminosity of Population III Star Clusters

    CERN Document Server

    DeSouza, Alexander L

    2015-01-01

    We analyze the time evolution of the luminosity of a cluster of Population III protostars formed in the early universe. We argue from the Jeans criterion that primordial gas can collapse to form a cluster of first stars that evolve relatively independently of one another (i.e., with negligible gravitational interaction). We model the collapse of individual protostellar clumps using 2+1D nonaxisymmetric numerical hydrodynamics simulations. Each collapse produces a protostar surrounded by a massive disk (i.e., $M_{\\rm disk} / M_{*} \\gtrsim 0.1$), whose evolution we follow for a further 30--40 kyr. Gravitational instabilities result in the fragmentation and the formation of gravitationally bound clumps within the disk. The accretion of these fragments by the host protostar produces accretion and luminosity bursts on the order of $10^6\\,\\LSun$. Within the cluster, we show that a simultaneity of such events across several protostellar cluster members can elevate the cluster luminosity to 5--10${\\times}$ greater th...

  13. Perceived area and the luminosity threshold.

    Science.gov (United States)

    Bonato, F; Gilchrist, A L

    1999-07-01

    Observers made forced-choice opaque/luminous responses to targets of varying luminance and varying size presented (1) on the wall of a laboratory, (2) as a disk within an annulus, and (3) embedded within a Mondrian array presented within a vision tunnel. Lightness matches were also made for nearby opaque surfaces. The results show that the threshold luminance value at which a target begins to appear self-luminous increases with its size, defined as perceived size, not retinal size. More generally, the larger the target, the more an increase in its luminance induces grayness/blackness into the surround and the less it induces luminosity into the target, and vice versa. Corresponding to this luminosity/grayness tradeoff, there appears to be an invariant: Across a wide variety of conditions, a target begins to appear luminous when its luminance is about 1.7 times that of a surface that would appear white in the same illumination. These results show that the luminosity threshold behaves like a surface lightness value--the maximum lightness value, in fact--and is subject to the same laws of anchoring (such as the area rule proposed by Li & Gilchrist, 1999) as surface lightness. PMID:10498995

  14. LOW CO LUMINOSITIES IN DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Schruba, Andreas; Walter, Fabian; Sandstrom, Karin [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Leroy, Adam K. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Bigiel, Frank [Institut fuer Theoretische Astrophysik, Zentrum fuer Astronomie der Universitaet Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg (Germany); Brinks, Elias [Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB (United Kingdom); De Blok, W. J. G. [Astrophysics, Cosmology and Gravity Centre, Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701 (South Africa); Kramer, Carsten [IRAM, Avenida Divina Pastora 7, 18012 Granada (Spain); Rosolowsky, Erik [Department of Physics and Astronomy, University of British Columbia Okanagan, 3333 University Way, Kelowna, BC V1V 1V7 (Canada); Schuster, Karl [IRAM, 300 rue de la Piscine, 38406 St. Martin d' Heres (France); Usero, Antonio [Observatorio Astronomico Nacional, Alfonso XII, 3, 28014 Madrid (Spain); Weiss, Axel; Wiesemeyer, Helmut, E-mail: schruba@mpia.de [MPIfR, Auf dem Huegel 69, 53121 Bonn (Germany)

    2012-06-15

    We present maps of {sup 12}COJ = 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13'' angular resolution, {approx}250 pc at our average distance of D = 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarf galaxies outside the Local Group ranging from individual lines of sight, stacking over IR-bright regions of embedded star formation, and stacking over the entire galaxy. We detect five galaxies in CO with total CO luminosities of L{sub CO2-1} = (3-28) Multiplication-Sign 10{sup 6} K km s{sup -1} pc{sup 2}. The other 11 galaxies remain undetected in CO even in the stacked images and have L{sub CO2-1} {approx}< (0.4-8) Multiplication-Sign 10{sup 6} K km s{sup -1} pc{sup 2}. We combine our sample of dwarf galaxies with a large sample of spiral galaxies from the literature to study scaling relations of L{sub CO} with M{sub B} and metallicity. We find that dwarf galaxies with metallicities of Z Almost-Equal-To 1/2-1/10 Z{sub Sun} have L{sub CO} of 2-4 orders of magnitude smaller than massive spiral galaxies and that their L{sub CO} per unit L{sub B} is 1-2 orders of magnitude smaller. A comparison with tracers of star formation (FUV and 24 {mu}m) shows that L{sub CO} per unit star formation rate (SFR) is 1-2 orders of magnitude smaller in dwarf galaxies. One possible interpretation is that dwarf galaxies form stars much more efficiently: we argue that the low L{sub CO}/SFR ratio is due to the fact that the CO-to-H{sub 2} conversion factor, {alpha}{sub CO}, changes significantly in low-metallicity environments. Assuming that a constant H{sub 2} depletion time of {tau}{sub dep} = 1.8 Gyr holds in dwarf galaxies (as found for a large sample of nearby spirals) implies {alpha}{sub CO} values for dwarf galaxies with Z Almost-Equal-To 1/2-1/10 Z{sub Sun} that are more than one order of magnitude higher than those found in solar metallicity spiral galaxies. Such a significant increase of {alpha}{sub CO} at low metallicity is consistent with previous studies, in particular those of Local Group dwarf galaxies that model dust emission to constrain H{sub 2} masses. Even though it is difficult to parameterize the dependence of {alpha}{sub CO} on metallicity given the currently available data, the results suggest that CO is increasingly difficult to detect at lower metallicities. This has direct consequences for the detectability of star-forming galaxies at high redshift, which presumably have on average sub-solar metallicity.

  15. The Luminosity Dependence of the Galaxy Merger Rate

    CERN Document Server

    Patton, D R

    2008-01-01

    We measure the number of companions per galaxy (Nc) as a function of r-band absolute magnitude for both the Sloan Digital Sky Survey and the Croton et al. (2006) semi-analytic catalog applied to the Millennium Run simulation. For close pairs with projected separations of 5-20 h^{-1} kpc, velocity differences less than 500 km/s, and luminosity ratios between 1:2 and 2:1, we find good agreement between the observations and simulations, with Nc consistently close to 0.02 over the range -22 < M_r < -18. For larger pair separations, Nc(M_r) instead becomes increasingly steep towards the faint end, implying that luminosity-dependent clustering plays an important role on small scales. Using the simulations to assess and correct for projection effects, we infer that the real-space Nc(M_r) for close pairs peaks at about M*, and declines by at least a factor of two as M_r becomes fainter. Conversely, by measuring the number density of close companions, we estimate that at least 90% of all major mergers occur betw...

  16. Remarks on the differential luminosity in the weak disruption and the transition region

    International Nuclear Information System (INIS)

    The time dependence of the different enhancement factors of the luminosity, in the region of weak disruption, has been discussed here, for the first time, and the corresponding time integral has been explicitly discussed upon. For the case of stronger disruption (transition region), the existing numerical results from various research works, has been checked analytically with the help of a square distribution

  17. Cryogenic Test of Double Quarter Wave Crab Cavity for the LHC High Luminosity Upgrade

    CERN Document Server

    Xiao, B; Belomestnykh, S; Ben-Zvi, I; Calaga, Rama; Cullen, C; Capatina, Ofelia; Hammons, L; Li, Z; Marques, C; Skaritka, J; Verdú-Andres, S; Wu, Q

    2015-01-01

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109 . We report the test results of this design.

  18. Relation between the X-ray and Optical Luminosities in Binary Systems with Accreting Nonmagnetic White Dwarfs

    CERN Document Server

    Revnivtsev, M G; Suleimanov, V F

    2014-01-01

    We investigate the relation between the optical (g-band) and X-ray (0.5-10 keV) luminosities of accreting nonmagnetic white dwarfs. According to the present-day counts of the populations of star systems in our Galaxy, these systems have the highest space density among the close binary systems with white dwarfs. We show that the dependence of the optical luminosity of accreting white dwarfs on their X-ray luminosity forms a fairly narrow one-parameter curve. The typical half-width of this curve does not exceed 0.2-0.3 dex in optical and X-ray luminosities, which is essentially consistent with the amplitude of the aperiodic flux variability for these objects. At X-ray luminosities Lx~1e32 erg/sec or lower, the optical g-band luminosity of the accretion flow is shown to be related to its X-ray luminosity by a factor ~2-3. At even lower X-ray luminosities (Lx~1e30 erg/sec), the contribution from the photosphere of the white dwarf begins to dominate in the optical spectrum of the binary system and its optical brig...

  19. Galaxy mergers and active nuclei. I. The luminosity function

    International Nuclear Information System (INIS)

    Galaxy mergers may boost the tidal disruption rate of stars near a massive central black hole in the nucleus of a galaxy, producing active galactic nuclei (AGNs) with nonthermal luminosities up to 1047 ergs s-1. We derive a bolometric luminosity function for AGNs based on this process. Our main assumptions are: (1) galaxies contain massive central black holes, and (2) the density structure of galactic nuclei is similar to that of the Milky Way. The merging rate is estimated from the two-point correlation function of galaxies. Our bolometric luminosity function can be compared with observed radio, optical, and X-ray luminosity functions by assuming that the energy emitted at these wavebands is proportional to bolometric luminosity. This assumption is based on the similarity between observed luminosity functions at high luminosities. The observed and theoretical functions have the same characteristics: at high luminosities they behave as a power law with index of about -1.4. The function flattens below L/sup direct-product/roughly-equal1044 ergs s-1. As an example we show that the model is capable of reproducing in detail the observed (bivariate) radio luminosity function. The luminosity coordinate of the break in the (bivariate) radio luminosity function at L/sup direct-product/ yields an estimate of the central black-hole mass as a function of (stellar) galactic luminosity. The space-density coordinate of the break indicates that the mean mass ratio of the interacting galaxies is larger than 20

  20. NLC Luminosity as a Function of Beam Parameters

    CERN Document Server

    Nosochkov, Yu M; Raubenheimer, T O; Seryi, Andrei

    2002-01-01

    Realistic calculation of NLC luminosity has been performed using particle tracking in DIMAD and beam-beam simulations in GUINEA-PIG code for various values of beam emittance, energy and beta functions at the Interaction Point (IP). Results of the simulations are compared with analytic luminosity calculations. The optimum range of IP beta functions for high luminosity was identified.

  1. Pin-Hole Luminosity Monitor with Feedback

    Science.gov (United States)

    Norem, James H.; Spencer, James E.

    Previously, the generalized luminosity { L} was defined and calculated for all incident channels based on an NLC e+e- design. Alternatives were then considered to improve the differing beam-beam effects in the e-e-, e? and ?? channels. Regardless of the channel, there was a large flux of outgoing, high energy photons that were produced from the beam-beam interaction e.g. beamstrahlung that needs to be disposed of and whose flux depended on { L}. One approach to this problem is to consider it a resource and attempt to take advantage of it by disposing of these straight-ahead photons in more useful ways than simply dumping them. While there are many options for monitoring the luminosity, any method that allows feedback and optimization in real time and in a non-intercepting and non-interfering way during normal data taking is extremely important - especially if it provides other capabilities such as high resolution tuning of spot sizes and can be used for all incident channels without essential modifications to their setup. Our "pin-hole" camera appears to be such a device if it can be made to work with high energy photons in ways that are compatible with the many other constraints and demands on space around the interaction region. The basis for using this method is that it has, in principle, the inherent resolution and bandwidth to monitor the very small spot sizes and their stabilities that are required for very high, integrated luminosity. While there are many possible, simultaneous uses of these outgoing photon beams, we limit our discussion to a single, blind, proof-of-principle experiment that was done on the FFTB line at SLAC to certify the concept of a camera obscura for high energy photons.

  2. Impact of the short-term luminosity evolution on luminosity function of star-forming galaxies

    CERN Document Server

    Parnovsky, S L

    2015-01-01

    An evolution of luminosity of galaxies in emission lines or wavelength ranges in which they are sensitive to the star formation process is caused by burning out of the most massive O-class stars during a few million years after a starburst. We study the impact of this effect on the luminosity function (LF) of a sample of star-forming galaxies. We introduce several types of LFs: an initial LF after a starburst, current, time-averaged and sample ones. We find the relations between them in general and specify them in the case of the luminosity evolution law proposed for the luminous compact galaxies. We obtain the sample LF for the cases the initial one is described by the pure Schechter function or the log-normal distribution and analyze the properties of these LFs. As a result we get two new types of LFs to fit the LF of a sample of star-forming galaxies.

  3. DIRC for a Higher Luminosity B Factory

    OpenAIRE

    Hadig, T.

    2003-01-01

    The DIRC, a novel type of Cherenkov ring imaging device, is the primary hadronic particle identification system for the BaBar detector at the asymmetric B-factory Pep-II at SLAC. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiators and light guides. BaBar began taking data with colliding beams in late spring 1999. This paper describes the challenges for the DIRC in a higher luminosity environment and...

  4. The Composite Luminosity Function of A496

    OpenAIRE

    Molinari, Emilio; Chincarini, Guido; Moretti, Alberto; de Grandi, Sabrina

    1998-01-01

    Deep photometric observations in three colours of the cluster A 496 show that the luminosity function is bimodal with a deep gap at g about 19.0. That is there is a net separation between E/SO galaxies that are nicely fitted by a gaussian distribution curve and the dwarfs that better match a Shechter Function. This is the first cluster observed and reduced out of a sample of 19 clusters which we have in our program. However comparison with the data of Virgo and Coma might su...

  5. New evidence for galaxy luminosity evolution

    International Nuclear Information System (INIS)

    Near-infrared photometry for 61 elliptical galaxies is used with previously published data to demonstrate that little or no color evolution is observed at infrared wavelengths, while galaxies near z = 1 are brighter than those at low redshift. Optically selected galaxies are compared with radio galaxies, and no differences in infrared properties are found. Evolution of a stellar population with an initial mass function similar to that observed in the solar neighborhood coupled with a value for q0 near 0.5 provides the best fit to the color and luminosity data

  6. Galaxy luminosity function: a new analytic expression

    Scientific Electronic Library Online (English)

    J. S., Alcaniz; J. A. S., Lima.

    2004-06-01

    Full Text Available We propose a new analytic approximation for the luminosity function of galaxies. The suggested expression behaves like the Schechter function at the faint end (f ~ La) but departs considerably at the bright end (L >> L*). We argue here that such a behavior may provide a better fit for the current ob [...] servational data than does the Schechter function. Its practical interest is stressed by considering roughly the data set provided by the Stromlo-APM redshift survey. Implications on the estimates of the matter density parameter from mass-to-light ratio are also briefly discussed.

  7. The standstill luminosity in Z Cam systems

    CERN Document Server

    Stehle, R; Rudge, C

    2000-01-01

    We consider accretion discs in close binary systems. We show that heating of a disc at the impact point of the accretion stream contributes significantly to the local energy budget at its outer edge. As a result the thermal balance relation between local accretion rate and surface density (the `S-curve') changes; the critical mass transfer rate above which no dwarf nova outbursts occur can be up to 40% smaller than without impact heating. Standstills in ZCam systems thus occur at smaller mass transfer rates than otherwise expected, and are rather fainter than the peak luminosity during the dwarf nova phase as a result.

  8. H?-luminosity of some antiflare stars

    International Nuclear Information System (INIS)

    Intensities of H?-emission line of five rapid irregular variables (SV Cep, V 530 Cyg, XY Per, VV Ser and WW Vul) have been investigated. 18 spectra of the stars were obtained at the 2.6 m telescope of the Crimean Astrophysical Observatory using the slit spectrograph with the image intensifier. H?-luminosity of four stars ranged within (0.93-16.1)x1032 erg.s-1. The variability of the emission line intensities is underlined. Spectrum of the V530 Cyg has not the bright H?-line

  9. Upgrade of RHIC Vacuum Systems for High Luminosity Operation

    CERN Document Server

    Hseuh Hsiao Chaun; Smart, Loralie; Todd, Robert J; Weiss, Daniel

    2005-01-01

    With increasing ion beam intensity during recent RHIC operations, pressure rises of several decades were observed at most room temperature sections and at a few cold sections. The pressure rises are associated with electron multi-pacting, electron stimulated desorption and beam ion induced desorption and have been one of the major intensity and luminosity limiting factors for RHIC. Improvement of the warm sections has been carried out in the last few years. Extensive in-situ bakes, additional UHV pumping, anti-grazing ridges and beam tube solenoids have been implemented. Several hundred meters of NEG coated beam pipes have been installed and activated. Vacuum monitoring and interlock were enhanced to reduce premature beam aborts. Preliminary measures, such as pumping before cool down to reduce monolayer condensates, were also taken to suppress the pressure rises in the cold sections. The effectiveness of these measures in reducing the pressure rises during machine studies and during physics runs are discussed...

  10. The Abundance of Low-luminosity Lyman alpha Emitters at High Redshift

    CERN Document Server

    Santos, M R; Kneib, J P; Richard, J; Kuijken, K; Santos, Michael R.; Ellis, Richard S.; Kneib, Jean-Paul; Richard, Johan; Kuijken, Konrad

    2004-01-01

    We derive the luminosity function of high-redshift Lyman alpha emitting sources from a deep, blind, spectroscopic survey that utilized strong-lensing magnification by intermediate-redshift clusters of galaxies. We observed carefully selected regions near 9 clusters, consistent with magnification factors generally greater than 10 for the redshift range 4.5L) proportional to L^-1 over 10^41 to 10^42.5 erg/s. When combined with the results of other surveys, limited at higher luminosities, our results suggest evidence for the suppression of star formation in low-mass halos, as predicted in popular models of galaxy formation.

  11. Luminosities for vector-boson endash vector-boson scattering at high energy colliders

    International Nuclear Information System (INIS)

    We derive exact expressions for luminosities of massive vector-boson pairs which can be used to describe the cross sections for processes in hadron collisions or e+e- annihilation which proceed via two-vector-boson scattering. Our approach correctly takes into account the mutual influence of the emission of one vector boson on the emission of a second one. We show that only approximately the exact luminosities can be factorized into convolutions of single-vector-boson distributions. Numerical results are given and compared to simplified approaches. copyright 1996 The American Physical Society

  12. LHC Report: A new luminosity record

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    After about one month of operation, the LHC has already accumulated an integrated luminosity of 28 pb-1, which corresponds to over 50% of the total delivered to the experiments in 2010. This impressive start to the LHC run in 2011 bodes well for the rest of year.   Following careful collimator set-up and validation, the first phase of beam commissioning 2011 has come to an end. The first stable beams were declared on Sunday 13 March with a moderate 3 bunches per beam and an initial luminosity of 1.6 × 1030 cm-2s-1. Machine protection tests continued during the following week as the commissioning team made absolutely sure that all critical systems (beam dumps, beam interlock system, etc.) were functioning properly. When these tests had finished, the way was opened to increased intensity and the LHC quickly moved through the first part of its planned, staged intensity increase. Fills with increasing numbers of bunches were delivered to the experiments, culminating in a fill with 200...

  13. Selected issues for the LHC luminosity upgrade

    International Nuclear Information System (INIS)

    The Large Hadron Collider started its operations on September 10. 2008. In a realistic forecast it is supposed to demonstrate (or confute) the existence of the Higgs boson for the year 2014. After this date the physics of rare events will be explored more in details and an upgrade of the luminosity can make an important difference in the program of experiments at CERN. This thesis proposes several ideas to increase the luminosity of ATLAS and CMS experiments and the acceptance of TOTEM experiment. The main object of study is the Interaction Region, that consists in the set of magnets in charge to provide the final beam focalization for the collisions. The Interaction Region is studied with the methods of beam optics and beam dynamics to design new layouts for the upgrade. These layouts are also explored from the point of view of integrability in the existing experiments developing the analysis of energy deposition and misalignment tolerances. This study was performed with the use of analytical methods for the general considerations and numerical methods for the parameters optimization. (author)

  14. Short GRBs: Rates and luminosity function implications

    CERN Document Server

    Guetta, D

    2006-01-01

    We compare the luminosity function and rate inferred from the BATSE short hard bursts (SHBs) peak flux distribution with the redshift and luminosity distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample is incompatible with SHB population that follows the star formation rate. However, it is compatible with a distribution of delay times after the SFR. This would be the case if SHBs are associated with the mergers of double neutron star (DNS) systems. DNS may be ``primordial'' or can form dynamically by binary exchange interaction in globular clusters during core collapse. The implied SHB rates that we find range from \\sim 8 to \\sim 30h_(70)^3 Gpc^(-3)yr^(-1). This rate is a much higher than what was previously estimated and, when beaming is taken into account, it is comparable to the rate of neutron star mergers estimated from statistics of binary pulsars. If GRBs are produced in mergers the implied rate practically guarantees detection by LIGO II and possibly even by LIGO I.

  15. The Evolving Luminosity Function of Red Galaxies

    CERN Document Server

    Brown, M J I; Jannuzi, B T; Brand, K; Benson, A J; Brodwin, M; Croton, D J; Eisenhardt, P R M; Brown, Michael J. I.; Dey, Arjun; Jannuzi, Buell T.; Brand, Kate; Benson, Andrew J.; Brodwin, Mark; Croton, Darren J.; Eisenhardt, Peter R.

    2006-01-01

    We trace the assembly history of red galaxies since z=1, by measuring their evolving space density with the B-band luminosity function. Our sample of 39599 red galaxies, selected from 6.96 square degrees of imaging from the NOAO Deep Wide-Field and Spitzer IRAC Shallow surveys, is an order of magnitude larger, in size and volume, than comparable samples in the literature. We measure a higher space density of z=0.9 red galaxies than some of the recent literature, in part because we account for the faint yet significant galaxy flux which falls outside of our photometric aperture. The B-band luminosity density of red galaxies, which effectively measures the evolution of ~L* galaxies, increases by only 36 percent from z=0 to z=1. If red galaxy stellar populations have faded by 1.24 B-band magnitudes since z=1, the stellar mass contained within the red galaxy population has roughly doubled over the past 8 Gyr. This is consistent with star-forming galaxies being transformed into ~L* red galaxies after a decline in ...

  16. Galaxy Luminosity Functions in WINGS clusters

    CERN Document Server

    Moretti, A; Poggianti, B M; Fasano, G; Varela, J; D'Onofrio, M; Vulcani, B; Cava, A; Fritz, J; Couch, W J; Moles, M; Kjærgaard, P

    2015-01-01

    Using V band photometry of the WINGS survey, we derive galaxy luminosity functions (LF) in nearby clusters. This sample is complete down to Mv=-15.15, and it is homogeneous, thus allowing the study of an unbiased sample of clusters with different characteristics. We constructed the photometric LF for 72 out of the original 76 WINGS clusters, excluding only those without a velocity dispersion estimate. For each cluster we obtained the LF for galaxies in a region of radius=0.5 x r200, and fitted them with single and double Schechter's functions. We also derive the composite LF for the entire sample, and those pertaining to different morphological classes. Finally we derive the spectroscopic cumulative LF for 2009 galaxies that are cluster members. The double Schechter fit parameters are neither correlated with the cluster velocity dispersion, nor with the X-ray luminosity. Our median values of the Schechter's fit slope are, on average, in agreement with measurements of nearby clusters, but are less steep that t...

  17. Thermodynamics and luminosities of rainbow black holes

    Science.gov (United States)

    Mu, Benrong; Wang, Peng; Yang, Haitang

    2015-11-01

    Doubly special relativity (DSR) is an effective model for encoding quantum gravity in flat spacetime. As result of the nonlinearity of the Lorentz transformation, the energy-momentum dispersion relation is modified. One simple way to import DSR to curved spacetime is ``Gravity's rainbow'', where the spacetime background felt by a test particle would depend on its energy. Focusing on the ``Amelino-Camelia dispersion relation'' which is E2 = m2+p2[1??(E/mp)n] with n > 0, we investigate the thermodynamical properties of a Schwarzschild black hole and a static uncharged black string for all possible values of ? and n in the framework of rainbow gravity. It shows that there are non-vanishing minimum masses for these two black holes in the cases with ? = 2. Considering effects of rainbow gravity on both the Hawking temperature and radius of the event horizon, we use the geometric optics approximation to compute luminosities of a 2D black hole, a Schwarzschild one and a static uncharged black string. It is found that the luminosities can be significantly suppressed or boosted depending on the values of ? and n.

  18. Magnet Design of the 150 mm Aperture Low-? Quadrupoles for the High Luminosity LHC

    CERN Document Server

    Ferracin, P; Anerella, M; Borgnolutti, F; Bossert, R; Cheng, D; Dietderich, D R; Felice, H; Ghosh , A; Godeke, A; Izquierdo Bermudez, S; Fessia, P; Krave, S; Juchno, M; Perez, J C; Oberli, L; Sabbi, G; Todesco, E; Yu, M

    2014-01-01

    The High Luminosity LHC (HL-LHC) project is aimed at studying and implementing the necessary changes in the LHC to increase its luminosity by a factor five. Among the magnets that will be upgraded are the 16 superconducting low-? quadrupoles placed around the two high luminosity interaction regions (ATLAS and CMS experiments). In the current baseline scenario, these quadrupole magnets will have to generate a gradient of 140 T/m in a coil aperture of 150 mm. The resulting conductor peak field of more than 12 T will require the use of Nb3Sn superconducting coils. We present in this paper the HL-LHC low-? quadrupole design, based on the experience gathered by the US LARP program, and, in particular, we describe the support structure components to pre-load the coils, withstand the electro-magnetic forces, provide alignment and LHe containment, and integrate the cold mass in the LHC IRs.

  19. Impact of Energy and Luminosity upgrades at LHC on the Physics program of ATLAS

    CERN Document Server

    Azuelos, Georges; Çakir, O; Elfgren, E; Gianotti, F; Hansen, J B; Hinchliffe, Ian; Hohlfeld, M; Jakobs, K; Leroy, C; Mehdiyev, R; Paige, Frank E; Polesello, G; Stenzel, H; Tapprogge, Stefan; Usubov, Z U; Vacavant, L

    2002-01-01

    The impact on the physics capabilities of the ATLAS detector of possible LHC upgrades is discussed. As a benchmark, an increase in the luminosity by a factor of ten is considered. For comparison, a doubling of the LHC energy is also explored. Both upgrades significantly enhance the physics capabilities of ATLAS. As measured in terms of the mass reach for new particles, the energy upgrade is more powerful. However, in cases where the effect of an upgrade is to increase the precision of measurements as a result of the larger data samples, the luminosity upgrade can be at least as powerful. The pile-up of minimum bias events at higher luminosity could limit the physics performance of ATLAS in areas where tagging of forward jets is needed.

  20. The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei

    CERN Document Server

    Bentz, Misty C; Grier, Catherine J; Barth, Aaron J; Peterson, Bradley M; Vestergaard, Marianne; Bennert, Vardha N; Canalizo, Gabriela; De Rosa, Gisella; Filippenko, Alexei V; Gates, Elinor L; Greene, Jenny E; Li, Weidong; Malkan, Matthew A; Pogge, Richard W; Stern, Daniel; Treu, Tommaso; Woo, Jong-Hak

    2013-01-01

    We present an updated and revised analysis of the relationship between the Hbeta broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of 9 new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hbeta time lag, which is assumed to yield the average Hbeta BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of alpha = 0.533 (+0.035/-0.033), consistent ...

  1. Galaxy luminosity functions in WINGS clusters

    Science.gov (United States)

    Moretti, A.; Bettoni, D.; Poggianti, B. M.; Fasano, G.; Varela, J.; D'Onofrio, M.; Vulcani, B.; Cava, A.; Fritz, J.; Couch, W. J.; Moles, M.; Kjærgaard, P.

    2015-09-01

    Aims: Using V band photometry of the WINGS survey, we derive galaxy luminosity functions (LF) in nearby clusters. This sample is complete down to MV = -15.15, and it is homogeneous, thus facilitating the study of an unbiased sample of clusters with different characteristics. Methods: We constructed the photometric LF for 72 out of the original 76 WINGS clusters, excluding only those without a velocity dispersion estimate. For each cluster we obtained the LF for galaxies in a region of radius = 0.5 × r200, and fitted them with single and double Schechter's functions. We also derive the composite LF for the entire sample, and those pertaining to different morphological classes. Finally, we derive the spectroscopic cumulative LF for 2009 galaxies that are cluster members. Results: The double Schechter fit parameters are correlated neither with the cluster velocity dispersion nor with the X-ray luminosity. Our median values of the Schechter's fit slope are, on average, in agreement with measurements of nearby clusters, but are less steep that those derived from large surveys, such as the SDSS. Early-type galaxies out number late-types at all magnitudes, but both early and late types contribute equally to the faint end of the LF. Finally, the spectroscopic LF is in excellent agreement with the one derived for A2199, A85 and Virgo, and with the photometric LF at the bright magnitudes (where both are available). Conclusions: There is a large spread in the LF of different clusters, however, this spread is not caused by correlation of the LF shape with cluster characteristics such as X-ray luminosity or velocity dispersions. The faint end is flatter than previously derived (?f = -1.7), which is at odds with that predicted from numerical simulations. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile. Progs. ID 67.A-0030, 68.A-0139, and 69.A-0119.Table 1 and full Fig. 1 (Fig. A.1) are available in electronic form at http://www.aanda.org

  2. Semiconductor detectors for high-luminosity environments

    CERN Document Server

    Collins, P

    2007-01-01

    As the final touches are being put to the LHC detectors, the race is on to perfect technologies which could be used to confront the challenges of the ultra-high luminosities of the SLHC and International Linear Collider (ILC). These challenges include ever more hostile radiation environments, short signal shaping times and increasing emphasis on the highest possible granularity combined with the lowest possible mass. In the semiconductor detector field, dedicated studies have identified many mechanisms behind radiation damage and pointed the way towards the use of new techniques such as MCz silicon and p-type sensors. In the most extreme environments, completely new approaches, such as the use of diamond or 3D sensor detectors, will be essential. Pixel technology, which has been successfully employed to build large-scale vertex detection systems for the LHC, will be pushed towards higher density, lower mass and greater integration, to satisfy in particular the ILC requirements. We review the highlights of the...

  3. Semiconductor detectors for high-luminosity environments

    CERN Document Server

    Collins, Paula

    2007-01-01

    As the final touches are being put to the LHC detectors, the race is on to perfect technologies which could be used to confront the challenges of the ultra-high luminosities of the SLHC and International Linear Collider (ILC). These challenges include ever more hostile radiation environments, short signal shaping times and increasing emphasis on the highest possible granularity combined with the lowest possible mass. In the semiconductor detector field, dedicated studies have identified many mechanisms behind radiation damage and pointed the way towards the use of new techniques such as MCz silicon and p-type sensors. In the most extreme environments, successfully employed to build large-scale vertex detection systems for the LHC, will be pushed towards higher density, lower mass and greater integration, to satisfy in particular the ILC requirements. We review the highlights of the current generation of semiconductor detectors and discuss some of the exciting prospects for future developments.

  4. Luminosity bias: from haloes to galaxies

    CERN Document Server

    Baugh, C M

    2013-01-01

    Large surveys of the local Universe have shown that galaxies with different intrinsic properties, such as colour, luminosity and morphological type display a range of clustering amplitudes. Galaxies are therefore not faithful tracers of the underlying matter distribution. This modulation of galaxy clustering, called bias, contains information about the physics behind galaxy formation. It is also a systematic to be overcome before the large-scale structure of the Universe can be used as a cosmological probe. Two types of approaches have been developed to model the clustering of galaxies. The first class is empirical and filters or weights the distribution of dark matter to reproduce the measured clustering. In the second approach an attempt is made to model the physics which governs fate of baryons in order to predict the number of galaxies in dark matter haloes. I will review the development of both approaches and summarize what we have learnt about galaxy bias.

  5. Luminosity Bias: From Haloes to Galaxies

    Science.gov (United States)

    Baugh, C. M.

    2013-04-01

    Large surveys of the local Universe have shown that galaxies with different intrinsic properties such as colour, luminosity and morphological type display a range of clustering amplitudes. Galaxies are therefore not faithful tracers of the underlying matter distribution. This modulation of galaxy clustering, called bias, contains information about the physics behind galaxy formation. It is also a systematic to be overcome before the large-scale structure of the Universe can be used as a cosmological probe. Two types of approaches have been developed to model the clustering of galaxies. The first class is empirical and filters or weights the distribution of dark matter to reproduce the measured clustering. In the second approach, an attempt is made to model the physics which governs the fate of baryons in order to predict the number of galaxies in dark matter haloes. I will review the development of both approaches and summarise what we have learnt about galaxy bias.

  6. A New Analytic Galactic Luminosity Profile Function

    CERN Document Server

    Katz, Daniel; Lenthall, Matthew; Merousis, Alex; Sundaramurthy, Navin; Kim, Jeongki

    2014-01-01

    In 2010 Spergel introduced an alternative to the traditional Sersic form for galactic luminosity profiles based on modified Bessel functions of the second kind. His motivation was the desire for an accurate one-parameter profile form with a simple Fourier transform (in contrast to the Fourier transform of the Sersic profile which can't be written in closed form), but we have found that the Spergel profile almost universally makes integrals easier when it replaces the Sersic profile in the integrand. In the original paper on the subject Spergel noted that his profile seems to fit galaxies on average just as well as Sersic's. Here we make this observation quantitative by comparing the residuals from fitting Sersic and Spergel forms to data. We find that the Spergel profile actually fits better than the Sersic for a random sample of 16 galaxies.

  7. Disruption and luminosity of flat beams

    International Nuclear Information System (INIS)

    It has been suggested (ref.1) that high energy linear colliders might operate with non-round beam profiles, i.e. with different sigma/sub x/ and sigma/sub y/, described by an aspect ratio R = sigma/sub y/sigma/sub x/. The advantage of flat beams is the expectation, that ''beamstrahlung'', i.e., beam-beam synchrotron radiation is reduced with increasing R. The reason for this reduction comes from the fact that for constant bunch area and therefore constant luminosity the mean physical distance between the particles increases with R. When the physical distances are larger, the electromagnetic fields and therefore particle acceleration and radiation decrease. This would be of particular importance for very large linear colliders (VLC), where beamstrahlung may consume an appreciable fraction of the incident energy. The underlying assumption is that the emittance quality can be preserved in the deformed bunch. 4 refs., 3 figs., 3 tabs

  8. Disruption and luminosity of flat beams

    Energy Technology Data Exchange (ETDEWEB)

    Hollebeek, R.; Minten, A.

    1985-06-10

    It has been suggested (ref.1) that high energy linear colliders might operate with non-round beam profiles, i.e. with different sigma/sub x/ and sigma/sub y/, described by an aspect ratio R = sigma/sub y/sigma/sub x/. The advantage of flat beams is the expectation, that ''beamstrahlung'', i.e., beam-beam synchrotron radiation is reduced with increasing R. The reason for this reduction comes from the fact that for constant bunch area and therefore constant luminosity the mean physical distance between the particles increases with R. When the physical distances are larger, the electromagnetic fields and therefore particle acceleration and radiation decrease. This would be of particular importance for very large linear colliders (VLC), where beamstrahlung may consume an appreciable fraction of the incident energy. The underlying assumption is that the emittance quality can be preserved in the deformed bunch. 4 refs., 3 figs., 3 tabs.

  9. Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

    Science.gov (United States)

    Norris, J. P.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Spectral lags (tau(sub lag)) are deduced for 1437 long (T(sub 90) greater than 2 s) BATSE gamma-ray bursts (GRBs) with peak flux F(sub p) greater than 0.25 photons cm(sup -2)/s, near to the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the F(sub p)-T(sub lag) plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self-consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations and for unified gamma-ray/afterglow scenarios which would account for afterglow break times and gamma-ray spectral evolution in terms of jet opening angle, viewing angle, or a profiled jet with variable Lorentz factor: A component of the burst sample is identified - those with few, wide pulses, lags of a few tenths to several seconds, and soft spectra - whose Log[N]-Log[F(sub p)] distribution approximates a -3/2 power-law, suggesting homogeneity and thus relatively nearby sources. The proportion of these long-lag bursts increases from negligible among bright BATSE bursts to approx. 50% at trigger threshold. Bursts with very long lags, approx. 1-2 less than tau(sub lag) (S) less than 10, show a tendency to concentrate near the Supergalactic Plane with a quadrupole moment of approx. -0.10 +/- 0.04. GRB 980425 (SN 1998bw) is a member of this subsample of approx. 90 bursts with estimated distances less than 100 Mpc. The frequency of the observed ultra-low luminosity bursts is approx. 1/4 that of SNe Ib/c within the same volume. If truly nearby, the core-collapse events associated with these GRBs might produce gravitational radiation detectable by LIGO-II. Such nearby bursts might also help explain flattening of the cosmic ray spectrum at ultra-high energies, as observed by AGASA.

  10. THE LUMINOSITIES OF PROTOSTARS IN THE SPITZER c2d AND GOULD BELT LEGACY CLOUDS

    International Nuclear Information System (INIS)

    Motivated by the long-standing 'luminosity problem' in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate Lbol for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 L? to 69 L?, and has a mean and median of 4.3 L? and 1.3 L?, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (Lbol ??) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 ?m bol underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.

  11. Unification of the nearby and photometric stellar luminosity functions

    CERN Document Server

    Kroupa, P

    1995-01-01

    We introduce a model Galactic field low-mass stellar population that has a proportion of binary systems as observed, with a mass ratio distribution consistent with observational constraints. The model single star and system luminosity function agrees with the nearby and the Malmquist corrected photometric luminosity function, respectively. We tabulate the model luminosity functions in the photometric V-, I- and K-bands, and in bolometric magnitudes. Unresolved binary systems are thus a natural explanation for the difference between the nearby and photometric luminosity functions. A local overdensity of faint stars needs not be postulated to account for the difference, and is very unlikely. We stress that the nearby luminosity function can only be used to weakly constrain the stellar mass function below 0.5\\,M_\\odot, because of the small sample size. The photometric luminosity function can only be used to put lower limits on the stellar mass function because most binary systems are not resolved. However, taken...

  12. Measurement of the Luminosity by the ATLAS Experiment

    CERN Document Server

    Gabaldon, C

    2011-01-01

    The luminosity is a fundamental parameter of a particle collider. The success of physics programme of ATLAS experiment depends on the precise determination of the luminosity. Several detectors have been used during the 2010-2011 data taking for the measurement of the luminosity and for monitoring its evolution as a function of time. The absolute calibration is performed using dedicated beam-separation scans which allows the determination of the luminosity without prior knowledge of the detector efficiency and inelastic pp cross section. Based on this method ATLAS has determined the luminosity with an uncertainty of 3.7%. A summary of the luminosity calibration methods and results are presented in this poster.

  13. Dependence of galaxy clustering on K-band luminosity

    Science.gov (United States)

    Deng, Xin-Fa; Qi, Xiao-Ping; Wu, Ping; Jiang, Peng; Qian, Xiao-Xia; Zhong, Shuang-Ying

    2015-08-01

    Using two volume-limited Main galaxy samples of the Sloan Digital Sky Survey Data Release 10 (SDSS DR10), we investigate K-band luminosity dependence of galaxy clustering by cluster analysis. It is found that low-luminosity galaxies are preferentially isolated or form close pairs and small groups at all scales, whereas high-luminosity galaxies preferentially inhabit dense groups and clusters.

  14. Low Luminosity Type II Supernovae: Spectroscopic and Photometric Evolution

    OpenAIRE

    Pastorello, A; Zampieri, L.; Turatto, M; Cappellaro, E; Meikle, W. P. S.; Benetti, S.; Branch, D; Baron, E; Patat, F.; ARMSTRONG, M; Altavilla, G.; De Salvo, M; Riello, M.

    2003-01-01

    In this paper we present spectroscopic and photometric observations for four core collapse supernovae (SNe), namely SNe 1994N, 1999br, 1999eu and 2001dc. Together with SN 1997D, we show that they form a group of exceptionally low-luminosity events. These SNe have narrow spectral lines (indicating low expansion velocities) and low luminosities at every phase (significantly lower than those of typical core-collapse supernovae). The very low luminosity during the ^{56}Co radioa...

  15. Using luminosity data as a proxy for economic statistics

    OpenAIRE

    Chen, Xi; Nordhaus, William D.

    2011-01-01

    A pervasive issue in social and environmental research has been how to improve the quality of socioeconomic data in developing countries. Given the shortcomings of standard sources, the present study examines luminosity (measures of nighttime lights visible from space) as a proxy for standard measures of output (gross domestic product). We compare output and luminosity at the country level and at the 1° latitude × 1° longitude grid-cell level for the period 1992–2008. We find that luminosity ...

  16. The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

    DEFF Research Database (Denmark)

    Bentz, M.C.; Denney, K.D.; Vestergaard, Marianne; Grier, C.J.; Peterson, B.M.; De Rosa, G.; Pogge, R.W.; Barth, A.J.; Bennert, V.N.; Canalizo, G.; Filippenko, A.V.; Li, W.; Gates, E.L.; Greene, J.E.; Malkan, M.A.; Stern, D.; Treu, T.; Woo, J.-H.

    2013-01-01

    We present an updated and revised analysis of the relationship between the Hß broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the opti...

  17. THE LOW-LUMINOSITY END OF THE RADIUS-LUMINOSITY RELATIONSHIP FOR ACTIVE GALACTIC NUCLEI

    Energy Technology Data Exchange (ETDEWEB)

    Bentz, Misty C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Denney, Kelly D.; Vestergaard, Marianne [Dark Cosmology Center, Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen O (Denmark); Grier, Catherine J.; Peterson, Bradley M.; De Rosa, Gisella; Pogge, Richard W. [Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA 92697 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li Weidong [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Gates, Elinor L. [University of California Observatories/Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Peyton Hall - Ivy Lane, Princeton, NJ 08544 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak, E-mail: bentz@chara.gsu.edu [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)

    2013-04-20

    We present an updated and revised analysis of the relationship between the H{beta} broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create ''AGN-free'' images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the H{beta} time lag, which is assumed to yield the average H{beta} BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R{sub BLR}-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of {alpha}= 0.533{sup +0.035}{sub -0.033}, consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 {+-} 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R{sub BLR}-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts.

  18. The low-luminosity end of the radius-luminosity relationship for active galactic nuclei

    DEFF Research Database (Denmark)

    Bentz, M.C.; Denney, K.D.

    2013-01-01

    We present an updated and revised analysis of the relationship between the Hß broad-line region (BLR) radius and the luminosity of the active galactic nucleus (AGN). Specifically, we have carried out two-dimensional surface brightness decompositions of the host galaxies of nine new AGNs imaged with the Hubble Space Telescope Wide Field Camera 3. The surface brightness decompositions allow us to create "AGN-free" images of the galaxies, from which we measure the starlight contribution to the optical luminosity measured through the ground-based spectroscopic aperture. We also incorporate 20 new reverberation-mapping measurements of the Hß time lag, which is assumed to yield the average Hß BLR radius. The final sample includes 41 AGNs covering four orders of magnitude in luminosity. The additions and updates incorporated here primarily affect the low-luminosity end of the R BLR-L relationship. The best fit to the relationship using a Bayesian analysis finds a slope of , consistent with previous work and with simple photoionization arguments. Only two AGNs appear to be outliers from the relationship, but both of them have monitoring light curves that raise doubt regarding the accuracy of their reported time lags. The scatter around the relationship is found to be 0.19 ± 0.02 dex, but would be decreased to 0.13 dex by the removal of these two suspect measurements. A large fraction of the remaining scatter in the relationship is likely due to the inaccurate distances to the AGN host galaxies. Our results help support the possibility that the R-L relationship could potentially be used to turn the BLRs of AGNs into standardizable candles. This would allow the cosmological expansion of the universe to be probed by a separate population of objects, and over a larger range of redshifts. © 2013. The American Astronomical Society. All rights reserved.

  19. The Luminosity Function and Mass Function in the Galactic Bulge

    OpenAIRE

    Holtzman, Jon A.; Watson, Alan M.; Baum, William A.; Grillmair, Carl J.; Groth, Edward J.; Light, Robert M.; Lynds, Roger; O'Neil, Earl J.

    1998-01-01

    We present deep photometry obtained with the Hubble Space Telescope (HST) in a field in Baade's Window in the Galactic bulge. We derive a luminosity function down to I ~ 24.3, or V ~ 27.5, corresponding to M ~ 0.3 Msun. The luminosity function from the turnoff down to this level appears remarkably similar to that observed in the solar neighborhood. We derive a mass function using both an empirical local mass-luminosity relation and a mass-luminosity relation from recent stel...

  20. The Morphological Type Dependence of K-band Luminosity Functions

    OpenAIRE

    Devereux, Nick; Hriljac, Paul; S. P. Willner; Ashby, M. L. N.; C.N.A. Willmer

    2009-01-01

    Differential 2.2um (K-band) luminosity functions are presented for a complete sample of 1570 nearby Vgsr < 3000 km/s, where Vgsr is the velocity measured with respect to the Galactic standard of rest), bright (K < 10 mag), galaxies segregated by visible morphology. The K-band luminosity function for late-type spirals follows a power law that rises towards low luminosities whereas the K-band luminosity functions for ellipticals, lenticulars and bulge-dominated spirals are pea...

  1. Precision measurement of the luminosity in the ATLAS experiment.

    CERN Document Server

    Hedberg, V; The ATLAS collaboration

    2011-01-01

    A precision luminosity measurement is of critical importance for the ATLAS physics program, both for searches for new physics as well as for precision measurements of Standard Model cross-sections. The calibration of the luminosity is based on so-called van der Meer scans. The calibration determines the convolved beam sizes in the vertical and horizontal directions, and together with the precise knowledge of the beam current a luminosity calibration can be determined. Based on this analysis ATLAS has determined the luminosity with a total uncertainty of only 3.7% for the 2011 data at sqrt{s}=7 TeV.

  2. Distribution of apparent magnitudes and luminosities of double galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Arakelian, M.A.

    1984-04-01

    A study is made of the influence of observational selection on the catalog distribution of the apparent magnitudes and luminosities of double galaxies. A method is proposed for constructing the luminosity function of the components of double galaxies on the basis of an arbitrary sample of pairs of galaxies. The results are applied to the data of Karachentsev's Catalog of Isolated Pairs (1972). The obtained luminosity function of the components of the pairs is almost identical to the luminosity function of randomly chosen field galaxies. The presence of a correlation between the absolute magnitudes of the components of pairs is confirmed.

  3. Does nest luminosity play a role in recognition of parasitic eggs in domed nests? A case study of the red bishop.

    Czech Academy of Sciences Publication Activity Database

    Honza, Marcel; Šulc, Michal; Cherry, M. I.

    2014-01-01

    Ro?. 101, ?. 12 (2014), s. 1009-1015. ISSN 0028-1042 Institutional support: RVO:68081766 Keywords : Brood parasitism * Domed nest * Egg discrimination * Light conditions * Nest luminosity Subject RIV: EG - Zoology Impact factor: 2.098, year: 2014

  4. Low CO Luminosities in Dwarf Galaxies

    CERN Document Server

    Schruba, Andreas; Walter, Fabian; Bigiel, Frank; Brinks, Elias; de Blok, W J G; Kramer, Carsten; Rosolowsky, Erik; Sandstrom, Karin; Schuster, Karl; Usero, Antonio; Weiss, Axel; Wiesemeyer, Helmut

    2012-01-01

    [Abridged] We present maps of CO 2-1 emission covering the entire star-forming disks of 16 nearby dwarf galaxies observed by the IRAM HERACLES survey. The data have 13 arcsec angular resolution, ~250 pc at our average distance of 4 Mpc, and sample the galaxies by 10-1000 resolution elements. We apply stacking techniques to perform the first sensitive search for CO emission in dwarfs outside the Local Group ranging from single lines-of-sight, stacked over IR-bright regions of embedded star formation, and stacked over the entire galaxy. We detect 5 dwarfs in CO with total luminosities of L_CO = 3-28 1e6 Kkmspc2. The other 11 dwarfs remain undetected in CO even in the stacked data and have L_CO < 0.4-8 1e6 Kkmspc2. We combine our sample of dwarfs with a large literature sample of spirals to study scaling relations of L_CO with M_B and metallicity. We find that dwarfs with metallicities of Z ~ 1/2-1/10 Z_sun have L_CO about 1e2-1e4x smaller than spirals and that their L_CO per unit L_B is 10-100x smaller. A co...

