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1

A UNIFORM CORRELATION BETWEEN SYNCHROTRON LUMINOSITY AND DOPPLER FACTOR IN GAMMA-RAY BURSTS AND BLAZARS: A HINT OF SIMILAR INTRINSIC LUMINOSITIES?  

International Nuclear Information System (INIS)

We compile 23 gamma-ray bursts (GRBs) and 21 blazars with estimated Doppler factors, and the Doppler factors of GRBs are estimated from their Lorentz factors by assuming their jet viewing angles ? ? 00. Using the conventional assumption that the prompt emission of GRBs is dominated by the synchrotron radiation, we calculate the synchrotron luminosity of GRBs from their total isotropic energy and burst duration. Intriguingly, we discover a uniform correlation between the synchrotron luminosity and Doppler factor, Lsyn?D3.1, for GRBs and blazars, which suggests that they may share some similar jet physics. One possible reason is that GRBs and blazars have, more or less, similar intrinsic synchrotron luminosities and both of them are strongly enhanced by the beaming effect. After Doppler and redshift correction, we find that the intrinsic peak energy of the GRBs ranges from 0.1 to 3 keV with a typical value of 1 keV. We further correct the beaming effect for the observed luminosity of GRBs and find that a positive correlation exists between the intrinsic synchrotron luminosity and peak energy for GRBs, which is similar to that of blazars. Our results suggest that both the intrinsic positive correlation and the beaming effect may be responsible for the observed tight correlation between the isotropic energy and the peak energy in GRBs (the so-called Amati relation).

2

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

CERN Document Server

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 ...

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

3

Luminosity and Redshift Dependence of the Covering Factor of Active Galactic Nuclei viewed with WISE and Sloan Digital Sky Survey  

Science.gov (United States)

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 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.

Toba, Y.; Oyabu, S.; Matsuhara, H.; Malkan, M. A.; Gandhi, P.; Nakagawa, T.; Isobe, N.; Shirahata, M.; Oi, N.; Ohyama, Y.; Takita, S.; Yamauchi, C.; Yano, K.

2014-06-01

4

Ruling factors in the impact of collision debris on the LHC high luminosity insertion magnets  

International Nuclear Information System (INIS)

The Large Hadron Collider (LHC) built at CERN now enters a starting-up phase in order to reach the present design luminosity (L0) of 1034 cm-2·s-1. A possible upgrade of the machine to a luminosity value of 10 L0 requires a new design of some insertion region magnets, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion region magnetic elements and in particular in the superconducting magnet coils with a possible risk of quench. The role of the key parameters (such as the magnet aperture, the crossing plane, the thickness of a possible shielding liner, ...) is pointed out, in order to optimize the design of the new insertion regions for the Upgrade phase I aiming to reach 2-3 L0. (author)

5

Luminosity calculation  

International Nuclear Information System (INIS)

The luminosity of the Tevatron collider was calculated. The data used for the calculation are the flying wire transverse beam profile and the SBD bunch profile. For the 900 GeV/c mini beta runs, the calculation was compared to the CDF luminosity monitor. The ratio of the calculation and C:BOLUMP is 0.95. 1 ref., 9 figs., 4 tabs

6

The CO luminosity and CO-H2 conversion factor of diffuse ISM: does CO emission trace dense molecular gas?  

CERN Document Server

Aims: We wish to separate and quantify the CO luminosity and CO-H2 conversion factor applicable to diffuse but partially-molecular ISM when H2 and CO are present but C+ is the dominant form of gas-phase carbon. Methods: We discuss galactic lines of sight observed in \\HI, HCO+ and CO where CO emission is present but the intervening clouds are diffuse (locally \\AV\\ $\\la 1$ mag) with relatively small CO column densities $\\NCO \\la 2\\times10^{16}\\pcc$. We separate the atomic and molecular fractions statistically using \\EBV\\ as a gauge of the total gas column density and compare NH2 to the observed CO brightness. Results: Although there are H2-bearing regions where CO emission is too faint to be detected, the mean ratio of integrated CO brightness to NH2 for diffuse ISM does not differ from the usual value of 1\\K km/s of integrated CO brightness per $2\\times10^{20}$ H2 $\\pcc$ . Moreover, the luminosity of diffuse CO viewed perpendicular to the galactic plane is 2/3 that seen at the Solar galactic radius in surveys ...

Liszt, Harvey; Lucas, Robert

2010-01-01

7

Luminosity optimization  

CERN Document Server

Once circulating beams have been established residual transverse offsets remain at the interaction points which can be the source of a significant luminosity reduction. Using the Van der Meer scan method, where one beam is swept stepwise across the other while measuring the collision rate as a function of beam displacement, these offsets can be minimized in order to optimize the luminosity. This method was successfully used during the 2009 LHC run at the four interaction points. The first experience, measurements and problems encountered will be presented as well as possible improvements for the upcoming run.

White, S M

2010-01-01

8

Notes on luminosity variation at ISABELLE  

International Nuclear Information System (INIS)

In the present ISABELLE design, the luminosity at each insertion will be the same, unless special efforts are taken to get a low-? insertion or reduced crossing angle. These can only change the luminosity by factors of 2 to 4 from insertion to insertion. An estimation of the range of desired luminosities is given

9

OLYMPUS luminosity monitoring  

Energy Technology Data Exchange (ETDEWEB)

The OLYMPUS experiment at DESY has been measuring the ratio of positron-proton and electron-proton elastic scattering cross sections 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 and polarization transfer methods. In order to control the systematic uncertainties to the percent level, the luminosities are monitored redundantly 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. During two data taking periods, performances of GEM and MWPC luminosity monitors are presented.

Ates, Ozgur [Hampton University, Hampton, Virginia (United States); Collaboration: OLYMPUS-Collaboration

2013-07-01

10

Dijet spectroscopy at high luminosity  

International Nuclear Information System (INIS)

A study of the dijet mass resolution has been made appropriate to high luminosity operation. As a benchmark, the mass resolution of W ? jj for a Higgs boson of 800 GeV has been optimized for no, eight, and sixteen overlapping minbias events. A factor of 2.5 degradation in Mjj width is seen. 6 refs., 10 figs

11

Luminosity Function of GRBs  

CERN Document Server

We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count--flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal distribution, (b) Schechter distribution, and (c) Scale-free distribution. We assume several models of the evolution of the GRB population for each luminosity function. Our analysis shows that: (a) log-normal is the only luminosity function that is compatible with both the observations. This result is independent of the GRB evolution model, (b) for log-normal function, the average photon luminosity $L_0$ and the width of the luminosity function $\\sigma$ that are compatible with both the observations fall in the range: $10^{55} sec^{-1} \\la L_0 \\la 10^{56} sec^{-1}$ and $2 \\la \\sigma \\la 3$, (c) the agreement of observations with other luminosity functions requires the GRB population to evolve more strongly than the evolution of the star-formation rate of the universe.

Sethi, S; Sethi, Shiv

2001-01-01

12

Luminosity Optimization in DAFNE  

CERN Document Server

DAFNE the Frascati F-factory, started the two beams commissioning on March 1998. Since then a relevant amount of experience concerning the techniques and procedures for optimizing the luminosity has been acquired. All the schemes used are strongly based on the use of various diagnostic systems including a dedicated luminosity monitor, orbit measurement, tune monitor, synchrotron light monitor and others. A summary of the used techniques, with accent on the diagnostic aspects, is presented.

Sannibale, F

2000-01-01

13

SDC at high luminosity  

International Nuclear Information System (INIS)

Why is it prudent to plan for a luminosity (L) of >1034/(cm2sec) from the beginning? First, the SSC is easily capable of attaining high luminosity. In comparison, for bar pp machines such as the Tevatron, increases in L are difficult. Second, after early runs at design luminosity, the only simple upgrade to a general purpose detector is an increase in luminosity. Third, and most important, the only known model independent physics goal of SSC is in the electroweak sector; the ZZ scattering amplitude reaches the unitarity bound for ?s ? 3 TeV. In order to reach this mass range, and assure that some new physics is found, high luminosity running is needed. Since high luminosity running is desirable and easily attainable, it is inevitable. Therefore, one should build the ''hooks'' for upgrades to high L into the SDC from the beginning. The experience of CDF is that if this is not done, upgrades can be painful. Specifically, if possible, SDC should make sure that the chosen technologies allow high L operation. The time to plan for the whole useful lifetime of SDC is from the beginning. 9 refs., 6 figs

14

A Luminosity Calorimeter for CLIC  

CERN Document Server

For the relative precision of the luminosity measurement at CLIC, a preliminary target value of 1% is being assumed. This may be accomplished by constructing a finely granulated calorimeter, which will measure Bhabha scattering at small angles. In order to achieve the design goal, the geometrical parameters of the calorimeter need to be defined. Several factors influence the design of the calorimeter; chief among these is the need to minimize the error on the luminosity measurement while avoiding the intense beam background at small angles. In this study the geometrical parameters are optimized for the best performance of the calorimeter. In addition, the suppression of physics background to Bhabha scattering is investigated and a set of selection cuts is introduced.

Abramowicz, H; Kananov, S; Levy, A; Sadeh, I

2009-01-01

15

Estimating galaxy luminosity functions.  

Science.gov (United States)

In this work a comparison between different galaxy luminosity function estimators by means of Monte-Carlo simulations is presented. The simulations show that the C(-) method of Lynden-Bell (1971) and the STY method derived by Sandage, Tammann & Yahil (1979) are the best estimators to measure the shape of the luminosity function. The simulations also show that the STY estimator has a bias such that the faint-end slope is underestimated for steeper inclinations of the Schechter Function, and that this bias becomes quite severe when the sample contains only a few hundred objects. Overall, the C(-) is the most robust estimator, being less affected by different values of the faint end slope of the Schechter parameterization and sample size. The simulations are also used to compare different estimators of the luminosity function normalization. They demonstrate that most methods bias the recovered mean density towards values which are ~ 20% lower than the input value.

Willmer, C. N. A.

1997-09-01

16

Luminosities of AGB Variables  

CERN Document Server

The prevailing evidence suggests that most large-amplitude AGB variables follow the period luminosity (PL) relation that has been established for Miras in the LMC and galactic globular clusters. Hipparcos observations indicate that most Miras in the solar neighbourhood are consistent with such a relation. There are two groups of stars with luminosities that are apparently greater than the PL relation would predict: (1) in the LMC and SMC there are large amplitude variables, with long periods, P> 420 days, which are probably undergoing hot bottom burning, but which are very clearly more luminous than the PL relation (these are visually bright and are likely to be among the first stars discovered in more distant intermediate age populations); (2) in the solar neighbourhood there are short period, P<235 days, red stars which are probably more luminous than the PL relation. Similar short-period red stars, with high luminosities, have not been identified in the Magellanic Clouds.

Whitelock, P A

2002-01-01

17

Luminosity measurement at CMS  

CERN Document Server

The measurement of the luminosity delivered by the LHC is pivotal for several key physics analyses. During the first three years of running, tremendous steps forwards have been made in the comprehension of the subtleties related to luminosity monitoring and calibration, which led to an unprecedented accuracy at a hadron collider. The detectors and corresponding algorithms employed to estimate online and offline the luminosity in CMS are described. Details are given concerning the procedure based on the Van der Meer scan technique that allowed a very precise calibration of the luminometers from the determination of the LHC beams parameters. What is being prepared in terms of detector and online software upgrades for the next LHC run is also summarized.

Leonard, Jessica Lynn

2014-01-01

18

Luminosity enhancements at SLAC  

International Nuclear Information System (INIS)

Several ideas are discussed that have been proposed to improve the luminosity at the SPEAR and PEP electron-positron storage rings and to insure good luminosity at the SLAC Linear Collider. There have been two proposals studied recently for SPEAR: a Microbeta insertion using Samarium Cobalt permanent magnets, and a Minibeta insertion using conventional quadrupole magnets. The notations Microbeta and minibeta used here are somewhat arbitrary since the front faces of the first quadrupole magnets for both insertions are at nearly the same distance from the interaction point

19

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.

20

Results From the DAFNE High Luminosity Test  

Energy Technology Data Exchange (ETDEWEB)

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 {center_dot} 10{sup 32} cm{sup -2}s{sup -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 10{sup 36} cm{sup -2} s{sup -1} and it has been also taken into account to upgrade one of the LHC interaction regions.

Milardi, C.; Alesini, D.; Biagini, M.E.; Boni, R.; Boscolo, M.; Bossi, F.; Buonomo, B.; Clozza, A.; Delle Monache, G.; Demma, T.; Di Pasquale, E.; Di Pirro, G.; Drago, A.; Gallo, A.; Ghigo, A.; Guiducci, S.; Ligi, C.; Marcellini, F.; Mazzitelli, G.; Murtas, F.; Pellegrino, L.; /Frascati /Novosibirsk, IYF /CERN /INFN, Cosenza /INFN, Rome /KEK, Tsukuba /Orsay, LAL /Rome U. /Pisa U. /INFN, Pisa /INFN, Rome3 /SLAC

2012-04-11

 
 
 
 
21

Luminosity upgrades on PEP  

International Nuclear Information System (INIS)

Over the past two years the authors have explored several ideas for Luminosity Upgrades on PEP. This followed the recommendation of the Goldhaber Committee which concluded that unless PETRA uncovered new physics at higher energies then PEP should concentrate on higher luminosity at its present energy. These studies explored many schemes which involved lowering the ? functions (stronger focussing) at the interaction points, as it has been employed at CESR, PETRA, DORIS II and in PEP. The first round of studies assumed that all six interaction regions would be required and that the overall chromatic aberrations which could be tolerated and corrected should not exceed their present value. This led to designs which incorporated quadrupoles for the low-? insertions which were placed inside the magnetic field region of the detectors. Because of the high fields in some of the detectors, these quadrupoles would have to be either superconducting iron-free, or permanent magnet (samarium-cobalt) designs. Although machine lattice designs were readily achievable using these techniques, the engineering complexity and the impact on detectors made these schemes rather unattractive. This forced a review of the above assumptions and led to the studies of the Mini-Maxi Beta and the Six-Fold Mini Beta schemes described in this paper. 2 figures, 1 table

22

Supernova type I luminosity  

International Nuclear Information System (INIS)

The full time-dependent radiation spectrum of a supernova starts when the explosion shock wave reaches the surface of the presupernova envelope. An early radiation spectrum emitted by the expanded and cooling shock-ejected outer layers of an initially compact (R = 108 cm) type I supernova is derived. The relativistically ejected matter is presumably cosmic rays. The Doppler shifted and relativistically time contracted Planck radiation emitted from the expanding surface layers results in an emitted radiation associated with the cooling corresponding to an energy flux of 1.3 x 1043 t-1.05 ergs sec-1 with a spectrum I(h?) dh? = 1.5 x 1043 (h?)-0.92 ergs eV-1 and time behavior (h?)/sub eff/ = 108 t-0.61 eV. The optical luminosity from the shock is thus low congruent to 1040 ergs sec-1 and 1043 ergs total so that it would not be seen as a precursor to the main optical outburst occurring several days later. The x-ray luminosity (several x 1043 ergs in milliseconds) is observable but small compared to extended envelope models. The later optical light curve is then interpreted in terms of radioactive heating, ionization and excitation by 0.2 M/sub solar/ of 56Ni decaying via 56Co to 56Fe. Van Hise (1974) has already pointed out that the two optical decay constants are closely given by the respective radioactive decay constants multiplied by 3/4. This is interpreted as requiring efficiency to produce optical radiation, the Fe+blend, proportional to the (decay rate)/sup 1/3/. It is further noted that when the two optical decay rates are extrapolated to zero time, the intercepts agree with the predicted ratio of deposited energy from 56Ni ? 56Co, and from 56Co ? 56Fe when the appropriate fractional absorption of gamma rays and beta particles is included. The width and magnitude of the peak luminosity has already been calculated by Colgate and McKee

23

Luminosity measurement in H1  

Energy Technology Data Exchange (ETDEWEB)

The HERA luminosity was determined by measuring the flux of bremsstrahlung photons emitted at zero degree off electrons in the field of protons in the interaction region. After the HERA upgrade, the H1 Collaboration developed a new luminosity system which measured all the emitted photons in a bunch crossing. We describe the expression of this photon flux in the luminosity detector which is used in the simulation of the detector. The total energy method, based on the measurement of the bremsstrahlung photon energy flux in the calorimeter, is the standard method for the off-line luminosity measurement. In this study, we propose a new method to calculate the luminosity. This new method is based on the shape of the bremsstrahlung photon energy spectrum measured in the luminosity detector. The two methods are compared. A good agreement is observed.

Frisson, T., E-mail: frisson@creatis.insa-lyon.f [Laboratoire Leprince-Ringuet - Ecole polytechnique, CNRS/IN2P3 Palaiseau F-91128 (France); Boudry, V.; Specka, A.; Moreau, F. [Laboratoire Leprince-Ringuet - Ecole polytechnique, CNRS/IN2P3 Palaiseau F-91128 (France)

2011-06-01

24

Luminosity of type I supernovae  

International Nuclear Information System (INIS)

We have recalculated the luminosity of type I supernovae by using (1) the diffusive release of Ni56 decay energy (Colgate and McKee), (2) the progressive gamma-ray transparency as calculated by a Monte Carlo gamma-ray simulation code, and (3) the fractional deposition of positrons (ARnett). If we take 100% optical fluorescence efficiency (Meyerott) and choose a nebula that is expanding uniformly and at constant velocity such that it is one ?-ray mean free path (35.5 g cm-2) thick at 20 days, we obtain excellent agreement with observations. Three independent physical phenomena are involved. The first is the diffusive release of thermal radiation that with the 6.1 day Ni56 decay determines the height and width of the optical peak. The second is the initial fast decay of the optical peak by a factor of roughly 100 as determined by the progressive transparency to ?-rays. The third is the apparent 56 day half-life that results from the progressive escape of the positron fraction of the 77 day Co56 decay. To obtain agreement with observations, each of these three independent phenomena requires that the expanding nebula be described by a single relation M/sub ej/ upsilon9-2=0.22 +- 0.05, where M/sub ej/ is the ejected mass in solar masses and upsilon9 is the expansion velocity in units of 109 cm s-1. Total energy requirements exclude the possibility of the ejection of an envelope > or approx. =0.75 M/sub sun/, yet the optical luminosity requires that approx.0.25 M/sub sun/ of the ejected matter be Ni56

25

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)

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.

Renata Maria Coelho Crepaldi

2010-04-01

26

High luminosity muon collider design  

Energy Technology Data Exchange (ETDEWEB)

Muon Colliders have unique technical and physics advantages and disadvantages when compared with both hadron and electron machines. They should be regarded as complementary. Parameters are given of 4 TeV high luminosity {mu}{sup +}{mu}{sup {minus}} collider, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders.

Palmer, R.; Gallardo, J.

1996-10-01

27

Luminosity Effects in Projected Fractals  

CERN Document Server

We analyze examples of projected two dimensional fractals for the case where the objects studied have a Schechter luminosity function. Our results indicate that two dimensional catalogues of sources could be of value in detecting the effects of luminosity functions as well as of large scale structure.

Thieberger, R

2002-01-01

28

Estimating White Dwarf Luminosity Functions  

Science.gov (United States)

The white dwarf luminosity function is an important tool in the study of the solar neighborhood, since it allows the determination of the age of the galactic disk. Over the years, several methods have been proposed to calculate 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, the 1/Vmax method is usually employed in computing the white dwarf luminosity function and little attention has been given to other methods --- in sharp contrast with the situation when galaxy luminosity functions are derived from a variety of samples. We present a comparison between different estimators for computing the white dwarf luminosity function.

García-Berro, E.; Geijo, E. M.; Torres, S.; Isern, J.

2005-07-01

29

Luminosity tuning at KEKB-2  

International Nuclear Information System (INIS)

We routinely make tuning on machine parameters related to beam collision at KEKB even during the physics experiment. The purpose of this adjustment called 'knob tuning' is to maintain the high luminosity by optimizing the collision parameters and to obtain an even higher luminosity. We installed crab cavities in February 2007. The method of luminosity tuning changed to some extent and some new tuning method were introduced. In this report, we describe the developments after the 2nd annual meeting of particle accelerator society of Japan 2005. (author)

30

RHIC PLANS TOWARDS HIGHER LUMINOSITY  

Energy Technology Data Exchange (ETDEWEB)

The Relativistic Heavy Ion Collider (RHIC) is designed to provide luminosity over a wide range of beam energies and species, including heavy ions, polarized protons, and tric beam collisions. In the first seven years of operation there has been a rapid increase in the achieved peak and average luminosity, substantially exceeding design values. Work is presently underway to achieve the Enhanced Design parameters. Planned major upgrades include the Electron Beam Ion Source (EBIS), RHIC-11, and construction of an electron-ion collider (eRHIC). We review the expected RHIC upgrade performance. Electron cooling and its impact on the luminosity both for heavy ions and protons are discussed in detail.

FEDOTOV,A.

2007-06-25

31

LHC luminosity upgrade detector challenges  

CERN Document Server

LHC luminosity upgrade: detector challenges 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 developments (lectures 2-4) • Electronics, trigger and data acquisition challenges (lecture 5) Note: the much more ambitious LHC energy upgrade will not be covered

CERN. Geneva; Bortoletto, Daniela; Wigmans, Richard; Riegler, Werner; Smith, Wesley H

2006-01-01

32

New method for high luminosity  

Energy Technology Data Exchange (ETDEWEB)

We propose a new method to increase a luminosity in colliding machines, where collective focusing of high-current anti-charged streams are employed as final focusing lenses instead of usual high-gradient magnets. It is shown that a counter streaming pair of a cylindrical positron and hollow electron beams produces necessary focusing forces to lead to a high luminosity, avoiding significant beam-beam effects of themselves. (orig.).

Takayama, K.; Ando, A.

1985-11-01

33

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%

34

EVOLUTION OF THE H? LUMINOSITY FUNCTION  

International Nuclear Information System (INIS)

The Smithsonian Hectospec Lensing Survey (SHELS) is a window on the star formation history over the last 4 Gyr. SHELS is a spectroscopically complete survey for Rtot 0. We use the 10k spectra to select a sample of pure star-forming galaxies based on their H? emission line. We use the spectroscopy to determine extinction corrections for individual galaxies and to remove active galaxies in order to reduce systematic uncertainties. We use the large volume of SHELS with the depth of a narrowband survey for H? galaxies at z ? 0.24 to make a combined determination of the H? luminosity function at z ? 0.24. The large area covered by SHELS yields a survey volume big enough to determine the bright end of the H? luminosity function from redshift 0.100 to 0.377 for an assumed fixed faint-end slope ? = -1.20. The bright end evolves: the characteristic luminosity L* increases by 0.84 dex over this redshift range. Similarly, the star formation density increases by 0.11 dex. The fraction of galaxies with a close neighbor increases by a factor of 2-5 for LH? ?> L* in each of the redshift bins. We conclude that triggered star formation is an important influence for star-forming galaxies with H? emission.

35

Beyond the galaxy luminosity function  

CERN Document Server

With the advent of large scale surveys (i.e., Legacy Surveys) it is now possible to start looking beyond the galaxy luminosity function (LF) to more detailed statistical representations of the galaxy population, i.e., multivariate distributions. In this review I first summarise the current state-of-play of the B-band global and cluster LFs and then briefly present two promising bivariate distributions: the luminosity-surface brightness plane (LSP); and the colour-luminosity plane (CLP). In both planes galaxy bulges and galaxy disks form marginally overlapping but distinct distributions, indicating two key formation/evolutionary processes (presumably merger and accretion). Forward progress in this subject now requires the routine application of reliable bulge-disk decomposition codes to allow independent investigation of these two key components.

Driver, S P

2004-01-01

36

Simple models for the integrated luminosity  

CERN Document Server

In this note simple analytic expressions are derived to model the integrated luminosity of the LHC for the case of exponential luminosity decays as well as for leveled luminosity evolutions. The expressions depend on few parameters that can easily be explored to evaluate the impact in the integrated luminosity. The model is compared to the LHC performance in 2012 and is used to predict integrated luminosity for HL-LHC.

Wenninger, J

2013-01-01

37

Precision luminosity measurements at LHCb  

CERN Document Server

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...

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

38

The [O II] lambda 3727 Luminosity Function at z ~ 1  

CERN Document Server

We measure the evolution of the [O II] lambda 3727 luminosity function at 0.75 < z < 1.45 using high-resolution spectroscopy of ~ 14,000 galaxies observed by the DEEP2 galaxy redshift survey. We find that brighter than L([O II])=10^{42} erg s^{-1} the luminosity function is well-represented by a power law dN/dL \\propto L^{\\alpha} with slope \\alpha ~ -3. The number density of [O II]-emitting galaxies above this luminosity declines by a factor of \\gtrsim 2.5 between z ~ 1.35 and z ~ 0.84. In the limit of no density evolution, the characteristic [O II] luminosity, defined as the luminosity where the space density equals 10^{-3.5} dex^{-1} Mpc^{-3}, declines by a factor of ~ 1.7 over the same redshift interval. These results imply a ~ 25% per Gyr decrease in the amount of star formation in galaxies during this epoch. Integrating the observed [O II] luminosity function assuming a faint-end power-law slope of -1.3 +/- 0.2, we derive the integrated star formation rate density in four redshift bins centered aro...

Zhu, Guangtun; Blanton, Michael R

2008-01-01

39

Intermediate-Luminosity Red Transients  

Science.gov (United States)

Intermediate-luminosity red transients (ILRTs) are a recently recognized class of stellar eruptions with maximum luminosities between those of classical novae and supernovae. During their outbursts, which generally last a few months, they typically evolve to extremely red colors, completely unlike novae. Prototypes include the M31 "Red Variable" of 1988, V838 Mon, SN 2008S, V1309 Sco, the M99 optical transient of 2010, and the 2008 and 2010 ILRTs in the nearby spiral NGC 300. I will present recent developments in the study of ILRTs. At present, it appears that there are (at least) two separate evolutionary channels leading to ILRT outbursts: mergers of close binaries (accounting for ILRTs in old populations and possibly V838 Mon), and eruptions on stars of about 8-12 Msun, possibly due to electron-capture SNe (accounting for ILRTs in young populations).

Bond, Howard E.; Humphreys, R. M.; Bedin, L. R.; Bonanos, A.; Davidson, K.; Monard, B.; Prieto, J.; Walter, F.

2012-01-01

40

Xray luminosity functions of LMXBs  

Science.gov (United States)

The formation and evolution of LMXBs is not well understood. The properties of a population of LMXBs depend on a number of uncertain aspects of binary evolution and therefore population studies offers a relatively new way of probing binary interactions. We have studied the shape of the faint end of the X-ray luminosity function (LF) of LMXBs in nearby galaxies with Chandra and in the Milky Way using the RXTE and the Swift all-sky monitors. We have used the binary population synthesis code SeBa to model the formation and evolution of LMXBs in the different observed environments, to understand which aspects of the evolution that is responsible for the observed luminosity functions.

Voss, Rasmus

2012-09-01

 
 
 
 
41

Galaxy Luminosity Function in Groups  

CERN Document Server

We compute the luminosity function of galaxies in groups. The data consists in two samples of groups of galaxies selected in distance and redshift space comprising a total number of 66 groups. The assignment of galaxies to the groups were derived from the Edinburgh-Durham Southern Galaxy Catalog, considering a limiting apparent magnitude $m_{lim}=19.4$. We find a flat faint end of the mean galaxy luminosity function in groups in contrast to the mean galaxy LF in clusters where a large relative number of faint galaxies is present. We find that a Schechter function with parameters $M^{*}\\simeq -19.6\\pm 0.2,$ $\\alpha \\simeq -1.0\\pm $ 0.2 provides a satisfactory fit to the galaxy LF of our total sample of groups in the range of absolute magnitudes $-22

Muriel, H; Lambas, D G; Muriel, Hernán; Valotto, Carlos A.; Lambas, Diego G.

1998-01-01

42

Luminosity Limitations at Hadron Colliders  

CERN Document Server

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.

Zimmermann, Frank

2001-01-01

43

Sprite Luminosity and Radio Noise  

Science.gov (United States)

Sprites are composed of individual streamer discharges (e.g., Pasko, 2010) which split into streamer tips (McHarg et al., 2010) with diameters 50-100 m at 60-80 km height (Kanmae et al., 2012). The sprite luminosity coincides in time and space with extremely low frequency electromagnetic radiation Cummer and Fullekrug, 2001). This theory is based on current flowing in the body of sprites at 70-80 km height associated with large streamer densities (Pasko et al., 1998). A more detailed study shows specifically that the exponential growth and splitting of streamers at 70-80 km height results in an electron multiplication associated with the acceleration of electrons to a few eV. The accelerated electrons radiate a small amount of electromagnetic energy and the incoherent superposition of many streamers causes the observed electromagnetic radiation (Qin et al., 2012). It has been predicted that this newly recognized physical mechanism might also result in low frequency ( 30-300 kHz) electromagnetic radiation emanating from sprite streamers near 40 km height in the stratosphere, albeit with very small magnetic fields 10^{-17}-10^{-12} T from a single streamer (Qin et al., 2012). The presence of this predicted radiation was promptly confirmed by low frequency radio noise measurements during dancing sprites with a very sensitive radio receiver (Fullekrug et al., 2013). Specifically, it was found that the sprite luminosity coincides with sudden enhancements of the radio noise. These initial observations are extended here with a more detailed analysis to study the spatial coherence of the radio noise recorded with a novel network of sensitive radio receivers deployed during field work in the summer 2013. This network of radio receivers is used to study the relationship between the radio noise and the sprite luminosity observed with video cameras. The sprite luminosity is inferred from video recordings by use of sophisticated image processing techniques which are applied for the first time to video footage of sprites.

Fullekrug, M.; Evans, A.; Mezentsev, A.; van der Velde, O.; Soula, S.

2013-12-01

44

Luminosities of recycled radio pulsars in globular clusters  

Science.gov (United States)

Using Monte Carlo simulations, we model the luminosity distribution of recycled pulsars in globular clusters as the brighter, observable part of an intrinsic distribution. We find that the observed luminosities can be reproduced using either lognormal or power-law distributions as the underlying luminosity function. For both distributions, a wide range of model parameters provide an acceptable match to the observed sample, with the lognormal function providing statistically better agreement in general than the power-law models. Moreover, the power-law models predict a parent population size that is a factor of between 2 and 10 times higher than for the lognormal models. We note that the lognormal luminosity distribution found for the normal pulsar population by Faucher-Giguère and Kaspi is consistent with the observed luminosities of globular cluster pulsars. For Terzan 5, our simulations show that the sample of detectable radio pulsars, and the diffuse radio flux measurement, can be explained using the lognormal luminosity law with a parent population of ˜150 pulsars. Measurements of diffuse gamma-ray fluxes for several clusters can be explained by both power-law and lognormal models, with the lognormal distributions again providing a better match in general. In contrast to previous studies, we do not find any strong evidence for a correlation between the number of pulsars inferred in globular clusters and globular cluster parameters, including metallicity and stellar encounter rate.

Bagchi, Manjari; Lorimer, D. R.; Chennamangalam, Jayanth

2011-11-01

45

Detectors and luminosity for hadron colliders  

International Nuclear Information System (INIS)

Three types of very high energy hadron-hadron colliders are discussed in terms of the trade-off between energy and luminosity. The useable luminosity depends both on the physics under study and the rate capabilities of the detector

46

Sub-L* Galaxies at Redshifts z~4, 3, and 2: Their UV Luminosity Function and Luminosity Density  

CERN Document Server

We use very deep (R_lim=27) UGRI imaging to study the evolution of the faint end of the UV-selected galaxy luminosity function from z~4 to z~2. We find that the luminosity function evolves with time and that this evolution is differential with luminosity: the number of sub-L* galaxies increases from z~4 to z~3 by at least a factor of 2.3, while the bright end of the LF remains unchanged. Potential systematic biases restrict our ability to draw strong conclusions at lower redshifts, z~2, but we can say that the number density of sub-L* galaxies at z~2.2 is at least as high as it is at z~3. Turning to the UV luminosity density of the Universe, we find that the luminosity density starts dropping with increasing redshift already beginning at z=3 (earlier than recently thought - Steidel et al. 1999) and that this drop is dominated by the same sub-L* galaxies that dominate the evolution of the LF. This differential evolution of the luminosity function suggests that differentially comparing key diagnostics of dust, ...

Sawicki, M; Sawicki, Marcin; Thompson, David

2005-01-01

47

Periods, amplitudes, and luminosities of red supergiants  

International Nuclear Information System (INIS)

The periods of 22 red supergiants have been determined using the results of electrophotometric observations. The period-luminosity-spectrum and amplitude-luminosity-spectrum dependences for the red supergiants have been obtained. The masses and luminosities of these stars are estimated

48

Precision luminosity measurement at ILC  

CERN Document Server

In these proceedings a novel approach to deal with the beam-induced effects in luminosity measurement is presented. Based on the relativistic kinematics of the collision frame of the Bhabha process, the beam-beam related uncertainties can be reduced to the permille level independently of a precision with which the beam parameters are known. Specific event selection combined with the corrective methods we introduce, leads to the systematic uncertainty from the beam-induced effects to be at a few permille level in the peak region above the 80% of the nominal centre-of-mass energies at ILC.

Bozovic-Jelisavcic, I; Pandurovic, M; Smiljanic, I

2014-01-01

49

Luminosity Measurement in the ZEUS Experiment  

International Nuclear Information System (INIS)

A precision luminosity measurement in the ZEUS experiment at the HERA electron-proton collider is described, based on the data collected by the ZEUS luminosity monitor in 1996. The method of the measurement relies on the detection of high-energy photons from the ep Bremsstrahlung process. The large cross section of this process allows for the continuous and fast monitoring of the HERA luminosity as well as for the control of the electron beam steering and focusing. A 1 % precision of the luminosity determination has been achieved. The luminosity monitor has been also extensively used for studying quasi-real photoproduction, and radiative processes in deep inelastic scattering. (author)

50

Luminosity Dependence and Search Doppler  

Science.gov (United States)

The research supported by this grant covered two projects: (1) a study of the luminosity dependence of the properties of atoll sources; and (2) a search for Doppler shifts in the pulse arrival times of the anomalous pulsar 4U 0142+61. Following the discovery of kilohertz quasi-periodic oscillations (QPOS) in Sco X-1 studies of the X-ray properties of atoll sources have been dominated by searches for these QPOS, and the study of their dependence on other source properties, such as X-ray luminosity and spectral state. In the project supported by grant NAG5-3269 we have detected kHz QPOs for several atoll sources. The physical interpretation of these QPO is as yet unclear, but simple models (such as the Keplerian beat frequency model) can probably be excluded. The results of this research have been reported. We have studied the X-ray pulsations of the anomalous X-ray pulsar 4U 0142+61 using the Rossi XTE. A detailed search for Doppler shifts did not lead to a positive detection. The upper limits exclude almost all types of possible companion stars, except white dwarfs. However, the latter can be excluded since anomalous X-ray pulsars are very young objects. We therefore conclude that anomalous X-ray pulsars are single neutron stars.

VanParadijs, Johannes A.

1998-01-01

51

The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy  

Science.gov (United States)

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 luminosity function by as much as a factor of ~2 on the bright end. This has implications for models of quasars and their role in the universe, such as quasars' contribution to cosmological backgrounds.

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

2014-05-01

52

Luminosities of recycled radio pulsars in globular clusters  

CERN Document Server

Using Monte Carlo simulations, we model the luminosity distribution of recycled pulsars in globular clusters as the brighter, observable part of an intrinsic distribution and find that the observed luminosities can be reproduced using either log-normal or power-law distributions as the underlying luminosity function. For both distributions, a wide range of model parameters provide an acceptable match to the observed sample, with the log-normal function providing statistically better agreement in general than the power-law models. Moreover, the power-law models predict a parent population size that is a factor of between two and ten times higher than for the log-normal models. We note that the log-normal luminosity distribution found for the normal pulsar population by Faucher-Gigu\\`ere and Kaspi is consistent with the observed luminosities of globular cluster pulsars. For Terzan~5, our simulations show that the sample of detectable radio pulsars, and the diffuse radio flux measurement, can be explained using ...

Bagchi, Manjari; Chennamangalam, Jayanth

2011-01-01

53

Luminosity monitoring and calibration of BLM  

International Nuclear Information System (INIS)

The BEPC 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 BES 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 ( x 1026 cm-2·count-1). With the calibration constant, the counting rates of the BLM can be scaled up to absolute luminosities. (authors)

54

The LHCb Online Luminosity Monitoring and Control  

CERN Document Server

The LHCb experiment searches for New Physics by precision measurements in heavy flavour physics. The optimization of the data taking conditions relies on accurate monitoring of the instantaneous luminosity, and many physics measurements rely on accurate knowledge of the integrated luminosity. Most of the measurements have potential systematic effects associated with pileup and changing running conditions. To cope with these while aiming at maximising the collected luminosity, a control of the LHCb luminosity was put in operation. It consists of an automatic real-time feedback system controlled from the LHCb online system which communicates directly with an LHC application which in turn adjusts the beam overlap at the interaction point. It was proposed and tested in July 2010 and has been in routine operation during 2011-2012. As a result, LHCb has been operating at well over four times the design pileup, and 95% of the integrated luminosity has been recorded within 3% of the desired luminosity.

Jacobsson, R; Follin, F

2014-01-01

55

Characterizing Luminosity Evolution in the Tevatron  

CERN Document Server

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.

McCrory, Elliott

2005-01-01

56

The Online Luminosity Calculator of ATLAS  

International Nuclear Information System (INIS)

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.

