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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).

2011-10-10

2

LORENTZ-FACTOR-ISOTROPIC-LUMINOSITY/ENERGY CORRELATIONS OF GAMMA-RAY BURSTS AND THEIR INTERPRETATION  

Energy Technology Data Exchange (ETDEWEB)

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta ({Gamma}{sub 0}) is a key parameter to understanding GRB physics. Liang et al. have discovered a correlation between {Gamma}{sub 0} and isotropic {gamma}-ray energy: {Gamma}{sub 0}{proportional_to}E{sup 0.25}{sub {gamma},iso,52}. By including more GRBs with updated data and more methods to derive {Gamma}{sub 0}, we confirm this correlation and obtain {Gamma}{sub 0} {approx_equal} 91E{sup 0.29}{sub {gamma},iso,52}. Evaluating the mean isotropic {gamma}-ray luminosities L{sub {gamma},iso} of the GRBs in the same sample, we discover an even tighter correlation {Gamma}{sub 0} {approx_equal} 249L{sup 0.30}{sub {gamma},iso,52}. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive {Gamma}{sub 0}{proportional_to}L{sup 0.22}{sub {gamma},iso}, which is consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.

Lue Jing; Zou Yuanchuan; Lei Weihua; Wu Qingwen; Wang Dingxiong [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhang Bing; Lue Houjun [Department of Physics and Astronomy, University of Nevada Las Vegas, 4505 Maryland Parkway, Box 454002, Las Vegas, NV 89154-4002 (United States); Liang Enwei, E-mail: zouyc@hust.edu.cn, E-mail: leiwh@hust.edu.cn, E-mail: zhang@physics.unlv.edu [Department of Physics, Guangxi University, Nanning 530004 (China)

2012-05-20

3

LORENTZ-FACTOR–ISOTROPIC-LUMINOSITY/ENERGY CORRELATIONS OF GAMMA-RAY BURSTS AND THEIR INTERPRETATION  

International Nuclear Information System (INIS)

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (?0) is a key parameter to understanding GRB physics. Liang et al. have discovered a correlation between ?0 and isotropic ?-ray energy: ?0?E0.25?,iso,52. By including more GRBs with updated data and more methods to derive ?0, we confirm this correlation and obtain ?0 ? 91E0.29?,iso,52. Evaluating the mean isotropic ?-ray luminosities L?,iso of the GRBs in the same sample, we discover an even tighter correlation ?0 ? 249L0.30?,iso,52. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive ?0?L0.22?,iso, which is consistent with the data. This suggests that the central engine of long GRBs is likely a stellar mass black hole surrounded by a hyper-accreting disk.

2012-05-20

4

Lorentz Factor-Isotropic Luminosity/Energy Correlations of GRBS and Their Interpretation  

CERN Document Server

The bulk Lorentz factor of the gamma-ray burst (GRB) ejecta (Gamma_0) is a key parameter to understand the GRB physics. Liang et al. have discovered a correlation between Gamma_0 and isotropic gamma-ray energy: Gamma_0\\proptoE_{gamma,iso,52}^{0.25}. By including more GRBs with updated data and more methods to derive Gamma_0, we confirm this correlation and obtain Gamma_0~118E_{gamma,iso,52}^{0.26}. Evaluating the mean isotropic gamma-ray luminosities L_{gamma,iso} of the GRBs in the same sample, we discover an even tighter correlation Gamma_0~264 L_{gamma,iso,52}^{0.27}. We propose an interpretation to this later correlation. Invoking a neutrino-cooled hyperaccretion disk around a stellar mass black hole as the central engine of GRBs, we derive jet luminosity powered by neutrino annihilation and baryon loading from a neutrino-driven wind. Applying beaming correction, we finally derive Gamma_0\\proptoL_{gamma,iso}^{0.22}, which is well consistent with the data. This suggests that the central engine of long GRBs...

Lv, Jing; Lei, Wei-Hua; Zhang, Bing; Wu, Qing-Wen; Wang, Ding-Xiong; Liang, En-Wei; Lv, Hou-Jun

2011-01-01

5

Luminosity monitor  

International Nuclear Information System (INIS)

Luminosity monitors are needed in each experiment doing spin physics at RHIC. They concentrate on the luminosity aspects here because, for example, with a 10-3 raw asymmetry in an experiment, an error of 10-4 in the luminosity is as significant as a 10% polarization error. Because luminosity is a property of how two beams overlap, the luminosity at an interaction region must be measured at that interaction region in order to be relevant to the experiment at that interaction region. The authors will have to do the physics and the luminosity measurements by using labels on the event sums according to the polarization labels on the colliding bunches. Most likely they will not have independent polarization measurement on each bunch, but only on all the filled bunches in a ring, or perhaps all the bunches that are actually used in an experiment. Most analyses can then be handled by using the nine combinations gotten from three kinds of bunches in each ring, +, - and empty bunches. The empty bunches are needed to measure beam-gas background, (and some, like six in a row, are needed for the beam abort). Much of the difficulty comes from the fact that they must use a physics process to represent the luminosity. This process must have kinematic and geometric cuts both to reduce systematics such as beam-gas backgrounds, and to make it representative of the part of the interaction diamond from which the physics events come.

1998-01-01

6

Luminosity monitor.  

Energy Technology Data Exchange (ETDEWEB)

Luminosity monitors are needed in each experiment doing spin physics at RHIC. They concentrate on the luminosity aspects here because, for example, with a 10{sup {minus}3} raw asymmetry in an experiment, an error of 10{sup {minus}4} in the luminosity is as significant as a 10% polarization error. Because luminosity is a property of how two beams overlap, the luminosity at an interaction region must be measured at that interaction region in order to be relevant to the experiment at that interaction region. The authors will have to do the physics and the luminosity measurements by using labels on the event sums according to the polarization labels on the colliding bunches. Most likely they will not have independent polarization measurement on each bunch, but only on all the filled bunches in a ring, or perhaps all the bunches that are actually used in an experiment. Most analyses can then be handled by using the nine combinations gotten from three kinds of bunches in each ring, +, {minus} and empty bunches. The empty bunches are needed to measure beam-gas background, (and some, like six in a row, are needed for the beam abort). Much of the difficulty comes from the fact that they must use a physics process to represent the luminosity. This process must have kinematic and geometric cuts both to reduce systematics such as beam-gas backgrounds, and to make it representative of the part of the interaction diamond from which the physics events come.

Underwood, D. G.

1998-07-16

7

Luminosity Upgrades for ILC  

CERN Multimedia

The possibility of increasing the luminosity for the ILC at Ecm < 350 GeV centre-of-mass by increasing the beam power are considered. It will be shown that an approximately constant luminosity can be achieved across the centre of mass energy range (250-500 GeV) without exceeding the installed AC power for 500 GeV operation. Overall a factor of four in luminosity over the published baseline could be achieved at 250 GeV resulting in 3*10**34 cm-2s-1. The implications for the damping rings and positron source are also briefly discussed.

Harrison, Mike; Walker, Nicholas

2013-01-01

8

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

9

Luminosity Lifetime  

Energy Technology Data Exchange (ETDEWEB)

In a symmetric or 'energy transparent' relativistic collider, the luminosity is given by L = N{sup 2}f{sub c}/4{pi}{sigma}*{sub x}{sigma}*{sub y} where N is the number of electrons or positrons per bunch, {sigma}*{sub x} ({sigma}*{sub y}) is the horizontal (vertical) rms beam size at the interaction point (IP), and f{sub c} is the collision frequency. If the beam sizes remain constant as the luminosity decreases, then the time dependence of luminosity is contained entirely in the time dependence of the beam currents, i.e., N O N(t), and we can rewrite the equation as L(t) = N{sup 2}(t)f{sub c}/4{pi}{sigma}*{sub x}{sigma}*{sub y}. There are two distinct categories for luminosity loss. In the first category are loss processes due to collisions between the two beams, that is, processes associated directly with the luminosity. In the second category (see below) are single-beam loss processes. The processes in the first category relevant to a high-energy collider are Bhabha scattering (e{sup +}e{sup -} O e{sup +}e{sup -}) and 'radiative' Bhabha scattering (e{sup +}e{sup -} O e{sup +}e{sup -}{gamma}). In the first process, a beam particle is lost if its angular deflection is beyond the ring's transverse acceptance; in the second process, loss occurs if the beam particle's momentum change is outside the longitudinal acceptance of the ring (typically determined by the RF bucket height).