  5. Motion around a source whose luminosity changes

    International Nuclear Information System (INIS)

    This paper examines the motion of objects affected by changing radiation pressure from a central source. The orbits turn out to be generally unstable. Either the objects fall inward toward the source, or they are ejected from the system. If the radiation pressure has a component which flucturates in time with a dynamical frequency ?>0.845 and relative amplitude ?, circular orbits become unstable on a time scale tau/sub asterisk/approx. =?/? (in dimensionless dynamical units). If the fluctuation spectrum contains an angular variation of amplitude ? and frequency n? such that n?approx. =1 with n an integer, then it leads to unstable motion on an angular time scale theta/sub asterisk/approx. =1/a radians. If the fluctuations are stochastic with a white noise spectrum having variance sigma2, then orbits are unstable with a growth time scale sigma-2. These time scales can be quite short even for small luminosity fluctuations. Under many astronomical conditions they will dominate classical radiation-orbit interactions such as the Poynting-Robertson effect. These unstable, time-dependent motions may be important in understanding various aspects of accretion disks around black holes and neutron stars, planetary nebulae, the distribution of material around rotating and variable stars, the evolution of the proto-solar system, and the orbits of large, low-mass (e.g., artificial) satellites around the Sun

  6. Luminosity Tuning at the Large Hadron Collider

    CERN Document Server

    Wittmer, W

    2006-01-01

    By measuring and adjusting the beta-functions at the interaction point (IP the luminosity is being optimized. In LEP (Large Electron Positron Collider) this was done with the two closest doublet magnets. This approach is not applicable for the LHC (Large Hadron Collider) and RHIC (Relativistic Heavy Ion Collider) due to the asymmetric lattice. In addition in the LHC both beams share a common beam pipe through the inner triplet magnets (in these region changes of the magnetic field act on both beams). To control and adjust the beta-functions without perturbation of other optics functions, quadrupole groups situated on both sides further away from the IP have to be used where the two beams are already separated. The quadrupoles are excited in specific linear combinations, forming the so-called "tuning knobs" for the IP beta-functions. For a specific correction one of these knobs is scaled by a common multiplier. The different methods which were used to compute such knobs are discussed: (1) matching in MAD, (2)i...

  7. The Luminosities of the Coldest Brown Dwarfs

    CERN Document Server

    Tinney, C G; Kirkpatrick, J Davy; Cushing, Mike; Morley, Caroline V; Wright, Edward L

    2014-01-01

    In recent years brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500K and masses in the range 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own Solar System (at around 130K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures of in the range 1500-1000K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very-late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric colour. The latest atmospheric models show good agreement with the majority of these ...

  8. ATLAS gets its own luminosity detector

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    During the winter shutdown, the ATLAS collaboration has completed the installation of ALFA, the detector system that aims at the LHC absolute luminosity at Point 1 analysing the elastic scattering of protons at small angles.   Upper and lower ALFA Roman Pots as installed in sector 8-1 of the LHC tunnel, 240 metres from the ATLAS Interaction Point. The detectors of the ALFA system are installed at ± 240 meters from the interaction point 1, on either side of the ATLAS detector. The whole system consists of four stations, two on each side of the interaction point. Each station is equipped with two Roman Pots; each pot – that is separated from the vacuum of the accelerator by a thin window but is connected with bellows to the beam-pipe – can be moved very close to the beam. “The Roman Pot technique has been used successfully in the past for the measurement of elastic scattering very close to the circulating beam,” says Patrick Fassn...

  9. Fossil group origins. V. The dependence of the luminosity function on the magnitude gap

    Science.gov (United States)

    Zarattini, S.; Aguerri, J. A. L.; Sánchez-Janssen, R.; Barrena, R.; Boschin, W.; del Burgo, C.; Castro-Rodriguez, N.; Corsini, E. M.; D'Onghia, E.; Girardi, M.; Iglesias-Páramo, J.; Kundert, A.; Méndez-Abreu, J.; Vilchez, J. M.

    2015-09-01

    Context. In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (?m12). Thus, there are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. The observed distribution of magnitude gaps is thought to be a consequence of the orbital decay of M? galaxies in massive halos and the associated growth of the central object. As a result, to first order the amplitude of this gap is a good statistical proxy for the dynamical age of a system of galaxies. Fossil and non-fossil systems could therefore have different galaxy populations that should be reflected in their luminosity functions. Aims: In this work we study, for the first time, the dependence of the luminosity function parameters on ?m12 using data obtained by the fossil group origins (FOGO) project. Methods: We constructed a hybrid luminosity function for 102 groups and clusters at z ? 0.25 using both photometric data from the SDSS-DR7 and redshifts from the DR7 and the FOGO surveys. The latter consists of ~1200 new redshifts in 34 fossil system candidates. We stacked all the individual luminosity functions, dividing them into bins of ?m12, and studied their best-fit Schechter parameters. We additionally computed a "relative" luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differences - especially at the bright end. Results: We find trends as a function of ?m12 at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude M?. The characteristic luminosity in systems with negligible gaps is more than a factor three brighter than in fossil-like ones. Remarkably, we also find differences at the faint end. In this region, the larger the gap, the flatter the faint-end slope ?. Conclusions: The differences found at the bright end support a dissipationless, dynamical friction-driven merging model for the growth of the central galaxy in group- and cluster-sized halos. The differences in the faint end cannot be explained by this mechanism. Other processes - such as enhanced tidal disruption due to early infall and/or prevalence of eccentric orbits - may play a role. However, a larger sample of systems with ?m12> 1.5 is needed to establish the differences at the faint end.

  10. GALAXY CLUSTERING IN THE COMPLETED SDSS REDSHIFT SURVEY: THE DEPENDENCE ON COLOR AND LUMINOSITY

    International Nuclear Information System (INIS)

    We measure the luminosity and color dependence of galaxy clustering in the largest-ever galaxy redshift survey, the main galaxy sample of the Sloan Digital Sky Survey Seventh Data Release. We focus on the projected correlation function wp (rp ) of volume-limited samples, extracted from the parent sample of ?700,000 galaxies over 8000 deg2, extending up to redshift of 0.25. We interpret our measurements using halo occupation distribution (HOD) modeling assuming a ?CDM cosmology (inflationary cold dark matter with a cosmological constant). The amplitude of wp (rp ) grows slowly with luminosity for L * and increases sharply at higher luminosities, with a large-scale bias factor b(> L) x (?8/0.8) = 1.06 + 0.21(L/L*)1.12, where L is the sample luminosity threshold. At fixed luminosity, redder galaxies exhibit a higher amplitude and steeper correlation function, a steady trend that runs through the 'blue cloud' and 'green valley' and continues across the 'red sequence'. The cross-correlation of red and blue galaxies is close to the geometric mean of their autocorrelations, dropping slightly below at rp -1 Mpc. The luminosity trends for the red and blue galaxy populations separately are strikingly different. Blue galaxies show a slow but steady increase of clustering strength with luminosity, with nearly constant shape of wp (rp ). The large-scale clustering of red galaxies shows little luminosity dependence until a sharp increase at L > 4 L*, but the lowest luminosity red galaxies (0.04-0.25 L*) show very strong clustering on small scales (rp -1 Mpc). Most of the observed trends can be naturally understood within the ?CDM+HOD framework. The growth of wp (rp ) for higher luminosity galaxies reflects an overall shift in the mass scale of their host dark matter halos, in particular an increase in the minimum host halo mass Mmin. The mass at which a halo has, on average, one satellite galaxy brighter than L is M1 ? 17 Mmin(L) over most of the luminosity range, with a smaller ratio above L*. The growth and steepening of wp (rp ) for redder galaxies reflects the increasing fraction of galaxies that are satellite systems in high-mass halos instead of central systems in low-mass halos, a trend that is especially marked at low luminosities. Our extensive measurements, provided in tabular form, will allow detailed tests of theoretical models of galaxy formation, a firm grounding of semiempirical models of the galaxy population, and new constraints on cosmological parameters from combining real-space galaxy clustering with mass-sensitive statistics such as redshift-space distortions, cluster mass-to-light ratios, and galaxy-galaxy lensing.

  11. Cryogenic test of double quarter wave crab cavity for the LHC High luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, B. [Brookhaven National Lab. (BNL), Upton, NY (United States); Alberty, L. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Belomestnykh, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Ben-Zvi, I. [Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., NY (United States); Calaga, R. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Cullen, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Capatina, O. [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Hammons, L. [Brookhaven National Lab. (BNL), Upton, NY (United States); Li, Z. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Marques, C. [Brookhaven National Lab. (BNL), Upton, NY (United States); Skaritka, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Verdu-Andres, S. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Q. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    A Proof-of-Principle (PoP) Double Quarter Wave Crab Cavity (DQWCC) was designed and fabricated for the Large Hadron Collider (LHC) luminosity upgrade. A vertical cryogenic test has been done at Brookhaven National Lab (BNL). The cavity achieved 4.5 MV deflecting voltage with a quality factor above 3×109. We report the test results of this design.

  12. The luminosity function of the SMC clusters NGC152 and K3

    International Nuclear Information System (INIS)

    The luminosity functions (LF) of NGC152 and K3 have been produced from V and B plates taken with the ATT 3.8 m telescope in Australia. Photographic photometry of all good stellar images were carried out with an irisphotometer in circular areas around each cluster and in two corresponding adjoining fields. Star counts in the same areas have provided the completion factors and the derived LFs of each cluster field were normalised to equal areas. (Auth.)

  13. Hadron-hadron physics at high energy and luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Hinchliffe, I.

    1989-11-08

    I review some recent theoretical issues relevant to the physics of hadron-hadron collisions. I discuss processes where either energy or luminosity is the most important feature and emphasize the need for experiments at luminosities of 10{sup 33}cm{sup -2}sec{sup 1} if the full range of physics options is to be thoroughly explored. 22 refs., 10 figs.

  14. Bolometric Luminosity Correction of H2O Maser AGNs

    Indian Academy of Sciences (India)

    Q. Guo; J. S. Zhang; J. Wang

    2014-09-01

    For the H2O maser host AGN sample, we derived their bolometric luminosity corrections, based on their X-ray data and [O III] emission line luminosities. Our results for maser AGNs is comparable to that of non-maser AGNs.

  15. The luminosities of the coldest brown dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Tinney, C. G. [School of Physics, UNSW Australia, NSW 2052 (Australia); Faherty, Jacqueline K. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, Washington DC 20005 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, MS100-22, California Institute of Technology, Pasadena, CA 91125 (United States); Cushing, Mike [Department of Physics and Astronomy, The University of Toledo, OH 43606 (United States); Morley, Caroline V. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Wright, Edward L., E-mail: c.tinney@unsw.edu.au [Department of Physics and Astronomy, UCLA, Los Angeles, CA 90095-1547 (United States)

    2014-11-20

    In recent years, brown dwarfs have been extended to a new Y-dwarf class with effective temperatures colder than 500 K and masses in the range of 5-30 Jupiter masses. They fill a crucial gap in observable atmospheric properties between the much colder gas-giant planets of our own solar system (at around 130 K) and both hotter T-type brown dwarfs and the hotter planets that can be imaged orbiting young nearby stars (both with effective temperatures in the range of 1500-1000 K). Distance measurements for these objects deliver absolute magnitudes that make critical tests of our understanding of very cool atmospheres. Here we report new distances for nine Y dwarfs and seven very late T dwarfs. These reveal that Y dwarfs do indeed represent a continuation of the T-dwarf sequence to both fainter luminosities and cooler temperatures. They also show that the coolest objects display a large range in absolute magnitude for a given photometric color. The latest atmospheric models show good agreement with the majority of these Y-dwarf absolute magnitudes. This is also the case for WISE0855-0714, the coldest and closest brown dwarf to the Sun, which shows evidence for water ice clouds. However, there are also some outstanding exceptions, which suggest either binarity or the presence of condensate clouds. The former is readily testable with current adaptive optics facilities. The latter would mean that the range of cloudiness in Y dwarfs is substantial with most hosting almost no clouds—while others have dense clouds, making them prime targets for future variability observations to study cloud dynamics.

  16. Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

    CERN Document Server

    Cerqueira, Augusto Santiago; The ATLAS collaboration

    2015-01-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). TileCal is a sampling calorimeter with approximately 10,000 channels and is operating successfully (data quality efficiency above 99%) in ATLAS, since the start of the LHC collisions. The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10 above the original design value. The ATLAS upgrade program for high luminosity is split into three phases: Phase 0 occurred during 2013-2014 (Long Shutdown 1), and prepared the LHC for run 2; Phase 1, foreseen for 2019 (Long Shutdown 2), will prepare the LHC for run 3, whereafter the peak luminosity reaches 2-3 x 10^{34} cm^{2}s^{-1}; finally, Phase 2, which is foreseen for 2023 (Long Shutdown 3), will prepare the collider for the HL-LHC operation (5-7 x 10^{34} cm^{2}s^{-1}). The TileCal main activities for Phase 0 were the installation of the new low v...

  17. Limitation on the luminosity of e+e- storage rings due to beamstrahlung

    CERN Document Server

    Telnov, V I

    2013-01-01

    Particle loss due to the emission of single energetic beamstrahlung photons in beam collisions is shown to impose a fundamental limit on storage-ring luminosities at energies greater than 2E~140 GeV for head-on collisions and 2E~40 GeV for crab-waist collisions. Above these threshold energies, the suppression factor due to beamstrahlung scales as 1/E^{4/3}, and for a fixed power of synchrotron radiation, the luminosity L is proportional to R/E^{13/3}, where R is the collider radius. For 2E > 150 GeV, both collision schemes have similar luminosity limits. The luminosities attainable at storage-ring and linear-collider (LC) 2E=240 GeV Higgs factories are comparable; at higher energies, LCs are preferable. This conference paper is based on my recent PRL publication [1], supplemented with additional comments on linac-ring e+e- colliders and ring e+e- colliders with charge compensation (four-beam collisions).

  18. The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

    Energy Technology Data Exchange (ETDEWEB)

    Ajello, M.; Shaw, M.S.; Romani, R.W.; Dermer, C.D.; Costamante, L.; King, O.G.; Max-Moerbeck, W.; Readhead, A.; Reimer, A.; Richards, J.L.; Stevenson, M.

    2012-04-16

    Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescope we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent only {approx}0.1% of the parent population.

  19. Tile Calorimeter Upgrade Program for the Luminosity Increasing at the LHC

    CERN Document Server

    Cerqueira, Augusto Santiago; The ATLAS collaboration

    2015-01-01

    The Tile Calorimeter (TileCal) is the central hadronic calorimeter of the ATLAS experiment at the Large Hadron Collider (LHC). TileCal is a sampling calorimeter with approximately 10,000 channels and is operating successfully (data quality efficiency above 99%) in ATLAS, since the start of the LHC collisions. The LHC is scheduled to undergo a major upgrade, in 2022, for the High Luminosity LHC (HL-LHC), where the luminosity will be increased by a factor of 10 above the original design value. The ATLAS upgrade program for high luminosity is split into three phases: Phase 0 occurred during 2013-2014 (Long Shutdown 1), and prepared the LHC for run 2; Phase 1, foreseen for 2019 (Long Shutdown 2), will prepare the LHC for run 3, whereafter the peak luminosity reaches 2-3 x 10^{34} cm^{2}s^{-1}; finally, Phase 2, which is foreseen for 2024 (Long Shutdown 3), will prepare the collider for the HL-LHC operation (5-7 x 10^{34} cm^{2}s^{-1}). The TileCal main activities for Phase 0 were the installation of the new low v...

  20. GEM luminosity monitors for the OLYMPUS experiment to determine the effect of two-photon exchange

    Science.gov (United States)

    Ates, Ozgur

    The OLYMPUS experiment at DESY acquired its data in two distinct periods between 2012-2013 to measure the ratio of positron-proton and electron-proton elastic scattering cross sections. In light of those measurements, OLYMPUS will be able to quantify the effect of two-photon exchange, which is widely considered to be responsible for the discrepancy between measurements of the proton electric to magnetic form factor ratio with the Rosenbluth separation and polarization transfer methods. In order to control the systematic uncertainties to the sub-percent level, the luminosities were monitored redundantly and with high precision. This was done by measuring the rates for symmetric Moller and Bhabha scattering and by measuring the ep-elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) and MWPC (Multi-Wire Proportional Chamber technology. A total of nine GEM detectors were constructed for the OLYMPUS experiment. Within the scope of this thesis, every single step of construction, testing and installation of the GEM OLYMPUS luminosity monitors are explained in the hardware part of this thesis. Moreover, based on the analysis of the data taken with the GEM luminosity monitors at the OLYMPUS experiment, individual GEM detector performance and preliminary results on the positron/electron luminosity ratio measured with elastic scattering at forward angles are discussed in the analysis part of the thesis.

  1. Luminosity and Beam Spot Determination Using the ATLAS Detector

    CERN Document Server

    Miller, D W; The ATLAS collaboration

    2010-01-01

    We present the algorithms and results of the reconstruction of the luminous region (also known as beam spot) and measurement of the luminosity in the ATLAS experiment during the first LHC run at energies between sqrt(s) = 900 GeV (in 2009) and sqrt(s) = 7 TeV (in 2010). The LHC luminosity is determined in real time approximately once per second using a number of detectors and algorithms, each having different acceptances, systematic uncertainties and sensitivity to background. These results are displayed in the ATLAS control room and archived every two minutes; a single "preferred" measurement is reported to the LHC. During offline analysis, additional luminosity algorithms are studied and are compared to online results to further constrain systematic uncertainties on the measurement. Relative luminosities between detectors and methods agree to within a few per cent. Determination of the absolute luminosity using Monte Carlo calibrations is limited by a ~20% systematic uncertainty from the modeling of diffrac...

  2. Assessing the contribution of Centaur impacts to ice giant luminosities

    CERN Document Server

    Dodson-Robinson, Sarah E

    2015-01-01

    Voyager 2 observations revealed that the internal luminosity of Neptune is an order of magnitude higher than that of Uranus. If the two planets have similar interior structures and cooling histories, the luminosity of Neptune can only be explained by invoking some energy source beyond gravitational contraction. This paper investigates whether Centaur impacts could provide the energy necessary to produce the luminosity of Neptune. The major findings are (1) that impacts on both Uranus and Neptune are too infrequent to provide luminosities of order the observed value for Neptune, even for optimistic impact-rate estimates, and (2) that Uranus and Neptune rarely have significantly different impact-generated luminosities at any given time. Uranus and Neptune most likely have structural differences that force them to cool and contract at different rates.

  3. Simulation of the LHC BRAN luminosity monitor for high luminosity interaction regions

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, R.; Matis, H.; Ratti, A.; Stiller, J.; White, S.M.

    2010-05-23

    The BRAN (Beam RAte of Neutrals) detector monitors the collision rates in the high luminosity interaction regions of LHC (ATLAS and CMS). This Argon gas ionization detector measures the forward neutral particles from collisions at the interaction point. To predict and improve the understanding of the detector's performance, we produced a detailed model of the detector and its surroundings in Fluka. In this paper, we present the model and results of our simulations including the detectors estimated response to interactions for beam energies of 3.5, 5, and 7 TeV.

  4. Evolution of Galaxy Luminosity Function Using Photometric Redshifts

    CERN Document Server

    Ramos, B H F; Benoist, C; da Costa, L N; Maia, M A G; Makler, M; Ogando, R L C; de Simoni, F; Mesquita, A A

    2011-01-01

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end we compare LFs obtained using photometric redshifts from the CFHT Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ~4800 galaxies. We find that for z<2, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of CFHTLS comprising ~386000 galaxies to compute the LF of the combined fields and estimate directly the error in the parameters based on field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ~0.7mag from z~1.8 to z~0.3, while the characteristic density phi* increases by a factor of ~4 in the same redshift bin. We use the galaxy classification provided by the templ...

  5. Upgrade of the ATLAS Calorimeters for Higher LHC Luminosities

    CERN Document Server

    ATLAS Tile Collaboration; The ATLAS collaboration

    2015-01-01

    The upgrade of the LHC will bring instantaneous and total luminosities which are a factor 5-7 beyond the original design of the ATLAS Liquid Argon (LAr) and Tile Calorimeters and their read-out systems. Due to radiation requirements and a new two-level hardware trigger concept the read-out electronics will be improved in two phases. In Phase-I, a dedicated read-out of the LAr Calorimeters will provide higher granularity input to the trigger, in order to mitigate pile-up effects and to reduce the background rates. In Phase-II, completely new read-out electronics will allow a digital processing of all LAr and Tile Calorimeter channels at full 40 MHz bunch-crossing frequency and a transfer of calibrated energy inputs to the trigger. Results from system design and performance of the developed read-out components, including fully functioning demonstrator systems already operated on the detector, will be reported. Furthermore, the current Forward Calorimeter (FCal) may suffer from signal degradation and argon bubbl...

  6. Optical Variability Properties of High Luminosity AGN Classes

    Indian Academy of Sciences (India)

    C. S. Stalin; Gopal-Krishna; Ram Sagar; Paul J. Wiita

    2004-03-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range ? 0.2 to ? 2.2. The sample, matched in the optical luminosity – redshift (-) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), five radio core-dominated quasars (CDQs) and six BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as about 1%. Present observations cover a total of 113 nights (720 hours) with only a single qusar monitored as continuously as possible on a given night. Considering the cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 61% for RQQs, LDQs, CDQs, and BLs, respectively. The much lower amplitude and DC of INOV shown by RQQs compared to BLs may be understood in terms of their having optical synchrotron jets which are modestly misdirected from us. From our fairly extensive dataset, no general trend of a correlation between the INOVamplitude and the apparent optical brightness of the quasar is noticed. This suggests that the physical mechanisms of INOV and long term optical variability (LTOV) do not have a one-to-one relationship and different factors are involved. Also, the absence of a clear negative correlation between the INOV and LTOV characteristics of blazars of our sample points toward an inconspicuous contribution of accretion disk fluctuations to the observed INOV. The INOV duty cycle of the AGNs observed in this program suggests that INOV is associated predominantly with the highly polarized optical emission components. We also report new VLA imaging of two RQQs (1029 + 329 & 1252 + 020) in our sample which has yielded a 5 GHz detection in one of them (1252 + 020; 5GHz ? 1 mJy)

  7. Does the obscured AGN fraction really depend on luminosity?

    Science.gov (United States)

    Sazonov, S.; Churazov, E.; Krivonos, R.

    2015-12-01

    We use a sample of 151 local non-blazar active galactic nuclei (AGN) selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux-limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i.e. corrected for biases) obscured AGN fraction still shows a declining trend with luminosity, although the intrinsic obscured fraction is significantly larger than the observed one: the actual fraction is larger than ˜85 per cent at L ? 1042.5 erg s-1 (17-60 keV), and decreases to ?60 per cent at L ? 1044 erg s-1. In terms of the half-opening angle ? of an obscuring torus, this implies that ? ? 30° in lower luminosity AGN, and ? ? 45° in higher luminosity ones. If, however, the emission from the central supermassive black hole is collimated as dL/d? ? cos ?, the intrinsic dependence of the obscured AGN fraction is consistent with a luminosity-independent torus half-opening angle ? ˜ 30°.

  8. Upgrade plans for the Hadronic-Endcap Calorimeter of ATLAS for the high luminosity stage of the LHC

    CERN Document Server

    Ahmadov, Faig; The ATLAS collaboration; Cadabeschi, Mircea; Cheplakov, Alexander; Dominguez, Ruben; Fischer, Alexander; Habring, Jörg; Hambarzumjan, Armen; Javadov, Namig; Kiryunin, Andrey; Kurchaninov, Leonid; Langstaff, Roy; Lenckowski, Mark; Menke, Sven; Molinas Conde, Ignacio; Nagel, Martin; Oberlack, Horst; Raymond, Michel; Reimann, Olaf; Schacht, Peter; Strizenec, Pavol; Vogt, Sven; Wichmann, Giselher

    2015-01-01

    The expected increase of the instantaneous luminosity of a factor seven and of the total integrated luminosity by a factor 3-5 at the second phase of the upgraded high luminosity LHC compared to the design goals for LHC makes it necessary to re-evaluate the radiation hardness of the read-out electronics of the ATLAS Hadronic Endcap Calorimeter. The current cold electronics made of GaAs ASICs have been tested with neutron and proton beams to study their degradation under irradiation and the effect it would have on the ATLAS physics programme. New, more radiation hard technologies which could replace the current amplifiers have been studied as well: SiGe bipolar, Si CMOS FET and GaAs FET transistors have been irradiated with neutrons and protons with fluences up to ten times the total expected fluences for ten years of running of the high luminosity LHC. The performance measurements of the current read-out electronics and potential future technologies and expected performance degradations under high luminosity ...

  9. The UV luminosity function of nearby clusters of galaxies

    OpenAIRE

    Cortese, L.; Gavazzi, G; A. Boselli; Iglesias-Paramo, J.; Donas, J; Milliard, B

    2003-01-01

    We present the UV composite luminosity function for galaxies in the Virgo, Coma and Abell 1367 clusters. The luminosity function (LF) is well fitted by a Schechter function with M*(UV} - 5*log h(75) = -20.75 +/- 0.40 and alpha = -1.50 +/- 0.10 and does not differ significantly from the local UV luminosity function of the field. This result is in agreement with recent studies carried out in the Halpha and B-bands which find no difference between the LFs of star forming galaxi...

  10. Test Results of the Luminosity Monitors for the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Beche, J.F.; Byrd, J. M.; Doolittle, L.; Manfredi, P. F.; Matis, H. S.; Monroy, M.; Ratti, A.; Stezelberger, T.; Stiller, J.; Turner, W.; Yaver, H.; Drees, A.; Bravin, E.

    2009-05-04

    The Luminosity Monitor for the LHC has been built at LBNL and will be operational in the LHC during the upcoming run. The device, a gas ionization chamber, is installed in the high luminosity regions (those dedicated to the ATLAS and CMS experiments) and capable to resolve bunch-by-bunch luminosity as well as survive extreme levels of radiation. During the experimental R&D phase of its design, a prototype of this detector has been tested extensively at the ALS, in RHIC as well as in the SPS. Results of these experiments are presented here.

  11. Using luminosity data as a proxy for economic statistics.

    Science.gov (United States)

    Chen, Xi; Nordhaus, William D

    2011-05-24

    A pervasive issue in social and environmental research has been how to improve the quality of socioeconomic data in developing countries. Given the shortcomings of standard sources, the present study examines luminosity (measures of nighttime lights visible from space) as a proxy for standard measures of output (gross domestic product). We compare output and luminosity at the country level and at the 1° latitude × 1° longitude grid-cell level for the period 1992-2008. We find that luminosity has informational value for countries with low-quality statistical systems, particularly for those countries with no recent population or economic censuses. PMID:21576474

  12. Luminosity-related background in the Belle-II experiment

    International Nuclear Information System (INIS)

    The presently running KEKB collider will be upgraded to SuperKEKB, providing a design luminosity of 0.8 x 1036/cm2s. Accordingly, the Belle detector will be upgraded to Belle-II, with a new pixel vertex detector (PXD) close to the beampipe. The PXD is based on the DEPFET technology and has to stand a high background at full luminosity. The physics sources of the dominating luminosity- related backgrounds are discussed as well as their relevance for the PXD operation.

  13. Simulation studies of tracking systems at very high luminosity

    International Nuclear Information System (INIS)

    Detailed computer simulation studies of a tracking detector originally designed for high luminosity operation at the Superconducting Super Collider have been carried out. Detector simulation and track reconstruction techniques appropriate to the extremely high charged particle rates corresponding to luminosities of up to 1034 cm-2 s-1 are described. The detector performance is evaluated and compared to design requirements stemming from the physics goals of the SDC experiment. The results have implications for the design of tracking detectors at future high luminosity hadron colliders such as the Large Hadron Collider (LHC). (orig.)

  14. Cosmology with the Space-Luminosity Distribution of Virialized Halos

    OpenAIRE

    Marinoni, Christian; Hudson, Michael J.; Giuricin, Giuliano

    2001-01-01

    We derive the observed luminosity function of virialized systems. Coupling this statistic with the mass function predicted by CDM cosmogonies we obtain the functional behavior of the mass-to-light ratio over a wide dyna mical range in mass. We conclude that the mass-to-light ratio has a minimum close t o the luminosity of an L* galaxy halo. We also show how to derive in a self-consistent way the X-ray-to-optical luminosity ratio for galaxy systems. As a consequence, we predi...

  15. Nearby debris disk systems with high fractional luminosity reconsidered

    CERN Document Server

    Moor, A; Apai, D; Derekas, A; Grady, C; Henning, T; Kiss, C; Kiss, L L; Henning, Th.; Kiss, Cs.

    2006-01-01

    By searching the IRAS and ISO databases we compiled a list of 60 debris disks which exhibit the highest fractional luminosity values (fd>10^-4) in the vicinity of the Sun (d5x10^-4 are younger than 100Myr. The distribution of the disks in the fractional luminosity versus age diagram indicates that (1) the number of old systems with high fd is lower than was claimed before; (2) there exist many relatively young disks of moderate fractional luminosity; and (3) comparing the observations with a current theoretical model of debris disk evolution a general good agreement could be found.

  16. Perspectives for Top quark physics at High-Luminosity LHC

    CERN Document Server

    Selvaggi, Michele

    2015-01-01

    The High-Luminosity LHC is expected to provide $3 ab^{-1}$ of integrated luminosity. As a result billions of events containing top quarks will be detected at the CMS and ATLAS experiments, allowing for precise measurements of the top quark properties. The experimental challenges that will be faced in a high luminosity environment, with a special focus on top quark related observables are examined. We discuss prospects for measuring top quark anomalous couplings at the HL-LHC. Projections for detecting flavor changing neutral currents involving top quarks are also reviewed.

  17. High precision measurements of the luminosity at LEP

    International Nuclear Information System (INIS)

    The art of the luminosity measurements at LEP is presented. First generation LEP detectors have measured the absolute luminosity with the precision of 0.3-0.5%. The most precise present detectors have reached the 0.07% precision and the 0.05% is not excluded in future. Center-of-mass energy dependent relative precision of the luminosity detectors and the use of the theoretical cross-section in the LEP experiments are also discussed. (author). 18 refs., 6 figs., 6 tabs

  18. The luminosity function at z ? 8 from 97 Y-band dropouts: Inferences about reionization

    International Nuclear Information System (INIS)

    We present the largest search to date for Y-band dropout galaxies (z ? 8 Lyman break galaxies, LBGs) based on 350 arcmin2 of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin2 of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ? 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 ? mJ ? 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ? 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M?=?20.15?0.38+0.29, a faint-end slope of ?=?1.87?0.26+0.26, and a number density of log10???[Mpc?3]=?3.24?0.24+0.25. Integrated down to M = –17.7, this luminosity function yields a luminosity density log10??[erg s?1 Hz?1 Mpc?3]=25.52?0.05+0.05. Our luminosity function analysis is consistent with previously published determinations within 1?. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of reionization. By assuming theoretically motivated priors on the clumping factor and the photon escape fraction we show that the UV luminosity density from galaxy samples down to M = –17.7 can ionize only 10%-50% of the neutral hydrogen at z ? 8. Full reionization would require extending the luminosity function down to M = –15. The data are consistent with a substantial fraction of neutral hydrogen at z > 7, in agreement with recent suggestions based on deep spectroscopy of z ? 8 LBGs.

  19. High-Luminosity Large Hadron Collider (HL-LHC) Preliminary Design Report

    CERN Document Server

    Béjar Alonso, I; Brüning, O; Lamont, M; Rossi, L

    2015-01-01

    The Large Hadron Collider (LHC) is one of the largest scientific instruments ever built. Since opening up a new energy frontier for exploration in 2010, it has gathered a global user community of about 7,000 scientists working in fundamental particle physics and the physics of hadronic matter at extreme temperature and density. To sustain and extend its discovery potential, the LHC will need a major upgrade in the 2020s. This will increase its luminosity (rate of collisions) by a factor of five beyond the original design value and the integrated luminosity (total collisions created) by a factor ten. The LHC is already a highly complex and exquisitely optimised machine so this upgrade must be carefully conceived and will require about ten years to implement. The new configuration, known as High Luminosity LHC (HL-LHC), will rely on a number of key innovations that push accelerator technology beyond its present limits. Among these are cutting-edge 11-12 tesla superconducting magnets, compact superconducting cav...

  20. Evolution of the Galaxy Luminosity Function at z < 0.3

    CERN Document Server

    Loveday, J

    2004-01-01

    We measure the redshift-dependent luminosity function and the comoving radial density of galaxies in the Sloan Digital Sky Survey Data Release 1 (SDSS DR1). Both measurements indicate that the apparent number density of bright galaxies increases by a factor ~3 as redshift increases from z=0 to z=0.3. This result is robust to the assumed cosmology, to the details of the K-correction and to direction on the sky. These observations are most naturally explained by significant evolution in the luminosity and/or number density of galaxies at redshifts z < 0.3. Such evolution is also consistent with the steep number-magnitude counts seen in the APM Galaxy Survey, without the need to invoke a local underdensity in the galaxy distribution.

  1. Upgrade of the CMS Outer Tracker for the High Luminosity LHC

    CERN Document Server

    Dragicevic, Marko Gerhart

    2015-01-01

    A significant upgrade of the LHC accelerator is planned to become operational mid of the next decade. This High Luminosity LHC will increase the design luminosity by a factor of five to about 5 $\\times$ 10$^{34}$ cm$^{-2}$s$^{-1}$ or even beyond, making an upgrade of the detectors unavoidable. To cope with this environment, the outer tracker of the CMS experiment has to face an increase in particle density inducing more radiation damage and higher occupancy. Furthermore, the tracker has to provide information to the level one hardware trigger. The CMS Tracker Collaboration has developed a concept for a new tracking system, which uses intelligent dual sensor modules with high granularity. We will describe the main constituents of this new tracking detector concept.

  2. Luminosity and cooling of highly magnetised white dwarfs: Suppression of luminosity by strong magnetic fields

    CERN Document Server

    Bhattacharya, Mukul; Mukerjee, Subroto

    2015-01-01

    We investigate the luminosity and cooling of highly magnetised white dwarfs. We consider white dwarfs with electron-degenerate core and nondegenerate surface layers where cooling occurs by diffusion of photons. We find the temperature and density profiles in the surface layers or envelope of white dwarfs for radially constant and varying magnetic fields by solving the magnetostatic equilibrium and photon diffusion equations in a Newtonian framework. We also obtain the properties of white dwarfs at the core-envelope interface, when the core is assumed to be practically isothermal due to large thermal conductivity. With the increase in magnetic field, the interface temperature and density are found to be increasing. While the interface radius also increases with the increase in magnetic field when the field is hypothesised to be constant throughout the star, the interface radius decreases for varying fields. However, for white dwarfs having fixed interface radius or interface temperature, we find that the lumin...

  3. Luminosity of ultrahigh energy cosmic rays and bounds on magnetic luminosity of radio-loud active galactic nuclei

    CERN Document Server

    Coimbra-Araújo, C H

    2015-01-01

    We investigate the production of magnetic flux from rotating black holes in active galactic nuclei (AGNs) and compare it with the upper limit of ultrahigh energy cosmic ray (UHECR) luminosities, calculated from observed integral flux of GeV-TeV gamma rays for nine UHECR AGN sources. We find that, for the expected range of black hole rotations (0.44luminosities from AGNs coincides with the calculated UHECR luminosity. We argue that such result possibly can contribute to constrain AGN magnetic and dynamic properties as phenomenological tools to explain the requisite conditions to proper accelerate the highest energy cosmic rays.

  4. The relation between bar formation, galaxy luminosity, and environment

    CERN Document Server

    Corsini, E M; Sanchez-Janssen, R; Aguerri, J A L; Zarattini, S

    2013-01-01

    We derive the bar fraction in three different environments ranging from the field to Virgo and Coma clusters, covering an unprecedentedly large range of galaxy luminosities (or, equivalently, stellar masses). We confirm that the fraction of barred galaxies strongly depends on galaxy luminosity. We also show that the difference between the bar fraction distributions as a function of galaxy luminosity (and mass) in the field and Coma cluster are statistically significant, with Virgo being an intermediate case. We interpret this result as a variation of the effect of environment on bar formation depending on galaxy luminosity. We speculate that brighter disk galaxies are stable enough against interactions to keep their cold structure, thus, the interactions are able to trigger bar formation. For fainter galaxies the interactions become strong enough to heat up the disks inhibiting bar formation and even destroying the disks. Finally, we point out that the controversy regarding whether the bar fraction depends on...

  5. Measurement of the absolute luminosity with the ALEPH detector

    International Nuclear Information System (INIS)

    We report on the absolute luminosity measurement performed with the ALEPH detector at LEP. The systematic errors of the measurements in 1990 are estimated to be 0.6% (experimental) and 0.3% (theoretical). (orig.)

  6. First Results from the Pixel Luminosity Telescope (PLT)

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The Pixel Luminosity Telescope (PLT) is a silicon pixel detector dedicated to luminosity measurement at CMS. After a successful pilot run in 2012, the full PLT system, consisting of 48 pixel sensors mounted in 16 telescopes, eight on each side of CMS, was installed during LS1. The PLT provides luminosity measurements by using the ``fast-or'' capability of the pixel readout chips to find events where a hit is registered in all three sensors in a telescope, corresponding to a track from the interaction point. In addition, the full pixel data can be read out at a lower rate, allowing for measurements of efficiency, online monitoring of the data quality, and online analyses such as beamspot reconstruction, as well as enabling alternative techniques of luminosity measurement such as pixel cluster counting.

  7. the D0 Luminosity Monitor operations and performance

    Energy Technology Data Exchange (ETDEWEB)

    Prewitt, Michelle; /Rice U.

    2011-09-01

    The D0 Luminosity Monitor (LM) plays a crucial role in D0 physics analyses by providing the normalization for many cross section measurements. The detector consists of two sets of 24 scintillator wedges read out with photomultiplier tubes. The detector is located in the forward regions surrounding the beam pipe, covering a pseudo-rapidity range of 2.7 < |{eta}| < 4.4. The LM is sensitive to a large fraction of the total inelastic cross section and measures the luminosity by counting the number of empty proton-antiproton bunch crossings, using Poisson statistics to extract the instantaneous luminosity. The techniques used to convert the measurements made by the LM into the assessed luminosity will be discussed, as well as the performance and operational details of the detector.

  8. Practical and foreseeable limitations in usable luminosity for the collider

    International Nuclear Information System (INIS)

    The present situation and possible short-term improvements of the panti p collider are discussed. A long-term plan, aiming at an increase in luminosity by an order of magnitude is then described. (orig.)

  9. Layered convection as the origin of Saturn's luminosity anomaly

    CERN Document Server

    Leconte, Jérémy; 10.1038/ngeo1791

    2013-01-01

    As they keep cooling and contracting, Solar System giant planets radiate more energy than they receive from the Sun. Applying the first and second principles of thermodynamics, one can determine their cooling rate, luminosity, and temperature at a given age. Measurements of Saturn's infrared intrinsic luminosity, however, reveal that this planet is significantly brighter than predicted for its age. This excess luminosity is usually attributed to the immiscibility of helium in the hydrogen-rich envelope, leading to "rains" of helium-rich droplets. Existing evolution calculations, however, suggest that the energy released by this sedimentation process may not be sufficient to resolve the puzzle. Here, we demonstrate using planetary evolution models that the presence of layered convection in Saturn's interior, generated, like in some parts of Earth oceans, by the presence of a compositional gradient, significantly reduces its cooling. It can explain the planet's present luminosity for a wide range of configurati...

  10. The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy

    CERN Document Server

    DiPompeo, M A; Brotherton, M S; Runnoe, J C; Green, R F

    2014-01-01

    Quasar luminosity functions are a fundamental probe of the growth and evolution of supermassive black holes. Measuring the intrinsic luminosity function is difficult in practice, due to a multitude of observational and systematic effects. As sample sizes increase and measurement errors drop, characterizing the systematic effects is becoming more important. It is well known that the continuum emission from the accretion disk of quasars is anisotropic --- in part due to its disk-like structure --- but current luminosity function calculations effectively assume isotropy over the range of unobscured lines of sight. Here, we provide the first steps in characterizing the effect of random quasar orientations and simple models of anisotropy on observed luminosity functions. We find that the effect of orientation is not insignificant and exceeds other potential corrections such as those from gravitational lensing of foreground structures. We argue that current observational constraints may overestimate the intrinsic l...

  11. The Kinematics of the Lag-Luminosity Relationship

    Energy Technology Data Exchange (ETDEWEB)

    Salmonson, J D

    2004-03-17

    Herein I review the argument that kinematics, i.e. relativistic motions of the emitting source in gamma-ray bursts (GRBs), are the cause of the lag-luminosity relationship observed in bursts with known redshifts.

  12. Luminosity function of old globular clusters in the SMC

    International Nuclear Information System (INIS)

    Luminosity Functions (LFs) provide useful information on the stellar content of a star cluster. LFs of 10 SMC star clusters have been derived using photographic plates taken with the 1.2 m U.K. Schmidt telescope. (Auth.)

  13. The z=5 Quasar Luminosity Function from SDSS Stripe 82

    OpenAIRE

    McGreer, Ian D.; Jiang, Linhua; Fan, Xiaohui; Richards, Gordon T.; Strauss, Michael A.; Ross, Nicholas P.; White, Martin; SHEN, YUE; Schneider, Donald P.; Myers, Adam D.; Brandt, W. Niel; DeGraf, Colin; Glikman, Eilat; Ge, Jian; Streblyanska, Alina

    2012-01-01

    We present a measurement of the Type I quasar luminosity function at z=5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M_1450

  14. THE LUMINOSITIES OF PROTOSTARS IN THE SPITZER c2d AND GOULD BELT LEGACY CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Dunham, Michael M.; Arce, Hector G. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States); Allen, Lori E. [National Optical Astronomy Observatories, Tucson, AZ (United States); Evans II, Neal J.; Harvey, Paul M. [Department of Astronomy, University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712-1205 (United States); Broekhoven-Fiene, Hannah; Matthews, Brenda C. [Herzberg Institute, National Research Council of Canada, 5071 W. Saanich Road, Victoria, BC V9E 2E7 (Canada); Chapman, Nicholas L. [Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Department of Physics and Astronomy, 2145 Sheridan Road, Evanston, IL 60208 (United States); Cieza, Lucas A. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Gutermuth, Robert A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Hatchell, Jennifer [Astrophysics Group, Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Huard, Tracy L.; Miller, Jennifer F. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Kirk, Jason M. [School of Physics and Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff CF24 3AA (United Kingdom); Merin, Bruno [Herschel Science Centre, ESAC-ESA, P.O. Box 78, E-28691 Villanueva de la Canada, Madrid (Spain); Peterson, Dawn E. [Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, CO 80301 (United States); Spezzi, Loredana, E-mail: michael.dunham@yale.edu [European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen (Germany)

    2013-04-15

    Motivated by the long-standing 'luminosity problem' in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate L{sub bol} for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 L{sub Sun} to 69 L{sub Sun }, and has a mean and median of 4.3 L{sub Sun} and 1.3 L{sub Sun }, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L{sub bol} {approx}< 0.5 L{sub Sun }) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 {mu}m <{lambda} < 850 {mu}m) and have L{sub bol} underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source individually once additional data becomes available will likely increase both the mean and median of the sample by 35%-40%. We discuss and compare our results to several recent theoretical studies of protostellar luminosities and show that our new results do not invalidate the conclusions of any of these studies. As these studies demonstrate that there is more than one plausible accretion scenario that can match observations, future attention is clearly needed. The better statistics provided by our increased data set should aid such future work.

  15. Performance of the new high precision luminosity monitor of DELPHI

    International Nuclear Information System (INIS)

    The STIC calorimeter was installed in the DELPHI detector in 1994. The main goal is to measure the luminosity with an accuracy better than 0.1%. The calorimeter was built using the ''Shashlik'' technique. The light is collected by wavelength shifting fibers and readout by phototetrodes that can operate inside the magnetic field. The detector performance during the 1994-1995 data taking is presented. The different contributions to the systematic error on the luminosity measurement are discussed. (orig.)

  16. A composite K-band Luminosity Function for Cluster Galaxies

    OpenAIRE

    de Propris, Roberto; Christlein, Daniel

    2009-01-01

    We present a composite K-band luminosity function for 10 clusters at low redshift, where member galaxies are identified from an existing spectroscopic survey (the 2dF galaxy redshift survey). Our kinematically selected K-band luminosity function is well fitted by a Schechter function with $M^*_K=-24.50 + 5\\log h$ and $\\alpha=-0.98$ over $-27 <

  17. On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion

    OpenAIRE

    Tinker, Jeremy L; Norberg, Peder; Weinberg, David H.; Warren, Michael S.

    2006-01-01

    (Abridged) We make predictions for the pairwise velocity dispersion (PVD) of galaxies with models that are constrained to match the projected correlation function and luminosity function of galaxies in the Two-Degree Field Galaxy Redshift Survey (2dFGRS). We use these data to constrain the halo occupation distribution (HOD), then calculate the PVD by populating the halos of a high resolution N-body simulation. We examine the luminosity and scale dependence of the predicted P...

  18. Mass and luminosity evolution of young stellar objects

    OpenAIRE

    Myers, Philip C.

    2012-01-01

    A model of protostar mass and luminosity evolution in clusters gives new estimates of cluster age, protostar birthrate, accretion rate and mean accretion time. The model assumes constant protostar birthrate, core-clump accretion, and equally likely accretion stopping. Its parameters are set to reproduce the initial mass function, and to match protostar luminosity distributions in nearby star-forming regions. It obtains cluster ages and birthrates from the observed numbers of...

  19. The white dwarf luminosity function – I. Statistical errors and alternatives

    OpenAIRE

    Geijo, Enrique M.; Torres Gil, Santiago; Isern Vilaboy, Jordi; García-Berro Montilla, Enrique

    2005-01-01

    The white dwarf luminosity function is an important tool for the study of the solar neighbourhood, since it allows the determination of the age of the Galactic disc. Over the years, several methods have been proposed to compute galaxy luminosity functions, from the most simple ones – counting sample objects inside a given volume – to very sophisticated ones – like the C- method, the STY method or the Choloniewski method, among others. However, only the 1/Vmax method is usually employed in com...

  20. Implications of Lag-Luminosity Relationship for Unified GRB Paradigms

    OpenAIRE

    Norris, Jay P.

    2002-01-01

    Spectral lags are deduced for 1437 long GRBs with peak fluxes extending to near the BATSE trigger threshold. The lags are modeled to approximate the observed distribution in the peak flux-lag plane, realizing a noise-free representation. Assuming a two-branch lag-luminosity relationship, the lags are self- consistently corrected for cosmological effects to yield distributions in luminosity, distance, and redshift. The results have several consequences for GRB populations -- ...

  1. A luminosity measurement at LEP using the L3 detector

    Energy Technology Data Exchange (ETDEWEB)

    Koffeman, E.N.

    1996-06-25

    To perform high precision measurements at particle colliders it is crucial to know the exact intensity of the colliding beams. In particle physics this quantity is generally referred to as the luminosity. The determination of the luminosity in one of the experiments (L3) is the topic of this thesis. The implementation and the use of a silicon strip detector in L3, will be described in detail. In chapter one the most important parameters measured at LEP are discussed, preceded by a short introduction to the Standard Model. The process generally used for luminosity measurements in electron positron colliders is small angle Bhabha scattering. This process is discussed at the end of chapter one. In chapter two the characteristics of the collider and the L3 experiment are given. Together with the signature of the small angle Bhabha scattering, these experimental conditions determine the specifications for the design of the luminosity monitor. The general features of silicon strip detectors for their application in high energy physics are presented in chapter three. Some special attention is given to the behaviour of the sensors used for the tracking detector in the luminosity monitor. The more specific design details of the luminosity monitor are constricted to chapter four. In chapter five the conversion from detector signals into ccordinates relevant for the analysis is explained. The selection of the small angle Bhabha scattering events and the subsequent determination of the luminosity, are presented in chapter six. Systematic uncertainties are carefully studied. Important for a good understanding of the Bhabha selection are the events where a photon is produced in the scattering process. These events are separately studied. In chapter seven a comparison is presented between the radiative events observed in the data and their modelling in the Bhlumi Monte Carlo programme. (orig.).

  2. MAGNITUDE GAP STATISTICS AND THE CONDITIONAL LUMINOSITY FUNCTION

    International Nuclear Information System (INIS)

    In a recent preprint, Hearin et al. (H12) suggest that the halo mass-richness calibration of clusters can be improved by using the difference in the magnitude of the brightest and the second brightest galaxy (magnitude gap) as an additional observable. They claim that their results are at odds with the results from Paranjape and Sheth (PS12) who show that the magnitude distribution of the brightest and second brightest galaxies can be explained based on order statistics of luminosities randomly sampled from the total galaxy luminosity function. We find that a conditional luminosity function (CLF) for galaxies which varies with halo mass, in a manner which is consistent with existing observations, naturally leads to a magnitude gap distribution which changes as a function of halo mass at fixed richness, in qualitative agreement with H12. We show that, in general, the luminosity distribution of the brightest and the second brightest galaxy depends upon whether the luminosities of galaxies are drawn from the CLF or the global luminosity function. However, we also show that the difference between the two cases is small enough to evade detection in the small sample investigated by PS12. This shows that the luminosity distribution is not the appropriate statistic to distinguish between the two cases, given the small sample size. We argue in favor of the CLF (and therefore H12) based upon its consistency with other independent observations, such as the kinematics of satellite galaxies, the abundance and clustering of galaxies, and the galaxy-galaxy lensing signal from the Sloan Digital Sky Survey.