57

The luminosity function of cluster pulsars  

CERN Document Server

We study luminosities of millisecond pulsars in globular clusters by fitting the observed luminosity distribution with single and double power laws. We use simulations to model the observed distribution as the brighter part of some parent distribution for Terzan 5 and try to find a model which simultaneously agrees with the observed diffuse radio flux, total predicted number of pulsars and observed luminosity distribution. We find that wide ranges of parameters for log-normal and power-law distributions give such good models. No clear difference between the luminosity distributions of millisecond pulsars in globular clusters and normal disk pulsars was seen.

Bagchi, Manjari

2010-01-01

58

Luminosity of young Jupiters revisited. Massive cores make hot planets  

CERN Document Server

The intrinsic luminosity of young Jupiters is of high interest for planet formation theory. It is an observable quantity that is determined by important physical mechanisms during formation, namely the accretion shock structure, and even more fundamentally, the basic formation mechanism (core accretion or gravitational instability). We study the impact of the core mass on the post-formation entropy and luminosity of young giant planets forming via core accretion with a supercritical shock (cold accretion). For this, we conduct self-consistently coupled formation and evolution calculations of giant planets with masses between 1 and 12 Jovian masses and core masses between 20 and 120 Earth masses. We find that the post-formation luminosity of massive giant planets is very sensitive to the core mass. An increase of the core mass by a factor 6 results in an increase of the post-formation luminosity of a 10 Jovian mass planet by a factor 120. Due to this dependency, there is no single well defined post-formation l...

Mordasini, Christoph

2013-01-01

59

Level-1 track triggers for the ATLAS high luminosity upgrade  

CERN Document Server

The HL-LHC, the planned high luminosity upgrade for the LHC, will increase the collision rate in the ATLAS detector approximately a factor of 5 beyond the luminosity for which the detectors were designed, while also increasing the number of pile-up collisions in each event by a similar factor. This means that the level-1 trigger must achieve a higher rejection factor in a more difficult environment. This talk will discuss the challenges that arise in this environment and strategies being considered by ATLAS to include information from the tracking systems in the level-1 decision. The main challenges involve reducing the data volume exported from the tracking system for which two options are under consideration: a region of interest based system and a intelligent sensor method which filters on hits likely to come from higher transverse momentum tracks.

Lipeles, E; The ATLAS collaboration

2011-01-01

60

Missing mass from low-luminosity stars  

International Nuclear Information System (INIS)

Results from a deep photometric survey for low-luminosity stars show a turnup to the luminosity function at faint magnitudes, and reopen the possibility that the missing mass in the solar neighbourhood is made up of stars after all. (author)

 
 
 
 
61

Luminosity Monitoring in ATLAS with MPX Detectors  

CERN Document Server

The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed by CERN for the detection of multiple types of radiation. Sixteen such detectors were successfully operated in the ATLAS detector at the LHC and collected data independently of the ATLAS data-recording chain from 2008 to 2013. Each ATLAS-MPX detector provides separate measurements of the bunch-integrated LHC luminosity. An internal consistency for luminosity monitoring of about 2% was demonstrated. In addition, the MPX devices close to the beam are sensitive enough to provide relative-luminosity measurements during van der Meer calibration scans, in a low-luminosity regime that lies below the sensitivity of the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary results from these luminosity studies are presented for 2012 data taken at sqrt(s)=8 TeV proton-proton collisions.

Sopczak, Andre

2014-01-01

62

Luminosity Monitoring in ATLAS with MPX Detectors  

CERN Document Server

The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed by CERN for the detection of multiple types of radiation. Sixteen such detectors were successfully operated in the ATLAS detector at the LHC and collected data independently of the ATLAS data-recording chain from 2008 to 2013. Each ATLAS-MPX detector provides separate measurements of the bunch-integrated LHC luminosity. An internal consistency for luminosity monitoring of about 2% was demonstrated. In addition, the MPX devices close to the beam are sensitive enough to provide relative-luminosity measurements during van der Meer calibration scans, in a low-luminosity regime that lies below the sensitivity of the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary results from these luminosity studies are presented for 2012 data taken at $\\sqrt{s}=8$ TeV proton-proton collisions.

Sopczak, A; The ATLAS collaboration

2013-01-01

63

The QSO variability-luminosity-redshift relation  

CERN Document Server

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, our parametric fits show that the QSO variability-wavelength relation is consistent with that observed in low-luminosity nearby active galactic nuclei. The results are used to constrain Poissonian-type models. We find that if QSO variability results from a random superposition of pulses, then the individual events must have B-band energies between $\\sim 10^{50}$ and a few times $10^{51}$ erg and time-scales of $\\sim 2$ yr. Generalized Poissonian models in which the pulse energy and lifetime scale with luminosity are also discussed.

Fernandes, R C; Terlevich, R J

1996-01-01

64

Luminosity Monitoring in ATLAS with MPX Detectors  

Science.gov (United States)

The ATLAS-MPX detectors are based on the Medipix2 silicon devices designed by CERN for the detection of multiple types of radiation. Sixteen such detectors were successfully operated in the ATLAS detector at the LHC and collected data independently of the ATLAS data-recording chain from 2008 to 2013. Each ATLAS-MPX detector provides separate measurements of the bunch-integrated LHC luminosity. An internal consistency for luminosity monitoring of about 2% was demonstrated. In addition, the MPX devices close to the beam are sensitive enough to provide relative-luminosity measurements during van der Meer calibration scans, in a low-luminosity regime that lies below the sensitivity of the ATLAS calorimeter-based bunch-integrating luminometers. Preliminary results from these luminosity studies are presented for 2012 data taken at ? s = 8 TeV proton-proton collisions.

Asbah, Nedaa

2014-06-01

65

Reduced Wolf-Rayet line luminosities at low metallicity  

Science.gov (United States)

New NTT/EMMI spectrophotometry of single WN2-5 stars in the Small and Large Magellanic Clouds are presented, from which He ii ?4686 line luminosities have been derived, and compared with observations of other Magellanic Cloud Wolf-Rayet stars. SMC WN3-4 stars possess line luminosities which are a factor of 4 times lower than LMC counterparts, incorporating several binary SMC WN3-4 stars from the literature. Similar results are found for WN5-6 stars, despite reduced statistics, incorporating observations of single LMC WN5-9 stars from the literature. C iv ?5808 line luminosities of carbon sequence WR stars in the SMC and IC 1613 (both WO subtypes) from the recent literature are a factor of 3 lower than LMC WC stars from Mt Stromlo/DBS spectrophotometry, although similar results are also obtained for the sole LMC WO star. We demonstrate how reduced line luminosities at low metallicity follow naturally if WR winds are metallicity-dependent, as recent empirical and theoretical results suggest. We apply mass loss-metallicity scalings to atmospheric non-LTE models of Milky Way and LMC WR stars to predict the wind signatures of WR stars in the metal-poor star forming WR galaxy I Zw 18. WN He ii ?4686 line luminosities are 7-20 times lower than in metal-rich counterparts of identical bolometric luminosity, whilst WC C iv ?5808 line luminosities are 3-6 times lower. Significant He+ Lyman continuum fluxes are predicted for metal-poor early-type WR stars. Consequently, our results suggest a larger population of WR stars in I Zw 18 than is presently assumed, particularly for WN stars, potentially posing a severe challenge to evolutionary models at very low metallicity. Finally, reduced wind strengths from WR stars at low metallicities impacts upon the immediate circumstellar environment of long duration GRB afterglows, particularly since the host galaxies of high-redshift GRBs tend to be metal-poor.

Crowther, P. A.; Hadfield, L. J.

2006-04-01

66

z~1 Lya Emitters I. The Luminosity Function  

CERN Document Server

We construct a flux-limited sample of 135 candidate z~1 Lya emitters (LAEs) from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search method. These LAEs have luminosities comparable to those at high redshifts and lie within a 7 Gyr gap present in existing LAE samples. We use archival and newly obtained optical spectra to verify the UV redshifts of these LAEs. We use the combination of the GALEX UV spectra, optical spectra, and X-ray imaging data to estimate the active galactic nucleus (AGN) fraction and its dependence on Lya luminosity. We remove the AGNs and compute the luminosity function (LF) from 60 z~1 LAE galaxies. We find that the best fit LF implies a luminosity density increase by a factor of ~1.5 from z~0.3 to z~1 and ~20 from z~1 to z~2. We find a z~1 volumetric Lya escape fraction of 0.7+/-0.4%.

Wold, Isak G B; Cowie, Lennox L

2014-01-01

67

ISR Superconducting High-Luminosity (low beta ) insertion  

CERN Multimedia

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.

1981-01-01

68

Where are the z=4 Lyman Break Galaxies? Results from Conditional Luminosity Function Models of Luminosity-dependent Correlation Functions  

CERN Document Server

Using the conditional luminosity function (CLF) -- the luminosity distribution of galaxies in a dark matter halo -- as a way to model galaxy statistics, we study how z=4 Lyman Break Galaxies (LBGs) are distributed in dark matter halos. For this purpose, we measure luminosity-dependent clustering of LBGs in the Subaru/XMM-Newton Deep Field by separating a sample of 16,920 galaxies to three magnitude bins in i'-band between 24.5 and 27.5. Our models fits to data show a possible trend for more luminous galaxies to appear as satellites in more massive halos. The satellite fraction of galaxies at z=4 in these magnitude bins is 0.13 to 0.3, 0.09 to 0.22, and 0.03 to 0.14, respectively, where the 1 sigma ranges account for differences coming from two different estimates of the z=4 LF from the literature. To jointly explain the LF and the large-scale linear bias factor of z=4 LBGs as a function of rest-UV luminosity requires central galaxies to be brighter in UV at z =4 than present-day galaxies in same dark matter m...

Cooray, A R; Cooray, Asantha; Ouchi, Masami

2006-01-01

69

Luminosity measurement with the CLEO II detector  

International Nuclear Information System (INIS)

A measurement of absolute integrated luminosity is presented using the CLEO II detector operating at the CESR e+e- storage ring. Independent analyses of three different final states (e+e-, ??, and ?+?-) at ?(s) similar eq10 GeV normalize to the expected theoretical cross sections and correct for detection efficiencies. The resulting luminosities are measured with systematic errors of ±1.8%, ±1.6%, and ±2.2%, respectively, and are consistent with one another. The combined luminosity has a systematic error of ±1.0%. ((orig.))

70

Luminosities of Radio-Loud Active Galaxies  

Science.gov (United States)

We investigate the host galaxy luminosities of three different samples of radio loud active nuclei at z RLQ = -24.3, BLL= -23.7, FRI= -24.1, FRII= -23.6. Host of RLQ are ˜ 0.5 mag brighter than those of BLLs which are intermediate between RG of FR I and FR II type. These galaxy luminosities are used to evaluate the central black hole masses from the MBH -Lbulge relation found for nearby spheroidal galaxies. Finally we construct the Host Galaxy Luminosity Function for the different classes of AGN and compare its shape with that of elliptical galaxies.

Treves, Aldo; Carangelo, Nicoletta; Falomo, Renato

71

Luminosity determination at HERA-B  

International Nuclear Information System (INIS)

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 ?-rays generated in the target and comment on the possible use of such delta rays to measure luminosity. (orig.)

72

Luminosity determination at HERA-B  

Energy Technology Data Exchange (ETDEWEB)

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.)

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

73

THE z = 5 QUASAR LUMINOSITY FUNCTION FROM SDSS STRIPE 82  

Energy Technology Data Exchange (ETDEWEB)

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.

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

74

Single Bremsstrahlung luminosity measurements at DAPHINE  

Energy Technology Data Exchange (ETDEWEB)

At DAPHINE luminosity measurements are performed by detecting the photons from single Bremsstrahlung at the two interaction points. Set up and measurement method are presented with special emphasis on background subtraction schemes, error evaluation and machine related issues.

Mazzitelli, G.; Sannibale, F. E-mail: fsannibale@lbl.govfernando.sannibale@lnf.inf.it; Cervelli, F.; Lomtadze, T.; Serio, M.; Vignola, G

2002-07-01

75

Single Bremsstrahlung luminosity measurements at DAPHINE  

International Nuclear Information System (INIS)

At DAPHINE luminosity measurements are performed by detecting the photons from single Bremsstrahlung at the two interaction points. Set up and measurement method are presented with special emphasis on background subtraction schemes, error evaluation and machine related issues

76

Luminosity and spectral evolution of QSOs  

CERN Document Server

We apply the observed spectral states of the Galactic black hole candidates (GBHCs) to the quasi-stellar object (QSO) luminosity evolution based on the correlation between luminosity and the spectrum, which is strongly supported by the similarities of emission mechanisms in GBHCs and QSOs. We derive the QSO luminosity evolution trends in the UV/optical and the X-ray energy bands and demonstrate that their trends are significantly affected by the spectral evolution. Each energy band shows distinct evolution properties. We test one of the widely discussed cosmological evolution scenarios of QSOs, in which QSOs evolve as a single long-lived population, and show that the resulting luminosity functions seen in different energy bands exhibit distinguishable and potentially observable evolution signatures in the X-ray energy bands.

Choi, Y Y; Yi, I S

1999-01-01

77

Simulations of luminosity monitor for PANDA experiment  

International Nuclear Information System (INIS)

The Panda experiment at the future GSI facility FAIR (Facility of Antiprotons Research) is designed to address broad physics programs in hadron physics using the antiproton beam. The physics program includes, among other things, the study of charmonium spectrum and open charm states with high precision and search of exotic hybrids and glueballs in the charmonium mass region. While in some measurements, such as, the resonance scans to determine the resonance widths and mass, only a relative measurement of luminosity may be sufficient, the measurement of the time integrated luminosity at the interaction point is essential in most of the cases to determine the cross section for physical processes. A luminosity monitor based on Si-strip detectors is planned for the PANDA experiment. In the present work, initial simulation studies that have been started at NPD, BARC on the design and optimization of the Si-strip based luminosity monitor for the PANDA experiment have been reported

78

LHC beam and luminosity lifetimes revisited  

CERN Document Server

The single beam lifetimes and luminosity lifetime during LHC Stable Beams in 2012 for a large number of fills are considered. The evolution of single beam lifetime through a given fill is obtained from fits to BCT data and from the combination of luminosity losses and calibrated beam loss to collimation. A breakdown of the single beam lifetime into principle components is performed allowing a quantitative picture of component lifetime evolution during Stable Beams. The situation before and after the octupole polarity change and concomitant increase in chromaticity in August 2012 are compared. The analysis is extended to the luminosity lifetime and an attempt to made to evaluate emittance growth from the luminous region size and luminosity evolution through the fill.

Lamont, M

2014-01-01

79

Online Luminosity Optimization at the LHC  

CERN Document Server

The online luminosity control of the LHC experiments consists of an automatic slow real-time feedback system controlled by a specific experiment software that communicates directly with an LHC application.

Follin, F; Jacobsson, R

2014-01-01

80

The D0 Run IIb Luminosity Measurement  

CERN Document Server

An assessment of the recorded integrated luminosity is presented for data collected with the D0 detector at the Fermilab Tevatron Collider from June 2006 to September 2011 (Run IIb). In addition, a measurement of the effective cross section for inelastic interactions, also referred to as the luminosity constant, is reported. This measurement incorporates new features that lead to a substantial improvement in the precision of the result. A luminosity constant of \\sigma_{LM} = 48.3\\pm1.9\\pm0.6 mb is obtained, where the first uncertainty is due to the accuracy of the inelastic cross section used by both CDF and D0, and the second uncertainty is due to D0 sources. The recorded luminosity for the highest E_T jet trigger is L_rec = 9.2 \\pm 0.4 fb^{-1}, with a relative uncertainty of 4.3%.

Casey, B C K; DeVaughan, K; Enari, Y; Gallas, E; Katsanos, I; Linnemann, J; Orduna, J; Partridge, R; Prewitt, M; Schellman, H; Snow, G R; Verzocchi, M

2014-01-01

 
 
 
 
81

The luminosity constraint on solar neutrino fluxes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A specific linear combination of the total solar neutrino fluxes must equal the measured solar photon luminosity if nuclear fusion reactions among light elements are responsible for solar energy generation. This luminosity constraint, previously used in a limited form in testing the no neutrino oscillation hypothesis, is derived in a generality that includes all of the relevant solar neutrino fluxes and which is suitable for analyzing the results of many different solar neut...

Bahcall, John N.

2001-01-01

82

A new Method for high luminosity  

Energy Technology Data Exchange (ETDEWEB)

We propose a new method to increase a luminosity in colliding machines, where collective focussings of high current anti-charged streams are employed as final focussing lenses instead of usual high gradient magnets. It is shown that a counter streaming pair of cylindrical positron and hollow electron beams produces necessary focussing forces to lead to a high luminosity, avoiding significant beam-beam effects of themselves. A tentative scheme to produce the kiloampare positron beams is briefly proposed.

Takayama, K.; Ando, A.

1985-10-01

83

A new Method for high luminosity  

International Nuclear Information System (INIS)

We propose a new method to increase a luminosity in colliding machines, where collective focussings of high current anti-charged streams are employed as final focussing lenses instead of usual high gradient magnets. It is shown that a counter streaming pair of cylindrical positron and hollow electron beams produces necessary focussing forces to lead to a high luminosity, avoiding significant beam-beam effects of themselves. A tentative scheme to produce the kiloampare positron beams is briefly proposed

84

A new method for high luminosity  

International Nuclear Information System (INIS)

It is proposed a new method to increase a luminosity in colliding machines, where collective focusing of high-current anti-charged streams are employed as final focusing lenses instead of usual high-gradient magnets. It is shown that a counter streaming pair of a cylindrical positron and hollow electron beams produces necessary focusing forces to lead to a high luminosity, avoiding significant beam-beam effects of themselves

85

Luminosity Measurement at PEP-N  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The PEP-N experiment requires a fast on-line luminosity monitor of modest accuracy plus an off-line method of determining integrated luminosity with accuracy of 0.01 for each pb$^{-1}$. We propose the PEP-2 monitor, based on observing single bremsstrahlung at zero degrees to the positron direction at collision for the former and the use of Bhabha scatters at polar angles $>$.03 radians for the latter requirement.

Mandelkern, Mark

2001-01-01

86

Luminosity measurements with the ATLAS detector  

International Nuclear Information System (INIS)

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 detector in the years 2010 and 2011. The calibration was performed via so called van-der Meer (vdM-) scans. These scans allow to measure the convolved beam sizes in vertical and horizontal directions, which can be used, together with the precise knowledge of the beam intensities, to determine a luminosity calibration constant. Detailed evaluation of all possible error sources affecting this method including cross-checks amongst many different sub-detectors lead to a final ATLAS luminosity uncertainty for pp collisions at ?(s)=7 TeV of ?L/L=3.4% for 2010, and of ?L/L=2.2% for 2011.

87

Luminosity Optimization Feedback in the SLC  

International Nuclear Information System (INIS)

The luminosity optimization at the SLC has been limited by the precision with which one can measure the micron size beams at the Interaction Point. Ten independent tuning parameters must be adjusted. An automated application has been used to scan each parameter over a significant range and set the minimum beam size as measured with a beam-beam deflection scan. Measurement errors limited the accuracy of this procedure and degraded the resulting luminosity. A new luminosity optimization feedback system has been developed using novel dithering techniques to maximize the luminosity with respect to the 10 parameters, which are adjusted one at a time. Control devices are perturbed around nominal setpoints, while the averaged readout of a digitized luminosity monitor measurement is accumulated for each setting. Results are averaged over many pulses to achieve high precision and then fitted to determine the optimal setting. The dithering itself causes a small loss in luminosity, but the improved optimization is expected to significantly enhance the performance of the SLC. Commissioning results are reported

88

A new luminosity function for galaxies as given by the mass-luminosity relationship  

CERN Document Server

The search for a luminosity function for galaxies both alternative or companion to a Schechter function is a key problem in the reduction of data from catalogs of galaxies. Two luminosity functions for galaxies can be built starting from two distributions of mass as given by the fragmentation. A first overall distribution function is the Kiang function that represents a useful description of the area and volume distribution of the Poisson Voronoi diagrams. The second distribution, that covers the case of low mass galaxies, is the truncated Pareto distribution : in this model we have a natural bound due to the minimum mass/luminosity observed and an upper bound (function of the considered environment) represented by the boundary with the observed mass/luminosity overall behaviour. The mass distribution is then converted into a luminosity distribution through a standard mass-luminosity relationship.

Lorenzo, Zaninetti

2008-01-01

89

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at the center-of-mass energy of 7 and 8 TeV in 2011 and 2012, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about few hundred fb?1 expected for LHC running to 3000 fb?1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon systems, as well as improved triggers and data a...

Cinca, D; The ATLAS collaboration

2014-01-01

90

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at the center-of-mass energy of 7 TeV in 2011, the LHC is scheduled to deliver even more data in 2012 at 8 TeV. Meanwhile, plans are actively advancing for a series of upgrades, culminating roughly 10 years from now in the high luminosity LHC (HL-LHC) project, delivering of order five times the LHC nominal instantaneous luminosity along with luminosity levelling. The final goal is to extend the data set from about 300fb-1 expected for LHC running to 3000 fb-1 by around 2030. Current planning in ATLAS also has significant upgrades to the detector during the consolidation of the LHC to reach full LHC energy and further upgrades to accommodate running already beyond nominal luminosity this decade. The challenge of coping with HL-LHC instantaneous and integrated luminosity, along with the associated radiation levels, requires further major changes to the ATLAS detector. The designs are developing rapidly for an all-new inner-tracker, significant upgrades in the calorimeter and muon ...

Zhu, H; The ATLAS collaboration

2012-01-01

91

Luminosity Correlations, Luminosity Evolutions, and Radio Loudness of AGNs from Multiwavelength Observations  

Science.gov (United States)

The dichotomy of jet dominated versus accretion disk dominated AGNs or ``radio-loud'' vs ``radio-quiet'' quasars can be investigated by a simultaneous determination of the relative shape and evolution of the radio and optical luminosity functions, and the distribution of the radio loudness R defined as the ratio of radio to optical luminosities. This can be done from a multivariate data set containing observed fluxes, redshift, spectra, etc. We emphasize that when dealing with a multivariate data set it is imperative to first determine the true correlations, not those introduced by the observational selection effects, among the variables (e.g. Luminosity-luminosity, redshift-luminosity) before obtaining the individual distributions of the variables (e.g. Luminosity functions and density evolution). We use data from several sources including the SDSS (Data Release 7) and FIRST radio catalogs, with well defined optical and radio flux limits, and employ the non-parametric methods developed by Efron and Petrosian, designed to obtain unbiased correlations, distributions and evolution with redshift from data truncated due to observational biases. We determine the density and the luminosity evolutions in both wavebands, which shows significantly higher radio than optical luminosity evolution. From these we obtain true distribution of the radio loudness parameter which shows no sign of bi-modality and indicates that quasars were more radio loud at earlier epochs.

Petrosian, Vahe; Singal, Jack; Stawarz, Lukasz

2014-07-01

92

EU supports the LHC high-luminosity study  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

93

Investigations of the Parameter Space for the LHC Luminosity Upgrade  

CERN Document Server

Increasing the LHC luminosity by a factor of ten is a major challenge, especially for the beam-beam long-range interactions and even more for the magnet technology and insertion layout. To help identifying consistent solutions in this multi-dimensional constrained space, a parametric model of an LHC insertion was prepared, based on the present LHC layout, i.e. ?quadrupole first? and small crossing angle. The model deals with the layout, beam optics, beam-beam effect, superconductor margin and peak heat deposition in the coils. The approach is simplified to obtain a large gain in the optimization time. This study puts in evidence, as critical for the luminosity upgrade, the following actions: enlarging significantly the quadrupole aperture, moving the insertion towards the interaction point, using the highest available critical field superconductors and complementing the insertion with an early separation scheme. The luminosity reach can then be extended to 2×1035 cm-2s-1 while 1×1035 can be obtained with si...

Koutchouk, Jean-Pierre

2006-01-01

94

The DA?NE luminosity monitor  

International Nuclear Information System (INIS)

DA?NE, the Frascati ?-factory, is an e+/e- collider with 2 interaction points (IPs). The center of mass energy is 1020 MeV and the design luminosity 4.2x1030 cm-2 s-1 in single bunch mode and 5x1032 cm-2 s-1 in multibunch mode. Between the possible electromagnetic reactions at the interaction point, single bremsstrahlung (SB) has been selected for the luminosity measurement. The SB high counting rate allows real-time monitoring, which is very useful during machine tune-up and moreover the narrow peak of the SB angular distribution makes the counting rate almost independent from the beam position at the IP. A description of the experimental set-up, calibration results and luminosity measurements is presented

95

The DOe Run II Luminosity Monitor  

International Nuclear Information System (INIS)

The DOe Run II Luminosity Monitor consists of plastic scintillation detectors with fine-mesh photomultiplier readout that cover the range 2.7 < vertical bar ? vertical bar < 4.4 in pseudorapidity. The detector is designed to provide a precise measurement of the rate for non-diffractive inelastic collisions that is used to calculate the Tevatron luminosity at DOe. Excellent time-of-flight resolution allows a clean separation between beam-beam interactions and the principal background from beam halo. In addition, timing is used to measure the position of the primary interaction vertex and to detect multiple interactions. Accurate correction for multiple proton-antiproton interactions in a single beam crossing is essential for an accurate luminosity determination. Associated electronics provide a single-interaction trigger term for the DOe Level 1 trigger, and readout of the photomultiplier timing and pulse-height measurements

96

Energy and luminosity limits of hadron supercolliders  

Science.gov (United States)

Extending the frontiers of experimental high energy physics in a manner that maximizes discovery potential requires the building of accelerators of ever higher particle energies and luminosities. Both hadron and e(+)e(-) colliders have been proposed for this role. Based on a self-consistent computational model, this paper explores the features of hadron supercolliders beyond the SSC. The application of the presently available accelerator technologies embodied in the designs of the LHC and SSC to an ELOISATRON operating at 100 TeV per beam would yield a collider with a luminosity of 10(exp 34) cm(exp -2) s(exp -1). Even higher energies and luminosities are clearly possible. The paper concludes with an examination of the ultimate potential of synchrontron-based colliders to explore PeV energies.

Barletta, W. A.

1993-05-01

97

Title: Measuring Luminosity Dependent Quasar Clustering  

Science.gov (United States)

Whether luminous quasars reside in dark matter halos of the same mass and accrete at different rates, or, live in haloes of different masses, and accretion is near the Eddington limit, is still an open question. Here, we present measurements of the luminosity-dependence of quasar clustering, using data from the SDSS, 2SLAQ QSO and the new SDSS-III: BOSS Quasar surveys, allowing us to span 4 magnitudes in luminosity, at a given redshift. Using a cross-correlation technique, we measure the clustering of 3100 0.5luminosity, black-hole mass and Eddington ratio of the quasar sample.

Kirkpatrick, Jessica

2012-01-01

98

Energy and luminosity limits of hadron supercolliders  

International Nuclear Information System (INIS)

Extending the frontiers of experimental high energy physics in a manner that maximizes discovery potential requires the building accelerators of ever higher particle energies and luminosities. Both hadron and e+e- colliders have been proposed for this role. Based on a self-consistent computational model, this paper explores the features of hadron supercolliders beyond the SSC. The application of the presently available accelerator technologies embodied in the designs of the LHC and SSC to an ELOISATRON operating at 100 TeV per beam would yield a collider with a luminosity of 1034 cm-2 s-1. Even higher energies and luminosities are clearly possible. The paper concludes with an examination of the ultimate potential of synchrontron-based colliders to explore PeV energies

99

Energy and luminosity limits of hadron supercolliders  

Energy Technology Data Exchange (ETDEWEB)

Extending the frontiers of experimental high energy physics in a manner that maximizes discovery potential requires the building accelerators of ever higher particle energies and luminosities. Both hadron and e{sup +}e{sup {minus}} colliders have been proposed for this role. Based on a self-consistent computational model, this paper explores the features of hadron supercolliders beyond the SSC. The application of the presently available accelerator technologies embodied in the designs of the LHC and SSC to an ELOISATRON operating at 100 TeV per beam would yield a collider with a luminosity of 10{sup 34} cm{sup {minus}2} s{sup {minus}1}. Even higher energies and luminosities are clearly possible. The paper concludes with an examination of the ultimate potential of synchrontron-based colliders to explore PeV energies.

Barletta, W.A.

1993-05-01

100

The Local Luminosity Function at 25 Microns  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 $1/V_{max}$ e...

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

1998-01-01

 
 
 
 
101

Luminosity levelling techniques for the LHC  

CERN Document Server

We present the possibilities for doing luminosity levelling at the LHC. We explore the merits and drawbacks of each option and briefly discuss the operational implications. The simplest option is levelling with an offset between the two beams. Crab cavities may also be used for levelling, as may a squeezing of the beam. There is also the possibility of using the crossing angle in order to do luminosity levelling. All of these options are explored, for the LHC and other possible new projects, together with their benefits and drawbacks.

Muratori, B

2014-01-01

102

Luminosity of continuous beams with crossing angle  

International Nuclear Information System (INIS)

Since it appears difficult to reach a luminosity of even 10/sup 32/ cm/sup -2/ sec/sup -1/ with (p, p-bar) in a single ring if the number of events per bunch collision should not exceed unity, it seems appropriate to ask what could be done with two continuous beams in independent rings, ISR style. This subject was treated at some length previously, based on an optimization procedure developed earlier. In this paper, a different approach is taken by considering the length of the interaction diamond and the luminosity to be of primary importance and relating the other parameters to them

103

Intrinsic ?-ray luminosity, black hole mass, jet and accretion in Fermi blazars  

Science.gov (United States)

We have analysed a large sample of clean blazars detected by Fermi Large Area Telescope (LAT). Using the literature and calculation, we obtained intrinsic ?-ray luminosity excluding beaming effect, black hole mass, broad-line luminosity (used as a proxy for disc luminosity), jet kinetic power from `cavity' power and bulk Lorentz factor for parsec-scale radio emission, and studied the distributions of these parameters and relations between them. Our main results are as follows. (i) After excluding beaming effect and redshift effect, intrinsic ?-ray luminosity with broad-line luminosity, black hole mass and Eddington ratio have significant correlations. Our results confirm the physical distinction between BL Lacs and FSRQs. (ii) The correlation between broad-line luminosity and jet power is significant which supports that jet power has a close link with accretion. Jet power depends on both the Eddington ratio and black hole mass. We also obtain logLBLR ˜ (0.98 ± 0.07)logPjet for all blazars, which is consistent with the theoretical predicted coefficient. These results support that jets are powered by energy extraction from both accretion and black hole spin (i.e. not by accretion only). (iii) For almost all BL Lacs, Pjet > Ldisc; for most of FSRQs, Pjet < Ldisc. The `jet-dominance' (parametrized as P_jet/L_disc) is mainly controlled by the bolometric luminosity. Finally, the radiative efficiency of ?-ray and properties of TeV blazars detected by Fermi LAT were discussed.

Xiong, D. R.; Zhang, X.

2014-07-01

104

Academic Training - LHC luminosity upgrade: detector challenges  

CERN Multimedia

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 ...

Françoise Benz

2006-01-01

105

Recent improvements in luminosity at PEP  

International Nuclear Information System (INIS)

We will describe improvements which have led to new records for peak and average luminosity at PEP. Comparison of recent results with several earlier lattice and optical modifications shows rather good correlation with the predictions of a beam-beam simulation program

106

Precision luminosity measurements at the LHCb  

CERN Document Server

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...

LHCb Collaboration

2014-01-01

107

Transformation of Galaxy Morphology and Luminosity Classes  

CERN Document Server

We present a unified picture on the evolution of galaxy luminosity and morphology. Galaxy morphology is found to depend critically on the local environment set up by the nearest neighbor galaxy in addition to luminosity and the large scale density. When a galaxy is located farther than the virial radius from its closest neighbor, the probability for the galaxy to have an early morphological type is an increasing function only of luminosity and the local density due to the nearest neighbor ($\\rho_1$). The tide produced by the nearest neighbor is thought to be responsible for the morphology transformation toward the early type at these separations. When the separation is less than the virial radius, i.e. when $\\rho_1 > \\rho_{\\rm virial}$, its morphology depends also on the neighbor's morphology and the large-scale background density over a few Mpc scales ($\\rho_{20}$) in addition to luminosity and $\\rho_1$. The early type probability keeps increasing as $\\rho_1$ increases if its neighbor is an early type. But t...

Park, Changbom; Choi, Yun-Young

2007-01-01

108

Luminosity Measurement at the Compact Linear Collider  

CERN Document Server

The compact linear collider (CLIC) is a proposed high energy accelera- tor, planned to collide electrons with positrons at a maximal center-of-mass energy of 3 TeV, and a peak luminosity of 5.9·1034 cm?2s?1. Complementary to the large hadron collider, CLIC is to provide high precision measurements of both known and new physics processes. The required relative precision of luminosity measurement at the CLIC is 10?2. The measurement will be done by the luminosity calorimeter (Lumi- Cal), designed to measure the rate of low angles Bhabha scattering events, a process with well-known cross-section from electroweak theory. Beam-beam effects, which are of unprecedented intensity at the CLIC, influence the lumi- nosity spectrum shape and create a significant amount of background charge deposits in the LumiCal, thus setting a challenge on the requirement for precision. The ability of the LumiCal to provide accurate luminosity mea- surement depends on its ability to perform accurate energy reconstruction of Bhab...

Schwartz, Rina; Levy, Aharon

109

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.)

110

Luminosity measurement method for the LHC: Event selection and absolute luminosity determination  

International Nuclear Information System (INIS)

In our earlier papers Krasny et al. [1,2] have proposed a new luminosity measurement method which uses lepton pairs produced in peripheral collisions of the LHC beam particles, and identified the requirements for a new, specialized luminosity detector which is indispensable for their efficient on-line selection. In this paper we use the base-line detector model, with no precise timing capabilities, to evaluate the statistical and systematic accuracy of the method. We propose the complete event selection procedure and demonstrate that it allows to collect a sufficiently large sample of e+e? pairs to achieve a better than 1% statistical accuracy of the luminosity measurement over less than one-month-long running time intervals. We argue that the absolute luminosity measurement systematic errors can be kept below 1%. The proposed method can be directly applied to the LHC running periods for which the machine instantaneous luminosity does not exceed the L=1033s?1cm?2 value. Two ways extending the method to the large pile-up periods corresponding to higher instantaneous luminosities are proposed

111

Solar gravitational energy and luminosity variations  

CERN Document Server

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...

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

2009-01-01

112

Optimization of integrated luminosity in the Tevatron  

Energy Technology Data Exchange (ETDEWEB)

We present the strategy which has been used recently to optimize the performance of the Fermilab Tevatron proton-antiproton collider. We use a relatively simple heuristic model based on the antiproton production rate, which optimizes the number of antiprotons in a store in order to maximize the integrated luminosity. A store is terminated as soon as the target number of antiprotons is reached and the Tevatron quickly resets to load another store. Since this procedure was implemented, the integrated luminosity has improved by {approx} 35%. Other recent operational improvements include decreasing the shot setup time, and reducing beam-beam effects by making the proton and antiproton brightness more compatible, for example by scraping protons to smaller emittances.

Gattuso, C.; Convery, M.; Syphers, M.; /Fermilab

2009-04-01

113

Silicon tracking at high luminosity colliders  

International Nuclear Information System (INIS)

Future applications of silicon detectors at high luminosity colliders envision their use after fluences of 1014-1015 minimum ionizing particles/cm2. This requires facing a number of special problems: large bias voltages on the detector, large leakage currents, and thermal instabilities. We present some of the relevant results on these problems as well as a brief review of some of the presently planned detectors

114

Luminosity of photon-photon colliders  

International Nuclear Information System (INIS)

By using a Monte Carlo code, we estimated a realistic photon beam profile and luminosity as well as a beam background of the photon-photon collider. We also indicated a possibility of generating higher energy photons exceeding the threshold of e+e- pair creation, which was previously considered to be impossible due to serious background from e+e- pairs created by the collision of the backscattered photon and a laser photon. (author)

115

Luminosity Measurement at the Large Hadron Collider  

CERN Document Server

Two novel methods of measuring the luminosity delivered to the ATLAS Experiment at the CERN Large Hadron Collider experiments are presented. The production of $\\mu^{+}\\mu^{-}$ pair via two photon interactions and single $W^{\\pm}/Z^{0}$ boson production are evaluated as methods for the measurement and monitoring of the proton-proton luminosity at the LHC. The characteristics of the $\\mu^{+}\\mu^{-}$ pairs from coherent $\\gamma \\gamma$ interactions are examined for both matrix element and equivalent photon based monte carlo generators with subsequent simulation of the ATLAS detector effects. The application of specific kinematic and vertex fit requirements is shown to offer a strong method of isolating signal from background and in turn yield an accurate offline measurement of the delivered luminosity via the pure QED process. The choice of kinematic cuts is shown to reduce the overall uncertainty in the method by limiting the size of corrections to the two photon interaction cross section to the level of 1\\%. B...

Caron, B L

2006-01-01

116

Luminosity Evolution of Gamma-ray Pulsars  

CERN Document Server

We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resultant gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial ten thousand years, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater but increases less rapidly than what a light element envelope has. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. Th...

Hirotani, Kouichi

2013-01-01

117

Intrinsic $\\gamma$-ray luminosity, black hole mass, jet and accretion in Fermi blazars  

CERN Document Server

We have analyzed a large sample of clean blazars detected by Fermi Large Area Telescope (LAT). Using literature and calculation, we obtained intrinsic $\\gamma$-ray luminosity excluding beaming effect, black hole mass, broad-line luminosity (used as a proxy for disk luminosity), jet kinetic power from "cavity" power and bulk Lorentz factor for parsec-scale radio emission, and studied the distributions of these parameters and relations between them. Our main results are as follows. (i) After excluding beaming effect and redshift effect, intrinsic $\\gamma$-ray luminosity with broad line luminosity, black hole mass and Eddington ratio have significant correlations. Our results confirm the physical distinction between BL Lacs and FSRQs. (ii) The correlation between broad line luminosity and jet power is significant which supports that jet power has a close link with accretion. Jet power depends on both the Eddington ratio and black hole mass. We also obtain $LogL_{\\rm BLR}\\sim(0.98\\pm0.07)Log P_{\\rm jet}$ for all ...