Zisman, M.S.

1997-04-01

10

RHIC LUMINOSITY UPGRADE PROGRAM  

Energy Technology Data Exchange (ETDEWEB)

The Relativistic Heavy Ion Collider (RHIC) operates with either ions or polarized protons. After increasing the heavy ion luminosity by two orders of magnitude since its commissioning in 2000, the current luminosity upgrade program aims for an increase by another factor of 4 by means of 3D stochastic cooling and a new 56 MHz SRF system. An Electron Beam Ion Source is being commissioned that will allow the use of uranium beams. Electron cooling is considered for collider operation below the current injection energy. For the polarized proton operation both luminosity and polarization are important. In addition to ongoing improvements in the AGS injector, the construction of a new high-intensity polarized source has started. In RHIC a number of upgrades are under way to increase the intensity and polarization transmission to 250 GeV beam energy. Electron lenses will be installed to partially compensate the head-on beam-beam effect.

Fischer, W.

2010-05-23

11

The OLYMPUS Luminosity Monitors  

Science.gov (United States)

The OLYMPUS experiment at DESY has been proposed to measure the ratio of positron-proton and electron-proton elastic scattering cross sections to quantify the effect of two-photon exchange, 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, precise monitoring of the luminosities is required and will be achieved by measuring the elastic count rates at forward angles and low momentum transfer with tracking telescopes based on GEM (Gas Electron Multiplier) technology. Simulation results for the design and performance of the OLYMPUS luminosity monitors will be presented. )

Ates, Ozgur

2010-02-01

12

UPGRADING RHIC FOR HIGHER LUMINOSITY.  

Energy Technology Data Exchange (ETDEWEB)

While RHIC has only just started running for its heavy ion physics program, in the first run last summer, we achieved 10% of the design luminosity. In this paper we discuss plans for increasing the luminosity by a factor of 35 beyond the nominal design. A factor of 4 should be straightforward by doubling the number of bunches per ring and squeezing the {beta}* from 2 to 1 m at selected interaction points. An additional factor of 8 to 10 could be possible by using electron cooling to counteract intrabeam scattering and reduce emittances of the beams.

MACKAY,W.; BEN-ZVI,I.; BRENNAN,J.M.; HARRISON,M.; KEWISCH,J.; PEGGS,S.; ROSER,T.; TRBOJEVIC,D.; PARKHOMCHUK,V.

2001-06-18

13

The Eddington Luminosity Limit for Multiphased Media  

UK PubMed Central (United Kingdom)

We consider the effective Eddington luminosity in a locally inhomogeneousmedium by averaging out the coarse, small scale behavior. We show that theratio between the emitted flux and the average radiation force changes. Themean luminosity can therefore theoretically exceed the classical Eddington limit.It is further shown that acoustic modes are unstable under most relevantconditions, and they unavoidably grow in such a way that they change theeffective limiting Eddington luminosity. The instability and the increased limitingluminosity can explain the observed super Eddington luminosity phenomenon innovae.Subject headings: Radiative transfer --- novae, cataclysmic variablesTo Appear in ApJ Letters1. Introduction: The Specific Astrophysical Problem and Set-upThe best studied example of systems exhibiting super Eddington luminosities isundoubtedly novae. These stars increase their luminosities by factors of 104or more withina few hours and stay in this peak luminosity f...

Nir J. Shaviv

14

Luminosity monitor at PEP  

Energy Technology Data Exchange (ETDEWEB)

The luminosity monitor system utilized by the MKII Detector and by the PEP operators is described. This system processes information from 56 photomultipliers and calculates independent luminosities for each of the 3 colliding bunches in PEP. Design considerations, measurement techniques, and sources of error in the luminosity measurement are discussed.

Fox, J.D.; Franklin, M.E.B.

1981-02-01

15

ISR Superconducting High luminosity Insertion  

CERN Multimedia

The picture shows two of the eight superconducting quadrupoles of the low-beta insertion at intersection I8.The increase of luminosity produced by this insertion was above a factor 7. At right one can also see the Open- Axial- Field Magnet. The person is Stephan Pichler. See also 7702690X, 8102123, 8010397, 8008332.

1981-01-01

16

A Luminosity Calorimeter for CLIC  

CERN Multimedia

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

17

Variations in solar luminosity  

International Nuclear Information System (INIS)

The roles of evolution and episodic mixing in determining the solar luminosity are discussed. The influence of perturbations in the convection zone on the luminosity is reviewed in detail, showing that the efficiency of convection has significant effects on both the luminosity and the radius. The amplitude of the change is strongly dependent on the time scale of the perturbation. In the superadiabatic zone and photosphere, the effects of local suppression of convection efficiency are visible in the form of sunspots. Empirical data on solar irradiance obtained from space-borne radiometers have demonstrated the effect of sunspots on irradiance and have led to the tentative conclusion that the flux blocked by the spots is stored for very long times. 210 references

1983-01-01

18

Luminosity determination at the Tevatron  

CERN Document Server

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

Papadimitriou, Vaia

2011-01-01

19

The luminosity dependence of clustering  

CERN Document Server

The PSCz redshift survey and the ongoing Two-Degree Field Galaxy Redshift Survey (2dFGRS) are used to look for luminosity dependence of galaxy clustering by measuring the two point correlation functions for sub-samples of the surveys. An analysis of the PSCz survey finds that galaxies with cooler colours are more strongly clustered than warmer galaxies. Between 1 and 10 Mpc/h it is found that the redshift-space correlation function, is a factor of about 1.5 larger for the cooler galaxies. This is consistent with the suggestion that hotter galaxies have higher star formation rates and correspond to later type galaxies which are known to be less clustered than earlier types. There is a very weak luminosity dependence of clustering with the more luminous galaxies being less clustered than fainter galaxies, but the trend has a low statistical significance. Results from the 2dFGRS reveal a strong dependence of clustering on intrinsic galaxy luminosity. The most luminous galaxies are more strongly clustered by a fa...

Hawkins, E

2001-01-01

20

High luminosities at LEP  

Energy Technology Data Exchange (ETDEWEB)

This paper summarizes the conclusions of a CERN study on the feasibility and physics potential of operating the Large Electron Positron (LEP) collider at higher luminosity. The emphasis of the study was the feasibility of a 36-bunch scheme operating at peak of the Z resonance, which would produce about 10{sup 8} Zs in a three year run. The possibility of operating LEP with 8 bunches above the W{sup +}W{sup {minus}} threshold, where any increase in luminosity would be of great value, was also considered.

Blucher, E.C. [CERN, Geneva (Switzerland). PPE Division

1992-12-31

 
 
 
 
21

CLIC Luminosity Monitoring  

CERN Multimedia

The CLIC post-collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14 MW to the main beam dump. Luminosity monitoring for CLIC is based on high energy muons produced by beamstrahlung photons in the main dump. Threshold Cherenkov counters are proposed for the detection of these muons. The expected rates and layout for these detectors is presented. Another method for luminosity monitoring is to directly detect the beamstrahlung photons in the post-collision line. Full Monte Carlo simulation has been performed to address its feasibility.

Apyan, Armen; Gschwendtner, Edda; Lefevre, Thibault; Tygier, Sam; Appleby, Robert B

2012-01-01

22

A luminosity model of RHIC gold runs  

Energy Technology Data Exchange (ETDEWEB)

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

Zhang, S.Y.