  3. Magnitude Gap Statistics and the Conditional Luminosity Function

    Science.gov (United States)

    More, Surhud

    2012-12-01

    In a recent preprint, Hearin et al. (H12) suggest that the halo mass-richness calibration of clusters can be improved by using the difference in the magnitude of the brightest and the second brightest galaxy (magnitude gap) as an additional observable. They claim that their results are at odds with the results from Paranjape & Sheth (PS12) who show that the magnitude distribution of the brightest and second brightest galaxies can be explained based on order statistics of luminosities randomly sampled from the total galaxy luminosity function. We find that a conditional luminosity function (CLF) for galaxies which varies with halo mass, in a manner which is consistent with existing observations, naturally leads to a magnitude gap distribution which changes as a function of halo mass at fixed richness, in qualitative agreement with H12. We show that, in general, the luminosity distribution of the brightest and the second brightest galaxy depends upon whether the luminosities of galaxies are drawn from the CLF or the global luminosity function. However, we also show that the difference between the two cases is small enough to evade detection in the small sample investigated by PS12. This shows that the luminosity distribution is not the appropriate statistic to distinguish between the two cases, given the small sample size. We argue in favor of the CLF (and therefore H12) based upon its consistency with other independent observations, such as the kinematics of satellite galaxies, the abundance and clustering of galaxies, and the galaxy-galaxy lensing signal from the Sloan Digital Sky Survey.

  4. A luminosity measurement at LEP using the L3 detector

    International Nuclear Information System (INIS)

    To perform high precision measurements at particle colliders it is crucial to know the exact intensity of the colliding beams. In particle physics this quantity is generally referred to as the luminosity. The determination of the luminosity in one of the experiments (L3) is the topic of this thesis. The implementation and the use of a silicon strip detector in L3, will be described in detail. In chapter one the most important parameters measured at LEP are discussed, preceded by a short introduction to the Standard Model. The process generally used for luminosity measurements in electron positron colliders is small angle Bhabha scattering. This process is discussed at the end of chapter one. In chapter two the characteristics of the collider and the L3 experiment are given. Together with the signature of the small angle Bhabha scattering, these experimental conditions determine the specifications for the design of the luminosity monitor. The general features of silicon strip detectors for their application in high energy physics are presented in chapter three. Some special attention is given to the behaviour of the sensors used for the tracking detector in the luminosity monitor. The more specific design details of the luminosity monitor are constricted to chapter four. In chapter five the conversion from detector signals into ccordinates relevant for the analysis is explained. The selection of the small angle Bhabha scattering events and the subsequent determination of the luminosity, are presented in chapter six. Systematic uncertainties are carefully studied. Important for a good understanding of the Bhabha selection are the events where a photon is produced in the scattering process. These events are separately studied. In chapter seven a comparison is presented between the radiative events observed in the data and their modelling in the Bhlumi Monte Carlo programme. (orig.)

  5. Low-luminosity X-ray sources and the Galactic ridge X-ray emission

    CERN Document Server

    Warwick, R S

    2014-01-01

    Using the XMM-Newton Slew Survey, we construct a hard-band selected sample of low-luminosity Galactic X-ray sources. Two source populations are represented, namely coronally-active stars and binaries (ASBs) and cataclysmic variables (CVs), with X-ray luminosities collectively spanning the range 10^(28-34) erg/s (2-10 keV). We derive the 2-10 keV X-ray luminosity function (XLF) and volume emissivity of each population. Scaled to the local stellar mass density, the latter is found to be 1.08 +/- 0.16 x 10^28 erg/s/M and 2.5 +/- 0.6 x 10^27 erg/s/M, for the ASBs and CVs respectively, which in total is a factor 2 higher than previous estimates. We employ the new XLFs to predict the X-ray source counts on the Galactic plane at l = 28.5 deg and show that the result is consistent with current observational constraints. The X-ray emission of faint, unresolved ASBs and CVs can account for a substantial fraction of the Galactic ridge X-ray emission (GRXE). We discuss a model in which roughly 80 per cent of the 6-10 keV...

  6. The GOODS-MUSIC Sample: Evolution of the Luminosity Function of Red and Blue Galaxies

    Science.gov (United States)

    Salimbeni, S.; Giallongo, E.; Grazian, A.

    2007-12-01

    Using data from the GOODS public survey we analysed the galaxy properties in terms of the colour and specific star formation rate (SSFR) distributions. More specifically we analysed the galaxy bimodal distribution up to relatively high redshift (z ?q 3). We used these properties to separate the galaxy sample in two populations (red-blue using colour; early-late using SSFR). We have then studied the evolution of the red/early and blue/late luminosity function (LF) and of the luminosity density. For the blue galaxies we find a luminosity evolution with a brightening of M^* in the z=0.2-1 interval and at higher redshift a constant LF. For the red sample, we find at the bright-end of the LF a constant density in the range 0.2-0.67 and a density reduction by a factor 5 up to redshift 3.5. For the red population we also find a characteristic shape for the LF, with a minimum around M_B(AB)=-18 and with a turn up at fainter magnitude. This shape has been represented by a double Schechter function.

  7. The Dependence of Type Ia Supernova Luminosities on their Host Galaxies

    CERN Document Server

    Sullivan, M; Howell, D A; Neill, J D; Astier, P; Balland, C; Basa, S; Carlberg, R G; Fouchez, D; Guy, J; Hardin, D; Hook, I M; Pain, R; Palanque-Delabrouille, N; Perrett, K M; Pritchet, C J; Regnault, N; Rich, J; Ruhlmann-Kleider, V; Baumont, S; Hsiao, E; Kronborg, T; Lidman, C; Perlmutter, S; Walker, E S

    2010-01-01

    (Abridged) Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN Ia luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) and other data, we show that there is an additional dependence on the global characteristics of their host galaxies: events of the same light-curve shape and colour are, on average, 0.08mag (~4.0sigma) brighter in massive host galaxies (presumably metal-rich) and galaxies with low specific star-formation rates (sSFR). SNe Ia in galaxies with a low sSFR also have a smaller slope ("beta") between their luminosities and colours with ~2.7sigma significance, and a smaller scatter on SN Ia Hubble diagrams (at 95% confidence), though the significance of these effects is dependent on the reddest SNe. SN Ia colours are similar between low-mass and high-mass hosts, leading us to interpret their luminosity differences as an intrinsic property of the SNe and not of some external factor such as dust. If the host stellar mass is in...

  8. Studies of Read-Out Electronics and Trigger for Muon Drift Tube Detectors at High Luminosities

    CERN Document Server

    Nowak, Sebastian

    The Large Hadron Collider (LHC) at the European Centre for Particle Physics, CERN, collides protons with an unprecedentedly high centre-of-mass energy and luminosity. The collision products are recorded and analysed by four big experiments, one of which is the ATLAS detector. For precise measurements of the properties of the Higgs-Boson and searches for new phenomena beyond the Standard Model, the LHC luminosity of $L=10^{34}cm^{-2}s^{-1}$ is planned to be increased by a factor of ten leading to the High Luminosity LHC (HL-LHC). In order to cope with the higher background and data rates, the LHC experiments need to be upgraded. In this thesis, studies for the upgrade of the ATLAS Muon Spectrometer are presented with respect to the read-out electronics of the Monitored Drift Tube (MDT) and the small-diameter Muon Drift Tube (sMDT) chambers and the Level-1 muon trigger. Due to the reduced tube diameter of sMDT chambers, background occupancy and space charge effects are suppressed by an order of magnitude compar...

  9. LHCb: LHCb Muon System Performance at High Luminosity

    CERN Multimedia

    Pinci, D

    2013-01-01

    The LHCb detector was conceived to operate with an average Luminosity of $2 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. During the last year of LHC run, the whole apparatus has shown to be able to perfectly acquire and manage data produced at a Luminosity as high as $4 \\times 10^{32}$ cm$^{-2}$ s$^{-1}$. In these conditions, all sub-detectors operated at average particle rates higher than the design ones and in particular the Multi-Wire Proportional Chambers equipping the Muon System had to sustain a particle rate as high as 250 kHz/cm$^{2}$. In order to study the possibility of increasing the Luminosity of operation of the whole experiment several tests were performed. The effective beam Luminosity at the interaction point of LHCb was increased in several steps up to $10^{33}$ cm$^{-2}$ s$^{-1}$ and in each step the behavior of all the detectors in the Muon System was recorded. The data analysis has allowed to study the performance of the Muon System as a function of the LHC Luminosity and the results are r...

  10. Magnitude Gap Statistics and the Conditional Luminosity Function

    CERN Document Server

    More, Surhud

    2012-01-01

    In a recent preprint, Hearin et al. (2012,H12) suggest that the halo mass-richness calibration of clusters can be improved by using the difference in the magnitude of the brightest and the second brightest galaxy (magnitude gap) as an additional observable. They claim that their results are at odds with the results from Paranjape & Sheth (2012, PS12) who show that the magnitude distribution of the brightest and second brightest galaxies can be explained based on order statistics of luminosities randomly sampled from the total galaxy luminosity function. We find that a conditional luminosity function (CLF) for galaxies which varies with halo mass, in a manner which is consistent with existing observations, naturally leads to a magnitude gap distribution which changes as a function of halo mass at fixed richness, in qualitative agreement with H12. We show that, in general, the luminosity distribution of the brightest and the second brightest galaxy depends upon whether the luminosities of galaxies are drawn...

  11. On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion

    CERN Document Server

    Tinker, J L; Weinberg, D H; Warren, M S; Tinker, Jeremy L.; Norberg, Peder; Weinberg, David H.; Warren, Michael S.

    2006-01-01

    (Abridged) We make predictions for the pairwise velocity dispersion (PVD) of galaxies with models that are constrained to match the projected correlation function and luminosity function of galaxies in the Two-Degree Field Galaxy Redshift Survey (2dFGRS). We use these data to constrain the halo occupation distribution (HOD), then calculate the PVD by populating the halos of a high resolution N-body simulation. We examine the luminosity and scale dependence of the predicted PVD. At r3 Mpc/h, we find that the PVD decreases with increasing galaxy luminosity. This result is mostly driven by the fraction of satellite galaxies f_sat, which is well-constrained by the correlation function. We find f_sat~25% for galaxies fainter than L_star, while for brighter galaxies the satellite fraction rapidly declines, creating the decrease in the PVD with luminosity. At r=1 Mpc/h, the PVD has no dependence on luminosity because satellite galaxies dominate the statistics for all objects. Recent measurements of the PVD in Fourie...

  12. Does the obscured AGN fraction really depend on luminosity?

    CERN Document Server

    Sazonov, Sergey; Krivonos, Roman

    2015-01-01

    We use a sample of 151 local non-blazar AGN selected from the INTEGRAL all-sky hard X-ray survey to investigate if the observed declining trend of the fraction of obscured (i.e. showing X-ray absorption) AGN with increasing luminosity is mostly an intrinsic or selection effect. Using a torus-obscuration model, we demonstrate that in addition to negative bias, due to absorption in the torus, in finding obscured AGN in hard X-ray flux limited surveys, there is also positive bias in finding unobscured AGN, due to Compton reflection in the torus. These biases can be even stronger taking into account plausible intrinsic collimation of hard X-ray emission along the axis of the obscuring torus. Given the AGN luminosity function, which steepens at high luminosities, these observational biases lead to a decreasing observed fraction of obscured AGN with increasing luminosity even if this fraction has no intrinsic luminosity dependence. We find that if the central hard X-ray source in AGN is isotropic, the intrinsic (i....

  13. The critical accretion luminosity for magnetized neutron stars

    CERN Document Server

    Mushtukov, Alexander A; Tsygankov, Sergey S; Poutanen, Juri

    2014-01-01

    The accretion flow around X-ray pulsars with a strong magnetic field is funnelled by the field to relatively small regions close to the magnetic poles of the neutron star (NS), the hotspots. During strong outbursts regularly observed from some X-ray pulsars, the X-ray luminosity can be so high, that the emerging radiation is able to stop the accreting matter above the surface via radiation-dominated shock, and the accretion column begins to rise. This border luminosity is usually called the "critical luminosity". Here we calculate the critical luminosity as a function of the NS magnetic field strength $B$ using exact Compton scattering cross section in strong magnetic field. Influence of the resonant scattering and photon polarization is taken into account for the first time. We show that the critical luminosity is not a monotonic function of the B-field. It reaches a minimum of a few 10^{36} erg s^{-1} when the cyclotron energy is about 10 keV and a considerable amount of photons from a hotspot have energy c...

  14. Galactic Distribution and the Luminosity Function of Pulsars

    CERN Document Server

    Yusifov, I

    2004-01-01

    We have studied the radial distribution and luminosity function of normal pulsars in the Galaxy, on the basis of the ATNF Pulsar Catalogue where the distances are calculated according to the new electron density model NE2001. We show that the maximum of galactocentric distribution of pulsars located near 3.5 kpc and the scale-length of this distribution is nearly 4 kpc. The surface density of pulsars near the Galactic center (GC) is equal or slightly higher than that in the solar neighborhood. The local density and birth-rate of pulsars is 1.5 and 4 times higher than previous estimates, correspondingly before and after beaming corrections. The dependence of these results on the NE2001 model and recommendations for further improvement of the electron density distribution are discussed. We derived the luminosity function of pulsars at frequencies near 1400 MHz. In the limited band of luminosities, the luminosity function has a slope near -1, but a new luminosity function may be better fitted by a Log-Normal dis...

  15. An early separation scheme for the LHC luminosity upgrade

    CERN Document Server

    Sterbini, G

    2010-01-01

    The present document is organized in five chapters. In the first chapter the framework of the study is described, developing the motivations, the goals and the requirements for the LHC Luminosity Upgrade. We analyze the need for the crossing angle and its impact on the peak luminosity of the collider. After having introduced the Early Separation Scheme, we explain how it may overcome some limitations of the present machine. We compare the nominal LHC crossing scheme with the proposed one underlining its potential in terms of performance and its issues with respect to the integration in the detectors. An analysis of the integrated magnetic field required is given. In the second chapter we introduce one of the most powerful aspect of the scheme: the luminosity leveling. After the description of the physical model adopted, we compare the results of its analytical and numerical solutions. All the potential improvement due to the Early Separation Scheme are shown on the luminosity plane (peak luminosity versus int...

  16. Development of Silicon Detectors for the High Luminosity LHC

    International Nuclear Information System (INIS)

    The Large Hadron Collider (LHC) at CERN will be upgraded to a High Luminosity LHC in the year 2022, increasing the instantaneous luminosity by a factor of five. This will have major impacts on the experiments at the LHC, such as the Compact Muon Solenoid (CMS) experiment, and especially for their inner silicon tracking systems. Among other things, the silicon sensors used therein will be exposed to unprecedented levels of radiation damage, necessitating a replacement of the entire tracking detector. In order to maintain the excellent current performance, a new tracking detector has to be equipped with sensors of increased radiation hardness and higher granularity. The CMS experiment is undertaking an extensive R and D campaign in the search for the future silicon sensor technology baseline to be used in this upgrade. This thesis presents two methods suitable for use in this search: finite element TCAD simulations and test beam measurements. The simulations are focussed on the interstrip capacitance between sensor strips and are compared to measurements before and after the inclusion of radiation damage effects. A geometrical representation of the strip sensors used in the campaign has been found, establishing the predictive power of simulations. The test beam measurements make use of the high-precision pixel telescopes available at the DESY-II test beam facility. The performance of these telescopes has been assessed and their achievable pointing resolution has been found to be below 2 ?m. Thin, epitaxial silicon is a candidate material for usage in radiation hard sensors for the future CMS tracking detector. Sample strip sensors of this material have been irradiated to fluences of up to 1.3 x 1016 neq/cm2 with 800 MeV or 23 GeV protons. Test beam measurements with 5 GeV electrons have been performed to investigate the radiation hardness of epitaxial sensors using the pixel beam telescopes. The epitaxial device under test (DUT) has been integrated into the telescope and its software analysis framework. An alignment of DUT and telescope planes has been performed and traversing particle tracks reconstructed for the sensor analysis. Results show that the achievable resolution in the epitaxial silicon strip sensors is at the binary level. The measured charge collection efficiency for p-bulk sensors amounts to 80% of pre-irradiation levels for fluences of 3 x 1015 neq/cm2 and to over 65% for ? = 1.3 x 1016 neq/cm2. Signal-to-noise levels at these fluence levels are 7.4 and 3.8, respectively. With particle tracks of various inclinations, the sharing of charge between sensor strips is investigated. Indications of possible charge losses at the sensor surface are described and evidence of commencing charge multiplication effects is presented. Sensors are also compared to thicker, non epitaxial sensors irradiated to the same fluence. From the obtained results, acquired from the first test beam measurements of irradiated epitaxial sensors ever performed, a complete picture of this material has been gained. It can be concluded that thin, p-bulk epitaxial silicon is sufficiently radiation hard for usage as an outer pixel detector sensor material.

  17. TOOLS FOR COMPUTING THE AGN FEEDBACK: RADIO-LOUDNESS DISTRIBUTION AND THE KINETIC LUMINOSITY FUNCTION

    International Nuclear Information System (INIS)

    We studied the active galactic nucleus (AGN) radio emission from a compilation of hard X-ray-selected samples, all observed in the 1.4 GHz band. A total of more than 1600 AGNs with 2-10 keV de-absorbed luminosities higher than 1042 erg s-1 cm-2 were used. For a sub-sample of about fifty z ?X = log(L 1.4/LX ), where L 1.4/LX = ?L ?(1.4 GHz)/LX (2-10 keV). The probability distribution function of RX was functionally fitted as dependent on the X-ray luminosity and redshift, P(RX |LX , z). It roughly spans over six decades (-7X X ratio increases with decreasing X-ray luminosities and (possibly) with increasing redshift. No statistically significant difference was found between the radio properties of the X-ray absorbed (N H>1022 cm-2) and un-absorbed AGNs. Measurement of the probability distribution function of RX allowed us to compute the kinetic luminosity function and the kinetic energy density which, at variance with that assumed in many galaxy evolution models, is observed to decrease by about a factor of 5 at redshift below 0.5. About half of the kinetic energy density results in being produced by the more radio quiet (RX kin in converting the accreted mass energy into kinetic power (LK=?kin m-dot c2) is, on average, ?kin ? 5 x 10-3. The data suggest a possible increase of ?kin at low redshifts.

  18. Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity

    Science.gov (United States)

    Tomsick, John A.; Yamoka, Kazutaka; Corbel, Stephane; Kaaret, Philip; Kalemci, Emrah; Migliari, Simone

    2011-01-01

    Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R(sub in)) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R(sub in) is very close to the black hole at high and moderate luminosities (greater than or equal to 1% of the Eddington luminosity, L(sub Edd). Here, we report on X-ray observations of the black hole GX 339-4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer that extend iron line studies to 0.14% L(sub Edd) and show that R(sub in) increases by a factor of greater than 27 over the value found when GX 339-4 was bright. The exact value of R(sub in) depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R(sub in) greater than 35 R(sub g) at i = 0 degrees and R(sub in) greater than 175 R(sub g) at i = 30 degrees. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing for the possibility that the inner disk is replaced by advection- or magnetically dominated accretion flows.

  19. ATLAS Future Plans: Upgrade and the Physics with High Luminosity

    Directory of Open Access Journals (Sweden)

    Rajagopalan S.

    2013-05-01

    Full Text Available The ATLAS experiment is planning a series of detector upgrades to cope with the planned increases in instantaneous luminosity and multiple interactions per crossing to maintain its physics capabilities. During the coming decade, the Large Hadron Collider will collide protons on protons at a center of mass energy up to 14 TeV with luminosities steadily increasing in a phased approach to over 5 × 1034 cm?2s?1. The resulting large data sets will significantly enhance the physics reach of the ATLAS detector building on the recent discovery of the Higgs-like boson. The planned detector upgrades being designed to cope with the increasing luminosity and its impact on the ATLAS physics program will be discussed.

  20. The UV luminosity function of nearby clusters of galaxies

    CERN Document Server

    Cortese, L; Boselli, A; Iglesias-Páramo, J; Donas, J; Milliard, B

    2003-01-01

    We present the UV composite luminosity function for galaxies in the Virgo, Coma and Abell 1367 clusters. The luminosity function (LF) is well fitted by a Schechter function with M*(UV} - 5*log h(75) = -20.75 +/- 0.40 and alpha = -1.50 +/- 0.10 and does not differ significantly from the local UV luminosity function of the field. This result is in agreement with recent studies carried out in the Halpha and B-bands which find no difference between the LFs of star forming galaxies in clusters and in the field. This indicates that, whatever mechanisms are responsible for quenching the star formation in clusters, they influence similarly the giant and the dwarf populations, leaving the shape of the LF unchanged and only modifying its normalization.

  1. Analysis of Luminosity Data in BaBar

    International Nuclear Information System (INIS)

    Luminosity is a value describing the number of interactions between particles when their respective beams collide. The BaBar (B and B-bar) ambient database and the Oracle server contain archived measurements of instantaneous luminosity from two separate detectors. It is important to understand these data to describe the performance of the B-Factory. Extracting these data, the more reliable PEP-II (Positron Electron Two) luminosity detector can be calibrated to the data collected by the more accurate BaBar L3 (Level 3) detector. Using the ROOT programming language and standard BaBar tools for data extraction, graphs and statistics are generated. Some logistical errors contained in the logbook are also corrected. These programs help aid in understanding both what is happening within the B-Factory, as well as the correlations between the interrelationship of detector data and the information recorded in the logbook

  2. Pixel Luminosity Telescope (PLT) calibration and first measurements

    CERN Document Server

    CMS Collaboration

    2015-01-01

    The Pixel Luminosity Telescope is a new complement to the CMS detector for the LHC Run II data taking period. It consists of eight 3-layer telescopes based on silicon pixel detectors that are placed around the beam pipe on each side of CMS viewing the interaction point at small angle. A fast 3-fold coincidence of the pixel planes in each telescope will provide a bunch-by-bunch measurement of the luminosity. Particle tracking allows collision products to be distinguished from beam background, provides a self-alignment of the detectors, and provides for continuous in-time monitoring of the efficiency of each telescope plane. The PLT is an independent luminometer, essential to reduce the uncertainty on the delivered luminosity. This will allow to determine production cross sections, and hence couplings, with higher precision and to set more stringent limits on new particle production.

  3. The bulge luminosity for low-mass black holes

    CERN Document Server

    Jiang, Yanfei; Ho, Luis

    2011-01-01

    We study the scaling between bulge magnitude and central black hole (BH) mass in galaxies with virial BH masses 10^7 solar mass. Specfically, bulges span a much wider range of bulge luminosity, and on average the luminosity is larger, at fixed black hole mass. The trend holds both for the active galaxies from Bentz et al. and the inactive sample of Gultekin et al. and cannot be explained by differences in stellar populations, as it persists when we use dynamical bulge masses. Put another way, the ratio between bulge and BH mass is much larger than $\\sim 1000$ for our sample. This is consistent with recent suggestions that black hole mass does not scale with the pseudobulge luminosity. The low-mass scaling relations appear to flatten, consistent with predictions from Volonteri & Natarajan for massive seed BHs.

  4. High luminosity ?+ ?- collider: Report of a feasibility study

    International Nuclear Information System (INIS)

    Parameters are given of 4 TeV and 0.5 TeV (c-of-m) high luminosity ?+?- colliders, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders, starting from the proton accelerator needed to generate the muons and proceeding through muon cooling, acceleration and storage in a collider ring. Detector background, polarization, and nonstandard operating conditions are analyzed. Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should thus be regarded as complementary. We briefly mention the luminosity requirements of hadrons and lepton machines and their high-energy-physics advantages and disadvantages in reference to their effective center of mass energy. Finally, we present an R ampersand D plan to determine whether such machines are practical

  5. Report of the Working Group on High Luminosities at LEP

    International Nuclear Information System (INIS)

    The availability of an order-of-magnitude increase in the luminosity of LEP (CERN's Large Electron-Positron Collider) can dramatically increase its physics output. With the help of a pretzel scheme, it should be possible to increase the peak luminosity beyond 1032 cm-2 s-1 at the Z energy and to significantly increase the luminosity around the W-pari threshold. This report spells out the physics possibilities opened up by the availability of several 107Z events. The three domains of physics that benefit mostly from this abundance are very accurate measurements of Standard Model parameters, rare decays of the Z, and the physics of fermion-antifermion states such as B physics. The possibilities and implications for the machine and the experiments are presented. The physics possibilities are explored and compared with those at other accelerators. (orig.)

  6. Higgs pair production at the High Luminosity LHC

    CERN Document Server

    CMS Collaboration

    2015-01-01

    Studies of the Higgs boson pair production and decays into $bb\\gamma\\gamma$, $bb\\tau\\tau$, and $bb\\mathrm{W}\\mathrm{W}$ final states are presented. The studies are performed assuming the operational conditions of the High-Luminosity LHC, with an integrated luminosity of 3000~$\\mathrm{fb}^{-1}$, and the upgraded CMS experiment. Combining the studies of $bb\\gamma\\gamma$ and $bb\\tau\\tau$ final states, the expected significance for Higgs boson pair production is 1.9 standard deviation. The resulting expected uncertainty in the signal yield is $54\\%$. The benefits of the CMS Phase-II upgrade, to meet the challenges presented by the high luminosity environment, are emphasized.

  7. Mass and luminosity evolution of young stellar objects

    CERN Document Server

    Myers, Philip C

    2012-01-01

    A model of protostar mass and luminosity evolution in clusters gives new estimates of cluster age, protostar birthrate, accretion rate and mean accretion time. The model assumes constant protostar birthrate, core-clump accretion, and equally likely accretion stopping. Its parameters are set to reproduce the initial mass function, and to match protostar luminosity distributions in nearby star-forming regions. It obtains cluster ages and birthrates from the observed numbers of protostars and pre-main sequence (PMS) stars, and from the modal value of the protostar luminosity. In 31 embedded clusters and complexes the global cluster age is 1-3 Myr, matching available estimates based on optical spectroscopy and evolutionary tracks. This method of age estimation is simpler than optical spectroscopy, and is more useful for young embedded clusters where optical spectrocopy is not possible. In the youngest clusters, the protostar fraction decreases outward from the densest gas, indicating that the local star-forming a...

  8. Feasibility of electron cooling and luminosity potentials of colliders

    International Nuclear Information System (INIS)

    Luminosity upgrades of colliders with hadron beams tend to require decreased and maintained beam emittances using a suitable cooling technique. The breakthroughs of recent years: realization of beam energy recovery in superconducting linear accelerators; flat to round beam transformations; and new beam transport concepts (discontinuous solenoid, circulator rings, hollow beams, dispersive cooling); have promoted the feasibility of efficient electron cooling of intense high energy hadron beams. Electron cooling, in cooperation with strong SRF fields in storage rings, will allow one to obtain very short hadron bunches, as result of which the luminosity can be raised by making a low beta-star. Short bunches also would make feasible crab crossing, that allows one to remove the parasitic beam-beam interactions and maximize the collision rate. Cooling also results in flatness of uncoupled beam equilibrium; this can be used to diminish the IBS impact on luminosity

  9. Reduction of beta* and increase of luminosity at RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Pilat,F.; Bai, M.; Bruno, D.; Cameron, P.; Della Penna, A.; Drees, A.; Litvinenko, V.; Luo, Y.; Malitsky, N.; Marr, G.; Ptitsyn, V.; Satogata, T.; Tepikian, S.; Trbojevic, D.

    2009-05-04

    The reduction of {beta}* beyond the 1m design value at RHIC has been consistently achieved over the last 6 years of RHIC operations, resulting in an increase of luminosity for different running modes and species. During the recent 2007-08 deuteron-gold run the reduction to 0.70 from the design 1m achieved a 30% increase in delivered luminosity. The key ingredients allowing the reduction have been the capability of efficiently developing ramps with tune and coupling feedback, orbit corrections on the ramp, and collimation, to minimize beam losses in the final focus triplets, the main aperture limitations for the collision optics. We will describe the operational strategy used to reduce the {beta}*, at first squeezing the beam at store, to test feasibility, followed by the operationally preferred option of squeezing the beam during acceleration, and the resulting luminosity increase. We will conclude with future plans for the beta squeeze.

  10. Bimodality in low luminosity E and S0 galaxies

    CERN Document Server

    Sansom, A E

    2008-01-01

    Stellar population characteristics are presented for a sample of low luminosity early-type galaxies (LLEs) in order to compare them with their more luminous counterparts. Long-slit spectra of a sample of 10 LLEs were taken with the ESO New Technology Telescope, selected for their low luminosities. Line strengths were measured on the Lick standard system. Lick indices for these LLEs were correlated with velocity dispersion (sigma), alongside published data for a variety of Hubble types. The LLEs were found to fall below an extrapolation of the correlation for luminous ellipticals and were consistent with the locations of spiral bulges in plots of line strengths versus sigma. Luminosity weighted average ages, metallicities and abundance ratios were estimated from chi-squared fitting of 19 Lick indices to predictions from simple stellar population models. The LLEs appear younger than luminous ellipticals and of comparable ages to spiral bulges. These LLEs show a bimodal metallicity distribution, consisting of a ...

  11. MODELING THE RED SEQUENCE: HIERARCHICAL GROWTH YET SLOW LUMINOSITY EVOLUTION

    International Nuclear Information System (INIS)

    We explore the effects of mergers on the evolution of massive early-type galaxies by modeling the evolution of their stellar populations in a hierarchical context. We investigate how a realistic red sequence population set up by z ? 1 evolves under different assumptions for the merger and star formation histories, comparing changes in color, luminosity, and mass. The purely passive fading of existing red sequence galaxies, with no further mergers or star formation, results in dramatic changes at the bright end of the luminosity function and color-magnitude relation. Without mergers there is too much evolution in luminosity at a fixed space density compared to observations. The change in color and magnitude at a fixed mass resembles that of a passively evolving population that formed relatively recently, at z ? 2. Mergers among the red sequence population ('dry mergers') occurring after z = 1 build up mass, counteracting the fading of the existing stellar populations to give smaller changes in both color and luminosity for massive galaxies. By allowing some galaxies to migrate from the blue cloud onto the red sequence after z = 1 through gas-rich mergers, younger stellar populations are added to the red sequence. This manifestation of the progenitor bias increases the scatter in age and results in even smaller changes in color and luminosity between z = 1 and z = 0 at a fixed mass. The resultant evolution appears much slower, resembling the passive evolution of a population that formed at high redshift (z ? 3-5), and is in closer agreement with observations. We conclude that measurements of the luminosity and color evolution alone are not sufficient to distinguish between the purely passive evolution of an old population and cosmologically motivated hierarchical growth, although these scenarios have very different implications for the mass growth of early-type galaxies over the last half of cosmic history.

  12. Research and Development for a Free-Running Readout System for the ATLAS LAr Calorimeters at the High Luminosity LHC

    CERN Document Server

    Hils, Maximilian; The ATLAS collaboration

    2015-01-01

    The ATLAS Liquid Argon (LAr) Calorimeters were designed and built to measure electromagnetic and hadronic energy in proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and instantaneous luminosities up to $10^{34} \\text{cm}^{-2} \\text{s}^{-1}$. The High Luminosity LHC (HL-LHC) programme is now developed for up to 5-7 times the design luminosity, with the goal of accumulating an integrated luminosity of $3000~\\text{fb}^{-1}$. In the HL-LHC phase, the increased radiation levels require a replacement of the front-end electronics of the LAr Calorimeters. Furthermore, the ATLAS trigger system is foreseen to increase the trigger accept rate by a factor 10 to 1 MHz and the trigger latency by a factor of 20 which requires a larger data volume to be buffered. Therefore, the LAr Calorimeter read-out will be exchanged with a new front-end and a high bandwidth back-end system for receiving data from all 186.000 channels at 40 MHz LHC bunch-crossing frequency and for off-detector buffering...

  13. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main-sequence stars

    Science.gov (United States)

    Mendigutía, I.; Oudmaijer, R. D.; Rigliaco, E.; Fairlamb, J. R.; Calvet, N.; Muzerolle, J.; Cunningham, N.; Lumsden, S. L.

    2015-09-01

    Correlations between the accretion luminosity and emission line luminosities (Lacc and Lline) of pre-main-sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) Lacc-Lline correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L*) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the Lacc-Lline correlations depend on the Lacc-L* relationship. We conclude that because PMS stars show the Lacc-L* correlation immediately implies that Lacc also correlates with the luminosity of all emission lines, for which the Lacc-Lline correlations alone do not prove any physical connection with accretion but can only be used with practical purposes to roughly estimate accretion rates. When looking for correlations with possible physical meaning, we suggest that Lacc/L* and Lline/L* should be used instead of Lacc and Lline. Finally, the finding that Lacc has a steeper dependence on L* for T Tauri stars than for intermediate-mass Herbig Ae/Be stars is also discussed. That is explained from the magnetospheric accretion scenario and the different photospheric properties in the near-UV.

  14. On the origin of the correlations between the accretion luminosity and emission line luminosities in pre-main sequence stars

    CERN Document Server

    Mendigutía, I; Rigliaco, E; Fairlamb, J R; Calvet, N; Muzerolle, J; Cunningham, N; Lumsden, S L

    2015-01-01

    Correlations between the accretion luminosity and emission line luminosities (L_acc and L_line) of pre-main sequence (PMS) stars have been published for many different spectral lines, which are used to estimate accretion rates. Despite the origin of those correlations is unknown, this could be attributed to direct or indirect physical relations between the emission line formation and the accretion mechanism. This work shows that all (near-UV/optical/near-IR) L_acc-L_line correlations are the result of the fact that the accretion luminosity and the stellar luminosity (L_star) are correlated, and are not necessarily related with the physical origin of the line. Synthetic and observational data are used to illustrate how the L_acc-L_line correlations depend on the L_acc-L_star relationship. We conclude that because PMS stars show the L_acc-L_star correlation immediately implies that L_acc also correlates with the luminosity of all emission lines, for which the L_acc-L_line correlations alone do not prove any phy...

  15. The Radius-Luminosity Relationship for Active Galactic Nuclei

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.; Netzer, Hagai; Pogge, Richard W.; Vestergaard, Marianne

    2009-01-01

    We present high-resolution HST images of all 35 AGNs with optical reverberation-mapping results, which we have modeled to create a nucleus-free image of each AGN host galaxy. From the nucleus-free images, we determine the host-galaxy contribution to ground-based spectroscopic luminosity measurements at 5100A. After correcting the luminosities of the AGNs for the contribution from starlight, we re-examine the Hbeta R-L relationship. Our best fit for the relationship gives a powerlaw slope of 0.52...

  16. Beam-beam interaction: luminosity, tails, and noise

    International Nuclear Information System (INIS)

    Observations of the beam-beam interaction at SPEAR, CESR, PETRA and PEP are discussed. They are sufficiently similar that a simple prescription can be formulated to describe the behavior of the luminosity as a function of current including the peak values. With this prescription the interpretation of various methods of increasing the luminosity, such as the reduction of the vertical betatron function, the increase of the horizontal beam size, and mini- and micro- beta projects, is straight-forward. Predictions for future storage rings can also be made. Finally, some observations of the consequences of reducing the vertical betatron function to near the value of the bunch length are discussed

  17. The Main Sequence Luminosity Function of Palomar 5 from HST

    OpenAIRE

    Grillmair, Carl J.; Smith, Graeme H.

    2001-01-01

    A low mass, large core radius, and strong tidal tails suggest that the globular cluster Palomar 5 has lost a large fraction of its initial mass over time. If the dynamical evolution of Palomar 5 has been dominated by the effects of mass loss, then the luminosity function should be deficient in low-mass stars. Using deep WFPC2 F555W and F814W photometry, we determine the main sequence luminosity functions both near the cluster center and in a field near the half-light radius....

  18. On the Interpretation of the Globular Cluster Luminosity Function

    OpenAIRE

    Kruijssen, J. M. Diederik; Zwart, Simon F. Portegies

    2009-01-01

    The conversion of the globular cluster luminosity function (GCLF, dN/dlogL) to the globular cluster mass function (GCMF, dN/dlogM) is addressed. Dissolving globular clusters (GCs) become preferentially depleted in low-mass stars, which have a high mass-to-light ratio. This has been shown to result in a mass-to-light ratio (M/L) that increases with GC luminosity or mass, because more massive GCs have lost a smaller fraction of their stars than low-mass GCs. Using GC models, w...

  19. Theoretical Models of Multi-waveband QSO Luminosity Functions

    OpenAIRE

    Hosokawa, T; Mineshige, S.; Kawaguchi, T; Yoshikawa, K.; Umemura, M

    2001-01-01

    Cosmological evolution of the QSO luminosity functions (LFs) at NIR/optical/X-ray bands for 1.3 < z < 3.5 is investigated based on the realistic QSO spectra. The accretion-disk theory predicts that although QSO luminosities only depend on mass-accretion rate, \\Mdot, QSO spectra have a dependence on black-hole mass, M_{BH}, as well. The smaller M_{BH} is and/or the larger \\Mdot is, the harder becomes the QSO NIR/optical/UV spectrum. We model disk spectra which can reproduce t...

  20. Parameter Space for the LHC High-Luminosity Upgrade

    CERN Document Server

    Bruning, Oliver

    2012-01-01

    We review the parameter space for the high-luminosity upgrade of the LHC (HL-LHC). Starting from the luminosity targets and the primary limitations, e.g., event pile up, turnaround time, injector limits, and intrabeam scattering, we determine compatible beam parameters such as the beam intensity, bunch spacing, transverse and longitudinal emittances, bunch length, and IP beta functions required to meet the HL-LHC goals. Possible HL-LHC parameter sets together with their expected performance reach are presented for comparison and discussion.

  1. Online calculation of the Tevatron collider luminosity using accelerator instrumentation

    International Nuclear Information System (INIS)

    The luminosity of a collision region may be calculated if one understands the lattice parameters and measures the beam intensities, the transverse and longitudinal emittances, and the individual proton and antiproton beam trajectories (space and time) through the collision region. This paper explores an attempt to make this calculation using beam instrumentation during Run 1b of the Tevatron. The instrumentation used is briefly described. The calculations and their uncertainties are compared to luminosities calculated independently by the Collider Experiments (CDF and D0)

  2. Fast and precise luminosity measurement at the international linear collider

    Indian Academy of Sciences (India)

    C Grah; on behalf of the FCAL Collaboration

    2007-12-01

    The detectors of the ILC will feature a calorimeter system in the very forward region. The system comprises mainly two electromagnetic calorimeters: LumiCal, which is dedicated to the measurement of the absolute luminosity with highest precision and BeamCal, which uses the energy deposition from beamstrahlung pairs for a fast luminosity measure and the determination of beam parameters. The FCAL system is designed as a universal system fitting all detector concepts. It was implemented and simulated as a subsystem of the large detector concept [1]. The studies are carried out within the FCAL collaboration.

  3. Luminosity-Limiting Coherent Phenomena in Electron-Positron Colliders

    Science.gov (United States)

    Krishnagopal, S.

    1996-01-01

    We have developed a new simulation program that correctly models the transverse beam-beam dynamics of beams with arbitrary distribution and ellipticity, in e+e- colliders. We find that the dynamics, and hence the achievable luminosity, is limited by two kinds of coherent phenomena-the flip-flop effect and period- n beam-size oscillations. While both solutions coexist, the former are typically stronger and occur at lower currents than the latter. These results are in broad agreement with experimental observations, and suggest that greater care needs to be taken in the choice of operating parameters of the high-luminosity B factories that are presently under construction.

  4. Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

    Science.gov (United States)

    Baudrenghien, P.; Mastoridis, T.

    2015-10-01

    The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of ?* to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

  5. Cosmic downsizing of powerful radio galaxies to low radio luminosities

    CERN Document Server

    Rigby, E E; Best, P N; Rosario, D; Röttgering, H J A

    2015-01-01

    At bright radio powers ($P_{\\rm 1.4 GHz} > 10^{25}$ W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution persists for sources an order of magnitude fainter than those previously studied, by measuring the steep--spectrum radio luminosity function (RLF) across the range $10^{24} 10^{26}$ W/Hz the redshift of the peak space density increases with luminosity, whilst at lower radio luminosities the position of the peak remains constant within the uncertainties. This `cosmic downsizing' behaviour is found to be similar to that seen at optical wavelengths for quasars, and is interpreted as representing the transition from radiatively efficient to inefficient accretion modes in the steep-spectrum population. This conclusion is supported by constructing simple models for the space density evolution of these two different radio galaxy classes; these are able to successfully reproduce the ...

  6. A new record peak luminosity for the LHC

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Two weeks of dedicated machine development paid off last weekend when the LHC ran for physics with three nominal intensity (?1011 protons) bunches in each beam.   This brought a new record peak luminosity of around 8×1029 cm-2 s-1, and allowed the LHC to double the integrated luminosity delivered to the experiments since 30 March from 16 to 32 inverse nanobarns over the weekend. After a few more fills in this configuration, the number of bunches will be raised to six per beam, which will in turn allow the peak luminosity to break the 1030 cm-2 s-1 barrier for the first time, well on the way to achieving the 2010 objective of 1032 cm-2 s-1. This peak luminosity goal requires 800 nominal bunches per beam squeezed to a beta of 3.5 metres. The plan for 2011 is to run the LHC in this configuration over about 10 months, thus achieving the objective of recording one inverse femtobarn of data in total. The machine development period also allowed the TOTEM detectors to be set up with 45...

  7. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn; Hempel, Maria; Henschel, Hans; Karacheban, Olena; Lange, Wolfgang; Lohmann, Wolfgang; Novgorodova, Olga; Penno, Marek; Walsh, Roberval; Dabrowski, Anne; Guthoff, Moritz; Loos, R; Ryjov, Vladimir; Burtowy, Piotr; Lokhovitskiy, Arkady; Odell, Nathaniel; Przyborowski, Dominik; Stickland, David P; Zagozdzinska, Agnieszka

    2014-01-01

    The CMS beam condition monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be discussed, including results from the January 201...

  8. Vertex, Track Reconstruction and Luminosity Monitoring at LHCb

    Science.gov (United States)

    Wang, J.

    The VELO detector plays a key role in the LHCb experiment. It is essential in vertex and track reconstruction. It can also be used to monitor luminosity. A brief description on the track reconstruction algorithm and application are given. A subset of the final VELO detector has been tested in a pion beam at CERN. Some preliminary results are presented.

  9. Low Luminosity Type II Supernovae: Spectroscopic and Photometric Evolution

    CERN Document Server

    Pastorello, A; Turatto, M; Cappellaro, E; Meikle, W P S; Benetti, S; Branch, D; Baron, E; Patat, F; Armstrong, M; Altavilla, G; Salvo, M E; Riello, M

    2004-01-01

    In this paper we present spectroscopic and photometric observations for four core collapse supernovae (SNe), namely SNe 1994N, 1999br, 1999eu and 2001dc. Together with SN 1997D, we show that they form a group of exceptionally low-luminosity events. These SNe have narrow spectral lines (indicating low expansion velocities) and low luminosities at every phase (significantly lower than those of typical core-collapse supernovae). The very low luminosity during the ^{56}Co radioactive decay tail indicates that the mass of ^{56}Ni ejected during the explosion is much smaller (M(Ni) ~ 2-8 x 10^{-3} Mo) than the average (M(Ni) ~ 6-10 x 10^{-2} Mo). Two supernovae of this group (SN 1999br and SN 2001dc) were discovered very close to the explosion epoch, allowing us to determine the lengths of their plateaux (~ 100 days) as well as establishiing the explosion epochs of the other, less-completely observed SNe. It is likely that this group of SNe represent the extreme low-luminosity tail of a single continuous distributi...

  10. The Radio Luminosity Function and Galaxy Evolution of Abell 2256

    Science.gov (United States)

    Forootaninia, Zahra

    2015-05-01

    This thesis presents a study of the radio luminosity function and the evolution of galaxies in the Abell 2256 cluster (z=0.058, richness class 2). Using the NED database and VLA deep data with an rms sensitivity of 18 mu Jy.beam--1, we identified 257 optical galaxies as members of A2256, of which 83 are radio galaxies. Since A2256 is undergoing a cluster-cluster merger, it is a good candidate to study the radio activity of galaxies in the cluster. We calculated the Univariate and Bivariate radio luminosity functions for A2256, and compared the results to studies on other clusters. We also used the SDSS parameter fracDev to roughly classify galaxies as spirals and ellipticals, and investigated the distribution and structure of galaxies in the cluster. We found that most of the radio galaxies in A2256 are faint, and are distributed towards the outskirts of the cluster. On the other hand, almost all very bright radio galaxies are ellipticals which are located at the center of the cluster. We also found there is an excess in the number of radio spiral galaxies in A2256 compared to the number of radio ellipticals, counting down to a radio luminosity of log(luminosity)=20.135 W/Hz..

  11. LINERs as Low-Luminosity Active Galactic Nuclei

    CERN Document Server

    Ho, L C

    1998-01-01

    Many nearby galaxies contain optical signatures of nuclear activity in the form of LINER nuclei. LINERs may be the weakest and most common manifestation of the quasar phenomenon. The physical origin of this class of objects, however, has been ambiguous. I draw upon a number of recent observations to argue that a significant fraction of LINERs are low-luminosity active galactic nuclei.

  12. Vector and Tensor Contributions to the Luminosity Distance

    CERN Document Server

    Di Dio, Enea

    2012-01-01

    We compute the vector and tensor contributions to the luminosity distance fluctuations in first order perturbation theory and we expand them in spherical harmonics. This work presents the formalism with a first application to a stochastic background of primordial gravitational waves.

  13. Direct Oxygen Abundances for Low Luminosity LVL Galaxies

    CERN Document Server

    Berg, Danielle A; Marble, Andrew R; van Zee, Liese; Engelbracht, Charles W; Lee, Janice C; Kennicutt, Robert C; Jr.,; Calzetti, Daniela; Dale, Daniel A; Johnson, Benjamin D

    2012-01-01

    We present MMT spectroscopic observations of HII regions in 42 low luminosity galaxies in the LVL. For 31 galaxies, we measured the temperature sensitive [O III] line at a strength of 4 sigma or greater, and thus determine direct oxygen abundances. Our results provide the first direct estimates of oxygen abundance for 19 galaxies. Oxygen abundances were compared to B-band and 4.5 micron luminosities and stellar masses in order to characterize the luminosity-metallicity (L-Z) and mass-metallicity (M-Z) relationships at low-luminosity. We present and analyze a "Combined Select" sample composed of 38 objects (drawn from our parent sample and the literature) with direct oxygen abundances and reliable distance determinations (TRGB or Ceph). Consistent with previous studies, the B-band and 4.5 micron L-Z relationships were found to be 12+log(O/H)=(6.27+/-0.21)+(-0.11+/-0.01)M_B and 12+log(O/H)=(6.10+/-0.21)+(-0.10+/-0.01)M_[4.5] (sigma=0.15 and 0.14). For this sample, we derive a M-Z relationship of 12+log(O/H)=(5....

  14. A luminosity monitor system for the JETSET experiment at LEAR

    International Nuclear Information System (INIS)

    A luminosity-monitor system for the JETSET experiment at LEAR is described. Four silicon-strip detectors are used as position sensitive devices to monitor the elastic pp-scattering. The design concept, data-acquisition and results of the detector system are presented. On-line monitoring is used to assure the proper operation of the JETSET experiment. (orig.)

  15. Finding and characterising WHIM structures using the luminosity density method

    CERN Document Server

    Nevalainen, J; Tempel, E; Branchini, E; Roncarelli, M; Giocoli, C; Heinamaki, P; Saar, E; Bonamente, M; Einasto, M; Finoguenov, A; Kaastra, J; Lindfors, E; Nurmi, P; Ueda, Y

    2014-01-01

    We have developed a new method to approach the missing baryons problem. We assume that the missing baryons reside in a form of Warm Hot Intergalactic Medium, i.e. the WHIM. Our method consists of (a) detecting the coherent large scale structure in the spatial distribution of galaxies that traces the Cosmic Web and that in hydrodynamical simulations is associated to the WHIM, (b) map its luminosity into a galaxy luminosity density field, (c) use numerical simulations to relate the luminosity density to the density of the WHIM, (d) apply this relation to real data to trace the WHIM using the observed galaxy luminosities in the Sloan Digital Sky Survey and 2dF redshift surveys. In our application we find evidence for the WHIM along the line of sight to the Sculptor Wall, at redshifts consistent with the recently reported X-ray absorption line detections. Our indirect WHIM detection technique complements the standard method based on the detection of characteristic X-ray absorption lines, showing that the galaxy l...

  16. Tevatron Run II luminosity, emittances and collision point size

    Energy Technology Data Exchange (ETDEWEB)

    Jean Slaughter et al.

    2003-06-09

    The authors compare the Tevatron luminosity as measured by the CDF and D0 experiments with that computed from machine characteristics. They also compare the CDF measurements for the size of the interaction region with that predicted by machine parameters. Although these results are still preliminary, they show promise as a useful crosscheck of the instrumentation and our understanding of the Tevatron machine characteristics.