Xiong, Dingrong

2014-01-01

118

The cross-correlation between galaxies of different luminosities and Colors  

CERN Document Server

We study the cross-correlation between galaxies of different luminosities and colors, using a sample selected from the SDSS Dr 4. Galaxies are divided into 6 samples according to luminosity, and each of these samples is divided into red and blue subsamples. Projected auto-correlation and cross-correlation is estimated for these subsample. At projected separations r_p > 1\\mpch, all correlation functions are roughly parallel, although the correlation amplitude depends systematically on luminosity and color. On r_p 1\\mpch for each subsample using its auto-correlation function and cross-correlation functions. The relative bias factors obtained from different methods are similar. For blue galaxies the luminosity-dependence of the relative bias is strong over the luminosity range probed (-23.0luminosities below L^*. To examine whether a significant stochastic/nonlinear component exists in the bias relation, we study the...

Wang, Y; Mo, H J; Van den Bosch, F C; Wang, Yu; Yang, Xiaohu; Bosch, Frank C. van den

2007-01-01

119

The host galaxies of low luminosity quasars at high redshift  

CERN Document Server

We present VLT/ISAAC near-infrared imaging of the host galaxies of 15 low luminosity quasars at 1 < z < 2. This work complements our studies to trace the cosmological evolution of the host galaxies of high luminosity quasars. The radio-loud (RLQ) and radio-quiet (RQQ) quasars have similar distribution of redshift and luminosity, and together the high and low luminosity quasars cover a large range of the quasar luminosity function. Both RLQ and RQQ hosts resemble massive inactive ellipticals undergoing passive evolution. However, RLQ hosts are systematically more luminous than RQQ hosts, as also found for the high luminosity quasars. The difference in the host luminosity remains the same from z = 2 to z = 0. For the entire set of quasars, we find a correlation between the nuclear and the host luminosities, albeit with a large scatter. The correlation is less apparent for the RQQs than for the RLQs.

Kotilainen, J K; Treves, A; Uslenghi, M

2005-01-01

120

Physics program of ALFA and precision luminosity measurement in ATLAS  

CERN Document Server

Physics program of ALFA: absolute luminosity & total cross section measurements is presented together with other ATLAS luminosity measurement algorithms. Additionaly to this a possibility to measure single diffraction and exclusive processes is shown.

Sykora, T; The ATLAS collaboration

2011-01-01

 
 
 
 
121

Physics program of ALFA and precision luminosity measurement in ATLAS  

CERN Document Server

Physics program of ALFA: absolute luminosity & total cross section measurements is presented together with other ATLAS luminosity measurement algorithms. Additionaly to this a possibility to measure single diffraction and exclusive processes is shown.

Sykora, T; The ATLAS collaboration

2012-01-01

122

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

Energy Technology Data Exchange (ETDEWEB)

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 {approx}< 21.8 quasars are selected over an area of 2236 deg{sup 2}, with confirmed spectroscopic redshifts between 2.2 < z < 3.5, filling in a key part of the luminosity-redshift plane for optical quasar studies. The completeness of the survey is derived through simulated quasar photometry, and this completeness estimate is checked using a sample of quasars selected by their photometric variability within the BOSS footprint. We investigate the level of systematics associated with our quasar sample using the simulations, in the process generating color-redshift relations and a new quasar K-correction. We probe the faint end of the QLF to M{sub i} (z = 2.2) Almost-Equal-To -24.5 and see a clear break in the QLF at all redshifts up to z = 3.5. A log-linear relation (in log {Phi}* - 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 {approx}2.6 while {Phi}* declines by a factor of {approx}8. At z {approx}< 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.

Ross, Nicholas P.; White, Martin; Bailey, Stephen [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 92420 (United States); McGreer, Ian D. [Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Richards, Gordon T. [Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Palanque-Delabrouille, Nathalie; Yeche, Christophe [CEA, Centre de Saclay, IRFU, F-91191 Gif-sur-Yvette (France); Strauss, Michael A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Anderson, Scott F. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Shen, Yue; Swanson, Molly E. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Aubourg, Eric [APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cite (France); Bizyaev, Dmitry; Brewington, Howard; Brinkmann, J. [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); Bovy, Jo [Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540 (United States); DeGraf, Colin; Di Matteo, Tiziana, E-mail: npross@lbl.gov [McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); and others

2013-08-10

123

NLC Luminosity as a Function of Beam Parameters  

CERN Document Server

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.

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

2002-01-01

124

Variations of Core Luminosity and Solar Neutrino Fluxes  

CERN Document Server

In a Dynamic Solar Model (DSM) the temperature dependences of the pp cycle neutrinos will be different from the ones determined by solar model calculations with the luminosity constraint. Instead of the usual neutrino fluxes pp ~ T^{-1/2}, Be ~ T^8, B ~ T^{18}, we determined by the nuclear reaction rates formulas pp ~ T^{4.2}, Be ~ T^{-1/2}, B ~ T^{13.5}, for $\\tau < 10^2$ years. These latter relations have high significance at estimating the uncertainties of the solar central temperatures without assuming the luminosity constraint. Although the purely astrophysical solutions seem to be ruled out, this is not the case for a model in which astrophysical effects are included besides the neutrino oscillations. Therefore a combined, DSM+MSW model is suggested to calculate the observed solar neutrino fluxes. The combined SSM+MSW fits to the rates+spectra+D/N changes give a bad fit to the total rates, indicating the need to include the astrophysical factors besides the MSW effect. The DSM suggest that the core d...

Grandpierre, A

2002-01-01

125

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

CERN Document Server

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...

Revnivtsev, M G; Suleimanov, V F

2014-01-01

126

Low Luminosity Activity in Hickson Compact Groups  

Science.gov (United States)

With the aim of studying the influence of environment on the nuclear activity of galaxies, we have selected a well defined sample of 65 Compact Groups of galaxies with concordant redshift in the Hickson Catalogue [5]. In this proceeding, we present the results of the classification of nuclear activity for 42 galaxies, based on newly obtained spectral observations. In this subsample, 71% of the galaxies turned out to have emission lines in their nuclei. 73% of these emission-line galaxies were found to have characteristics consistent with low luminosity AGN (LLAGN), which makes compact groups extremely rich in such objects.

Martinez, M. A.; Del Olmo, A.; Perea, J.; Coziol, R.

127

Galaxy luminosity function: a new analytic expression  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

128

The Mid-Infrared Color-Luminosity Relation and the Local 12 micron Luminosity Function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We have established a model to systematically estimate the contribution of the mid-infrared emission features between 3 and 11.6 micron to the IRAS in-band fluxes, using the results of ISO PHT-S observation of 16 galaxies by Lu et al. (1997). The model is used to estimate more properly the k-corrections for calculating the restframe 12 and 25 micron fluxes and luminosities of IRAS galaxies. We have studied the 12-25 micron color-luminosity relation for a sample of galaxies s...

Fang, Fan; Shupe, David L.; Xu, Cong; Hacking, Perry B.

1998-01-01

129

Far-infrared luminosities of Markarian starburst galaxies  

International Nuclear Information System (INIS)

Total far-infrared luminosities have been calculated from measured IRAS fluxes for a sample of optically selected galaxies and for a comparison sample of spiral galaxies. The starburst galaxies are notably more luminous in the far-infrared and have higher dust color temperatures than the comparison galaxies. The far-infrared light dominates the total luminosity of the starburst galaxies, and a significant amount of dust must be present. The far-infrared emission correlates well with total blue luminosity, nuclear blue luminosity, and nuclear H-alpha luminosity. The dust that produces the far-infrared light is probably heated predominantly by B rather than by O stars. 30 references

130

LHC Report: A new luminosity record  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

131

Low-luminosity AGN and Normal Galaxies  

CERN Document Server

Low-luminosity AGN (with X-ray luminosity < 1e42 ergs/s) far outnumber ordinary AGN, and are therefore perhaps more relevant to our understanding of AGN phenomena and the relationship between AGN and host galaxies. Many normal galaxies harbor LINER and starburst nuclei, which, together with LLAGN, are a class of ``low-activity'' galaxies that have a number of surprisingly similar X-ray characteristics, despite their heterogenous optical classification. This strongly supports the hypothesis of an AGN-starburst connection. Further, X-ray observations of normal galaxies without starburst or AGN-like activity in their nuclei offer opportunities to study populations of X-ray binaries, HII regions, and warm or hot ISM under different conditions than is often the case in the Milky Way. The results of recent X-ray observations of these types of galaxies are reviewed, and what we hope to learn about both nearby and high redshift galaxies of each type from observations with forthcoming and planned satellites is disc...

Ptak, A

2000-01-01

132

The host galaxies of low luminosity quasars at high redshift  

Science.gov (United States)

We present VLT/ISAAC near-infrared imaging of the host galaxies of 15 low luminosity quasars at 1 RLQ) and radio-quiet (RQQ) quasars have similar distribution of redshift and luminosity, and together the high and low luminosity quasars cover a large range of the quasar luminosity function. Both RLQ and RQQ hosts resemble massive inactive ellipticals undergoing passive evolution. However, RLQ hosts are systematically more luminous than RQQ hosts, as also found for the high luminosity quasars. The difference in the host luminosity remains the same from z = 2 to 0. For the entire set of quasars, we find a correlation between the nuclear and the host luminosities, albeit with a large scatter. The correlation is less apparent for the RQQs than for the RLQs.

Kotilainen, J. K.; Falomo, R.; Treves, A.; Uslenghi, M.

2006-11-01

133

The bright end of the QSO luminosity function  

CERN Document Server

We have analysed the optical luminosity-redshift distribution properties of bright QSOs, using a new large sample from the Hamburg/ESO survey. The sample provides insight into the hitherto poorly sampled bright tail of the luminosity function, allowing to monitor its evolution with redshift up to $z\\approx 3$. The slope increases significantly towards higher $z$, inconsistent with the predictions of pure luminosity evolution, but also with other recently proposed parameterisations. This phenomenon is opposite to what would be expected from gravitational lensing, showing that magnification bias does not significantly distort the QSO luminosity function within the redshift range covered. The space density of high-luminosity QSOs continues to increase up to the high-redshift limit of the survey, without indication of reduced evolution above $z\\simeq 2$. The sample also permits an improved estimate of the local ($z\\approx 0$) luminosity function of QSOs and bright Seyfert~1 nuclei, over the luminosity range $-27\\...

Wisotzki, L

2000-01-01

134

Ideas for a high luminosity muon physics detector with complete particle identification  

International Nuclear Information System (INIS)

Modifications of the existing EMC-NA9 spectrometer at the SPS muon beam by using a Time Projection Chamber (TPC) as vertex-detector and Ring Mage Cerenkov (RICH) counters allow at least a factor 5 increase in luminosity and provide complete hadron identification. The compactness of the new detectors gives space for future 4? coverage for neutral particle detection. (orig.)

135

INFRARED CLASSIFICATION AND LUMINOSITIES FOR DUSTY ACTIVE GALACTIC NUCLEI AND THE MOST LUMINOUS QUASARS  

International Nuclear Information System (INIS)

Mid-infrared spectroscopic measurements from the Infrared Spectrometer (IRS) on Spitzer are given for 125 hard X-ray active galactic nuclei (AGNs; 14-195 keV) from the Swift Burst Alert Telescope (BAT) sample and for 32 AGNs with black hole masses (BHMs) from reverberation mapping. The 9.7 ?m silicate feature in emission or absorption defines an infrared AGN classification describing whether AGNs are observed through dust clouds, indicating that 55% of the BAT AGNs are observed through dust. The mid-infrared dust continuum luminosity is shown to be an excellent indicator of intrinsic AGN luminosity, scaling closely with the hard X-ray luminosity, log ?L?(7.8 ?m)/L(X) = –0.31 ± 0.35, and independent of classification determined from silicate emission or absorption. Dust luminosity scales closely with BHM, log ?L?(7.8 ?m) = (37.2 ± 0.5) + 0.87 log BHM for luminosity in erg s–1 and BHM in M?. The 100 most luminous type 1 quasars as measured in ?L?(7.8 ?m) are found by comparing Sloan Digital Sky Survey (SDSS) optically discovered quasars with photometry at 22 ?m from the Wide-Field Infrared Survey Explorer (WISE), scaled to rest frame 7.8 ?m using an empirical template determined from IRS spectra. The most luminous SDSS/WISE quasars have the same maximum infrared luminosities for all 1.5 IR = 1014.4 L?. Comparing with ub>. Comparing with dust-obscured galaxies from Spitzer and WISE surveys, we find no evidence of hyperluminous obscured quasars whose maximum infrared luminosities exceed the maximum infrared luminosities of optically discovered quasars. Bolometric luminosities Lbol estimated from rest-frame optical or ultraviolet luminosities are compared to LIR. For the local AGN, the median log LIR/Lbol = –0.35, consistent with a covering factor of 45% for the absorbing dust clouds. For the SDSS/WISE quasars, the median log LIR/Lbol = 0.1, with extremes indicating that ultraviolet-derived Lbol can be seriously underestimated even for type 1 quasars.

136

Galaxy cluster X-ray luminosity scaling relations from a representative local sample (REXCESS)  

Science.gov (United States)

We examine the X-ray luminosity scaling relations of 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS). The objects are selected only in X-ray luminosity, optimally sampling the cluster luminosity function. Temperatures range from 2 to 9 keV, and there is no bias toward any particular morphological type. To reduce measurement scatter we extract pertinent values in an aperture corresponding to R500, estimated using the tight correlation between YX (the product of gas mass and temperature) and total mass. The data exhibit power law relations between bolometric X-ray luminosity and temperature, YX and total mass, all with slopes that are significantly steeper than self-similar expectations. We examine the possible causes for the steepening, finding that structural variations have little effect and that the primary driver appears to be a systematic variation of the gas content with mass. Scatter about the relations is dominated in all cases by the presence of cool cores. The natural logarithmic scatter about the raw X-ray luminosity-temperature relation is about 70 per cent, and about the X-ray luminosity-YX relation it is 40 per cent. Systems with more morphological substructure show similar scatter about scaling relations than clusters with less substructure, due to the preponderance of cool core systems in the regular cluster subsample. Cool core and morphologically disturbed systems occupy distinct regions in the residual space with respect to the best fitting mean relation, the former lying systematically at the high luminosity side, the latter lying systematically at the low luminosity side. Simple exclusion of the central regions serves to reduce the scatter about the scaling relations by more than a factor of two. The scatter reduces by a similar amount with the use of the central gas density as a third parameter. Using YX as a total mass proxy, we derive a Malmquist bias-corrected local luminosity-mass relation and compare with other recent determinations. Our results indicate that luminosity can be a reliable mass proxy with controllable scatter, which has important implications for upcoming all-sky cluster surveys, such as those to be undertaken with Planck and eROSITA, and ultimately for the use of the cluster population for cosmological purposes.

Pratt, G. W.; Croston, J. H.; Arnaud, M.; Böhringer, H.

2009-05-01

137

Absolute luminosity measurement at LHCb with beam-gas imaging  

International Nuclear Information System (INIS)

A novel technique to measure the absolute luminosity at the Large Hadron Collider (LHC) using beam-gas interactions has been successfully used in the LHCb experiment. The Beam-Gas Imaging method (BGI) has the potential to surpass the accuracy of the commonly used ''van der Meer scan'' method (VDM) but has been limited by the low statistic so far. A new device has been installed in the LHCb experiment to increase the pressure around the interaction point by mean of gas injection during dedicated fills. This talk presents the principles of the gas injection and the improvements expected with the increased pressure. Furthermore the gas injection will now help to evaluate the so-called ghost charges and also to better quantify the intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

138

60 micron luminosity evolution of rich clusters of galaxies  

International Nuclear Information System (INIS)

The average 60-micron flux has been determined for a collection of optically selected galaxy clusters at redshifts ranging from 0.30 to 0.92. The result, 26 mJy per cluster, represents the faintest flux determination known of using the IRAS data base. The flux from this set of clusters has been compared to the 60-micron flux from a sample of nearby galaxy clusters. It is found that the far-infrared luminosity evolution in cluster galaxies can be no more than a factor of 1.7 from z = 0.4 to the present epoch. This upper limit is close to the evolution predicted for simple aging of the stellar populations. Additional processes such as mergers, cannibalism, or enhanced rates of starbursts appear to occur at a low enough level that they have little influence on the far-infrared emission from clusters over this redshift range. 38 refs

139

High-energy gamma-ray afterglows from low-luminosity gamma-ray bursts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The observations of gamma-ray bursts (GRBs) such as 980425, 031203 and 060218, with luminosities much lower than those of other classic bursts, lead to the definition of a new class of GRBs -- low-luminosity GRBs. The nature of the outflow responsible for them is not clear yet. Two scenarios have been suggested: one is the conventional relativistic outflow with initial Lorentz factor of order of $\\Gamma_0\\ga 10$ and the other is a trans-relativistic outflow with $\\Gamma_0\\si...

He, Hao-ning; Wang, Xiang-yu; Yu, Yun-wei; Meszaros, Peter

2009-01-01

140

The spectral index-luminosity relationship for steep-spectrum cores in extragalactic radio sources  

International Nuclear Information System (INIS)

The spectral index-luminosity relationship has been investigated for steep-spectrum cores in galaxies and quasars, and it is found that the sample of galaxies supports earlier suggestions of a strong correlation, while there is weak evidence for a similar relationship for the quasars. It is shown that a strong spectral index-luminosity correlation can be used to set an upper limit to the velocities of the radio-emitting material which is expelled from the nucleus in the form of collimated beams or jets having relativistic bulk velocities. The data on cores in galaxies indicate that the Lorentz factors of the radiating material are less than about 2. (author)

 
 
 
 
141

Spherical aberrations in the thermal-wave model for luminosity estimates in particle accelerators  

International Nuclear Information System (INIS)

An approach for estimating the luminosity in linear colliders in the presence of spherical aberrations is developed within the framework of the recently proposed thermal-wave model for relativistic-charged-particle-beam propagation. By taking into account a quadrupolelike lens with octupole deviations, the transverse beam motion is governed by a two-dimensional Schroedinger-like equation, with an anharmonic potential. To first order in perturbation theory and in the thin-lens approximation, we analytically find the transverse beam density, the spot size, and the luminosity reduction factor at the interaction point in terms of the initial conditions. Some numerical estimates are also given

142

Operation of the Run IIB D0 Luminosity System and Determination of the Run IIB Luminosity Constant  

Energy Technology Data Exchange (ETDEWEB)

The luminosity system is an integral part of the D0 detector that must be properly maintained to provide accurate luminosity measurements for physics analysis. After the addition of a readout layer to the silicon vertex detector in 2006, it was necessary to re-calculate the effective inelastic cross section to which the luminosity monitor is sensitive. The preliminary analysis showed that the luminosity constant did not change with the addition of the extra layer of silicon. A full study of the revised luminosity constant including a complete analysis of systematic uncertainties has been completed. The luminosity constant was determined to be {sigma}{sub eff} = 48.3 {+-} 1.9 {+-} 0.6 mb, which reduces the D0 contribution to the luminosity measurement uncertainty by almost 3%.

Prewitt, Michelle Victoria; /Rice U.

2010-04-01

143

Key to the Mystery of Dark Energy: Corrected Relationship between Luminosity Distance and Redshift  

Directory of Open Access Journals (Sweden)

Full Text Available A new possible explanation to the luminosity distance (DL and redshift (Z measurements of type Ia supernovae (SNeIa is developed. Instead of modifying the theory of general relativity or the Friedmann equation of cosmology with an extra scalar ?eld or unknown energy component (e.g., dark energy, we re-examine the relationship between the luminosity distance and the cosmological redshift (DL Z. It is found that the DL Z relation previously applied to connect the cosmological model with the measured SNeIa data is only valid for nearby objects with Z ? 1. The luminosity distances of all distant SNela with Z ? 1 had been underestimated. The newly derived DL Z relation has an extra factor p 1 + Z, with which the cosmological model exactly explains all the SNeIa measurements without dark energy. This result indicates that our universe has not accelerated and does not need dark energy at all.

Zhang T. X.

2013-07-01

144

Superconducting Quadrupole Prototype for the ISR high luminosity (low beta) insertion  

CERN Multimedia

In colliders, smaller beam cross-section means higher luminosity. Beam-size being proportional to the square-root of the "beta function" value, a small beta means small beam size, hence high luminosity. In 1973 a study was launched on low-beta insertions using superconducting quadrupole magnets, which focus beams to very small sizes at the beam crossing points . In 1976 the first prototype of a superconducting quadrupole was tested. Here we see Theodor Tortschanoff with the prototype of 1.25 m magnetic length. Manufacture of 8 quadrupoles (4 of L=1.15 m, 4 of L=0.65 m) began at Alsthom in 1978. They were installed at intersection I8 of the ISR, enhancing luminosity there by a factor 7 until final low-beta operation in December 1983. For details see "Yellow Report" CERN 76-16. See also pictures 7702307, 7702308, 7702182,7510214X,7510217X.

1977-01-01

145

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

CERN Document Server

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.

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

146

ATLAS Tile Calorimeter Readout Electronics Upgrade Program for the High Luminosity LHC  

CERN Document Server

The Tile Calorimeter (TileCal) is the hadronic calorimeter covering the most central region of the ATLAS experiment at LHC. The TileCal readout consists of about 10000 channels. The ATLAS upgrade program is divided in three phases: The Phase 0 occurs during 2013-2014 and prepares the LHC to reach peak luminosities of 1034 cm2s-1; Phase 1, foreseen for 2018-1019, prepares the LHC for peak luminosity up to 2-3 x 1034 cm2s-1, corresponding to 55 to 80 interactions per bunch-crossing with 25 ns bunch interval; and Phase 2 is foreseen for 2022-2023, whereafter the peak luminosity will reach 5-7 x 1034 cm2s-1 (HL-LHC). With luminosity leveling, the average luminosity will increase with a factor 10. The main TileCal upgrade is focused on the HL-LHC period. The upgrade aims at replacing the majority of the on- and off-detector electronics so that all calorimeter signals are directly digitized and sent to the off-detector electronics in the counting room. All new electronics must be able to cope with the increased rad...

Cerqueira, A S; The ATLAS collaboration

2013-01-01

147

The GRB luminosity function in the internal shock model confronted to observations  

CERN Document Server

We compute the expected luminosity function of GRBs in the context of the internal shock model. We assume that GRB central engines generate relativistic outflows characterized by the respective distributions of injected kinetic power Edot and contrast in Lorentz factor Kappa = Gamma_max/Gamma_min. We find that if the distribution of contrast extends down to values close to unity (i.e. if both highly variable and smooth outflows can exist) the luminosity function has two branches. At high luminosity it follows the distribution of Edot while at low luminosity it is close to a power law of slope -0.5. We then examine if existing data can constrain the luminosity function. Using the log N - log P curve, the Ep distribution of bright BATSE bursts and the XRF/GRB ratio obtained by HETE2 we show that single and broken power-laws can provide equally good fits of these data. Present observations are therefore unable to favor one form of the other. However when a broken power-law is adopted they clearly indicate a low ...

Zitouni, H; Mochkovitch, R; Zerguini, T H

2010-01-01

148

Lenticular Galaxy Formation - Possible Luminosity Dependence  

CERN Document Server

We investigate the correlation between the bulge effective radius (r_e) and disk scale length (r_d), in the near-infrared K band for lenticular galaxies in the field and in clusters. We find markedly different relations between the two parameters as a function of luminosity. Lenticulars with total absolute magnitude fainter than M_T = -24.5 show a positive correlation, in line with predictions of secular formation processes for the pseudo bulges of late-type disk galaxies. But brighter lenticulars with M_T < -24.5 show an anti-correlation, indicating that they formed through a different mechanism. The available data are insufficient to reliably determine the effect of galaxy environment on this correlation.

Barway, S; Wadadekar, Y; Ravikumar, C D; Mayya, Y D; Barway, Sudhanshu; Kembhavi, Ajit; Wadadekar, Yogesh

2007-01-01

149

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

150

A New Analytic Galactic Luminosity Profile Function  

CERN Document Server

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.

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

2014-01-01

151

The Morphological Type Dependence of K-band Luminosity Functions  

CERN Document Server

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 peaked with a fall off at both high and low luminosities. However, each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall K-band luminosity density in the local universe, and by inference, the stellar mass density as well.

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

2009-01-01

152

Seeking the Epoch of Maximum Luminosity for Dusty Quasars  

CERN Document Server

Infrared luminosities vLv(7.8 um) arising from dust reradiation are determined for Sloan Digital Sky Survey (SDSS) quasars with 1.4 ~ 3 with maximum luminosity vLv(7.8 um) >~ 10^{47} erg per s; luminosity functions show one quasar per cubic Gpc having vLv(7.8 um) > 10^{46.6} erg per s for all 2 5 magnitudes of ultraviolet extinction. We present a new summary of obscured quasars discovered with the Spitzer Infrared Spectrograph and determine the infrared luminosity function of these obscured quasars at z ~ 2.1. This is compared with infrared luminosity functions of optically discovered, unobscured quasars in the SDSS and in the AGN and Galaxy Evolution Survey. The comparison indicates comparable numbers of obscured and unobscured quasars at z ~ 2.1 with a possible excess of obscured quasars at fainter luminosities.

Vardanyan, Valeri; Sargsyan, Lusine

2014-01-01

153

Evolution of the luminosity function of extragalactic objects  

Science.gov (United States)

A nonparametric procedure for determination of the evolution of the luminosity function of extragalactic objects and use of this for prediction of expected redshift and luminosity distribution of objects is described. The relation between this statistical evolution of the population and their physical evolution, such as the variation with cosmological epoch of their luminosity and formation rate is presented. This procedure when applied to a sample of optically selected quasars with redshifts less than two shows that the luminosity function evolves more strongly for higher luminosities, indicating a larger quasar activity at earlier epochs and a more rapid evolution of the objects during their higher luminosity phases. It is also shown that absence of many quasars at redshifts greater than three implies slowing down of this evolution in the conventional cosmological models, perhaps indicating that this is near the epoch of the birth of the quasar (and galaxies).

Petrosian, V.

1985-01-01

154

Physics program of ALFA and precision luminosity measurement in ATLAS  

CERN Document Server

ALFA - Absolute Luminosity For ATLAS - is a system of tracker-type detectors which primary goal is to measure absolute luminosity. In the talk the principle of the measurement, the summary of planned physics program and the actual status of the ALFA detector installation are given. The second part of the talk is devoted to a short overview of complementary luminosity measurements used by ATLAS collaboration.

Sykora, T; The ATLAS collaboration

2011-01-01

155

Transformation of Morphology and Luminosity Classes of the SDSS Galaxies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a unified picture on the evolution of galaxy luminosity and morphology. Galaxy morphology is found to depend critically on the local environment set up by the nearest neighbor galaxy in addition to luminosity and the large scale density. When a galaxy is located farther than the virial radius from its closest neighbor, the probability for the galaxy to have an early morphological type is an increasing function only of luminosity and the local density due to the ne...

Park, Changbom; Gott Iii, J. Richard; Choi, Yun-young

2007-01-01

156

Luminosities of recycled radio pulsars in globular clusters  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Using Monte Carlo simulations, we model the luminosity distribution of recycled pulsars in globular clusters as the brighter, observable part of an intrinsic distribution and find that the observed luminosities can be reproduced using either log-normal or power-law distributions as the underlying luminosity function. For both distributions, a wide range of model parameters provide an acceptable match to the observed sample, with the log-normal function providing statisticall...

Bagchi, Manjari; Lorimer, Duncan R.; Chennamangalam, Jayanth

2011-01-01

157

Pure luminosity evolution hypothesis for QSOs from luminosity functions to synthetic catalogues  

CERN Document Server

This paper describes the simulation of realistic Monte-Carlo extragalactic catalogues, aimed at comparing the behaviour of cosmological tests versus input parameters. QSO catalogues are built on a Luminosity Function derived from data through suitable computation of individual maximum volumes in complete (but magnitude- and redshift-limited) samples requiring neither of redshift nor of apparent magnitude histogram. The values of the evolution parameter are derived for various cosmologies, corresponding to =1/2 in the sample of 400 Ultra-Violet Excess (UVX) QSOs (Boyle et al 1990). The various luminosity functions are compared, both for the whole sample and in redshift bins. An evolution characteristic time is defined and computed, depending strongly on the cosmology, but practically constant when expressed in terms of the age of the Universe. Algorithms are given for producing unbiased or biased catalogues based on the null hypothesis that the objects are uniformly distributed in volume but suffer Pure Lumino...

Mathez, G; Mellier, Y; Bonnet, H; Lachièze-Rey, M

1995-01-01

158

Luminosity Measurement Using Cherenkov Integrating Detector (LUCID) in ATLAS  

CERN Document Server

LUCID (LUminosity measurement using Cherenkov Integrating Detector) is a Cherenkov counter designed to monitor the luminosity in the ATLAS experiment. Since the final accuracy of the measurement of some crucial physical quantities in the LHC program will depend on the precision of the luminosity measurement, it is mandatory to push the latter to its best. This in turn implies the need to monitor the beam conditions. In this paper an overview of LUCID is given. After a description of the detector, an insight into the luminosity measurement strategy in ATLAS is given, as well as a description of the calibration strategy of LUCID.

Caforio, D

2008-01-01

159

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

160

The Abundance of Low-Luminosity Ly? Emitters at High Redshift  

Science.gov (United States)

We derive the luminosity function of high-redshift Ly?-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 nine clusters, consistent with magnification factors generally greater than 10 for the redshift range 4.5account our varying intrinsic Ly? line sensitivity as a function of wavelength and sky position. By virtue of the strong magnification factor, we provide constraints on the Ly? luminosity function to unprecedented limits of 1040 ergs s -1, corresponding to a star formation rate of 0.01 Msolar yr-1. Our cumulative z~=5 Ly? luminosity function is consistent with a power-law form n(>L)~L-1 over 1041-1042.5 ergs s-1. 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. Data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

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

2004-05-01

 
 
 
 
161

The Luminosities of the Coldest Brown Dwarfs  

CERN Document Server

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 ...

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

2014-01-01

162

The Red Giant Branch Luminosity Function Bump  

CERN Document Server

We present observational estimates of the magnitude difference between the luminosity function RGB bump and the HB (Delta(bump-zahb)), and of star counts in the bump region (R_bump), for a sample of 54 Galactic globular clusters (GCs) observed by the HST. The large sample of stars resolved in each cluster, and the high photometric accuracy of the data allowed us to detect the bump also in a number of metal poor clusters. To reduce the photometric uncertainties, empirical values are compared with theoretical predictions obtained from a set of updated canonical stellar evolution models which have been transformed directly into the HST flight system. We found an overall qualitative agreement between theory and observations. Quantitative estimates of the confidence level are hampered by current uncertainties on the GCs metallicity scale, and by the strong dependence of Delta(bump-zahb) on the cluster metallicity. In case of the R_bump parameter, which is only weakly affected by the metallicity, we find a very goo...

Riello, M; Piotto, G; Recio-Blanco, A; De Angeli, F; Salaris, M; Pietrinferni, A; Bono, G; Zoccali, M

2003-01-01

163

Multiwavelength Characteristics of Period-Luminosity Relations  

CERN Document Server

We present a physically motivated explanation for the observed, monotonic increase in slope, and the simultaneous (and also monotonic) decrease in the width/scatter of the Leavitt Law (the Cepheid Period-Luminosity (PL) relation) as one systematically moves from the blue and visual into the near and mid-infared. We calibrate the wavelength-dependent, surface-brightness sensitivities to temperature using the observed slopes of PL relations from the optical through the mid-infrared, and test the calibration by comparing the theoretical predictions with direct observations of the wavelength dependence of the scatter in the Large Magellanic Cloud Cepheid PL relation. In doing so we find the slope of the Period-Radius (PR) relation is c = 0.724 +/- 0.006. Investigating the effect of differential reddening suggests that this value may be overestimated by as much as 10%; however the same slope of the PR relation fits the (very much unreddened) Cepheids in IC1613, albeit with lower precision. The discussion given is ...

Madore, Barry F

2011-01-01

164

Intrinsic luminosities of the Jovian planets  

International Nuclear Information System (INIS)

We review available data and theories on the size and nature of interior power sources in the Jovian planets. Broad band infrared measurements indicate that Jupiter and Saturn have interior heat fluxes about 150 and 50 times larger, respectively, than the terrestrial value. While Neptune has a modest heat flux (approx.5 times terrestrial), it is clearly detected by earth-based measurements. Only Uranus seems to lack a detectable interior heat flow. Various models, ranging from simple cooling to gravitational layering to radioactivity, are discussed. Current evidence seems to favor a cooling model in which the escape of heat is regulated by the atmosphere. This model seems capable of explaining phenomena such as the uniformity of effective temperature over Jupiter's surface and the different emission rates of Uranus and Neptune. In such a model the heat radiated from the atmosphere may derived from depletion of a thermal reservoir in the interior, or it may derive from separation of chemical elements during formation of a core. Calculations indicate that in the earlier stages of cooling, Jupiter and Saturn may have more homogeneous abundances of hydrogen and helium and radiate energy derived from simple cooling. At a subsequent phase (which may be later than the present time), hydrogen and helium will separate and supply grativational energy. Either model is consistent with a hot, high-luminosity origin for the Jovian Planets

165

ATLAS gets its own luminosity detector  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

166

Intermediate-Luminosity Red Transients: SMARTS Monitoring  

Science.gov (United States)

A new class of intermediate-luminosity red transients (ILRTs) has been recognized recently, with maximum brightnesses between those of classical novae (CNe) and supernovae (SNe). During their outbursts, they evolve to extremely red colors, completely unlike CNe. A prototype is the Galactic star V838 Monocerotis, whose 2002 outburst illuminated a spectacular light echo, imaged by HST. Polarimetric imaging of the echo yielded a geometric distance of 6.2 kpc, making V838 Mon at maximum brighter than a CN. ILRTs have been discovered in several nearby galaxies, including M31 (1988), NGC 300 (2008 and 2010), and others. V838 Mon remained a luminous red supergiant throughout its outburst. Several years after eruption, its slowly expanding dusty photosphere ingested a B-type companion star, producing spectacular photometric and spectroscopic variability as the B star was engulfed. I organized a workshop on ILRTs, held at STScI in June 2011. A consensus emerged that there are two (at least) channels producing ILRTs: catastrophic mergers of contact binaries, and outbursts on massive stars of an uncertain nature, possibly electron-capture SNe. I propose to continue to monitor V838 Mon with the SMARTS 1.3m (photometry) and 1.5m (spectroscopy) telescopes. I also request TOO time on the same two telescopes to follow new ILRTs as they are discovered, which recently has been more than once a year.

Bond, Howard E.

2012-02-01

167

Higher luminosities via alternative incident channels  

Energy Technology Data Exchange (ETDEWEB)

We show that PEP provides some unique opportunities for one and two photon physics with real photons as well as for QCD studies with internal targets. Photon beams would avoid the major limitation on the luminosity of present machines and could provide PEP an ideal b-physics factory producing the full range of J/sub c//sup PC/ and J/sub b//sup PC/ states that may not be observable otherwise as well as allow a whole new class of ''missing-mass'' experiments. These latter particles are the pseudo-Goldstone bosons and their supersymmetric counterparts. These and related possibilities like a single-pass, ''free electron laser'' facility or even synchrotron radiation beam lines all favor a mini-maxi configuration for the low-beta insertions in PEP. This allows more diverse experiments without excluding any ongoing experimental programs. Such possibilities have interesting implications for a number of proposed facilities including the SSC. Some systematic machine physics studies over a range of energies are suggested. 24 refs., 6 figs.

Spencer, J.E.

1985-04-01

168

Higher luminosities via alternative incident channels  

International Nuclear Information System (INIS)

We show that PEP provides some unique opportunities for one and two photon physics with real photons as well as for QCD studies with internal targets. Photon beams would avoid the major limitation on the luminosity of present machines and could provide PEP an ideal b-physics factory producing the full range of J/sub c//sup PC/ and J/sub b//sup PC/ states that may not be observable otherwise as well as allow a whole new class of ''missing-mass'' experiments. These latter particles are the pseudo-Goldstone bosons and their supersymmetric counterparts. These and related possibilities like a single-pass, ''free electron laser'' facility or even synchrotron radiation beam lines all favor a mini-maxi configuration for the low-beta insertions in PEP. This allows more diverse experiments without excluding any ongoing experimental programs. Such possibilities have interesting implications for a number of proposed facilities including the SSC. Some systematic machine physics studies over a range of energies are suggested. 24 refs., 6 figs

169

Isotropic Luminosity Indicators in a Complete AGN Sample  

Science.gov (United States)

The [O IV] ?25.89 ?m line has been shown to be an accurate indicator of active galactic nucleus (AGN) intrinsic luminosity in that it correlates well with hard (10-200 keV) X-ray emission. We present measurements of [O IV] for 89 Seyfert galaxies from the unbiased revised Shapley-Ames (RSA) sample. The [O IV] luminosity distributions of obscured and unobscured Seyferts are indistinguishable, indicating that their intrinsic AGN luminosities are quite similar and that the RSA sample is well suited for tests of the unified model. In addition, we analyze several commonly used proxies for AGN luminosity, including [O III] ?5007 Å, 6 cm radio, and 2-10 keV X-ray emission. We find that the radio luminosity distributions of obscured and unobscured AGNs show no significant difference, indicating that radio luminosity is a useful isotropic luminosity indicator. However, the observed [O III] and 2-10 keV luminosities are systematically smaller for obscured Seyferts, indicating that they are not emitted isotropically.

Diamond-Stanic, Aleksandar M.; Rieke, George H.; Rigby, Jane R.