2011-11-01

23

Luminosity Determination for  

UK PubMed Central (United Kingdom)

The integrated luminosities of the R scan data collected atps = 3:55and 2:6 GeV in 1998 spring running by BES detector operated at BEPCare measured via an analysis of the large angle Bhabha events. The resultsare L = 199:7 Sigma 2:4 Sigma 5:3nbGamma1and L = 286:4 Sigma 2:2 Sigma 7:6nbGamma1, forps = 3:55and 2:6 GeV data sets respectively, where the first error is the statistical,and the second one systematic.1

Yuan Changzheng

24

Achieving high luminosity in the Fermilab Tevatron  

International Nuclear Information System (INIS)

Fermilab has embarked upon a program, christened Fermilab III, to raise the luminosity in the Tevatron proton-antiproton collider over the next five years by at least a factor of thirty beyond the currently achieved level of 1.6x1030cm-2sec-1. Components of the program include implementation of electrostatic separators, Antiproton Source improvements, installation of cold compressors, doubling the existing linac output energy, and the construction of a new accelerator--the Fermilab Main Injector. Basic limitations in the achievement of higher luminosity in the Tevatron, the strategy developed to achieve the Fermilab III goals, and the evolution of luminosity throughout the period will be discussed. 1 fig., 2 tabs

1991-01-01

25

Luminosity measurement at ILC  

Science.gov (United States)

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

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

2013-08-01

26

Luminosity measurement in H1  

International Nuclear Information System (INIS)

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.

2011-06-01

27

The properties and luminosity function of extremely low luminosity galaxies  

CERN Document Server

We examine a sample of low redshift (10 < d < 150 Mpc) galaxies including galaxies with r-band absolute magnitudes as faint as -12.5 (for h=1), selected from the Sloan Digital Sky Survey Data Release 2 (SDSS). The sample is unique in containing galaxies of extremely low luminosities in a wide range of environments, selected with uniform and well-understood criteria. We present the luminosity function as well as the broad-band properties of low luminosity galaxies in this sample. A Schechter function is an insufficient parameterization of the r-band luminosity function; there is an upturn in the slope at low luminosities. The resulting slope at low luminosities in this sample is around -1.3. However, we almost certainly miss a large number of galaxies at very low luminosities due to low surface brightness selection effects, and we estimate that the true low luminosity slope may be as steep or steeper than -1.5. The results here are consistent with previous SDSS results and, in the g-band, roughly consist...

Blanton, M R; Schlegel, D J; Strauss, M A; Brinkmann, J; Fukugita, M; Loveday, J; Blanton, Michael R.; Lupton, Robert H.; Schlegel, David J.; Strauss, Michael A.; Fukugita, Masataka; Loveday, Jon

2004-01-01

28

Luminosity function of GRBs  

CERN Multimedia

The luminosity function (LF) statistics applied to the BATSE GRBs (sources of GUSBAD catalog) is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, where the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We applied the tool of the LF statistics to three GRB classes predicted by the Fireshell model. One of the main differences between the Fireshell and Fireball models is the explanation of the GRB prompt emission, where the first claims that it is divided in two physical processes: 1) transparency of a optically thick Freshell producing the P-GRB emission and 2) interaction of a relativistic shell (composed by baryons electron-positron-photon) against the CBM (circumburst medium), producing the emission so-called extended afterglow peak (EAP). However, the Fireball model, the most quoted one, claims that the prompt emission is caused by interactions among several rela...

Lemos, L J Rangel; Ruffini, R; Malheiro, M

2013-01-01

29

High luminosity muon collider design  

International Nuclear Information System (INIS)

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 ?+?- collider, and of a 0.5 TeV lower luminosity demonstration machine. We discuss the various systems in such muon colliders.

1996-01-01

30

Luminosity measurement in H1  

International Nuclear Information System (INIS)

At HERA, luminosity is determined on-line and bunch by bunch by measuring the Bremsstrahlung spectrum from e-p collisions. The Hl collaboration has built a completely new luminosity system in order to sustain the harsh running conditions after the fourfold luminosity increase. Namely, the higher synchrotron radiation doses and the increased event pile-up have governed the design of the two major components, a radiation resistant quartz-fibre electro-magnetic calorimeter, and a fast read-out electronic with on-line energy histogram loading at a rate of 500 kHz. The group was in charge of the electronic and the on-line data analysis of the new luminosity system. In this thesis, I present analysis tools and methods to improve the precision of the luminosity measurement. The energy scale and acceptance calculation methods set out in this thesis permit these values to be determined every four minutes, to an accuracy of 0.5 parts per thousand for the energy scale and 2 parts per thousand for the acceptance. From these results, the degree of accuracy obtained on the luminosity measurement is between 6.5 and 9.5 parts per thousand. These results are currently undergoing validation, with the aim of becoming the standard H1 method. I also studied quasi-elastic Compton events to cross-check the luminosity measurement using the 2003- 2004 and 2005 data. Indeed, this process has a well calculable cross section and a clear experimental signature. The leptonic final state consists of a coplanar e-gamma system, both observable in the central H1 detector. (author)

2006-01-01

31

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; Cíntia Monteiro; Maria Angélica Sorgini Peterlini; Mavilde da Luz Gonçalves Pedreira

2010-01-01

32

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

Scientific Electronic Library Online (English)

Full Text Available Abstract in portuguese 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 demonstra (more) ram variações que não ultrapassaram 1,0 valor de pH e que alguns antimicrobianos, eminentemente ácidos após a diluição, mantiveram esse comportamento em todas as situações estudadas, não sugerindo a influência de fatores ambientais no comportamento químico das soluções. Como alguns valores de pH encontrados podem contribuir para o desenvolvimento de flebite química e infiltração, é importante enfatizar para a prática clínica em saúde, a necessidade de conhecer as características das soluções de infusão intravenosa, considerando tipo de diluição e tempo de infusão. Abstract in spanish El objetivo de este estudio experimental fue medir el pH de los antibióticos de administración intravenosa ceftriaxona sódica, clorhidrato de vancomicina, metronidazol, penicilina G potásica y sulfato de amikacina, después de reconstitución con agua destilada y dilución con NaCl a 0,9%, o suero 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. (more) Los resultados demostraron variaciones que no ultrapasaron 1,0 (valor de pH) y que algunos antimicrobianos, eminentemente ácidos después de la dilución, mantuvieron ese comportamiento en todas las situaciones estudiadas, no sugiriendo la influencia de factores ambientales en el comportamiento químico de las soluciones. Considerando que algunos valores de pH encontrados pueden contribuir para el desarrollo de flebitis química e infiltración, es importante enfatizar que para la práctica clínica en salud, existe la necesidad de conocer las características de las soluciones de infusión intravenosa, considerando el tipo de dilución y el tiempo de infusión. Abstract in english The objective of this experimental study was to measure the pH of antibiotics administered by intravenous infusion - ceftriaxone sodium, vancomycin hydrochloride, metrodinazole, penicillin G potassium and amikacin sulfate - after reconstitution with sterile water and dilution with NaCl 0.9% or 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 antibiotic (more) s 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.

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

2010-04-01

33

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

CERN Document Server

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

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

2011-01-01

34

Luminosity of comoving particle collisions  

CERN Multimedia

New type of particle collisions for fusion experiments with unstable nucleus is considered. In a comoving interaction scheme two beams propagate on-axis in the same direction with different velocities. Small difference in particle velocities provides the low interaction energy required for study of nuclear fusion processes. The paper analyses conditions to obtain a high value of luminosity.

Parkhomchuk, V V; Katayama, T

2000-01-01

35

The Globular Cluster Luminosity Function  

CERN Document Server

The main aspects of the globular cluster luminosity function needing to be explained by a general theory of cluster formation are reviewed, and the importance of simultaneously understanding globular cluster systematics (the fundamental plane) within such a theory is pointed out.