  17. A Single Bremsstrahlung Monitor to Measure Luminosity at LEP

    CERN Multimedia

    2002-01-01

    The luminosity, the beam divergence and the longitudinal polarization can be measured at an interaction point of LEP by dectecting the energy, the angular distribution and the circular polarization of the single bremsstrahlung photons (SB) emitted at very forward angle. The luminosity can be measured by this met than by the conventional method of detecting small angle Bhabha scattering. The bunch to bunch relative luminosity can be monitored at a few per mil level in few minutes. Absolute values of the luminosity and of the polarization can be measured with a precision of the order of 1\\%. \\\\ \\\\ The apparatus to detect SB photons consists of a low Z absorber and of an EM calorimeter made of lead and scintillating fibres. Both the total energy and the space distribution of the SB photons are measured. This apparatus has been designed and built at the Department of Physics and INFN Section of the University of Rome ``La Sapienza''. Later on, together with suitable monocrystal converters, it may be used also for...

  18. Upgraded Fast Beam Conditions Monitor for CMS online luminosity measurement

    CERN Document Server

    Leonard, Jessica Lynn

    2014-01-01

    The CMS beam and radiation monitoring subsystem BCM1F during LHC Run I consisted of 8 individual diamond sensors situated around the beam pipe within the tracker detector volume, for the purpose of fast monitoring of beam background and collision products. Effort is ongoing to develop the use of BCM1F as an online bunch-by-bunch luminosity monitor. BCM1F will be running whenever there is beam in LHC, and its data acquisition is independent from the data acquisition of the CMS detector, hence it delivers luminosity even when CMS is not taking data. To prepare for the expected increase in the LHC luminosity and the change from 50 ns to 25 ns bunch separation, several changes to the system are required, including a higher number of sensors and upgraded electronics. In particular, a new real-time digitizer with large memory was developed and is being integrated into a multi-subsystem framework for luminosity measurement. Current results from Run II preparation will be shown, including results from the January 201...

  19. Cosmic downsizing of powerful radio galaxies to low radio luminosities

    Science.gov (United States)

    Rigby, E. E.; Argyle, J.; Best, P. N.; Rosario, D.; Röttgering, H. J. A.

    2015-09-01

    Aims: At bright radio powers (P1.4 GHz > 1025 W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution persists for sources an order of magnitude fainter than those previously studied, by measuring the steep-spectrum radio luminosity function (RLF) across the range 1024 plane at the lowest radio powers, a new faint radio sample is introduced; it covers an area of 0.8 sq. deg., in the Subaru/XMM-Newton Deep Field, to a 1.4 GHz flux density limit of S1.4 GHz ? 100 ?Jy, with 99% redshift completeness. Results: The modelling results show that the previously seen high-redshift declines in space density persist to P1.4 GHz 1026 W/Hz the redshift of the peak space density increases with luminosity, whilst at lower radio luminosities the position of the peak remains constant within the uncertainties. This cosmic downsizing behaviour is found to be similar to that seen at optical wavelengths for quasars, and is interpreted as representing the transition from radiatively efficient to inefficient accretion modes in the steep-spectrum population. This conclusion is supported by constructing simple models for the space density evolution of these two different radio galaxy classes; these models are able to successfully reproduce the observed variation in peak redshift.

  20. LHC Report: Boost in bunches brings record luminosity

    CERN Multimedia

    2011-01-01

    Having hit a luminosity of around 8.4x1032 cm-2 s-1 with 768 bunches per beam, the LHC went into a 5-day machine development (MD) program on Wednesday 4 May. Operators are now working on increasing the number of particle bunches in the machine towards a 2011 maximum of around 1380 bunches. The team is already hitting major milestones, recording another record-breaking peak luminosity on Monday 23 May.   Former LHC Project Leader Lyn Evans (to the right) and Laurette Ponce, the engineer-in-charge when the recent luminosity record was achieved. The MD periods improve our understanding of the machine, with the aim of increasing its short- and long-term performance. This one also included tests of the machine’s configurations for special physics runs and a future high luminosity LHC. It was an intense program and overall it went very well, with most measurements carried out successfully. Highlights included: commissioning a dedicated machine setup for TOTEM and ALFA; succe...

  1. Connections between the Radio, Optical and Soft X-ray Luminosities for Flat-Spectrum Radio Quasars

    Indian Academy of Sciences (India)

    Zhi-Fu Chen; Cai-Juan Pan; You-Bing Li; Yu-Tao Zhou

    2014-09-01

    We investigate the connections between radio, optical and soft X-ray luminosities with a sample of 538 FSRQs. We find that the radio luminosity is strongly correlated with the optical luminosity, as well as with the soft X-ray luminosity. We also find that the optical luminosity is strongly correlated with the soft X-ray luminosity.

  2. Precision luminosity measurement at LHCb with beam-gas imaging

    International Nuclear Information System (INIS)

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy ?(s)=8 TeV and ?(s)=2.76 TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. Therefore, a new method has been developed using all reconstructed vertices in order to improve the understanding of the vertex resolution. In addition to the overlap integral, the knowledge of the colliding bunch populations is required to measure the luminosity. The determination of the bunch populations relies on LHC instruments to measure the bunch population fractions and the total beam intensity. Studies performed as part of this work resulted in a reduction of the bunch current normalization uncertainty from ±2.7% to ±0.2% and making it possible to achieve precision luminosity measurements at all LHC experiments. Furthermore, information on beam-gas interactions not originating from nominally filled bunches was analyzed to determine the charge fraction not participating in bunch collisions. The knowledge of this fraction is required to correct the total beam intensity. The reference cross-section of pp interactions with at least two tracks in the vertex detector was measured with the beam-gas imaging method. The result is ?Track=60.6±0.9 mb at a center-of-mass energy of ?(s)=8 TeV. The same measurement performed at ?(s)=2.76 TeV results in a cross-section of ?Track=52.7±1.2 mb. The luminosity measurement at ?(s)=8 TeV presented here, with an uncertainty of 1.4%, is to date the most precise luminosity calibration performed at the LHC and at any other bunched-beam proton collider.

  3. Precision luminosity measurement at LHCb with beam-gas imaging

    Energy Technology Data Exchange (ETDEWEB)

    Barschel, Colin

    2014-03-05

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy ?(s)=8 TeV and ?(s)=2.76 TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. Therefore, a new method has been developed using all reconstructed vertices in order to improve the understanding of the vertex resolution. In addition to the overlap integral, the knowledge of the colliding bunch populations is required to measure the luminosity. The determination of the bunch populations relies on LHC instruments to measure the bunch population fractions and the total beam intensity. Studies performed as part of this work resulted in a reduction of the bunch current normalization uncertainty from ±2.7% to ±0.2% and making it possible to achieve precision luminosity measurements at all LHC experiments. Furthermore, information on beam-gas interactions not originating from nominally filled bunches was analyzed to determine the charge fraction not participating in bunch collisions. The knowledge of this fraction is required to correct the total beam intensity. The reference cross-section of pp interactions with at least two tracks in the vertex detector was measured with the beam-gas imaging method. The result is ?{sub Track}=60.6±0.9 mb at a center-of-mass energy of ?(s)=8 TeV. The same measurement performed at ?(s)=2.76 TeV results in a cross-section of ?{sub Track}=52.7±1.2 mb. The luminosity measurement at ?(s)=8 TeV presented here, with an uncertainty of 1.4%, is to date the most precise luminosity calibration performed at the LHC and at any other bunched-beam proton collider.

  4. Status and Outlook for the RHIC Luminosity Upgrade

    Science.gov (United States)

    Bai, Mei

    2010-02-01

    As the world highest energy heavy ion collider, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory has been the center for exploring the universe at its infant stage. The operations of RHIC over the past decade has produced many results. A new state of matter, the quark-gluon plasma which is believed to only have existed right after the birth of the universe, was first observed at RHIC during the collisions of Au ions. The experimental data also revealed that this new state of matter behaves like a perfect fluid. In addition to the heavy ion program, RHIC is also capable to accelerate polarized proton beams to high energy, which allows one to explore the spin structure of polarized protons. Both the heavy ion program and spin physics program require high luminosities at RHIC. Various efforts aimed at increasing the RHIC luminosity of heavy ion and polarized proton collisions, such as NEG coating beam pipes to reduce electron clouds, using intrabeam scattering lattice for heavy ion operations as well as longitudinal stochastic cooling. The average store luminosity of Au collisions at a beam energy of 100 GeV/u has reached 1027cm-2s-1. The average store luminosity of RHIC polarized proton collisions at a beam energy of 100 GeV reached 28x1030cm-2s-1 and 55x1030 cm-2s-1 for the polarized proton collisions at a beam energy 250 GeV. Currently, the luminosity is limited by beam-beam effects for polarized proton collisions and intrabeam scattering for heavy ion collisions. Novel techniques are explored and under development to address these issues. The addition of transverse stochastic cooling will minimize the beam size growth due to intrabeam scattering and increase the heavy ion luminosity lifetime. The technique of using 9MHz cavity to accelerate polarized protons minimizes the electron cloud effect, which can cause emittance blowup. It also helps to preserve the longitudinal emittance and yields shorter bunches. The technique of employing an electron lens to compensate the beam-beam effect is also currently explored at RHIC. This presentation will report the current performance of RHIC as well as the plans for RHIC luminosity upgrades. )

  5. Determination of the absolute luminosity at the LHC

    International Nuclear Information System (INIS)

    The work presented in this thesis significantly contributed to LHC (Large Hadron Collider) start-up. A first luminosity calibration using the Van Der Meer scan method was provided to the particle physics experiments. The anticipated sources of uncertainty were estimated by simulations and analytical approach Measurements confirmed that most of them were small and could be well determined. The main contribution to the overall uncertainty comes from the knowledge of the beam intensities. A resolution of 11% was reached at the very first try. The first observations and a detailed study and characterization of systematic uncertainties indicate that under well controlled and optimized beam conditions a precision of 5% could be reached in future absolute luminosity measurements. Chapter 1 of this thesis is intended as an introduction to general accelerators physics concepts and definitions that will be used in the following chapters. General expressions of the luminosity are derived including complications such as the presence of a crossing angle or the hourglass effect. Chapter 2 focuses on the Van Der Meer method. The principle of the method and implications of the effects introduced in Chapter 1 are discussed. Chapter 3 and 4 give an overview of the CERN accelerator complex focusing on the LHC and its instrumentation. Beam dynamics and optics studies related to the optimization of the collisions and more generally of the interaction regions are shown as well as tracking simulations for the LHC luminosity monitors. Chapter 5 and 6 present the results obtained at the LHC and RHIC during luminosity calibration measurements. A detailed analysis of the systematics uncertainties associated to the measurement and proposals for future improvements are discussed. Chapter 6 also describes more specifically the procedure and implementation of the tools for luminosity optimization and calibration at the LHC as well as the first experience with operation in collision. Finally, in Chapter 7, an alternative method for luminosity calibration is introduced. Dedicated optics are required for this measurement. An overview of the study and performance of these optics is presented

  6. AGN BLR structure, luminosity and mass from combined Reverberation Mapping and Optical Interferometry observations

    CERN Document Server

    Rakshit, Suvendu

    2014-01-01

    Unveiling the structure of the Broad Line Region (BLR) of AGN is critical to understand the quasar phenomenon. Detail study of the geometry and kinematic of these objects can answer the basic questions about the central BH mass, accretion mechanism and rate, growth and evolution history. Observing the response of the BLR clouds to continuum variations, Reverberation Mapping (RM) provides size vs luminosity and mass vs luminosity relations for QSOs and Sy1 AGNs with the goal to use these objects as standard candles and mass tags. However, the RM size can receive different interpretations depending on the assumed geometry and the corresponding mass depends on an unknown geometrical factor as well on the possible confusion between local and global velocity dispersion. From RM alone, the scatter around the mean mass is as large as a factor 3. Though BLRs are expected to be much smaller than the current spatial resolution of large optical interferometers (OI), we show that differential interferometry with AMBER, G...

  7. Star-formation rates, molecular clouds, and the origin of the far-infrared luminosity of isolated and interacting galaxies

    International Nuclear Information System (INIS)

    The CO luminosities of 93 galaxies have been determined and are compared with their IRAS FIR luminosities. Strongly interacting/merging galaxies have L(FIR)/L(CO) substantially higher than that of isolated galaxies or galactic giant molecular clouds (GMCs). Galaxies with tidal tails/bridges are the most extreme type with L(FIR)/L(CO) nine times as high as isolated galaxies. Interactions between close pairs of galaxies do not have much effect on the molecular content and global star-formation rate. If the high ratio L(FIR)/L(CO) in strongly interacting galaxies is due to star formation then the efficiency of this process is higher than that of any galactic GMC. Isolated galaxies, distant pairs, and close pairs have an FIR/CO luminosity ratio which is within a factor of two of galactic GMCs with H II regions. The CO luminosities of FIR-luminous galaxies are among the highest observed for any spiral galaxies. 42 references

  8. Mass-loss rates and luminosity functions of dust-enshrouded AGB stars and red supergiants in the LMC

    CERN Document Server

    Van Loon, J T; De Koter, A; Trams, N R; Waters, L B F M; Zijlstra, A A; Whitelock, P A; Loup, C; Loon, Jacco Th. van; Trams, Norman R.; Zijlstra, Albert A.; Whitelock, Patricia A.; Loup, Cecile

    1999-01-01

    A radiative transfer code is used to model the spectral energy distributions of 57 mass-losing Asymptotic Giant Branch (AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud (LMC) for which ISO spectroscopic and photometric data are available. As a result we derive mass-loss rates and bolometric luminosities. A gap in the luminosity distribution around M_bol = -7.5 mag separates AGB stars from RSGs. The luminosity distributions of optically bright carbon stars, dust-enshrouded carbon stars and dust-enshrouded M-type stars have only little overlap, suggesting that the dust-enshrouded AGB stars are at the very tip of the AGB and will not evolve significantly in luminosity before mass loss ends their AGB evolution. Derived mass-loss rates span a range from Mdot about 10^-7 to 10^-3 M_sun/yr. More luminous and cooler stars are found to reach higher mass-loss rates. The highest mass-loss rates exceed the classical limit set by the momentum of the stellar radiation field, L/c, by a factor of a few due...

  9. The luminosity function at z ? 8 from 97 Y-band dropouts: Inferences about reionization

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Kasper B.; Treu, Tommaso; Kelly, Brandon C. [Department of Physics, University of California, Santa Barbara, CA 93106-9530 (United States); Trenti, Michele [Kavli Institute for Cosmology and Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Bradley, Larry D.; Stiavelli, Massimo [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Oesch, Pascal A. [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States); Holwerda, Benne W. [Leiden Observatory, Leiden University, NL-2300 RA Leiden (Netherlands); Shull, J. Michael, E-mail: kschmidt@physics.ucsb.edu [CASA, Department of Astrophysical and Planetary Science, University of Colorado, Center for Astrophysics and Space Astronomy, 389-UCB, Boulder, CO 80309 (United States)

    2014-05-01

    We present the largest search to date for Y-band dropout galaxies (z ? 8 Lyman break galaxies, LBGs) based on 350 arcmin{sup 2} of Hubble Space Telescope observations in the V, Y, J, and H bands from the Brightest of Reionizing Galaxies (BoRG) survey. In addition to previously published data, the BoRG13 data set presented here includes approximately 50 arcmin{sup 2} of new data and deeper observations of two previous BoRG pointings, from which we present 9 new z ? 8 LBG candidates, bringing the total number of BoRG Y-band dropouts to 38 with 25.5 ? m{sub J} ? 27.6 (AB system). We introduce a new Bayesian formalism for estimating the galaxy luminosity function, which does not require binning (and thus smearing) of the data and includes a likelihood based on the formally correct binomial distribution as opposed to the often-used approximate Poisson distribution. We demonstrate the utility of the new method on a sample of 97 Y-band dropouts that combines the bright BoRG galaxies with the fainter sources published in Bouwens et al. from the Hubble Ultra Deep Field and Early Release Science programs. We show that the z ? 8 luminosity function is well described by a Schechter function over its full dynamic range with a characteristic magnitude M{sup ?}=?20.15{sub ?0.38}{sup +0.29}, a faint-end slope of ?=?1.87{sub ?0.26}{sup +0.26}, and a number density of log{sub 10}??{sup ?}[Mpc{sup ?3}]=?3.24{sub ?0.24}{sup +0.25}. Integrated down to M = –17.7, this luminosity function yields a luminosity density log{sub 10}??[erg s{sup ?1} Hz{sup ?1} Mpc{sup ?3}]=25.52{sub ?0.05}{sup +0.05}. Our luminosity function analysis is consistent with previously published determinations within 1?. The error analysis suggests that uncertainties on the faint-end slope are still too large to draw a firm conclusion about its evolution with redshift. We use our statistical framework to discuss the implication of our study for the physics of reionization. By assuming theoretically motivated priors on the clumping factor and the photon escape fraction we show that the UV luminosity density from galaxy samples down to M = –17.7 can ionize only 10%-50% of the neutral hydrogen at z ? 8. Full reionization would require extending the luminosity function down to M = –15. The data are consistent with a substantial fraction of neutral hydrogen at z > 7, in agreement with recent suggestions based on deep spectroscopy of z ? 8 LBGs.

  10. The FCC-ee design study: luminosity and beam polarization

    CERN Document Server

    Koratzinos, M

    2015-01-01

    The FCC-ee accelerator is considered within the FCC design study as a possible first step towards the ultimate goal of a 100 TeV hadron collider. It is a high luminosity e+e- storage ring collider, designed to cover energies of around 90, 160, 240 and 350GeV ECM (for the Z peak, the WW threshold, the ZH and ttbar cross-section maxima respectively) leading to different operating modes. We report on the current status of the design study, on the most promising concepts and relevant challenges. The expected luminosity performance at all energies, and first studies on transverse polarization for beam energy calibrations will be presented.

  11. Silicon Sensors for Trackers at High-Luminosity Environment

    CERN Document Server

    Peltola, Timo

    2014-01-01

    The planned upgrade of the LHC accelerator at CERN, namely the high luminosity (HL) phase of the LHC (HL-LHC foreseen for 2023), will result in a more intense radiation environment than the present tracking system was designed for. The required upgrade of the all-silicon central trackers at the ALICE, ATLAS, CMS and LHCb experiments will include higher granularity and radiation hard sensors. The radiation hardness of the new sensors must be roughly an order of magnitude higher than the one of LHC detectors. To address this, a massive R&D program is underway within the CERN RD50 collaboration "Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders" to develop silicon sensors with sufficient radiation tolerance. Research topics include the improvement of the intrinsic radiation tolerance of the sensor material and novel detector designs with benefits like reduced trapping probability (thinned and 3D sensors), maximized sensitive area (active edge sensors) and enhanced charge ...

  12. Fast Polycrystalline-CdTe Detectors for LHC Luminosity Measurements

    CERN Document Server

    Rossa, E; Placidi, Massimo; Schmickler, Hermann; Brambilla, A; Mongellaz, F; Verger, L; Cindro, V; Mikuz, M; Moritz, P

    2002-01-01

    Beam diagnostics in future high-energy accelerators will require long lived instrumentation in highly hostile radiation environments. A research program aiming at individuating new solutions and testing them under extreme operational conditions has been launched at CERN in the framework of developments for the LHC instrumentation. Its outcome might be used in future accelerator projects, in industry or in physics applications. The detectors which will be adopted for the LHC luminosity monitoring and optimization will be installed close to or inside copper absorbers specifically designed for radiation protection of the accelerator magnetic elements in the interaction regions. These detectors will have to withstand extreme radiation levels and their long-term operation has to be assured without requiring human intervention. Polycrystalline-CdTe detectors have demonstrated their radiation hardness against extreme doses of X-ray exposure in the LEP collider and are considered as good candidates for LHC luminosity...

  13. L1 track triggering at CMS for High Luminosity LHC

    International Nuclear Information System (INIS)

    The High Luminosity LHC (HL-LHC) is expected to deliver luminosities of 5 × 1034 c -2 -1, with an average number of overlapping proton-proton collisions per bunch crossing (pileup) of about 140. These extreme pileup conditions place stringent requirements on the experiments' trigger systems to cope with the resulting event rates. For the CMS experiment, a key component of the detector upgrade for the HL-LHC is a track-trigger system which would identify tracks with transverse momentum above 2 GeV already at the first-level (L1) trigger. Here, a proposal for implementing L1 tracking using ''tracklets'' is presented. The expected performance of the L1 tracking from simulation studies and the use of L1 tracks to define trigger objects are discussed

  14. The K Band Luminosity Function of High Redshift Clusters

    CERN Document Server

    Ellis, S C

    2003-01-01

    K band observations of the galaxy populations of three high redshift (z=0.8-1.0), X-ray selected, massive clusters are presented. The observations reach a depth of K = 21.5, corresponding to K*+3.5 mag. The evolution of the galaxy properties are discussed in terms of their K band luminosity functions and the K band Hubble diagram of brightest cluster galaxies. The bulk of the galaxies, as characterised by the parameter K* from the Schechter (1976) function, are found to be consistent with passive evolution with a redshift of formation of z_f = 1.5-2. This is in agreement with observations of other high redshift clusters, but in disagreement with field galaxies at similar redshifts. The shape of the luminosity function at high redshift, after correcting for passive evolution, is not significantly different from that of the Coma cluster, again consistent with passive evolution.

  15. SLHC, the High-Luminosity Upgrade (public event)

    CERN Document Server

    CERN. Geneva

    2010-01-01

    In the morning of June 23rd a public event is organised in CERN's Council Chamber with the aim of providing the particle physics community with up-to-date information about the strategy for the LHC luminosity upgrade and to describe the current status of preparation work. The presentations will provide an overview of the various accelerator sub-projects, the LHC physics prospects and the upgrade plans of ATLAS and CMS. This event is organised in the framework of the SLHC-PP project, which receives funding from the European Commission for the preparatory phase of the LHC High Luminosity Upgrade project. Informing the public is among the objectives of this EU-funded project. A simultaneous transmission of this meeting will be broadcast, available at the following address: http://webcast.cern.ch/

  16. High luminosity electron-hadron collider eRHIC

    International Nuclear Information System (INIS)

    We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 1034 cm-2 s-1 can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R and D such as the high-current polarized electron source, the coherent electron cooling, ERL test facility and the compact magnets for recirculation passes. A natural staging scenario of step-by-step increases of the electron beam energy by building-up of eRHIC's SRF linacs is presented.

  17. The Luminosity Function of Galaxies in the Hercules Cluster

    CERN Document Server

    Sánchez-Janssen, R; Muñoz-Tunón, C; López-Aguerri, J A; Vílchez, J M

    2004-01-01

    We have imaged $\\sim$ 1 deg$^{2}$ in the V-band in the direction of the Hercules Cluster (Abell 2151). The data are used to compute for the first time the luminosity function (LF) of galaxies in the cluster down to the dwarf regime (M$_{lim}$ $\\sim$ -13.85). The global LF is well described by a Schechter function (\\cite{schechter76}) with best-fit parameters $\\alpha$ = -1.30 $\\pm$ 0.06 and M$_V

  18. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    Science.gov (United States)

    Loveday, J.; Norberg, P.; Baldry, I. K.; Driver, S. P.; Hopkins, A. M.; Peacock, J. A.; Bamford, S. P.; Liske, J.; Bland-Hawthorn, J.; Brough, S.; Brown, M. J. I.; Cameron, E.; Conselice, C. J.; Croom, S. M.; Frenk, C. S.; Gunawardhana, M.; Hill, D. T.; Jones, D. H.; Kelvin, L. S.; Kuijken, K.; Nichol, R. C.; Parkinson, H. R.; Phillipps, S.; Pimbblet, K. A.; Popescu, C. C.; Prescott, M.; Robotham, A. S. G.; Sharp, R. G.; Sutherland, W. J.; Taylor, E. N.; Thomas, D.; Tuffs, R. J.; van Kampen, E.; Wijesinghe, D.

    2012-02-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z riz bands, and by blue galaxies in u and g.

  19. An absolute luminosity monitor for the LHCb experiment

    Science.gov (United States)

    Laštovi?ka, Tomáš

    2007-12-01

    A novel method of measuring the absolute luminosity at colliding beam experiments is proposed. The method is based on a measurement of beam-gas interaction vertices to determine beam shapes and overlaps. This method can be applied at the LHCb experiment without the need for any modifications of existing sub-detectors and it is entirely based on the LHCb Vertex Locator (VELO) silicon tracker.

  20. LHC abort gap cleaning studies during luminosity operation

    CERN Document Server

    Bartmann, W; Bracco, C; Bravin, E; Goddard, B; Höfle, W; Jacquet, D; Jeff, A; Kain, V; Meddahi, M; Roncarolo, F; Uythoven, J; Valuch, D; Gianfelice-Wendt, E

    2012-01-01

    The presence of significant intensities of un-bunched beam is a potentially serious issue in the LHC. Procedures using damper kickers for cleaning both the Abort Gap (AG) and the buckets targeted for injection, are currently in operation at flat bottom. Recent observations of relatively high population of the AG during physics runs brought up the need for AG cleaning during luminosity operation. In this paper the results of experimental studies performed in October 2011 are presented.

  1. The Luminosities and Diameters of Mira Variables from Hipparcos Parallaxes

    OpenAIRE

    P. A. Whitelock; van Leeuwen, F.; Feast, M. W.

    1997-01-01

    Hipparcos trigonometrical parallaxes of Mira-type variables have been combined with ground-based angular diameter measurements to derive linear diameters. Of eight stars with ground-based data, six have diameters indicating overtone pulsation whilst two, both with periods over 400 day, are pulsating in the fundamental. Hipparcos parallaxes of 11 Miras have been combined with extensive infrared photometry to determine the zero-point of the Mira period-luminosity relation. ...

  2. Robust Constraint of Luminosity Function Evolution Through MCMC Sampling

    OpenAIRE

    Kurinsky, Noah; Sajina, Anna

    2014-01-01

    We present a new galaxy survey simulation package, which combines the power of Markov Chain Monte Carlo (MCMC) sampling with a robust and adaptable model of galaxy evolution. The aim of this code is to aid in the characterization and study of new and existing galaxy surveys. In this paper we briefly describe the MCMC implementation and the survey simulation methodology and associated tools. A test case of this full suite was to constrain the evolution of the IR Luminosity Fu...

  3. Dynamic Aperture Studies for the LHC High Luminosity Lattice

    CERN Document Server

    De Maria, R; Giovannozzi, Massimo; Mcintosh, Eric; Cai, Y; Nosochkov, Y; Wang, M H

    2015-01-01

    Since quite some time, dynamic aperture studies have been undertaken with the aim of specifying the required field quality of the new magnets that will be installed in the LHC ring in the framework of the high-luminosity upgrade. In this paper the latest results concerning the specification work will be presented, taking into account both injection and collision energies and the field quality contribution from all the magnets in the newly designed interaction regions.

  4. CP stars: Photometric calibrations of luminosity using Hipparcos data

    OpenAIRE

    Figueras, F.; Luri, X.; Gomez, A. E.; Torra, J.; Jordi, C.; Mennessier, M. O.; Domingo, A.; Masana, E.; Grenier, S.; Blasi, F.

    1998-01-01

    The application of the Stromgren photometric luminosity calibrations to different types of CP stars is reexamined in the light of the new Hipparcos data. A first attempt is made to use the LM statistical parallax method (Luri et al., 1996) -- based on the maximum likelihood principle -- to obtain a calibration of the absolute magnitude as a function of two Stromgren colour indices, thus reflecting effective temperature and evolution. Its application to a sample of Si stars a...

  5. HI in Low-Luminosity Early-Type Galaxies

    OpenAIRE

    Oosterloo, Tom; Morganti, Raffaella; Sadler, Elaine

    1998-01-01

    We discuss the properties of the HI in low-luminosity early-type galaxies. The morphology of the HI is more regular than that of the HI in many more-luminous early-type galaxies. The HI is always distributed in a disk and is more centrally concentrated. The central HI surface densities are higher than in luminous early-type galaxies and are high enough for star formation to occur.

  6. When teaching: Out with magnitudes, in with monochromatic luminosities!

    OpenAIRE

    Verbunt, Frank

    2008-01-01

    The goal of this document is to illustrate that teaching the concepts of magnitudes is a needless complication in introductory astronomy courses, and that use of monochromatic luminosities, rather than arbitrarily defined magnitudes, leads to a large gain in transparency. This illustration is done through three examples: the Hertzsprung-Russell diagram, the cosmic distance ladder, and interstellar reddening. I provide conversion equations from the magnitude-based to the lumi...

  7. Correlation Analysis of Multi-Wavelength Luminosity of Fermi Blazars

    Indian Academy of Sciences (India)

    Xiongwei Bi; Wanquan He; Jiajin Tian; Zhimei Ding; Shuping Ge

    2014-09-01

    We have studied the correlations between luminosities (R, O, X, ) in radio, optical, X-ray and -ray wave bands for Fermi blazars, and found that there are significant correlations between R and , X and and O and for blazars, BL Lacs and FSRQs, but no correlation between and O for BL Lacs. These results suggest that for Fermi blazars, the high energy -ray emission can be related with radio, X-ray and optical emissions.

  8. Electron-cloud effects in high-luminosity colliders

    International Nuclear Information System (INIS)

    Electron-cloud instabilities are expected to be important in most high-luminosity double-ring colliders. In this report, the author describes a few parameter regimes and some critical parameter dependences of this type of instability, and illustrate these with simulation results for the PEP-II and KEK B factories, the LHC, the VLHC, and DAPHNE. In addition, the author studies the possibility and the potential impact of an electron cloud in the interaction region

  9. Designing the ATLAS trigger menu for high luminosities

    International Nuclear Information System (INIS)

    The LHC has a bunch-crossing rate of 20 MHz whereas the ATLAS detector has an average recording rate of about 400 Hz. To reduce the rate of events but still maintain a high efficiency for selecting interesting events needed by ATLAS physics analyses, a three-level trigger system is used in ATLAS. Events are selected based on the Trigger Menu, the definitions of the physics signatures the experiment triggers on. In the 2012 data taking since April, approximately 700 chains are used online. The menu must reflect not only the physics goals of the collaboration but also take into consideration the LHC luminosity and the strict DAQ limitations. An overview of the design, the validation and the performance of the trigger menu for the 2011 data-taking is given. During 2011, the menu had to evolve as the luminosity increase from below 2×1033 cm?2s?1 to almost 5×1033 cm?2s?1. Re-designing the menu for the up-coming high luminosity of around 1034 cm?2s?1 and large number of collision events that take place per each bunch crossing (pile-up) of around 35 interactions per bunch crossing at ?s = 8 TeV is described. Initial performance in the 2012 data-taking is also reported.

  10. Designing the ATLAS trigger menu for high luminosities

    Science.gov (United States)

    Nakahama, Yu

    2012-12-01

    The LHC has a bunch-crossing rate of 20 MHz whereas the ATLAS detector has an average recording rate of about 400 Hz. To reduce the rate of events but still maintain a high efficiency for selecting interesting events needed by ATLAS physics analyses, a three-level trigger system is used in ATLAS. Events are selected based on the Trigger Menu, the definitions of the physics signatures the experiment triggers on. In the 2012 data taking since April, approximately 700 chains are used online. The menu must reflect not only the physics goals of the collaboration but also take into consideration the LHC luminosity and the strict DAQ limitations. An overview of the design, the validation and the performance of the trigger menu for the 2011 data-taking is given. During 2011, the menu had to evolve as the luminosity increase from below 2×1033 cm-2s-1 to almost 5×1033 cm-2s-1. Re-designing the menu for the up-coming high luminosity of around 1034 cm-2s-1 and large number of collision events that take place per each bunch crossing (pile-up) of around 35 interactions per bunch crossing at ?s = 8 TeV is described. Initial performance in the 2012 data-taking is also reported.

  11. Cosmological simulations of black hole growth: AGN luminosities and downsizing

    CERN Document Server

    Michaela, Hirschmann; Alexandro, Saro; Stefano, Borgani; Andreas, Burkert

    2013-01-01

    In this study, we present a detailed, statistical analysis of black hole (BH) growth and the evolution of active galactic nuclei (AGN) using cosmological hydrodynamic simulations run down to z=0. The simulations self-consistently follow radiative cooling, star formation, metal enrichment, BH growth and associated feedback processes from both supernovae typeII/Ia and AGN. We consider two simulation runs, one with a large co-moving volume of (128 Mpc/h)^3 and one with a smaller volume of (48 Mpc/h)^3 but with a higher mass resolution. Consistently with previous results, our simulations are in reasonably good agreement with BH properties of the local Universe. Furthermore, they can successfully reproduce the evolution of the bolometric AGN luminosity function for both the low- and the high-luminosity end up to z=2.5. The smaller but higher resolution run can match the observational data of the low bolometric luminosity end even up to z=4-5. We also perform a direct comparison with the observed soft and hard X-ra...

  12. Precision luminosity measurement at LHCb with beam-gas imaging

    CERN Document Server

    Barschel, Colin

    The luminosity is the physical quantity which relates the cross-section to the production rate in collider experiments. The cross-section being the particle physics observable of interest, a precise determination of the luminosity is required. This work presents the absolute luminosity calibration results performed at the Large Hadron Collider beauty (LHCb) experiment at CERN using a novel method based on beam-gas interactions with data acquired at a center of mass energy $\\sqrt{s}=8$ TeV and $\\sqrt{s}=2.76$ TeV. Reconstructed beam-gas interaction vertices in LHCb are used to measure the beam profiles, thus making it possible to determine the beams overlap integral. An important element of this work was to install and use a neon gas injection system to increase the beam-gas interaction rate. The precision reached with the beam-gas imaging method relies on the two-dimensional beam shape determination developed in this work. For such precision, the interaction vertex resolution is an important ingredient. There...

  13. The rate and luminosity function of Short GRBs

    CERN Document Server

    Piran, T; Piran, Tsvi; Guetta, Dafne

    2006-01-01

    We compare the luminosity function and rate inferred from the BATSE short hard bursts (SHBs) peak flux distribution with the redshift and luminosity distributions of SHBs observed by Swift/HETE II. The Swift/HETE II SHB sample is incompatible with SHB population that follows the star formation rate. However, it is compatible with a distribution of delay times after the SFR. This would be the case if SHBs are associated with binary neutron star mergers. The implied SHB rates that we find range from \\sim 8 to \\sim 30h_{70}^3 Gpc^{-3}yr^{-1}. This rate is a much higher than what was previously estimated and it is comparable to the rate of neutron star mergers estimated from statistics of binary pulsars. If GRBs are produced in mergers the implied rate practically guarantees detection by LIGO II and possibly even by LIGO I, if we are lucky. Our analysis, which is based on observed short hard burst is limited to bursts with luminosities above 10^{49}erg/sec. Weaker bursts may exist but if so they are hardly detect...

  14. MASS AND LUMINOSITY EVOLUTION OF YOUNG STELLAR OBJECTS

    International Nuclear Information System (INIS)

    A model of protostar mass and luminosity evolution in clusters gives new estimates of cluster age, protostar birthrate, accretion rate, and mean accretion time. The model assumes constant protostar birthrate, core-clump accretion, and equally likely accretion stopping. Its parameters are set to reproduce the initial mass function and to match protostar luminosity distributions in nearby star-forming regions. It obtains cluster ages and birthrates from the observed numbers of protostars and pre-main sequence (PMS) stars, and from the modal value of the protostar luminosity. In 31 embedded clusters and complexes, the global cluster age is 1-3 Myr, matching available estimates based on optical spectroscopy (OS) and evolutionary tracks. This method of age estimation is simpler than OS and is more useful for young embedded clusters where optical spectroscopy is not possible. In the youngest clusters, the protostar fraction decreases outward from the densest gas, indicating that the local star-forming age increases outward from a few 0.1 Myr in small protostar-dominated zones to a few Myr in large PMS-dominated zones.

  15. MASS AND LUMINOSITY EVOLUTION OF YOUNG STELLAR OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    Myers, Philip C., E-mail: pmyers@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2012-06-10

    A model of protostar mass and luminosity evolution in clusters gives new estimates of cluster age, protostar birthrate, accretion rate, and mean accretion time. The model assumes constant protostar birthrate, core-clump accretion, and equally likely accretion stopping. Its parameters are set to reproduce the initial mass function and to match protostar luminosity distributions in nearby star-forming regions. It obtains cluster ages and birthrates from the observed numbers of protostars and pre-main sequence (PMS) stars, and from the modal value of the protostar luminosity. In 31 embedded clusters and complexes, the global cluster age is 1-3 Myr, matching available estimates based on optical spectroscopy (OS) and evolutionary tracks. This method of age estimation is simpler than OS and is more useful for young embedded clusters where optical spectroscopy is not possible. In the youngest clusters, the protostar fraction decreases outward from the densest gas, indicating that the local star-forming age increases outward from a few 0.1 Myr in small protostar-dominated zones to a few Myr in large PMS-dominated zones.

  16. An ionization chamber shower detector for the LHC luminosity monitor

    CERN Document Server

    Beche, J F; Datte, P S; Haguenauer, Maurice; Manfredi, P F; Millaud, J E; Placidi, Massimo; Ratti, L; Re, V; Riot, V J; Schmickler, Hermann; Speziali, V; Turner, W C

    2000-01-01

    The front IR quadrupole absorbers (TAS) and the IR neutral particle absorbers (TAN) in the high luminosity insertions of the Large Hadron Collider (LHC) each absorb approximately 1.8 TeV of forward collision products on average per pp interaction (~235 W at design luminosity 10/sup 34/ cm/sup -2/ s/sup -1/). This secondary particle flux can be exploited to provide a useful storage ring operations tool for optimization of luminosity. A novel segmented, multi-gap, pressurized gas ionization chamber is being developed for sampling the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The system design choices have been strongly influenced by optimization of signal to noise ratio and by the very high radiation environment. The ionization chambers are instrumented with low noise, fast, pulse shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. Data on each bunch are to be separately accumulated over multiple bunch crossings until the desire...

  17. An analytic method to compute star cluster luminosity statistics

    Science.gov (United States)

    da Silva, Robert L.; Krumholz, Mark R.; Fumagalli, Michele; Fall, S. Michael

    2014-03-01

    The luminosity distribution of the brightest star clusters in a population of galaxies encodes critical pieces of information about how clusters form, evolve and disperse, and whether and how these processes depend on the large-scale galactic environment. However, extracting constraints on models from these data is challenging, in part because comparisons between theory and observation have traditionally required computationally intensive Monte Carlo methods to generate mock data that can be compared to observations. We introduce a new method that circumvents this limitation by allowing analytic computation of cluster order statistics, i.e. the luminosity distribution of the Nth most luminous cluster in a population. Our method is flexible and requires few assumptions, allowing for parametrized variations in the initial cluster mass function and its upper and lower cutoffs, variations in the cluster age distribution, stellar evolution and dust extinction, as well as observational uncertainties in both the properties of star clusters and their underlying host galaxies. The method is fast enough to make it feasible for the first time to use Markov chain Monte Carlo methods to search parameter space to find best-fitting values for the parameters describing cluster formation and disruption, and to obtain rigorous confidence intervals on the inferred values. We implement our method in a software package called the Cluster Luminosity Order-Statistic Code, which we have made publicly available.

  18. Luminosity Functions of Young Clusters: Modeling the Substellar Mass Regime

    CERN Document Server

    Allen, P R; Körner, D W; Reid, I N

    2003-01-01

    We predict near-infrared luminosity functions of young (5 Myr to 1 Gyr) star clusters by combining evolutionary models of very low-mass ($1 M_J$ to $0.15 M_{odot}$) dwarfs with empirical bolometric corrections. We identify several characteristic features in our results. These can be attributed to three causes: (1) deuterium burning in the most massive substellar objects; (2) methane absorption in bodies with $T_{eff}$ less than 1300 K, the temperature of the L/T transition; and (3) the formation of dust clouds and the rainout of dust at roughly the same effective temperature as methane formation. Accurate reconstruction of the substellar mass function from luminosity function observations requires that these phenomena are taken into account. At present, few observational studies extend to sufficient sensitivities to allow detection of these effects. However, the luminosity function of the young open cluster IC 2391 shows a clear peak at $M_I sim 14$ which we attribute to the result of deuterium burning in sub...

  19. Beam dynamics studies to develop LHC luminosity model

    CERN Document Server

    Campogiani, Giovanna; Papaphilippou, Ioannis

    The thesis project aims at studying the different physical processes that are impacting luminosity, one of the key figures of merit of a collider operation. In particular the project focuses on extracting the most relevant parameters for the high-energy part of the model, which is mostly dominated by the beam-beam effect. LHC luminosity is degraded by parasitic collisions that reduce the beam lifetime and the particles stability in the collider. This instability is due to the non-linear effects of one beam electromagnetic field on another in the interaction region. Such parasitic encounters can be as many as 16 per interaction region, piling up to around 180 000 per second. Our goal is to study the evolution of charge density distribution in the beam, by tracking particles through a symplectic integrator that includes the beam-beam effect. In particular we want to obtain data on the halo particles, which are more sensible to instability, to better characterise the beam lifetime and monitor the luminosity evol...

  20. The Black Hole Mass - Galaxy Luminosity Relationship for SDSS Quasars

    CERN Document Server

    Salviander, S; Bonning, E W

    2014-01-01

    We investigate the relationship between the mass of the central supermassive black hole, M_bh, and the host galaxy luminosity, L_gal, in a sample of quasars from the Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7). We use composite quasar spectra binned by black hole mass and redshift to assess galaxy features that would otherwise be overwhelmed by noise in individual spectra. The black hole mass is calculated using the photoionization method, and the host galaxy luminosity is inferred from the depth of the Ca II H + K features in the composite spectra. We evaluate the evolution in the M_bh - L_gal relationship by examining the redshift dependence of Delta log M_bh, the offset in black hole mass from the local black hole - bulge relationship. There is little systematic trend in Delta log M_bh out to z = 0.8. Using the width of the [O III] emission line as a proxy for the stellar velocity dispersion, sigma_*, we find agreement of our derived host luminosities with the locally-observed Faber-Jackson relati...

  1. A SYSTEMATIC SEARCH FOR MOLECULAR OUTFLOWS TOWARD CANDIDATE LOW-LUMINOSITY PROTOSTARS AND VERY LOW LUMINOSITY OBJECTS

    International Nuclear Information System (INIS)

    We present a systematic single-dish search for molecular outflows toward a sample of nine candidate low-luminosity protostars and 30 candidate very low luminosity objects (VeLLOs; Lint ? 0.1 L?). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D 12CO and 13CO J = 2 ? 1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30'' resolution. Using five-point grid maps, we identify five new potential outflow candidates and make on-the-fly maps of the regions surrounding sources in the dense cores B59, L1148, L1228, and L1165. Of these new outflow candidates, only the map of B59 shows a candidate blue outflow lobe associated with a source in our survey. We also present larger and more sensitive maps of the previously detected L673-7 and the L1251-A-IRS4 outflows and analyze their properties in comparison to other outflows from VeLLOs. The accretion luminosities derived from the outflow properties of the VeLLOs with detected CO outflows are higher than the observed internal luminosity of the protostars, indicating that these sources likely had higher accretion rates in the past. The known L1251-A-IRS3 outflow is detected but not re-mapped. We do not detect clear, unconfused signatures of red and blue molecular wings toward the other 31 sources in the survey indicating that large-scale, distinct outflows are rare toward this sample of candidate protostars. Several potential outflows are confused with the kinematic structure in the surrounding core and cloud. Interferometric imaging is needed to disentangle large-scale molecular cloud kinematics from these potentially weak protostellar outflows.

  2. The X-ray luminosity function of galaxies in the Coma cluster

    CERN Document Server

    Finoguenov, A; Henry, J P; Gavazzi, G; Iglesias-Páramo, J; Boselli, A

    2004-01-01

    The XMM-Newton survey of the Coma cluster of galaxies covers an area of 1.86 square degrees with a mosaic of 16 pointings and has a total useful integration time of 400 ksec. Detected X-ray sources with extent less than 10" were correlated with cataloged galaxies in the Coma cluster region. The redshift information, which is abundant in this region of the sky, allowed us to separate cluster members from background and foreground galaxies. For the background sources, we recover a typical LogN-LogS in the flux range 1.e-15 - 1.e-13 ergs/s/cm^2 in the 0.5-2.0 keV band. The X-ray emission from the cluster galaxies exhibits X-ray colors typical of thermal emission. The luminosities of Coma galaxies lie in the 1.e39-1.e41 ergs/s interval in the 0.5-2.0 keV band. The luminosity function of Coma galaxies reveals that their X-ray activity is suppressed with respect to the field by a factor of 5.6, indicating a lower level of X-ray emission for a given stellar mass.

  3. Infrared Luminosities and Dust Properties of z ~ 2 Dust-Obscured Galaxies

    CERN Document Server

    Bussmann, R S; Borys, C; Desai, V; Jannuzi, B T; Le Floc'h, E; Melbourne, J; Sheth, K; Soifer, B T

    2009-01-01

    We present SHARC-II 350um imaging of twelve 24um-bright (F_24um > 0.8 mJy) Dust-Obscured Galaxies (DOGs) and CARMA 1mm imaging of a subset of 2 DOGs, all selected from the Bootes field of the NOAO Deep Wide-Field Survey. Detections of 4 DOGs at 350um imply IR luminosities which are consistent within a factor of 2 of expectations based on a warm dust spectral energy distribution (SED) scaled to the observed 24um flux density. The 350um upper limits for the 8 non-detected DOGs are consistent with both Mrk231 and M82 (warm dust SEDs), but exclude cold dust (Arp220) SEDs. The two DOGs targeted at 1mm were not detected in our CARMA observations, placing strong constraints on the dust temperature: T_dust > 35-60 K. Assuming these dust properties apply to the entire sample, we find dust masses of ~3x10^8 M_sun. In comparison to other dusty z ~ 2 galaxy populations such as sub-millimeter galaxies (SMGs) and other Spitzer-selected high-redshift sources, this sample of DOGs has higher IR luminosities (2x10^13 L_sun vs....

  4. A proposal to upgrade the ATLAS RPC system for the High Luminosity LHC

    CERN Document Server

    ATLAS Collaboration; The ATLAS collaboration

    2015-01-01

    The architecture of the present trigger system in the ATLAS Muon Barrel was designed according to a reference luminosity of 10^34 cm-2 s-1 with a safety factor of 5, with respect to the simulated background rates, now confirmed by LHC Run-1 data. HL-LHC will provide a luminosity 5 times higher and an order of magnitude higher background. As a result, the performance demand increases, while the detector being susceptible to ageing effects. Moreover, the present muon trigger acceptance in the barrel is just above 70%, due to the presence of the barrel toroid structures. This scenario induced the ATLAS muon Collaboration to propose an appropriate upgrade plan, involving both detector and trigger-readout electronics, to guarantee the performance required by the physics program for the 20 years scheduled. This consists in installing a layer of new generation RPCs in the inner barrel, to increase the redundancy, the selectivity, and provide almost full acceptance. The first 10% of the system, corresponding to the e...

  5. Double galaxies, their radial velocity measurement errors and mean mass-to-luminosity ratio

    Energy Technology Data Exchange (ETDEWEB)

    Karachentsev, I.D. (AN SSSR, Nizhnij Arkhyz. Spetsial' naya Astrofizicheskaya Observatoriya)

    1983-02-01

    New radial velocity measurements are presented for 44 pairs of galaxies from the Catalogue of isolated pairs of galaxies of the northern hemisphere by Karachentsev (1972), which have not been drawn in a previous spectral survey. Using the data for 75 galaxies, common for our Catalogue and the sample by White et al. (1982), the absolute errors of radial velocity determinations for galaxies observed with the 6-m telescope are estimated. It is shown that the ratio of the external (absolute) error of velocity measurement to the inner one, k=sigmasub(e)/sigmasub(i), changes from 1.0 to 2.1 while passing from strong emission line galaxies to objects with absorption spectra. As applied to component differential velocities the k factor appears to be smaller than for individual velocities of galaxies. Using the method of variation of sample moments of an orbital mass-to-luminosity ratio as a function of k, an estimate of the mean value k=1.4 is obtained. The mean mass-to-luminosity ratio is (7.6+-0.9) fsub(Sun) for 490 pairs of galaxies.

  6. Double galaxies: redshift measurements, error analysis, and mean mass/luminosity ratio

    Energy Technology Data Exchange (ETDEWEB)

    Karachentsev, I.D.

    1983-01-01

    New radial-velocity measurements are presented for 44 double systems drawn from the author's Catalog of Isolated Pairs of Galaxies and not covered by previous spectroscopic surveys. The absolute errors in the redshifts measured on the 6-m telescope spectrograms are estimated by comparison of data for 75 galaxies common to the Catalog and the sample of White et al. The ratio k = sigma/sub e//sigma/sub i/ of the external (absolute) and internal errors in the measured redshift increases from 1.0 to 2.1 as one passes from galaxies with strong emission lines to absorption-line objects. The factor k is smaller for the redshift differential between pair components than for individual redshift measurements. From the k-dependence of the sample moments of the orbital-mass/luminosity ratio, an overall average k = 1.4 is deduced, yielding for 490 pairs a mean mass/luminosity ratio f = (7.6 +- 0.9)f/sub sun/.