2009-06-01

170

ISOTROPIC LUMINOSITY INDICATORS IN A COMPLETE AGN SAMPLE  

International Nuclear Information System (INIS)

The [O IV] ?25.89 ?m line has been shown to be an accurate indicator of active galactic nucleus (AGN) intrinsic luminosity in that it correlates well with hard (10-200 keV) X-ray emission. We present measurements of [O IV] for 89 Seyfert galaxies from the unbiased revised Shapley-Ames (RSA) sample. The [O IV] luminosity distributions of obscured and unobscured Seyferts are indistinguishable, indicating that their intrinsic AGN luminosities are quite similar and that the RSA sample is well suited for tests of the unified model. In addition, we analyze several commonly used proxies for AGN luminosity, including [O III] ?5007 A, 6 cm radio, and 2-10 keV X-ray emission. We find that the radio luminosity distributions of obscured and unobscured AGNs show no significant difference, indicating that radio luminosity is a useful isotropic luminosity indicator. However, the observed [O III] and 2-10 keV luminosities are systematically smaller for obscured Seyferts, indicating that they are not emitted isotropically.

171

Monitoring the relative instantaneous luminosity with detector multiplicities  

CERN Document Server

The use of detector multiplicities is presented as a method to monitor relative instantaneous luminosity at LHCb. The proportionality between multiplicity and the instantaneous luminosity is studied for two sub-detectors: the SPD and the PileUp System. The sensitivity that can be obtained as a function of the number of events used for monitoring is also discussed.

Calvo, M

2009-01-01

172

The Radio and Gamma-Ray Luminosities of Blazars  

CERN Document Server

Based on the $\\gamma$-ray data of blazars in the third EGRET catalog and radio data at 5 GHz, we studied the correlation between the radio and $\\gamma$-ray luminosities using two statistical methods. The first method was the partial correlation analysis method, which indicates that there exist correlations between the radio and $\\gamma$-ray luminosities in both high and low states as well as in the average case. The second method involved a comparison of expected $\\gamma$-ray luminosity distribution with the observed data using the Kolmogorov-- Smirnov (KS) test. In the second method, we assumed that there is a correlation between the radio and $\\gamma$-ray luminosities and that the $\\gamma$-ray luminosity function is proportional to the radio luminosity function. The KS test indicates that the expected gamma-ray luminosity distributions are consistent with the observed data in a reasonable parameter range. Finally, we used different $\\gamma$-ray luminosity functions to estimate the possible 'observed' $\\gamm...

Zhang, L; Fan, J H

2001-01-01

173

PHYSICS AT HIGH LUMINOSITY MUON COLLIDERS AND A FACILITY OVERVIEW.  

Energy Technology Data Exchange (ETDEWEB)

Physics potentials at future colliders including high luminosity {mu}{sup +}{mu}{sup -} colliders are discussed. Luminosity requirement, estimates for Muon collider energies of interest (0.1 TeV to 100 TeV) are calculated. Schematics and an overview of Muon Collider facility concept are also included.

PARSA,Z.

2001-07-01

174

Near-Infrared Properties of Moderate-Redshift Galaxy Clusters: Luminosity Functions and Density Profiles  

Energy Technology Data Exchange (ETDEWEB)

We present K-band imaging for 15 of the Canadian Network for Observational Cosmology (CNOC1) clusters. The extensive spectroscopic dataset available for these clusters allows us to determine the cluster K-band luminosity function and density profile without the need for statistical background subtraction. The luminosity density and number density profiles can be described by NFW models with concentration parameters of c{sub l} = 4.28 {+-} 0.70 and c{sub g} = 4.13 {+-} 0.57 respectively. Comparing these to the dynamical mass analysis of the same clusters shows that the galaxy luminosity and number density profiles are similar to the dark matter profile, and are not less concentrated like in local clusters. The luminosity functions show that the evolution of K. over the redshift range 0.2 < z < 0.5 is consistent with a scenario where the majority of stars in cluster galaxies form at high-redshift (z{sub f} > 1.5) and evolve passively thereafter. The best-fit for the faint-end slope of the luminosity function is {alpha} = -0.84 {+-} 0.08, which indicates that it does not evolve between z = 0 and z = 0.3. Using Principal Component Analysis of the spectra we classify cluster galaxies as either star-forming/recently-star-forming (EM+BAL) or non-star forming (ELL) and compute their respective luminosity functions. The faint-end slope of the ELL luminosity function is much shallower than for the EM+BAL galaxies at z = 0.3, and suggests the number of faint ELL galaxies in clusters decreases by a factor of {approx} 3 from z = 0 to z = 0.3. The redshift evolution of K* for both EM+BAL and ELL types is consistent with a passively evolving stellar population formed at high-redshift. Passive evolution in both classes, as well as the total cluster luminosity function, demonstrates that the bulk of the stellar population in all bright cluster galaxies is formed at high-redshift and subsequent transformations in morphology/color/spectral-type have little effect on the total stellar mass.

Muzzin, Adam; Yee, H.K.C.; /Toronto U., Astron. Dept.; Hall, Patrick B.; /York U., Canada; Ellingson, E.; /Colorado U., CASA; Lin, Huan; /Fermilab

2006-12-01

175

The energy source of intermediate luminosity optical transients  

CERN Document Server

We argue that transient systems with luminosity between novae and supernovae (SNe) are powered by gravitational energy of mass accreted onto, or a companion merges with, a main-sequence star. These transient events are termed Intermediate-Luminosity Optical Transients (ILOTs; other terms in use are Intermediate-Luminosity Red Transients and Red Novae). We show that despite the wide range of 10^{45}-10^{50} erg, the typical energy released by ILOTs can be expressed as a function of fundamental variables: the planck constant, speed of light, gravitational constant, electron mass, neutron mass, and ignition temperature of hydrogen. This expression explains why ILOTs are located between SNe and novae with respect to their total energy. We also put an upper limit on the power (luminosity) of ILOTs, which explains their lower luminosity than SNe.

Soker, Noam

2011-01-01

176

Luminosity for electron-positron collision in TRISTAN  

International Nuclear Information System (INIS)

Preliminary considerations on the luminosity for electron-positron collision in the TRISTAN electron ring are presented. It is shown that luminosity of 1032 cm-2s-1 can be achieved at 15 GeV with a beam current of 100 mA (each beam) and an RF power of 3.2 -- 4.1 MW (each beam). In the lower energy region, the luminosity is tune-shift limited and decreases as E2. In the higher energy region, the luminosity is RF power limited and decreases as 1/E3 or faster. The energy region above 5 GeV can be used for physics experiments with a luminosity over 1031 cm-2s-1. The maximum operating energy should be determined by the detailed investigation on the properties of the RF system. (auth.)

177

The Luminosities of the Coldest Brown Dwarfs  

Science.gov (United States)

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. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

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

2014-11-01

178

The white dwarf luminosity function - I. Statistical errors and alternatives  

Science.gov (United States)

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 method is usually employed in computing the white dwarf luminosity function and other methods have not been applied so far to the observational sample of spectroscopically identified white dwarfs - in sharp contrast with the situation when galaxy luminosity functions are derived from a large variety of samples. Moreover, the statistical significance of the white dwarf luminosity function has also received little attention and a thorough study still remains to be done. In this paper, we study, using a controlled synthetic sample of white dwarfs generated using a Monte Carlo simulator, which is the statistical significance of the white dwarf luminosity function and which are the expected biases. We also present a comparison between different estimators for computing the white dwarf luminosity function. We find that for sample sizes large enough the method provides a reliable characterization of the white dwarf luminosity function, provided that the input sample is selected carefully. Particularly, the method recovers well the position of the cut-off of the white dwarf luminosity function. However, this method turns out to be less robust than the Choloniewski method when the possible incompletenesses of the sample are taken into account. We also find that the Choloniewski method performs better than the method in estimating the overall density of white dwarfs, but misses the exact location of the cut-off of the white dwarf luminosity function.

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

2006-07-01

179

TRUNCATION OF THE INNER ACCRETION DISK AROUND A BLACK HOLE AT LOW LUMINOSITY  

International Nuclear Information System (INIS)

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 in) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that R in is very close to the black hole at high and moderate luminosities (?>1% of the Eddington luminosity, L 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 Edd and show that R in increases by a factor of >27 over the value found when GX 339 - 4 was bright. The exact value of R in depends on the inclination of the inner disk (i), and we derive 90% confidence limits of R in > 35Rg at i = 00 and R in > 175Rg at i = 300. 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.

180

Keck Deep Fields. II. The UV Galaxy Luminosity Function at z~4, 3, and 2  

CERN Document Server

We use very deep UGRI multi-field imaging obtained at the Keck telescope to study the evolution of the rest-frame 1700A galaxy luminosity function as the Universe doubles its age from z~4 to z~2. The depth of our imaging allows us to constrain the faint end of the luminosity function reaching M_1700A ~ -18.5 at z~3 (equivalent to ~1M_sun/yr) accounting for both N^1/2 uncertainty in the number of galaxies and for cosmic variance. We carefully examine many potential sources of systematic bias in our LF measurements before drawing the following conclusions. We find that the luminosity function of Lyman Break Galaxies evolves with time and that this evolution is likely differential with luminosity. The result is best constrained between the epochs at z~4 and z~3, where we find that the number density of sub-L* galaxies increases with time by at least a factor of 2.3 (11sigma statistical confidence); while the faint end of the LF evolves, the bright end appears to remain virtually unchanged, indicating that there ...

Thompson, M S D

2005-01-01

 
 
 
 
181

The Metallicity-Luminosity Relation, Effective Yields, and Metal Loss in Spiral and Irregular Galaxies  

CERN Document Server

I present results on the correlation between galaxy mass, luminosity, and metallicity for a sample of spiral and irregular galaxies having well-measured abundance profiles, distances, and rotation speeds. Additional data for low surface brightness galaxies from the literature are also included for comparison. These data are combined to study the metallicity-luminosity and metallicity-rotation speed correlations for spiral and irregular galaxies. The metallicity luminosity correlation shows its familiar form for these galaxies, a roughly uniform change in the average present-day O/H abundance of about a factor 100 over 11 magnitudes in B luminosity. However, the O/H - V(rot) relation shows a change in slope at a rotation speed of about 125 km/sec. At faster V(rot), there appears to be no relation between average metallicity and rotation speed. At lower V(rot), the metallicity correlates with rotation speed. This change in behavior could be the result of increasing loss of metals from the smaller galaxies in su...

Garnett, D R

2002-01-01

182

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

Science.gov (United States)

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.

Ates, Ozgur

183

How sensitive are predicted galaxy luminosities to the choice of stellar population synthesis model?  

Science.gov (United States)

We present a new release of the GALFORM semi-analytical model of galaxy formation and evolution, which exploits a Millennium Simulation-class N-body run performed with the Wilkinson Microwave Anisotropy Probe 7 cosmology. We use this new model to study the impact of the choice of stellar population synthesis (SPS) model on the predicted evolution of the galaxy luminosity function. The semi-analytical model is run using seven different SPS models. In each case, we obtain the rest-frame luminosity function in the far-ultraviolet, optical and near-infrared (NIR) wavelength ranges. We find that both the predicted rest-frame ultraviolet and optical luminosity function are insensitive to the choice of SPS model. However, we find that the predicted evolution of the rest-frame NIR luminosity function depends strongly on the treatment of the thermally pulsating asymptotic giant branch (TP-AGB) stellar phase in the SPS models, with differences larger than a factor of 2 for model galaxies brighter than MAB(K) - 5 log h < -22 (˜L* for 0 ? z ? 1.5). We have also explored the predicted number counts of galaxies, finding remarkable agreement between the results with different choices of SPS model, except when selecting galaxies with very red optical-NIR colours. The predicted number counts of these extremely red galaxies appear to be more affected by the treatment of star formation in discs than by the treatment of TP-AGB stars in the SPS models.

Gonzalez-Perez, V.; Lacey, C. G.; Baugh, C. M.; Lagos, C. D. P.; Helly, J.; Campbell, D. J. R.; Mitchell, P. D.

2014-03-01

184

The X-ray luminosity function of AGN at z~3  

CERN Document Server

We combine Lyman-break colour selection with ultradeep (> 200 ks) Chandra X-ray imaging over a survey area of ~0.35 deg^2 to select high redshift AGN. Applying careful corrections for both the optical and X-ray selection functions, the data allow us to make the most accurate determination to date of the faint end of the X-ray luminosity function (XLF) at z~3. Our methodology recovers a number density of X-ray sources at this redshift which is at least as high as previous surveys, demonstrating that it is an effective way of selecting high z AGN. Comparing to results at z=1, we find no evidence that the faint slope of the XLF flattens at high z, but we do find significant (factor ~3.6) negative evolution of the space density of low luminosity AGN. Combining with bright end data from very wide surveys we also see marginal evidence for continued positive evolution of the characteristic break luminosity L*. Our data therefore support models of luminosity-dependent density evolution between z=1 and z=3. A sharp up...

Aird, James; Georgakakis, Antonis; Laird, Elise S; Steidel, Charles C; Sharon, Chelsea

2008-01-01

185

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

186

GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES  

Energy Technology Data Exchange (ETDEWEB)

Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic bulge scans with RXTE's Proportional Counter Array instrument. Strong luminosity variations are common (and well documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster (GC) X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in GCs. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few Multiplication-Sign 10{sup 36} erg s{sup -1} in both old field populations and GCs.

Cartwright, T. F.; Engel, M. C.; Heinke, C. O.; Sivakoff, G. R.; Berger, J. J.; Gladstone, J. C.; Ivanova, N., E-mail: heinke@ualberta.ca [Physics Department, 4-183 CCIS, University of Alberta, Edmonton, AB T6G 2E1 (Canada)

2013-05-10

187

TOWARD TIGHT GAMMA-RAY BURST LUMINOSITY RELATIONS  

International Nuclear Information System (INIS)

The large scatters of luminosity relations of gamma-ray bursts (GRBs) have been one of the most important reasons preventing the extensive application of GRBs in cosmology. Many efforts have been made to seek tight luminosity relations. With the latest sample of 116 GRBs with measured redshift and spectral parameters, we investigate 6 two-dimensional (2D) correlations and 14 derived three-dimensional (3D) correlations of GRBs to explore the possibility of decreasing the intrinsic scatters of the luminosity relations of GRBs. We find the 3D correlation of Epeak-?RT-L to be evidently tighter (at the 2? confidence level) than its corresponding 2D correlations, i.e., the Epeak-L and ?RT-L correlations. In addition, the coefficients before the logarithms of Epeak and ?RT in the Epeak-?RT-L correlation are almost exact opposites of each other. Inputting this situation as a prior reduces the relation to L?(E'peak/?RT')0.842±0.064, where E'peak and ?'RT denote the peak energy and minimum rise time in the GRB rest frame. We discuss how our findings can be interpreted/understood in the framework of the definition of the luminosity (energy released in units of time). Our argument about the connection between the luminosity relations of GRBs and the definition of the luminosity provides a clear direction for exploring tighter luminosity relations of GRBs in the future.

188

GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES  

International Nuclear Information System (INIS)

Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic bulge scans with RXTE's Proportional Counter Array instrument. Strong luminosity variations are common (and well documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster (GC) X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in GCs. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few × 1036 erg s–1 in both old field populations and GCs.

189

The spectrometer system for measuring ZEUS luminosity at HERA  

International Nuclear Information System (INIS)

The upgrade of the HERA accelerator has provided much increased collider luminosity. In turn, the improvements have necessitated a new design for the ZEUS luminosity measurements. The intense synchrotron radiation field, as well as the high probability of a bremsstrahlung photon in each bunch crossing, posed new experimental constraints. In this report, we describe how these challenges were met with the ZEUS luminosity spectrometer system. The design, testing and commissioning of the device are described, and the results from the initial operational experience are reported. (orig.)

190

Nearby debris disk systems with high fractional luminosity reconsidered  

CERN Document Server

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.

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

2006-01-01

191

Precision luminosity measurement at LHCb with beam-gas imaging  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Barschel, Colin

2014-01-01

192

Peak luminosity correlated low-frequency oscillations in black holes  

Science.gov (United States)

Based on Rossi X-ray Timing Explorer (RXTE) observational data, we study the timing and spectral properties of some peculiar low-frequency (LF) quasi-periodic oscillations (QPOs), which have been found at the peak luminosity of the outburst of some transient black hole (BH) binaries: the 2005 outburst of GRO J1655-40, the 2003 outburst of H1743-322 and the 1998 outburst of XTE J1550-564. Appearing in the ultraluminous state, these QPOs from different sources show some common properties. The amplitude is very weak (less than 1 per cent) and the quality factor is larger than 6. Moreover, these QPOs (about several Hz) sometimes show up simultaneously with another QPO (about 10 Hz), but their frequencies are not harmonically related. We also find that the frequencies of these QPOs are inversely correlated with the mass of the BH, which implies that these QPOs might be correlated with the innermost stable circular orbit. The QPO frequency is also negative correlated with the inner disc radius among BHs. However, its frequency is too low to ascribe it to the Keperlian orbit frequency. Moreover, we discuss the physical origin of these QPOs and we suggest that they are not produced by the viscous variability of the inner disc either.

Li, Z. B.; Gao, H. Q.; Zhang, Z.; Zhang, S.; Qu, J. L.; Zhang, C. M.; Song, L. M.

2014-05-01

193

Evolution of Galaxy Luminosity Function Using Photometric Redshifts  

CERN Document Server

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...

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

194

STAR FORMATION RATES FOR STARBURST GALAXIES FROM ULTRAVIOLET, INFRARED, AND RADIO LUMINOSITIES  

International Nuclear Information System (INIS)

We present a comparison of star formation rates (SFR) determined from mid-infrared 7.7 ?m polycyclic aromatic hydrocarbon (PAH) luminosity [SFR(PAH)], from 1.4 GHz radio luminosity [SFR(radio)], and from far-ultraviolet luminosity [SFR(UV)] for a sample of 287 starburst galaxies with z ?(7.7 ?m)] - 42.57 ± 0.2, for SFR in Msun yr-1 and ?L ?(7.7 ?m) the luminosity at the peak of the 7.7 ?m PAH feature in erg s-1, is found to agree with SFR(radio). Comparing with SFR(UV) determined independently from ultraviolet observations of the same sources with the Galaxy Evolution Explorer mission (not corrected for dust extinction), the median log [SFR(PAH)/SFR(UV)] = 1.67, indicating that only 2% of the ultraviolet continuum typically escapes extinction by dust within a starburst. This ratio SFR(PAH)/SFR(UV) depends on infrared luminosity, with the form log [SFR(PAH)/SFR(UV)] = (0.53 ± 0.05)log [?L?(7.7 ?m)] - 21.5 ± 0.18, indicating that more luminous starbursts are also dustier. Using our adopted relation between ?L?(7.7 ?m) and L ir, this becomes log [SFR(PAH)/SFR(UV)]= (0.53 ± 0.05)log Lir - 4.11 ± 0.18, for Lir in Lsun. Only blue compact dwarf galaxies show comparable or greater SFR(UV) compared to SFR(PAH). We also find that the ratio SFR(PAH)/SFR(UV) is similar to that in infrared-selected starbursts for a sample of Markarian starburst galaxies originally selected using optical classification, which implies that there is no significant selection effect in SFR(PAH)/SFR(UV) using starburst galaxies discovered by Spitzer. These results indicate that SFRs determined with ultraviolet luminosities require dust corrections by a factor of ?10 for typical local starbursts but this factor increases to >700 for the most luminous starbursts at z ? 2.5. Application of this factor explains why the most luminous starbursts discovered by Spitzer at z ? 2.5 are optically faint; with this amount of extinction, the optical magnitude of a starburst having f?(7.7 ?m) of 1 mJy should be V? 25.6.

195

The development of CVD diamond tracking detectors for high luminosity experiments at the LHC  

International Nuclear Information System (INIS)

Data from the May 1995 test beam runs at CERN have been analysed to measure the signal-to-noise ratio, spatial resolution and charge collection distance of a CVD diamond tracking detector with a pitch of 50 ?m. The signal-to-noise ratio for the diamond detector was measured to be in the range 8:1 (using the most probable signal) to 12:1 (using the mean). The detector had a corresponding spatial resolution of ? = 12.9 ?m. The effect of irradiating, or 'pumping', the detector with a 90Sr source for a prolonged period (44 hours) was also studied. The pumping effects were measured by comparing distributions before and after irradiation. The spatial resolution was measured to be ? = 10.4 ?m before pumping and ? = 12.9 ?m after pumping; a decrease of ? 24% is observed. The charge collection distance was measured to be 49 ?m before pumping and 85 ?m after pumping; a factor of 1.7 higher. From the 1995 data runs, elastic Compton scattering at HERA, e+p ? e+p?, has been used to obtain a measurement of integrated luminosity. The 1994 luminosity was measured to be 2.88 ± 0.09(stat) -0.11(syst)+0.14(syst) pb-1 and the 1995 luminosity to be 6.35 ± 0.14(stat) -0.20(syst)+0.34(syst) pb-1. The corresponding luminosity values obtained using the luminosity monitor are 2.988 ± 0.045 pb-1 and 6.362 ± 0.095 pb-1 respectively, and are in good agreement with the results obtained from Compton Scattering. Elastic Compton scattering has also been used for a measurement of the photon density of the proton. The results can be interpreted as the fraction of the proton's momentum carried by the electromagnetic field which surrounds the proton. Data and theory compare favourably. (author)

196

Collider physics at high energies and low luminosities  

Science.gov (United States)

While very high acceleration gradients are expected in novel accelerating schemes such as those discussed by IZEST, generating high luminosities will be extremely challenging and will likely require a separate technology revolution. It is important to determine if a low-luminosity but high energy collider would have serious interest from a particle physics perspective. We consider a process involving physics beyond the Standard Model that would be detectable at high energies without requiring the types of luminosities normally quoted for future colliders, "classicalization". In this example, scattering cross sections grow with a power of the center-of-mass energy, thereby reducing the luminosity requirement at high energies. Another process discussed is deep-inelastic-scattering of electrons on protons, where a precision measurement of the energy dependence of the scattering cross section could yield information about physics processes at much higher scales.

Caldwell, A.

2014-05-01

197

Implementation and experience with luminosity levelling with offset beam  

CERN Document Server

The practice of luminosity levelling with an offset beam has been used as a routine operation in the LHC since 2011. This paper will describe how it has been implemented and what has been the operational experience with the system.

Follin, F

2014-01-01

198

The Intrinsic Quasar Luminosity Function: Accounting for Accretion Disk Anisotropy  

CERN Document Server

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...

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

2014-01-01

199

The relation between bar formation, galaxy luminosity, and environment  

CERN Document Server

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...

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

2013-01-01

200

Measurement of the absolute luminosity with the ALEPH detector  

Energy Technology Data Exchange (ETDEWEB)

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.).

Decamp, D.; Deschizeaux, B.; Goy, C.; Lees, J.P.; Minard, M.N. (CNRS, 74 - Annecy-le-Vieux (France). Lab. de Physique des Particules); Alemany, R.; Crespo, J.M.; Delfino, M.; Fernandez, E.; Gaitan, V.; Garrido, Ll.; Mir, Ll.M.; Pacheco, A. (Universidad Autonoma de Barcelona (Spain). Lab. de Fisica de Altas Energias); Catanesi, M.G.; Creanza, D.; De Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Maggi, M.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G. (INFN, Bari (Italy) Bari Univ. (Italy). Dipt. di Fisica); Gao, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Lou, J.; Qiao, C.; Ruan, T.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhao, W. (Academia Sinica, Beijing, BJ (China). Inst. of High-Energy Physics); Atwood, W.B.; Bauerdick, L.A.T.; Bird, F.; Blucher, E.; Bonvicini, G.; Bossi, F.; Boudreau, J.; Brown, D.; Burnett, T.H.; Drevermann, H.; Forty, R.W.; Grab, C.; Hagelberg, R.; Haywood,; ALEPH Collaboration

1992-02-01

 
 
 
 
201

Performance of the Muon MWPC in high luminosity runs  

CERN Document Server

The LHCb detector was conceived to operate with an average luminosity of 2x10$^{32}$cm$^{-1}$s$^{-1}$. During the last year of the LHC run, the whole apparatus has shown to be able to perfectly acquire and manage data produced at a luminosity as high as 4x10$^{32}$cm$^{-2}$s$^{-1}$. In this condition, all subdetectors operated at average particle rates higher than the design ones and in particular the detectors equipping the Muon System had to sustain a particle rate as high as 100kHz/cm$^2$. In order to study the possibility of increasing the luminosity of operation several tests were performed. This paper reports detailed studies on the performance of the LHCb Muon System in runs with a luminosity between 4 x 10$^{32}$cm$^{-2}$s$^{-1}$ and 10$^{33}$ cm$^{-2}$s$^{-1}$.

Pinci, Davide

2013-01-01

202

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.)

203

Environmental and morphological dependence of the luminosity function of galaxies  

Science.gov (United States)

In this paper we analyze the environmental and morphological dependence of the galaxy luminosity function (LF) by using a sample of homogeneous observational data: the Updated Zwicky Catalog (UZC). This sample is used to study the type-specific luminosity function of galaxies in the local field as well as in various environments which cover from isolated galaxies to moderately rich clusters. We show that the overall LF cannot always be explained as a composition, taking into account the relative abundance of Hubble types, of type-dependent luminosity functions (LFT) with universal shapes. The environment, characterized by its richness r, also plays a crucial role in the shape of the specific LF for each Hubble type T. Nevertheless, the r and T dependence appears to be weak enough to allow for the definition of nearly universal luminosity functions, Phi (r,T) with coarse-grained bins on both r and T.

Cuesta-Bolao, M. J.; Serna, A.

2003-07-01

204

Layered convection as the origin of Saturn's luminosity anomaly  

CERN Document Server

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...

Leconte, Jérémy

2013-01-01

205

A two-mode planetary nebula luminosity function  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a new Planetary Nebula Luminosity Function (PNLF) that includes two populations in the distribution. Our PNLF is a direct extension of the canonical function proposed by Jacoby et al. (1987), in order to avoid problems related with the histogram construction, it is cast in terms of cumulative functions. We are interested in recovering the shape of the faint part of the PNLF in a consistent manner, for galaxies with and without a dip in their PN luminosity function...

Rodri?guez-gonza?lez, A.; Herna?ndez-marti?nez, L.; Esquivel, A.; Raga, A. C.; Stasin?ska, G.; Pen?a, M.; Mayya, D.

2014-01-01

206

Experience with high luminosity running at the CERN ISR  

International Nuclear Information System (INIS)

Discussed is the experience of the CCOR and COR collaborations at the ISR at the steel low ? intersection region, with luminosities up to 6 x 1031 cm-2s-1. In general, this luminosity level has caused only minor inconvenience for a detector covering polar angles 45 to 135 degrees in the center of mass, except for a special unrestrictive trigger on total transverse energy

207

On the Luminosity Distance and the Hubble Constant  

Directory of Open Access Journals (Sweden)

Full Text Available By differentiating luminosity distance with respect to time using its standard formula we ?nd that the peculiar velocity is a time varying velocity of light. Therefore, a new de?nition of the luminosity distance is provided such that the peculiar velocity is equal to c. Using this de?nition a Hubble constant H0 = 67.3 km s?1 Mpc?1 is obtained from supernovae data.

Yuri Heymann

2013-07-01

208

The luminosity function of Swift long gamma-ray bursts  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The accumulation of {\\it Swift} observed gamma-ray bursts (GRBs) gradually makes it possible to directly derive a GRB luminosity function (LF) from observational luminosity distribution, where however two complexities must be involved as (i) the evolving connection between GRB rate and cosmic star formation rate and (ii) observational selection effects due to telescope thresholds and redshift measurements. With a phenomenological investigation on these two complexities, we c...

Cheng, Ks; Zheng, Xp; Cao, Xf; Yu, Yw

2011-01-01

209

The rate and luminosity function of Short GRBs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Piran, Tsvi; Guetta, Dafne

2006-01-01

210

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.)

211

Triggering at high luminosity: fake triggers from pile-up  

International Nuclear Information System (INIS)

Triggers based on a cut in transverse momentum (p/sub t/) have proved to be useful in high energy physics both because they indicte that a hard constituent scattering has occurred and because they can be made quickly enough to gate electronics. These triggers will continue to be useful at high luminosities if overlapping events do not cause an excessive number of fake triggers. In this paper, I determine if this is indeed a problem at high luminosity machines

212

Luminosity and Beam-spot Determination Using the ATLAS Detector  

International Nuclear Information System (INIS)

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 ?s = 900 GeV (in 2009) and ?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 diffractive components of the cross section. Smaller systematic uncertainties are obtained using an absolute calibration of the luminosity via beam separation scans. The spatial distribution of pp interactions is first reconstructed in real time by a dedicated algorithm in the high-level trigger and later more precisely by an offline reconstruction algorithm. The latter takes full advantage of the high tracking efficiency and resolution of the Inner Detector through an un-binned maximum likelihood fit to reconstructed vertices of candidate primary interactions. This fit determines all relevant parameters of the LHC luminous region at the ATLAS interaction point, including the resolution-corrected size of the beam spot. Using beam separation scans, the length scales of the beam-position monitors are calibrated against the displacement of the luminous centroid measured during these scans. This significantly improves the absolute accuracy of the luminosity calibration obtained via beam scans. The rate of reconstructed primary vertex candidates provides a relative measurement of the luminosity. (author)

213

Luminosity function and jet structure of Gamma Ray Bursts  

CERN Document Server

The structure of Gamma Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could instead be structured, namely with energy and velocity that depend on the angular distance from the axis of the jet. We try to get some insight about the still unknown structure of GRBs by studying their luminosity function. We show that low (1e46-1e48 erg/s) and high (i.e. with L > 1e50 erg/s) luminosity GRBs can be described by a unique luminosity function, which is also consistent with current lower limits in the intermediate luminosity range (1e48-1e50} erg/s). We derive analytical expressions for the luminosity function of GRBs in uniform and structured jet models and compare them with the data. Uniform jets can reproduce the entire luminosity function with reasonable values of the free parameters. A structured jet can also fit adequately the current data, provided that the energy within the ...

Pescalli, A; Salafia, O S; Ghisellini, G; Nappo, F; Salvaterra, R

2014-01-01

214

Low Luminosity Radio Loud Active Galactic Nuclei  

CERN Document Server

I review observational properties of low power radio loud AGN. High resolution VLBI observations allow the estimate of the jet velocity and orientation with respect to the line of sight and the determination of the Doppler factor. These data reveal rich structures, including two-sided jets and secondary components. New results on 1144+35, a giant radio source with superluminal motion are shown in detail.

Giovannini, G

2007-01-01

215

MID-IR LUMINOSITIES AND UV/OPTICAL STAR FORMATION RATES AT z < 1.4  

International Nuclear Information System (INIS)

Ultraviolet (UV) nonionizing continuum and mid-infrared (IR) emission constitute the basis of two widely used star formation (SF) indicators at intermediate and high redshifts. We study 2430 galaxies with z 10-1012 Lsun). We show that the IR luminosity can be estimated from the UV and optical photometry to within a factor of 2, implying that most z IR>1011 Lsun, yet with little current SF. For them a reasonable amount of dust absorption of stellar light (but presumably higher than in nearby early-type galaxies) is sufficient to produce the observed levels of IR, which includes a large contribution from intermediate and old stellar populations. In our sample, which contains very few ultraluminous IR galaxies, optical and X-ray active galactic nuclei do not contribute on average more than ?50% to the mid-IR luminosity, and we see no evidence for a large population of 'IR excess' galaxies.

216

Restriction on the energy and luminosity of e(+)e(-) storage rings due to beamstrahlung.  

Science.gov (United States)

The role of beamstrahlung in high-energy e(+)e(-) storage-ring colliders (SRCs) is examined. Particle loss due to the emission of single energetic beamstrahlung photons is shown to impose a fundamental limit on SRC luminosities at energies 2E(0)?140??GeV for head-on collisions and 2E(0)?40??GeV for crab-waist collisions. With beamstrahlung taken into account, we explore the viability of SRCs in the 2E(0)=240-500???GeV range, which is of interest in the precision study of the Higgs boson. At 2E(0)=240??GeV, SRCs are found to be competitive with linear colliders; however, at 2E(0)=400-500??GeV, the attainable SRC luminosity would be a factor 15-25 smaller than desired. PMID:25166545

Telnov, V I

2013-03-15

217

The Radius-Luminosity Relationship for Active Galactic Nuclei : The Effect of Host-Galaxy Starlight on Luminosity Measurements  

DEFF Research Database (Denmark)

We have obtained high resolution images of the central regions of 14 reverberation-mapped active galactic nuclei (AGN) using the Hubble Space Telescope Advanced Camera for Surveys High Resolution Camera to account for host-galaxy starlight contamination of measured AGN luminosities. We measure the host-galaxy starlight contribution to the continuum luminosity at 5100 A through the typical ground-based slit position and geometry used in the reverberation-mapping campaigns. We find that removing the starlight contribution results in a significant correction to the luminosity of each AGN, both for lower luminosity sources, as expected, but also for the higher luminosity sources such as the PG quasars. After accounting for the host galaxy starlight, we revisit the well-known broad-line region radius--luminosity relationship for nearby AGN. We find the power-law slope of the relationship for the H beta line to be 0.518 +/- 0.039, shallower than previously reported and consistent with the slope of 0.5 expected fromthe naive theoretical assumption that all AGN have, on average, the same ionizing spectrum and the same ionization parameter and gas density in the H beta line-emitting region.

Bentz, Misty C.; Peterson, Bradley M.

2006-01-01

218

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

219

On the Radio and Optical Luminosity Evolution of Quasars  

Energy Technology Data Exchange (ETDEWEB)

We calculate simultaneously the radio and optical luminosity evolutions of quasars, and the distribution in radio loudness R defined as the ratio of radio and optical luminosities, using a flux limited data set containing 636 quasars with radio and optical fluxes from White et al. We first note that when dealing with multivariate data it is imperative to first determine the true correlations among the variables, not those introduced by the observational selection effects, before obtaining the individual distributions of the variables. We use the methods developed by Efron and Petrosian which are designed to obtain unbiased correlations, distributions, and evolution with redshift from a data set truncated due to observational biases. It is found that as expected the population of quasars exhibits strong positive correlation between the radio and optical luminosities and that this correlation deviates from a simple linear relation in a way indicating that more luminous quasars are more radio loud. We also find that there is a strong luminosity evolution with redshift in both wavebands, with significantly higher radio than optical evolution. We conclude that the luminosity evolution obtained by arbitrarily separating the sources into radio loud (R > 10) and radio quiet (R < 10) populations introduces significant biases that skew the result considerably. We also construct the local radio and optical luminosity functions and the density evolution. Finally, we consider the distribution of the radio loudness parameter R obtained from careful treatment of the selection effects and luminosity evolutions with that obtained from the raw data without such considerations. We find a significant difference between the two distributions and no clear sign of bi-modality in the true distribution. Our results indicate therefore, somewhat surprisingly, that there is no critical switch in the efficiency of the production of disk outflows/jets between very radio quiet and very radio loud quasars, but rather a smooth transition. Also, this efficiency seems higher for the high-redshift and more luminous sources in the considered sample.

Singal, J.; /KIPAC, Menlo Park /SLAC; Petrosian, V.; /KIPAC, Menlo Park /SLAC /Stanford U., Phys. Dept. /Stanford U., Appl. Phys. Dept.; Lawrence, A.; /Edinburgh U., Inst. Astron.; Stawarz, L.; /JAXA, Sagamihara /Jagiellonian U., Astron. Observ.

2011-05-20

220

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.)

 
 
 
 
221

A luminosity measurement at LEP using the L3 detector  

Energy Technology Data Exchange (ETDEWEB)

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.).

Koffeman, E.N.

1996-06-25

222

EVOLUTION OF GALAXY LUMINOSITY FUNCTION USING PHOTOMETRIC REDSHIFTS  

International Nuclear Information System (INIS)

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 the LFs obtained using photometric redshifts from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ?4800 galaxies. We find that for z ? 2.0, 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 the CFHTLS comprising ?386,000 galaxies to compute the LF of the combined fields and directly estimate the error in the parameters based on the field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ?0.7 mag from z ? 1.8 to z ? 0.3, while the characteristic density ?* increases by a factor of ?4 in the same redshift interval. We use the galaxy classification provided by the template fitting program used to compute photometric redshifts and split the sample into galaxy types. We find that these Schechter parameters evolve differently for each galaxy type, an indication that their evolution is a combination of several effects: galaxy merging, star formation quenching, and mass assembly. All these results are compatible with those obtained by different spectroscopic surveys such as VVDS, DEEP2, and zCosmos, which reinforces the fact that photometric redshifts can be used to study galaxy evolution, at least for the redshift bins adopted so far. This is of great interest since future very large imaging surveys containing hundreds of millions of galaxies will allow us to obtain important precise measurements to constrain the evolution of the LF and to explore the dependence of this evolution on morphology and/or color helping constrain the mechanisms of galaxy evolution.

223

The critical accretion luminosity for magnetized neutron stars  

CERN Document Server

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...

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

2014-01-01

224

Performance evaluation and optimization of the luminosity detector ALFA  

CERN Document Server

The startup of the LHC (Large Hadron Collider) has initialized a new era in particle physics. The standard model of particle physics has for the last 40 years with tremendous success described all measurements with phenomenal precision. The experiments at the LHC will test the standard model in a new energy regime. To normalize the measurements and understand the potential discoveries of the LHC experiments it is often crucial to know the interaction rate - the absolute luminosity. The ATLAS (A Toroidal LHC ApparatuS) detector will measure luminosity by numerous methods. But for most of the methods only the relative luminosity is measured with good precision. The absolute scale has to be provided from elsewhere. Therefore ATLAS plans to measure the flux of protons scattered under very small angles as this flux relates directly and with good precision to the absolute luminosity. This will be done by the ALFA (Absolute Luminosity For ATLAS) detector. The detectors will be positioned about 240 m from the interac...