McLaughlin, D E

2003-01-01

36

Deriving the Quasar Luminosity Function from Accretion Disk Instabilities  

UK PubMed Central (United Kingdom)

We have derived the quasar luminosity function assuming that the quasar activityis driven by a thermal-viscous unstable accretion disk around a supermassive blackhole. The instabilities produce large amplitude, long-term variability of a single source.We take a light curve of a single source and calculate the luminosity function, fromthe function of time it spends at each luminosity. Convolving this with an assumedmass distribution we fit well the observed optical luminosity function of quasars at fourredshifts. As a result we obtain the evolution of the mass distribution between redshifts2.5 and 0.5.The main conclusions are following: 1) The quasar long-term variability due to thedisk thermal-viscous instabilities provides a natural explanation for the observed quasarluminosity function. 2) The peak of the mass function evolves towards lower black holemasses at lower redshifts by a factor ¸ 10. 3) High mass sources die subsequently whenredshift gets smaller. 4) The number ...

Aneta Siemiginowska; Martin Elvis

37

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

38

Updating quasar bolometric luminosity corrections  

CERN Multimedia

Bolometric corrections are used in quasar studies to quantify total energy output based on a measurement of a monochromatic luminosity. First, we enumerate and discuss the practical difficulties of determining such corrections, then we present bolometric luminosities between 1 \\mu m and 8 keV rest frame and corrections derived from the detailed spectral energy distributions of 63 bright quasars of low to moderate redshift (z = 0.03-1.4). Exploring several mathematical fittings, we provide practical bolometric corrections of the forms L_iso=\\zeta \\lambda L_{\\lambda} and log(L_iso)=A+B log(\\lambda L_{\\lambda}) for \\lambda= 1450, 3000, and 5100 \\AA, where L_iso is the bolometric luminosity calculated under the assumption of isotropy. The significant scatter in the 5100 \\AA\\ bolometric correction can be reduced by adding a first order correction using the optical slope, \\alpha_\\lambda,opt. We recommend an adjustment to the bolometric correction to account for viewing angle and the anisotropic emission expected fr...

Runnoe, Jessie C; Shang, Zhaohui

2012-01-01

39

Detectors and luminosity for hadron colliders  

Energy Technology Data Exchange (ETDEWEB)

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.

Diebold, R.

1982-01-01

40

Missing mass from low-luminosity stars  

Energy Technology Data Exchange (ETDEWEB)

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.

Hawkins, M.R.S.

1986-12-17

 
 
 
 
41

Periods, amplitudes, and luminosities of red supergiants  

Energy Technology Data Exchange (ETDEWEB)

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.

Abramian, G.V.

1984-09-01

42

Symmetric Moeller/Bhabha Luminosity Monitor  

Energy Technology Data Exchange (ETDEWEB)

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

Perez Benito, Roberto [Helmholtz-Institut Mainz, Johannes Gutenberg-Universitaet, Johann-Joachim-Becher-Weg 45, 55128 Mainz (Germany); Collaboration: OLYMPUS-Collaboration

2011-07-01

43

Magnetic spectrograph with high luminosity  

International Nuclear Information System (INIS)

[en] A magnetic spectrograph used to study nuclear reactions at low-energy incident particles is described. The spectrograph high luminosity intensity of 9x10-3 mm2 steradians makes it possible to obtain charged particle energy spectra for a relatively short time. Energy resolution as applied to protons (E/?E is about 600) is practically constant within the whole energy range of the spectrograph E max/E min is equal to 1.45. The luminosity is equal to 4.5x10-4 steradians. The main characteristics of the spectrograph are compared to those of two other ones used to study d,p reactions. The angular distribution of reaction products is ensured by the use of a system of magnets bending the particle beam incident on the target along the direction of registering. Selection of currents in the magnets assures the reaction product registration at any angle from 10 to 150 deg in a step of 10 deg. The magnet lay-out scheme is presented, spectra are shown for deuterons, alpha-particles and protons from the 27Al(d,p) 28Al reaction at the deuteron energy of 3.6 MeV obtained with the spectrograph described

1974-01-01

44

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

45

Prospects for the ATLAS upgrade for the high luminosity LHC  

CERN Document Server

The Large Hadron Collider (LHC) will continue to be the main infrastructure for experimental High Energy Physics. To maintain the physics potential of LHC, a series of upgrade will be required to increase the yearly integrated luminosity by a factor 10 compared to the original design value. ATLAS will need to correspondingly upgrade its detectors, triggers and data acquisition systems. The aim is to be able to maintain a high efficiency for Standard Model and Beyond Standard Model signals despite a much difficult environment caused by the increasing number of pileup from the high luminosity. This presentation will cover the prospects for the ATLAS upgrade for the high luminosity LHC and present the various planned detector upgrades and their effect on the performance.

Brenner, R; The ATLAS collaboration

2013-01-01

46

Operation of the LHC at High luminosity and High stored energy  

CERN Document Server

In 2011 the operation of the Large Hadron Collider LHC entered its first year of high luminosity production at a beam energy of 3.5 TeV. In the first months of 2011 the number of bunches was progressively increased to 1380, followed by a reduction of the transverse emittance, an increase of the bunch population and a reduction of the betatron function at the collision points. The performance improvements steps that were accumulated in 2011 eventually brought the peak luminosity to 3.6 × 1033cm?2s?1. The integrated luminosity delivered to each of the high luminosity experiments amounted to 5.6 fb?1, a factor of 5 above the initial target defined in 2010. The operational experience with high intensity and luminosity at the LHC will be presented, together with the issues that had to be tackled on the road to high intensity and luminosity.

Wenninger, J; Arduini, G; Assmann, R; Holzer, B; Holzer, EB; Kain, V; Lamont, M; Macpherson, A; Papotti, G; Pojer, M; Ponce, L; Redaelli, S; Solfaroli Camillocci, M; Uythoven, J; Venturini Delsolaro, W

2012-01-01

47

Luminosity monitoring and calibration of BLM  

Science.gov (United States)

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

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

2011-01-01

48

Luminosity Spectrum Reconstruction at Linear Colliders  

CERN Document Server

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

Poss, Stéphane

2013-01-01

49

Differential Luminosity Measurement using Bhabha Events  

CERN Document Server

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

Poss, Stephane

2013-01-01

50

The Local Galaxy 8 micron Luminosity Function  

CERN Multimedia

A SST survey in the NOAO Deep-Wide Field in Bo\\"otes provides a complete, 8-micron-selected sample of galaxies to a limiting (Vega) magnitude of 13.5. In the 6.88 deg$^2$ field sampled, 79% of the 4867 galaxies have spectroscopic redshifts, allowing an accurate determination of the local (z<0.3) galaxy luminosity function. Stellar and dust emission can be separated on the basis of observed galaxy colors. Dust emission (mostly PAH) accounts for 80% of the 8 micron luminosity, stellar photospheres account for 19%, and AGN emission accounts for roughly 1 %. A sub-sample of the 8 micron-selected galaxies have blue, early-type colors, but even most of these have significant PAH emission. The luminosity functions for the total 8 micron luminosity and for the dust emission alone are both well fit by Schechter functions. For the 8 micron luminosity function, the characteristic luminosity is \

Huang, J -S; Barmby, P; Brodwin, M; Brown, M J I; Caldwell, N; Cool, R J; Eisenhardt, P; Eisenstein, D; Fazio, G G; Le Floc'h, E; Green, P; Kochanek, C S; Lu, N Y; Pahre, M A; Rigopoulou, D; Rosenberg, J L; Smith, H A; Wang, Z; Willmer, C N A; Willner, S P

2007-01-01

51

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

52

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

53

Luminosity of young Jupiters revisited. Massive cores make hot planets  

CERN Multimedia

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

54

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

55

Characterizing Luminosity Evolution in the Tevatron.  

Science.gov (United States)

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 expo...

V. Shiltsev E. McCrory

2004-01-01

56

Detectors and luminosity for hadron colliders  

International Nuclear Information System (INIS)

[en] 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

1982-01-01

57

The QSO variability-luminosity-redshift relation  

CERN Multimedia

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

58

Luminosity Monitoring in ATLAS with MPX Detectors  

CERN Multimedia

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.