  7. LUMINOSITY FUNCTIONS OF TYPE Ia SUPERNOVAE AND THEIR HOST GALAXIES FROM THE SLOAN DIGITAL SKY SURVEY

    International Nuclear Information System (INIS)

    The sample of 137 low-redshift type Ia supernovae (SNe Ia) with 0.05 ? z ? 0.3 obtained from the Sloan Digital Sky Survey (SDSS)-II supernova survey for the southern equatorial stripe of 300 deg2 is used to derive the luminosity functions (LFs) of SNe Ia and of their host galaxies in the g, r, i passbands. We show that the LF of SNe Ia host galaxies matches well with that of galaxies in the general field, suggesting that the occurrence of SNe Ia does not favor a particular type of galaxy but is predominantly proportional to the luminosity of galaxies. The evidence is weak that the SNe rate varies with the color of host galaxies. The only evidence that points to possible correlation between the SN rate and star formation activity is that the SN rate in late-type galaxies is higher than that in early-type galaxies by 31% ± 35%. In our low-redshift sample, the component of type Ia SN rate that is proportional to star formation activity is not evident in the integrated SN rate, while our observation is compatible with the current two-component models. The sample contains eight SNe Ia whose host galaxies were not identified, but it is shown that their occurrence is consistent with them occurring in low-luminous galaxies beyond the survey. The LF of SNe Ia is approximately Gaussian with the full width at half-maximum being a factor of ? = 0.24 mag or 1.67 in luminosity. The Gaussian distribution becomes tighter if the ratio of extinction to reddening, RV , is lower than the characteristic value for the Milky Way and if luminosity is corrected for the light-curve shape. The average color excess is ?0.07 mag, which is significantly smaller than reddening expected for field galaxies. This color excess does not vary with the distance of the SNe from the center of the host galaxy to 15 kpc. This suggests that the major part of the color excess appears to be either intrinsic or reddening that arises in the immediate environment of SNe, rather than interstellar reddening in host galaxies, and most of SNe Ia take place in a relatively dust-free environment.

  8. Data acquisition system and results for the ALEPH very forward luminosity monitor at LEP

    International Nuclear Information System (INIS)

    The data acquisition system of the very forward luminosity monitor for the ALEPH detector at LEP is described. The data analysis performed to obtain the luminosity measurement is also presented. This monitor provides the instantaneous luminosity with good statistical precision and is used for veryfying the beam collision conditions as well as the off-momentum electron background. Instantaneous and integrated luminosity values derived from this detector have become very useful for assuring the proper operation of the ALEPH detector. (orig.)

  9. Revisiting the luminosity function of single halo white dwarfs

    Science.gov (United States)

    Cojocaru, Ruxandra; Torres, Santiago; Althaus, Leandro G.; Isern, Jordi; García-Berro, Enrique

    2015-09-01

    Context. White dwarfs are the fossils left by the evolution of low- and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the Galactic halo. Aims: We present a population synthesis study of the luminosity function of halo white dwarfs, aimed at investigating which information can be derived from the currently available observed data. Methods: We employ an up-to-date population synthesis code based on Monte Carlo techniques, which incorporates the most recent and reliable cooling sequences for metal-poor progenitors as well as an accurate modeling of the observational biases. Results: We find that because the observed sample of halo white dwarfs is restricted to the brightest stars, only the hot branch of the white dwarf luminosity function can be used for these purposes, and that its shape function is almost insensitive to the most relevant inputs, such as the adopted cooling sequences, the initial mass function, the density profile of the stellar spheroid, or the adopted fraction of unresolved binaries. Moreover, since the cutoff of the observed luminosity has not yet been determined only the lower limits to the age of the halo population can be placed. Conclusions: We conclude that the current observed sample of the halo white dwarf population is still too small to obtain definite conclusions about the properties of the stellar halo, and the recently computed white dwarf cooling sequences, which incorporate residual hydrogen burning, should be assessed using metal-poor globular clusters.

  10. Very Low Luminosity Objects in Taurus Molecular Cloud

    Science.gov (United States)

    Sung, Ren-Shiang; Lai, Shih-Ping

    2015-08-01

    Very Low Luminosity Objects (VeLLOs) are the faintest protostars with intrinsic luminosity Lint ? 0.1 L?. Their low luminosities hints that they could be either very young, very low-mass, or even very young and low-mass protostars (i.e., proto brown dwarfs). Thus, identifying VeLLOs and investigating their properties are crucial for fully understanding of the earliest stage of star formation. The goal of this paper is to uncover VeLLOs in the Taurus molecular cloud and confirm that they are true Young Stellar Objects (YSOs). We use the catalogue from Taurus Spitzer Legacy Project and apply the selection criteria developed by Dunham et al. (2008) which are based on the Spectral Energy Distributions (SEDs) of typical Class 0 and early Class I protostars. New criteria for bolometric temperature and extinction are included to make up the lack of complete coverage of submm/mm maps in Taurus. As a result, we select 10 VeLLO candidates. In order to verify our VeLLO candidates are real YSOs, we observe 13CO (J=2-1), C18O (J=1-0), N2D+ (J=2-1), N2D+ (J=3-2), and N2H+ (J=1-0) with Arizona Radio Observatory (ARO). We detect N2H+ and N2D+ (J=2-1) in four VeLLO candidates and 13CO and C18O in all 10 VeLLO candidates (except SL05). We have also obtained SMA CO (J=2-1) maps toward the four VeLLOs with N2H+ and N2D+ detections to investigate their outflow properties. Based on the result of the N2D+/N2H+ column density ratio, two VeLLO candidates could be very young protostars and the other eight are more likely to be very low-mass protostars.

  11. Prospects for physics at high luminosity with CMS

    Directory of Open Access Journals (Sweden)

    Varela João

    2013-05-01

    Full Text Available The precision measurements of the properties of the recently discovered Higgs-like boson will be central to the future LHC physics program. In parallel the search for New Physics beyond the SM will continue. Higher luminosity will extend the mass reach and allow sensitive searches for possible subtle signatures for new physics. In this paper we review the potential sensitivity of CMS to a selection of relevant future physics scenarios accessible with the LHC upgrades and a correspondingly upgraded CMS detector.

  12. RESULTS FROM LUMINOSITY SCANS DURING THE RHIC 2000 RUN

    International Nuclear Information System (INIS)

    During the year 2000 run a total of eight beam scans (Vernier Scans) were performed at various interaction points (IF) at RHIC. During a Vernier Scan the experimental collision rates are recorded while the beams are stepwise scanned across each other. Vernier Scans yield transverse beam sizes as well as maximum luminosity and thus the absolute cross section, which with the limited data from the 2000 run we measured to be ? = 8.9 ± 0.3 barn at (?sNN) = 130 GeV. Also, Vernier Scans permit performance studies of the beam orbit control and local coupling

  13. APD performance in a luminosity monitor at LEP

    Science.gov (United States)

    Bartolomé, E.; Boix, G.; Casado, M. P.; Chmeissani, M.; Clemente, S.; Fernández, E.; Garrido, L.; Lorenz, E.; Martínez, M.; Merino, G.; Riu, I.; Sánchez, F.; Wright, A.

    2000-03-01

    Avalanche Photo-Diodes (APDs) are being used as optical readout elements in a sampling electromagnetic calorimeter made of alternate layers of tungsten and plastic scintillators. The calorimeter serves as a small-angle luminosity monitor in the stray magnetic field of the ALEPH detector at LEP (CERN). Its scintillators are coupled both to APDs and conventional PMTs simultaneously via wavelength shifter fibres. In this paper we present results on the overall performance of the APDs, including gain and stability versus time and energy, based on the direct comparison of the two photosensitive devices.

  14. The K Band Luminosity Function of High Redshift Clusters

    OpenAIRE

    Ellis, S. C .; Jones, L. R.

    2003-01-01

    K band observations of the galaxy populations of three high redshift (z=0.8-1.0), X-ray selected, massive clusters are presented. The observations reach a depth of K = 21.5, corresponding to K*+3.5 mag. The evolution of the galaxy properties are discussed in terms of their K band luminosity functions and the K band Hubble diagram of brightest cluster galaxies. The bulk of the galaxies, as characterised by the parameter K* from the Schechter (1976) function, are found to be...

  15. Optical and Near-IR Field Luminosity Functions

    OpenAIRE

    Loveday, Jon

    1998-01-01

    We present preliminary measurements of the b_J and K-band luminosity functions (LFs) of field galaxies obtained from optical and K-band imaging of a sample of galaxies selected from the Stromlo-APM Redshift Survey. The b_J LF is consistent with that previously published from photographic data. The K-band LF has been estimated over a range of 12 magnitudes and is reasonably well fit by a Schechter function with faint-end slope alpha = -1.2.

  16. ATLAS Higgs Physics Prospects at the High Luminosity LHC

    CERN Document Server

    Glaysher, Paul; The ATLAS collaboration

    2015-01-01

    A highly successful LHC Run 1 for ATLAS Higgs physics brought not only the discovery of a new particle but also provided initial measurements of its properties. To fully verify the Standard Model nature of the Higgs boson, or measure potential beyond the SM properties in the Higgs sector, will require a vastly larger dataset, delivered by the High Luminosity LHC. This document outlines studies on simulated data into the prospects of future measurements on Higgs couplings, Higgs self-couplings and constraints on discovering a high mass Higgs boson at the HL-LHC.

  17. AGB Variables and the Mira Period-Luminosity Relation

    OpenAIRE

    Whitelock, Patricia A; Feast, Michael W; van Leeuwen, Floor

    2008-01-01

    Published data for large amplitude asymptotic giant branch variables in the Large Magellanic Cloud are re-analysed to establish the constants for an infrared (K) period-luminosity relation of the form: Mk=rho[log P-2.38] + delta. A slope of rho=-3.51+/-0.20 and a zero point of delta=-7.15+/-0.06 are found for oxygen-rich Miras (if a distance modulus of 18.39+/-0.05 is used for the LMC). Assuming this slope is applicable to Galactic Miras we discuss the zero-point for these s...

  18. NGC4258 a jet-dominated low-luminosity AGN?

    CERN Document Server

    Yuan, F; Falcke, H; Biermann, P L; Yuan, Feng; Markoff, Sera; Falcke, Heino; Biermann, Peter L.

    2002-01-01

    Low-luminosity AGNs (LLAGNs) are a very important class of sources since they occupy a significant fraction of local galaxies. Their spectra differ significantly from the canonical luminous AGNs, most notably by the absence of the ``big blue bump''. In the present paper, taking a typical LLAGN--NGC4258--as an example, we investigate the origin of their spectral emission. The observational data of NGC4258 is extremely abundant, including water maser emission, putting very strict constraints to its theoretical models. The infrared (IR) spectrum is well described by a steep power-law form $f_{\

  19. Luminosity distance and redshift in the Szekeres inhomogeneous cosmological models

    CERN Document Server

    Nwankwo, Anthony; Ishak, Mustapha

    2010-01-01

    The Szekeres inhomogeneous models can be used to model the true lumpy universe that we observe. This family of exact solutions to Einstein's equations was originally derived with a general metric that has no symmetries. In this work, we perform analytical integrations of the non-radial null geodesics and derive new expressions for the affinely parameterized null tangent vector components, the area (and luminosity) distance and the redshift in these models. This work does not assume spherical or axial symmetry. The general results should be useful for comparisons of the general Szekeres inhomogeneous models to current and future cosmological data.

  20. Constraining the luminosity function parameters and population size of radio pulsars in globular clusters

    CERN Document Server

    Chennamangalam, Jayanth; Mandel, Ilya; Bagchi, Manjari

    2012-01-01

    The luminosity distribution of Galactic radio pulsars is believed to be log-normal in form. Applying this functional form to populations of pulsars in globular clusters, we employ Bayesian methods to explore constraints on the mean and standard deviation of the function, as well as the total number of pulsars in the cluster. Our analysis is based on an observed number of pulsars down to some limiting flux density, measurements of flux densities of individual pulsars, as well as diffuse emission from the direction of the cluster. We apply our analysis to Terzan 5 and demonstrate, under reasonable assumptions, that the number of potentially observable pulsars is in a 95.45% credible interval of 133$^{+101}_{-58}$. Beaming considerations would increase the true population size by approximately a factor of two.

  1. Constraining Neutrino Cooling using the Hot White Dwarf Luminosity Function in the Globular Cluster 47 Tucanae

    CERN Document Server

    Hansen, Bradley; Kalirai, Jason; Goldsbury, Ryan; Frewen, Shane; Heyl, Jeremy

    2015-01-01

    We present Hubble Space Telescope observations of the upper part (T_eff> 10 000 K) of the white dwarf cooling sequence in the globular cluster 47 Tucanae and measure a luminosity function of hot white dwarfs. Comparison with previous determinations from large scale field surveys indicates that the previously determined plateau at high effective temperatures is likely a selection effect, as no such feature is seen in this sample. Comparison with theoretical models suggests that the current estimates of white dwarf neutrino emission (primarily by the plasmon channel) are accurate, and variations are restricted to no more than a factor of two globally, at 95% confidence. We use these constraints to place limits on various proposed exotic emission mechanisms, including a non-zero neutrino magnetic moment, formation of axions, and emission of Kaluza-Klein modes into extra dimensions.

  2. Constraining Neutrino Cooling Using the Hot White Dwarf Luminosity Function in the Globular Cluster 47 Tucanae

    Science.gov (United States)

    Hansen, Brad M. S.; Richer, Harvey; Kalirai, Jason; Goldsbury, Ryan; Frewen, Shane; Heyl, Jeremy

    2015-08-01

    We present Hubble Space Telescope observations of the upper part ({T}{eff}\\gt {10}4 K) of the white dwarf cooling sequence in the globular cluster 47 Tucanae and measure a luminosity function of hot white dwarfs. Comparison with previous determinations from large-scale field surveys indicates that the previously determined plateau at high effective temperatures is likely a selection effect, as no such feature is seen in this sample. Comparison with theoretical models suggests that the current estimates of white dwarf neutrino emission (primarily by the plasmon channel) are accurate, and variations are restricted to no more than a factor of two globally, at 95% confidence. We use these constraints to place limits on various proposed exotic emission mechanisms, including a nonzero neutrino magnetic moment, formation of axions, and emission of Kaluza-Klein modes into extra dimensions.

  3. Luminosity limit due to the beam-beam interactions with or without crossing angle

    International Nuclear Information System (INIS)

    In recent high luminosity colliders, the finite crossing angle scheme becomes popular to gain the luminosity with multibunch or long bunch operation. Success of the KEKB factory showed that the finite crossing angle scheme has no problem achieving beam-beam parameters up to 0.05. We have studied the beam-beam interactions with and without crossing angle toward higher luminosity. We discuss how the crossing angle affects the beam-beam parameter and luminosity in the present KEKB using computer simulations. The simulations showed that crab cavities, which realize the head-on collision effectively, can be expected to double the luminosity

  4. Luminosity limit due to the beam-beam interactions with or without crossing angle

    Energy Technology Data Exchange (ETDEWEB)

    Ohmi, K.; Tawada, M.; Cai, Y.; Kamada, S.; Oide, K.; Qiang, J.

    2004-10-14

    In recent high luminosity colliders, the finite crossing angle scheme becomes popular to gain the luminosity with multibunch or long bunch operation. Success of the KEKB factory showed that the finite crossing angle scheme has no problem achieving beam-beam parameters up to 0.05. We have studied the beam-beam interactions with and without crossing angle toward higher luminosity. We discuss how the crossing angle affects the beam-beam parameter and luminosity in the present KEKB using computer simulations. The simulations showed that crab cavities, which realize the head-on collision effectively, can be expected to double the luminosity.

  5. The CLASS BL Lac sample: The Radio Luminosity Function

    CERN Document Server

    Marcha, M J M

    2013-01-01

    This paper presents a new sample of BL Lac objects selected from a deep (30 mJy) radio survey of flat spectrum radio sources (the CLASS blazar survey, henceforth CBS). The sample is one of the largest well defined samples in the low power regime with a total of 130 sources of which 55 satisfy the 'classical' optical BL Lac selection criteria, and the rest have indistinguishable radio properties. The primary goal of this study is to establish the Radio Luminosity Function (RLF) on firm statistical ground at low radio luminosities where previous samples have not been able to investigate. The gain of taking a peek at lower powers is the possibility to search for the flattening of the LF which is a feature predicted by the beaming model but which has remained elusive to observational confirmation. In this study we extend for the first time the BL Lac RLF down to very low radio powers ~10^22 W/Hz, ie, two orders of magnitude below the RLF currently available in the literature. In the process we confirm the importa...

  6. Revisiting the luminosity function of single halo white dwarfs

    CERN Document Server

    Cojocaru, R; Althaus, L G; Isern, J; García-Berro, E

    2015-01-01

    White dwarfs are the fossils left by the evolution of low-and intermediate-mass stars, and have very long evolutionary timescales. This allows us to use them to explore the properties of old populations, like the Galactic halo. We present a population synthesis study of the luminosity function of halo white dwarfs, aimed at investigating which information can be derived from the currently available observed data. We employ an up-to-date population synthesis code based on Monte Carlo techniques, that incorporates the most recent and reliable cooling sequences for metal poor progenitors as well as an accurate modeling of the observational biases. We find that because the observed sample of halo white dwarfs is restricted to the brightest stars only the hot branch of the white dwarf luminosity function can be used for such purposes, and that its shape function is almost insensitive to the most relevant inputs, like the adopted cooling sequences, the initial mass function, the density profile of the stellar spher...

  7. LHC Report: spring cleaning over, bunches of luminosity

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    Scrubbing was completed on Wednesday 13 April. The run had seen over 1000 bunches per beam successfully circulating at 450 GeV. Measurements showed that electron cloud activity in the cold regions had been suppressed. A decrease of vacuum activity in the warm regions demonstrated that the cleaning had also achieved the required results there. As discussed in the last Bulletin, the scrubbing was performed with high intensity bunches with 50 nanosecond spacing. Given the potential luminosity performance with this spacing (more bunches, higher bunch intensity from the injectors) and in the light of the results of the scrubbing run, the decision was taken to continue the 2011 physics run with this bunch spacing.   A few issues with 50 nanosecond spacing had to be resolved when standard operations for luminosity production resumed. Once things had been tidied up, stable beams were provided for the experiments, firstly with 228 bunches per beam and then with 336 bunches per beam. The 336 bunch fill that w...

  8. The Galaxy UV Luminosity Function Before the Epoch of Reionization

    CERN Document Server

    Mason, Charlotte; Treu, Tommaso

    2015-01-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a halo mass dependent, but redshift independent, star formation efficiency. This model improves on previous work by introducing a new self-consistent treatment of the halo star formation history, which allows us to make predictions at redshift $z>10$ (lookback time $\\lesssim500$ Myr), when growth is rapid. With a calibration at a single redshift to set the stellar to halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all the available observations ($0\\lesssim z\\lesssim10$). The significant drop in the luminosity density of currently detectable galaxies beyond $z\\sim8$ is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth $\\tau...

  9. Low extreme-ultraviolet luminosities impinging on protoplanetary disks

    Energy Technology Data Exchange (ETDEWEB)

    Pascucci, I.; Hendler, N. P. [Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Ricci, L. [Department of Astronomy, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Gorti, U.; Hollenbach, D. [SETI Institute, 189 Bernardo Ave., Mountain View, CA 94043 (United States); Brooks, K. J.; Contreras, Y., E-mail: pascucci@lpl.arizona.edu [Australia Telescope National Facility, P.O. Box 76, Epping, NSW 1710 (Australia)

    2014-11-01

    The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the extreme-ultraviolet (EUV) luminosity impinging on 14 disks around young (?2-10 Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10{sup 42} photons s{sup –1} for all sources without jets and lower than 5 × 10{sup 40} photons s{sup –1} for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [Ne II] 12.81 ?m luminosities from three disks with slow [Ne II]-detected winds. This indicates that the [Ne II] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars.

  10. Optical variability properties of high luminosity AGN classes

    CERN Document Server

    Stalin, C S; Wiita, P J; Sagar, Ram; Wiita, Paul J.

    2003-01-01

    We present the results of a comparative study of the intra-night optical variability (INOV) characteristics of radio-loud and radio-quiet quasars, which involves a systematic intra-night optical monitoring of seven sets of high luminosity AGNs covering the redshift range {it z} $simeq 0.2$ to {it z} $simeq 2.2$. The sample, matched in the optical luminosity -- redshift (M$_B$ -- z) plane, consists of seven radio-quiet quasars (RQQs), eight radio lobe-dominated quasars (LDQs), six radio core-dominated quasars (CDQs) and five BL Lac objects (BLs). Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to detect INOV with amplitudes as low as 1%. Present observations cover a total of 113 nights (720 hours) with only a single quasar monitored as continuously as possible on a night. Considering cases of only unambiguous detections of INOV we have estimated duty cycles (DCs) of 17%, 12%, 20% and 72% respectively for RQQs, LDQs, CDQs, and BLs. The low amplitude and low DC of INOV sh...

  11. The Luminosities and Diameters of Mira Variables from Hipparcos Parallaxes

    CERN Document Server

    Whitelock, P A; Feast, M W

    1997-01-01

    Hipparcos trigonometrical parallaxes of Mira-type variables have been combined with ground-based angular diameter measurements to derive linear diameters. Of eight stars with ground-based data, six have diameters indicating overtone pulsation whilst two, both with periods over 400 day, are pulsating in the fundamental. Hipparcos parallaxes of 11 Miras have been combined with extensive infrared photometry to determine the zero-point of the Mira period-luminosity relation. Adopting the relation at K (2.2 micron), since this is less likely to be subject to abundance effects than that at Mbol, leads to a distance modulus for the LMC of 18.6 mag with a uncertainty of slightly less than 0.2 mag. A brief discussion is given of the preliminary analysis of the parallaxes of a much larger sample of Miras. Some consideration is given to possible problems in interpreting the Hipparcos data which arise because of the physical characteristics of the Mira variables. Finally the apparent low-luminosity of the carbon Mira, R ...

  12. On the Form of the HII Region Luminosity Function

    CERN Document Server

    Oey, M S

    1997-01-01

    Observed variations in the HII region luminosity function (HII LF) seen in spiral arm vs. interarm regions, and different galactic Hubble type, can be explained simply by evolutionary effects and maximum number of ionizing stars per cluster. We present Monte Carlo simulations of the HII LF, drawing the number of ionizing stars N_* from a power-law distribution of constant slope, and the stellar masses from a Salpeter IMF with an upper-mass limit of 100 M_sol. We investigate the evolution of the HII LF, as determined by stellar main-sequence lifetimes and ionizing luminosities, for a single burst case and continuous creation of the nebular population. Shallower HII LF slopes measured for the arms of spiral galaxies can be explained as a composite slope, expected for a zero-age burst population, whereas the interarm regions tend to be dominated by evolved rich clusters described by a single, steeper slope. Steeper slopes in earlier-type galaxies can be explained simply by a lower maximum N_* cutoff found for th...

  13. ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC

    CERN Document Server

    Valderanis, Chrysostomos; The ATLAS collaboration

    2015-01-01

    ATLAS Muon Spectrometer Upgrades for the High Luminosity LHC The luminosity of the LHC will increase up to 2x10^34 cm-2s-1 after the long shutdown in 2019 (phase-1 upgrade) and up to 7x10^34 cm-2s-1 after the long shutdown in 2025 (phase-2 upgrade). In order to cope with the increased particle fluxes, upgrades are envisioned for the ATLAS muon spectrometer. At phase-1, the current innermost stations of the ATLAS muon endcap tracking system (the Small Wheels) will be upgraded with 2x4-layer modules of Micromega detectors, sandwiched by two 4 layer modules of small strip Thin Gap Chambers on either side. Each 4-layer module of the so-called New Small Wheels covers a surface area of approximately 2 to 3 m2 for a total active area of 1200 m2 each for the two technologies. On such large area detectors, the mechanical precision (30 \\mu m along the precision coordinate and 80 \\mu m along the beam) is a key point and must be controlled and monitored along the process of construction and integration. The design and re...

  14. Radio variability survey of very low luminosity protostars

    International Nuclear Information System (INIS)

    Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

  15. Absolute luminosity measurements with the LHCb detector at the LHC

    CERN Document Server

    Aaij, R; Adinolfi, M; Adrover, C; Affolder, A; Ajaltouni, Z; Albrecht, J; Alessio, F; Alexander, M; Alkhazov, G; Alvarez Cartelle, P; Alves, A A; Amato, S; Amhis, Y; Anderson, J; Appleby, R B; Aquines Gutierrez, O; Archilli, F; Arrabito, L; Artamonov, A; Artuso, M; Aslanides, E; Auriemma, G; Bachmann, S; Back, J J; Bailey, D S; Balagura, V; Baldini, W; Barlow, R J; Barschel, C; Barsuk, S; Barter, W; Bates, A; Bauer, C; Bauer, Th; Bay, A; Bediaga, I; Belous, K; Belyaev, I; Ben-Haim, E; Benayoun, M; Bencivenni, G; Benson, S; Benton, J; Bernet, R; Bettler, M-O; van Beuzekom, M; Bien, A; Bifani, S; Bizzeti, A; Bjørnstad, P M; Blake, T; Blanc, F; Blanks, C; Blouw, J; Blusk, S; Bobrov, A; Bocci, V; Bondar, A; Bondar, N; Bonivento, W; Borghi, S; Borgia, A; Bowcock, T J V; Bozzi, C; Brambach, T; van den Brand, J; Bressieux, J; Brett, D; Brisbane, S; Britsch, M; Britton, T; Brook, N H; Brown, H; Büchler-Germann, A; Burducea, I; Bursche, A; Buytaert, J; Cadeddu, S; Caicedo Carvajal, J M; Callot, O; Calvi, M; Calvo Gomez, M; Camboni, A; Campana, P; Carbone, A; Carboni, G; Cardinale, R; Cardini, A; Carson, L; Carvalho Akiba, K; Casse, G; Cattaneo, M; Charles, M; Charpentier, Ph; Chiapolini, N; Ciba, K; Cid Vidal, X; Ciezarek, G; Clarke, P E L; Clemencic, M; Cliff, H V; Closier, J; Coca, C; Coco, V; Cogan, J; Collins, P; Constantin, F; Conti, G; Contu, A; Cook, A; Coombes, M; Corti, G; Cowan, G A; Currie, R; D'Almagne, B; D'Ambrosio, C; David, P; De Bonis, I; De Capua, S; De Cian, M; De Lorenzi, F; De Miranda, J M; De Paula, L; De Simone, P; Decamp, D; Deckenhoff, M; Degaudenzi, H; Deissenroth, M; Del Buono, L; Deplano, C; Deschamps, O; Dettori, F; Dickens, J; Dijkstra, H; Diniz Batista, P; Donleavy, S; Dordei, F; Dosil Suárez, A; Dossett, D; Dovbnya, A; Dupertuis, F; Dzhelyadin, R; Eames, C; Easo, S; Egede, U; Egorychev, V; Eidelman, S; van Eijk, D; Eisele, F; Eisenhardt, S; Ekelhof, R; Eklund, L; Elsasser, Ch; d'Enterria, D G; Esperante Pereira, D; Estève, L; Falabella, A; Fanchini, E; Färber, C; Fardell, G; Farinelli, C; Farry, S; Fave, V; Fernandez Albor, V; Ferro-Luzzi, M; Filippov, S; Fitzpatrick, C; Fontana, M; Fontanelli, F; Forty, R; Frank, M; Frei, C; Frosini, M; Furcas, S; Gallas Torreira, A; Galli, D; Gandelman, M; Gandini, P; Gao, Y; Garnier, J-C; Garofoli, J; Garra Tico, J; Garrido, L; Gaspar, C; Gauvin, N; Gersabeck, M; Gershon, T; Ghez, Ph; Gibson, V; Gligorov, V V; Göbel, C; Golubkov, D; Golutvin, A; Gomes, A; Gordon, H; Grabalosa Gándara, M; Graciani Diaz, R; Granado Cardoso, L A; Graugés, E; Graziani, G; Grecu, A; Gregson, S; Gui, B; Gushchin, E; Guz, Yu; Gys, T; Haefeli, G; Haen, C; Haines, S C; Hampson, T; Hansmann-Menzemer, S; Harji, R; Harnew, N; Harrison, J; Harrison, P F; He, J; Heijne, V; Hennessy, K; Henrard, P; Hernando Morata, J A; van Herwijnen, E; Hicks, E; Hofmann, W; Holubyev, K; Hopchev, P; Hulsbergen, W; Hunt, P; Huse, T; Huston, R S; Hutchcroft, D; Hynds, D; Iakovenko, V; Ilten, P; Imong, J; Jacobsson, R; Jaeger, A; Jahjah Hussein, M; Jans, E; Jansen, F; Jaton, P; Jean-Marie, B; Jing, F; John, M; Johnson, D; Jones, C R; Jost, B; Kandybei, S; Karacson, M; Karbach, T M; Keaveney, J; Kerzel, U; Ketel, T; Keune, A; Khanji, B; Kim, Y M; Knecht, M; Koblitz, S; Koppenburg, P; Kozlinskiy, A; Kravchuk, L; Kreplin, K; Kreps, M; Krocker, G; Krokovny, P; Kruse, F; Kruzelecki, K; Kucharczyk, M; Kukulak, S; Kumar, R; Kvaratskheliya, T; La Thi, V N; Lacarrere, D; Lafferty, G; Lai, A; Lambert, D; Lambert, R W; Lanciotti, E; Lanfranchi, G; Langenbruch, C; Latham, T; Le Gac, R; van Leerdam, J; Lees, J-P; Lefèvre, R; Leflat, A; Lefrançois, J; Leroy, O; Lesiak, T; Li, L; Li Gioi, L; Lieng, M; Liles, M; Lindner, R; Linn, C; Liu, B; Liu, G; Lopes, J H; Lopez Asamar, E; Lopez-March, N; Luisier, J; Machefert, F; Machikhiliyan, I V; Maciuc, F; Maev, O; Magnin, J; Malde, S; Mamunur, R M D; Manca, G; Mancinelli, G; Mangiafave, N; Marconi, U; Märki, R; Marks, J; Martellotti, G; Martens, A; Martin, L; Martín Sánchez, A; Martinez Santos, D; Massafferri, A; Matev, R; Mathe, Z; Matteuzzi, C; Matveev, M; Maurice, E; Maynard, B; Mazurov, A; McGregor, G; McNulty, R; Mclean, C; Meissner, M; Merk, M; Merkel, J; Messi, R; Miglioranzi, S; Milanes, D A; Minard, M-N; Monteil, S; Moran, D; Morawski, P; Mountain, R; Mous, I; Muheim, F; Müller, K; Muresan, R; Muryn, B; Musy, M; Mylroie-Smith, J; Naik, P; Nakada, T; Nandakumar, R; Nardulli, J; Nasteva, I; Nedos, M; Needham, M; Neufeld, N; Nguyen-Mau, C; Nicol, M; Nies, S; Niess, V; Nikitin, N; Oblakowska-Mucha, A; Obraztsov, V; Oggero, S; Ogilvy, S; Okhrimenko, O; Oldeman, R; Orlandea, M; Otalora Goicochea, J M; Owen, P; Pal, B; Palacios, J; Palutan, M; Panman, J; Papanestis, A; Pappagallo, M; Parkes, C; Parkinson, C J; Passaleva, G; Patel, G D; Patel, M; Paterson, S K; Patrick, G N; Patrignani, C; Pavel-Nicorescu, C

    2012-01-01

    Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic ``van der Meer scan'' method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overall precision of 3.5\\% in the absolute lumi...

  16. The metric of the cosmos from luminosity and age data

    International Nuclear Information System (INIS)

    This paper presents the algorithm for determining the Lemaître-Tolman model that best fits given datasets for maximum stellar ages, and SNIa luminosities, both as functions of redshift. It then applies it to current cosmological data. Special attention must be given to the handling of the origin, and the region of the maximum diameter distances. As with a previous combination of datasets (galaxy number counts and luminosity distances versus redshift), there are relationships that must hold at the region of the maximum diameter distance, which are unlikely to be obeyed exactly by real data. We show how to make corrections that enable a self-consistent solution to be found. We address the questions of the best way to approximate discrete data with smooth functions, and how to estimate the uncertainties of the output — the 3 free functions that determine a specific Lemaître-Tolman metric. While current data does not permit any confidence in our results, we show that the method works well, and reasonable Lemaître-Tolman models do fit with or without a cosmological constant

  17. Radiation hydrodynamics of high-luminosity accretion into black holes

    International Nuclear Information System (INIS)

    To extend Shapiro's calculations of black hole accretion to the regimes of interstellar gas densities and of black hole masses for which emergent luminosities are expected to be high, the radiation hydrodynamics of spherically symmetric gas flows in static isotropic metrics is discussed. Since for the more luminous objects the optical depth of the accretion volume becomes large, particular attention has to be paid to radiative transfer through non-Euclidean spaces, and a method for solving the full transfer problem is presented. The method is applied to accretion into black holes of mass between 10 solar masses and 105 solar masses, under the conservative assumption that all other heat sources, like dissipation of magnetic or turbulent energy, can be neglected in comparison to the compressional work term, pdV. In the interstellar gas parameter range of interest, the radiation field is then dominated by emission and absorption of synchrotron radiation from inner zones of the flow. Temperature stratifications, luminosities and emergent spectra resulting from these processes are calculated. (Auth.)

  18. High luminosity electron-hadron collider eRHIC

    Energy Technology Data Exchange (ETDEWEB)

    Ptitsyn, V.; Aschenauer, E.; Bai, M.; Beebe-Wang, J.; Belomestnykh, S.; Ben-Zvi, I.; Blaskiewicz, M..; Calaga, R.; Chang, X.; Fedotov, A.; Gassner, D.; Hammons, L.; Hahn, H.; Hammons, L.; He, P.; Hao, Y.; Jackson, W.; Jain, A.; Johnson, E.C.; Kayran, D.; Kewisch, J.; Litvinenko, V.N.; Luo, Y.; Mahler, G.; McIntyre, G.; Meng, W.; Minty, M.; Parker, B.; Pikin, A.; Rao, T.; Roser, T.; Skaritka, J.; Sheehy, B.; Skaritka, J.; Tepikian, S.; Than, Y.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Webb, S.; Wu, Q.; Xu, W.; Pozdeyev, E.; Tsentalovich, E.

    2011-03-28

    We present the design of a future high-energy high-luminosity electron-hadron collider at RHIC called eRHIC. We plan on adding 20 (potentially 30) GeV energy recovery linacs to accelerate and to collide polarized and unpolarized electrons with hadrons in RHIC. The center-of-mass energy of eRHIC will range from 30 to 200 GeV. The luminosity exceeding 10{sup 34} cm{sup -2} s{sup -1} can be achieved in eRHIC using the low-beta interaction region with a 10 mrad crab crossing. We report on the progress of important eRHIC R&D such as the high-current polarized electron source, the coherent electron cooling, ERL test facility and the compact magnets for recirculation passes. A natural staging scenario of step-by-step increases of the electron beam energy by building-up of eRHIC's SRF linacs is presented.

  19. The z=5 Quasar Luminosity Function from SDSS Stripe 82

    CERN Document Server

    McGreer, Ian D; Fan, Xiaohui; Richards, Gordon T; Strauss, Michael A; Ross, Nicholas P; White, Martin; Shen, Yue; Schneider, Donald P; Myers, Adam D; Brandt, W Niel; DeGraf, Colin; Glikman, Eilat; Ge, Jian; Streblyanska, Alina

    2012-01-01

    We present a measurement of the Type I quasar luminosity function at z=5 using a large sample of spectroscopically confirmed quasars selected from optical imaging data. We measure the bright end (M_1450<-26) with Sloan Digital Sky Survey (SDSS) data covering ~6000 deg^2, then extend to lower luminosities (M_1450<-24) with newly discovered, faint z~5 quasars selected from 235 deg^2 of deep, coadded imaging in the SDSS Stripe 82 region (the celestial equator in the Southern Galactic Cap). The faint sample includes 14 quasars with spectra obtained as ancillary science targets in the SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), and 59 quasars observed at the MMT and Magellan telescopes. We construct a well-defined sample of 4.7

  20. Radio variability survey of very low luminosity protostars

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Minho; Kang, Miju [Korea Astronomy and Space Science Institute, 776 Daedeokdaero, Daejeon 305-348 (Korea, Republic of); Lee, Jeong-Eun, E-mail: minho@kasi.re.kr [Department of Astronomy and Space Science, Kyung Hee University, Yongin, Gyeonggi 446-701 (Korea, Republic of)

    2014-07-01

    Ten very low luminosity objects were observed multiple times in the 8.5 GHz continuum in search of protostellar magnetic activities. A radio outburst of IRAM 04191+1522 IRS was detected, and the variability timescale was about 20 days or shorter. The results of this survey and archival observations suggest that IRAM 04191+1522 IRS is in active states about half the time. Archival data show that L1014 IRS and L1148 IRS were detectable previously and suggest that at least 20%-30% of very low luminosity protostars are radio variables. Considering the variability timescale and flux level of IRAM 04191+1522 IRS and the previous detection of the circular polarization of L1014 IRS, the radio outbursts of these protostars are probably caused by magnetic flares. However, IRAM 04191+1522 IRS is too young and small to develop an internal convective dynamo. If the detected radio emission is indeed coming from magnetic flares, the discovery implies that the flares may be caused by the fossil magnetic fields of interstellar origin.

  1. A primer on detectors in high luminosity environment

    International Nuclear Information System (INIS)

    The following remarks are relevant to the problem of balancing luminosity versus energy in new HEP construction. In a previous study, it was stated that the only experiment that would succeed at a luminosity of 10/sup 33/cm/sup -2/sec/sup -1/ was one in which the apparatus was shielded from the collision region by massive quantity of steel. In 1981, this opinion was confirmed by an authority in the field. It may be instructive to review the progress of collider detectors over the past decade. In 1973, the time resolution or, better, the integrating time of tracking detectors was --100 ns. In 1982, this time has remained the same since PWC's are still the fastest tracking devices available. The fundamental limit is the saturated drift velocity of electrons in gases. Better resolution and three dimensional properties have led to the choice of drift chambers and TPC's which have considerably longer integration times. A new characteristic of 1982 detectors is the increasing pervasiveness of calorimeters which have become indispensable devices for measurement of electromagnetic and hadronic energy, especially at momenta where magnetic measurements become imprecise. Calorimeters, because of their innate geometric dimensions set by the nuclear mean free path and their distance from the interaction point have integration times of --200-1000 ns. Of course this is the present state of the art which depends on the properties of BBQ, gas chambers, liquid argon, lead glass, etc

  2. Jet or Shock Breakout? The Low-Luminosity GRB 060218

    CERN Document Server

    Irwin, C M

    2015-01-01

    We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived ($t_j \\sim 3000$ s) central engine and accompanying low-luminosity ($L_j \\sim 10^{47}$ erg s$^{-1}$), semirelativistic ($\\gamma \\sim 10$) jet; (2) a low-mass ($ \\sim 10^{-2} M_\\odot$) envelope surrounding the progenitor star; and (3) a modest amount of dust ($A_V \\sim 0.1$ mag) in the interstellar environment. Blackbody emission from the transparency radius in a low-power jet outflow can fit the prompt thermal X-ray emission, and the nonthermal X-rays and gamma-rays may be produced via Compton scattering of thermal photons from hot leptons in the jet interior or the external shocks. The later mildly relativistic phase of this outflow can produce the radio emission via synchrotron radiation from the forward shock. Meanwhile, interaction of the associated SN 2006aj with a circumstellar envelope extending to $\\sim10^{13}$ cm can expla...

  3. A reanalysis of the luminosities of clusters of galaxies in the EMSS sample with 0.3 < z < 0.6

    CERN Document Server

    Ellis, S C

    2002-01-01

    The X-ray luminosities of the Einstein Extended Medium Sensitivity Survey (EMSS) clusters of galaxies with redshifts 0.3250 kpc (the constant value assumed in the EMSS), the new luminosities are 2.2 +/- 0.15 times the previous measurements. The X-ray luminosity function (XLF) at 0.3factor ~2 since z=0.4. The implications of this result are discussed in terms of constraints on the cosmological parameter Omega_0.

  4. The Luminosity Function of Galaxies as modeled by a left truncated beta distribution

    CERN Document Server

    Zaninetti, L

    2014-01-01

    A first new luminosity functions of galaxies can be built starting from a left truncated beta probability density function, which is characterized by four parameters. In the astrophysical conversion, the number of parameters increases by one, due to the addition of the overall density of galaxies. A second new galaxy luminosity function is built starting from a left truncated beta probability for the mass of galaxies once a simple nonlinear relationship between mass and luminosity is assumed; in this case the number of parameters is six because the overall density of galaxies and a parameter that regulates mass and luminosity are added. The two new galaxy luminosity functions with finite boundaries were tested on the Sloan Digital Sky Survey (SDSS) in five different bands; the results produce a "better fit" than the Schechter luminosity function in two of the five bands considered. A modified Schechter luminosity function with four parameters has been also analyzed.

  5. Extra-galactic high-energy transients: event rate densities and luminosity functions

    CERN Document Server

    Sun, Hui; Li, Zhuo

    2015-01-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with an associated relativistic jet. In this paper, we apply a unified method to systematically study the redshift-dependent event rate densities and the global luminosity functions (ignoring redshift evolution) of these transients. We introduce some empirical formulae for the redshift-dependent event rate densities for different types of transients, and derive the local specific event rate density, which also represents its global luminosity function. Long GRBs have a large enough sample to reveal features in the global luminosity function, which is best characterized as a triple power law. All the other transients are consistent with having a single power law luminosity function. The total event rate density depends on the minimum luminosity, and...

  6. L1Track: a Fast Level 1 Track Trigger for the ATLAS High Luminosity Upgrade

    CERN Document Server

    Cerri, Alessandro; The ATLAS collaboration

    2015-01-01

    With the planned high-luminosity upgrade of the LHC, the ATLAS detector will see its collision rate increased by approximately a factor of 5 with respect to the current LHC design. Due to this the pile-up collisions will increase by a similar factor. The earliest, hardware based, ATLAS trigger stage ("Level 1") will have to provide an higher rejection factor in a more difficult environment. The Level 1 trigger architecture needs therefore to be improved. A new Level 1 trigger architecture is under study, which, in addition of the “regions of interest” identified by the calorimetry and the muon chambers, also includes the possibility of extracting tracking information and use it for the decision taking process. The expected trigger rates at HL-LHC and the available latency are the key ingredients that will drive the new design. A low-latency and accurate tracking trigger system is being developed in the context of this additional trigger refinement. The design results in a substantial modification of the A...

  7. Type Ia Supernova Spectral Line Ratios as LuminosityIndicators

    Energy Technology Data Exchange (ETDEWEB)

    Bongard, Sebastien; Baron, E.; Smadja, G.; Branch, David; Hauschildt, Peter H.

    2005-12-07

    Type Ia supernovae have played a crucial role in thediscovery of the dark energy, via the measurement of their light curvesand the determination of the peak brightness via fitting templates to theobserved lightcurve shape. Two spectroscopic indicators are also known tobe well correlated with peak luminosity. Since the spectroscopicluminosity indicators are obtained directly from observed spectra, theywill have different systematic errors than do measurements usingphotometry. Additionally, these spectroscopic indicators may be usefulfor studies of effects of evolution or age of the SNe~;Ia progenitorpopulation. We present several new variants of such spectroscopicindicators which are easy to automate and which minimize the effects ofnoise. We show that these spectroscopic indicators can be measured byproposed JDEM missions such as snap and JEDI.

  8. 130 mm Aperture Quadrupoles for the LHC Luminosity Upgrade

    CERN Document Server

    Todesco, E; Mailfert, A

    2007-01-01

    Several studies for the LHC luminosity upgrade pointed out the need for low-beta quadrupoles with apertures larger than the present baseline (70 mm). In this paper we focus on the design issues of a 130 mm aperture quadrupole. We first consider the Nb-Ti option, presenting a magnetic design with the LHC dipole and quadrupole cables. We study the electromagnetic forces and we discuss the field quality constraints. For the Nb3Sn option, we sketch three designs, two based on the LARP 10 mm width cable, and one on a larger cable with the same strand. The issue of the stress induced by the e.m. forces, which is critical for the Nb3Sn, is discussed using both scaling laws and finite element models.

  9. New Results on the Precision of the LEP Luminosity

    Energy Technology Data Exchange (ETDEWEB)

    Jadach, S. [Theory Division, CERN, Geneva (European Organization for Nuclear Research (CERN)); Melles, M. [Department of Theoretical Physics, University of Durham, Durham (United Kingdom); Ward, B.F.L.; Yost, S.A. [Department of Physics and Astronomy, University of Tennessee, Knoxville (United States)

    1999-06-01

    We present recent progress on the theoretical precision limits of the LEP luminosity process, as calculated by the Monte Carlo event generator BHLUMI4.O4. We include exact results for all two-photon radiative corrections to the process e{sup +}e{sup -} {yields} e{sup +}e{sup -} at small angles and LEP energies. These results reduce the precision estimate for the O({alpha}{sup 2}) photonic radiative correction from 0.1% to 0.027%, leading to an overall precision of 0.061% for the currently published version of BHLUMI4.O4. This precision level is important for the final precision Z physics measurements at LEP1. We also present precision estimates for LEP2. (author) 18 refs, 2 figs, 1 tab

  10. Levitating atmospheres of Eddington-luminosity neutron stars

    CERN Document Server

    Wielgus, Maciek; Kluzniak, Wlodek; Abramowicz, Marek; Narayan, Ramesh

    2015-01-01

    We construct models of static, spherically symmetric shells supported by the radiation flux of a luminous neutron star in the Schwarzschild metric. The atmospheres are disconnected from the star and levitate above its surface. Gas pressure and density inversion appear in the inner region of these atmospheres, which is a purely relativistic phenomenon. We account for the scattering opacity dependence on temperature and utilize the relativistic M1 closure scheme for the radiation tensor, hence allowing for a fully GR-consistent treatment of the photon flux and radiation tensor anisotropy. In this way we are able to address atmospheres of both large and moderate/low optical depths with the same set of equations. We discuss properties of the levitating atmospheres and find that they may indeed be optically thick, with the distance between star surface and the photosphere expanding as luminosity increases. These results may be relevant for the photosphereric radius expansion X-ray bursts.

  11. Optical spectroscopy of liners and low-luminosity Seyfert nuclei

    CERN Document Server

    Ho, L C

    1996-01-01

    An unprecedentedly large number of LINERs has been discovered in a recently completed optical spectroscopic survey of nearby galaxies, allowing several statistical properties of the host galaxies and of the line-emitting regions to be examined reliably for the first time. As a consequence of the many detections and some revised classifications, the detailed demographics of emission-line nuclei have been updated from those given in older surveys. Consistent with previous studies, it is found that LINERs are extremely common in the present epoch, comprising approximately 1/3 of all galaxies with B <= 12.5 mag. If all LINERs are nonstellar in origin, then they are the dominant constituents of the active galactic nucleus population. Many fundamental characteristics of LINERs closely resemble those of low-luminosity Seyfert nuclei, although several aspects of their narrow-line regions appear to differ in a systematic manner. These differences could hold important clues to the key parameters controlling the ioni...

  12. Robust Constraint of Luminosity Function Evolution through MCMC Sampling

    Science.gov (United States)

    Kurinsky, Noah; Sajina, Anna

    2014-05-01

    We present a new galaxy survey simulation package, which combines the power of Markov Chain Monte Carlo (MCMC) sampling with a robust and adaptable model of galaxy evolution. The aim of this code is to aid in the characterization and study of new and existing galaxy surveys. In this paper we briefly describe the MCMC implementation and the survey simulation methodology and associated tools. A test case of this full suite was to constrain the evolution of the IR Luminosity Function (LF) based on the HerMES (Herschel SPIRE) survey of the Spitzer First Look Survey field. The initial results are consistent with previous studies, but our more general approach should be of wider benefit to the community.

  13. Robust Constraint of Luminosity Function Evolution Through MCMC Sampling

    CERN Document Server

    Kurinsky, Noah

    2014-01-01

    We present a new galaxy survey simulation package, which combines the power of Markov Chain Monte Carlo (MCMC) sampling with a robust and adaptable model of galaxy evolution. The aim of this code is to aid in the characterization and study of new and existing galaxy surveys. In this paper we briefly describe the MCMC implementation and the survey simulation methodology and associated tools. A test case of this full suite was to constrain the evolution of the IR Luminosity Function (LF) based on the HerMES (Herschel SPIRE) survey of the Spitzer First Look Survey field. The initial results are consistent with previous studies, but our more general approach should be of wider benefi?t to the community.