Jakobsen, Sune; Grafström, P; Joram, C

2010-01-01

225

The Luminosity Function of Galaxies in Compact Groups  

CERN Document Server

From R-band images of 39 Hickson compact groups (HCGs), we use galaxy counts to determine a luminosity function extending to M_R=-14.0, approximately two magnitudes deeper than previous compact group luminosity functions. We find that a single Schechter function is a poor fit to the data, so we fit a composite function consisting of separate Schechter functions for the bright and faint galaxies. The bright end is best fit with M^*=-21.6 and alpha=-0.52 and the faint end with M^*=-16.1 and alpha=-1.17. The decreasing bright end slope implies a deficit of intermediate luminosity galaxies in our sample of HCGs and the faint end slope is slightly steeper than that reported for earlier HCG luminosity functions. Furthermore, luminosity functions of subsets of our sample reveal more substantial dwarf populations for groups with x-ray halos, groups with tidal dwarf candidates, and groups with a dominant elliptical or lenticular galaxy. Collectively, these results support the hypothesis that within compact groups, the...

Hunsberger, S D; Zaritsky, D; Hunsberger, Sally D.; Charlton, Jane C.; Zaritsky, Dennis

1998-01-01

226

On the Luminosity Dependence of the Galaxy Pairwise Velocity Dispersion  

CERN Document Server

(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...

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

2006-01-01

227

Magnitude Gap Statistics and the Conditional Luminosity Function  

CERN Document Server

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...

More, Surhud

2012-01-01

228

Luminosity functions for very low mass stars and brown dwarfs  

Science.gov (United States)

A theoretical investigation of the luminosity function for low-mass objects to constrain the stellar initial mass function at the low-mass end is reported. The ways in which luminosity functions for low-mass stars are affected by star formation histories, brown dwarf and premain-sequence cooling rates and main-sequence mass luminosity relations, and the IMF are examined. Cooling rates and the mass-luminosity relation are determined through a new series of evolutionary calculations for very low mass stars and brown dwarfs in the range 0.05-0.50 solar mass. Model luminosity functions are constructed for specific comparison with the results of four recent observational surveys. The likelihood that the stellar mass function in the solar neighborhood is increasing at masses near the bottom of the main sequence and perhaps at lower masses is confirmed. In the most optimistic case, brown dwarfs contribute half of the local missing disk mass. The actual contribution is likely to be considerably less.

Laughlin, Gregory; Bodenheimer, Peter

1993-01-01

229

LHCb: LHCb Muon System Performance at High Luminosity  

CERN Multimedia

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...

Pinci, D

2013-01-01

230

The HerMES SPIRE submillimeter local luminosity function  

CERN Document Server

Local luminosity functions are fundamental benchmarks for high-redshift galaxy formation and evolution studies as well as for models describing these processes. Determining the local luminosity function in the submillimeter range can help to better constrain in particular the bolometric luminosity density in the local Universe, and Herschel offers the first opportunity to do so in an unbiased way by imaging large sky areas at several submillimeter wavelengths. We present the first Herschel measurement of the submillimeter 0luminosity function and infrared bolometric (8-1000 $\\mu$m) local luminosity density based on SPIRE data from the HerMES Herschel Key Program over 14.7 deg^2. Flux measurements in the three SPIRE channels at 250, 350 and 500 \\mum are combined with Spitzer photometry and archival data. We fit the observed optical-to-submillimeter spectral energy distribution of SPIRE sources and use the 1/V_{max} estimator to provide the first constraints on the monochromatic 250, 350 and ...

Vaccari, M; Franceschini, A; Altieri, B; Amblard, A; Arumugam, V; Auld, R; Aussel, H; Babbedge, T; Blain, A; Bock, J; Boselli, A; Buat, V; Burgarella, D; Castro-Rodriguez, N; Cava, A; Chanial, P; Clements, D L; Conley, A; Conversi, L; Cooray, A; Dowell, C D; Dwek, E; Dye, S; Eales, S; Elbaz, D; Farrah, D; Fox, M; Gear, W; Glenn, J; Solares, E A Gonzalez; Griffin, M; Halpern, M; Hatziminaoglou, E; Huang, J; Ibar, E; Isaak, K; Ivison, R J; Lagache, G; Levenson, L; Lu, N; Madden, S; Maffei, B; Mainetti, G; Mortier, A M J; Nguyen, H T; O'Halloran, B; Oliver, S J; Omont, A; Page, M J; Panuzzo, P; Papageorgiou, A; Pearson, C P; Perez-Fournon, I; Pohlen, M; Rawlings, J I; Raymond, G; Rigopoulou, D; Rizzo, D; Rodighiero, G; Roseboom, I G; Rowan-Robinson, M; Portal, M Sanchez; Schulz, B; Scott, Douglas; Seymour, N; Shupe, D L; Smith, A J; Stevens, J A; Symeonidis, M; Trichas, M; Tugwell, K E; Valiante, E; Valtchanov, I; Vigroux, L; Wang, L; Ward, R; Wright, G; Xu, C K; Zemcov, M

2010-01-01

231

Contribution of the accretion disk, hot corona, and obscuring torus to the luminosity of Seyfert galaxies: INTEGRAL and Spitzer observations  

CERN Document Server

We estimate the relative contributions of the supermassive black hole (SMBH) accretion disk, corona, and obscuring torus to the bolometric luminosity of Seyfert galaxies, using Spizter mid-infrared (MIR) observations of a complete sample of 68 nearby active galactic nuclei from the INTEGRAL all-sky hard X-ray (HX) survey. This is the first HX-selected (above 15 keV) sample of AGNs with complementary high angular resolution, high signal to noise, MIR data. Correcting for the host galaxy contribution, we find a correlation between HX and MIR luminosities: L_MIR L_HX^(0.74+/-0.06). Assuming that the observed MIR emission is radiation from an accretion disk reprocessed in a surrounding dusty torus that subtends a solid angle decreasing with increasing luminosity (as inferred from the declining fraction of obscured AGNs), the intrinsic disk luminosity, L_D, is approximately proportional to the luminosity of the corona in the 2-300 keV energy band, L_C, with the L_D/L_C ratio varying by a factor of 2.1 around a mea...

Sazonov, S; Goulding, A D; Hickox, R C; Gorjian, V; Werner, M W; Churazov, E; Krivonos, R; Revnivtsev, M; Sunyaev, R; Jones, C; Murray, S S; Vikhlinin, A; Fabian, A C; Forman, W R

2012-01-01

232

On the size-luminosity relation of AGN dust tori in the mid-infrared  

Science.gov (United States)

Context. Interferometric measurements in the mid-infrared have shown that the sizes of the warm dust distributions in active galactic nuclei (AGN) are consistent with their scaling with the square root of their luminosity. Aims: We carry out a more detailed analysis of this size-luminosity relation to investigate which of the general properties of the dusty tori in AGN can be derived from this relation. We are especially interested in the cases, where only a very small number of interferometric measurements are available and the sizes are directly calculated from the measured visibilities assuming a Gaussian brightness distribution. Methods: We improve the accuracy of the size-luminosity relation by adding a few additional size measurements from more recent interferometric observations and compare the measured sizes to those derived from hydrodynamical and radiative transfer models of AGN tori. Results: We find that a Gaussian approximation yields a reasonable estimate of the size of the brightness distribution, as long as the visibilities are within 0.2 ? V ? 0.9. The uncertainty in the size estimate depends on the true brightness distribution and is up to a factor of four for the models used in our investigation. The size estimates derived from the models are consistent with those determined from the measurements. However, the models predict a significant offset between the sizes derived for face-on (Seyfert 1 case) and edge-on (Seyfert 2 case) tori: the face-on tori should appear significantly more compact for the same luminosity. This offset is not observed in the current data, probably because of the large uncertainties and low statistics of the present interferometric measurements. Furthermore, we find a ratio of the mid- to near-infrared sizes of approximately 30, whereas the first probes the body of the torus and the second is an estimate of the inner rim. Conclusions: The size-luminosity relation of AGN tori using Gaussian size estimates is a very simple and effective tool to investigate the internal structure and geometry of AGN tori and obtain constraints on the differences between type 1 and type 2 AGN. However, to fully exploit the possibilities of investigating the nuclear distributions of gas and dust in AGN using this size-luminosity relation, more accurate interferometric measurements of a larger sample of AGN are needed. Based on observations with MIDI at the European Southern Observatory, Chile, programme numbers 060.A-9224(A), 074.B-0213(B), 075.B-0697(B), 076.B-0038(A), 076.B-0743(A,C), 077.B-0026(B), 078.B-0031(A), 079.B-0180(A), 080.B-0258(A), 081.D-0092(A) and 381.B-0240(A,B).

Tristram, K. R. W.; Schartmann, M.

2011-07-01

233

The Luminosity Function at z ~ 8 from 97 Y-band Dropouts: Inferences about Reionization  

Science.gov (United States)

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 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^\\star = -20.15^{+0.29}_{-0.38}, a faint-end slope of \\alpha = -1.87^{+0.26}_{-0.26}, and a number density of log _{10} \\phi ^\\star [{Mpc}^{-3}] = -3.24^{+0.25}_{-0.24}. Integrated down to M = -17.7, this luminosity function yields a luminosity density log _{10} \\epsilon [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.

Schmidt, Kasper B.; Treu, Tommaso; Trenti, Michele; Bradley, Larry D.; Kelly, Brandon C.; Oesch, Pascal A.; Holwerda, Benne W.; Shull, J. Michael; Stiavelli, Massimo

2014-05-01

234

Luminosity-dependent unification of Active Galactic Nuclei and the X-ray Baldwin effect  

CERN Document Server

The existence of an anti-correlation between the equivalent width (EW) of the narrow core of the iron Kalpha line and the luminosity of the continuum (i.e. the X-ray Baldwin effect) in type-I active galactic nuclei has been confirmed over the last years by several studies carried out with XMM-Newton, Chandra and Suzaku. However, so far no general consensus on the origin of this trend has been reached. Several works have proposed the decrease of the covering factor of the molecular torus with the luminosity (in the framework of the luminosity-dependent unification models) as a possible explanation for the X-ray Baldwin effect. Using the fraction of obscured sources measured by recent X-ray and IR surveys as a proxy of the half-opening angle of the torus, and the recent Monte-Carlo simulations of the X-ray radiation reprocessed by a structure with a spherical-toroidal geometry by Ikeda et al. (2009) and Brightman & Nandra (2011), we test the hypothesis that the X-ray Baldwin effect is related to the decreas...

Ricci, Claudio; Awaki, Hisamitsu; Petrucci, Pierre-Olivier; Ueda, Yoshihiro; Brightman, Murray

2013-01-01

235

Simulation Studies for a new ATLAS Inner Detector for the High-Luminosity LHC  

CERN Document Server

To maintain scientific progress, the LHC will require a major upgrade after 2020. The current plans include increasing the instantaneous luminosity by a factor of 5 (utilising luminosity levelling) beyond the original design value. This project is referred to as the HL-LHC (High Luminosity LHC), and its aim is to provide 3000 fb^{-1} of sqrt(s)=14 TeV proton-proton collisions in 10 to 12 years. The HL-LHC will be an extremely challenging experimental environment, with significantly higher particle fluxes, radiation doses and detector occupancies than experienced currently by the LHC experiments. The present ATLAS Inner Detector (ID) will not be suitable for operation in such conditions and will be completely replaced by a new, all-silicon Inner Tracker (ITk). The ITk must satisfy the following criteria, with respect to the current ID, in order to achieve the desired levels of physics performance: higher granularity, improved material budget and increased radiation hardness of the readout components. Currently...

Styles, N; The ATLAS collaboration

2012-01-01

236

Truncation of the Inner Accretion Disk around a Black Hole at Low Luminosity  

CERN Document Server

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 (Rin) can be made using iron emission lines that arise due to fluorescence of iron in the disk, and these indicate that Rin is very close to the black hole at high and moderate luminosities (near 1% of the Eddington luminosity, Ledd). 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 (RXTE) that extend iron line studies to 0.14% Ledd and show that Rin increases by a factor of >27 over the value found when GX 339-4 was bright. The exact value of Rin depends on the inclination of the inner disk (i), and we derive 90% confidence limits of Rin > 35 Rg at i = 0 degrees and Rin > 175 Rg at i = 30 degrees. This provides...

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

2009-01-01

237

The rest-frame optical luminosity functions of galaxies at 2  

CERN Document Server

[ABRIDGED] We present the rest-frame optical (B, V, and R-band) luminosity functions (LFs) of galaxies at 22 are consistent with those in the local LFs. The characteristic magnitudes are significantly brighter than the local values, while the measured values for Phi_star are a factor of ~5 smaller with respect to the local values. By integrating the LFs, we estimate the number and luminosity densities. We present for the first time the LF of Distant Red Galaxies (DRGs; defined here as z>2 sources with observed J-K>2.3). While DRGs and non-DRGs are characterized by similar LFs at the bright end, the faint-end slope of the non-DRG LF is much steeper than that of DRGs. Comparing the rest-frame V-band LF of non-DRGs to that inferred for Lyman break galaxies by Shapley et al. (2001), we find a significantly less steep faint-end slope. The contribution of DRGs to the global densities is 14%-25% in number and 22%-33% in luminosity. From the rest-frame U-V colors and stellar population synthesis models, we estimate t...

Marchesini, D; Quadri, R; Rudnick, G; Franx, M; Lira, P; Wuyts, S; Gawiser, E; Christlein, D; Toft, S; Marchesini, Danilo; Dokkum, Pieter van; Quadri, Ryan; Rudnick, Gregory; Franx, Marijn; Lira, Paulina; Wuyts, Stijn; Gawiser, Eric; Christlein, Daniel; Toft, Sune

2006-01-01

238

Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration  

CERN Document Server

In order to measure distances with minimal systematics using the correlation between galaxy luminosities and rotation rates it is necessary to adhere to a strict and tested recipe. We now derive a measure of rotation from a new characterization of the width of a neutral Hydrogen line profile. Additionally, new photometry and zero point calibration data are available. Particularly the introduction of a new linewidth parameter necessitates the reconstruction and absolute calibration of the luminosity-linewidth template. The slope of the new template is set by 267 galaxies in 13 clusters. The zero point is set by 36 galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we determine H0 = 75 km s-1 Mpc-1. Distances determined using the luminosity-linewidth calibration will contribute to the distance compendium Cosmicflows-2.

Tully, R Brent

2012-01-01

239

Reduction of beta* and increase of luminosity at RHIC  

Energy Technology Data Exchange (ETDEWEB)

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.

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

240

Global luminosity function of the Fornax dwarf elliptical galaxy  

International Nuclear Information System (INIS)

UK Schmidt plates in B and V are used to obtain the global luminosity function for the Fornax dwarf elliptical galaxy. Both functions are shown to provide evidence of structure in the giant branch. The results indicate that the old population of Fornax is similar to that of such moderately metal-poor clusters as M5 and M13, and they demonstrate the existence of a significant excess population of very bright stars over that seen in pure old systems. Theoretical luminosity functions of various ages and helium abundances are not found to provide good fits to the observed luminosity functions, suggesting that Fornax has had a star-formation history more complex than the two-burst models considered. 51 references

 
 
 
 
241

Bimodality in low luminosity E and S0 galaxies  

CERN Document Server

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 ...

Sansom, A E

2008-01-01

242

High time resolution luminosity profiles of Jellyfish (Super) Sprites  

Science.gov (United States)

We compare the time history of luminosity and VLF measurements associated with different classes of sprites. In particular we are interested in the larger "jellyfish, or super" sprites that are very bright, very brief duration sprites. Optical observations reveal these sprites are collections of multiple carrot sprites, comprised of both downward and upward propagating streamers. We find the time scales of super sprites are shorter than that for carrot sprites and column sprites. The exponential decrease in sprite luminosity has been related to the conductivity profile assumed for the middle atmosphere by [Barrington-Leigh et. al. (2002), doi: 10.1029/2001JA900117]. We investigate the possibility that the overall brighter and rapid decrease in jellyfish sprite luminosity compared to other types of sprites may be related to changes in the middle atmosphere conductivity, and/or in the driving electrostatic field associated with the causative lightning flash.

McHarg, M. G.; Ahrns, J.; Stenbaek-Nielsen, H. C.; Kammae, T.; Haaland, R. K.; Cummer, S. A.; Li, J.; Liu, N.; Yukman, P.

2011-12-01

243

Resolving the Luminosity Problem in Low-Mass Star Formation  

CERN Document Server

We determine the observational signatures of protostellar cores by coupling two-dimensional radiative transfer calculations with numerical hydrodynamical simulations that predict accretion rates that both decline with time and feature short-term variability and episodic bursts caused by disk gravitational instability and fragmentation. We calculate the radiative transfer of the collapsing cores throughout the full duration of the collapse, using as inputs the core, disk, and protostellar masses, radii, and mass accretion rates predicted by the hydrodynamical simulations. From the resulting spectral energy distributions, we calculate standard observational signatures (bolometric luminosity, bolometric temperature, ratio of bolometric to submillimeter luminosity) to directly compare to observations. We show that the accretion process predicted by these models reproduces the full spread of observed protostars in both Lbol - Tbol and Lbol - core mass space, including very low luminosity objects, provides a reason...

Dunham, Michael M

2011-01-01

244

The observational consequences of an intrinsic burst luminosity distribution  

International Nuclear Information System (INIS)

The Galactic monoluminosity gamma burst models of Jennings and White (1980) are generalized to encompass intrinsic burst luminosity distributions. LogN-LogS is markedly affected by distributions moderately peaked toward low luminosity and of dynamic range greater than about 0.01. Spherical or 'Halo' distributions, which are unacceptable for monoluminosity sources, are, together with Disk distributions, compatible with LogN-LogS observations when an intrinsic variation in burst luminosity is introduced. The generalized models are used in predicting source angular distributions versus LogS. It is found that neither Disk nor Halo geometries can reconcile the present LogN-LogS and angular position observations. The significance of this is analyzed

245

CLIC crab cavity design optimisation for maximum luminosity  

International Nuclear Information System (INIS)

The bunch size and crossing angle planned for CERN's compact linear collider CLIC dictate that crab cavities on opposing linacs will be needed to rotate bunches of particles into alignment at the interaction point if the desired luminosity is to be achieved. Wakefield effects, RF phase errors between crab cavities on opposing linacs and unpredictable beam loading can each act to reduce luminosity below that anticipated for bunches colliding in perfect alignment. Unlike acceleration cavities, which are normally optimised for gradient, crab cavities must be optimised primarily for luminosity. Accepting the crab cavity technology choice of a 12 GHz, normal conducting, travelling wave structure as explained in the text, this paper develops an analytical approach to optimise cell number and iris diameter.

246

ATLAS Future Plans: Upgrade and the Physics with High Luminosity  

Directory of Open Access Journals (Sweden)

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.

Rajagopalan S.

2013-05-01

247

Luminosity thresholds: effects of test chromaticity and ambient illumination.  

Science.gov (United States)

Color constancy is often modeled on the assumption that color appearance in natural scenes is a function of the visual system's estimates of surface reflectance. Some stimuli, however, do not look like illuminated surfaces. Instead, they appear to be self-luminous. We hypothesized that the appearance of luminosity occurs when the visual system estimates a reflectance spectrum that is outside the gamut of physically realizable surfaces. To test this idea, we measured luminosity thresholds as a function of stimulus chromaticity and illuminant spectral power distribution. Observers adjusted the luminance of a test patch until it just appeared self-luminous. The test patch was spot illuminated by a computer-controlled projection colorimeter viewed in an experimental room lit diffusely by computer-controlled theater lamps. Luminosity thresholds were determined for a number of test patch chromaticities under five experimental illuminants. The luminosity thresholds define a surface in color space. The shape of this surface depends on the illuminant. We were able to describe much of the luminosity threshold variation with a simple model whose parameters define an equivalent illuminant. In the context of our model, the equivalent illuminant may be interpreted as the illuminant perceived by the observer. As part of our model calculations we generalized the classic notion of optimal stimuli by incorporating linear-model constraints. Given the equivalent illuminant, the model predicts that a patch will appear self-luminous when it is not consistent with any physically realizable surface seen under that illuminant. In addition, we show that much of the variation of the equivalent illuminant with the physical illuminant can be modeled with a simple linearity principle. The fact that our model provides a good account of our data extends the physics-based approach to judgements of self-luminosity. This in turn might be taken as support for the notion that the visual system has internalized the physics of reflectance. PMID:8627410

Speigle, J M; Brainard, D H

1996-03-01

248

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

Science.gov (United States)

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.

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

2011-01-01

249

A high-energy high-luminosity ?+ - ?- collider  

International Nuclear Information System (INIS)

We present a candidate design for a high-energy high luminosity ?+-? collider, with Ecm = 4 TeV, L = 1034 cm-2S-1, using only existing technology. The design uses a rapid-cycling medium-energy proton synchrotron, which produces proton beam pulses which are focused onto two ?- producing targets, with two ?-decay transport lines producing ?+'s and ?-'. The ?'s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal ? collection and cooling; innovations with these goals are included

250

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

251

History of Star Formation Rate and Luminosity Density of Galaxies  

CERN Document Server

We have computed the time evolution of bolometric, far-infrared, Halpha line, ultraviolet (both intrinsic and escaping the star forming region) and the nonthermal radio continuum luminosities for continuous and constant star formation. The luminosity rises to a plateau value and declines after the termination of starburst, but only gradually. The time evolution profiles are broad and different for different star formation indicators. The broad profiles lead to uncertainties in the star formation rate derived depending on the initial mass function, duration of starburst, its distribution and the observational epoch.

Rengarajan, T N

2003-01-01

252

Parameter Space for the LHC High-Luminosity Upgrade  

CERN Document Server

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.

Bruning, Oliver

2012-01-01

253

LUCID, the Luminosity Monitor for ATLAS - A Status Report  

CERN Document Server

In addition to the main ATLAS detector, three smaller systems are being built to provide good coverage in the very forward region . These are closely connected to the luminosity determination in ATLAS, but are also foreseen to study forward physics. If ordered according to their distance from the ATLAS interaction point, the first system is LUCID the main luminosity monitor of ATLAS located at a distance of 17 m from the interaction point. This detector is now nearing the end of construction at CERN. The LUCID detector and its status with regards to construction, testing and installation are described in this document.

Pinfold, James

2008-01-01

254

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)

255

Gamma-Ray Luminosity Function of Blazars and the Cosmic Gamma-Ray Background: Evidence for the Luminosity Dependent Density Evolution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We present a comprehensive study for the gamma-ray luminosity function (GLF) of blazars and their contribution to the extragalactic diffuse gamma-ray background (EGRB). Radio and gamma-ray luminosity correlation is introduced to take into account the radio detectability which is important for the blazar identification. Previous studies considered only pure luminosity evolution (PLE) or pure density evolution, but we introduce the luminosity dependent density evolution (LDDE)...

Narumoto, Takuro; Totani, Tomonori

2006-01-01

256

LHC Report: Boost in bunches brings record luminosity  

CERN Multimedia

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...

2011-01-01

257

High Luminosity Issues for DAPhNE Upgrade  

CERN Document Server

We give an overview of presentations and discussions during the Accelerator Working Group Session dedicated to High Luminosity Issues for a future upgrade of the Frascati e+e- Phi-Factory DAPhNE at the Workshop "e+e- in the 1-2 GeV range: Physics and Accelerator Prospects" held at Alghero (Italy) on 10-13 September 2003.

Ruggiero, F

2004-01-01

258

High Luminosity Issues for DAPhNE Upgrade  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We give an overview of presentations and discussions during the Accelerator Working Group Session dedicated to High Luminosity Issues for a future upgrade of the Frascati e+e- Phi-Factory DAPhNE at the Workshop "e+e- in the 1-2 GeV range: Physics and Accelerator Prospects" held at Alghero (Italy) on 10-13 September 2003.

Ruggierocern, F.; Zobovlnf Infn, M.

2014-01-01

259

A Single Bremsstrahlung Monitor to Measure Luminosity at LEP  

CERN Multimedia

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...

2002-01-01

260

A new record peak luminosity for the LHC  

CERN Multimedia

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...

CERN Bulletin

2010-01-01

 
 
 
 
261

Redshift Distribution and Luminosity Functions of Obscured and Unobscured Quasars  

Science.gov (United States)

We have undertaken a spectroscopic survey of luminous AGNs and quasars selected in the mid-infrared from Spitzer IRAC surveys. Mid-infrared selection is much less biased with respect to obscuration than optical techniques, and hence enables the discovery of obscured quasars as well as normal, unobscured ones. Our survey is designed to include brighter 24 micron sources over wider areas and also to go to much lower fluxes limits in more limited spatial regions to allow us to disentangle dependences on redshift and luminosity. We have used 4m class telescopes to obtain spectra of the brighter 24 micron targets (targeting high luminosity objects at low z), and 8m class telescopes to identify lower luminosity high-redshift obscured quasars by targeting the fainter 24 micron targets. Fron this survey we have been able to compile a statistically complete sample of ~ 500 AGN, both obscured and unobscured, over a large range of redshift and luminosity. We find that obscured objects outnumber unobscured AGN with an obscured fraction ranging from ~ 90% to ~ 50%. For the most luminous quasars, the number densities of unobscured quasars peaks at z ~ 2.8, and for the obscured objects, the peak may be at slightly higher redshift.

Ridgway, Susan E.; Lacy, M.; Petric, A.; Sajina, A.; Urrutia, T.; Gates, E. L.

2014-07-01

262

Rotation Velocities of Two Low Luminosity Field Galaxies  

CERN Document Server

We present H-alpha rotation curves of two low luminosity field galaxies with r-band absolute magnitudes M_r=-13.9^{+0.8}_{-0.5} and M_r=-14.7^{+0.3}_{-0.2} (for h=0.7; the large error bars reflect distance uncertainties). Most previously studied galaxies in this luminosity range are members of groups defined by brighter galaxies, but these two systems, selected from Blanton et al.'s (2004) sample of low luminosity galaxies in the Sloan Digital Sky Survey (SDSS), appear to have no bright companions. The measured rotation speeds at the outer extent of the H-alpha rotation curves, 34.8+/-3.8 km/s and 30.9+/-7.2 km/s, are larger than the values of 16.0^{+6.1}_{-5.4} km/s and 20.9^{+6.2}_{-5.2} km/s predicted by extrapolating the inverse Tully-Fisher relation of luminous SDSS galaxies to these faint luminosities. However, a previous HI measurement of the first galaxy shows that it has a gas mass similar to its stellar mass, and the total baryonic mass is consistent with that predicted by McGaugh et al.'s (2000) "b...

Pizagno, J; Weinberg, D H; Bahcall, Neta A; Brinkmann, J; Pizagno, James; Blanton, Michael R.; Weinberg, David H.; Bahcall, Neta A.; Brinkmann, Jon

2004-01-01

263

Direct Oxygen Abundances for Low Luminosity LVL Galaxies  

CERN Document Server

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....

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

264

A scheme to improve the low energy luminosity in LEP  

International Nuclear Information System (INIS)

In the design of large electron positron colliding beam facilities, it has become customary to use a certain optimization procedure to establish desired beam performance. The results of this procedure are the minimum requirements in terms of RF-power, bending radius and focusing to achieve a desired luminosity at a given energy. This procedure, however, neglects the optimization of the storage ring performance below and above that design energy. Below the design energy the luminosity is optimized by lowering the tune or by use of wiggler magnets. Both methods result in a luminosity scaling like L /approximately/ E2. To improve the luminosity expectation above the design energy, the optimized lattice design has to be changed as has been done in the design of PETRA and PEP. In these designs the cell length was chosen to be only half as long as the optimized cell which requires twice as many quadrupoles. With the reduced cell length it is possible to increase the tune of the storage ring by a much larger amount than it would be possible with a larger lattice cell

265

Physics of a high-luminosity Tau-Charm Factory  

International Nuclear Information System (INIS)

This paper highlights the physics capabilities of a Tau-Charm Factory; i.e., high luminosity (?1033cm-2s-1) e+e- collider operating in the center-of-mass energy range of 3-5 GeV, with a high-precision, general-purpose detector. Recent developments in ? and charm physics are emphasized

266

Absorbers for the high luminosity insertions of the LHC  

International Nuclear Information System (INIS)

At design luminosity and inelastic cross section ?pp = 80mb there are 8 x 108 inelastic collisions per second at the high luminosity interaction points IP1 and IP5 of the LHC. These interactions give rise to ? 0.9 kW of power in collision products leaving an IP in each direction. The inelastic collision power carried off by neutrals, mostly neutrons and photons, in each direction and intercepted by neutral absorbers (TAN) has been estimated with the MARS13 code to be 210W. Similarly the collision power escaping the beam tube and incident on the front face of the inner triplet quadrupole absorber (TAS) has been estimated to be ? 270W, mostly carried by charged pions and photons. Special purpose absorbers must intercept this power to prevent quenching the inner triplet quadrupoles (Q1 to Q3) and the twin aperture magnets outside the second beam separation dipole D2. Because of the high incident flux of collision products near zero degrees the absorbers are natural places to consider for the location of radiation hard gas ionization detectors which could be used for: (1) measurement of luminosity, (2) measurement of the beam transverse dimensions at the IP and (3) feedback control of the colliding beam centers at the IP's to maximize luminosity. The following sections describe: (1) the conceptual design of the absorbers, (2) the radiation deposition and activation calculations and (3) the possibilities for instrumentation

267

TOTAL INFRARED LUMINOSITY ESTIMATION OF RESOLVED AND UNRESOLVED GALAXIES  

International Nuclear Information System (INIS)

The total infrared (TIR) luminosity from galaxies can be used to examine both star formation and dust physics. We provide here new relations to estimate the TIR luminosity from various Spitzer bands, in particular from the 8 ?m and 24 ?m bands. To do so, we use data for 45'' subregions within a subsample of nearby face-on spiral galaxies from the Spitzer Infrared Nearby Galaxies Survey (SINGS) that have known oxygen abundances as well as integrated galaxy data from the SINGS, the Local Volume Legacy survey (LVL), and Engelbracht et al. samples. Taking into account the oxygen abundances of the subregions, the star formation rate intensity, and the relative emission of the polycyclic aromatic hydrocarbons at 8 ?m, the warm dust at 24 ?m, and the cold dust at 70 ?m and 160 ?m, we derive new relations to estimate the TIR luminosity from just one or two of the Spitzer bands. We also show that the metallicity and the star formation intensity must be taken into account when estimating the TIR luminosity from two wave bands, especially when data longward of 24 ?m are not available.

268

Finding and characterising WHIM structures using the luminosity density method  

CERN Document Server

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...

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

269

Luminosity functions for two-photon processes in e+e- collisions  

International Nuclear Information System (INIS)

An analysis is given of the QED factors relating the cross section for e e ? e e X to the virtual 2-photon collision ?*?* ? X. Only transverse photons are considered, but no kinematical approximations are made. The cases where none, one or both of the scattered electrons are detected at angles >> msub(e)/E (E = beam energy) are separately considered. A full discussion is given of the kinematical restrictions necessary to arrive at factorisible Equivalent Photon Approximation formulae, and quantitative comparisons are given. Also discussed are the rapidity distribution of the produced system X and restrictions on the effective two-photon luminosity due to angular cuts on produced particles. (orig.)

270

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

271

Status and Outlook for the RHIC Luminosity Upgrade  

Science.gov (United States)

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. )

Bai, Mei

2010-02-01

272

Determination of the absolute luminosity at the LHC  

Energy Technology Data Exchange (ETDEWEB)

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

White, S.

2010-07-01

273

DIRECT OXYGEN ABUNDANCES FOR LOW-LUMINOSITY LVL GALAXIES  

Energy Technology Data Exchange (ETDEWEB)

We present MMT spectroscopic observations of H II regions in 42 low luminosity galaxies in the Spitzer Local Volume Legacy survey. For 31 of the 42 galaxies in our sample, we were able to measure the temperature sensitive [O III] {lambda}4363 line at a strength of 4{sigma} or greater, and thus determine oxygen abundances using the 'direct' method. Our results provide the first 'direct' estimates of oxygen abundance for 19 of these galaxies. 'Direct' oxygen abundances were compared to B-band luminosities, 4.5 {mu}m luminosities, and stellar masses in order to characterize the luminosity-metallicity and mass-metallicity relationships at low luminosity. We present and analyze a 'Combined Select' sample composed of 38 objects (drawn from a sub-set of our parent sample and the literature) with 'direct' oxygen abundances and reliable distance determinations (based on the tip of the red giant branch or Cepheid variables). Consistent with previous studies, the B band and 4.5 {mu}m luminosity-metallicity relationships for the 38 objects were found to be 12 + log(O/H) = (6.27 {+-} 0.21) + (- 0.11 {+-} 0.01)M{sub B} and 12 + log(O/H) = (6.10 {+-} 0.21) + (- 0.10 {+-} 0.01)M{sub [4.5]} with dispersions of {sigma} = 0.15 and 0.14, respectively. The slopes of the optical and near-IR L-Z relationships have been reported to be different for galaxies with luminosities greater than that of the LMC. However, the similarity of the slopes of the optical and near-IR L-Z relationships for our sample probably reflects little influence by dust extinction in the low luminosity galaxies. For this sample, we derive a mass-metallicity relationship of 12 + log(O/H) = (5.61 {+-} 0.24) + (0.29 {+-} 0.03)log (M{sub *}), which agrees with previous studies; however, the dispersion ({sigma} = 0.15) is not significantly lower than that of the L-Z relationships. Because of the low dispersions in these relationships, if an accurate distance is available, the luminosity of a low luminosity galaxy is often a better indicator of metallicity than that derived using certain 'strong-line' methods, so significant departures from the L-Z relationships may indicate that caution is prudent in such cases. With these new 'direct' metallicities we also revisit the 70/160 {mu}m color metallicity relationship. Additionally, we examine N/O abundance trends with respect to oxygen abundance and B - V color. We find a positive correlation between N/O ratio and B - V color for 0.05 {approx}< B - V {approx}< 0.75: log (N/O) = (1.18 {+-} 0.9) Multiplication-Sign (B - V) + (- 1.92 {+-} 0.08), with a dispersion of {sigma} = 0.14, which is in agreement with previous studies.

Berg, Danielle A.; Skillman, Evan D. [Institute for Astrophysics, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455 (United States); Marble, Andrew R.; Engelbracht, Charles W. [Steward Observatory, University of Arizona, 933 N Cherry Ave., Tucson, AZ 85721 (United States); Van Zee, Liese [Astronomy Department, Indiana University, 727 East 3rd Street, Bloomington, IN 47405 (United States); Lee, Janice C. [STScI, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Kennicutt, Robert C. Jr. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Calzetti, Daniela [Department of Astronomy, University of Massachusetts, 710 North Pleasant Street, Amherst, MA 01003 (United States); Dale, Daniel A. [Department of Physics and Astronomy, University of Wyoming, 1000 E. University, Laramie, WY 82071 (United States); Johnson, Benjamin D., E-mail: berg@astro.umn.edu, E-mail: skillman@astro.umn.edu, E-mail: cengelbracht@as.arizona.edu, E-mail: amarble@nso.edu, E-mail: vanzee@astro.indiana.edu, E-mail: jlee@stsci.edu, E-mail: calzetti@astro.umass.edu, E-mail: ddale@uwyo.edu, E-mail: johnson@iap.fr [Institut d' Astrophysique de Paris, UMR 7095, 98 bis Bvd Arago, 75014 Paris (France)

2012-08-01

274

GAMMA-RAY BURST LUMINOSITY RELATIONS: TWO-DIMENSIONAL VERSUS THREE-DIMENSIONAL CORRELATIONS  

International Nuclear Information System (INIS)

The large scatters of luminosity relations of gamma-ray bursts (GRBs) have been one of the most important reasons that prevent the extensive applications of GRBs in cosmology. In this paper, we extend the two-dimensional (2D) luminosity relations with ?lag, V, E peak, and ?RT as the luminosity indicators to three dimensions (3D) using the same set of luminosity indicators to explore the possibility of decreasing the intrinsic scatters. We find that, for the 3D luminosity relations between the luminosity and an energy scale (Epeak) and a timescale (?lag or ?RT), their intrinsic scatters are considerably smaller than those of corresponding 2D luminosity relations. Enlightened by the result and the definition of the luminosity (energy released in units of time), we discussed possible reasons behind this result, which may give us helpful suggestions on seeking more precise luminosity relations for GRBs in the future.

275

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

CERN Document Server

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...

Rakshit, Suvendu

2014-01-01

276

The K Band Luminosity Function of High Redshift Clusters  

CERN Document Server

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.

Ellis, S C

2003-01-01

277

A practical high-energy high-luminosity ?+ - ?- collider  

International Nuclear Information System (INIS)

We present a candidate design for a high-energy high-luminosity ?+-? collider, with Ecm = 4 TeV, L = 3 x 104cm-2s-1, using only existing technology. The design uses a rapid-cycling medium-energy proton synchrotron, which produces proton beam pulses which are focused onto two ?-producing targets, with two ?-decay transport lines producing ?+'s. The ?'s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal ? collection and cooling; innovations with these goals are presented, and future plans for collider development are discussed. This example demonstrates a novel high-energy collider type, which will permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders

278

L1 track triggering at CMS for High Luminosity LHC  

Science.gov (United States)

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.

Skinnari, L.