The ATLAS collaboration

2013-01-01

59

The luminosity monitor of Beijing spectrometer  

International Nuclear Information System (INIS)

A luminosity monitor (LM) was constructed at Beijing Electron Positron Collider (BEPC) responsible for measuring the colliding luminosity of BEPC. Being a part of the Beijing spectrometer (BES), which is a large major detector of the BEPC, the LM is also capable of providing the integrated luminosity for physics study in BES. By various means, such as fine design and careful manufacture of various counters, precise positioning of the LM, employing multifold and delay coincidences, etc., the LM is able to measure a relatively precise luminosity with a significantly suppressed background, e.g. the first colliding of BEPC in 1988 was detected and announced in time by the LM with a luminosity of 5x1028/cm2 s. Besides, some useful information was provided by the LM to assist the proper operation of the BEPC. In this paper, the construction, operation, experimental results and the error analysis of the LM are presented in detail. (orig.).

1993-01-01

60

A fast luminosity monitor for BEPCII  

Science.gov (United States)

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

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

2010-04-01

 
 
 
 
61

Galaxy correlations and the luminosity function  

International Nuclear Information System (INIS)

Given the simple assumption that any excess of correlated galaxies seen close on the sky to a galaxy of known distance are also at the same distance, a galaxy luminosity function can be determined from the variation in excess number with magnitude. Averaged over many 'centre' galaxies this luminosity function has good statistical accuracy at the faint end compared to the usual direct estimation from magnitude-limited surveys since the latter necessarily contain few intrinsically faint objects. The form of the luminosity function found from recent redshift surveys is confirmed. (author).

1987-01-01

62

Galaxy correlations and the luminosity function  

Energy Technology Data Exchange (ETDEWEB)

Given the simple assumption that any excess of correlated galaxies seen close on the sky to a galaxy of known distance are also at the same distance, a galaxy luminosity function can be determined from the variation in excess number with magnitude. Averaged over many 'centre' galaxies this luminosity function has good statistical accuracy at the faint end compared to the usual direct estimation from magnitude-limited surveys since the latter necessarily contain few intrinsically faint objects. The form of the luminosity function found from recent redshift surveys is confirmed.

Phillipps, S.; Shanks, T.

1987-07-01

63

Characterizing luminosity evolution in the Tevatron  

Energy Technology Data Exchange (ETDEWEB)

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.

Shiltsev, V.; McCrory, E.; /Fermilab

2005-05-01

64

Luminosity determination at HERA-B  

CERN Document Server

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.

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

2007-01-01

65

Luminosity determination at HERA-B  

International Nuclear Information System (INIS)

[en] 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.)

2007-01-01

66

The performance of the CDF luminosity monitor  

CERN Multimedia

We describe the initial performance of the detector used for the luminosity measurement in the CDF experiment in Run II at the Tevatron. The detector consists of low-mass gaseous Cherenkov counters with high light yield (approx 100 photoelectrons) and monitors the process of inelastic pp-bar scattering. It allows for several methods of precise luminosity measurements at peak instantaneous luminosities of 2x10 sup 3 sup 2 cm sup - sup 2 s sup - sup 1 , corresponding to an average of six pp-bar interactions per bunch crossing.

Acosta, D; Konigsberg, J; Korytov, A; Mitselmakher, G; Necula, V; Nomerotski, A; Pronko, A; Sukhanov, A; Safonov, A; Tsybychev, D; Wang, S M; Wong, M

2002-01-01

67

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

68

Luminosity measurement with the CLEO II detector  

Energy Technology Data Exchange (ETDEWEB)

A measurement of absolute integrated luminosity is presented using the CLEO II detector operating at the CESR e[sup +]e[sup -] storage ring. Independent analyses of three different final states (e[sup +]e[sup -], [gamma][gamma], and [mu][sup +][mu][sup -]) at [radical](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.))

Crawford, G. (Ohio State University, Columbus, Ohio 43210 (United States)); Daubenmier, C.M. (Ohio State University, Columbus, Ohio 43210 (United States)); Fulton, R. (Ohio State University, Columbus, Ohio 43210 (United States)); Fujino, D. (Ohio State University, Columbus, Ohio 43210 (United States)); Gan, K.K. (Ohio State University, Columbus, Ohio 43210 (United States)); Honscheid, K. (Ohio State University, Columbus, Ohio 43210 (United States)); Kagan, H. (Ohio State University, Columbus, Ohio 43210 (United States)); Kass, R. (Ohio State University, Columbus, Ohio 43210 (United States)); Lee, J. (Ohio State University, Columbus, Ohio 43210 (United States)); Malchow, R. (Ohio State University, Columbus, Ohio 43210 (United States)); Skovpen, Y. (Ohio State University, Columbus, Ohio 43210 (United States)); Sung, M. (Ohio State University, Columbus, Ohio 43210 (United States)); White, C. (Ohio State University, Columbus, Ohio 43210 (United States)); Butler, F. (University; CLEO Collaboration

1994-07-01

69

Luminosity considerations: head-on collisions  

International Nuclear Information System (INIS)

For true head-on collisions, measuring luminosity appears to be straightforward. Small crossing angles, even if they work, complicate the situation very much--especially if one wishes to know the luminosity better than 10 percent. However, except for the possible necessity of some extra trim magnets, it is hard to see how these considerations can affect the design of the energy doubler/saver (ED/S) collider in a significant way. If true head-on collisions are implemented, a monitor of luminosity and interaction region location can be placed away from the experiment. For small angle crossings, the experimenters have to include such facilities in their experimental design

1976-01-01

70

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

71

ISR Superconducting High-Luminosity (low beta ) insertion  

CERN Document Server

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

72

Luminosity function and density field of the Sloan and Las Campanas Redshift Survey  

CERN Multimedia

The luminosity function of galaxies of the Early Data Release of the Sloan Digital Sky Survey (SDSS) and the Las Campanas Redshift Survey (LCRS) is calculated. The luminosity function depends on redshift, density of the environment and is different for the Norther and Southern slice of SDSS. Luminosity functions is used to derive the number and luminosity density fields of galaxies of the SDSS and LCRS surveys with a grid size of 1 h^{-1} Mpc for flat cosmological models with \\Omega_m=0.3 and \\Omega_\\Lambda =0.7. We find that the luminosity function depends on the density of the environment: in high-density regions brightest galaxies are more luminous than in low-density regions by a factor up to 5.

Hütsi, G; Tucker, D L; Saar, E; Einasto, M; Müller, V; Heinämäki, P; Allam, S S

2002-01-01

73

Luminosity increasing in the PETRA storage ring  

Energy Technology Data Exchange (ETDEWEB)

To improve the beam luminosity of PETRA storage ring, introduced are sections with the minimal ..beta..-function value of the focusing quadrupoles. The sections are intended for compressing the beam in four regions of interaction. The beam lifetime has not shortened, other parameters have remained the same, whereas the luminosity has in-- creased three times. The solution found allowed one to completely exclude the compensating coils and install new quadrupoles.

1982-01-01

74

Luminosity Optimization Feedback in the SLC  

International Nuclear Information System (INIS)

[en] 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

1999-01-01

75

Luminosity-Dependent Quasar Lifetimes: Reconciling the Optical and X-ray Quasar Luminosity Functions  

CERN Multimedia

We consider implications of our new model of quasar lifetimes and light curves for the quasar luminosity function (LF) at different frequencies and redshifts. In our picture, quasars evolve rapidly and the lifetime depends on both their instantaneous and peak luminosities. The bright end of the LF traces the peak intrinsic quasar activity, but the faint end consists of quasars which are either undergoing exponential growth to much larger masses and luminosities, or are in sub-Eddington quiescent states going into or coming out of a period of peak activity. The 'break' in the observed LF corresponds directly to the maximum in the intrinsic distribution of peak luminosities, which falls off at both brighter and fainter luminosities. We study this model using simulations of galaxy mergers which successfully reproduce a wide range of observed quasar phenomena, including the observed column density distribution. By combining quasar lifetimes and the distribution of maximum quasar luminosities determined from the o...