  14. Fast Frontend Electronics for high luminosity particle detectors

    CERN Document Server

    Cardinali, M; Bondy, M I Ferretti; Hoek, M; Lauth, W; Rosner, C; Sfienti, C; Thiel, M

    2015-01-01

    Future experiments of nuclear and particle physics are moving towards the high luminosity regime, in order to access suppressed processes like rare B decays or exotic charmonium resonances. In this scenario, high rate capability is a key requirement for electronics instrumentation, together with excellent timing resolution for precise event reconstruction. The development of dedicated FrontEnd Electronics (FEE) for detectors has become increasingly challenging. A current trend in R&D is towards multipurpose FEE which can be easily adapted to a great variety of detectors, without impairing the required high performance. We report on high-precision timing solutions which utilise high-bandwidth preamplifiers and fast discriminators providing Time-over-Threshold information, which can be used for charge measurements or walk corrections thus improving the obtainable timing resolution. The output signal are LVDS and can be directly fed into a multi-hit TDC readout. The performance of the electronics was investi...

  15. A High Resolution Luminosity Monitor for SLAC Experiment E158

    International Nuclear Information System (INIS)

    A calorimetric detector based on ionization has been employed as a low-angle luminosity monitor for the parity violation experiment E158 at SLAC. The experiment utilizes a 50 GeV polarized electron beam on a liquid hydrogen target. The detector looks at high energy Mott and Moller scattered electrons, with a per pulse flux of 4 x 108 particles. This large signal allows the device to serve the dual role of monitoring target density fluctuations, as well as detecting false asymmetries. In the first physics run of the experiment, the detector has achieved a per-pulse intensity asymmetry resolution of 170 parts per million. The linearity of the device also has been verified to ? 1%

  16. Weighing neutrinos using high redshift galaxy luminosity functions

    CERN Document Server

    Jose, Charles; Subramanian, Kandaswamy; Srianand, Raghunathan

    2011-01-01

    Laboratory experiments measuring neutrino oscillations, indicate small mass differences between different mass eigenstates of neutrinos. The absolute mass scale is however not determined, with at present the strongest upper limits coming from astronomical observations rather than terrestrial experiments. The presence of massive neutrinos suppresses the growth of perturbations below a characteristic mass scale, thereby leading to a decreased abundance of collapsed dark matter halos. Here we show that this effect can significantly alter the predicted luminosity function (LF) of high redshift galaxies. In particular we demonstrate that a stringent constraint on the neutrino mass can be obtained using the well measured galaxy LF and our semi-analytic structure formation models. Combining the constraints from the Wilkinson Microwave Anisotropy Probe 7 year (WMAP7) data with the LF data at z = 4, we get a limit on the sum of the masses of 3 degenerate neutrinos \\Sigma m_\

  17. CKM fits as a function of luminosity (Time)

    International Nuclear Information System (INIS)

    Possible scenarios for CKM fits in the years 2005 and 2010 are presented using B- and K - physics results from extrapolated luminosities for B-factories at the ?(4S), for the hadron machines at Tevatron and LHC and experiments for rare kaon decays. The study provides an estimate of what precision for the CKM matrix elements can be achieved if all relevant experiments and accelerators, including upgrades for the existing e+e- machines, reach their design goals. It is intended to give information used to explore which type of future experiments are needed to cover all relevant physics topics related to the CKM matrix and the search of physics beyond the Standard Model. (authors)

  18. EGS4 calculations for a PEP-II luminosity monitor

    International Nuclear Information System (INIS)

    The Asymmetric B-Factory currently being built at SLAC consists of a 9 GeV electron storage ring and a 3 GeV positron storage ring, known as PEP-II, and a large detector called BABAR. Because the commissioning of PEP-II starts approximately one year ahead of the installation of BABAR, it is desirable to have a dedicated system in place beforehand for measuring and optimizing the luminosity of the colliding beams. Accordingly, the EGS4 Code System has been used in the design of a quartz-glass Cherenkov hodoscope that monitors high-energy showers, initiated by photons emanating from radiative-Bhabba interactions at the Interaction Point located 8.5 meters upbeam. In this paper the authors present the results of a series of EGS4 calculations to determine the spatial resolution of such a detector, as well as to determine if there will be any serious limitations caused by radiation damage

  19. Luminosity distance and redshift in the Szekeres inhomogeneous cosmological models

    Energy Technology Data Exchange (ETDEWEB)

    Nwankwo, Anthony; Ishak, Mustapha; Thompson, John, E-mail: Anthony@utdallas.edu, E-mail: mishak@utdallas.edu, E-mail: jpt043000@utdallas.edu [Department of Physics, The University of Texas at Dallas, Richardson, TX 75083 (United States)

    2011-05-01

    The Szekeres inhomogeneous models can be used to model the true lumpy universe that we observe. This family of exact solutions to Einstein's equations was originally derived with a general metric that has no symmetries. In this work, we develop and use a framework to integrate the angular diameter and luminosity distances in the general Szekeres models. We use the affine null geodesic equations in order to derive a set of first-order ordinary differential equations that can be integrated numerically to calculate the partial derivatives of the null vector components. These equations allow the integration in all generality of the distances in the Szekeres models and some examples are given. The redshift is determined from simultaneous integration of the null geodesic equations. This work does not assume spherical or axial symmetry, and the results will be useful for comparisons of the general Szekeres inhomogeneous models to current and future cosmological data.

  20. Luminosity Bias (II): The Cosmic Web of the First Stars

    CERN Document Server

    Barkana, Rennan

    2013-01-01

    Understanding the formation and evolution of the first stars and galaxies represents one of the most exciting frontiers in astronomy. Since the universe was filled with neutral hydrogen at early times, the most promising method for observing the epoch of the first stars is using the prominent 21-cm spectral line of the hydrogen atom. Current observational efforts are focused on the reionization era (cosmic age t ~ 500 Myr), with earlier times considered much more challenging. However, the next frontier of even earlier galaxy formation (t ~ 200 Myr) is emerging as a promising observational target. This is made possible by a recently noticed effect of a significant relative velocity between the baryons and dark matter at early times. The velocity difference suppresses star formation, causing a unique form of early luminosity bias. The spatial variation of this suppression enhances large-scale clustering and produces a prominent cosmic web on 100 comoving Mpc scales in the 21-cm intensity distribution. This stru...

  1. The Galaxy UV Luminosity Function before the Epoch of Reionization

    Science.gov (United States)

    Mason, Charlotte A.; Trenti, Michele; Treu, Tommaso

    2015-11-01

    We present a model for the evolution of the galaxy ultraviolet (UV) luminosity function (LF) across cosmic time where star formation is linked to the assembly of dark matter halos under the assumption of a mass-dependent, but redshift-independent, efficiency. We introduce a new self-consistent treatment of the halo star formation history, which allows us to make predictions at z > 10 (lookback time ?500 Myr), when growth is rapid. With a calibration at a single redshift to set the stellar-to-halo mass ratio, and no further degrees of freedom, our model captures the evolution of the UV LF over all available observations (0 ? z ? 10). The significant drop in luminosity density of currently detectable galaxies beyond z ? 8 is explained by a shift of star formation toward less massive, fainter galaxies. Assuming that star formation proceeds down to atomic cooling halos, we derive a reionization optical depth ? ={0.056}-0.010+0.007, fully consistent with the latest Planck measurement, implying that the universe is fully reionized at z={7.84}-0.98+0.65. In addition, our model naturally produces smoothly rising star formation histories for galaxies with L ? L* in agreement with observations and hydrodynamical simulations. Before the epoch of reionization at z > 10 we predict the LF to remain well-described by a Schechter function, but with an increasingly steep faint-end slope (? ? ?3.5 at z ? 16). Finally, we construct forecasts for surveys with James Webb Space Telescope (JWST) and Wide-field Infrared Survey Telescope (WFIRST) and predict that galaxies out to z ? 14 will be observed. Galaxies at z > 15 will likely be accessible to JWST and WFIRST only through the assistance of strong lensing magnification.

  2. Constraining the minimum luminosity of high redshift galaxies through gravitational lensing

    International Nuclear Information System (INIS)

    We simulate the effects of gravitational lensing on the source count of high redshift galaxies as projected to be observed by the Hubble Frontier Fields program and the James Webb Space Telescope (JWST) in the near future. Taking the mass density profile of the lensing object to be the singular isothermal sphere (SIS) or the Navarro-Frenk-White (NFW) profile, we model a lens residing at a redshift of zL = 0.5 and explore the radial dependence of the resulting magnification bias and its variability with the velocity dispersion of the lens, the photometric sensitivity of the instrument, the redshift of the background source population, and the intrinsic maximum absolute magnitude (Mmax) of the sources. We find that gravitational lensing enhances the number of galaxies with redshifts z?> 13 detected in the angular region ?E/2 ? ? ? 2?E (where ?E is the Einstein angle) by a factor of ? 3 and 1.5 in the HUDF (df/d?0 ? 9 nJy) and medium-deep JWST surveys (df/d?0 ? 6 nJy). Furthermore, we find that even in cases where a negative magnification bias reduces the observed number count of background sources, the lensing effect improves the sensitivity of the count to the intrinsic faint-magnitude cut-off of the Schechter luminosity function. In a field centered on a strong lensing cluster, observations of z?> 6 and z?> 13 galaxies with JWST can be used to infer this cut-off magnitude for values as faint as Mmax ? -14.4 and -16.1 mag (Lmin ? 2.5 × 1026 and 1.2 × 1027 erg s?1 Hz?1) respectively, within the range bracketed by existing theoretical models. Gravitational lensing may therefore offer an effective way of constraining the low-luminosity cut-off of high-redshift galaxies

  3. Perfomance of novel and upgraded instrumentation for luminosity and beam conditions measurements in CMS

    CERN Document Server

    Leonard, Jessica Lynn

    2015-01-01

    The beam monitoring and luminosity systems of the CMS experiment are enhanced by several new and upgraded sub-detectors to match the challenges of the LHC operation and physics program at increased energy and higher luminosity. A dedicated pixelated luminosity telescope is installed for a fast and precise luminosity measurement. This detector measures coincidences between several three-layer telescopes of silicon pixel detectors to arrive at luminosity for each colliding LHC bunch pair. An upgraded fast beam conditions monitor measures the particle flux using single crystalline diamond sensors. It is equipped with a dedicated front-end ASIC produced in 130 nm CMOS technology. The excellent time resolution is used to separate collision products from machine induced background, thus serving as online luminosity measurement. A new beam-halo monitor at larger radius exploits Cerenkov light from fused silica to provide direction sensitivity and excellent time resolution to separate incoming and outgoing particles....

  4. Measurement of the luminosity in the ZEUS experiment at HERA II

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L.; Bold, T. [AGH Univ. of Science and Technology, Cracow (Poland); Andruszkow, J. [Polish Academy of Sciences, Cracow (Poland). Inst. of Nuclear Physics] [and others

    2013-06-15

    The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung. In 2001 the HERA collider was upgraded for operation at higher luminosity. At the same time the luminosity-measuring system of the ZEUS experiment was modified to tackle the expected higher photon rate and synchrotron radiation. The existing lead-scintillator calorimeter was equipped with radiation hard scintillator tiles and shielded against synchrotron radiation. In addition, a magnetic spectrometer was installed to measure the luminosity independently using photons converted in the beam-pipe exit window. The redundancy provided a reliable and robust luminosity determination with a systematic uncertainty of 1.7%. The experimental setup, the techniques used for luminosity determination and the estimate of the systematic uncertainty are reported.

  5. L1Track: a fast Level 1 track trigger for the ATLAS High Luminosity Upgrade

    CERN Document Server

    Cerri, Alessandro

    2015-01-01

    With the planned high-luminosity upgrade of the LHC (HL-LHC), the ATLAS detector will see its collision rate increase by approximately a factor of 5 with respect to the current LHC operation. The earliest hardware based ATLAS trigger stage ("Level 1") will have to provide an higher rejection factor in a more difficult environment: a new improved Level 1 trigger architecture is under study, which includes the possibility of extracting with low latency and hight accuracy tracking information on time for the decision taking process. The expected trigger rates at HL-LHC and the available latency are the key ingredients that will drive the new design. The Level 1 track trigger (L1Track) design requires substantial modification of the ATLAS silicon detector readout philosophy: a precursor of the potential merging of detector and trigger architectures in the future silicon detectors at particle colliders. We will discuss potential approaches that are being actively considered to fulfil the demanding HL-LHC constrain...

  6. Nearby Galaxies in the 2micron All Sky Survey I. K-band Luminosity Functions

    OpenAIRE

    Devereux, Nick; S. P. Willner; Ashby, M. L. N.; C.N.A. Willmer; Hriljac, Paul

    2009-01-01

    Differential K-band luminosity functions (LFs) are presented for a complete sample of 1613 nearby bright galaxies segregated by visible morphology. The LF for late-type spirals follows a power law that rises towards low luminosities whereas the LFs for ellipticals, lenticulars and bulge-dominated spirals are peaked and decline toward both higher and lower luminosities. Each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall ...

  7. The lag and duration-luminosity relations of gamma-ray burst pulses

    OpenAIRE

    Boci, S.; M Hafizi; Mochkovitch, R.

    2011-01-01

    Relations linking the temporal or/and spectral properties of the prompt emission of gamma-ray bursts (hereafter GRBs) to the absolute luminosity are of great importance as they both constrain the radiation mechanisms and represent potential distance indicators. Here we discuss two such relations: the lag-luminosity relation and the newly discovered duration-luminosity relation of GRB pulses. We aim to extend our previous work on the origin of spectral lags, using the duratio...

  8. The number, luminosity, and mass density of spiral galaxies as a function of surface brightness

    CERN Document Server

    McGaugh, S S

    1995-01-01

    I give analytic expressions for the relative number, luminosity, and mass density of disc galaxies as a function of surface brightness. These surface brightness distributions are asymmetric, with long tails to lower surface brightnesses. This asymmetry induces systematic errors in most determinations of the galaxy luminosity function. Galaxies of low surface brightness exist in large numbers, but the additional contribution to the integrated luminosity density is modest, probably 10 -- 30\\%.

  9. The Effects of Accretion Luminosity upon Fragmentation in the Early Universe

    OpenAIRE

    Smith, Rowan J.; Glover, Simon C. O.; Clark, Paul C.; Greif, Thomas; Klessen, Ralf S.

    2011-01-01

    We introduce a prescription for the luminosity from accreting protostars into smoothed particle hydrodynamics simulation, and apply the method to simulations of five primordial minihalos generated from cosmological initial conditions. We find that accretion luminosity delays fragmentation within the halos, but does not prevent it. In halos that slowly form a low number of protostars, the accretion luminosity can reduce the number of fragments that are formed before the proto...

  10. The Herschel ATLAS: Evolution of the 250 Micrometer Luminosity Function Out to z = 0.5

    Science.gov (United States)

    Dye, S.; Dunne, L.; Eales, S.; Smith, D. J. B.; Amblard, A.; Auld, R.; Baes, M.; Baldry, I. K.; Bamford, S.; Blain, A. W.; Bonfield, D. G.; Bremer, M.; Burgarella, D.; Buttiglione, S.; Cameron, E.; Cava, A.; Clements, D. L.; Cooray, A.; Croom, S.; Dariush, A.; de Zotti, G.; Driver, S.; Dunlop, J. S.; Frayer, D.; Leeuw, L.

    2010-01-01

    We have determined the luminosity function of 250 micrometer-selected galaxies detected in the approximately equal to 14 deg(sup 2) science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 micrometer luminosity density out to z = 0.2 where it is 3.6(sup +1.4) (sub -0.9) times higher than the local value.

  11. Luminosities of H alpha emitting regions in a pair of interacting galaxies in the Bootes void

    Science.gov (United States)

    Weistrop, D.; Hintzen, P.; Kennicutt, R.; Liu, C.; Lowenthal, J.; Cheng, K.-P.; Oliversen, R.; Woodgate, B.

    1993-01-01

    Luminosities of H alpha emission from a pair of interacting galaxies in the low density environment of the Bootes void are presented. CG 692 (IRAS 1519+5050) has an H alpha luminosity of 2 x 10(exp 42) ergs s(exp -1), indicating a star formation rate of 18.4 solar mass yr(exp -1). Individual extranuclear H alpha regions have luminosities of approximately 10(exp 40) ergs s(exp -1). These luminosities are similar to those found for H II regions in bright, late-type galaxies in more densely populated parts of the Universe.

  12. Energy and Beam-Offset dependence of the Luminosity weighted depolarization for CLIC

    CERN Document Server

    Esberg, Jakob; Uggerhoj, Ulrik; Dalena, Barbara

    2011-01-01

    We report on simulations of e+e- depolarization due to beam-beam effects. These effects are studied for CLIC at 3 TeV, using GUINEA PIG++. We find a strong energy dependence of the luminosity weighted depolarization. In the luminosity peak at CLIC the total luminosity weighted depolarization remains below the one per-mil level. The effect of a vertical offset on the energy dependent depolarization is investigated. The depolarization in the luminosity peak remains below per-cent level even for 5sy offsets.

  13. THE DEMOGRAPHICS OF BROAD-LINE QUASARS IN THE MASS-LUMINOSITY PLANE. I. TESTING FWHM-BASED VIRIAL BLACK HOLE MASSES

    International Nuclear Information System (INIS)

    We jointly constrain the luminosity function (LF) and black hole mass function (BHMF) of broad-line quasars with forward Bayesian modeling in the quasar mass-luminosity plane, based on a homogeneous sample of ?58, 000 Sloan Digital Sky Survey (SDSS) Data Release 7 quasars at z ? 0.3-5. We take into account the selection effect of the sample flux limit; more importantly, we deal with the statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, as well as potential luminosity-dependent biases of these mass estimates. The LF is tightly constrained in the regime sampled by SDSS and makes reasonable predictions when extrapolated to ?3 mag fainter. Downsizing is seen in the model LF. On the other hand, we find it difficult to constrain the BHMF to within a factor of a few at z ?> 0.7 (with Mg II and C IV-based virial BH masses). This is mainly driven by the unknown luminosity-dependent bias of these mass estimators and its degeneracy with other model parameters, and secondly driven by the fact that SDSS quasars only sample the tip of the active BH population at high redshift. Nevertheless, the most likely models favor a positive luminosity-dependent bias for Mg II and possibly for C IV, such that at fixed true BH mass, objects with higher-than-average luminosities have overestimated FWHM-based virial masses. There is tentative evidence that downsizing also manifests itself in the active BHMF, and the BH mass density in broad-line quasars contributes an insignificant amount to the total BH mass density at all times. Within our model uncertainties, we do not find a strong BH mass dependence of the mean Eddington ratio, but there is evidence that the mean Eddington ratio (at fixed BH mass) increases with redshift.

  14. Distances to dense cores that contain very low luminosity objects

    Science.gov (United States)

    Maheswar, G.; Lee, C. W.; Dib, S.

    2011-12-01

    Aims: We estimate the distances to dense molecular cores that harbour very low luminosity objects (VeLLOs) detected by the Spitzer Space Telescope and attempt to confirm their VeLLO nature. Methods: The cloud distances are estimated using a near-IR photometric method. We use a technique that performs a spectral classification of stars lying towards the fields containing the clouds as either main-sequence stars or giants. In this technique, the observed (J - H) and (H - Ks) colours are dereddened simultaneously using trial values of AV and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of ?2 then yields the corresponding spectral type and AV for the star. The main-sequence stars, thus classified, are then utilized in an AV versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ~18%. Results: We estimate distances to seven cloud cores, IRAM 04191, L1521F, BHR 111, L328, L673-7, L1014, and L1148 using the above method. These clouds contain VeLLO candidates. The estimated distances to the cores are found to be 127 ± 25 pc (IRAM 04191), 136 ± 36 pc (L1521F), 355 ± 65 pc (BHR 111), 217 ± 30 pc (L328), 240 ± 45 pc (L673-7), 258 ± 50 pc (L1014), and 301 ± 55 pc (L1148). We re-evaluated the internal luminosities of the VeLLOs discovered in these seven clouds using the distances estimated from this work. Except for L1014 - IRS (Lint = 0.15 L?), all other VeLLO candidates are found to be consistent with the definition of a VeLLO (Lint ? 0.1 L?). In addition to the cores that harbour VeLLO candidates, we also obtained distances to the clouds L323, L675, L676, CB 188, L1122, L1152, L1155, L1157, and L1158, which are located in the directions of the above seven cores. Towards L1521F and L1148, we found evidence of multiple dust layers.

  15. Challenges on the high luminosity frontier of e+ e- factories

    International Nuclear Information System (INIS)

    For phi factories, tau-charm factories, and B factories to meet their respective luminosity goals, the circulating currents that typify e+ e- colliders must be raised an order of magnitude. At the same time the beam size at the interaction point must be decreased. The approaches to realizing these conditions include increasing the charge per bunch, increasing the number of bunches in the collider, increasing the crossing angle for rapid bunch separation, tilting the bunch with respect to the direction of motion at the interaction point (open-quotes crab-crossingclose quotes), and minimizing the ? function at the interaction point. The technological challenges implied by such strategies include the development of (1) novel rf-cavity designs to suppress higher order modes and to provide large rf-voltages for longitudinal focusing, (2) a new generation of powerful feedback electronics to control multi-bunch instabilities, and (3) vacuum chambers and pumping schemes suitable for operation with very high levels of synchrotron radiation. In high current colliders the design of the interaction region poses special problems of allowing rapid beam separation and avoiding excessive scattering of background radiation into the detector

  16. Distances to dense cores that contain Very Low Luminosity Objects

    CERN Document Server

    Maheswar, G; Dib, Sami

    2011-01-01

    The aim of the paper is to estimate distances to dense molecular cores that harbour Very Low Luminosity Objects (VeLLO) detected by Spitzer Space Telescope and to confirm their VeLLO nature. The cloud distances are estimated using near-IR photometric method. We use a technique that provides spectral classification of stars lying towards the fields containing the clouds into main sequence and giants. In this technique, the observed (J-H) and (H-Ks) colours are dereddened simultaneously using trial values of A_V and a normal interstellar extinction law. The best fit of the dereddened colours to the intrinsic colours giving a minimum value of chi^{2} then yields the corresponding spectral type and A_V for the star. The main sequence stars, thus classified, are then utilized in an A_V versus distance plot to bracket the cloud distances. The typical error in the estimation of distances to the clouds are found to be ~18%.We estimated distances to seven cloud cores, IRAM04191, L1521F, BHR111, L328, L673-7, L1014, an...

  17. Galaxy and Mass Assembly (GAMA): ugriz galaxy luminosity functions

    CERN Document Server

    Loveday, J; Baldry, I K; Driver, S P; Hopkins, A M; Peacock, J A; Bamford, S P; Liske, J; Bland-Hawthorn, J; Brough, S; Brown, M J I; Cameron, E; Conselice, C J; Croom, S M; Frenk, C S; Gunawardhana, M; Hill, D T; Jones, D H; Kelvin, L S; Kuijken, K; Nichol, R C; Parkinson, H R; Phillipps, S; Pimbblet, K A; Popescu, C C; Prescott, M; Robotham, A S G; Sharp, R G; Sutherland, W J; Taylor, E N; Thomas, D; Tuffs, R J; van Kampen, E; Wijesinghe, D

    2011-01-01

    Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fit over a range of more than ten magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue-plus-red sample, require double power-law Schechter functions to fit a dip in their LF faintward of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disk galaxies. We measure evolution of the galaxy LF over the redshift range 0.002 < z &...

  18. Galaxies with a Central Minimum in Stellar Luminosity Density

    CERN Document Server

    Lauer, T R; Richstone, D O; Tremaine, S; Bender, R; Bower, G; Dressler, A; Faber, S M; Filippenko, A V; Green, R; Grillmair, C J; Ho, L C; Kormendy, J; Magorrian, J; Pinkney, J C; Laine, S; Postman, M; Van der Marel, R P; Lauer, Tod R.; Gebhardt, Karl; Richstone, Douglas; Tremaine, Scott; Bender, Ralf; Bower, Gary; Dressler, Alan; Filippenko, Alexei V.; Green, Richard; Grillmair, Carl J.; Ho, Luis C.; Kormendy, John; Magorrian, John; Pinkney, Jason; Postman, Marc; Marel, Roeland P. van der

    2002-01-01

    We used HST WFPC2 images to identify six early-type galaxies with surface- brightness profiles that decrease inward over a limited range of radii near their centers. The implied luminosity density profiles of these galaxies have local minima interior to their core break radii. NGC 3706 harbors a high surface brightness ring of starlight with radius ~20 pc. Its central structure may be related to that in the double-nucleus galaxies M31 and NGC 4486B. NGC 4406 and NGC 6876 have nearly flat cores that on close inspection are centrally depressed. Colors for both galaxies imply that this is not due to dust absorption. The surface brightness distributions of both galaxies are consistent with stellar tori that are more diffuse than the sharply defined system in NGC 3706. The remaining three galaxies are the brightest cluster galaxies in A260, A347, and A3574. Color information is not available for these objects, but they strongly resemble NGC 4406 and NGC 6876 in their cores. The thin ring in NGC 3706 may have forme...

  19. Luminosity measurements with the LUCID detector in the ATLAS experiment

    CERN Document Server

    Valentinetti, Sara

    La misura della luminosità è un obiettivo importante per tutta la fisica del modello standard e per la scoperta di nuova fisica, poiché è legata alla sezione d'urto (?) e al rate di produzione (R) di un determinato processo dalla relazione L = R*?. Nell'eserimento ATLAS a LHC è installato un monitor di luminosità dedicato chiamato LUCID (Luminosity measurements Using Cherenkov Integrating Detector). Grazie ai dati acquisiti durante il 2010 la valutazione off-line delle performances del LUCID e l'implementazione di controlli on-line sulla qualità dei dati raccolti è stata possibile. I dati reali sono stati confrontati con i dati Monte Carlo e le simulazioni sono state opportunamente aggiustate per ottimizzare l'accordo tra i due. La calibrazione della luminosità relativa che permette di ottenere una valutazione della luminosità assoluta è stata possibile grazie ai cosiddetti Van der Meer scan, grazie ai quale è stata ottenuta una precisione dell'11%. L'analisi della fisica del decadimento della Z...

  20. On the perturbation of the luminosity distance by peculiar motions

    CERN Document Server

    Kaiser, Nick

    2014-01-01

    We consider some aspects of the perturbation to the luminosity distance $d(z)$ that are of relevance for SN1a cosmology and for future peculiar velocity surveys at non-negligible redshifts. 1) Previous work has shown that the correction to the lowest order perturbation $\\delta d / d = -\\delta v / c z$ has the peculiar characteristic that it appears to depend on the absolute state of motion of sources, rather than on their motion relative to that of the observer. The resolution of this apparent violation of the equivalence principle is that it is necessary to allow for evolution of the velocities with time, and also, when considering perturbations on the scale of the observer-source separation, to include the gravitational redshift effect. We provide an expression for $\\delta d / d$ that provides a physically consistent way to compute the impact of peculiar motions for SN1a cosmology and peculiar velocity surveys. 2) We then calculate the perturbation to the redshift as a function of source flux density, which...

  1. The Luminosity Function of Low-Redshift Abell Galaxy Clusters

    CERN Document Server

    Barkhouse, Wayne A; López-Cruz, Omar

    2007-01-01

    We present the results from a survey of 57 low-redshift Abell galaxy clusters to study the radial dependence of the luminosity function (LF). The dynamical radius of each cluster, r200, was estimated from the photometric measurement of cluster richness, Bgc. The shape of the LFs are found to correlate with radius such that the faint-end slope, alpha, is generally steeper on the cluster outskirts. The sum of two Schechter functions provides a more adequate fit to the composite LFs than a single Schechter function. LFs based on the selection of red and blue galaxies are bimodal in appearance. The red LFs are generally flat for -22 -18. The blue LFs contain a larger contribution from faint galaxies than the red LFs. The blue LFs have a rising faint-end component (alpha ~ -1.7) for M_Rc > -21, with a weaker dependence on radius than the red LFs. The dispersion of M* was determined to be 0.31 mag, which is comparable to the median measurement uncertainty of 0.38 mag. This suggests that the bright-end of the LF is...

  2. The slope of the GRB Variability/Peak Luminosity Correlation

    CERN Document Server

    Guidorzi, C; Montanari, E; Rossi, F; Amati, L; Gomboc, A; Mundell, C G

    2006-01-01

    From a sample of 32 GRBs with known redshift (Guidorzi et al. 2005) and then a sample of 551 BATSE GRBs with derived pseudo-redshift (Guidorzi 2005), the time variability/peak luminosity correlation (V vs. L) found by Reichart et al. (2001) was tested. For both samples the correlation is still found but less relevant due to a much higher spread of the data. Assuming a straight line in the logL-logV plane (logL = m logV + b), as done by Reichart et al., the slope was found lower than that derived by Reichart et al.: m = 1.3_{-0.4}^{+0.8} (Guidorzi et al. 2005), m = 0.85 +- 0.02 (Guidorzi 2005), to be compared with m = 3.3^{+1.1}_{-0.9} (Reichart et al. 2001). Reichart & Nysewander (2005) attribute the different slope to the fact we do not take into account in the fit the variance of the sample, and demonstrate that, using the method by Reichart (2001), the data set of Guidorzi et al. (2005) in logL-logV plane is still well described with slope m = 3.4^{+0.9}_{-0.6}. Here we compare the results of two metho...

  3. Jet and disk luminosities in tidal disruption events

    CERN Document Server

    Piran, Tsvi; Tchekhovskoy, Alexander

    2015-01-01

    Tidal disruption events (TDE) in which a star is devoured by a massive black hole at a galac- tic center pose a challenge to our understanding of accretion processes. Within a month the accretion rate reaches super-Eddington levels. It then drops gradually over a time scale of a year to sub-Eddington regimes. The initially geometrically thick disk becomes a thin one and eventually an ADAF at very low accretion rates. As such, TDEs explore the whole range of accretion rates and configurations. A challenging question is what the corresponding light curves of these events are. We explore numerically the disk luminosity and the conditions within the inner region of the disk using a fully general relativistic slim disk model. Those conditions determine the magnitude of the magnetic field that engulfs the black hole and this, in turn, determines the Blandford-Znajek jet power. We estimate this power in two different ways and show that they are self-consistent. We find, as expected earlier from analytic argu- ments ...

  4. ATLAS ALFA—measuring absolute luminosity with scintillating fibres

    CERN Document Server

    Franz, S

    2009-01-01

    ALFA is a high-precision scintillating fibre tracking detector under construction for the absolute determination of the LHC luminosity at the ATLAS interaction point. This detector, mounted in so-called Roman Pots, will track protons elastically scattered under ?rad angles at IP1.In total there are four pairs of vertically arranged detector modules which approach the LHC beam axis to mm distance. Each detector module consists of ten layers of two times 64 scintillating fibres each (U and V planes). The fibres are coupled to 64 channels Multi-Anodes PhotoMultipliers Tubes read out by compact front-end electronics. Each detector module is complemented by so-called overlap detectors: Three layers of two times 30 scintillating fibres which will be used to measure the relative positioning of two vertically arranged main detectors. The total number of channels is about 15000. Conventional plastic scintillator tiles are mounted in front of the fibre detectors and will serve as trigger counter. The extremely restric...

  5. The dust grain size - stellar luminosity trend in debris discs

    CERN Document Server

    Pawellek, Nicole

    2015-01-01

    The cross section of material in debris discs is thought to be dominated by the smallest grains that can still stay in bound orbits despite the repelling action of stellar radiation pressure. Thus the minimum (and typical) grain size $s_\\text{min}$ is expected to be close to the radiation pressure blowout size $s_\\text{blow}$. Yet a recent analysis of a sample of Herschel-resolved debris discs showed the ratio $s_\\text{min}/s_\\text{blow}$ to systematically decrease with the stellar luminosity from about ten for solar-type stars to nearly unity in the discs around the most luminous A-type stars. Here we explore this trend in more detail, checking how significant it is and seeking to find possible explanations. We show that the trend is robust to variation of the composition and porosity of dust particles. For any assumed grain properties and stellar parameters, we suggest a recipe of how to estimate the "true" radius of a spatially unresolved debris disc, based solely on its spectral energy distribution. The r...

  6. Large-angle Bhabha scattering and luminosity at flavour factories

    International Nuclear Information System (INIS)

    The luminosity determination of electron-positron colliders operating in the region of low-lying hadronic resonances (Ecm?1-10 GeV), such as BEPC/BES, DAPHINE, KEKB, PEP-II and VEPP-2M, requires the precision calculation of the Bhabha process at large scattering angles. In order to achieve a theoretical accuracy at a few 0.1% level, the inclusion of radiative corrections is mandatory. The phenomenologically relevant effect of QED corrections is taken into account in the framework of the Parton Shower (PS) method, which is employed both for cross section calculation and event generation. To test the reliability of the approach, a benchmark calculation, including exact O(?) corrections and higher-order leading logarithmic contributions, is developed as well and compared in detail with the PS predictions. The effect of O(?) next-to-leading and higher-order leading corrections is investigated in the presence of realistic event selections for the Bhabha process at the PHI factories. A new Monte Carlo generator for data analysis (BABAYAGA) is presented, with an estimated accuracy of 0.5%. Possible developments aiming at improving its precision and range of applicability are discussed

  7. On the luminosity distance and the epoch of acceleration

    Science.gov (United States)

    Sutherland, Will; Rothnie, Paul

    2015-02-01

    Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift zacc ˜ 0.7. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known `turnover' in the SN distance residuals ?? relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, not the deceleration predicted by ? cold dark matter and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model (w = -1/3), and also remapping the z-axis to u = ln (1 + z); we outline a number of useful and intuitive properties of this presentation. We conclude that there are significant complementarities between SNe and baryon acoustic oscillations (BAOs): SNe offer high precision at low redshifts and give good constraints on the net amount of acceleration since z ˜ 0.7, but are weak at constraining zacc; while radial BAO measurements are probably superior for placing direct constraints on zacc.

  8. On the luminosity distance and the epoch of acceleration

    CERN Document Server

    Sutherland, Will

    2015-01-01

    Standard cosmological models based on general relativity (GR) with dark energy predict that the Universe underwent a transition from decelerating to accelerating expansion at a moderate redshift $z_{acc} \\sim 0.7$. Clearly, it is of great interest to directly measure this transition in a model-independent way, without the assumption that GR is the correct theory of gravity. We explore to what extent supernova (SN) luminosity distance measurements provide evidence for such a transition: we show that, contrary to intuition, the well-known "turnover" in the SN distance residuals $\\Delta\\mu$ relative to an empty (Milne) model does not give firm evidence for such a transition within the redshift range spanned by SN data. The observed turnover in that diagram is predominantly due to the negative curvature in the Milne model, {\\em not} the deceleration predicted by $\\Lambda$CDM and relatives. We show that there are several advantages in plotting distance residuals against a flat, non-accelerating model $(w = -1/3)$,...

  9. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    Energy Technology Data Exchange (ETDEWEB)

    Kryukova, E.; Megeath, S. T.; Allen, T. S. [Department of Physics and Astronomy, University of Toledo, Toledo, OH (United States); Gutermuth, R. A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Pipher, J. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Allen, L. E. [National Optical Astronomy Observatories, Tucson, AZ (United States); Myers, P. C. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Muzerolle, J. [Space Telescope Science Institute, Baltimore, MD (United States)

    2012-08-15

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 {mu}m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 {mu}m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L{sub Sun} and show a tail extending toward luminosities above 100 L{sub Sun }. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L{sub Sun }. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity functions to those predicted by models and find that our observed luminosity functions are best matched by models that invoke competitive accretion, although we do not find strong agreement between the high-mass SF clouds and any of the models.

  10. LUMINOSITY FUNCTIONS OF SPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

    We identify protostars in Spitzer surveys of nine star-forming (SF) molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. These clouds encompass a variety of SF environments, including both low-mass and high-mass SF regions, as well as dense clusters and regions of sparsely distributed star formation. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine near- and mid-infrared photometry from the Two Micron All Sky Survey and Spitzer to create 1-24 ?m spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities, we derive a relationship between bolometric luminosity, mid-IR luminosity (integrated from 1-24 ?m), and SED slope. Estimations of the bolometric luminosities for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high-mass SF clouds (Orion, Mon R2, and Cep OB3) peak near 1 L? and show a tail extending toward luminosities above 100 L?. The luminosity functions of the low-mass SF clouds (Serpens, Perseus, Ophiuchus, Taurus, Lupus, and Chamaeleon) do not exhibit a common peak, however the combined luminosity function of these regions peaks below 1 L?. Finally, we examine the luminosity functions as a function of the local surface density of young stellar objects. In the Orion molecular clouds, we find a significant difference between the luminosity functions of protostars in regions of high and low stellar density, the former of which is biased toward more luminous sources. This may be the result of primordial mass segregation, although this interpretation is not unique. We compare our luminosity functions to those predicted by models and find that our observed luminosity functions are best matched by models that invoke competitive accretion, although we do not find strong agreement between the high-mass SF clouds and any of the models.

  11. Ultra-faint ultraviolet galaxies at z ? 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    International Nuclear Information System (INIS)

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ? 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ? 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100× fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range –19.5 < M 1500 < –13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be ? = –1.74 ± 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M 1500 = –13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B – V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z ?) compared to their brighter counterparts (Z ?), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ? 2 is 4.31?0.60+0.68×1026 erg s–1 Hz–1 Mpc–3, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ? 2 (assuming a constant dust extinction correction of 4.2 over all luminosities and a Kroupa initial mass function) of 0.148?0.020+0.023 M ? yr–1 Mpc–3, significantly higher than previous determinations because of the additional population of fainter galaxies and the larger dust correction factors.

  12. Ultra-faint ultraviolet galaxies at z ? 2 behind the lensing cluster A1689: The luminosity function, dust extinction, and star formation rate density

    Energy Technology Data Exchange (ETDEWEB)

    Alavi, Anahita; Siana, Brian; Freeman, William R.; Dominguez, Alberto [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Richard, Johan [Centre de Recherche Astrophysique de Lyon, Université Lyon 1, 9 Avenue Charles André, F-69561 Saint Genis Laval Cedex (France); Stark, Daniel P.; Robertson, Brant [Department of Astronomy, Steward Observatory, University of Arizona, 933 North Cherry Avenue, Rm N204, Tucson, AZ 85721 (United States); Scarlata, Claudia [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Teplitz, Harry I.; Rafelski, Marc [Infrared Processing and Analysis Center, Caltech, Pasadena, CA 91125 (United States); Kewley, Lisa, E-mail: anahita.alavi@email.ucr.edu [Research School of Astronomy and Astrophysics, The Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia)

    2014-01-10

    We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ? 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z ? 3. Because of the unprecedented depth of the images and the large magnification provided by the lensing cluster, we detect galaxies 100× fainter than previous surveys at this redshift. After removing all multiple images, we have 58 galaxies in our sample in the range –19.5 < M {sub 1500} < –13 AB mag. Because the mass distribution of A1689 is well constrained, we are able to calculate the intrinsic sensitivity of the observations as a function of source plane position, allowing for accurate determinations of effective volume as a function of luminosity. We fit the faint-end slope of the luminosity function to be ? = –1.74 ± 0.08, which is consistent with the values obtained for 2.5 < z < 6. Notably, there is no turnover in the luminosity function down to M {sub 1500} = –13 AB mag. We fit the UV spectral slopes with photometry from existing Hubble optical imaging. The observed trend of increasingly redder slopes with luminosity at higher redshifts is observed in our sample, but with redder slopes at all luminosities and average reddening of (E(B – V)) = 0.15 mag. We assume the stars in these galaxies are metal poor (0.2 Z {sub ?}) compared to their brighter counterparts (Z {sub ?}), resulting in bluer assumed intrinsic UV slopes and larger derived values for dust extinction. The total UV luminosity density at z ? 2 is 4.31{sub ?0.60}{sup +0.68}×10{sup 26} erg s{sup –1} Hz{sup –1} Mpc{sup –3}, more than 70% of which is emitted by galaxies in the luminosity range of our sample. Finally, we determine the global star formation rate density from UV-selected galaxies at z ? 2 (assuming a constant dust extinction correction of 4.2 over all luminosities and a Kroupa initial mass function) of 0.148{sub ?0.020}{sup +0.023} M {sub ?} yr{sup –1} Mpc{sup –3}, significantly higher than previous determinations because of the additional population of fainter galaxies and the larger dust correction factors.

  13. Testing the gamma-ray burst variability/peak luminosity correlation on a Swift homogeneous sample

    OpenAIRE

    Rizzuto, D.; Guidorzi, C.; Romano, P.; Covino, S.; Campana, S.; Capalbi, M.; Chincarini, G.; Cusumano, G; Fugazza, D.; Mangano, V.; Moretti, A.; Perri, M; Tagliaferri, G.

    2007-01-01

    We test the gamma-ray burst correlation between temporal variability and peak luminosity of the $\\gamma$-ray profile on a homogeneous sample of 36 Swift/BAT GRBs with firm redshift determination. This is the first time that this correlation can be tested on a homogeneous data sample. The correlation is confirmed, as long as the 6 GRBs with low luminosity (

  14. Electron-electron luminosity in the Next Linear Collider -- a preliminary study

    International Nuclear Information System (INIS)

    In this paper, the authors discuss some operational aspects of electron-electron collisions at the Next Linear Collider (NLC) and estimate the luminosity attainable in such a machine. They also consider the use of two future technologies which could simplify the operation and improve the luminosity in an e-e- collider: polarized rf guns and plasma lenses

  15. A precise measurement of luminosity by TOPAZ forward calorimeter at TRISTAN

    International Nuclear Information System (INIS)

    A precise measurement of luminosity with the TOPAZ forward calorimeter at TRISTAN by tagging small angle Bhabha events has been started. By using experimental data collected in 1990 the systematic errors of the measured luminosity were estimated in detail. After an intensive study, total systematic error was estimated to be at most 1.6%. (author)

  16. Far-infrared and accretion luminosities of the present-day active galactic nuclei

    CERN Document Server

    Matsuoka, Kenta

    2015-01-01

    We investigate the relation between star formation (SF) and black hole accretion luminosities, using a sample of 492 type-2 active galactic nuclei (AGNs) at z < 0.22, which are detected in the far-infrared (FIR) surveys with AKARI and Herschel. We adopt FIR luminosities at 90 and 100 um as SF luminosities, assuming the proposed linear proportionality of star formation rate with FIR luminosities. By estimating AGN luminosities from [OIII]5007 and [OI]6300 emission lines, we find a positive linear trend between FIR and AGN luminosities over a wide dynamical range. This result appears to be inconsistent with the recent reports that low-luminosity AGNs show essentially no correlation between FIR and X-ray luminosities, while the discrepancy is likely due to the Malmquist and sample selection biases. By analyzing the spectral energy distribution, we find that pure-AGN candidates, of which FIR radiation is thought to be AGN-dominated, show significantly low-SF activities. These AGNs hosted by low-SF galaxies are...

  17. SuperB: a Linear High-Luminosity B Factory

    International Nuclear Information System (INIS)

    This paper is based on the outcome of the activity that has taken place during the recent workshop on ''SuperB in Italy'' held in Frascati on November 11-12, 2005. The workshop was opened by a theoretical introduction of Marco Ciuchini and was structured in two working groups. One focused on the machine and the other on the detector and experimental issues.. The present status on CP is mainly based on the results achieved by BABAR and Belle. Establishment of the indirect CP violation in B sector in 2001 and of the direct CP violation in 2004 thanks to the success of PEP-II and KEKB e+e- asymmetric B Factories operating at the center of mass energy corresponding to the mass of the ?(4S ). With the two B Factories taking data, the Unitarity Triangle is now beginning to be over constrained by improving the measurements of the sides and now also of the angles ?, and ?. We are also in presence of the very intriguing results about the measurements of sin2? in the time dependent analysis of decay channels via penguin loops, where b ? s(bar s)s and b ? s(bar d)d. ? physics, in particular LFV search, as well as charm and ISR physics are important parts of the scientific program of a SuperB Factory. The physics case together with possible scenarios for the high luminosity SuperB Factory based on the concepts of the Linear Collider and the related experimental issues are discussed

  18. The Fast Tracker Architecture for the LHC baseline luminosity

    International Nuclear Information System (INIS)

    Hadron collider experiments search for extremely rare processes hidden in much larger background levels. Only a tiny fraction of the produced collisions can be stored on tape and an enormous real-time data reduction is needed. This requires massive computing power to minimize the on-line execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK) has been proposed for high quality track finding at very high rates (Level-1 output rates) for LHC experiments. FTK will use FPGA and ASIC devices in order to complement CPUs. FTK beats the combinatorial challenge with special associative memories, where parallelism is exploited to the maximum level. They compare the track detector hits to all pre-calculated track patterns at once. The system design is defined and proposed for high-luminosity studies including low-pT B physics and high-pT signatures for Level-2 selections: b-jets, tau-jets, and isolated stiff light leptons. We test FTK algorithms using Atlas full simulation with WH and Hqq events at 10-34 cm-2 s-1. The reconstruction quality is evaluated comparing FTK results with the tracking capability of an offline tracking algorithm. We show that similar resolutions and efficiencies are reached by FTK. The online use of the whole silicon tracker is necessary to obtain the low fake rate typical of the offline. We study the event timing inside the pipelined, data-driven FTK architecture. We compare different architectures to optimize the latency and hardware system size. (author)

  19. Cold Dust Emission from X-ray AGN in the SCUBA-2 Cosmology Legacy Survey: Dependence on Luminosity, Obscuration & AGN Activity

    CERN Document Server

    Banerji, Manda; Willott, C J; Geach, J E; Harrison, C M; Alaghband-Zadeh, S; Alexander, D M; Bourne, N; Coppin, K E K; Dunlop, J S; Farrah, D; Jarvis, M; Michalowski, M J; Page, M; Smith, D J B; Swinbank, A M; Symeonidis, M; Van der Werf, P P

    2015-01-01

    We study the 850um emission in X-ray selected AGN in the 2 sq-deg COSMOS field using new data from the SCUBA-2 Cosmology Legacy Survey. We find 19 850um bright X-ray AGN in a high-sensitivity region covering 0.89 sq-deg with flux densities of S850=4-10 mJy. The 19 AGN span the full range in redshift and hard X-ray luminosity covered by the sample - 0.71 X-ray AGN - S850=0.71+/-0.08mJy. We explore trends in the stacked 850um flux densities with redshift, finding no evolution in the average cold dust emission over the redshift range probed. For Type 1 AGN, there is no significant correlation between the stacked 850um flux and hard X-ray luminosity. However, in Type 2 AGN the stacked submm flux is a factor of 2 higher at high luminosities. When averaging over all X-ray luminosities, no significant differences are found in the stacked submm fluxes of Type 1 and Type 2 AGN as well as AGN separated on the basis of X-ray hardness ratios and optical-to-infrared colours. However, at log10(LX) >44.4, dependences in ave...

  20. The Relationship between Radio Luminosity and Core-Dominance Parameter for XBLs

    Indian Academy of Sciences (India)

    Yong-Xiang Wang; Y. Liu; Fei-Peng Pi; Jiang-He Yang

    2011-03-01

    In this work, we investigate the correlation between the luminosity and the core-dominance parameter for a sample of X-ray selected BL Lacertae objects (XBLs), and found that the extended luminosity is strongly anti-correlated with the core-dominance parameter while the core (or the total) luminosity is not correlated with the core-dominance parameter. If this is the case, then we can expect that the lower extended luminosity XBLs and their core luminosity is relatively higher. This can be explained by a relativistic beaming model since in this case, the viewing angle is smaller and the emissions dominate the extended emissions. Therefore, the anti-correlation is in fact the result of the relativistic beaming model.

  1. STATE TRANSITIONS IN BRIGHT GALACTIC X-RAY BINARIES: LUMINOSITIES SPAN BY TWO ORDERS OF MAGNITUDE

    International Nuclear Information System (INIS)

    Using X-ray monitoring observations with the All-Sky Monitor on board the Rossi X-Ray Timing Explorer and the Burst Alert Telescope on board the Swift, we are able to study the spectral state transitions occurred in about 20 bright persistent and transient black hole and neutron star binaries. We have confirmed that there is a correlation between the X-ray luminosity corresponding to the hard-to-soft transition and the X-ray luminosity of the following soft state. This correlation holds over a luminosity range spanning by 2 orders of magnitude, with no indication of a flux saturation or cutoff. We have also found that the transition luminosity correlates with the rate of increase in the X-ray luminosity during the rising phase of an outburst or flare, implying that the origin of the variation of the transition luminosity is associated with non-stationary accretion in both transient sources and persistent sources. The correlation between the luminosity corresponding to the end of the soft-to-hard transition and the peak luminosity of the preceding soft state is found insignificant. The results suggest that the hysteresis effect of spectral state transitions is primarily driven by non-stationary accretion when the mass accretion rate increases rather than the mass accretion rate decreases. Our results also imply that Galactic X-ray binaries can reach more luminous hard states during outbursts of higher luminosities and of similar rise timescales as those observed. Based on the correlations, we speculate that bright hard state beyond the Eddington luminosity will be observed in Galactic binaries in the next century. We also suggest that some ultra-luminous X-ray sources in nearby galaxies, which stay in the hard states during bright, short flares, harbor stellar-mass compact stars.