2014-10-01

279

Maximum Likelihood Random Galaxy Catalogues and Luminosity Function Estimation  

CERN Document Server

We present a new algorithm to generate a random (unclustered) version of an observational galaxy redshift catalogue. It takes into account both galaxy evolution and the perturbing effects of large scale structure. The key to the algorithm is a new maximum likelihood (ML) method for jointly estimating both the luminosity function (LF) and the overdensity as a function of redshift. The random catalogue algorithm then works by cloning each galaxy in the original catalogue, with the number of clones determined by the ML solution. Each of these cloned galaxies is then assigned a random redshift uniformly distributed over the accessible survey volume, taking account of the survey magnitude limit(s) and, optionally, both luminosity and number density evolution. The resulting random catalogues, which can be employed in traditional estimates of galaxy clustering, make fuller use of the information available in the original catalogue and hence are superior to simply fitting a functional form to the observed redshift di...

Cole, Shaun

2011-01-01

280

Using Micromegas in ATLAS to Monitor the Luminosity  

CERN Document Server

Five small prototype micromegas detectors were positioned in the ATLAS detector during LHC running at $\\sqrt{s} = 8\\, \\mathrm{TeV}$. A $9\\times 4.5\\, \\mathrm{cm^2}$ two-gap detector was placed in front of the electromagnetic calorimeter and four $9\\times 10\\, \\mathrm{cm^2}$ detectors on the ATLAS Small Wheels, the first station of the forward muon spectrometer. The one attached to the calorimeter was exposed to interaction rates of about $70\\,\\mathrm{kHz/cm^2}$ at ATLAS luminosity $\\mathcal{L}=5\\times 10^{33}\\,\\mathrm{cm^{-2}s^{-1}}$ two orders of magnitude higher than the rates in the Small Wheel. We compare the currents drawn by the detector installed in front of the electromagnetic calorimeter with the luminosity measurement in ATLAS experiment.

The ATLAS collaboration

2013-01-01

 
 
 
 
281

Optical and IR luminosity functions of IRAS galaxies  

International Nuclear Information System (INIS)

The optical and infrared luminosity functions are determined for a 60 micron flux-limited sample of 68 IRAS galaxies covering a total area of 150 deg sq. The IR function is in good agreement with that obtained by other authors. The shape of the optical luminosity function is similar to that of optically selected galaxy samples. The integrated light of most objects in the sample have (NII) to H alpha line flux ratios characteristic of HII-region galaxies. In the absolute magnitude range M sub J = -18, -22 about 14% of late-type galaxies are IRAS galaxies. The apparent companionship frequency is about twice as large as that for a comparable sample of non-IRAS late-type galaxies

282

Silicon Sensors for Trackers at High-Luminosity Environment  

CERN Document Server

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 ...

Peltola, Timo

2014-01-01

283

Metallicity effects on synthetic Cepheid Period-Luminosity relations  

CERN Document Server

On the basis of new theoretical results useful predictions concerning the Period-Luminosity (PLR) and Period-Luminosity-Color (PLCR) relations both for optical and infrared magnitudes are presented. It is shown that, following the dependence of the instability strip on metallicity, there is a non negligible dependence of the PLRs and PLCRs on the metallicity of the pulsating stars, mainly for optical bands. In particular theoretical results predict a dependence of the PLR on metals which is reversed with respect to current empirical evaluations. To give a possible explanation for this discrepancy the typical observational procedures used to estimate extragalactic distances through Cepheid PLRs are here tested, with the aim of disentangling, if possible, the reddening and metallicity effects. To this purpose, synthetic PLRs for different metallicities were produced and treated as typical observational samples.

Musella, I

1999-01-01

284

L1 Track Triggering at CMS for High Luminosity LHC  

CERN Document Server

The High Luminosity LHC (HL-LHC) is expected to deliver luminosities of $5 \\times 10^{34}$~cm$^{-2}$s$^{-1}$, 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.

Skinnari, Louise

2014-01-01

285

Fast Polycrystalline-CdTe Detectors for LHC Luminosity Measurements  

CERN Document Server

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...

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

2002-01-01

286

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

287

The VIMOS-VLT Deep Survey: Evolution of the galaxy luminosity function up to z=2 in first epoch data  

CERN Document Server

We investigate the evolution of the galaxy luminosity function from the VIMOS-VLT Deep Survey (VVDS) from the present to z=2 in five (U, B, V, R and I) rest-frame band-passes. We use the first epoch VVDS deep sample of 11,034 spectra selected at 17.5 <= I_{AB} <= 24.0, on which we apply the Algorithm for Luminosity Function (ALF), described in this paper. We observe a substantial evolution with redshift of the global luminosity functions in all bands. From z=0.05 to z=2, we measure a brightening of the characteristic magnitude M* included in the magnitude range 1.8-2.4, 1.6-2.2, 1.0-1.7, 0.9-1.6 and 0.8-1.4 in the U, B, V, R and I rest-frame bands, respectively. We confirm this differential evolution of the luminosity function with rest-frame wavelength, from the measurement of the comoving density of bright galaxies (M < M*(z=0.1)). This density increases by a factor of around 2.5, 2.2, 1.7, 1.4, 1.3 between z=0.05 and z=1 in the U, B, V, R, I bands, respectively. We also measure a possible steepeni...

Ilbert, O; Zucca, E; Bardelli, S; Arnouts, S; Zamorani, G; Pozzetti, L; Bottini, D; Garilli, B; Le Brun, V; Lefèvre, O; MacCagni, D; Picat, J P; Scaramella, R; Scodeggio, M; Vettolani, G; Zanichelli, A; Adami, C; Arnaboldi, M; Bolzonella, M; Cappi, A; Charlot, S; Contini, T; Foucaud, S; Franzetti, P; Gavignaud, I; Guzzo, L; Iovino, A; McCracken, H J; Marano, B; Marinoni, C; Mathez, G; Mazure, A; Meneux, B; Merighi, R; Paltani, S; Pellò, R; Pollo, A; Radovich, M; Bondi, M; Bongiorno, A; Busarello, G; Ciliegi, P; Mellier, Y; Merluzzi, P; Ripepi, V; Rizzo, D

2004-01-01

288

A new model of galaxy formation: How sensitive are predicted galaxy luminosities to the choice of SPS model?  

CERN Document Server

We present a new release of the GALFORM semi-analytical model of galaxy formation and evolution, which exploits a Millennium Simulation-class N-body run performed with the WMAP7 cosmology. We use this new model to study the impact of the choice of stellar population synthesis (SPS) model on the predicted evolution of the galaxy luminosity function. The semi-analytical model is run using seven different SPS models. In each case we obtain the rest-frame luminosity function in the far-ultra-violet, optical and near-infrared (NIR) wavelength ranges. We find that both the predicted rest-frame ultra-violet and optical luminosity function are insensitive to the choice of SPS model. However, we find that the predicted evolution of the rest-frame NIR luminosity function depends strongly on the treatment of the thermally pulsating asymptotic giant branch (TP-AGB) stellar phase in the SPS models, with differences larger than a factor of 2 for model galaxies brighter than K(AB)-5logh<-22 (about L* for 0 < z < 1....

V.,; Lacey, C G; Baugh, C M; Lagos, C D P; Helly, J; Campbell, D J R

2013-01-01

289

LHC Abort Gap Cleaning Studies During Luminosity Operation  

Energy Technology Data Exchange (ETDEWEB)

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.

Gianfelice-Wendt, E.; /Fermilab; Bartmann, W.; Boccardi, A.; Bracco, C.; Bravin, E.; Goddard, B.; Hofle, W.; Jacquet, D.; Jeff, A.; Kain, V.; Meddahi, M.; /CERN

2012-05-11

290

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

291

Constraints on the Spatial Distribution and Luminosity function of GRBs  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The distance scale to gamma ray bursts has been a subject of scientific debate for almost thirty years. Up to the discovery of afterglows only indirect methods could be used to constrain the distance scale to this objects. I review some of these results, and show the current limits on the spatial distribution and luminosity function of GRBs. The results obtained with different methods indicate that gamma-ray bursts lie at the typical redshifts $z_{ave}$ between 1 and 2, howe...

Bulik, Tomasz

1999-01-01

292

LHC abort gap cleaning studies during luminosity operation  

CERN Document Server

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.

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

293

The luminosity function and the colours of the solar neighbourhood  

International Nuclear Information System (INIS)

A mean luminosity function for the Solar Neighbourhood has been derived in order to describe the photometric aspect of our stellar system. The contribution to the UBV bands in Johnson's system due to the various stellar sequences has been evaluated. The results in UBV colours for the Solar Neighbourhood are not univocally determined, thus requiring a new determination of the distribution function of stellar densities and of the relative frequencies of different star sequences

294

Positron injectors for high-luminosity storage-ring colliders  

International Nuclear Information System (INIS)

This paper reports on high-luminosity B-factories utilizing storage rings operating at unequal energies which require high-energy, low-emittance sources of positrons, and electrons suitable to fill the storage rings. As an example, consider the proposed characteristics of a collider with a luminosity of 1034 cm-2s-1 using the PEP facility at SLAC as studied by LBL (Apiary-III) and summarized. The collider consists of two rings, a large 9-GeV ring (PEP or a modification thereof) plus a 3.1-GeV ring of one-third the circumference, each with a circulating current of 3 A. Ideally, the time to fill the positron ring should be much shorter than the luminosity lifetime (set by the size of the low-energy ring). Since the luminosity lifetime of the collider is not expected to be very high, the PEP-based B-factory should have a powerful, dedicated injector. In the estimate of the characteristics of the injection system the maximum time for a complete fill of the positron ring is taken as ?100 seconds. In the design of the injection system several choices are possible: injection by linacs at full energy of the rings or use of an intermediate booster synchrotron; accelerating e+ and e- to high energy using conventional linacs or using high-gradient linacs plus gigawatt power RF-sources being developed for linear colliders; and using a conventional (warm magnet) damping ring for cooling the positron beam at an intermediate eg the positron beam at an intermediate energy or a full energy ring with a radius equal to that of the low-energy ring

295

Luminosity Upgrade of CLIC LHC ep/gp Collider  

CERN Document Server

An energy frontier or QCD Explorer ep and collider can be realized by colliding high-energy photons generated by Compton backscattered off a CLIC electron beam, at either 75 GeV or 1.5 TeV, with protons or ions stored in the LHC. In this study we discuss a performance optimization of this type of collider by tailoring the parameters of both CLIC and LHC. An estimate of the ultimately achievable luminosity is given.

Aksakal, H; Nergiz, Z; Schulte, D; Zimmermann, F

2007-01-01

296

Luminous Satellites. II. Spatial Distribution, Luminosity Function, and Cosmic Evolution  

Science.gov (United States)

We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log10[M*h/M ?] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R)\\propto R^{\\gamma _p}, we find ?p = -1.1 ± 0.3. We find no dependency of ?p on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

Nierenberg, A. M.; Auger, M. W.; Treu, T.; Marshall, P. J.; Fassnacht, C. D.; Busha, Michael T.

2012-06-01

297

LUMINOUS SATELLITES. II. SPATIAL DISTRIBUTION, LUMINOSITY FUNCTION, AND COSMIC EVOLUTION  

Energy Technology Data Exchange (ETDEWEB)

We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies (log{sub 10}[M*{sub h}/M{sub Sun }] > 10.5) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology, and satellite luminosity. Exploiting the depth and resolution of the COSMOS Hubble Space Telescope images, we detect satellites up to 8 mag fainter than the host galaxies and as close as 0.3 (1.4) arcsec (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that P(R){proportional_to}R{sup {gamma}{sub p}}, we find {gamma}{sub p} = -1.1 {+-} 0.3. We find no dependency of {gamma}{sub p} on host stellar mass, redshift, morphology, or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is dependent on its stellar mass, with more massive galaxies hosting significantly more satellites. Furthermore, high-mass late-type hosts have significantly fewer satellites than early-type galaxies of the same stellar mass, possibly indicating that they reside in more massive halos. No significant evolution in the number of satellites per host is detected. The cumulative luminosity function of satellites is qualitatively in good agreement with that predicted using SubHalo Abundance Matching techniques. However, there are significant residual discrepancies in the absolute normalization, suggesting that properties other than the host galaxy luminosity or stellar mass determine the number of satellites.

Nierenberg, A. M.; Treu, T. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Auger, M. W. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB30HA (United Kingdom); Marshall, P. J. [Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Fassnacht, C. D. [Department of Physics, University of California, Davis, CA 95616 (United States); Busha, Michael T., E-mail: amn01@physics.ucsb.edu [Institute for Theoretical Physics, University of Zuerich, Zuerich (Switzerland)

2012-06-20

298

Parallax and Luminosity Measurements of an L Subdwarf  

CERN Document Server

We present the first parallax and luminosity measurements for an L subdwarf, the sdL7 2MASS J05325346+8246465. Observations conducted over three years by the USNO infrared astrometry program yield an astrometric distance of 26.7+/-1.2 pc and a proper motion of 2.6241+/-0.0018"/yr. Combined with broadband spectral and photometric measurements, we determine a luminosity of log(Lbol/Lsun) = -4.24+/-0.06 and Teff = 1730+/-90 K (the latter assuming an age of 5-10 Gyr), comparable to mid-type L field dwarfs. Comparison of the luminosity of 2MASS J05325346+8246465 to theoretical evolutionary models indicates that its mass is just below the sustained hydrogen burning limit, and is therefore a brown dwarf. Its kinematics indicate a ~110 Myr, retrograde Galactic orbit which is both eccentric (3 <~ R <~ 8.5 kpc) and extends well away from the plane (Delta_Z = +/-2 kpc), consistent with membership in the inner halo population. The relatively bright J-band magnitude of 2MASS J05325346+8246465 implies significantly r...

Burgasser, Adam J; Lépine, Sébastien; Munn, Jeffrey A; Luginbuhl, Christian B; Henden, Arne A; Guetter, Harry H; Canzian, Blaise C

2007-01-01

299

The rate and luminosity function of Short GRBs  

International Nuclear Information System (INIS)

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 ? 8 to ? 30h703Gpc-3yr-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 1049erg/sec. Weaker bursts may exist but if so they are hardly detected by BATSE or Swift and hence their rate is very weakly constrained by current observations. Thus the rate of mergers that lead to a detection of a gravitational radiation signal might be even higher

300

Photometric observations of SARS clusters: Galaxy Luminosity Profiles  

CERN Document Server

We have analyzed CCD images of 14 Abell clusters in the R filter of the SARS survey (Way et al 2004), with cz<40000kms^{-1}. We have obtained the luminosity profiles for 507 galaxies of which 232 (46%) have known redshifts. In order to fit the luminosity profiles we used the de Vaucouleurs law for bulge systems, an exponential profile for disk systems and we have also fitted the Sersic's law (r^n) to all galaxy profiles. We have found that 162 (32%) galaxies in the sample have pure r^{1/4} profiles, 168 (33%) have pure exponential profiles, while 93 (18%) galaxies have luminosity profiles that are well fitted by a combination of both bulge and disk profiles. On the other hand, we could not fit the classical bulge + disk profile to the remaining 84 (17%) galaxies of the sample. For such cases we have only used the Sersic law. We have also analyzed how seeing and sky cleaning affect the structural and photometric parameters obtained through profile fitting. In addition, we have studied several relations betw...

Coenda, V; Muriel, H; Quintana, H; Infante, L; Lambas, D G

2004-01-01

 
 
 
 
301

Status of the luminosity monitor for the PANDA experiment  

International Nuclear Information System (INIS)

A good luminosity monitoring is crucial for the PANDA experiment at the planned antiproton accelerator HESR (FAIR, Darmstadt, Germany). For the measurement of the luminosity one can use the elastic antiproton-proton scattering at extreme forward angles. This exploits the fact that the elastic scattering in the range of very small momentum transfer (and thus very small scattering angle) can be calculated exactly from QED. At larger scattering angles the hadronic component of the elastic scattering dominates and this has to be taken from measurements. Unfortunately there are no or only a few data with large uncertainties available in the momentum range we need for PANDA. The current design for the luminosity monitor are four planes of eight double-sided silicon microstrip detectors with trapezoidal shape. The detector itself has an angular acceptance from 3 to 8 mrad and good spatial resolution due to using sensors with high resolution (50 ?m pitch). An overview of the basic concept and Monte Carlo based performance studies within the PANDARoot framework are presented.

302

Luminosity Functions of Young Clusters: Modeling the Substellar Mass Regime  

CERN Document Server

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...

Allen, P R; Körner, D W; Reid, I N

2003-01-01

303

An ionization chamber shower detector for the LHC luminosity monitor  

CERN Document Server

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...

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

304

Luminosity Evolution of Rotation-powered Gamma-ray Pulsars  

CERN Document Server

We investigate the electrodynamic structure of a pulsar outer-magnetospheric particle accelerator and the resultant gamma-ray emission. By considering the condition for the accelerator to be self-sustained, we derive how the trans-magnetic-field thickness of the accelerator evolves with the pulsar age. It is found that the thickness is small but increases steadily if the neutron-star envelope is contaminated by sufficient light elements. For such a light element envelope, the gamma-ray luminosity of the accelerator is kept approximately constant as a function of age in the initial ten thousand years, forming the lower bound of the observed distribution of the gamma-ray luminosity of rotation-powered pulsars. If the envelope consists of only heavy elements, on the other hand, the thickness is greater but increases less rapidly than what a light element envelope has. For such a heavy element envelope, the gamma-ray luminosity decreases relatively rapidly, forming the upper bound of the observed distribution. Th...

Hirotani, Kouichi

2013-01-01

305

Cosmological simulations of black hole growth: AGN luminosities and downsizing  

CERN Document Server

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...

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

2013-01-01

306

Probing the Low-Luminosity XLF in Normal Elliptical Galaxies  

CERN Document Server

We present the first low luminosity (LX > 5 - 10 1036 erg s-1) X-ray luminosity functions (XLFs) of low-mass X-ray binaries (LMXBs) determined for two typical old elliptical galaxies, NGC 3379 and NGC 4278. Because both galaxies contain little diffuse emission from hot ISM and no recent significant star formation (hence no high-mass X-ray binary contamination), they provide two of the best homogeneous sample of LMXBs. With 110 and 140 ks Chandra ACIS S3 exposures, we detect 59 and 112 LMXBs within the D25 ellipse of NGC 3379 and NGC 4278, respectively. The resulting XLFs are well represented by a single power-law with a slope (in a differential form) of 1.9 0.1. In NGC 4278, we can exclude the break at LX ~ 5 x 1037 erg s-1 that was recently suggested to be a general feature of LMXB XLFs. In NGC 3379 instead we find a localized excess over the power law XLF at ~4 x 1037 erg s-1, but with a marginal significance of ~1.6s. Because of the small number of luminous sources, we cannot constrain the high luminosity ...

Kim, D W; Kalogera, V; King, A R; Pellegrini, S; Trinchieri, G; Zepf, S E; Zezas, A L; Angelini, L; Davies, R L; Gallagher, J S

2006-01-01

307

The GRB variability/peak luminosity correlation: new results  

International Nuclear Information System (INIS)

We test the correlation between time variability and isotropic-equivalent peak luminosity found by Reichart et al. (ApJ, 552 (2001) 57) using a set of 26 Gamma-Ray Bursts (GRBs) with known redshift. We confirm the correlation, thought with a larger spread around the best-fit power-law obtained by Reichart et al. which in turn does not provide an acceptable description any longer. In addiction, we find no evidence for correlation between variability and beaming-corrected peak luminosity for a subset of 14 GRBs whose beaming angles have been taken from Ghirlanda et al. (ApJ, 616 (2004) 331). Finally, we investigate the possible connection for some GRBs between the location in the variability/peak luminosity space and some afterglow properties, such as the detectability in the optical band, by adding some GRBs whose redshifts, unknown from direct measurements, have been derived assuming the Amati at al. (AeA, 390 (2002) 81) relationship

308

Gamma-ray luminosity function of BL Lac objects  

Science.gov (United States)

The gamma-ray luminosity function (GLF) of BL Lac objects is constructed by using a sample of BL Lac objects with redshifts selected from the Second LAT AGN catalog. The GLFs of BL Lacs in the frame of the pure density evolution (PDE), the pure luminosity evolution (PLE), and the luminosity-dependent density (LDDE) models are determined by using the Markov Chain Monte Carlo (MCMC) technique, respectively. Our results suggest that the PDE model can give best description for BL Lac GLF based on the combination of constraints of model parameters and good fits to the observed data of Fermi-Large Area Telescope (LAT) BL Lacs, but other two models (PLE and LDDE) cannot be excluded. Based on our constructed GLFs, the contribution to the extragalactic diffuse gamma-ray background (EGRB) from BL Lacs is estimated, and ˜1-5 per cent of the EGRB in the 0.1-100 GeV band is found to come from unresolved BL Lacs (including the cascade emission). In addition, it is found that the BL Lac GLF is very different from flat spectrum radio quasar GLF and then the contribution of blazars to the EGRB should be estimated separately.

Zeng, Houdun; Yan, Dahai; Zhang, Li

2014-06-01

309

Total Infrared Luminosity Estimation of Resolved and Unresolved Galaxies  

CERN Document Server

The total infrared (TIR) luminosity from galaxies can be used to examine both star formation and dust physics. We provide here new relations to estimate the TIR luminosity from various Spitzer bands, in particular from the 8 micron and 24 micron bands. To do so, we use 45" subregions within a subsample of nearby face-on spiral galaxies from the Spitzer Infrared Nearby Galaxies Survey (SINGS) that have known oxygen abundances as well as integrated galaxy data from the SINGS, the Local Volume Legacy Survey (LVL) and Engelbracht et al. (2008) samples. Taking into account the oxygen abundances of the subregions, the star formation rate intensity, and the relative emission of the polycyclic aromatic hydrocarbons at 8 micron, the warm dust at 24 micron and the cold dust at 70 micron and 160 micron we derive new relations to estimate the TIR luminosity from just one or two of the Spitzer bands. We also show that the metallicity and the star formation intensity must be taken into account when estimating the TIR lumin...

Boquien, M; Calzetti, D; Dale, D; Engelbracht, C; Kennicutt, R; Lee, J C; van Zee, L; Moustakas, J

2010-01-01

310

Tidal dwarf galaxies and the luminosity-metallicity relation .  

Science.gov (United States)

We present a recalibration of the luminosity-metallicity relation for gas-rich, star-forming dwarfs to magnitudes as faint as M_R˜ -13. We use the \\citet{Dopita2013} metallicity calibrations to calibrate the relation for all of the data in this analysis. Metal-rich dwarfs classified as tidal dwarf galaxy (TDG) candidates in the literature are typically of metallicity 12 + log(O/H) = 8.70 ± 0.05, while SDSS dwarfs fainter than M_R = -16 have a mean metallicity of 12 + log(O/H) = 8.28 ± 0.10, regardless of their luminosity. Our hydrodynamical simuations predict that TDGs should have metallicities elevated above the normal luminosity-metallicity relation. Metallicity can therefore be a useful diagnostic for identifying TDG candidate populations in the absence of tidal tails. At magnitudes brighter than M_R˜ -16 our sample of 53 star-forming galaxies in 9 HI gas-rich groups is consistent with the normal relation defined by the SDSS sample. At fainter magnitudes there is an increase in dispersion in metallicity of our sample. In our sample we identify three (16% of dwarfs) strong TDG candidates (12 + log(O/H) > 8.6), and four (21%) very metal poor dwarfs (12 + log(O/H) < 8.0), which are likely gas-rich dwarfs with recently ignited star formation. Further details of this analysis are available in Sweet et al. (2013, ApJ submitted).

Sweet, S. M.; Drinkwater, M. J.; Meurer, G.; Bekki, K.; Dopita, M. A.; Kilborn, V.; Nicholls, D.

311

The Black Hole Mass - Galaxy Luminosity Relationship for SDSS Quasars  

CERN Document Server

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...

Salviander, S; Bonning, E W

2014-01-01

312

ALFA: Absolute Luminosity For ATLAS - Development of a scintillating fibre tracker to determine the absolute LHC luminosity at ATLAS  

International Nuclear Information System (INIS)

The ATLAS collaboration will determine the absolute luminosity of the CERN LHC at Interaction Point 1 by measuring the trajectory of protons elastically scattered at very small angles (?rad). A scintillating fibre tracker system called ALFA (Absolute Luminosity For ATLAS) is proposed for this measurement. Detector modules will be placed above and below the LHC beam axis in roman pot units at a distance of 240 m on each side of the ATLAS interaction point. They allow the detectors to approach the beam axis to millimeter distance. Overlap detectors also based on the scintillating fibre technology, will measure the precise relative position of the two detector modules. Results obtained during beam tests at DESY and at CERN validate the detectors design and demonstrate the achievable resolution. We report about preliminary results obtained with a full-scale prototype with final readout electronics in 2008.

313

Constraining the luminosity function of faint undetected i-dropout galaxies  

Science.gov (United States)

We present a new technique to quantify the light contribution coming from the faint high-redshift (z ˜ 6) galaxies below the detection threshold of imaging data, set conventionally at S/N = 4.5. We illustrate the technique with an application to Hubble Space Telescope Advanced Camera for Surveys images in the F775W and F850LP filters of the Ultra Deep Field parallel field NICP12. The aim of this analysis is to extend by a few magnitudes the faint end of the luminosity function at z ˜ 6. After masking all the detected sources in the field, we apply a fast Fourier transform to obtain the spatial power spectrum of the background signal. The power spectrum permits us to separate the background noise signal, the residuals due to the data reduction of the wide field and the overall signal produced by faint galaxies. The ratio of the signal in the i775 and z850 bands is used to estimate the contribution of the faint i-dropout objects. We rely on extensive Monte Carlo simulations to characterize various sources of uncertainty and quantify the number of faint i-dropout galaxies in the field. The analysis allows us to put constraints on the luminosity function at z ˜ 6 down to z850 = 30 mag, 2.5 mag fainter than with standard techniques on the same data. The data are consistent with a faint-end slope of the luminosity function of ? = -1.9. Assuming a specific set of values for the clumping factor, escape fraction and spectral energy distribution, we find that the z ˜ 6 undetected galaxies down to z850 = 30 mag could have driven cosmic reionization.

Calvi, V.; Pizzella, A.; Stiavelli, M.; Morelli, L.; Corsini, E. M.; Dalla Bontà, E.; Bradley, L.; Koekemoer, A. M.

2013-07-01

314

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

Energy Technology Data Exchange (ETDEWEB)

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; L{sub int} {<=} 0.1 L{sub Sun }). The sources are identified using data from the Spitzer Space Telescope cataloged by Dunham et al. toward nearby (D < 400 pc) star-forming regions. Each object was observed in {sup 12}CO and {sup 13}CO J = 2 {yields} 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.

Schwarz, Kamber R.; Shirley, Yancy L. [Steward Observatory, 933 N. Cherry Ave., Tucson, AZ 85721 (United States); Dunham, Michael M. [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

2012-10-01

315

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Alemany, R. (Inst. de Fisica d' Altes Energies, Univ. Autonoma de Barcelona, Bellaterra (Spain)); Fernandez, E. (Inst. de Fisica d' Altes Energies, Univ. Autonoma de Barcelona, Bellaterra (Spain)); Martinez, M. (Inst. de Fisica d' Altes Energies, Univ. Autonoma de Barcelona, Bellaterra (Spain)); Mato, P. (Inst. de Fisica d' Altes Energies, Univ. Autonoma de Barcelona, Bellaterra (Spain)); Perlas, J.A. (Inst. de Fisica d' Altes Energies, Univ. Autonoma de Barcelona, Bellaterra (Spain)); Rothberg, J. (Washington Univ., Seattle, WA (United States))

1993-06-20

316

On the universality of the initial luminosity function of open star clusters  

International Nuclear Information System (INIS)

The hypothesis on the universality of the initial luminosity function of open star clusters is discussed. Comparison of luminosity functions of 26 star clusters by the statistical criterion of Pearson and Kolmogorov shows mainly random differences for young and intermediate-age clusters. The results do not contradict the hypothesis of universality of the initial luminosity function of open clusters

317

The correlation of mass outflow velocity and luminosity for Mira variables  

International Nuclear Information System (INIS)

The terminal expansion velocities of circumstellar shells surrounding Mira variables, as deduced by other authors from radio observations of SiO, CO, and OH, are correlated with the mean bolometric luminosities of the parent stars. We find that the greater the photon output of a star the greater is the expansion velocity of its shell. The final gas velocities range from 3 km s-1 up to 22 km s-1 over a luminosity factor of 4. We presume that the purely gaseous steady-state outflow in the circumstellar regions close to the parent star is governed by the subsonic stellar wind function. At roughly 2R/sub asterisk/ the temperature becomes cool enough so that grains begin to form out of the heavy-element constituents of the gas. They grow rapidly, and stellar radiation pressure increasingly accelerates the grains relative to the ambient gas. The interaction of grains and gas serves to decelerate the grains and accelerate the gas. At several stellar radii the two components converge on their separate terminal velocities, with the gas moving more slowly than the grains. Together, the observational data and the hydrodynamic equations demand that the most luminous Miras in our sample produce somewhat bigger grains (typical radii approx.6--7 x 10-6 cm) than do the least luminous Miras

318

PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES  

International Nuclear Information System (INIS)

We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (Mr r –2 and 1% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case, the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r50) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M* ? 5 × 1011 M? and M* ? 1012 M? are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massion in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model

319

"Close galaxy pairs at z = 3: A challenge to UV luminosity abundance matching  

CERN Document Server

We use a sample of z~3 Lyman Break Galaxies (LBGs) to examine close pair clustering statistics in comparison to LCDM-based models of structure formation. Samples are selected by matching the LBG number density and by matching the observed LBG 3-D correlation function of LBGs over the two-halo term region. We show that UV-luminosity abundance matching cannot reproduce the observed data, but if subhalos are chosen to reproduce the observed clustering of LBGs we are able to reproduce the observed LBG pair fraction, (Nc), defined as the average number of companions per galaxy. This model suggests an over abundance of LBGs by a factor of ~5 over those observed, suggesting that only 1 in 5 halos above a fixed mass hosts a galaxy with LBG-like UV luminosity detectable via LBG selection techniques. We find a total observable close pair fraction of 23 \\pm 0.6% (17.7 \\pm 0.5%) using a prototypical cylinder radius in our overdense fiducial model and 8.3 \\pm 0.5% (5.6 \\pm 0.2%) in an abundance matched model (impurity cor...

Berrier, Joel

2012-01-01

320

Calibrating the Luminosity of Carbon Stars: An Archival Study of Galaxies in the Nearby Universe  

Science.gov (United States)

Intermediate age stellar populations dominate the light from high-redshift galaxies. Many of the stars in this age range end their lives as carbon-rich asymptotic giant branch stars {carbon stars}, a luminous but poorly constrained stage of stellar evolution. Population synthesis codes currently depend on models of carbon star evolution, which have been calibrated over a limited range of parameters. Carbon stars may account for up to 40% of the bolometric luminosity in high-redshift galaxies and recent studies have shown that the uncertainty in the contribution of carbon stars to integrated galaxy light can cause galactic mass and age estimates to change by a factor of 2. Here we propose to significantly improve this calibration over a much larger range of galactic environments by performing an archival HST study of the resolved carbon star populations throughout the nearby Universe {within 4 Mpc}. Carbon stars are relatively easily identified in color-magnitude diagrams, allowing us to determine their luminosity and relative number densities. We have identified a sample of 40 galaxies with sufficiently deep HST photometry to determine accurate star formation histories and compare the properties of the carbon stars to the properties {e.g., age, metallicity, star formation rate} of the underlying populations. Our study will result in an empirical calibration of carbon stars that can be used to place much needed constraints on stellar evolution models and thereby improve our understanding of galaxy evolution.

Grocholski, Aaron

2013-10-01

 
 
 
 
321

LUMINOSITIES OF BARRED AND UNBARRED S0 GALAXIES  

Energy Technology Data Exchange (ETDEWEB)

Lenticular galaxies with M{sub B} < -21.5 are almost exclusively unbarred, whereas both barred and unbarred objects occur at fainter luminosity levels. This effect is observed both for objects classified in blue light, and for those that were classified in the infrared. This result suggests that the most luminous (massive) S0 galaxies find it difficult to form bars. As a result, the mean luminosity of unbarred lenticular galaxies in both B and IR light is observed to be {approx}0.4 mag brighter than that of barred lenticulars. A small contribution to the observed luminosity difference that is found between SA0 and SB0 galaxies may also be due to the fact that there is an asymmetry between the effects of small classification errors on SA0 and SB0 galaxies. An elliptical (E) galaxy might be misclassified as a lenticular (S0) or an S0 as an E. However, an E will never be misclassified as an SB0, nor will an SB0 ever be called an E. This asymmetry is important because E galaxies are typically twice as luminous as S0 galaxies. The present results suggest that the evolution of luminous lenticular galaxies may be closely linked to that of elliptical galaxies, whereas fainter lenticulars might be more closely associated with ram-pressure stripped spiral galaxies. Finally, it is pointed out that fine details of the galaxy formation process might account for some of the differences between the classifications of the same galaxy by individual competent morphologists.

Van den Bergh, Sidney, E-mail: sidney.vandenbergh@nrc.gc.ca [Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

2012-07-20

322

Cosmological variation of G and the solar Luminosity  

International Nuclear Information System (INIS)

We reexamine Teller's analysis of the effects of a varying gravitational constant G on the past solar luminosity. We show that if Newtonian graviation is viewed as a nonrelativistic limit of Einstein's theory, there exists (1) a constraint between G and the total mass M of the Sun and (2) a change in the radiative energy density-temperature relation, which were not included in Teller's analysis and which change his result from Lapprox.G7 (found to be unacceptable) to Lapprox.constant, independently of how G might vary with time

323

Prospects for physics at high luminosity with CMS  

Directory of Open Access Journals (Sweden)

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.

Varela João

2013-05-01

324

The X-Ray Luminosity Function of Active Galactic Nuclei  

CERN Document Server

We derive an X-ray luminosity function for active galactic nuclei (AGN) that accounts for the X-ray source counts in the 0.5-2.0 and 2-10 keV energy ranges, the redshift distribution of AGNs in the ROSAT Deep Survey (RDS), as well as the X-ray background (XRB) from 1-10 keV. We emphasize the role of X-ray absorption, which has a large effect on the faint end of the 2-10 keV source counts, as well as on the integrated X-ray background.

Schmidt, M; Hasinger, G; Trümper, J E; Zamorani, G

1999-01-01

325

Sky luminosity for Rio de Janeiro City - Brazil  

International Nuclear Information System (INIS)

This paper presents sky luminosity data for Rio de Janeiro City, useful to be used in daylighting design in architecture. The data are presented as monthly graphics that correlate sunshine-hours with the frequency of occurrence during the day of a specific type of sky, that would present one of five defined characteristics (among clear and overcast sky). These results were derived from the knowledge of daily solar radiation and sunshine-hours data, for every day for a twelve year period. (author). 10 refs, 13 figs, 16 tabs

326

The Luminosity Function for L > L* Galaxies at z > 3  

CERN Document Server

Through use of multiband (U, B, R, I) photometry we have isolated high redshift (3.0 L* luminosity function for z = 3-5 galaxies obtained by a photometric redshift analysis of the Hubble Deep Field (HDF) by Gwyn & Hartwick (1996). Our results at R ~ 23 are more consistent with the photometric redshift analysis of the faint HDF galaxies by Sawicki & Yee (1996), but our present upper limits at the brightest magnitudes (R < 21.5, M(R) < -24) allow more generous volume densities of these super-L* galaxies.

Bershady, M A; Koo, D C; Kron, Richard G; Munn, J A; Bershady, Matthew A.; Majewski, Steven R.; Koo, David C.; Kron, Richard G.; Munn, Jeffrey A.

1997-01-01

327

Radiation environment and shielding for a high luminosity collider detector  

Energy Technology Data Exchange (ETDEWEB)

Detectors now under design for use in the proposed high energy high luminosity colliders must deal with unprecedented radiation levels. We have performed a comprehensive study for the GEM detector at the SSC to determine the best way to shield critical detector components from excessive radiation, with special attention paid to the low energy neutrons and photons. We have used several detailed Monte-Carlo simulations to calculate the particle fluxes in the detector. We describe these methods and demonstrate that two orders of magnitude reduction in the neutron and photon fluxes can be obtained with appropriate shielding of critical forward regions such as the low beta quadrupoles and the forward calorimeter.

Diwan, M.V.; Fisyak, Y.; Mokhov, N.V. [Superconducting Super Collider Lab., Dallas, TX (United States)] [and others

1995-12-01

328

Radiation environment and shielding for a high luminosity collider detector  

International Nuclear Information System (INIS)

Detectors now under design for use in the proposed high energy high luminosity colliders must deal with unprecedented radiation levels. We have performed a comprehensive study for the GEM detector at the SSC to determine the best way to shield critical detector components from excessive radiation, with special attention paid to the low energy neutrons and photons. We have used several detailed Monte-Carlo simulations to calculate the particle fluxes in the detector. We describe these methods and demonstrate that two orders of magnitude reduction in the neutron and photon fluxes can be obtained with appropriate shielding of critical forward regions such as the low beta quadrupoles and the forward calorimeter

329

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

DEFF Research Database (Denmark)

We investigate the relationship between black hole mass and bulge luminosity for 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 \\propto L^{1.0+/-0.1} relationship that has been fit to nearby quiescent galaxies with dynamical black hole mass measurements. This is somewhat perplexing, as the AGN black hole masses include an overall scaling factor that brings the AGN M_BH-sigma 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.

Bentz, Misty C.; Peterson, Bradley M.