Hopkins, P F; Cox, T J; Matteo, T D; Robertson, B; Springel, V; Hopkins, Philip F.; Hernquist, Lars; Cox, Thomas J.; Matteo, Tiziana Di; Robertson, Brant; Springel, Volker

2005-01-01

76

Absolute luminosity measurement at LHCb with beam-gas imaging  

CERN Document Server

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. A gas injection device (SMOG) has been installed in the LHCb experiment to increase the pressure around the interaction point during dedicated fills. The Beam-Gas Imaging method (BGI) has now the potential to surpass the accuracy of the commonly used *van der Meer scan* method (VDM). The technique has been used in 10 LHC fills during 2012 including and also provided a first luminosity measurement for proton-lead collisions. This talk presents the principles of the gas injection and the improvements reached with the increased pressure. Furthermore the gas injection increased the accuracy measurement of the so-called ghost charges and also intensities per bunch. Those uncertainties are becoming the dominating factor because the uncertainty on the total beam current have been reduced.

Barschel, C

2013-01-01

77

On the variation of galaxy correlations with luminosity  

International Nuclear Information System (INIS)

A method if presented for investigating, in a direct way, the possible variation of galaxy clustering with luminosity, namely the counts of excess galaxies projected near galaxies of known distance. Large variations in either slope or amplitude of the galaxy correlation function are ruled out by the present data. In particular no evidence is found that bright galaxies have a steeper correlation function slope than faint galaxies (the expectation from many 'biased' galaxy formation theories) although the statistical uncertainty for our available sample is too large to allow a definite rejection of this possibility. The data are also consistent with there being no difference in the amplitude of the clustering of bright and faint galaxies, although in this case current uncertainty in the luminosity function would allow up to a factor ? 2 variation. (author).

1987-01-01

78

SLC-2000: A luminosity upgrade for the SLC  

Energy Technology Data Exchange (ETDEWEB)

The authors discuss a possible upgrade to the Stanford Linear Collider (SLC), whose objective is to increase the SLC luminosity by at least a factor 7, to an average Z production rate of more than 35,000 per week. The centerpiece of the upgrade is the installation of a new superconducting final doublet with a field gradient of 240 T/m, which will be placed at a distance of only 70 cm from the interaction point. In addition, several bending magnet in each final focus will be lengthened and two octupole correctors are added. A complementary upgrade of damping rings and bunch compressors will allow optimum use of the modified final focus and can deliver, or exceed, the targeted luminosity. The proposed upgrade will place the SLC physics program in a very competitive position, and will also enable it to pursue its pioneering role as the first and only linear collider.

Breidenbach, M.; Decker, F.J.; Helm, R. [and others

1996-08-01

79

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Document Server

After successful LHC operation at 7 TeV in 2011, the LHC is scheduled to deliver even more data in 2012. 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 300 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...

Elsing, M; The ATLAS collaboration

2012-01-01

80

ATLAS Upgrades Towards the High Luminosity LHC  

CERN Multimedia

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

 
 
 
 
81

The K-Band Galaxy Luminosity Function  

CERN Document Server

We measured the K-band luminosity function using a complete sample of 4192 morphologically-typed 2MASS galaxies with 7 -0.5) galaxies have similarly shaped luminosity functions, alpha_e=-0.92+/-0.10 and alpha_l=-0.87+/-0.09. The early-type galaxies are brighter, M_*e=-23.53+/-0.06 mag compared to M_*l=-22.98\\pm0.06 mag, but less numerous, n_*e=(0.0045+/-0.0006)h^3/Mpc^3 compared to n_*l=(0.0101+/-0.0013)h^3/Mpc^3 for H_0=100h km/s Mpc, such that the late-type galaxies slightly dominate the K-band luminosity density, j_late/j_early=1.17+/-0.12. Our morphological classifications are internally consistent, consistent with previous classifications and lead to luminosity functions unaffected by the estimated uncertainties in the classifications. These luminosity functions accurately predict the K-band number counts and redshift distributions for K < 18 mag, beyond which the results depend on galaxy evolution and merger histories.

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

2000-01-01

82

Spatial and luminosity distributions of galactic satellites  

Science.gov (United States)

We investigate the luminosity functions and projected number density profiles of galactic satellites around isolated primaries of different luminosity. We measure these quantities for model satellites placed into the Millennium and Millennium II dark matter simulations by the GALFORM semi-analytic galaxy formation model for different bins of primary galaxy magnitude and we investigate their dependence on satellite luminosity. We compare our model predictions to the data of Guo et al. from the Sloan Digital Sky Survey Data Release 8 (SDSS DR8). First, we use a mock light-cone catalogue to verify that the method we used to count satellites in the SDSS DR8 is unbiased. We find that the radial distributions of model satellites can be fitted by a Navarro-Frenk-White profile similar to those around comparable primary galaxies in the SDSS DR8, with only slight differences at low luminosities and small projected radii. However, when splitting the satellites by colour, the model and SDSS satellite systems no longer resemble one another, with many red model satellites in contrast to the dominant blue fraction at similar luminosity in the SDSS. The few model blue satellites are also significantly less centrally concentrated in the halo of their stacked primary than their SDSS counterparts. We discuss how these discrepancies may reflect inadequacies in the treatment of the processes that determine the star formation histories of small galaxies in the model.

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

2013-09-01

83

The luminosity function of field galaxies  

CERN Multimedia

Schmidt's method for construction of luminosity function of galaxies is generalized by taking into account the dependence of density of galaxies from the distance in the near Universe. The logarithmical luminosity function (LLF) of field galaxies depending on morphological type is constructed. We show that the LLF for all galaxies, and also separately for elliptical and lenticular galaxies can be presented by Schechter function in narrow area of absolute magnitudes. The LLF of spiral galaxies was presented by Schechter function for enough wide area of absolute magnitudes: . Spiral galaxies differ slightly by parameter . At transition from early spirals to the late spirals parameter in Schechter function is reduced. The reduction of mean luminosity of galaxies is observed at transition from elliptical galaxies to lenticular galaxies, to early spiral galaxies, and further, to late spiral galaxies, in a bright end, . The completeness and the average density of samples of galaxies of different morphological types...

Mahtessian, A P

2011-01-01

84

Using Spectral Flux Ratios to Standardize SN Ia Luminosities  

CERN Multimedia

We present a new method to standardize Type Ia supernova (SN Ia) luminosities to ~<0.13 magnitudes using flux ratios from a single flux-calibrated spectrum per SN. Using Nearby Supernova Factory spectrophotomery of 58 SNe Ia, we performed an unbiased search for flux ratios which correlate with SN Ia luminosity. After developing the method and selecting the best ratios from a training sample, we verified the results on a separate validation sample and with data from the literature. We identified multiple flux ratios whose correlations with luminosity are stronger than those of light curve shape and color, previously identified spectral feature ratios, or equivalent width measurements. In particular, the flux ratio R(642/443) = F(642 nm) / F(443 nm) has a correlation of 0.95 with SN Ia absolute magnitudes. Using this single ratio as a correction factor produces a Hubble diagram with a residual scatter standard deviation of 0.125 +- 0.011 mag, compared with 0.161 +- 0.015 mag when fit with the SALT2 light cur...

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

2009-01-01

85

THE GALAXY LUMINOSITY FUNCTION DURING THE REIONIZATION EPOCH  

International Nuclear Information System (INIS)

[en] The new Wide Field Camera 3/IR observations on the Hubble Ultra-Deep Field (HUDF) started investigating the properties of galaxies during the reionization epoch. To interpret these observations, we present a novel approach inspired by the conditional luminosity function method. We calibrate our model to observations at z = 6 and assume a non-evolving galaxy luminosity versus halo mass relation. We first compare model predictions against the luminosity function (LF) measured at z = 5 and z = 4. We then predict the LF at z ? 7 under the sole assumption of evolution in the underlying dark-matter halo mass function. Our model is consistent with the observed z ?> 7 galaxy number counts in the HUDF survey and suggests a possible steepening of the faint-end slope of the LF: ?(z ?> 8) ?* ?> 10-4) might provide ?>75% of the total reionizing flux. Assuming escape fraction f esc ? 0.2, clumping factor C ? 5, top-heavy initial mass function (IMF), and low metallicity, galaxies below the detection limit produce complete reionization at z ?> 8. For solar metallicity and normal stellar IMF, reionization finishes at z ?> 6, but a smaller C/f esc is required for an optical depth consistent with the Wilkinson Microwave Anisotropy Probe measurement. Our model highlights that the star formation rate in sub-L * galaxies has a quasi-linear relation to dark-matter halo mass, suggesting that radiative and mechanical feedback were less effective at z ? 6 than today.