  2. Spin-orbit maps and electron spin dynamics for the luminosity upgrade project at HERA

    International Nuclear Information System (INIS)

    HERA is the high energy electron(positron)-proton collider at deutsches elektronen-synchrotron (DESY) in Hamburg. Following eight years of successful running, five of which were with a longitudinally spin polarized electron(positron) beam for the HERMES experiment, the rings have now been modified to increase the luminosity by a factor of about five and spin rotators have been installed for the H1 and ZEUS experiments. The modifications involve nonstandard configurations of overlapping magnetic fields and other aspects which have profound implications for the polarization. This thesis addresses the problem of calculating the polarization in the upgraded machine and the measures needed to maintain the polarization. A central topic is the construction of realistic spin-orbit transport maps for the regions of overlapping fields and their implementation in existing software. This is the first time that calculations with such fields have been possible. Using the upgraded software, calculations are presented for the polarization that can be expected in the upgraded machine and an analysis is made of the contributions to depolarization from the various parts of the machine. It is concluded that about 50% polarization should be possible. The key issues for tuning the machine are discussed. The last chapter deals with a separate topic, namely how to exploit a simple unitary model of spin motion to describe electron depolarization and thereby expose a misconception appearing in the literature. (orig.)

  3. X-Ray Binary Populations: The Luminosity Function of NGC1569

    CERN Document Server

    Belczynski, K; Zezas, A L; Fabbiano, G

    2004-01-01

    Using the population synthesis code StarTrack we construct the first synthetic X-ray binary populations for direct comparison with the X-ray luminosity function (XLF) of NGC 1569 observed with Chandra. Our main goal is to examine whether it is possible to reproduce the XLF shape with our models, given the current knowledge for the star-formation history of this starburst galaxy. We thus produce hybrid models meant to represent the two stellar populations: one old, metal-poor with continuous star-formation for 1.5 Gyr and another recent and metal-rich population. To examine the validity of the models we compare XLFs calculated for varying ages of the populations and varying relative weights for the star-formation rates in the two populations. We find that, for typical binary evolution parameters, it is indeed possible to quite closely match the observed XLF shape. The robust match is achieved for an age of the young population and a ratio of star formation rates in the two populations that are within factors o...

  4. Correlated Fluctuations in Luminosity Distance and the (Surprising) Importance of Peculiar Motion in Supernova Surveys

    CERN Document Server

    Hui, L; Hui, Lam; Greene, Patrick B.

    2005-01-01

    Large scale structure introduces two different kinds of errors in the luminosity distance estimates from standardizable candles such as supernovae Ia (SNe) - a Poissonian scatter for each SN and a coherent component due to correlated fluctuations between different SNe. Increasing the number of SNe helps reduce the first type of error but not the second. The coherent component has been largely ignored in forecasts of dark energy parameter estimation from upcoming SN surveys. For instance it is commonly thought, based on Poissonian considerations, that peculiar motion is unimportant, even for a low redshift SN survey such as the Nearby Supernova Factory (SNfactory; z = 0.03 - 0.08), which provides a useful anchor for future high redshift surveys by determining the SN zero-point. We show that ignoring coherent peculiar motion leads to an underestimate of the zero-point error by about a factor of 2, despite the fact that SNfactory covers almost half of the sky. More generally, there are four types of fluctuations...

  5. Interpreting broad emission-line variations II: Tensions between luminosity, characteristic size and responsivity

    CERN Document Server

    Goad, Michael R

    2015-01-01

    We investigate the variability behaviour of the broad Hb emission-line to driving continuum variations in the best-studied AGN NGC 5548. For a particular choice of BLR geometry, Hb surface emissivity based on photoionization models, and using a scaled version of the 13 yr optical continuum light curve as a proxy for the driving ionizing continuum, we explore several key factors that determine the broad emission line luminosity L, characteristic size R(RW), and variability amplitude (i.e., responsivity) eta, as well as the interplay between them. For fixed boundary models which extend as far as the hot-dust the predicted delays for Hb are on average too long. However, the predicted variability amplitude of Hb provides a remarkably good match to observations except during low continuum states. We suggest that the continuum flux variations which drive the redistribution in Hb surface emissivity F(r) do not on their own lead to large enough changes in R(RW) or eta(eff). We thus investigate dust-bounded BLRs for w...

  6. On the local radio luminosity function of galaxies; 2, environmental dependences among late-type galaxies

    CERN Document Server

    Gavazzi, G

    1999-01-01

    Using new extensive radio continuum surveys at 1.4 GHz (FIRST and NVSS), we derive the distribution of the radio/optical and radio/NIR luminosity (RLF) of late-type (Sa-Irr) galaxies (mp<15.7) in 5 nearby clusters of galaxies: A262, Cancer, A1367, Coma and Virgo. With the aim of discussing possible environmental dependences of the radio properties, we compare these results with those obtained for relatively isolated objects in the Coma supercluster. We find that the RLF of Cancer, A262 and Virgo are consistent with that of isolated galaxies. Conversely we confirm earlier claims that galaxies in A1367 and Coma have their radio emissivity enhanced by a factor of 5 with respect to isolated objects. We discuss this result in the framework of the dynamical pressure suffered by galaxies in motion through the intra-cluster gas (ram-pressure). We find that the radio excess is statistically larger for galaxies in fast transit motion. This is coherent with the idea that enhanced radio continuum activity is associate...

  7. Characterization of new ATLAS pixel Front-End prototype for upgraded luminosity

    International Nuclear Information System (INIS)

    Around the year 2012, a first upgrade to the Large Hadron Collider (LHC) is scheduled which should enhance the luminosity by a factor 2-3. To cope with the increased hit rate, the Front-End of the ATLAS innermost pixel detector layer needs to be replaced. A new Front-End chip, called FE-I4, is presently under development in several laboratories around the world. FE-I4 is designed to cope with the higher hit rate and has an enhanced radiation tolerance. In the process of developing FE-I4, an intermediate test chip (FEI4-proto1) has been designed and produced in a 130 nm technology. Several independent blocks are implemented on this chip. The main block is an array of 61 by 14 pixel cells with associated configuration logic, bias circuits and DACs as needed for the new ATLAS pixel FE. To test this chip, a test setup consisting of two PCBs has been developed. The first PCB carries the FEI4-proto1 and routes the designated signals and supply voltages to the chip. The second PCB is a master FPGA board to control the FE, with a USB interface to connect to a PC and provide a user friendly interface. The hardware, software and firmware were developed in Bonn. Using this setup, the behavior and the characteristics of the new blocks were tested to feedback the designers of the FE-I4 and optimize the new chip

  8. The galaxy luminosity function in groups and clusters: the faint-end upturn and the connection to the field luminosity function

    CERN Document Server

    Lan, Ting-Wen; Mo, Houjun

    2015-01-01

    We characterize the luminosity functions of galaxies residing in $z\\sim0$ groups and clusters over the broadest ranges of luminosity and mass reachable by the Sloan Digital Sky Survey. Our measurements cover four orders of magnitude in luminosity, down to about $M_r=-12$ mag or $L=10^7\\,L_\\odot$, and three orders of magnitude in halo mass, from $10^{12}$ to $10^{15} \\, {\\rm M}_\\odot$. We find a characteristic scale, $M_r\\sim-18$ mag or $L\\sim10^9\\, L_\\odot$, below which the slope of the luminosity function becomes systematically steeper. This trend is present for all halo masses and originates mostly from red satellite galaxies. The ubiquitous presence of this faint-end upturn suggests that it is formation, rather than halo-specific environmental effect, that plays a major role in regulating the stellar masses of faint satellites. We show that the observed luminosity functions of satellite galaxies can be described in a simple manner by a double Schechter function with amplitudes scaling with halo mass over t...

  9. LUMINOSITY FUNCTIONS OF LMXBs IN CENTAURUS A: GLOBULAR CLUSTERS VERSUS THE FIELD

    International Nuclear Information System (INIS)

    We study the X-ray luminosity function (XLF) of low-mass X-ray binaries (LMXB) in the nearby early-type galaxy Centaurus A, concentrating primarily on two aspects of binary populations: the XLF behavior at the low-luminosity limit and the comparison between globular cluster and field sources. The 800 ksec exposure of the deep Chandra VLP program allows us to reach a limiting luminosity of ?8 x 1035 erg s-1, about ?2-3 times deeper than previous investigations. We confirm the presence of the low-luminosity break of the overall LMXB XLF at log(LX ) ? 37.2-37.6, below which the luminosity distribution follows a dN/d(ln L) ? const law. Separating globular cluster and field sources, we find a statistically significant difference between the two luminosity distributions with a relative underabundance of faint sources in the globular cluster population. This demonstrates that the samples are drawn from distinct parent populations and may disprove the hypothesis that the entire LMXB population in early-type galaxies is created dynamically in globular clusters. As a plausible explanation for this difference in the XLFs, we suggest an enhanced fraction of helium-accreting systems in globular clusters, which are created in collisions between red giants and neutron stars. Due to the four times higher ionization temperature of He, such systems are subject to accretion disk instabilities at ?20 times higher mass accretion rate and, therefore, are not observed as persistent sources at low luminosities.

  10. The total infrared luminosity may significantly overestimate the star formation rate of recently quenched galaxies

    CERN Document Server

    Hayward, Christopher C; Ashby, Matthew L N; Fazio, Giovanni; Hernquist, Lars; Martínez-Galarza, Juan Rafael; Noeske, Kai; Smith, Howard A; Wuyts, Stijn; Zezas, Andreas

    2014-01-01

    The total infrared (IR) luminosity is very useful for estimating the star formation rate (SFR) of galaxies, but converting the IR luminosity into an SFR relies on assumptions that do not hold for all galaxies. We test the effectiveness of the IR luminosity as an SFR indicator by applying it to synthetic spectral energy distributions generated from three-dimensional hydrodynamical simulations of isolated disc galaxies and galaxy mergers. In general, the SFR inferred from the IR luminosity agrees well with the true instantaneous SFR of the simulated galaxies. However, for the major mergers in which a strong starburst is induced, the SFR inferred from the IR luminosity can overestimate the instantaneous SFR during the post-starburst phase by greater than two orders of magnitude. Even though the instantaneous SFR decreases rapidly after the starburst, the stars that were formed in the starburst remain dust-obscured and thus produce significant IR luminosity. Consequently, use of the IR luminosity as an SFR indica...

  11. STELLAR VELOCITY DISPERSION MEASUREMENTS IN HIGH-LUMINOSITY QUASAR HOSTS AND IMPLICATIONS FOR THE AGN BLACK HOLE MASS SCALE

    Energy Technology Data Exchange (ETDEWEB)

    Grier, C. J.; Martini, P.; Peterson, B. M.; Pogge, R. W.; Zu, Y. [Department of Astronomy, Ohio State University, 140 W 18th Avenue, Columbus, OH 43210 (United States); Watson, L. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Dasyra, K. M. [Observatoire de Paris, LERMA (CNRS:UMR8112), 61 Avenue de l' Observatoire, F-75014, Paris (France); Dietrich, M. [Department of Physics and Astronomy, Ohio University, Athens, OH 45601 (United States); Ferrarese, L. [Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria BV V9E 2E7 (Canada)

    2013-08-20

    We present new stellar velocity dispersion measurements for four luminous quasars with the Near-Infrared Integral Field Spectrometer instrument and the ALTAIR laser guide star adaptive optics system on the Gemini North 8 m telescope. Stellar velocity dispersion measurements and measurements of the supermassive black hole (BH) masses in luminous quasars are necessary to investigate the coevolution of BHs and galaxies, trace the details of accretion, and probe the nature of feedback. We find that higher-luminosity quasars with higher-mass BHs are not offset with respect to the M{sub BH}-{sigma}{sub *} relation exhibited by lower-luminosity active galactic nuclei (AGNs) with lower-mass BHs, nor do we see correlations with galaxy morphology. As part of this analysis, we have recalculated the virial products for the entire sample of reverberation-mapped AGNs and used these data to redetermine the mean virial factor (f) that places the reverberation data on the quiescent M{sub BH}-{sigma}{sub *} relation. With our updated measurements and new additions to the AGN sample, we obtain (f) = 4.31 {+-} 1.05, which is slightly lower than, but consistent with, most previous determinations.

  12. The $z < 1.2$ optical luminosity function from a sample of $\\sim410 \\, 000$ galaxies in bootes

    CERN Document Server

    Beare, Richard A; Pimbblet, Kevin A; Bian, Fuyan; Lin, Yen-Ting

    2015-01-01

    Using a sample of ~410 000 galaxies to depth I_AB = 24 over 8.26 deg^2 in the Bootes field (~10 times larger than z~1 luminosity function studies in the prior literature), we have accurately measured the evolving B-band luminosity function of red galaxies at z<1.2 and blue galaxies at z<1.0. In addition to the large sample size, we utilise photometry that accounts for the varying angular sizes of galaxies, photometric redshifts verified with spectroscopy, and absolute magnitudes that should have very small random and systematic errors. Our results are consistent with the migration of galaxies from the blue cloud to the red sequence as they cease to form stars, and with downsizing in which more massive and luminous blue galaxies cease star formation earlier than fainter less massive ones. Comparing the observed fading of red galaxies with that to be expected from passive evolution alone, we find that the stellar mass contained within the red galaxy population has increased by a factor of ~3.6 from z~1.1 ...

  13. The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei From Reverberation Mapping and Hubble Space Telescope Imaging

    DEFF Research Database (Denmark)

    Bentz, Misty C.; Peterson, Bradley M.

    2009-01-01

    We investigate the relationship between black hole mass and bulge luminosity for active galactic nuclei (AGNs) with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope of the relationship for AGNs is 0.76-0.85 with an uncertainty of ~0.1, somewhat shallower than the M BH vprop L 1.0±0.1 relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This difference is somewhat perplexing, as the AGN black hole masses include an overall scaling factor that brings the AGN M BH-ssstarf relationship into agreement with that of quiescent galaxies. We discuss biases that may be inherent to the AGN and quiescent galaxy samples and could cause the apparent inconsistency in the forms of their M BH-L bulge relationships. Recent work by Graham, however, presents a similar slope of ~0.8 for the quiescent galaxies and may bring the relationship for AGNs and quiescent galaxies into agreement.

  14. Luminosity Loss due to Beam Distortion and the Beam-Beam Instability

    CERN Document Server

    Wu, Juhao; Raubenheimer, Tor O; Seryi, Andrei; Sramek, Christopher K

    2005-01-01

    In a linear collider, sources of emittance dilution such as transverse wakefields or dispersive errors will couple the vertical phase space to the longitudinal position within the beam (the so-called ?banana effect'). When the Intersection Point (IP) disruption parameter is large, these beam distortions will be amplified by a single bunch kink instability which will lead to luminosity loss. We study this phenomena both analytically using linear theory and via numerical simulation. In particular, we examine the dependence of the luminosity loss on the wavelength of the beam distortions and the disruption parameter. This analysis may prove useful when optimizing the vertical disruption parameter for luminosity operation with given beam distortions.

  15. Experimental demonstration of interaction region beam waist position knob for luminosity leveling

    International Nuclear Information System (INIS)

    In this paper, we report the experimental implementation of the model-dependent control of the interaction region beam waist position (s* knob) at Relativistic Heavy Ion Collider (RHIC). The s* adjustment provides an alternative way of controlling the luminosity and is only known method to control the luminosity and reduce the pinch effect of the future eRHIC. In this paper, we will first demonstrate the effectiveness of the s* knob in luminosity controlling and its application in the future electron ion collider, eRHIC, followed by the detail experimental demonstration of such knob in RHIC.

  16. A High Luminosity e+e- Collider in the LHC tunnel to study the Higgs Boson

    OpenAIRE

    Blondel, Alain; Zimmermann, Frank

    2011-01-01

    We consider the possibility of a 120x120 GeV e+e- ring collider in the LHC tunnel. A luminosity of 10^34/cm2/s can be obtained with a luminosity life time of a few minutes. A high operation efficiency would require two machines: a low emittance collider storage ring and a separate accelerator injecting electrons and positrons into the storage ring to top up the beams every few minutes. A design inspired from the high luminosity b-factory design and from the LHeC design repor...

  17. Experimental demonstration of interaction region beam waist position knob for luminosity leveling

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Yue [Brookhaven National Lab. (BNL), Upton, NY (United States); Bai, Mei [Inst. fuer Kernphysik, Juelich (Germany). Inst. for Advanced Simulation; Duan, Zhe [Inst. of High Energy Physics, Beijing (China); Luo, Yun [Brookhaven National Lab. (BNL), Upton, NY (United States); Marusic, Aljosa [Brookhaven National Lab. (BNL), Upton, NY (United States); Robert-Demolaize, Guillaume [Brookhaven National Lab. (BNL), Upton, NY (United States); Shen, Xiaozhe [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-05-03

    In this paper, we report the experimental implementation of the model-dependent control of the interaction region beam waist position (s* knob) at Relativistic Heavy Ion Collider (RHIC). The s* adjustment provides an alternative way of controlling the luminosity and is only known method to control the luminosity and reduce the pinch effect of the future eRHIC. In this paper, we will first demonstrate the effectiveness of the s* knob in luminosity controlling and its application in the future electron ion collider, eRHIC, followed by the detail experimental demonstration of such knob in RHIC.

  18. Stacking the Invisibles: A Guided Search for Low-Luminosity Milky Way Satellites

    OpenAIRE

    B. Sesar; Banholzer, S. R.; Cohen, J. G.; Martin, N. F.; Grillmair, C. J.; Levitan, D.; R. R. Laher; Ofek, E. O.; Surace, J. A.; Kulkarni, S.R.; Prince, T. A.; Rix, H. -W.

    2014-01-01

    Almost every known low-luminosity Milky Way dwarf spheroidal (dSph) satellite galaxy contains at least one RR Lyrae star. Assuming that a fraction of distant (60 < d_{helio} < 100 kpc) Galactic halo RR Lyrae stars are members of yet to be discovered low-luminosity dSph galaxies, we perform a {\\em guided} search for these low-luminosity dSph galaxies. In order to detect the presence of dSph galaxies, we combine stars selected from more than 123 sightlines centered on RR Lyrae...

  19. A luminosity monitor for the A4 parity violation experiment at MAMI

    CERN Document Server

    Hammel, T; Baunack, S; Capozza, L; Diefenbach, J; Grimm, K; Imai, Y; Kabuss, E M; Kothe, R; Lee, J H; Lopes-Ginja, A; Maas, F E; Sanchez-Lorente, A; Schilling, E P; Stephan, G; Weinrich, C; Altarev, I S

    2006-01-01

    A water Cherenkov luminosity monitor system with associated electronics has been developed for the A4 parity violation experiment at MAMI. The detector system measures the luminosity of the hydrogen target hit by the MAMI electron beam and monitors the stability of the liquid hydrogen target. Both is required for the precise study of the count rate asymmetries in the scattering of longitudinally polarized electrons on unpolarized protons. Any helicity correlated fluctuation of the target density leads to false asymmetries. The performance of the luminosity monitor, investigated in about 2000 hours with electron beam, and the results of its application in the A4 experiment are presented.

  20. The GALEX UV luminosity function of the cluster of galaxies Abell 1367

    OpenAIRE

    Cortese, L; A. Boselli; Gavazzi, G; Iglesias-Paramo1, J.; Madore, B. F.; Barlow, T; Bianchi, L; Byun, Y. -I.; Donas, J; Forster, K; Friedman, P. G.; T. M. Heckman; Jelinsky, P; Lee, Y. -W.; Malina, R.

    2005-01-01

    We present the GALEX NUV (2310 A) and FUV (1530 A) galaxy luminosity functions of the nearby cluster of galaxies A1367 in the magnitude range -20.3< M_AB < -13.3. The luminosity functions are consistent with previous (~ 2 mag shallower) estimates based on the FOCA and FAUST experiments, but display a steeper faint-end slope than the GALEX luminosity function for local field galaxies. Using spectro-photometric optical data we select out star-forming systems from quiescent gal...

  1. The UV Galaxy Luminosity Function in the Local Universe from GALEX Data

    OpenAIRE

    Ted K. Wyder; Treyer, Marie A.; Milliard, Bruno; Schiminovich, David; Arnouts, Stéphane; Budavári, Tamás; Barlow, Tom A.; Bianchi, Luciana; Byun, Yong-Ik; Donas, José; Forster, Karl; Friedman, Peter G.; Heckman, Timothy M.; Jelinsky, Patrick N.; Lee, Young-Wook

    2004-01-01

    We present the results of a determination of the galaxy luminosity function at ultraviolet wavelengths at redshifts of $z=0.0-0.1$ from GALEX data. We determined the luminosity function in the GALEX FUV and NUV bands from a sample of galaxies with UV magnitudes between 17 and 20 that are drawn from a total of 56.73 deg^2 of GALEX fields overlapping the b_j-selected 2dF Galaxy Redshift Survey. The resulting luminosity functions are fainter than previous UV estimates and resul...

  2. Detector Developments for the High Luminosity LHC Era (1/4)

    CERN Document Server

    CERN. Geneva

    2010-01-01

    Calorimetry and Muon Spectrometers - Part I : In the first part of the lecture series, the motivation for a high luminosity upgrade of the LHC will be quickly reviewed together with the challenges for the LHC detectors. In particular, the plans and ongoing research for new calorimeter detectors will be explained. The main issues in the high-luminosity era are an improved radiation tolerance, natural ageing of detector components and challenging trigger and physics requirements. The new technological solutions for calorimetry at a high-luminosity LHC will be reviewed.

  3. Kinematics, Substructure and Luminosity-weighted Dynamics of Six Nearby Galaxy Groups

    CERN Document Server

    Firth, P; Jones, J B; Drinkwater, M J; Phillipps, S; Gregg, M D

    2006-01-01

    We have redefined group membership of six southern galaxy groups in the local universe (mean cz < 2000 km/s) based on new redshift measurements from our recently acquired Anglo-Australian Telescope 2dF spectra. For each group, we investigate member galaxy kinematics, substructure, luminosity functions and luminosity-weighted dynamics. Our calculations confirm that the group sizes, virial masses and luminosities cover the range expected for galaxy groups, except that the luminosity of NGC 4038 is boosted by the central starburst merger pair. We find that a combination of kinematical, substructural and dynamical techniques can reliably distinguish loose, unvirialised groups from compact, dynamically relaxed groups. Applying these techniques, we find that Dorado, NGC 4038 and NGC 4697 are unvirialised, whereas NGC 681, NGC 1400 and NGC 5084 are dynamically relaxed.

  4. Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z Surveys

    CERN Document Server

    Trenti, M

    2007-01-01

    We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the distribution of the galaxy number counts. This is obtained by means of analytic estimates via the two point correlation function in extended Press-Schechter theory as well as by using synthetic catalogs extracted from N-body cosmological simulations of structure formation. We adopt a simple luminosity - dark halo mass relation to investigate the environment effects on the fitting of the luminosity function. We show that in addition to variations of the normalization of the luminosity function, a steepening of its slope is also expected in underdense fields, similarly to what is observed within voids in the local universe. Therefore, to avoid introducing artificial biases, caution must be taken when attempting to correct for field underdensity, such as in the case of HST UDF i...

  5. The ATLAS liquid argon calorimeter high-voltage system: commissioning, optimisation and LHC relative luminosity measurement

    International Nuclear Information System (INIS)

    The main goals of the ATLAS scientific programme are the observation or exclusion of physics beyond the Standard Model (SM), as well as the measurement of production cross-sections of SM processes. In order to do so, it is important to measure the luminosity at the interaction point with great precision. The ATLAS luminosity is extracted using several detectors with varying efficiencies and acceptances. Different methods, such as inclusive - or coincidence - event counting and calorimeter integrated current measurements, are calibrated and cross-compared to provide the most accurate luminosity determination. In order to provide more cross-checks and a better control on the systematic uncertainties, an independent measurement using the liquid argon (LAr) forward calorimeter (FCal), based on the readout current of its high-voltage system, has been developed. This document describes how the LAr calorimeter high-voltage system has been installed and commissioned, as well as its application to a relative luminosity determination. (author)

  6. Analysis of luminosity distributions and shape parameters of strong gravitational lensing elliptical galaxies

    CERN Document Server

    Biernaux, J; Sluse, D; Chantry, V

    2015-01-01

    Luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as GALFIT or IMFITFITS and various PSF-determining methods have resulted in discrepant results. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half-light radius of the galaxy. Our half-light radius measurement method is based on an innovative sche...

  7. Semi-empirical model for optimising future heavy-ion luminosity of the LHC

    CERN Document Server

    Schaumann, M

    2014-01-01

    The wide spectrum of intensities and emittances imprinted on the LHC Pb bunches during the accumulation of bunch trains in the injector chain result in a significant spread in the single bunch luminosities and lifetimes in collision. Based on the data collected in the 2011 Pb-Pb run, an empirical model is derived to predict the single-bunch peak luminosity depending on the bunch’s position within the beam. In combination with this model, simulations of representative bunches are used to estimate the luminosity evolution for the complete ensemble of bunches. Several options are being considered to improve the injector performance and to increase the number of bunches in the LHC, leading to several potential injection scenarios, resulting in different peak and integrated luminosities. The most important options for after the long shutdown (LS) 1 and 2 are evaluated and compared.

  8. Luminosity measurement at LEP using the very small angle tagger of DELPHI

    International Nuclear Information System (INIS)

    In this thesis, the analysis of the luminosity measurement from Bhabha scattering within the polar angular region (5 to 7 mrad) covered by the Very Small Angle Tagger (VSAT) in the DELPHI experiment at LEP, is presented. Both by analytical integration and using Monte Carlo simulation, it is shown that the acceptance corrections to the detector can be reliably calculated, obtaining a relative luminosity measurement at the precision level of 0.1%. The absolute experimental error on the luminosity measurement is estimated to be 0.8%. Furthermore, measurement of the beam spot using the VSAT detector are described. The application of the relative luminosity measurement in the extraction of the hadronic lineshape parameters of the Z-particle is also presented

  9. High voltage monolithic active pixel sensors for the PANDA luminosity detector

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Tobias; Feldbauer, Florian; Jasinski, Prometeusz; Leithoff, Heinrich; Motzko, Christof; Fritsch, Miriam [Helmholtz-Institut Mainz and Institut fuer Kernphysik, Universitaet Mainz (Germany); Collaboration: PANDA-Collaboration

    2014-07-01

    The PANDA-Experiment will be part of the new FAIR accelerator center at Darmstadt, Germany. It is a fixed target experiment using a antiproton beam with very high resolution for precision measurements. For a variety of measurements like energy-scans the precise determination of the luminosity is needed. The luminosity detector will determine the luminosity by measuring the angular distribution of elastically scattered antiprotons very close to the beam axis (3-8 mrad). To reconstruct antiproton tracks four layers of thinned silicon sensors with smart pixel readout on chip (HV-MAPS) will be used. Those sensors are currently under development by the Mu3e-collaboration. In the talk the concept of the luminosity measurement is shortly introduced before a summary of the status of HV-MAP prototypes and recent test beam results are presented.

  10. Studies on the measurement of differential luminosity using Bhabha events at the International Linear Collider

    International Nuclear Information System (INIS)

    The International Linear Collider (ILC) is an electron-positron-collider with a variable center-of-mass energy ?(2) between 200 and 500 GeV. The small bunch sizes needed to reach the design luminosity of LPeak=2.1034 cm-2s-1 necessary for the physics goals of the ILC, cause the particles to radiate beamstrahlung during the bunch crossings. Beamstrahlung reduces the center-of-mass energy from its nominal value to the effective center-of-mass energy ?(2'). The spectrum of the effective center-of-mass energy ?(2') is the differential luminosity dL/d?(2'), which has to be known to precisely measure particle masses through threshold scans. The differential luminosity can be measured by using Bhabha events. The real differential luminosity is simulated by the GuineaPig software. The energy spectrum of the Bhabha events is measured by the detector and compared to the energy spectrum of Monte Carlo (MC) Bhabha events with a known differential luminosity given by an approximate parameterization. The parameterization is used to assign each MC event a weight. By re-weighting the events, until the energy spectra from the real and the MC Bhabha events match, the differential luminosity can be measured. The approximate parameterization of the differential luminosity is given by the Circe parameterization introduced by T. Ohl (1997), which does not include the correlation between the particle energies due to beamstrahlung. The Circe parameterization is extended to include the correlation and better describe the differential luminosity. With this new parameterization of the differential luminosity it is possible to predict the observed production cross section of a MC toy particle with a mass of 250 GeV/c2 to a precision better than 0.2%. Using the re-weighting fit with the extended parameterization also allows the measurement of the beam energy spreads of ?E=0.0014 for electrons and ?E= 0.0010 for positrons with a precision of a few percent. The total error from the measured differential luminosity and beam energy spreads on the mass of a toy particle measured in a production threshold scan is found to be 7 MeV/c2 for a 250 GeV/c2 particle, with an integrated luminosity of 5fb-1 per scanning point. (orig.)

  11. Studies on the measurement of differential luminosity using Bhabha events at the International Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Sailer, Andre Philippe

    2009-04-15

    The International Linear Collider (ILC) is an electron-positron-collider with a variable center-of-mass energy {radical}(2) between 200 and 500 GeV. The small bunch sizes needed to reach the design luminosity of L{sub Peak}=2.10{sup 34} cm{sup -2}s{sup -1} necessary for the physics goals of the ILC, cause the particles to radiate beamstrahlung during the bunch crossings. Beamstrahlung reduces the center-of-mass energy from its nominal value to the effective center-of-mass energy {radical}(2'). The spectrum of the effective center-of-mass energy {radical}(2') is the differential luminosity dL/d{radical}(2'), which has to be known to precisely measure particle masses through threshold scans. The differential luminosity can be measured by using Bhabha events. The real differential luminosity is simulated by the GuineaPig software. The energy spectrum of the Bhabha events is measured by the detector and compared to the energy spectrum of Monte Carlo (MC) Bhabha events with a known differential luminosity given by an approximate parameterization. The parameterization is used to assign each MC event a weight. By re-weighting the events, until the energy spectra from the real and the MC Bhabha events match, the differential luminosity can be measured. The approximate parameterization of the differential luminosity is given by the Circe parameterization introduced by T. Ohl (1997), which does not include the correlation between the particle energies due to beamstrahlung. The Circe parameterization is extended to include the correlation and better describe the differential luminosity. With this new parameterization of the differential luminosity it is possible to predict the observed production cross section of a MC toy particle with a mass of 250 GeV/c{sup 2} to a precision better than 0.2%. Using the re-weighting fit with the extended parameterization also allows the measurement of the beam energy spreads of {sigma}{sub E}=0.0014 for electrons and {sigma}{sub E}= 0.0010 for positrons with a precision of a few percent. The total error from the measured differential luminosity and beam energy spreads on the mass of a toy particle measured in a production threshold scan is found to be 7 MeV/c{sup 2} for a 250 GeV/c{sup 2} particle, with an integrated luminosity of 5fb{sup -1} per scanning point. (orig.)

  12. SPITZER observations of Abell 1763. III. The infrared luminosity function in different supercluster environments

    OpenAIRE

    Biviano, A.; Fadda, D; Durret, F.; Edwards, L. O. V.; Marleau, F.

    2011-01-01

    We determine the galaxy infrared (IR) luminosity function (LF) as a function of the environment in a supercluster at z=0.23, using optical, near-IR, and mid- to far-IR photometry, as well as redshifts from optical spectroscopy. We identify 467 supercluster members in a sample of 24-micron-selected galaxies, on the basis of their spectroscopic (153) and photometric (314) redshifts. IR luminosities, stellar masses and star formation rates (SFRs) are determined for supercluster...

  13. The RR Lyrae Star Period - K-band Luminosity Relation of the Globular Cluster M3

    OpenAIRE

    Butler, D. J.

    2003-01-01

    That the RR Lyrae star period -- K-band luminosity relation is a promising tool as a distance indicator in the Milky Way and Local Group of Galaxies is apparent on observational and theoretical grounds in the literature. Less clear is the sensitivity of the relation, and consequently the physics of horizontal branch stars, to differences in stellar environment. In this paper, the first measurement of the (fundamental) period -- K-band luminosity relation for the central regi...

  14. The bivariate K-band-submillimetre luminosity functions of the local HRS galaxy sample

    OpenAIRE

    Andreani, P.; Spinoglio, L.; A. Boselli; Ciesla, L.; Cortese, L.; Vio, R.; Baes, M.; Bendo, G. J.; de Looze, I.

    2014-01-01

    We study the relationship between the K-band and the sub-millimetre (submm) emissions of nearby galaxies by computing the bivariate K-band-submm luminosity function (BLF) of the Herschel Reference Survey (HRS), a volume-limited sample observed in submm with Hersche/SPIRE. We derive the BLF from the K-band and submm cumulative distributions using a copula method. Using the BLF allows us to derive the relationship between the luminosities on more solid statistical ground. The ...

  15. Determination of the integrated luminosity at HERA using elastic QED Compton events

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)

    2012-04-15

    A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep{yields}e{gamma}p. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3%. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process.

  16. Evidence for Luminosity Evolution of Long Gamma-ray Bursts in Swift Data

    OpenAIRE

    Salvaterra, R.; Guidorzi, C.; Campana, S.; Chincarini, G.; Tagliaferri, G.

    2008-01-01

    We compute the luminosity function (LF) and the formation rate of long gamma ray bursts (GRBs) by fitting the observed differential peak flux distribution obtained by the BATSE experiment in two different scenarios: i) the GRB luminosity evolves with redshift and ii) GRBs form preferentially in low-metallicity environments. In both cases, model predictions are consistent with the Swift number counts and with the number of detections at z>2.5 and z>3.5. To discriminate betwee...

  17. The BATSE-Swift luminosity and redshift distributions of short-duration GRBs

    OpenAIRE

    Guetta, Dafne; Piran, Tsvi

    2005-01-01

    We compare the luminosity function and rate inferred from the BATSE short hard bursts (SHBs) peak flux distribution with the redshift and luminosity distributions of SHBs observed by Swift/HETE II. While the Swift/HETE II SHB sample is incompatible with SHB population that follows the star formation rate, it is compatible with a SHB rate that reflect a distribution of delay times after the SFR. This would be the case if SHBs are associated with binary neutron star mergers. T...

  18. Abort Gap Cleaning tests performed on 13 October 2011 during luminosity operation

    CERN Document Server

    Boccardi, A; Jeff, A; Roncarolo, F; Höfle, W; Valuch, D; Kain, V; Goddard, B; Meddahi, M; Uythoven, J; Gianfelice-Wendt, E

    2012-01-01

    Following the abort gap cleaning tests performed on 7 October 2011 [1] additional tests were carried out on 13 October 2011 to further investigate the effects of the cleaning on the luminosity production. The abort gap cleaning parameters (strength and duration of the beam excitation kick) were varied and the cleaning effectiveness measured together with the change in luminosity. The outcome is summarised in this note.

  19. The Star Formation History of the Solar Neighbourhood from the White Dwarf Luminosity Function

    OpenAIRE

    Rowell, Nicholas

    2013-01-01

    The termination in the white dwarf luminosity function is a standard diagnostic tool for measuring the total age of nearby stellar populations. In this paper, an algorithm is presented for inverting the full white dwarf luminosity function to obtain a maximum likelihood estimate of the time varying star formation rate of the host stellar population. Tests with synthetic data demonstrate that the algorithm converges over a wide class of underlying star formation rate forms. T...

  20. Determination of the integrated luminosity at HERA using elastic QED Compton events

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, F.D.; Alexa, C.; Rotaru, M.; Stoicea, G.; Andreev, V.; Belousov, A.; Eliseev, A.; Fomenko, A.; Gogitidze, N.; Lebedev, A.; Malinovski, E.; Rusakov, S.; Shtarkov, L.N.; Vazdik, Y. [and others; Collaboration: The H1 Collaboration

    2012-10-15

    A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep{yields}e{gamma}p. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3 %. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process. (orig.)

  1. Determination of the Integrated Luminosity at HERA using Elastic QED Compton Events

    OpenAIRE

    F.D. Aaron; Backovic, S.; Baghdasaryan, A.; Baghdasaryan, S.; Barrelet, E; A. Belousov; Belov, P; Bizot, J. C.; Boudry, V.; Bozovic-Jelisavcic, I.; Brandt, G.; Brisson, V.(LAL, Université Paris-Sud, CNRS/IN2P3, Orsay, France); Bunyatyan, A.(Max-Planck-Institut für Kernphysik, Heidelberg, Germany); Bylinkin, A; L. Bystritskaya

    2012-01-01

    A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep \\rightarrow ep. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3%. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process.

  2. A Density Dependence for Protostellar Luminosity in Class I Sources: Collaborative Accretion

    OpenAIRE

    Elmegreen, Bruce G.; Hurst, Rachel; Koenig, Xavier

    2014-01-01

    Class I protostars in three high-mass star-forming regions are found to have correlations among the local projected density of other Class I protostars, the summed flux from these other protostars, and the protostellar luminosity in the WISE 22 micron band. Brighter Class I sources form in higher-density and higher-flux regions, while low luminosity sources form anywhere. These correlations depend slightly on the number of neighbors considered (from 2 to 20) and could includ...

  3. A luminosity monitor for the A4 parity violation experiment at MAMI

    OpenAIRE

    Hammel, T.; Achenbach, P.; Baunack, S.; Capozza, L.; Diefenbach, J.; Grimm, K.; vonHarrach, D.; Imai, Y.; Kabuss, E.; Kothe, R.; Lee, J.H.; LopesGinja, A.; Maas, F. E.; SanchezLorente, A.; Schilling, E.

    2005-01-01

    A water Cherenkov luminosity monitor system with associated electronics has been developed for the A4 parity violation experiment at MAMI. The detector system measures the luminosity of the hydrogen target hit by the MAMI electron beam and monitors the stability of the liquid hydrogen target. Both is required for the precise study of the count rate asymmetries in the scattering of longitudinally polarized electrons on unpolarized protons. Any helicity correlated fluctuation ...

  4. The Planetary Nebulae Luminosity Function and distances to Virgo, Hydra I and Coma clusters

    OpenAIRE

    Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin; Okamura, S.

    2012-01-01

    The luminosity function of planetary nebulae populations in galaxies within 10-15 Mpc distance has a cut-off at bright magnitudes and a functional form that is observed to be invariant in different galaxy morphological types. Thus it is used as a secondary distance indicator in both early and late-type galaxies. Recent deep surveys of planetary nebulae populations in brightest cluster galaxies (BCGs) seem to indicate that their luminosity functions deviate from those observe...

  5. Luminosities of carbon-rich asymptotic giant branch stars in the Milky Way

    Science.gov (United States)

    Guandalini, R.; Cristallo, S.

    2013-07-01

    Context. Stars evolving along the asymptotic giant branch can become carbon-rich in the final part of their evolution. They replenish the inter-stellar medium with nuclear processed material via strong radiative stellar winds. The determination of the luminosity function of these stars, even if far from being conclusive, is extremely important for testing the reliability of theoretical models. In particular, strong constraints on the mixing treatment and the mass-loss rate can be derived. Aims: We present an updated luminosity function of Galactic carbon stars (LFGCS) obtained from a re-analysis of available data already published in previous papers. Methods: Starting from available near- and mid-infrared photometric data, we re-determined the selection criteria. Moreover, we took advantage of updated distance estimates and period-luminosity relations and we adopted a new formulation for the computation of bolometric corrections (BCs). This led us to collect an improved sample of carbon-rich sources from which we constructed an updated luminosity function. Results: The LFGCS peaks at magnitudes around -4.9, confirming the results obtained in a previous work. Nevertheless, the luminosity function presents two symmetrical tails instead of the larger high-luminosity tail characterizing the former luminosity function. Conclusions: The derived LFCGS matches the indications from recent theoretical evolutionary asymptotic giant branch models, thus confirming the validity of the choices of mixing treatment and mass-loss history. Moreover, we compare our new luminosity function with its counterpart in the Large Magellanic Cloud finding that the two distributions are very similar for dust-enshrouded sources, as expected from stellar evolutionary models. Finally, we derive a new fitting formula aimed to better determine BCs for C-stars. Table 1 is available in electronic form at http://www.aanda.org

  6. MS, S and C Stars in the Infrared. Luminosities and Mass Loss Rates

    OpenAIRE

    Guandalini, R.

    2008-01-01

    In this note I present an outline of infrared (IR) photometric AGB properties, based on two samples of Galactic Long Period Variables (C- and S-type respectively). I show the various selection criteria used during the choice of the sources and describe the motivations of observing them at near- and mid-IR wavelengths. I discuss the problems encountered in estimating their luminosity and distance and motivate the methods I choose for this purpose. Properties of the luminosity...

  7. Status of Precision Monte Carlo Tools For Luminosity Monitoring at Meson Factories

    International Nuclear Information System (INIS)

    We review recent progress in precision calculations and the development of Monte Carlo generators for luminosity monitoring at meson factories. It is shown how the theoretical accuracy reached by presently used large angle Bhabha tools at meson factories is at the 0.1% level and, therefore, comparable with that reached about a decade ago for luminosity monitoring through small-angle Bhabha scattering at LEP. (author)

  8. Radio Sources in Low-Luminosity Active Galactic Nuclei.IV. Radio Luminosity Function, Importance of Jet Power, and Radio Properties of the Complete Palomar Sample

    CERN Document Server

    Nagar, N M; Wilson, A S; Nagar, Neil M.; Falcke, Heino

    2005-01-01

    We present the completed results of a high resolution radio imaging survey of all (~200) low-luminosity active galactic nuclei (LLAGNs) and AGNs in the Palomar Spectroscopic Sample. The high incidences of pc-scale radio nuclei, with T(brightness) >=10^7 K, and sub-parsec jets argue for accreting black holes in >=50% of all LINERs and low-luminosity Seyferts; there is no evidence against all LLAGNs being mini-AGNs. The radio luminosity function (RLF) of Palomar Sample LLAGNs and AGNs extends three orders of magnitude below, and is continuous with, that of `classical' AGNs. We find marginal evidence for a low-power turnover in the RLF; nevertheless LLAGNs are responsible for a significant fraction of present day mass accretion. Adopting the jet model of Falcke & Biermann, we show that the accretion energy output in LLAGNs is dominated by the energy in the observed jets rather than the radiated bolometric luminosity. The Palomar LLAGNs and AGNs follow the same scaling between jet power and narrow line region...

  9. Upper limits on the total cosmic-ray luminosity of individual sources

    Energy Technology Data Exchange (ETDEWEB)

    Anjos, R.C.; De Souza, V. [Instituto de Física de São Carlos, Universidade de São Paulo, São Paulo (Brazil); Supanitsky, A.D., E-mail: rita@ifsc.usp.br, E-mail: vitor@ifsc.usp.br, E-mail: supanitsky@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), CONICET-UBA, Buenos Aires (Argentina)

    2014-07-01

    In this paper, upper limits on the total luminosity of ultra-high-energy cosmic-rays (UHECR) E > 10{sup 18} eV) are determined for five individual sources. The upper limit on the integral flux of GeV--TeV gamma-rays is used to extract the upper limit on the total UHECR luminosity of individual sources. The correlation between upper limit on the integral GeV--TeV gamma-ray flux and upper limit on the UHECR luminosity is established through the cascading process that takes place during propagation of the cosmic rays in the background radiation fields, as explained in reference [1]. Twenty-eight sources measured by FERMI-LAT, VERITAS and MAGIC observatories have been studied. The measured upper limit on the GeV--TeV gamma-ray flux is restrictive enough to allow the calculation of an upper limit on the total UHECR cosmic-ray luminosity of five sources. The upper limit on the UHECR cosmic-ray luminosity of these sources is shown for several assumptions on the emission mechanism. For all studied sources an upper limit on the ultra-high-energy proton luminosity is also set.

  10. Fossil group origins V. The dependence of the luminosity function on the magnitude gap

    CERN Document Server

    Zarattini, S; Sanchez-Janssen, R; Barrena, R; Boschin, W; del Burgo, C; Castro-Rodriguez, N; Corsini, E M; D'Onghia, E; Girardi, M; Iglesias-Paramo, J; Kundert, A; Mendez-Abreu, J; Vilchez, J M

    2015-01-01

    In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system ($\\Delta m_{12}$). There are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. Fossil and non-fossil systems could have different galaxy populations that should be reflected in their luminosity functions. In this work we study, for the first time, the dependence of the luminosity function parameters on $\\Delta m_{12}$ using data obtained by the fossil group origins (FOGO) project. We constructed a hybrid luminosity function for 102 groups and clusters at $z \\le 0.25$. We stacked all the individual luminosity functions, dividing them into bins of $\\Delta m_{12}$, and studied their best-fit Schechter parameters. We additionally computed a relative luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differ...

  11. AKARI IRC 2.5-5 ?m spectroscopy of infrared galaxies over a wide luminosity range

    International Nuclear Information System (INIS)

    We present the result of a systematic infrared 2.5-5 ?m spectroscopic study of 22 nearby infrared galaxies over a wide infrared luminosity range (1010 L ? < L IR < 1013 L ?) obtained from the AKARI Infrared Camera (IRC). The unique band of the AKARI IRC spectroscopy enables us to access both the 3.3 ?m polycyclic aromatic hydrocarbon (PAH) emission feature from star-forming activity and the continuum of torus-dust emission heated by an active galactic nucleus (AGN). Applying our AGN diagnostics to the AKARI spectra, we discover 14 buried AGNs. The large fraction of buried AGNs suggests that AGN activity behind the dust is almost ubiquitous in ultra-/luminous infrared galaxies (U/LIRGs). We also find that both the fraction and energy contribution of buried AGNs increase with infrared luminosity from 1010 L ? to 1013 L ?, including normal infrared galaxies with L IR < 1011 L ?. The energy contribution from AGNs in the total infrared luminosity is only ?7% in LIRGs and ?20% in ULIRGs, suggesting that the majority of the infrared luminosity originates from starburst activity. Using the PAH emission, we investigate the luminosity relation between star formation and AGNs. We find that these infrared galaxies exhibit higher star formation rates than optically selected Seyfert galaxies with the same AGN luminosities, implying that infrared galaxies could be an early evolutionary phase of AGN.

  12. Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey

    CERN Document Server

    Smith, Anthony J; Cross, Nicholas J G

    2008-01-01

    We present luminosity and surface brightness distributions of 36,663 galaxies with K-band photometry from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimation of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best fitting Schechter function parameters for the K-band luminosity function are found to be M*-5log h=-23.17 +/- 0.04, alpha=-0.8...

  13. The dependence of protostellar luminosity on environment in the Cygnus-X star-forming complex

    Energy Technology Data Exchange (ETDEWEB)

    Kryukova, E.; Megeath, S. T. [Ritter Astrophysical Observatory, Department of Physics and Astronomy, University of Toledo, Toledo, OH (United States); Hora, J. L.; Smith, Howard A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Gutermuth, R. A. [Department of Astronomy, University of Massachusetts, Amherst, MA (United States); Bontemps, S.; Schneider, N. [University Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Kraemer, K. [Institute for Scientific Research, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467 (United States); Hennemann, M.; Motte, F., E-mail: megeath@physics.utoledo.edu [Laboratoire AIM, CEA/IRFU-CNRS/INSU-Université Paris Diderot, Service d' Astrophysique, Bât. 709, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France)

    2014-07-01

    The Cygnus-X star-forming complex is one of the most active regions of low- and high-mass star formation within 2 kpc of the Sun. Using mid-infrared photometry from the IRAC and MIPS Spitzer Cygnus-X Legacy Survey, we have identified over 1800 protostar candidates. We compare the protostellar luminosity functions of two regions within Cygnus-X: CygX-South and CygX-North. These two clouds show distinctly different morphologies suggestive of dissimilar star-forming environments. We find the luminosity functions of these two regions are statistically different. Furthermore, we compare the luminosity functions of protostars found in regions of high and low stellar density within Cygnus-X and find that the luminosity function in regions of high stellar density is biased to higher luminosities. In total, these observations provide further evidence that the luminosities of protostars depend on their natal environment. We discuss the implications this dependence has for the star formation process.

  14. Size dependence of the radio luminosity - mechanical power correlation in radio galaxies

    CERN Document Server

    Shabala, Stanislav

    2013-01-01

    We examine the relationship between source radio luminosity and kinetic power in Active Galactic Nucleus (AGN) jets. We show that neglecting various loss processes can introduce a systematic bias in the jet powers inferred from radio luminosities for a sample of radio galaxies. This bias can be corrected for by considering source size as well as radio luminosity; effectively the source size acts as a proxy for source age. Based on a sample of FR-II radio sources with jet powers derived from the measured hotspot parameters, we empirically determine a new expression for jet power that accounts for the source size, Q_jet / 10^{36} W = 1.5 (L_151 / 10^{27} W/Hz)^{0.8} (1+z)^{1.0} (D / kpc)^{0.58 \\pm 0.17}, where D is source size and L_151 the 151 MHz radio luminosity. By comparing a flux-limited and volume-limited sample, we show that any derived radio luminosity - jet power relation depends sensitively on sample properties, in particular the source size distribution and the size-luminosity correlation inherent i...