2008-01-01

330

Luminosities and mass-loss rates of SMC and LMC AGB stars and red supergiants  

Science.gov (United States)

Context: Mass loss is one of the fundamental properties of Asymptotic Giant Branch (AGB) stars, and through the enrichment of the interstellar medium, AGB stars are key players in the life cycle of dust and gas in the universe. However, a quantitative understanding of the mass-loss process is still largely lacking, particularly its dependence on metallicity. Aims: To investigate the relation between mass loss, luminosity and pulsation period for a large sample of evolved stars in the Small and Large Magellanic Cloud. Methods: Dust radiative transfer models are presented for 101 carbon stars and 86 oxygen-rich evolved stars in the Magellanic Clouds for which 5-35 ?m Spitzer IRS spectra are available. The spectra are complemented with available optical and infrared photometry to construct the spectral energy distribution. A minimisation procedure is used to fit luminosity, mass-loss rate and dust temperature at the inner radius. Different effective temperatures and dust content are also considered. Periods from the literature and from new OGLE-III data are compiled and derived. Results: We derive (dust) mass-loss rates and luminosities for the entire sample. Based on luminosities, periods and amplitudes and colours, the O-rich stars are classified as foreground objects, AGB stars and Red Super Giants. For the O-rich stars silicates based on laboratory optical constants are compared to “astronomical silicates”. Overall, the grain type by Volk & Kwok (1988, ApJ, 331, 435) fits the data best. However, the fit based on laboratory optical constants for the grains can be improved by abandoning the small-particle limit. The influence of grain size, core-mantle grains and porosity are explored. A computationally convenient method that seems to describe the observed properties in the 10 ?m window are a distribution of hollow spheres with a large vacuum fraction (typically 70%), and grain size of about 1 ?m. Relations between mass-loss rates and luminosity and pulsation period are presented and compared to the predictions of evolutionary models, those by Vassiliadis & Wood (1993, ApJ, 413, 641) and their adopted mass-loss recipe, and those based on a Reimers mass-loss law with a scaling of a factor of five. The Vassiliadis & Wood models describe the data better, although there are also some deficiencies, in particular to the maximum adopted mass-loss rate. The derived mass-loss rates are compared to predictions by dynamical wind models and appear consistent with them at a level of a factor 2-4. A better understanding requires the determination of the expansion velocity from future observations from ALMA. The OGLE-III data reveal an O-rich star in the SMC with a period of 1749 days. Its absolute magnitude of M_bol= -8.0 makes it a good candidate for a super-AGB star. Complete Figs. 1-3 and 5-7 are only available in electronic form at http://www.aanda.org Complete Tables 1-4 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/506/1277

Groenewegen, M. A. T.; Sloan, G. C.; Soszy?ski, I.; Petersen, E. A.

2009-11-01

331

The z=5 Quasar Luminosity Function from SDSS Stripe 82  

CERN Document Server

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

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

332

Differential Density Statistics of Galaxy Distribution and the Luminosity Function  

CERN Document Server

This paper uses data obtained from the galaxy luminosity function (LF) to calculate two types of radial number densities statistics of the galaxy distribution as discussed in Ribeiro (2005), namely the differential density $\\gamma$ and the integral differential density $\\gamma^\\ast$. By applying the theory advanced by Ribeiro and Stoeger (2003), which connects the relativistic cosmology number counts with the astronomically derived LF, the differential number counts $dN/dz$ are extracted from the LF and used to calculate both $\\gamma$ and $\\gamma^\\ast$ with various cosmological distance definitions, namely the area distance, luminosity distance, galaxy area distance and redshift distance. LF data are taken from the CNOC2 galaxy redshift survey and $\\gamma$ and $\\gamma^\\ast$ are calculated for two cosmological models: Einstein-de Sitter and an $\\Omega_{m_0}=0.3$, $\\Omega_{\\Lambda_0}=0.7$ standard cosmology. The results confirm the strong dependency of both statistics on the distance definition, as predicted in...

Albani, V V L; Ribeiro, M B; Stöger, W R; Albani, Vinicius V. L.; Iribarrem, Alvaro S.; Ribeiro, Marcelo B.; Stoeger, William R.

2006-01-01

333

The Variation of the Galaxy Luminosity Function with Group Properties  

CERN Document Server

We explore the shape of the galaxy luminosity function (LF) in groups of different mass by creating composite LFs over large numbers of groups. Following previous work using total group luminosity as the mass indicator, here we split our groups by multiplicity and by estimated virial (group halo) mass, and consider red (passive) and blue (star forming) galaxies separately. In addition we utilise two different group catalogues (2PIGG and Yang et al.) in order to ascertain the impact of the specific grouping algorithm and further investigate the environmental effects via variations in the LF with position in groups. Our main results are that LFs show a steepening faint end for early type galaxies as a function of group mass/ multiplicity, with a much suppressed trend (evident only in high mass groups) for late type galaxies. Variations between LFs as a function of group mass are robust irrespective of which grouping catalogue is used, and broadly speaking what method for determining group `mass' is used. We fin...

Robotham, Aaron; de Propris, Roberto

2010-01-01

334

The Luminosity Function of the Milky Way Satellites  

CERN Document Server

We quantify the algorithmic detectability of stellar Milky Way satellites in data release 5 (DR5) of the Sloan Digital Sky Survey (SDSS), and use this to estimate the luminosity function of faint satellite galaxies in our halo. We develop a satellite detection algorithm based on the convolution of the DR5 star catalog with a kernel of zero net flux that is the difference of a narrow positive Gaussian and a much wider negative Gaussian, which removes the background star-count level. This permits us to assess the significance of any (positive) detection in terms of deviations of this map. The efficiency of this algorithm is tested by computing the recovery rate of a large set of mock objects added to SDSS DR5 as a function of their luminosity, size and distance from the Sun. Most of the recent Milky Way satellite discoveries, made by SDSS, are shown to lie very close to the survey's detection limits. Calculating the maximum accessible volume $V_{max}$ for all faint detected objects makes it possible for the fir...

Koposov, S; Evans, N W; Hewett, P C; Irwin, M J; Gilmore, G; Zucker, D B; Rix, H -W; Fellhauer, M; Bell, E F; Glushkova, E V

2007-01-01

335

An Upgraded ATLAS Central Trigger for 2014 Luminosities  

CERN Document Server

During 2011, the LHC reached instantaneous luminosities of 4*10^33 cm-2*s-1 and produced events with up to 24 interactions per colliding proton bunch. This places stringent operational and physical requirements on the ATLAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of ~400Hz and, at the same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and a decision latency of less than 2.5us. It is primarily composed of the Calorimeter Trigger, Muon Trigger, and the Central Trigger Processor which are implemented in custom built VME electronics. The Central Trigger Processor collects trigger information from all Level-1 systems and produces a Level-1 trigger decision that initiates the readout of all ATLAS detectors. In 2014, the LHC will run at a center of mass energy of 14 TeV, compared to the current 8 TeV, and the luminosity will exceed 10^34 cm^-2*s^-1. With higher ...

Anders, G; The ATLAS collaboration; Bertelsen, H; Childers, T; Dam, M; Dobson, E; Ellis, N; Farthouat, P; Gabaldon, C; Gorini, B; Haas, S; Kaneda, M; Maettig, S; Messina, A; Pauly, T; Pöttgen, R; Spiwoks, R; Wengler, T; Xella, S

2012-01-01

336

An Upgraded ATLAS Central Trigger for 2014 LHC Luminosities  

CERN Document Server

During 2011, the LHC reached instantaneous luminosities of 4*10^33 cm-2*s-1 and produced events with up to 24 interactions per colliding proton bunch. Thisplaces stringent operational and physical requirements on the ATLAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of ~400Hz and, atthe same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and adecision latency of less than 2.5us. It is primarily composed of the Calorimeter Trigger, Muon Trigger, and the Central Trigger Processor which are implemented in custom builtVME electronics. The Central Trigger Processor collects trigger information from all Level-1 systems and produces a Level-1 trigger decision that initiates the readout of all ATLAS subdetectors. In 2014, the LHC will run at a center of mass energy of 14 TeV, compared to the current 8 TeV, and the luminosity will exceed 10^34 cm^-2*s^-1. With higher l...

Kaneda, M; The ATLAS collaboration

2012-01-01

337

An Upgraded ATLAS Central Trigger for 2014 LHC Luminosities  

CERN Document Server

During 2011, the LHC reached instantaneous luminosities of 4*10^33 cm^-1*s^-1 and produced events with up to 24 interactions per colliding proton bunch. This places stringent operational and physical requirements on the ATLAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of ~400Hz and, at the same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and a decision latency of less than 2.5us. It is primarily composed of the Calorimeter Trigger, Muon Trigger, and the Central Trigger Processor which are implemented in custom built VME electronics. The Central Trigger Processor collects trigger information from all Level-1 systems and produces a Level-1 trigger decision that initiates the readout of all ATLAS sub-detectors. In 2014, the LHC will run at a center of mass energy of 14 TeV, compared to the current 8 TeV, and the luminosity will exceed 10^34 cm^-1*s^-1. With h...

Kaneda, M; The ATLAS collaboration

2012-01-01

338

Topological and Central Trigger Processor for 2014 LHC luminosities  

CERN Document Server

The ATLAS experiment is located at the European Center for Nu- clear Research (CERN) in Switzerland. It is designed to observe phe- nomena that involve highly massive particles produced in the collisions at the Large Hadron Collider (LHC): the world’s largest and highest-energy particle accelerator. Event triggering and Data Acquisition is one of the extraordinary challenges faced by the detectors at the high luminosity LHC collider. During 2011, the LHC reached instantaneous luminosities of 4×10^33 cm?1 s?1 and produced events with up to 24 interactions per colliding proton bunch. This places stringent operational and physical requirements on the AT- LAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of 400Hz and, at the same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and decision latency of less than 2.5?s. It is primarily composed of the Calorimete...

Simioni, E; The ATLAS collaboration; Bauss, B; Berge, D; B\\"{u}scher, V; Childers, T; Degele, R; Dobson, E; Ebling, A; Ellis, N; Farthouat, P; Gabaldon, C; Gorini, B; Haas, S; Ji, W; Kaneda, M; M\\"{a}ttig, S; Messina, A; Meyer, C; Moritz, S; Pauly, T; Pottgen, R; Sch\\"{a}fer, U; Spiwoks, R; Tapprogge, S; Wengler, T; Wenzel, V

2012-01-01

339

Topological and Central Trigger Processor for 2014 LHC luminosities  

CERN Document Server

The ATLAS experiment is located at the European Center for Nuclear Research (CERN) in Switzerland. It is designed to observe phenomena that involve highly massive particles produced in the collisions at the Large Hadron Collider (LHC): the world’s largest and highest-energy particle accelerator. Event triggering and Data Acquisition is one of the extraordinary challenges faced by the detectors at the high luminosity LHC collider. During 2011, the LHC reached instantaneous luminosities of 4 10^33 cm?1 s?1 and produced events with up to 24 interactions per colliding proton bunch. This places stringent operational and physical requirements on the ATLAS Trigger in order to reduce the 40MHz collision rate to a manageable event storage rate of 400Hz and, at the same time, selecting those events considered interesting. The Level-1 Trigger is the first rate-reducing step in the ATLAS Trigger, with an output rate of 75kHz and decision latency of less than 2.5 micro seconds. It is primarily composed of the Calori...

Simioni, E; The ATLAS collaboration; Bauss, B; Berge, D; Buscher, V; Childers, T; Degele, R; Dobson, E; Ebling, A; Ellis, N; Farthouat, P; Gabaldon, C; Gorini, B; Haas, S; Ji, W; Kaneda, M; Mattig, S; Messina, A; Meyer, C; Moritz, S; Pauly, T; Pottgen, R; Schafer, U; Spiwoks, R; Tapprogge, S; Wengler, T; Wenzel, V

2012-01-01

340

An upgraded ATLAS Central Trigger for post-2014 LHC luminosities  

CERN Document Server

During 2011, the LHC reached instantaneous luminosities of 6.7 · 10^33 cm?2s?1 and produced events with up to 40 interactions per colliding proton bunch. This places stringent operational and physical requirements on the ATLAS trigger in order to reduce the 40 MHz collision rate to a manageable event storage rate of 400 Hz without discarding those events considered interesting. The Level-1 trigger is the first rate-reducing step in the ATLAS trigger, with an output rate of 75 kHz and a decision latency of less than 2.5 ? s. It is primarily composed of the Calorimeter Trigger, Muon Trigger, and the Central Trigger Processor which are implemented in custom built VME electronics. The Central Trigger Processor collects trigger information from all Level-1 systems and produces a Level-1 trigger decision that initiates the readout of all ATLAS detectors. After 2014, the LHC will run at a center of mass energy of up to 14 TeV, compared to the current 8 TeV, and the luminosity will exceed 10^34 cm?2s?1. Wit...

Anders, G; The ATLAS collaboration; Bertelsen, H; Childers, T; Dam, M; Dobson, E; Ellis, N; Farthouat, P; Gabaldon, C; Gorini, B; Haas, S; Kaneda, M; Maettig, S; Messina, A; Ohm, C; Pauly, T; Poettgen, R; Spiwoks, R; Wengler, T; Xella, S

2012-01-01

 
 
 
 
341

Radio Variability Survey of Very Low Luminosity Protostars  

CERN Document Server

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 interstella...

Choi, Minho; Kang, Miju

2014-01-01

342

Progress toward a high-energy, high luminosity ?+?- collider  

International Nuclear Information System (INIS)

In the past two years, considerable progress has been made in development of the ?+?- collider concept. This collider concept could permit exploration of elementary particle physics at energy frontiers beyond the reach of currently existing and proposed electron and hadron colliders. As a benchmark prototype, we present a candidate design for a high-energy high-luminosity ?+?- collider, with Ecm = 4 TeV, L = 3 x 1034 cm-2s-1, based on existing technical capabilities. The design uses a rapid-cycling medium-energy proton synchrotron, producing proton beam pulses which are focused onto two ?-producing targets, with two ?-decay transport lines producing ?+'s and ?-'s. the ?'s are collected, rf-rotated, cooled and compressed into a recirculating linac for acceleration, and then transferred into a storage ring collider. The keys to high luminosity are maximal ? collection and cooling, and innovations with these goals are presented. Possible variations and improvements are discussed. Recent progress in collider concept development is summarized, and future plans for collider development are discussed

343

The dynamical state of galaxy groups and their luminosity content  

CERN Document Server

We analyse the dependence of the luminosity function of galaxies in groups (LF) on group dynamical state. We use the Gaussianity of the velocity distribution of galaxy members as a measurement of the dynamical equilibrium of groups identified in the SDSS Data Release 7 by Zandivarez & Martinez. We apply the Anderson-Darling goodness-of-fit test to distinguish between groups according to whether they have Gaussian or Non-Gaussian velocity distributions, i.e., whether they are relaxed or not. For these two subsamples, we compute the $^{0.1}r-$band LF as a function of group virial mass and group total luminosity. For massive groups, ${\\mathcal M}>5 \\times 10^{13} \\ M_{\\odot} \\ h^{-1}$, we find statistically significant differences between the LF of the two subsamples: the LF of groups that have Gaussian velocity distributions have a brighter characteristic absolute magnitude ($\\sim0.3$ mag) and a steeper faint end slope ($\\sim0.25$). We detect a similar effect when comparing the LF of bright ($M^{group}_{^{0...

Martinez, Hector J

2011-01-01

344

Colorblind vision; luminosity losses in the spectrum for dichromats.  

Science.gov (United States)

1. Measurements have been made of the dark-adapted foveal threshold of normal and colorblind persons in five parts of the spectrum using a 1 degrees circular test field. 2. Compared to normals, protanopes (red-blinds) show an elevation of the threshold which increases slowly from blue to yellow and rises rapidly thereafter until in the red the threshold is more than ten times as high as normal. Deuteranopes (green-blinds) do not show so high an elevation, their maximum in the green being only about 70 per cent above normal. 3. These threshold elevations correspond to luminosity losses in the spectrum. For the protanope the total loss in the spectrum is nearly one-half of the normal luminosity; for the deuteranope it is nearly two-fifths of normal. 4. Such losses support the idea that colorblindness corresponds to the loss of one of the three receptor systems usually postulated to account for normal color vision. However, the color sensations reported by colorblind persons, especially monocular colorblinds, do not support the idea of a lost or inactivated receptor system. A fresh explanation for colorblindness is called for to reconcile these conflicting kinds of evidence. PMID:18896937

HECHT, S; HSIA, Y

1947-11-20

345

The Luminosity Profile and Structural Parameters of the Andromeda Galaxy  

CERN Document Server

We have constructed an extended composite luminosity profile for the Andromeda galaxy, M31, and have decomposed it into three basic luminous structural components: a bulge, a disk and a halo. The dust-free Spitzer/IRAC imaging and extended spatial coverage of ground-based optical imaging and deep star counts allow us to map M31's structure from its center to 22 kpc along the major axis. We apply different decomposition methods for the 1D luminosity profiles and 2D images. These include non-linear least-squares and Bayesian Monte-Carlo Markov-chain analyses. The basic photometric model for M31 has a Sersic bulge with shape index n = 2.2 +/- 0.3 and effective radius R_e = 1.0 +/- 0.2 kpc, a dust-free exponential disk of scale length R_d = 5.3 +/- 0.5 kpc; the parameter errors reflect the range between various decomposition methods. The bulge parameter, n, is rather insensitive to bandpass effects and its value suggests a first rapid formation via mergers followed by secular growth from the disk. The M31 halo ha...

Courteau, Stephane; McDonald, Michael; Guhathakurta, Puragra; Gilbert, Karoline M; Zhu, Yucong; Beaton, Rachael Lynn; Majewski, Steven R

2011-01-01

346

An Upgraded ATLAS Central Trigger for 2015 LHC Luminosities  

CERN Document Server

The LHC collides protons at a rate of 40 MHz and each collision produces ?1.5~MB of data from the ATLAS detector. The ATLAS trigger system is implemented in three levels and selects only the most interesting collision events to reduce the event storage rate to about 400 Hz. The first level is implemented in custom electronics and reduces the input rate to ?75 kHz with a decision latency of ?2.5 us. It is also responsible for initiating the read-out of data from all the sub-detectors in ATLAS. Based primarily on information from calorimeters and muon trigger detectors, the Central Trigger Processor (CTP) produces the Level-­1 trigger decision. After a very successful first run, the LHC is now being upgraded to operate with increased luminosity and a center-of-mass energy of up to 14 TeV. To cope with the higher luminosities, the Level-1 trigger system will have to perform a more refined selection in order to not lose interesting physics data while keeping the total Level-1 rate below 100~kHz. In this pr...

Ohm, C; The ATLAS collaboration

2014-01-01

347

LHC Report: spring cleaning over, bunches of luminosity  

CERN Multimedia

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...

CERN Bulletin

2011-01-01

348

Relativistic Cosmology Number Densities and the Luminosity Function  

CERN Document Server

This paper studies the connection between the relativistic number density of galaxies down the past light cone in a Friedmann-Lemaitre-Robertson-Walker spacetime with non-vanishing cosmological constant and the galaxy luminosity function (LF) data. It extends the redshift range of previous results presented in Albani et al. (2007, arXiv:astro-ph/0611032) where the galaxy distribution was studied out to z=1. Observational inhomogeneities were detected at this range. This research also searches for LF evolution in the context of the framework advanced by Ribeiro and Stoeger (2003, arXiv:astro-ph/0304094), further developing the theory linking relativistic cosmology theory and LF data. Selection functions are obtained using the Schechter parameters and redshift parametrization of the galaxy luminosity functions obtained from an I-band selected dataset of the FORS Deep Field galaxy survey in the redshift range 0.5

Iribarrem, Alvaro S; Ribeiro, Marcelo B; Stoeger, William R

2012-01-01

349

High luminosity electron-hadron collider eRHIC  

Energy Technology Data Exchange (ETDEWEB)

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.

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

350

Detection of Radio Outbursts of Young Low-Luminosity Protostars  

Science.gov (United States)

Magnetosphere is an integral part of a star and plays important roles in the dynamics of ionized gas in and around the star.The magnetosphere manifests itself through powerful outbursts of energy such as radio and X-ray flares, and such magnetic activities start well before the onset of stable hydrogen burning. The magnetic fields of young stellar objects may be seeded by the interstellar magnetic fields in the natal cloud. However, the origin of stellar magnetic fields has been difficult to study because class 0 protostars are surrounded by opaque layers of gas that block the radio emission from the view of outside observers. Recently discovered very-low-luminosity protostars may have relatively transparent outer layers and present a new opportunity to directly observe the protostellar magnetic activities. We detected a radio outburst of a class 0 protostar in the Taurus star-forming region. The outburst timescale of 20 days is consistent with magnetic flares. Since this protostar is too young and small to develop an internal convective dynamo, the flare may be caused by the magnetic fields of interstellar origin. Such flares may be a dominant source of high-energy photons around these low-luminosity protostars.

Choi, Minho; Lee, J.; Kang, M.

2014-01-01

351

The RR Lyrae Period-Luminosity Relation. I. Theoretical Calibration  

CERN Document Server

We present a theoretical calibration of the RR Lyrae period-luminosity (PL) relation in the UBVRIJHK Johnsons-Cousins-Glass system. Our theoretical work is based on calculations of synthetic horizontal branches (HBs) for several different metallicities, fully taking into account evolutionary effects besides the effect of chemical composition. Extensive tabulations of our results are provided, including convenient analytical formulae for the calculation of the coefficients of the period-luminosity relation in the different passbands as a function of HB type. We also provide "average" PL relations in IJHK, for applications in cases where the HB type is not known a priori; as well as a new calibration of the M_V - [M/H] relation. These can be summarized as follows: M_I = +0.471 - 1.132 log P + 0.205 log Z, M_J = -0.141 - 1.773 log P + 0.190 log Z, M_H = -0.551 - 2.313 log P + 0.178 log Z, M_K = -0.597 - 2.353 log P + 0.175 log Z, and M_V = +2.288 + 0.882 log Z + 0.108 (log Z)^2.

Catelan, M

2004-01-01

352

Spectral-Luminosity relation within individual Fermi GRBs  

CERN Document Server

We study the spectra of all long Gamma Ray Bursts (GRBs) of known redshift detected by the Fermi satellite. Their fluxes and fluences are large enough to allow a time dependent study of their spectral characteristics in the 8 keV-1 MeV energy range. We find that the peak energy Ep of their EL(E) spectrum correlates with the luminosity in a remarkable tight way within individual bursts. This time resolved Ep-Liso correlation is very similar for all the considered bursts, and has a slope and normalisation similar to the analogous Ep-Liso correlation defined by the time integrated spectra of different bursts detected by several different satellites. For a few of the considered GRBs, we could also study the behaviour of the Ep-Liso correlation during the rising and decaying phases of individual pulses within each burst, finding no differences. Our results indicate the presence of a similar physical mechanism, operating for the duration of different GRBs, linking tightly the burst luminosity with the peak energy o...

Ghirlanda, G; Ghisellini, G

2009-01-01

353

A two-mode planetary nebula luminosity function  

CERN Document Server

We propose a new Planetary Nebula Luminosity Function (PNLF) that includes two populations in the distribution. Our PNLF is a direct extension of the canonical function proposed by Jacoby et al. (1987), in order to avoid problems related with the histogram construction, it is cast in terms of cumulative functions. We are interested in recovering the shape of the faint part of the PNLF in a consistent manner, for galaxies with and without a dip in their PN luminosity functions. The parameters for the two mode PNLF are obtained with a genetic algorithm, which obtains a best fit to the PNLF varying all of the parameters simultaneously in a broad parameter space. We explore a sample of 9 galaxies with various Hubble types and construct their PNLF. All of the irregular galaxies, except one, are found to be consistent with a two-mode population, while the situation is less clear for ellipticals and spirals.For the case of NGC\\, 6822, we show that the two-mode PNLF is consistent with previous studies of the star for...

Rodríguez-González, A; Esquivel, A; Raga, A C; Stasi?ska, G; Peña, M; Mayya, D

2014-01-01

354

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

355

Autofib Redshift survey; 1, evolution of the galaxy luminosity function  

CERN Document Server

We present a detailed determination of the restframe B-band galaxy luminosity function (LF) as a function of redshift and star formation activity from z=0 to z=0.75. The dataset used for this purpose is a combined sample of over 1700 redshifts spanning a wide range in apparent magnitude, 11.5luminosity galaxies. Furthermore, surface brig...

Ellis, Richard S; Broadhurst, T J; Heyl, J S; Ellis, Richard S; Colless, Matthew; Broadhurst, Tom; Heyl, Jeremy

1995-01-01

356

Optical variability properties of high luminosity AGN classes  

CERN Document Server

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...

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

2003-01-01

357

Determination of target thickness and luminosity from beam energy losses  

Science.gov (United States)

The repeated passage of a coasting ion beam of a storage ring through a thin target induces a shift in the revolution frequency due to the energy loss in the target. Since the frequency shift is proportional to the beam-target overlap, its measurement offers the possibility of determining the target thickness and hence the corresponding luminosity in an experiment. This effect has been investigated with an internal proton beam of energy 2.65 GeV at the COSY-Jülich accelerator using the ANKE spectrometer and a hydrogen cluster-jet target. Possible sources of error, especially those arising from the influence of residual gas in the ring, were carefully studied, resulting in an accuracy of better than 5%. The luminosity determined in this way was used, in conjunction with measurements in the ANKE forward detector, to determine the cross section for elastic proton-proton scattering. The result is compared to published data as well as to the predictions of a phase shift solution. The practicability and the limitations of the energy-loss method are discussed.

Stein, H. J.; Hartmann, M.; Keshelashvili, I.; Maeda, Y.; Wilkin, C.; Dymov, S.; Kacharava, A.; Khoukaz, A.; Lorentz, B.; Maier, R.; Mersmann, T.; Mikirtychiants, S.; Prasuhn, D.; Stassen, R.; Stockhorst, H.; Ströher, H.; Valdau, Yu.; Wüstner, P.

2008-05-01

358

Determination of target thickness and luminosity from beam energy losses  

CERN Document Server

The repeated passage of a coasting ion beam of a storage ring through a thin target induces a shift in the revolution frequency due to the energy loss in the target. Since the frequency shift is proportional to the beam-target overlap, its measurement offers the possibility of determining the target thickness and hence the corresponding luminosity in an experiment. This effect has been investigated with an internal proton beam of energy 2.65 GeV at the COSY-J\\"ulich accelerator using the ANKE spectrometer and a hydrogen cluster-jet target. Possible sources of error, especially those arising from the influence of residual gas in the ring, were carefully studied, resulting in a accuracy of better than 5%. The luminosity determined in this way was used, in conjunction with measurements in the ANKE forward detector, to determine the cross section for elastic proton-proton scattering. The result is compared to published data as well as to the predictions of a phase shift solution. The practicability and the limita...

Stein, H J; Keshelashvili, I; Maeda, Y; Wilkin, C; Dymov, S; Kacharava, A; Khoukaz, A; Lorentz, B; Maier, R; Mersmann, T; Mikirtychiants, S; Prasuhn, D; Stassen, R; Stockhorst, H; Ströher, H; Valdau, Yu; Wüstner, P

2008-01-01

359

Metallicity effects on synthetic Cepheid Period-Luminosity relations  

Science.gov (United States)

On the basis of new theoretical results (Bono, Marconi & Stellingwerf, 1998, hereafter BMS; Bono, Caputo, Castellani & Marconi, 1998, hereafter BCCM) useful predictions concerning the Period-Luminosity (PLR) and Period-Luminosity-Color (PLCR) relations both for optical and infrared magnitudes are presented. It is shown that, following the dependence of the instability strip on metallicity, there is a non negligible dependence of the PLRs and PLCRs on the metallicity of the pulsating stars, mainly for optical bands. In particular theoretical results predict a dependence of the PLR on metals which is reversed with respect to current empirical evaluations (see for instance Gould 1994, Sasselov et al. 1997, Kennicutt et al. 1998, hereafter K98). To give a possible explanation for this discrepancy the typical observational procedures used to estimate extragalactic distances through Cepheid PLRs are here tested, with the aim of disentangling, if possible, the reddening and metallicity effects. To this purpose, synthetic PLRs for different metallicities were produced and treated as typical observational samples.

Musella, I.

360

SDSS Galaxy Clustering: Luminosity & Color Dependence and Stochasticity  

CERN Document Server

Differences in clustering properties between galaxy subpopulations complicate the cosmological interpretation of the galaxy power spectrum, but can also provide insights about the physics underlying galaxy formation. To study the nature of this relative clustering, we perform a counts-in-cells analysis of galaxies in the Sloan Digital Sky Survey (SDSS) in which we measure the relative bias between pairs of galaxy subsamples of different luminosities and colors. We use a generalized chi-squared test to determine if the relative bias between each pair of subsamples is consistent with the simplest deterministic linear bias model, and we also use a maximum likelihood technique to further understand the nature of the relative bias between each pair. We find that the simple, deterministic model is a good fit for the luminosity-dependent bias on scales above about 5 Mpc/h, which is good news for using magnitude-limited surveys for cosmology. However, the color-dependent bias shows evidence for stochasticity and/or n...

Swanson, M E C; Blanton, M; Zehavi, I; Swanson, Molly E.C.; Tegmark, Max; Blanton, Michael; Zehavi, Idit

2007-01-01

 
 
 
 
361

Luminous Satellites II: Spatial Distribution, Luminosity Function and Cosmic Evolution  

CERN Document Server

We infer the normalization and the radial and angular distributions of the number density of satellites of massive galaxies ($\\log_{10}[M_{h}^*/M\\odot]>10.5$) between redshifts 0.1 and 0.8 as a function of host stellar mass, redshift, morphology and satellite luminosity. Exploiting the depth and resolution of the COSMOS HST images, we detect satellites up to eight magnitudes fainter than the host galaxies and as close as 0.3 (1.4) arcseconds (kpc). Describing the number density profile of satellite galaxies to be a projected power law such that $P(R)\\propto R^{\\rpower}$, we find $\\rpower=-1.1\\pm 0.3$. We find no dependency of $\\rpower$ on host stellar mass, redshift, morphology or satellite luminosity. Satellites of early-type hosts have angular distributions that are more flattened than the host light profile and are aligned with its major axis. No significant average alignment is detected for satellites of late-type hosts. The number of satellites within a fixed magnitude contrast from a host galaxy is depe...

Nierenberg, A M; Treu, T; Marshall, P J; Fassnacht, C D; Busha, Michael T

2012-01-01

362

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

CERN Document Server

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.

Zaninetti, L

2014-01-01

363

The Luminosity Function of Galaxies as Modeled by a Left Truncated Beta Distribution  

Directory of Open Access Journals (Sweden)

Full Text Available A first new luminosity function 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.

L. Zaninetti

2014-03-01

364

Preliminary study of a high luminosity e+ e- storage ring at a C.M. energy of 5 GeV  

International Nuclear Information System (INIS)

The design of a facility for the study of tau-charm interactions, with 5 GeV C.M. energy and a luminosity of 1033/sqcm.s is investigated. The performances of some known storage rings are underlined. The influence of the emittances, space charge and collision rate limit, and the design constraints of the micro beta quadrupoles are discussed. Design examples and considerations of the sloping parts are included. The analysis shows that the round beam scheme saves a factor 2 on the stored current for a given luminosity, is very demanding in terms of tolerances for superconducting quadrupoles and requires one crossing point

365

A Systematic Search for Molecular Outflows Toward Candidate Low-Luminosity Protostars and Very Low Luminosity Objects  

CERN Document Server

We present a systematic single-dish search for molecular outflows toward a sample of 9 candidate low-luminosity protostars and 30 candidate Very Low Luminosity Objects (VeLLOs; L_int < 0.1 L_sun). The sources are identified using data from the Spitzer Space Telescope catalogued by Dunham et al. toward nearby (D < 400 pc) star forming regions. Each object was observed in 12CO and 13CO J = 2-1 simultaneously using the sideband separating ALMA Band-6 prototype receiver on the Heinrich Hertz Telescope at 30 arcsecond resolution. Using 5-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 fro...

Schwarz, Kamber R; Dunham, Michael M

2012-01-01

366

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

CERN Document Server

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.

Ellis, S C

2002-01-01

367

GALAXY CLUSTERING AND PROJECTED DENSITY PROFILES AS TRACED BY SATELLITES IN PHOTOMETRIC SURVEYS: METHODOLOGY AND LUMINOSITY DEPENDENCE  

International Nuclear Information System (INIS)

We develop a new method which measures the projected density distribution wp (rp )n of photometric galaxies surrounding a set of spectroscopically identified galaxies and simultaneously the projected cross-correlation function wp (rp ) between the two populations. In this method, we are able to divide the photometric galaxies into subsamples in luminosity intervals even when redshift information is unavailable, enabling us to measure wp (rp )n and wp (rp ) as a function of not only the luminosity of the spectroscopic galaxy, but also that of the photometric galaxy. Extensive tests show that our method can measure wp (rp ) in a statistically unbiased way. The accuracy of the measurement depends on the validity of the assumption inherent to the method that the foreground/background galaxies are randomly distributed and are thus uncorrelated with those galaxies of interest. Therefore, our method can be applied to the cases where foreground/background galaxies are distributed in large volumes, which is usually valid in real observations. We have applied our method to data from the Sloan Digital Sky Survey (SDSS) including a sample of 105 luminous red galaxies at z ? 0.4 and a sample of about half a million galaxies at z ? 0.1, both of which are cross-correlated with a deep photometric sample drawn from the SDSS. On large scales, the relative bias factor of galaxies measured from wp (rp ) at z ? 0.4 depends on luminosity in a manner similar to what is found for those at z ? 0.1, which are usually probed by autocorrelations of spectroscopic samples in previous studies. On scales smaller than a few Mpc and at both z ? 0.4 and z ? 0.1, the photometric galaxies of different luminosities exhibit similar density profiles around spectroscopic galaxies at fixed luminosity and redshift. This provides clear observational support for the assumption commonly adopted in halo occupation distribution models that satellite galaxies of different luminosities are distributed in a similar way, following the dark matter distribution within their host halos.

368

Luminosity distance and redshift in the Szekeres inhomogeneous cosmological models  

International Nuclear Information System (INIS)

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

369

Globular Clusters and the Mira Period-Luminosity Relation  

CERN Document Server

A globular cluster distance scale based on Hipparcos parallaxes of subdwarfs has been used to derive estimates of M_K for cluster Miras, including one in the SMC globular cluster NGC121. These lead to a zero-point of the Mira infrared period-luminosity relation, PL(K), in good agreement with that derived from Hipparcos parallaxes of nearby field Miras. The mean of these two estimates together with data on LMC Miras yields an LMC distance modulus of 18.60 +/- 0.10 in evident agreement with a metallicity corrected Cepheid modulus (18.59 +/- 0.10). The use of luminous AGB stars as extragalactic population indicators is also discussed.

Feast, M W; Menzies, J; Feast, Michael; Whitelock, Patricia; Menzies, John

2002-01-01

370

Kinematic corrections to the averaged luminosity distance in inhomogeneous universes  

CERN Document Server

The redshift surfaces within inhomogeneous universes are shifted by the matter peculiar velocities. The arising average corrections to the luminosity distance are calculated relativistically in several Swiss-cheese models with mass compensated Lemaitre-Tolman-Bondi voids. These kinematic corrections are different from weak lensing effects and can be much bigger close to the observer. The statistical averaging over all directions is performed by tracing numerically light rays propagating through a random void lattice. The probability of a supernova emision from a comoving volume is assumed proportional to the rest mass in it. The average corrections to the distance modulus can be significant for redshifts smaller than 0.02 for small voids (radius 30 Mpc) and redshifts smaller than 0.1 for big voids (radius 300 Mpc), yet not large enough to substitute for dark energy. The corrections decay inversely proportional to the distance from the observer. In addition, there is a random cancelation of corrections between...

Kostov, Valentin

2010-01-01

371

The Herschel Virgo Cluster Survey: I. Luminosity functions  

CERN Document Server

We describe the Herschel Virgo Cluster Survey (HeViCS) and the first data obtained as part of the Science Demonstration Phase (SDP). The data cover a central 4x4 sq deg region of the cluster. We use SPIRE and PACS photometry data to produce 100, 160, 250, 350 and 500 micron luminosity functions (LFs) for optically bright galaxies that are selected at 500 micron and detected in all bands. We compare these LFs with those previously derived using IRAS, BLAST and Herschel-ATLAS data. The Virgo Cluster LFs do not have the large numbers of faint galaxies or examples of very luminous galaxies seen previously in surveys covering less dense environments.

Davies, J I; Bendo, G J; Bianchi, S; Bomans, D J; Boselli, A; Clemens, M; Corbelli, E; Cortese, L; Dariush, A; De Looze, I; Alighieri, S di Serego; Fadda, D; Fritz, J; Garcia-Appadoo, D A; Gavazzi, G; Giovanardi, C; Grossi, M; Hughes, T M; Hunt, L K; Jones, A P; Madden, S; Pierini, D; Pohlen, M; Sabatini, S; Smith, M W L; Verstappen, J; Vlahakis, C; Xilouris, E M; Zibetti, S

2010-01-01

372

CMS in the high luminosity era of the LHC  

CERN Document Server

In this presentation, the presentations and discussions of the workshop are summarized. LHC and CMS progress in physics thus far are covered along with the status of the Higgs and related new physics searches. The absence of new physics in any searches has created some stir in the theoretical community, emphasizing the need for greater input from the experimental side. Lessons for the near term are considered, followed by a look forward to potential future High Luminosity and High Energy eras of operation for the LHC. The potential new physics landscape to be explored remains fairly broad as presented in many talks at the workshop. Properties of a Higgs at 125–126 GeV could be studied in these future periods. In the Higgs sector the key items to be measured are delineated and related back to the needs of CMS upgrades. The opportunities and challenges are both very great.

Incandela, J

2013-01-01

373

CdTe Photoconductors for LHC Luminosity Monitoring  

CERN Document Server

Detectors using CdTe photoconductors are being used with great success in LEP to monitor the vertical beam emittance. They can withstand tremendous irradiation, of up to 10^13 Gy, from hard X-rays. For the LHC, monitors measuring the relative luminosity will be placed inside absorbers located 142 m from the interaction points, where they will receive about 10^8 Gy per year due to gamma radiation and neutrons. Thick-polycristalline-CdTe detectors were recently tested for speed, sensitivity and radiation resistance before and after receiving up to 10^15 neutrons per cm^2. The test results are presented here, along with a comparison of the calculated charge deposition in Silicon, Diamond and GaAs detectors.