2010-05-10

86

EU supports the LHC high-luminosity study  

CERN Document Server

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

87

Luminosity function of high redshift quasars  

Energy Technology Data Exchange (ETDEWEB)

Data from ten different emission-line surveys are included in a study of the luminosity function of high redshift quasars. Five of the surveys are analyzed through microdensitometric techniques and the data for new quasars are given. The uncertainties in magnitudes, redshifts, and line equivalent widths are assessed and found to be +-0.3 mag. +-0.04 in z and approx. 30%, respectively. Criteria for selecting the redshift range 1.8 less than or equal to z < 2.5 are discussed and the apparent magnitude distribution for quasars in that range is compared to that of UVX-selected quasars. A separate sample of blue continuum objects is defined by examining the spectral continuum for confirmed quasars. The surface density of the blue objects compared to that of high redshift quasars in the same survey indicates the high redshift quasars comprise about 20% of the blue continuum objects. The completion limits of the new surveys are examined in detail to establish the best sample for the study of the luminosity function. The luminosity function of high redshift quasars is determined assuming cosmological redshifts, ..lambda.. = 0, and H/sub o/ = 75 km s/sup -1/ Mpc/sup -1/ for each of two cosmologies (q/sub 0/ = 1 and q/sub 0/ = 0). For either cosmology, the function exhibits a steep increase with magnitude at high luminosities and a gentler increase at intermediate luminosities. Data from the new surveys indicate a possible turnover at the faint end of the distribution. Total volume densities of quasars are computed for each of three extrapolations of the trend of the data to low luminosities. These densities are compared to those of active galaxies and field galaxies.

Vaucher, B.G.

1982-01-01

88

The luminosity of galactic components and morphological segregation  

International Nuclear Information System (INIS)

The luminosities of the bulge and disk components of disk galaxies are analyzed, and the possible correlation of these luminosities with morphological type and local density is explored. Galaxies of different types are found to be located in distinct bands in the bulge-to-disk luminosity ratio vs total luminosity diagram, allowing the determination of the typical bulge luminosity function of disk galaxies of different types from their respective total luminosity functions, along with a better characterization of morphological segregation among disk galaxies. No evidence for any bulge luminosity segregation is found, and disks appear to be less luminous with increasing local density. 33 refs

1989-01-01

89

Calculating luminosity for a coupled Tevatron lattice  

International Nuclear Information System (INIS)

The traditional formula for calculating luminosity assumes an uncoupled lattice and makes use of one-degree-of-freedom lattice functions, ?H and ?v, for relating transverse beam widths to emittances. Strong coupling requires changing this approach. It is simplest to employ directly the linear normal form coordinates of the one turn map. An equilibrium distribution in phase space is expressed as a function of the Jacobian's eigenvectors and beam size parameters or emittances. Using the equilibrium distributions an expression for the luminosity was derived and applied to the Tevatron lattice, which was coupled due to a quadrupole roll

1995-01-01

90

Analytical estimation of the effects of crossing angle on the luminosity of an e sup + e sup - circular collider  

CERN Multimedia

Based on the theory established in Nucl. Instr. and Meth. A 463 (2001) 50, in this note we investigate the effects of the crossing angle on the luminosity of an e sup + e sup - circular collider. Analytical expression for the luminosity reduction factor is established and compared with simulation result.

Gao, J

2002-01-01

91

Luminosity enhancement in relativistic jets and altered luminosity functions for beamed objects  

Energy Technology Data Exchange (ETDEWEB)

Due to relativistic effects, the observed emission from relativistic jets is quite different from the rest frame emission. We discuss systematic differences between the observed and intrinsic intensities of sources in which jet phenomena are occurring. Assuming that jets have a power-law luminosity function of slope ..beta.., we calculate the observed luminosity distribution as a function of the velocity of the jet, the spectral index of the rest frame emission, and the range of angles of the jets relative to our line of sight. The result is well approximated by two power laws, the higher luminosity end having the original power law index ..beta.. and the lower luminosity end having a flattened exponent independent of ..beta.. and only slightly greater than 1. We then investigate a model consisting of beamed emission from a jet and unbeamed emission from a stationary central component. The luminosity functions for these two-component sources are calculated for two ranges of angles. For sources in which beaming is important, the luminosity function is much flatter. Because of this, the relative numbers of ''beamed'' and ''unbeamed'' sources detected on the sky depend strongly on the luminosity at which the comparison is made.

Urry, C.M.; Shafer, R.A.

1984-05-15

92

Prospects for indirect luminosity measurements at LHCb  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We summarise the prospects for indirect luminosity measurements at LHCb. Two candidate processes have been identified for such measurements: electroweak boson production and elastic dimuon production via two photon fusion. The cross-section for W and Z production at LHCb has been calculated at NNLO ...

Anderson, J

93

Recent improvements in luminosity at PEP  

International Nuclear Information System (INIS)

[en] 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

1983-01-01

94

Phase Space Constraints on Neutrino Luminosities  

CERN Multimedia

While the importance of phase space constraints for gravitational clustering of neutrinos (which are fermions) is well recognized, the explicit use of such constraints to limit neutrino emission from ultra energetic sources has not been stressed. Special and general relativistic phase space constraints are shown to limit neutrino luminosities in compact sources in various situations.

Sivaram, C; Samartha, C A

2007-01-01

95

How covariant is the galaxy luminosity function?  

CERN Document Server

We investigate the error properties of certain galaxy luminosity function (GLF) estimators. Using a cluster expansion of the density field, we show how, for both volume and flux limited samples, the GLF estimates are covariant. The covariance matrix can be decomposed into three pieces: a diagonal term arising from Poisson noise; a sample variance term arising from large-scale structure in the survey volume; an occupancy covariance term arising due to galaxies of different luminosities inhabiting the same cluster. To evaluate the theory one needs: the mass function and bias of clusters, and the conditional luminosity function (CLF). We use a semi-analytic model (SAM) galaxy catalogue from the Millennium run N-body simulation and the CLF of Yang et al. (2003) to explore these effects. The GLF estimates from the SAM and the CLF qualitatively reproduce results from the 2dFGRS. We also measure the luminosity dependence of clustering in the SAM and find reasonable agreement with 2dFGRS results for bright galaxies. ...

Smith, Robert E

2012-01-01

96

Recent improvements in luminosity at PEP  

Energy Technology Data Exchange (ETDEWEB)

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.

Helm, R.; Allen, M.; Chao, A.

1983-03-01

97

Spatial and luminosity distributions of galactic satellites  

CERN Document Server

We investigate the luminosity functions (LFs) and projected number density profiles of galactic satellites around isolated primaries of different luminosities. We measure these quantities for model satellites placed into the Millennium and Millennium II dark matter simulations by the GALFORM semi-analytic galaxy formation model for different bins of primary galaxy magnitude and we investigate their dependence on satellite luminosity. We compare our model predictions to the data of Guo et al. from the Sloan Digital Sky Survey Data Release 8 (SDSS DR8). First, we use a mock light-cone catalogue to verify that the method we used to count satellites in the SDSS DR8 is unbiased. We find that the radial distributions of model satellites are similar to those around comparable primary galaxies in the SDSS DR8, with only slight differences at low luminosities and small projected radii. However, when splitting the satellites by colour, the model and SDSS satellite systems no longer resemble one another, with many red m...