  15. Luminosity distance in ``Swiss cheese'' cosmology with randomized voids. II. Magnification probability distributions

    Science.gov (United States)

    Flanagan, Éanna É.; Kumar, Naresh; Wasserman, Ira; Vanderveld, R. Ali

    2012-01-01

    We study the fluctuations in luminosity distances due to gravitational lensing by large scale (?35Mpc) structures, specifically voids and sheets. We use a simplified “Swiss cheese” model consisting of a ?CDM Friedman-Robertson-Walker background in which a number of randomly distributed nonoverlapping spherical regions are replaced by mass-compensating comoving voids, each with a uniform density interior and a thin shell of matter on the surface. We compute the distribution of magnitude shifts using a variant of the method of Holz and Wald , which includes the effect of lensing shear. The standard deviation of this distribution is ˜0.027 magnitudes and the mean is ˜0.003 magnitudes for voids of radius 35 Mpc, sources at redshift zs=1.0, with the voids chosen so that 90% of the mass is on the shell today. The standard deviation varies from 0.005 to 0.06 magnitudes as we vary the void size, source redshift, and fraction of mass on the shells today. If the shell walls are given a finite thickness of ˜1Mpc, the standard deviation is reduced to ˜0.013 magnitudes. This standard deviation due to voids is a factor ˜3 smaller than that due to galaxy scale structures. We summarize our results in terms of a fitting formula that is accurate to ˜20%, and also build a simplified analytic model that reproduces our results to within ˜30%. Our model also allows us to explore the domain of validity of weak-lensing theory for voids. We find that for 35 Mpc voids, corrections to the dispersion due to lens-lens coupling are of order ˜4%, and corrections due to shear are ˜3%. Finally, we estimate the bias due to source-lens clustering in our model to be negligible.

  16. THE MID-INFRARED LUMINOSITIES OF NORMAL GALAXIES OVER COSMIC TIME

    International Nuclear Information System (INIS)

    Modern population synthesis models estimate that 50% of the rest-frame K-band light is produced by thermally pulsing asymptotic giant branch (TP-AGB) stars during the first Gyr of a stellar population, with a substantial fraction continuing to be produced by the TP-AGB over a Hubble time. Between 0.2 and 1.5 Gyr, intermediate-mass stars evolve into TP-AGB C stars which, due to significant amounts of circumstellar dust, emit half their energy in the mid-IR. We combine these results using published mid-IR colors of Galactic TP-AGB M and C stars to construct simple models for exploring the contribution of the TP-AGB to 24 ?m data as a function of stellar population age. We compare these empirical models with an ensemble of galaxies in the Chandra Deep Field South from z = 0 to z = 2, and with high-quality imaging in M81. Within the uncertainties, the TP-AGB appears responsible for a substantial fraction of the mid-IR luminosities of galaxies from z = 0 to z = 2, the maximum redshift to which we can test our hypothesis, while, at the same time, our models reproduce much of the detailed structure observed in mid-IR imaging of M81. The mid-IR is a good diagnostic of star formation over timescales of ?1.5 Gyr, but this implies that ongoing star formation rates at z = 1 may be overestimated by factors of ?1.5-6, depending on the nature of star formation events. Our results, if confirmed through subsequent work, have strong implications for the star formation rate density of the universe and the growth of stellar mass over time.

  17. Extra-galactic high-energy transients: event rate density and luminosity function

    Science.gov (United States)

    Sun, Hui; Zhang, Bing; Li, Zhuo

    2015-08-01

    Several types of extra-galactic high-energy transients have been discovered, which include high-luminosity and low-luminosity long-duration gamma-ray bursts (GRBs), short-duration GRBs, supernova shock breakouts (SBOs), and tidal disruption events (TDEs) without or with a relativistic jet. In this paper, we apply a unified method to systematically study the reshift-dependent event rate densities and luminosity functions of these extra-galactic high-energy transients. We consider star formation history as the tracer of the redshift distribution for long GRBs and SBOs. For short GRBs, we consider the compact star merger model to introduce several possible merger delay time distribution models. For TDEs, we consider the mass distribution of supermassive black holes as a function of redshift. We derive some empirical formulae for the redshift-dependent event rate density for different types of transients. Based on the observed events, we derive the local specific event rate density, ?0,L ? d?0/dL for each type of transient, which represents its luminosity function. All the transients are consistent with having a single power law luminosity function, except the high luminosity long GRBs (HL-lGRBs), whose luminosity function can be well described by a broken power law. The total event rate density for a particular transient depends on the luminosity threshold, and we obtain the following values in units of Gpc-3 yr-1: 2.82^{+0.41}_{-0.36} for HL-lGRBs above 4×1049 erg s-1 218^{+130}_{-86} for low luminosity long GRBs above 6×1046 erg s-1 3.18^{+0.88}_{-0.70}, 2.87^{+0.80}_{-0.64}, and 6.25^{+1.73}_{-1.38} above 5×1049 erg s-1 for short GRBs with three different merger delay models (Gaussian, log-normal, and power law); 2.0^{+2.6}_{-1.3}×104 above 9×1043 erg s-1 for SBOs, 3.0^{+1.0}_{-0.8}×105 for normal TDEs above 1042 erg s-1 and 6.2^{+8.2}_{-4.0} above 3×1047 erg s-1for TDE jets as discovered by Swift. Intriguingly, the global specific event rate densities of different kinds of transients roughly line up in a line. The global luminosity function, which covers above 12 orders of magnitude, is consistent with a single power law with an index of -1.6.

  18. An Investigation of X-ray Luminosity versus Crystalline Powder Granularity

    Energy Technology Data Exchange (ETDEWEB)

    Borade, Ramesh; Bourret-Courchesne, Edith; ,

    2012-03-07

    At the High-throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a "full-size" scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi{sub 4}Ge{sub 3}O{sub 12} (BGO), Lu{sub 2}SiO{sub 5}:Ce (LSO), YAlO{sub 3}:Ce (YAP:Ce), and CsBa{sub 2}I{sub 5}:Eu{sup 2+} (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-{micro}m crystal grain sizes for BGO and LSO, for 310- to 600-{micro}m crystal grain sizes for CBI, and for crystal grains larger than 165{micro}m for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000- {micro}m crystal grain size range down to the 20- to 36-{micro}m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Ce exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-{micro}m crystal grains to the 20- to 36-{micro}m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-{micro}m crystal grain range to the 36- to 50-{micro}m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 {micro}m.

  19. On the maximum accretion luminosity of magnetized neutron stars: connecting X-ray pulsars and ultraluminous X-ray sources

    Science.gov (United States)

    Mushtukov, Alexander A.; Suleimanov, Valery F.; Tsygankov, Sergey S.; Poutanen, Juri

    2015-12-01

    We study properties of luminous X-ray pulsars using a simplified model of the accretion column. The maximal possible luminosity is calculated as a function of the neutron star (NS) magnetic field and spin period. It is shown that the luminosity can reach values of the order of 1040 erg s-1 for the magnetar-like magnetic field (B ? 1014 G) and long spin periods (P ? 1.5 s). The relative narrowness of an area of feasible NS parameters which are able to provide higher luminosities leads to the conclusion that L ? 1040 erg s-1 is a good estimate for the limiting accretion luminosity of an NS. Because this luminosity coincides with the cut-off observed in the high-mass X-ray binaries luminosity function which otherwise does not show any features at lower luminosities, we can conclude that a substantial part of ultraluminous X-ray sources are accreting neutron stars in binary systems.

  20. Luminosity measurement in H1; Mesure de la luminosite pour l'experience H1

    Energy Technology Data Exchange (ETDEWEB)

    Frisson, T

    2006-10-15

    At HERA, luminosity is determined on-line and bunch by bunch by measuring the Bremsstrahlung spectrum from e-p collisions. The Hl collaboration has built a completely new luminosity system in order to sustain the harsh running conditions after the fourfold luminosity increase. Namely, the higher synchrotron radiation doses and the increased event pile-up have governed the design of the two major components, a radiation resistant quartz-fibre electro-magnetic calorimeter, and a fast read-out electronic with on-line energy histogram loading at a rate of 500 kHz. The group was in charge of the electronic and the on-line data analysis of the new luminosity system. In this thesis, I present analysis tools and methods to improve the precision of the luminosity measurement. The energy scale and acceptance calculation methods set out in this thesis permit these values to be determined every four minutes, to an accuracy of 0.5 parts per thousand for the energy scale and 2 parts per thousand for the acceptance. From these results, the degree of accuracy obtained on the luminosity measurement is between 6.5 and 9.5 parts per thousand. These results are currently undergoing validation, with the aim of becoming the standard H1 method. I also studied quasi-elastic Compton events to cross-check the luminosity measurement using the 2003- 2004 and 2005 data. Indeed, this process has a well calculable cross section and a clear experimental signature. The leptonic final state consists of a coplanar e-gamma system, both observable in the central H1 detector. (author)

  1. Jets and the Accretion Flow in Low Luminosity Black Holes

    CERN Document Server

    Gardner, Emma

    2012-01-01

    We present a broadband (radio - X-rays) spectral model for black hole binaries (BHBs) in the low/hard state (LHS). We model the accretion flow as a disc which is replaced in the inner regions by a radiatively inefficient hot flow. The flow emits cyclo-synchrotron radiation, which produces another source of seed photons for Compton scattering as well as those intercepted from the outer disc. We balance heating with Compton cooling to derive the electron temperature self-consistently, and find the dominant source of seed photons changes from disc to cyclo-synchrotron emission as accretion rate drops and the disc recedes. This reproduces the observed behaviour of the X-ray spectral index, which initially hardens with decreasing accretion rate, and then softens again. We include a conical synchrotron jet of constant bulk Lorentz factor with parameters based on those observed from a bright low/hard state in GX339-4. This model reproduces the observed $L_R\\propto L_X^{0.7}$ radio-X-ray correlation as expected for a...

  2. Risk Factors

    Science.gov (United States)

    ... cells do not invade nearby tissues or spread. Risk Factors Key Points Factors That are Known to Increase ... Prevention Endometrial Cancer Prevention Lung Cancer Prevention Environmental Risk Factors Being exposed to chemicals and other substances in ...

  3. The evolution of the near-infrared galaxy luminosity function and colour bimodality up to z ~= 2 from the UKIDSS Ultra Deep Survey Early Data Release

    Science.gov (United States)

    Cirasuolo, M.; McLure, R. J.; Dunlop, J. S.; Almaini, O.; Foucaud, S.; Smail, Ian; Sekiguchi, K.; Simpson, C.; Eales, S.; Dye, S.; Watson, M. G.; Page, M. J.; Hirst, P.

    2007-09-01

    We present new results on the cosmological evolution of the near-infrared (near-IR) galaxy luminosity function (LF), derived from the analysis of a new sample of ~22000KAB Ultra Deep Survey (UDS). Our study has exploited the multiwavelength coverage of the UDS field provided by the new UKIDSS WFCAM K- and J-band imaging, the Subaru/XMM-Newton Deep Survey and the Spitzer Wide-Area Infrared Extragalactic survey. The unique combination of large area and depth provided by this new survey minimizes the complicating effect of cosmic variance and has allowed us, for the first time, to trace the evolution of the brightest sources out to z ~= 2 with good statistical accuracy. In agreement with previous studies, we find that the characteristic luminosity of the near-IR LF brightens by ~=1 mag between z = 0 and z ~= 2, while the total density decreases by a factor of ~=2. Using the rest-frame (U - B) colour to split the sample into red and blue galaxies, we confirm the classic luminosity-dependent colour bimodality at z ~ 1.5. Due to the large size of our sample, we are able to investigate the differing cosmological evolution of the red and blue galaxy populations. It is found that the space density of the brightest red galaxies (MK ~ 1.

  4. The Demographics of Broad-Line Quasars in the Mass-Luminosity Plane. I. Testing FWHM-Based Virial Black Hole Masses

    CERN Document Server

    Shen, Yue

    2011-01-01

    (Abridged) We jointly constrain the LF and BHMF of quasars using a Bayesian approach that describes the underlying active BHMF and Eddington ratio distribution to match the observed distributions in the quasar mass-luminosity plane, based on ~58,000 uniformly selected quasars from the SDSS DR 7 at z~0.4-5. We take into account the selection effect of the sample flux limit; more importantly, we deal with the statistical scatter between true BH masses and FWHM-based single-epoch virial mass estimates, as well as potential luminosity-dependent biases of these mass estimates. The LF is tightly constrained in the regime sampled by SDSS quasars, and makes reasonable predictions when extrapolated to ~3 magnitudes fainter than the SDSS flux limit. On the other hand, we find it difficult to constrain the BHMF to within a factor of a few at z>~0.7. This is mainly driven by the unknown luminosity-dependent bias of these virial mass estimators and its degeneracy with other model parameters, and secondly driven by the fac...

  5. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: modeling of the luminosity and colour dependence in the Data Release 10

    CERN Document Server

    Guo, Hong; Zehavi, Idit; Xu, Haojie; Eisenstein, Daniel J; Weinberg, David H; Bahcall, Neta A; Berlind, Andreas A; Comparat, Johan; McBride, Cameron K; Ross, Ashley J; Schneider, Donald P; Skibba, Ramin A; Swanson, Molly E C; Tinker, Jeremy L; Tojeiro, Rita; Wake, David A

    2014-01-01

    We investigate the luminosity and colour dependence of clustering of CMASS galaxies in the Sloan Digital Sky Survey-III Baryon Oscillation Spectroscopic Survey Tenth Data Release. The halo occupation distribution framework is adopted to model the projected two-point correlation function measurements on small and intermediate scales (from $0.02$ to $60\\,h^{-1}{\\rm {Mpc}}$) and to interpret the observed trends and infer the connection of galaxies to dark matter halos. We find that luminous red galaxies reside in massive halos of mass $M{\\sim}10^{13}$--$10^{14}\\,h^{-1}{\\rm M_\\odot}$ and more luminous galaxies are more clustered and hosted by more massive halos. The strong small-scale clustering requires a fraction of these galaxies to be satellites in massive halos, with the fraction at the level of 5--8 per cent and decreasing with luminosity. The characteristic mass of a halo hosting on average one satellite galaxy above a luminosity threshold is about a factor $8.7$ larger than that of a halo hosting a centra...

  6. The DEEP Groth Strip Survey X Number Density and Luminosity Function of Field E\\/S0 Galaxies at z < 1

    CERN Document Server

    Im, M; Faber, S M; Koo, D C; Gebhardt, K; Willmer, C N A; Phillips, A; Illingworth, G D; Vogt, N P; Sarajedini, V L; Im, Myungshin

    2002-01-01

    We present the luminosity function and color-redshift relation of a magnitude-limited sample of 145 mostly red field E/S0 galaxies at z 1.5. Constructing a luminosity function of the full sample of 145 E/S0s, we find that there is about 1.1--1.9 magnitude brightening in rest-frame B band luminosity back to z = 0.8 from z=0, consistent with other studies. Together with the red colors, this brightening favors models in which the bulk of stars in red field E/S0s formed before z_{for} > 1.5 and have been evolving rather quiescently with few large starbursts since then. Evolution in the number density of field E/S0 galaxies is harder to measure, and uncertainties in the raw counts and their ratio to local samples might amount to as much as a factor of two. Within that uncertainty, the number density of red E/S0s to z = 0.8 seems relatively static, being comparable to or perhaps moderately less than that of local E/S0s depending on the assumed cosmology. A doubling of E/S0 number density since z = 1 can be ruled o...

  7. Luminosity Functions of Spitzer Identified Protostars in Nine Nearby Molecular Clouds

    CERN Document Server

    Kryukova, E; Gutermuth, R A; Pipher, J; Allen, T S; Allen, L E; Myers, P C; Muzerolle, J

    2012-01-01

    We identify protostars in Spitzer surveys of nine star-forming molecular clouds within 1 kpc: Serpens, Perseus, Ophiuchus, Chamaeleon, Lupus, Taurus, Orion, Cep OB3, and Mon R2, which combined host over 700 protostar candidates. Our diverse cloud sample allows us to compare protostar luminosity functions in these varied environments. We combine photometry from 2MASS J, H, and Ks bands and Spitzer IRAC and MIPS 24 micron bands to create 1 - 24 micron spectral energy distributions (SEDs). Using protostars from the c2d survey with well-determined bolometric luminosities (Lbol), we derive a relationship between Lbol, L_MIR (integrated from 1 - 24 microns), and SED slope. Estimations of Lbol for protostar candidates are combined to create luminosity functions for each cloud. Contamination due to edge-on disks, reddened Class II sources, and galaxies is estimated and removed from the luminosity functions. We find that luminosity functions for high mass star forming clouds peak near 1 Lsun and show a tail extending ...

  8. Dark-ages reionization & galaxy formation simulation IV: UV luminosity functions of high-redshift galaxies

    CERN Document Server

    Liu, Chuanwu; Angel, P W; Duffy, Alan R; Geil, Paul M; Poole, Gregory B; Mesinger, Andrei; Wyithe, J Stuart B

    2015-01-01

    In this paper we present calculations of the UV luminosity function predictions from the Dark-ages Reionization And Galaxy-formation Observables from Numerical Simulations (DRAGONS) project, which combines N-body, semi-analytic and semi-numerical modeling designed to study galaxy formation during the Epoch of Reionization. Using galaxy formation physics including supernova feedback, the model naturally reproduces the UV LFs for high-redshift star-forming galaxies from $z{\\sim}5$ through to $z{\\sim}10$. We investigate the predicted luminosity-star formation rate (SFR) relation, finding that variable SFR histories of galaxies result in a scatter around the mean relation of $0.1$-$0.3$ dex depending on UV luminosity. We find close agreement between the model and observationally derived SFR functions. We use our predicted luminosities to investigate the luminosity function below current detection limits, and the ionizing photon budget for reionization. We predict that the slope of the UV LF remains steep below cu...

  9. The luminosity bias relation from filaments in the Sloan Digital Sky Survey Data Release Four

    CERN Document Server

    Pandey, B; Pandey, Biswajit; Bharadwaj, Somnath

    2007-01-01

    We compare quantitative estimates of the filamentarity of the galaxy distribution in seven nearly two dimensional sections from the survey against the predictions of LCDM N-body simulations. The filamentarity of the actual galaxy distribution is known to be luminosity dependent. It is also known that the filamentarity of the simulated galaxy distribution is highly sensitive to the bias, and the simulations are consistent with the data for only a narrow range of bias. We apply this feature to several volume limited subsamples with different luminosities to determine a luminosity bias relation. The relative bias $b/b^*$ as a function of the luminosity ratio $L/L^*$ is found to be well described by a straight line $b/b^*=A + B (L/L^*)$ with $A=0.833 \\pm 0.009$ and $B=0.171 \\pm 0.009$. Comparing with the earlier works all of which use ratios of the two-point statistics, we find that our results are consistent with Norberg et al.(2001) and Tegmark et al.(2004), while a steeper luminosity dependence found by Benois...

  10. Luminosity Dependence and Redshift Evolution of Strong Emission-line Diagnostics in Star-Forming Galaxies

    CERN Document Server

    Cowie, Lennox L; Songaila, Antoinette

    2015-01-01

    We examine the redshift evolution of standard strong emission-line diagnostics for Hbeta-selected star-forming galaxies using the local SDSS sample and a new z = 0.2 - 2.3 sample obtained from HST WFC3 grism and Keck DEIMOS and MOSFIRE data. We use the SDSS galaxies to show that there is a systematic dependence of the strong emission-line properties on Balmer-line luminosity, which we interpret as showing that both the N/O abundance and the ionization parameter increase with increasing line luminosity. Allowing for the luminosity dependence tightens the diagnostic diagrams and the metallicity calibrations. The combined SDSS and high-redshift samples show that there is no redshift evolution in the line properties once the luminosity correction is applied, i.e., all galaxies with a given L(Hbeta) have similar strong emission-line distributions at all the observed redshifts. We argue that the best metal diagnostic for the high-redshift galaxies may be a luminosity-adjusted version of the [NII]6584/Halpha metalli...

  11. PHAT XIII: The Cepheid Period-Luminosity Relation in M31 Based on the PHAT Survey

    CERN Document Server

    Wagner-Kaiser, R; Dalcanton, J J; Williams, B F; Dolphin, A

    2015-01-01

    Using Hubble Space Telescope Advanced Camera for Surveys (HST/ACS) and Wide Field Camera 3 (WFC3) observations from the Panchromatic Hubble Andromeda Treasury (PHAT), we present new period-luminosity relations for Cepheid variables in M31. Cepheid from several ground-based studies are identified in the PHAT pho- tometry to derive new Period-Luminosity and Wesenheit Period-Luminosity relations in the NIR and visual filters. We derive a distance modulus to M31 of 24.51+/-0.08 in the IR bands and 24.32+/-0.09 in the visual bands, including the first PL relations in the F475W and F814W filters for M31. Our derived visual and IR distance moduli dis- agree at slightly more than a 1-{\\sigma} level. Differences in the Period-Luminosity relations between ground-based and HST observations are investigated for a subset of Cepheids. We find a significant discrepancy between ground-based and HST Period-Luminosity relations with the same Cepheids, suggesting adverse effects from photometric contam- ination in ground-based ...

  12. Far Infrared Luminosity Function of Local Star-forming Galaxies in the AKARI Deep Field South

    CERN Document Server

    Sedgwick, Chris; Pearson, Chris; Matsuura, Shuji; Shirahata, Mai; Oyabu, Shinki; Goto, Tomotsugu; Matsuhara, Hideo; Clements, D L; Negrello, Mattia; White, Glenn J

    2011-01-01

    We present a far-infrared galaxy luminosity function for the local universe. We have obtained 389 spectroscopic redshifts for galaxies observed at 90 microns in the AKARI Deep Field South, using the AAOmega fibre spectrograph via optical identifications in the digitized sky survey and 4m-class optical imaging. For the luminosity function presented in this paper, we have used those galaxies which have redshifts 0luminosity function has been prepared using the 1/Vmax method. We also separate the luminosity function between galaxies which show evidence of predominantly star-forming activity and predominantly active galactic nucleus (AGN) activity in their optical spectra. Our luminosity function is in good agreement with the previous 90 micron lumino...

  13. The DEEP2 Galaxy Redshift Survey: Color and Luminosity Dependence of Galaxy Clustering at z~1

    CERN Document Server

    Coil, Alison L; Croton, Darren; Cooper, Michael C; Davis, Marc; Faber, S M; Gerke, Brian F; Koo, David C; Padmanabhan, Nikhil; Wechsler, Risa H; Weiner, Benjamin J

    2007-01-01

    We present measurements of the color and luminosity dependence of galaxy clustering at z~1 in the DEEP2 Galaxy Redshift Survey. Using volume-limited subsamples in bins of both color and luminosity, we find that: 1) The clustering dependence is much stronger with color than with luminosity and is as strong with color at z~1 as is found locally. We find no dependence of the clustering amplitude on color for galaxies on the red sequence, but a significant dependence on color for galaxies within the blue cloud. 2) For galaxies in the range L/L*~0.7-2, a stronger large-scale luminosity dependence is seen for all galaxies than for red and blue galaxies separately. The small-scale clustering amplitude depends significantly on luminosity for blue galaxies, with brighter samples having a stronger rise on scales r_p<0.5 Mpc/h. 3) Redder galaxies exhibit stronger small-scale redshift-space distortions ("fingers of god"), and both red and blue populations show large-scale distortions in xi(r_p,pi) due to coherent infa...

  14. The K band galaxy luminosity functions of three massive high redshift clusters of galaxies

    CERN Document Server

    Ellis, S C

    2004-01-01

    K band observations of the galaxy populations of three high redshift (z=0.8-1.0), X-ray selected, massive clusters are presented. The observations reach a depth of K=21.5, corresponding to K*+3.5 mag. The evolution of the galaxy properties are discussed in terms of their K band luminosity functions and the K band Hubble diagram of brightest cluster galaxies. The bulk of the galaxy luminosities, as characterised by the parameter K* from the Schechter (1976) function, are found to be consistent with passive evolution with a redshift of formation of z_f~1.5-2. This is consistent with observations of other high redshift clusters, but may be in disagreement with galaxies in the field at similar redshifts. A good match to the shape of the Coma cluster luminosity function is found by simply dimming the high redshift luminosity function by an amount consistent with passive evolution. The evolution of the cumulative fraction of K band light as a function of luminosity shows no evidence of merger activity in the bright...

  15. Evolution of the X-ray Luminosity in Young HII Galaxies

    CERN Document Server

    González, D Rosa; Bailón, E Jiménez; Terlevich, R; Ranalli, P; Comastri, A; Laird, E; Nandra, K

    2009-01-01

    In an effort to understand the correlation between X-ray emission and present star formation rate (SFR), we obtained XMM-Newton data to estimate the X-ray luminosities of a sample of actively starforming HII galaxies. The obtained X-ray luminosities are compared to other well known tracers of star formation activity such as the far infrared and the ultraviolet luminosities. We also compare the obtained results with empirical laws from the literature and with recently published analysis applying synthesis models. We use the time delay between the formation of the stellar cluster and that of the first X-ray binaries, in order to put limits on the age of a given stellar burst. We conclude that the generation of soft X-rays, as well as the Ha or infrared luminosities is instantaneous. The relation between the observed radio and hard X-ray luminosities, on the other hand, points to the existence of a time delay between the formation of the stellar cluster and the explosion of the first massive stars and the conseq...

  16. Theoretical insights into the RR Lyrae K-band Period-Luminosity relation

    CERN Document Server

    Bono, G; Castellani, V; Marconi, M

    2001-01-01

    Based on updated nonlinear, convective pulsation models computed for several values of stellar mass, luminosity and metallicity, theoretical constraints on the K-band Period-Luminosity (PLK) relation of RR Lyrae stars are presented. We show that for each given metal content the predicted PLK is marginally dependent on uncertainties of the stellar mass and/or luminosity. Then, by considering the RR Lyrae masses suggested by evolutionary computations for the various metallicities, we obtain that the predicted infrared magnitude M_K over the range 0.0001< Z <0.02 is given by the relation MK=0.568-2.071logP+0.087logZ-0.778logL/Lo, with a rms scatter of 0.032 mag. Therefore, by allowing the luminosities of RR Lyrae stars to vary within the range covered by current evolutionary predictions for metal-deficient (0.0001< Z <0.006) horizontal branch models, we eventually find that the infrared Period-Luminosity- Metallicity (PLZK) relation is MK=0.139-2.071(logP+0.30)+0.167logZ, with a total intrinsic dispe...

  17. The Galaxy Cluster Mid-Infrared Luminosity Function at 1.3

    CERN Document Server

    Wylezalek, Dominika; De Breuck, Carlos; Stern, Daniel; Brodwin, Mark; Galametz, Audrey; Gonzalez, Anthony H; Jarvis, Matt; Hatch, Nina; Seymour, Nick; Stanford, Spencer A

    2014-01-01

    We present 4.5 {\\mu}m luminosity functions for galaxies identified in 178 candidate galaxy clusters at 1.3 1.3. The luminosity functions are derived for different redshift and richness bins, and the IRAC imaging reaches depths of m*+2, allowing us to measure the faint end slopes of the luminosity functions. We find that {\\alpha} = -1 describes the luminosity function very well in all redshifts bins and does not evolve significantly. This provides evidence that the rate at which the low mass galaxy population grows through star formation, gets quenched and is replenished by in-falling field galaxies does not have a major net effect on the shape of the luminosity function. Our measurements for m* are consistent with passive evolution models and high formation redshifts z_f ~ 3. We find a slight trend towards fainter m* for the richest clusters, implying that the most massive clusters in our sample could contain older stellar populations, yet another example of cosmic downsizing. Modelling shows that a contribu...

  18. An Alternative High Luminosity LHC with Flat Optics and Long-Range Beam-Beam Compensation

    CERN Document Server

    Fartoukh, Stephane; Shatilov, Dmitry

    2015-01-01

    In the baseline scenario of the High-Luminosity LHC (HL-LHC), the geometric loss of luminosity in the two high luminosity experiments due to collisions with a large crossing angle is recovered by tilting the bunches in the interaction region with the use of crab cavities. A possible backup scenario would rely on a reduced crossing angle together with flat optics (with different horizontal and vertical ?? values) for the preservation of luminosity performance. However, the reduction of crossing angle coupled with the flat optics significantly enhances the strength of long-range beam-beam interactions. This paper discusses the possibility to mitigate the long-range beam-beam effects by current bearing wire compensators (or e-lens). We develop a new HL-LHC parameter list and analyze it in terms of integrated luminosity performance as compared to the baseline. Further, we evaluate the operational scenarios using numerical simulations of single-particle dynamics with beam-beam effects.

  19. THE BIVARIATE SIZE-LUMINOSITY RELATIONS FOR LYMAN BREAK GALAXIES AT z {approx} 4-5

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Kuang-Han; Su, Jian [Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Ferguson, Henry C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Ravindranath, Swara, E-mail: kuanghan@pha.jhu.edu [The Inter-University Center for Astronomy and Astrophysics, Pune University Campus, Pune 411007, Maharashtra (India)

    2013-03-01

    We study the bivariate size-luminosity distribution of Lyman break galaxies (LBGs) selected at redshifts around 4 and 5 in GOODS and the HUDF fields. We model the size-luminosity distribution as a combination of log-normal distribution (in size) and Schechter function (in luminosity), therefore it enables a more detailed study of the selection effects. We perform extensive simulations to quantify the dropout-selection completenesses and measurement biases and uncertainties in two-dimensional size and magnitude bins, and transform the theoretical size-luminosity distribution to the expected distribution for the observed data. Using maximum-likelihood estimator, we find that the Schechter function parameters for B {sub 435}-dropouts and are consistent with the values in the literature, but the size distributions are wider than expected from the angular momentum distribution of the underlying dark matter halos. The slope of the size-luminosity (RL) relation is similar to those found for local disk galaxies, but considerably shallower than local early-type galaxies.

  20. Dependence of Fanaroff-Riley dichotomy of radio galaxies on luminosity and redshift

    CERN Document Server

    Singal, Ashok K

    2012-01-01

    We investigate the dependence of the Fanaroff-Riley (FR) I/II dichotomy of radio galaxies on their luminosities and redshifts. Because of a very strong redshift-luminosity correlation (Malmquist bias) in a flux-limited sample, any redshift-dependent effect could appear as a luminosity related effect and vice versa. A question could then arise - do all the morphological differences seen in the two classes (FR I and II types) of sources, usually attributed to the differences in their luminosities, could these all as well be a result of mainly a cosmological evolutionary effect (e.g., due to the changing ambient density) with cosmic epoch? Even a sharp break in luminosity, seen among the two classes, could after all reflect a rather critical ambient density value. A doubt on these lines does not seem to have been raised in past and things have never been examined keeping this particular aspect in mind. We want to ascertain the customary prevalent view in the literature that the systematic differences in the two ...

  1. The HerMES sub-millimetre local and low-redshift luminosity functions

    CERN Document Server

    Marchetti, L; Franceschini, A; Arumugam, V; Aussel, H; Bethermin, M; Bock, J; Boselli, A; Buat, V; Burgarella, D; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Farrah, D; Feltre, A; Glenn, J; Griffin, M; Hatziminaoglou, E; Heinis, S; Ibar, E; Ivison, R J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rigopoulou, D; Roseboom, I G; Rowan-Robinson, M; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Symeonidis, M; Valtchanov, I; Viero, M; Wang, L; Wardlow, J; Xu, C K; Zemcov, M

    2015-01-01

    We used wide area surveys over 39 deg$^2$ by the HerMES collaboration, performed with the Herschel Observatory SPIRE multi-wavelength camera, to estimate the low-redshift, $0.02luminosity functions (LFs) of galaxies at 250, 350 and 500$\\,\\mu$m. SPIRE flux densities were also combined with Spitzer photometry and multi-wavelength archival data to perform a complete SED fitting analysis of SPIRE detected sources to calculate precise k-corrections, as well as the bolometric infrared (8-1000$\\,\\mu$m) luminosity functions and their low-$z$ evolution from a combination of statistical estimators. Integration of the latter prompted us to also compute the local luminosity density (LLD) and the comoving star formation rate density (SFRD) for our sources, and to compare them with theoretical predictions of galaxy formation models. The luminosity functions show significant and rapid luminosity evolution already at low redshifts, $0.02

  2. A Level 1 Tracking Trigger for the CMS Experiment at the LHC Phase 2 Luminosity Upgrade

    CERN Document Server

    Pozzobon, Nicola

    2011-01-01

    The second decade of Large Hadron Collider operations, from about 2020 onwards, envisages a remarkable increase in collider instantaneous luminosity, one order of magnitude above the project one. This luminosity increase presents several challenges to the LHC experiments. The present tracker of the Compact Muon Solenoid experiment must be replaced with a system providing excellent tracking quality at higher luminosities, as well as Tracking Trigger inputs to the existing “Level 0” CMS trigger system at the full 40 MHz bunch-crossing rate. The minimal requirements for a Tracking Trigger would be the capability to confirm the presence of high-pT tracks associated with Calorimeter and/or Muon Level 0 triggers. The ability to provide eective isolation criteria may also be required, and would in any case substantially improve the Trigger performance. Maintaining the data rates generated by Tracking Trigger inputs within a manageable bandwidth requires sensor modules able to locally sparsify the data. Measuring...

  3. Calculating Luminosity Distance versus Redshift in FRW Cosmology via Homotopy Perturbation Method

    CERN Document Server

    Shchigolev, V K

    2015-01-01

    We propose an efficient analytical method for estimating the luminosity distance in a homogenous Friedmann-Robertson-Walker (FRW) model of the Universe. This method is based on the homotopy perturbation method (HPM), which has high accuracy in many nonlinear problems, and can be easily implemented. For analytical calculation of the luminosity distance, we offer to proceed not from the computation of the integral, which determines it, but from the solution of a certain differential equation with corresponding initial conditions. Solving this equation by means of HPM, we obtain the approximate analytical expressions for the luminosity distance as a function of redshift for two different types of homotopy. Possible extension of this method to other cosmological models is also discussed.

  4. The Star Formation and AGN luminosity relation: Predictions from a semi-analytical model

    CERN Document Server

    Gutcke, Thales A; Maccio`, Andrea V; Lacey, Cedric

    2015-01-01

    In a Universe where AGN feedback regulates star formation in massive galaxies, a strong correlation between these two quantities is expected. If the gas causing star formation is also responsible for feeding the central black hole, then a positive correlation is expected. If powerful AGNs are responsible for the star formation quenching, then a negative correlation is expected. Observations so far have mainly found a mild correlation or no correlation at all (i.e. a flat relation between star formation rate (SFR) and AGN luminosity), raising questions about the whole paradigm of "AGN feedback". In this paper, we report the predictions of the GALFORM semi-analytical model, which has a very strong coupling between AGN activity and quenching of star formation. The predicted SFR-AGN luminosity correlation appears negative in the low AGN luminosity regime, where AGN feedback acts, but becomes strongly positive in the regime of the brightest AGN. Our predictions reproduce reasonably well recent observations by Rosa...

  5. Statistics and properties of HII regions in a sample of grand design galaxies; 1, luminosity functions

    CERN Document Server

    Rozas, M; Knapen, J H

    1995-01-01

    We present new high quality continuum-subtracted H alpha images of the grand-design galaxies NGC 157, NGC 3631, NGC 6764 and NGC 6951. We have determined the positions, angular sizes, and fluxes of their individual HII regions, and describe statistical properties of the HII region samples. We construct luminosity functions for all the HII regions in the disc and separately for arm and interarm zones for each galaxy. The slopes of the luminosity functions for the complete sample agree well with values published for other spiral galaxies of comparable morphological type. For three galaxies we determined the slopes of the luminosity functions for the spiral arm and interarm zones separately. We find that for NGC 157, NGC 3631, and NGC 6951 these slopes are equal within the errors of determination. We compare our results to those found from earlier work, specifically for M51 and NGC 6814, and discuss implications for massive star forming processes.

  6. Study of luminosity and time evolution in X-ray afterglows of GRBs

    CERN Document Server

    Dainotti, Maria Giovanna; Singal, Jack; Ostrowski, Michal

    2013-01-01

    Gamma-ray bursts (GRBs), which have been observed up to redshifts $z \\approx 9.5$ can be good probes of the early universe and have the potential of testing cosmological models. The analysis by Dainotti of GRB Swift afterglow lightcurves with known redshifts and definite X-ray plateau shows an anti-correlation between the \\underline{rest frame} time when the plateau ends (the plateau end time) and the calculated luminosity at that time (or approximately an anti-correlation between plateau duration and luminosity). We present here an update of this correlation with a larger data sample of 101 GRBs with good lightcurves. Since some of this correlation could result from the redshift dependences of these intrinsic parameters, namely their cosmological evolution we use the Efron-Petrosian method to estimate the luminosity and time evolution and to correct for this effects to determine the intrinsic nature of this correlation.

  7. CO luminosity function from Herschel-selected galaxies and the contribution of AGN

    CERN Document Server

    Vallini, L; Pozzi, F; Vignali, C; Zamorani, G

    2015-01-01

    We derive the CO luminosity function (LF) for different rotational transitions (i.e. (1-0), (3-2), (5-4)) starting from the Herschel LF by Gruppioni et al. and using appropriate $L'_{\\rm CO} - L_{\\rm IR}$ conversions for different galaxy classes. Our predicted LFs fit the data so far available at $z\\approx0$ and $2$. We compare our results with those obtained by semi-analytical models (SAMs): while we find a good agreement over the whole range of luminosities at $z\\approx0$, at $z\\approx1$ and $z\\approx2$ the tension between our LFs and SAMs in the faint and bright ends increases. We finally discuss the contribution of luminous AGN ($L_{X}>10^{44}\\,\\rm{erg\\,s^{-1}}$) to the bright end of the CO LF concluding that they are too rare to reproduce the actual CO luminosity function at $z\\approx2$.

  8. Galaxy And Mass Assembly (GAMA): the wavelength dependence of galaxy structure versus redshift and luminosity

    CERN Document Server

    Kennedy, Rebecca; Baldry, Ivan; Holwerda, Boris Häußler Benne W; Hopkins, Andrew M; Kelvin, Lee S; Lange, Rebecca; Moffett, Amanda J; Popescu, Cristina C; Taylor, Edward N; Tuffs, Richard J; Vika, Marina; Vulcani, Benedetta

    2015-01-01

    We study how the sizes and radial profiles of galaxies vary with wavelength, by fitting S\\'ersic functions simultaneously to imaging in nine optical and near-infrared bands. To quantify the wavelength dependence of effective radius we use the ratio, $\\mathcal{R}$, of measurements in two restframe bands. The dependence of S\\'ersic index on wavelength, $\\mathcal{N}$, is computed correspondingly. Vulcani et al. (2014) have demonstrated that different galaxy populations present sharply contrasting behaviour in terms of $\\mathcal{R}$ and $\\mathcal{N}$. Here we study the luminosity dependence of this result. We find that at higher luminosities, early-type galaxies display a more substantial decrease in effective radius with wavelength, whereas late-types present a more pronounced increase in S\\'ersic index. The structural contrast between types thus increases with luminosity. By considering samples at different redshifts, we demonstrate that lower data quality reduces the apparent difference between the main galaxy...

  9. Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

    CERN Document Server

    Datte, P S; Haguenauer, Maurice; Manfredi, P F; Manghisoni, M; Millaud, J E; Placidi, Massimo; Ratti, L; Riot, V J; Schmickler, Hermann; Speziali, V; Traversi, G; Turner, W C; 10.1109/TNS.2003.809473

    2003-01-01

    A novel segmented multigap pressurized gas ionization chamber is being developed for optimization of the luminosity of the Large Hadron Collider (LHC). The ionization chambers are to be installed in the front quadrupole and 0 degrees neutral particle absorbers in the high luminosity interaction regions (IRs) and sample the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The ionization chambers are instrumented with low noise, fast pulse-shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. In this paper, we report the initial results of our second test of this instrumentation in a super proton synchrotron (SPS) external proton beam. Single 300 GeV protons are used to simulate the hadronic/electromagnetic showers produced by the forward collision products from the interaction regions of the LHC. The capability of instrumentation to measure the luminosity of individual bunches in a 40 MHz bunch train is demonstrated. (10 refs) .

  10. Initial test results of an ionization chamber shower detector for a LHC luminosity monitor

    International Nuclear Information System (INIS)

    A novel, segmented, multi-gap, pressurized gas ionization chamber is being developed for optimization of the luminosity of the LHC. The ionization chambers are to be installed in the front quadrupole and zero degree neutral particle absorbers in the high luminosity IRs and sample the energy deposited near the maxima of the hadronic/electromagnetic showers in these absorbers. The ionization chambers are instrumented with low noise, fast, pulse shaping electronics to be capable of resolving individual bunch crossings at 40 MHz. In this paper we report the initial results of our second test of this instrumentation in an SPS external proton beam. Single 300 GeV protons are used to simulate the hadronic/electromagnetic shower produced by the forward collision products from the interaction regions of the LHC. The capability of instrumentations to measure the luminosity of individual bunches in a 40 MHz bunch train is demonstrated

  11. The Planetary Nebulae Luminosity Function and distances to Virgo, Hydra I and Coma clusters

    CERN Document Server

    Arnaboldi, Magda; Gerhard, Ortwin; Okamura, S

    2012-01-01

    The luminosity function of planetary nebulae populations in galaxies within 10-15 Mpc distance has a cut-off at bright magnitudes and a functional form that is observed to be invariant in different galaxy morphological types. Thus it is used as a secondary distance indicator in both early and late-type galaxies. Recent deep surveys of planetary nebulae populations in brightest cluster galaxies (BCGs) seem to indicate that their luminosity functions deviate from those observed in the nearby galaxies. We discuss the evidence for such deviations in Virgo, and indicate which physical mechanisms may alter the evolution of a planetary nebula envelope and its central star in the halo of BCGs. We then discuss preliminary results for distances for the Virgo, Hydra I and Coma clusters based on the observed planetary nebulae luminosity functions.

  12. The planetary nebulae luminosity function and distances to the Virgo, Hydra i, and Coma Clusters

    Science.gov (United States)

    Arnaboldi, Magda; Longobardi, Alessia; Gerhard, Ortwin; Okamura, S.

    2013-02-01

    The luminosity function of planetary nebula populations in galaxies at distances within 10-15 Mpc exhibits a cut-off at bright magnitudes and a functional form that is observed to be invariant among different galactic morphological types. Therefore, it is used as a secondary distance indicator applicable to both early- and late-type galaxies. Recent deep surveys of planetary nebula populations in brightest cluster galaxies (BCGs) seem to indicate that their luminosity functions deviate from those observed in the nearby galaxies. We discuss the evidence for such deviations in the Virgo Cluster, and indicate which physical mechanisms may alter the evolution of a planetary nebula envelope and its central star in the halo of BCGs. We then discuss preliminary results for distances to the Virgo, Hydra i, and Coma Clusters based on the observed planetary nebulae luminosity functions.

  13. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: -> Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. -> Deconvolution of the luminosity spectrum distortion due to the ISR emission. -> Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  14. Correction of beam-beam effects in luminosity measurement in the forward region at CLIC

    CERN Document Server

    Lukic, Strahinja

    2013-01-01

    Procedures for correcting the beam-beam effects in luminosity measurement at CLIC at 3 TeV CM energy are described and tested using Monte Carlo simulations: - Correction of the angular counting loss due to the combined Beamstrahlung and initial-state radiation (ISR) effects, based on the reconstructed velocity of the collision frame of the Bhabha scattering. - Deconvolution of the luminosity spectrum distortion due to the ISR emission. - Correction of the counting bias due to the finite calorimeter energy resolution. All procedures were tested by simulation. Bhabha events were generated using BHLUMI, and used in Guinea-PIG to simulate the outgoing momenta of Bhabha particles in the bunch collisions at CLIC. Residual uncertainties after correction are listed in a table in the conclusions. The beam-beam related systematic counting uncertainty in the luminosity peak can be reduced to the order of permille.

  15. THE RADIO LUMINOSITY FUNCTION AND GALAXY EVOLUTION IN THE COMA CLUSTER

    International Nuclear Information System (INIS)

    We investigate the radio luminosity function and radio source population for two fields within the Coma cluster of galaxies, with the fields centered on the cluster core and southwest infall region and each covering about half a square degree. Using VLA data with a typical rms sensitivity of 28 ?Jy per 4.''4 beam, we identify 249 radio sources with optical counterparts brighter than r = 22. For cluster galaxies, these correspond to L 1.4 = 1.7 x 1020 W Hz-1(for a 5? source) and Mr = -13. Comprehensive optical spectroscopy identifies 38 of these as members of the Coma cluster, evenly split between sources powered by an active nucleus and sources powered by active star formation. The radio-detected star-forming galaxies are the dominant population only at radio luminosities between about 1021 and 1022 W Hz-1, an interesting result given star formation dominates field radio luminosity functions for all luminosities lower than about 1023 W Hz-1. The majority of the radio-detected star-forming galaxies have characteristics of starbursts, including high specific star formation rates and optical spectra with strong emission lines. In conjunction with prior studies on post-starburst galaxies within the Coma cluster, this is consistent with a picture in which late-type galaxies entering Coma undergo a starburst prior to a rapid cessation of star formation. Optically bright elliptical galaxies (Mr ? -20.5) make the largest contribution to the radio luminosity function at both the high (?>3x1022 W Hz-1) and low (?21 W Hz-1) ends. Through a stacking analysis of these optically bright ellipticals we find that they continue to harbor radio sources down to luminosities as faint as 3 x 1019 W Hz-1. However, contrary to published results for the Virgo cluster we find no evidence for the existence of a population of optically faint (Mr ? -14) dwarf ellipticals hosting strong radio AGNs.

  16. Low-redshift formula for the luminosity distance in a LTB model with cosmological constant

    International Nuclear Information System (INIS)

    We calculate the low-redshift Taylor expansion for the luminosity distance for an observer at the center of a spherically symmetric matter inhomogeneity with a non-vanishing cosmological constant. We then test the accuracy of the formulas comparing them to the numerical calculation for different cases for both the luminosity distance and the radial coordinate. The formulas can be used as a starting point to understand the general non-linear effects of a local inhomogeneity in the presence of a cosmological constant, without making any special assumption as regards the inhomogeneity profile. (orig.)

  17. X-ray luminosity functions of different morphological and X-ray type AGN populations

    OpenAIRE

    Povi?, M.; García, A. M. Pérez; Sánchez-Portal, M.; Bongiovanni, A.; Cepa, J; Lorenzo, M. Fernández; Lara-López, M. A.; Gallego, J.; Ederoclite, A; Márquez, I; Masegosa, J; Alfaro, E.; Castañeda, H; González-Serrano, J. I.; González, J J

    2013-01-01

    Luminosity functions are one of the most important observational clues when studying galaxy evolution over cosmic time. In this paper we present the X-ray luminosity functions of X-ray detected AGN in the SXDS and GWS fields. The limiting fluxes of our samples are 9.0x10^(-15) and 4.8x10^(-16) erg/cm^2/sec^(-1) in the 0.5 - 7.0 keV band in the two fields, respectively. We carried out analysis in three X-ray bands and in two redshift intervals up to z < 1.4. Moreover, we deri...

  18. The K band galaxy luminosity functions of three massive high redshift clusters of galaxies

    OpenAIRE

    Ellis, S. C .; Jones, L. R.

    2003-01-01

    K band observations of the galaxy populations of three high redshift (z=0.8-1.0), X-ray selected, massive clusters are presented. The observations reach a depth of K=21.5, corresponding to K*+3.5 mag. The evolution of the galaxy properties are discussed in terms of their K band luminosity functions and the K band Hubble diagram of brightest cluster galaxies. The bulk of the galaxy luminosities, as characterised by the parameter K* from the Schechter (1976) function, are fo...

  19. The X-ray Luminosity Function of Bright Clusters in the Local Universe

    OpenAIRE

    De Grandi, S.; Guzzo, L.; Böhringer, H.; Molendi, S.; Chincarini, G.; Collins, C.; Cruddace, R.; Neumann, D; S.; Schindler; Schuecker, P.; VOGES, W

    1998-01-01

    We present the X-ray luminosity function (XLF) for clusters of galaxies derived from the RASS1 Bright Sample. The sample, selected from the ROSAT All-Sky Survey in a region of 2.5 sr within the southern Galactic cap, contains 130 clusters with flux limits in the range ~ 3-4 x 10^-12 ergs/cm^2/s in the 0.5-2.0 keV band. A maximum-likelihood fit with a Schechter function of the XLF over the entire range of luminosities (0.045 - 28. x 10^44 ergs/s), gives alpha = 1.52 +/- 0.11,...

  20. Searches for resonances in the tb and tc final states at the high-luminosity LHC

    OpenAIRE

    Drueke, Elizabeth; Schoenrock, Brad; Gonzalez, Barbara Alvarez; Schwienhorst, Reinhard

    2013-01-01

    We study resonances decaying to one top quark and one additional quark (b or c) at the low- luminosity and high-luminosity 14 TeV LHC and at a future 33 TeV hadron collider in the context of Snowmass 2013. A heavy W boson that preferentially couples to quarks can be found through its decay to tb. A Kaluza-Klein gluon might have a significant branching ratio to tc. The final state in these searches has a lepton and neutrino from a W boson decay plus two jets, at least one of ...