Rossa, E; Meier, D; Schmickler, Hermann; Verger, L; Mongellaz, F; Rumen, G

2002-01-01

374

Redshift drift and luminosity distance in VSL cosmology  

CERN Document Server

We derive a redshift drift formula within the framework of varying speed of light (VSL) theory using the specific ansatz for the variability of $c(t) = c_0 a^n(t)$. We show that negative values of the parameter $n$, which corresponds to diminishing value of the speed of light during the evolution of the universe, effectively rescales dust matter to become little negative pressure matter and the cosmological constant to became phantom. Positive values of $n$ (growing $c(t)$) make VSL model to become more like Cold Dark Matter (CDM) model. We also present the luminosity distance formula for the VSL theory which involves higher order characteristics of expansion such as jerk and snap which can test the impact of varying speed of light $c$ onto the kinematics of the universe.

Balcerzak, Adam

2013-01-01

375

Present and past neutrino luminosity of the sun  

International Nuclear Information System (INIS)

The neutrino radiation from the sun can give direct information on the basic nuclear fusion processes that provide the solar energy. Results are reported which have been obtained over the last seven years with the Brookhaven solar neutrino detector that depends upon the neutrino capture reaction, 37Cl(?,e-)37 Ar. These results do not agree with the predictions of the standard solar model. It is of great interest to know whether the lack of agreement between the measurements and theoretical expectation could possibly be explained by a secular variation in the rate of the fusion process. Two radiochemical neutrino detection techniques have been proposed previously that could in principle record the neutrino flux of the past. An analysis of the expected background processes for these experiments is given. These and other possible methods of recording the past solar neutrino luminosity are discussed in relation to variations expected from theoretical solar models. 2 figures, 6 tables, 36 references

376

Models of hydrostatic magnetar atmospheres at high luminosities  

CERN Document Server

We investigate the possibility of Photospheric Radius Expansion (PRE) during magnetar bursts. Identification of PRE would enable a determination of the magnetic Eddington limit (which depends on field strength and neutron star mass and radius), and shed light on the burst mechanism. To do this we model hydrostatic atmospheres in a strong radial magnetic field, determining both their maximum extent and photospheric temperatures. We find that spatially-extended atmospheres cannot exist in such a field configuration: typical maximum extent for magnetar-strength fields is ~ 10m (as compared to 200 km in the non-magnetic case). Achieving balance of gravitational and radiative forces over a large range of radii, which is critical to the existence of extended atmospheres, is rendered impossible in strong fields due to the dependence of opacities on temperature and field strength. We conclude that high luminosity bursts in magnetars do not lead to expansion and cooling of the photosphere, as in the non-magnetic case....

van Putten, T; D'Angelo, C R; Baring, M G; Kouveliotou, C

2012-01-01

377

Operating microscope in Endodontics: visual magnification and luminosity  

Directory of Open Access Journals (Sweden)

Full Text Available Introduction: The surgical microscope has been used in Endodontics in order to minimize the obscurity of the surgical field, because it provides a high magnification and luminosity, thereby enhancing the procedures performed and providing a final result of higher quality. Objective and literature review: The objective of this study was to review the literature by addressing the current situation of the operating microscope in Endodontics, emphasizing its advantages and limitations. Despite being a technological tool that is relatively costly and that requires a period of learning and adaptation, the use of this apparatus has been spreading gradually. Conclusion: The importance of magnification is scientifically based in Dentistry,in such a way that its use has provided significant improvement to Endodontics with regards to vision and lighting of the operative field, by offering better quality of work with proportional success rates in treatments, besides improving communication between professionals and patients and assisting in the documentation for legal purposes.

Letícia Moreira Feix

2010-07-01

378

Masses, radii, temperatures, luminosities and surface compositions of white dwarfs  

Science.gov (United States)

The masses, radii, temperature, luminosities and compositions of white dwarf stars are discussed, with particular emphasis on those areas in which considerable work remains to be done. It is pointed out that radii for stars of known parallax are available, together with masses and their variance. Consideration is then given to the difficulties involved in the determination of the temperatures of the hottest stars and helium stars by means of Stromgren or multichannel photometry, and it is noted that the frequency of binaries among the hottest degenerates seems too high to be due to chance. Results of IUE observations of the UV spectra of three DA and one DO star are discussed, with attention given to the similarities between UV-derived and ground-based determinations of temperatures and surface gravities. The metal abundances of hydrogen and helium degenerate stars are finally considered, and spectral classes and abundances of the helium atmosphere degenerates are tabulated.

Greenstein, J. L.

1979-01-01

379

The Origin of Intermediate-Luminosity Red Transients  

Science.gov (United States)

Intermediate-luminosity red transients (ILRTs) are a new class of optical transients. They have maximum luminosities between novae and SNe, and outbursts lasting several months, becoming cool, dusty, and extremely red as the eruptions proceed. A prototype is V838 Mon, which illuminated a spectacular light echo. Their outbursts may be due to catastrophic stellar collisions and mergers. This is demonstrably true for V1309 Sco, which was a contact binary before its eruption and is now a single star. However, it is not yet clear whether all ILRTs are due to mergers.I propose WFC3 imaging of 3 ILRTs: (1) V4332 Sgr, which erupted in the Galactic bulge in 1994, is now a 19th-mag, very red remnant. Based on a high degree of linear polarization in ground-based measurements, it has been proposed that it is surrounded and obscured by a dusty, edge-on envelope, ejected during a stellar merger. If so, V4332 Sgr ought to display a dark lane at HST imaging resolution. (2) M31 RV is an ILRT that occurred in the bulge of M31 in 1988. HST images of the site taken between 1999 and 2010 failed to reveal a credible remnant of this event. However, models of expanding dusty envelopes predict that eventually, as the optical depth diminishes, the remnant should brighten. The passage of 5 years since the last HST observation of the field justifies another attempt to identify the putative merged binary. (3) CK Vul, the bright "nova" of 1670, is a candidate ILRT because of its red color and an outburst light curve resembling that of V838 Mon. A faint bipolar nebula lies at the site of CK Vul, but no credible remnant star has been found in ground-based images. HST resolution may reveal it.

Bond, Howard

2014-10-01

380

The B-band luminosities of quasar host galaxies  

Science.gov (United States)

We report on the analysis of B-band imaging data of 57 low-redshift quasi-stellar objects (quasars/QSOs) and Seyfert 1 galaxies selected from the Hamburg/ESO Survey, for which host-galaxy-dependent selection biases are greatly reduced compared with other optical surveys. Only one object in the sample is known to be radio-loud. We adopted a procedure to remove the active galactic nuclei (AGN) contribution by subtracting a scaled point spread function from each QSO image. To reclaim the integrated host galaxy flux we correct for oversubtraction based on simulations. This method is quite insensitive to the host galaxy morphological type, which we can unambiguously establish for 15 of the 57 objects. The quasar host galaxies are detected in all cases. The hosts are very luminous, ranging in absolute magnitude MB from -19.0 to -23.8, with an average of MB,gal=-21.5, considerably above L* for field galaxies. For the luminous QSO subsample with MB < -23 the average host absolute magnitude is MB,gal=-23.0, while for the complementary low-luminosity AGN we obtain MB,gal=-21.2, roughly equal to L*. The luminous host galaxies in the sample are typically ~1 mag brighter than expected when inferring B-band luminosities from studies of similar objects at longer wavebands. We argue that this mismatch is not likely to be explained by selection effects, but favours host galaxy colours significantly bluer than those of inactive galaxies. Although published B-band data are scant, this result and the findings of other authors are in good agreement.

Jahnke, Knud; Wisotzki, Lutz

2003-11-01

 
 
 
 
381

The SCUBA Local Universe Galaxy Survey - I. First measurements of the submillimetre luminosity and dust mass functions  

Science.gov (United States)

This is the first of a series of papers presenting results from the SCUBA Local Universe Galaxy Survey (SLUGS), the first statistical survey of the submillimetre properties of the local Universe. As the initial part of this survey, we have used the SCUBA camera on the James Clerk Maxwell Telescope to observe 104 galaxies from the IRAS Bright Galaxy Sample. We present here the 850-?m flux measurements. The 60-, 100-, and 850-?m flux densities are well fitted by single-temperature dust spectral energy distributions, with the sample mean and standard deviation for the best-fitting temperature being Td=35.6+/-4.9K and for the dust emissivity index ?=1.3+/-0.2. The dust temperature was found to correlate with 60-?m luminosity. The low value of ? may simply mean that these galaxies contain a significant amount of dust that is colder than these temperatures. We have estimated dust masses from the 850-?m fluxes and from the fitted temperature, although if a colder component at around 20K is present (assuming a ? of 2), then the estimated dust masses are a factor of 1.5-3 too low. We have made the first direct measurements of the submillimetre luminosity function (LF) and of the dust mass function. Unlike the IRAS 60-?m LF, these are well fitted by Schechter functions. The slope of the 850-?m LF at low luminosities is steeper than -2, implying that the LF must flatten at luminosities lower than we probe here. We show that extrapolating the 60-?m LF to 850?m using a single temperature and ? does not reproduce the measured submillimetre LF. A population of `cold' galaxies (Tdcold dust' component at Td<=20K in our galaxies. There is a surprisingly tight correlation between dust mass and the mass of molecular hydrogen, estimated from CO measurements, with an intrinsic scatter of ~=50per cent.

Dunne, Loretta; Eales, Stephen; Edmunds, Michael; Ivison, Rob; Alexander, Paul; Clements, David L.

2000-06-01

382

Measurement of the luminosity in the ZEUS experiment at HERA II  

Science.gov (United States)

The luminosity in the ZEUS detector was measured using photons from electron bremsstrahlung off protons. 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.

Adamczyk, L.; Andruszkow, J.; Bold, T.; Borzemski, P.; Buettner, C.; Caldwell, A.; Chwastowski, J.; Daniluk, W.; Drugakov, V.; Eskreys, A.; Figiel, J.; Galas, A.; Gil, M.; Helbich, M.; Januschek, F.; Jurkiewicz, P.; Kisielewska, D.; Klein, U.; Kotarba, A.; Lohmann, W.; Ning, Y.; Oliwa, K.; Olkiewicz, K.; Paganis, S.; Pieron, J.; Przybycien, M.; Ren, Z.; Ruchlewicz, W.; Schmidke, W.; Schneekloth, U.; Sciulli, F.; Stopa, P.; Sztuk-Dambietz, J.; Suszycki, L.; Sutiak, J.; Wierba, W.; Zawiejski, L.

2014-04-01

383

Measurement of the Luminosity in the ZEUS Experiment at HERA II  

CERN Document Server

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.

Adamczyk, L; Bold, T; Borzemski, P; Buettner, C; Caldwell, A; Chwastowski, J; Daniluk, W; Drugakov, V; Eskreys, A; Figiel, J; Galas, A; Gil, M; Helbich, M; Januscheck, F; Jurkiewicz, P; Kisielewska, D; Klein, U; Kotarba, A; Lohmann, W; Ning, Y; Oliwa, K; Olkiewicz, K; Paganis, S; Pieron, J; Przybycien, M; Ren, Z; Ruchlewicz, W; Schmidke, W; Schneekloth, U; Sciulli, F; Stopa, P; Sztuk-Dambietz, J; Suszycki, L; Sutiak, J; Wierba, W; Zawiejski, L

2013-01-01

384

Measurement of the luminosity in the ZEUS experiment at HERA II  

Energy Technology Data Exchange (ETDEWEB)

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.

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

385

Field Tolerances for the Triplet Quadrupoles of the LHC High Luminosity Lattice  

CERN Document Server

It has been proposed to implement the so-called Achromatic Telescopic Squeezing (ATS) scheme [1] in the LHC high luminosity (HL) lattice to reduce beta functions at the Interaction Points (IP) up to a factor of 8. As a result, the nominal 4.5 km peak beta functions reached in the Inner Triplets (IT) at collision will be increased by the same factor. This, therefore, justi?es the installation of new, larger aperture, superconducting IT quadrupoles. The higher beta functions will enhance the effects of the triplet quadrupole ?eld errors leading to smaller beam dynamic aperture (DA). To maintain the acceptable DA, the effects of the triplet ?eld errors must be re-evaluated, thus specifying new tolerances. Such a study has been performed for the so-called “4444” collision option of the HL-LHC layout version SLHCV3.01, where the IP beta functions are reduced by a factor of 4 in both planes with respect to a pre-squeezed value of 60 cm at two collision points. The dynamic aperture calculations were perfor...

Nosochkov, Y; Jiao, Y; Wang, M-H; Fartoukh, S; Giovannozzi, M; de Maria, R; McIntosh, E

2012-01-01

386

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Hayward, Christopher C.; Lanz, Lauranne; Ashby, Matthew L. N.; Fazio, Giovanni; Hernquist, Lars; Marti?nez-galarza, Juan Rafael; Noeske, Kai; Smith, Howard A.; Wuyts, Stijn; Zezas, Andreas

2014-01-01

387

AKARI IRC 2.5-5 ?m Spectroscopy of Infrared Galaxies over a Wide Luminosity Range  

Science.gov (United States)

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 ? 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.

Ichikawa, Kohei; Imanishi, Masatoshi; Ueda, Yoshihiro; Nakagawa, Takao; Shirahata, Mai; Kaneda, Hidehiro; Oyabu, Shinki

2014-10-01

388

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

Science.gov (United States)

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.

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

389

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

CERN Document Server

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.

Esberg, Jakob; Uggerhoj, Ulrik; Dalena, Barbara

2011-01-01

390

PHOTOMETRIC PROPERTIES AND LUMINOSITY FUNCTION OF NEARBY MASSIVE EARLY-TYPE GALAXIES  

Energy Technology Data Exchange (ETDEWEB)

We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (M{sub r} < -22.5 mag) in the redshift range of 0.05-0.15, drawn from the Sloan Digital Sky Survey (SDSS) DR7 with morphological classification from Galaxy Zoo 1. We measure the Petrosian and isophotal magnitudes, as well as the corresponding half-light radius for each galaxy. We find that for the brightest galaxies (M{sub r} < -23 mag), our Petrosian magnitudes and isophotal magnitudes to 25 mag arcsec{sup -2} and 1% of the sky brightness are on average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian values, respectively. In the first case, the underestimations are caused by overestimations in the sky background by the SDSS PHOTO algorithm, while the latter two are also due to deeper photometry. Similarly, the typical half-light radii (r{sub 50}) measured by the SDSS algorithm are smaller than our measurements. As a result, the bright end of the r-band luminosity function is found to decline more slowly than previous works. Our measured luminosity densities at the bright end are more than one order of magnitude higher than those of Blanton et al., and the stellar mass densities at M{sub *} {approx} 5 Multiplication-Sign 10{sup 11} M{sub Sun} and M{sub *} {approx} 10{sup 12} M{sub Sun} are a few tenths and a factor of a few higher than those of Bernardi et al. These results may significantly alleviate the tension in the assembly of massive galaxies between observations and predictions of the hierarchical structure formation model.

He, Y. Q. [University of Chinese Academy of Sciences, Beijing 100049 (China); Xia, X. Y.; Hao, C. N. [Tianjin Astrophysics Center, Tianjin Normal University, Tianjin 300387 (China); Jing, Y. P. [Center for Astronomy and Astrophysics, Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Mao, S. [National Astronomical Observatories, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing 100012 (China); Li, Cheng, E-mail: xyxia@bao.ac.cn [Partner Group of the Max Planck Institute for Astrophysics at the Shanghai Astronomical Observatory and Key Laboratory for Research in Galaxies and Cosmology of Chinese Academy of Sciences, Nandan Road 80, Shanghai 200030 (China)

2013-08-10

391

Constraining the minimum luminosity of high redshift galaxies through gravitational lensing  

Science.gov (United States)

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 zgtrsim 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 zgtrsim 6 and zgtrsim 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.

Mashian, Natalie; Loeb, Abraham

2013-12-01

392

Variability Selected Low-Luminosity Active Galactic Nuclei in the 4 Ms Chandra Deep Field-South  

Science.gov (United States)

The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGN). However, cosmologically distant low-luminosity AGN (LLAGN) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X ray variability (approx. month years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts approx equals 00.8 - 1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole. The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of Gamma(sub Stack) approx equals 1.93 +/- 0.13, and arc therefore likely LLAGN. The LLAGN tend to lie it factor of approx equal 6-89 below the extrapolated linear variability-luminosity relation measured for luminous AGN. This may he explained by their lower accretion rates. Variability-independent black-hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

Young, M.; Brandt, W. N.; Xue, Y. Q.; Paolillo, D. M.; Alexander, F. E.; Bauer, F. E.; Lehmer, B. D.; Luo, B.; Shemmer, O.; Schneider, D. P.; Vignail, C.

2012-01-01

393

VARIABILITY-SELECTED LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN THE 4 Ms CHANDRA DEEP FIELD-SOUTH  

International Nuclear Information System (INIS)

The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGNs). However, cosmologically distant low-luminosity AGNs (LLAGNs) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (?month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z ? 0.08-1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole (SMBH). The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of ?stack ? 1.93 ± 0.13, and are therefore likely LLAGNs. The LLAGNs tend to lie a factor of ?6-80 below the extrapolated linear variability-luminosity relation measured for luminous AGNs. This may be explained by their lower accretion rates. Variability-independent black hole mass and accretion-rate estimates for variable galaxies show that they sample a significantly different black hole mass-accretion-rate space, with masses a factor of 2.4 lower and accretion rates a factor of 22.5 lower than variable luminous AGNs at the same redshift. We find that an empirical model based on a universal broken power-law power spectral density function, where the break frequency depends on SMBH mass and accretion rate, roughly reproduces the shape, but not the normalization, of the variability-luminosity trends measured for variable galaxies and more luminous AGNs.

394

The Luminosity Profile and Structural Parameters of the Andromeda Galaxy  

Science.gov (United States)

We have constructed an extended composite luminosity profile for the Andromeda galaxy, M31, and have decomposed it into three basic luminous structural components: a bulge, a disk, and a halo. The dust-free Spitzer/Infrared Array Camera (IRAC) imaging and extended spatial coverage of ground-based optical imaging and deep star counts allow us to map M31's structure from its center to 22 kpc along the major axis. We apply, and address the limitations of, different decomposition methods for the one-dimensional luminosity profiles and two-dimensional images. These methods include nonlinear least-squares and Bayesian Monte Carlo Markov chain analyses. The basic photometric model for M31 has a Sérsic bulge with shape index n ~= 2.2 ± .3 and effective radius Re = 1.0 ± 0.2 kpc, and a dust-free exponential disk of scale length Rd = 5.3 ± .5 kpc the parameter errors reflect the range between different decomposition methods. Despite model covariances, the convergence of solutions based on different methods and current data suggests a stable set of structural parameters. The ellipticities (epsilon = 1 - b/a) of the bulge and the disk from the IRAC image are 0.37 ± 0.03 and 0.73 ± 0.03, respectively. The bulge parameter n is rather insensitive to bandpass effects and its value (2.2) suggests a first rapid formation via mergers followed by secular growth from the disk. The M31 halo has a two-dimensional power-law index ~= - 2.5 ± 0.2 (or -3.5 in three-dimensional), comparable to that of the Milky Way. We find that the M31 bulge light is mostly dominant over the range R min ~ 9 kpc. The stellar nucleus, bulge, disk, and halo components each contribute roughly 0.05%, 23%, 73%, and 4% of the total light of M31 out to 200 kpc along the minor axis. Nominal errors for the structural parameters of the M31 bulge, disk, and halo amount to 20%. If M31 and the Milky Way are at all typical, faint stellar halos should be routinely detected in galaxy surveys reaching below ? i ~= 27 mag arcsec-2. We stress that our results rely on this photometric analysis alone. Structural parameters may change when other fundamental constraints, such as those provided by abundance gradients and stellar kinematics, are considered simultaneously.

Courteau, Stéphane; Widrow, Lawrence M.; McDonald, Michael; Guhathakurta, Puragra; Gilbert, Karoline M.; Zhu, Yucong; Beaton, Rachael Lynn; Majewski, Steven R.

2011-09-01

395

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 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.

396

The HELLAS2XMM Survey. VII. The Hard X-Ray Luminosity Function of AGNs up to z = 4: More Absorbed AGNs at Low Luminosities and High Redshifts  

Science.gov (United States)

We have determined the cosmological evolution of the density of active galactic nuclei (AGNs) and of their NH distribution as a function of the unabsorbed 2-10 keV luminosity up to redshift 4. We used the HELLAS2XMM sample combined with other published catalogs, yielding a total of 508 AGNs. Our best fit is obtained with a luminosity-dependent density evolution (LDDE) model where low-luminosity (LX~1043 ergs s-1) AGNs peak at z~0.7, while high-luminosity AGNs (LX>1045 ergs s-1) peak at z~2.0. A pure luminosity evolution model (PLE) can instead be rejected. There is evidence that the fraction of absorbed (NH>1022 cm-2) AGNs decreases with the intrinsic X-ray luminosity and increases with the redshift. Our best-fit solution provides a good fit to the observed counts, the cosmic X-ray background, and to the observed fraction of absorbed AGNs as a function of the flux in the 10-15 ergs cm-2 s-11044 ergs s-1) AGNs have a density of 267 deg-2 at fluxes S2-10>10-15 ergs cm-2 s-1. Using these results, we estimate a density of supermassive black holes in the local universe of ?BH=3.2 h270×105 Msolar Mpc-3, which is consistent with the recent measurements of the black hole mass function in the local galaxies.

La Franca, F.; Fiore, F.; Comastri, A.; Perola, G. C.; Sacchi, N.; Brusa, M.; Cocchia, F.; Feruglio, C.; Matt, G.; Vignali, C.; Carangelo, N.; Ciliegi, P.; Lamastra, A.; Maiolino, R.; Mignoli, M.; Molendi, S.; Puccetti, S.

2005-12-01

397

The HELLAS2XMM survey. VII. The hard X-ray luminosity function of AGN up to z=4: more absorbed AGN at low luminosities and high redshifts  

CERN Document Server

We have determined the cosmological evolution of the density of AGN and of their Nh distribution as a function of the un-absorbed 2-10 keV luminosity up to redshift 4. We used the HELLAS2XMM sample combined with other published catalogs, yielding a total of 508 AGN. Our best fit is obtained with a luminosity-dependent density evolution (LDDE) model where low luminosity (Lx~10^43 erg s^-1) AGN peak at z~0.7, while high luminosity AGN (Lx>10^45 erg s^-1) peak at z~2.0. A pure luminosity evolution model (PLE) can instead be rejected. There is evidence that the fraction of absorbed (Nh>10^22 cm^-2) AGN decreases with the intrinsic X-ray luminosity, and increases with the redshift. Our best fit solution provides a good fit to the observed counts, the cosmic X-ray background, and to the observed fraction of absorbed AGN as a function of the flux in the 10^-1510^44 erg s^-1) AGN have a density of 267 deg^-2 at fluxes S(2-10)>10^-15 erg s^-1 cm^-2. Using these results, we estimate a density of supermassive black hole...

La Franca, F; Comastri, A; Perola, G C; Sacchi, N; Brusa, M; Cocchia, F; Feruglio, C; Matt, G; Vignali, C; Carangelo, N; Ciliegi, P; Lamastra, A; Maiolino, R; Mignoli, M; Molendi, S; Puccetti, S

2005-01-01

398

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

399

Tevatron energy and luminosity upgrades beyond the main injector  

CERN Document Server

The Fermilab Tevatron will be the world's highest energy hadron collider until the LHC is commissioned, it has the world's highest energy fixed target beams, and Fermilab will be the leading high energy physics laboratory in the US for the foreseeable future. Following the demise of the SSC, a number of possible upgrades to the Tevatron complex, beyond construction of the Main Injector, are being discussed. Using existing technology, it appears possible to increase the luminosity of the \\bar{p}p Collider to at least 10^{33}cm^{-2}sec^{-1} (Tevatron-Star) and to increase the beam energy to 2 TeV (DiTevatron). Fixed target beam of energy about 1.5 TeV could also be delivered. Leaving the existing Tevatron in the tunnel and constructing bypasses around the collider halls would allow simultaneous 800 GeV fixed target and \\sqrt{s} = 4 TeV collider operation. These upgrades would give Fermilab an exciting physics program which would be complementary to the LHC, and they would lay the groundwork for the construction...

Amidei, D; Foster, G W; Jackson, G P; Kamon, T; López, J L; McIntyre, P; Strait, J B; White, J

1996-01-01

400

Isochrones and Luminosity Functions for Old White Dwarfs  

CERN Document Server

Using a new grid of models of cooling white dwarfs, we calculate isochrones and luminosity functions in the Johnson-Kron/Cousins and HST filter sets for systems containing old white dwarfs. These new models incorporate a non-grey atmosphere which is necessary to properly describe the effects of molecular opacity at the cool temperatures of old white dwarfs. The various functions calculated and extensively tabulated and plotted are meant to be as utilitarian as possible for observers so all results are listed in quantities that observers will obtain. The tables and plots developed should eventually prove critical in interpreting the results of HST's Advanced Camera observations of the oldest white dwarfs in nearby globular clusters, in understanding the results of searches for old white dwarfs in the Galactic halo, and in determining ages for star clusters of all ages using white dwarfs. As a practical application we demonstrate the use of these results by deriving the white dwarf cooling age of the old Galact...

Richer, H B; Limongi, M; Chieffi, A; Straniero, O; Fahlman, G G; Richer, Harvey B.; Hansen, Brad; Limongi, Marco; Chieffi, Alessandro; Straniero, Oscar; Fahlman, Gregory G.

1999-01-01

 
 
 
 
401

The Evolving Faint End of the Luminosity Function  

CERN Document Server

We investigate the evolution of the faint-end slope of the luminosity function, $\\alpha$, using semi-analytical modeling of galaxy formation. In agreement with observations, we find that the slope can be fitted well by $\\alpha (z) =a+b z$, with a=-1.13 and b=-0.1. The main driver for the evolution in $\\alpha$ is the evolution in the underlying dark matter mass function. Sub-L_* galaxies reside in dark matter halos that occupy a different part of the mass function. At high redshifts, this part of the mass function is steeper than at low redshifts and hence $\\alpha$ is steeper. Supernova feedback in general causes the same relative flattening with respect to the dark matter mass function. The faint-end slope at low redshifts is dominated by field galaxies and at high redshifts by cluster galaxies. The evolution of $\\alpha(z)$ in each of these environments is different, with field galaxies having a slope b=-0.14 and cluster galaxies b=-0.05. The transition from cluster-dominated to field-dominated faint-end slop...

Khochfar, S; Windhorst, R A; Ryan, R E

2007-01-01

402

Large-Angle Bhabha Scattering and Luminosity at Flavour Factories  

CERN Document Server

The luminosity determination of electron-positron colliders operating in the region of low-lying hadronic resonances (E_cm ~ 1-10 GeV), such as BEPC/BES, DAPHNE, 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(alpha) corrections and higher-order leading logarithmic contributions, is developed as well and compared in detail with the PS predictions. The effect of O(alpha) 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 gen...

Calame, Carlo M Carloni; Montagna, G; Nicrosini, O; Piccinini, Fulvio

2000-01-01

403

On the perturbation of the luminosity distance by peculiar motions  

CERN Document Server

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...

Kaiser, Nick

2014-01-01

404

An Anthropology of Luminosity : the Agency of Light  

DEFF Research Database (Denmark)

This article addresses the relationship between light, material culture and social experiences. It argues that understanding light as a powerful social agent, in its relationship with people, things, colours, shininess and places, may facilitate an appreciation of the active social role of luminosity in the practice of day-to-day activities. The article surveys an array of past conceptions of light within philosophy, natural science and more recent approaches to light in the fields of anthropology and material culture studies. A number of implications are discussed, and by way of three case studies it is argued that light may be used as a tool for exercising social intimacy and inclusion, of shaping moral spaces and hospitality, and orchestrating movement, while working as a metaphor as well as a material agent in these social negotiations. The social comprehension of light is a means of understanding social positions in ways that may be real or imagined, but are bound up on the social and cultural associations of certain lightscapes

Bille, Mikkel; SØrensen, Tim Flohr

2007-01-01

405

MULTI-WAVELENGTH CHARACTERISTICS OF PERIOD-LUMINOSITY RELATIONS  

Energy Technology Data Exchange (ETDEWEB)

We present a physically motivated explanation for the observed, monotonic increase in slope, and the simultaneous (and also monotonic) decrease in the width/scatter of the Leavitt law (the Cepheid period-luminosity (PL) relation) as one systematically moves from the blue and visual into the near- and mid-infrared. We calibrate the wavelength-dependent, surface-brightness sensitivities to temperature using the observed slopes of PL relations from the optical through the mid-infrared and test the calibration by comparing the theoretical predictions with direct observations of the wavelength dependence of the scatter in the Large Magellanic Cloud Cepheid PL relation. In doing so we find the slope of the period-radius (PR) relation is c = 0.724 {+-} 0.006. Investigating the effect of differential reddening suggests that this value may be overestimated by as much as 10%; however, the same slope of the PR relation fits the (very much unreddened) Cepheids in IC 1613, albeit with lower precision. The discussion given is general and also applies to RR Lyrae stars, which also show similarly increasing PL slopes and decreasing scatter with increasing wavelength.

Madore, Barry F.; Freedman, Wendy L., E-mail: barry@obs.carnegiescience.edu, E-mail: wendy@obs.carnegiescience.edu [Observatories of the Carnegie Institution of Washington 813 Santa Barbara St., Pasadena, CA 91101 (United States)

2012-01-10

406

MULTI-WAVELENGTH CHARACTERISTICS OF PERIOD-LUMINOSITY RELATIONS  

International Nuclear Information System (INIS)

We present a physically motivated explanation for the observed, monotonic increase in slope, and the simultaneous (and also monotonic) decrease in the width/scatter of the Leavitt law (the Cepheid period-luminosity (PL) relation) as one systematically moves from the blue and visual into the near- and mid-infrared. We calibrate the wavelength-dependent, surface-brightness sensitivities to temperature using the observed slopes of PL relations from the optical through the mid-infrared and test the calibration by comparing the theoretical predictions with direct observations of the wavelength dependence of the scatter in the Large Magellanic Cloud Cepheid PL relation. In doing so we find the slope of the period-radius (PR) relation is c = 0.724 ± 0.006. Investigating the effect of differential reddening suggests that this value may be overestimated by as much as 10%; however, the same slope of the PR relation fits the (very much unreddened) Cepheids in IC 1613, albeit with lower precision. The discussion given is general and also applies to RR Lyrae stars, which also show similarly increasing PL slopes and decreasing scatter with increasing wavelength.

407

The LMC stellar complexes in luminosity slices. Star formation indicators  

Science.gov (United States)

An approach towards the investigation of the star formation mechanisms in galaxies can be achieved through the search of stellar complexes and the determination of their properties. A method has been developed for the detection of stellar complexes and the derivation of their fundamental properties in the LMC. Photographic plates taken with the 1.2m U.K. Schmidt Telescope have been digitized by the APM and SuperCosmos machines to produce homogeneous data for extended regions. Star counts have been performed for extended areas in selected luminosity slices and colours (U, HeII, R filters). Isodensity contours have been used to identify the various structures with enhanced stellar number density (3sigma above the mean background density). About 50 large stellar groupings have been revealed showing: 1) hierarchical structure, where the smallest are found within the large ones. 2) their size distribution has peaks at 250+/-50 pc (aggregates) and 600+/-50 pc (complexes), there are also a few cases with size 1200+/-50 pc (supercomplexes). 3) there is evidence that at the fainter magnitudes these structures are aligned to a general trend whereas at the most bright end (B1, O spectral types) they become more clumpy and symmetrical in shape. The relationship between the above complexes' properties and the various scenarios of star formation are discussed.

Maragoudaki, F.; Kontizas, M.; Kontizas, E.; Dapergolas, A.; Morgan, D. H.

1998-10-01

408

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

CERN Document Server

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 &...

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

409

ATLAS ALFA-measuring absolute luminosity with scintillating fibres  

International Nuclear Information System (INIS)

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 restricted space inside the pots makes the coupling to the read out devices very challenging. Several technologies have been tested in a beam at DESY and a cosmic-ray setup at CERN. A possible upgrade of the photo detection could consist in the replacement of the PMT by Geiger-mode avalanche photodiodes. Preliminary tests are being performed comparing the performance of these devices with the ones of the PMTs.

410

Period-Luminosity Relation for Type II Cepheids  

Science.gov (United States)

We have estimated JHKs magnitudes corrected to mean intensity for LMC type II Cepheids found in the OGLE-III survey. Period-luminosity relations (PLRs) are derived in JHKs as well as in a reddening-free VI parameter. The BL Her stars (PPLR of type II Cepheids as a distance indicator by confirming that (almost) the same PLR satisfies the distributions in the PL diagram of type II Cepheids in (at least) two different systems, i.e. the LMC and Galactic globular clusters, and by calibrating the zero point of the PLR. RV Tau stars in the LMC, as a group, are not co-linear with the shorter-period type II Cepheids in the infrared PLRs in marked contrast to such stars in globular clusters. We note differences in period distribution and infrared colors for RV Tau stars in the LMC, globular clusters and Galactic field. We also compare the PLR of type II Cepheids with that of classical Cepheids.

Matsunaga, Noriyuki; Feast, Michael W.; Menzies, John W.

2009-09-01

411

Period-Luminosity Relation for Type II Cepheids  

CERN Document Server

We have estimated JHKs magnitudes corrected to mean intensity for LMC type II Cepheids found in the OGLE-III survey. Period-luminosity relations (PLRs) are derived in JHKs as well as in a reddening-free VI parameter. The BL Her stars (P<4d) and the W Vir stars (P=4 to 20d) are co-linear in these PLRs. The slopes of the infrared relations agree with those found previously for type II Cepheids in globular clusters within the uncertainties. Using the pulsation parallaxes of V553 Cen and SW Tau, the data lead to an LMC modulus of 18.46+-0.10 mag, uncorrected for any metallicity effects. We have now established the PLR of type II Cepheids as a distance indicator by confirming that (almost) the same PLR satisfies the distributions in the PL diagram of type II Cepheids in (at least) two different systems, i.e. the LMC and Galactic globular clusters, and by calibrating the zero point of the PLR. RV Tau stars in the LMC, as a group, are not co-linear with the shorter-period type II Cepheids in the infrared PLRs in ...

Matsunaga, Noriyuki; Menzies, John W

2009-01-01

412

The B band luminosities of QSO host galaxies  

CERN Document Server

We report on the analysis of B band imaging data of 57 low-redshift QSOs and Seyfert 1 galaxies selected from the Hamburg/ESO-Survey, for which host galaxy dependent selection biases are greatly reduced compared to other optical surveys. Only one object in the sample is known to be radio-loud. We adopted a procedure to remove the AGN contribution by subtracting a scaled point spread functions from each QSO image. To reclaim the integrated host galaxy flux we correct for oversubtraction based on simulations. This method shows to be quite insensitive to the host galaxy morphological type, which we can unambiguously established for 15 of the 57 objects. The quasar host galaxies are detected in all cases. The hosts are very luminous, ranging in absolute magnitude M_B from -19.0 to -23.8, with an average of M_B,gal = -21.5, considerably above L* for field galaxies. For the luminous QSO subsample with M_B < -23 the average host absolute magnitude is M_B,gal = -23.0, while for the complementary low-luminosity AGN...

Jahnke, K

2003-01-01

413

Luminosity Function of The Galaxy Cluster Abell 85  

Science.gov (United States)

Using the photometric and spectroscopic data from the NASA/IPAC Extragalactic Database (NED) and the Eighth Data Release of Sloan Digital Sky Survey (SDSS-DR8), we have studied the luminosity function (LF) of the galaxy cluster Abell 85 within the double dynamical radius 2r200. It is shown that the LF of Abell 85 can be fitted very well with a Schechter function in all the 5 SDSS wavebands, and that the LF exhibits a dip in the u, g, and z bands, respectively. The best-fitting parameters (the characteristic absolute magnitude in the r band and the slope at the faint end of the LF) of the Schechter function are ? mag, and ? for the early-type galaxies, ? mag, and ? for the late-type galaxies, respectively. The LF of early-type galaxies shows a dip at ? mag. In addition, we have also investigated the LFs in the three concentric annuli within 1.5r200, and found that the closer the distance from the cluster center, the steeper the faint-end slope, and the brighter the characteristic magnitude.

Feng, LI; Peng-fei, YAN; Qi-rong, YUAN

2014-07-01

414

Challenges on the high luminosity frontier of e+ e-  

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 (''crab-crossing''), 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

415

The Luminosity-Metallicity Relation of distant luminous infrared galaxies  

CERN Document Server

One hundred and five 15mu selected objects in three ISO deep survey fields (CFRS 3h, UDSR and UDSF) are studied on the basis of the high quality optical spectra with resolution R>1000 from VLT/FORS2. Ninety two objects (88%) have secure redshifts, ranging from 0 to 1.16 with a median value of 0.587. Considerable care is taken in estimating the extinction property of individual galaxy, which can seriously affect diagnostic diagrams and estimates of star formation rates and of metal abundances. Two independent methods have been adopted to estimate extinction, e.g. Balmer line ratio (A_V(Balmer)) and energy balance between IR and Hbeta luminosities (A_V(IR)). For most of the z>0.4 luminous IR galaxies (LIRGs), the two extinction coefficients are consistent well, with median values of A_V(IR) = 2.36. These distant LIRGs show many properties strikingly in common with those of local (IRAS) LIRGs studied by Veilleux et al. (1995). Our sample can provide a good representation of LIRGs in the distant Universe. Most (>...

Liang, Y C; Flores, H; Elbaz, D; Césarsky, C J

2004-01-01

416

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

International Nuclear Information System (INIS)

-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

417

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