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

2013-01-01

98

Description of nuclear interaction in Keldysh diagram technique and neutrino luminosity of neutron stars  

International Nuclear Information System (INIS)

Keldysh's diagram technique is formulated for description of equilibrium and nonequilibrium nuclear systems. Nuclear interaction is built within the theory of finite Fermi systems. The formalism is applied to calculating probabilities of various processes. Possibilities of the approach are shown in the calculation of the luminosity of the main reactions which contribute to cooling of neutron stars. The luminosity is calculated produced by the process nn ? npe?-bar which proceeds essentially differently in dense and dilute nucleon medium. The dependence of the luminosity upon the nucleon-nucleon correlation factor is analyzed. The formalism is applied to systems with pairing. Contributions is calculated introduced to the luminosity by reactions npaired ? n??-bar and ppaired ? p??-bar which proceed only in the presence of nucleon pairing. Consequences of the results are discussed in the scenario of cooling of the neutron stars

1987-01-01

99

How covariant is the galaxy luminosity function?  

Science.gov (United States)

We investigate the error properties of certain galaxy luminosity function (GLF) estimators. Using a cluster expansion of the density field, we show how, for both volume- and flux-limited samples, the GLF estimates are covariant. The covariance matrix can be decomposed into three pieces: a diagonal term arising from Poisson noise, a sample variance term arising from large-scale structure in the survey volume and an occupancy covariance term arising due to galaxies of different luminosities inhabiting the same cluster. To evaluate the theory one needs the mass function and bias of clusters, and the conditional luminosity function (CLF). We use a semi-analytic model (SAM) galaxy catalogue from the Millennium Run N-body simulation and the CLF of Yang et al. to explore these effects. The GLF estimates from the SAM and the CLF qualitatively reproduce results from the two degree Field Galaxy Redshift Survey (2dFGRS). We also measure the luminosity dependence of clustering in the SAM and find reasonable agreement with 2dFGRS results for bright galaxies. However, for fainter galaxies, L 0.5. Our theory is in good agreement with these measurements. These strong correlations can be attributed to sample variance. For a flux-limited survey of similar volume, the estimates are only slightly less correlated. We explore the importance of these effects for GLF model parameter estimation. We show that neglecting to take into account the bin-to-bin covariances, induced by the large-scale structures in the survey, can lead to significant systematic errors in best-fitting parameters. For Schechter function fits, the most strongly affected parameter is the characteristic luminosity L*, which can be significantly underestimated.

Smith, Robert E.

2012-10-01

100

Identifying the Low Luminosity Population of Embedded Protostars in the c2d Observations of Clouds and Cores  

CERN Multimedia

We present a search for all embedded protostars with internal luminosities 4E-3 (d/140 pc)^2 solar luminosities, a factor of 25 better than the sensitivity of IRAS to such objects. We present selection criteria used to identify candidates from the Spitzer data and examine complementary data to decide whether each candidate is truly an embedded protostar. We find a tight correlation between the 70 micron flux and internal luminosity of a protostar, an empirical result based on observations and two-dimensional radiative transfer models of protostars. We identify 50 embedded protostars with Lint < 1 solar luminosities; 15 have Lint < 0.1 solar luminosities. The intrinsic distribution of source luminosities increases to lower luminosities. While we find sources down to the above sensitivity limit, indicating that the distribution may extend to luminosities lower than probed by these observations, we are able to rule out a continued rise in the distribution below 0.1 solar luminosities. Between 75-85% of co...

Dunham, Michael M; Evans, Neal J; Bourke, Tyler L; Huard, Tracy L; Myers, Philip C; Kauffmann, Jens

2008-01-01

 
 
 
 
101

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.).

1984-01-01

102

Wet drift chambers for precise luminosity  

Energy Technology Data Exchange (ETDEWEB)

A set of high-precision compact drift chambers has been a vital component of the OPAL luminosity monitor since the start of data-taking at LEP. They were augmented in 1992 by the addition of Small Angle Reference Chambers with a very similar design to the original chamber. The performance of the chambers is reviewed, highlighting both the importance of using polyalkylene glycol (Breox) to maintain a uniform and parallel electric field and the construction techniques used to sustain the required field strength. We describe some of the operating problems, with their solutions, and show how the chambers have been used in achieving a systematic error of 0.41% on the luminosity measurement. ((orig.))

Anderson, B.E. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Kennedy, B.W. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Ahmet, K. (Department of Physics, Birkbeck College, Malet Street, London WC1E 7VV (United Kingdom)); Attree, D.J. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Barraclough, G.A. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Cresswell, M.J. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Hayes, D.A. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)); Miller, D.J. (Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kin

1994-09-01

103

Luminosity of continuous beams with crossing angle  

Energy Technology Data Exchange (ETDEWEB)

Since it appears difficult to reach a luminosity of even 10/sup 32/ cm/sup -2/ sec/sup -1/ with (p, anti p) 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 in the first ICFA report by Keil and King, based on an optimization procedure developed earlier by Keil. In this note, 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.

Smith, L.

1982-10-01

104

Solar gravitational energy and luminosity variations  

CERN Multimedia

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

105

The Luminosity Function of Elliptical Galaxies  

Science.gov (United States)

We present 292 new redshifts of elliptical galaxies selected from the APM Bright Galaxy Survey. We use these data together with published redshifts and bJ apparent magnitudes from the APM Bright Galaxy Survey in order to estimate the shape of the Luminosity Function of a total sample of 535 ellipticals. We use the Maximum Likelihood method for the determination of the best fitting parameters ? and M* of a Schechter Function. In order to provide tests for systematics and suitable error estimates we apply Monte Carlo techniques which are also used to deal with incompleteness effects in the data. In agreement with other authors our results indicate a relative lack of low luminosity ellipticals compared to other morphological types. The best fitting shape parameters derived are ?=0.20±0.2S and MBJ*=-20.0±0.3. We do not find evidence for a dependence of these parameters on environment

Muriel, Hernan; Nicotra, Mariono A.; Lambas, Diego G.

1995-09-01

106

Evolution of QSO and QSG luminosities  

International Nuclear Information System (INIS)

The dependences of the magnitude m0 of the statistically brightest QSOs and QSGs on their lg z (z is a red shift) are constructed. The slope of the diagram for QSOs is 2.2. The GSGs' magnitude drops quickly to approximately 17sup(m) at z approximately equal to 0.3 and remains nearly onstant at larger z. The differences in m0 (lg z) for QSOs and QSGs reach approximately 1.sup(m)5 at z approximately equal to 0.3, and, as is shown, cannot be accounted for by the detection selection. The dependence m0 (lg z) is explained by the decrease at z > 0.3 of the QSOs' luminosities by 0sup(m).46 and of the QSCs' luminosities by 0sup(m).70 at a time jnterval of 109 years

1983-01-01

107

Evolution of QSG and QSG luminosities  

International Nuclear Information System (INIS)

The dependences of the magnitude m0 of the statistically brightest QSOs and QSGs on their lg z (z is a red shift) are constructed. The slope of the diagram for QSOs is 2.2. The GSGs' magnitude drops quickly to approximately 17sup(m) at z approximately equal to 0.3 and remains nearly onstant at larger z. The differences in m0 (lg z) for QSOs and QSGs reach approximately 1.sup(m)5 at z approximately equal to 0.3, and, as is shown, cannot be accounted for by the detection selection. The dependence m0 (lg z) is explained by the decrease at z > 0.3 of the QSOs' luminosities by 0sup(m).46 and of the QSCs luminosities by 0sup(m).70 at a time jnterval of 109 years

1983-01-01

108

IMPROVED PHOTOMETRIC REDSHIFTS WITH SURFACE LUMINOSITY PRIORS  

International Nuclear Information System (INIS)

[en] We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at 0.1 ?0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the fractional redshift error does not change much.

2009-01-01

109

Luminosity Measurement at the International Linear Collider  

CERN Multimedia

The International Linear Collider (ILC) is a proposed electron-positron collider with a center-of-mass energy of 500~GeV, and a peak luminosity of $2 \\cdot 10^{34}~\\mathrm{cm}^{-2}\\mathrm{s}^{-1}$. The ILC will complement the Large Hadron Collider, a proton-proton accelerator, and provide precision measurements, which may help in solving some of the fundamental questions at the frontier of scientific research, such as the origin of mass and the possible existence of new principles of nature. The linear collider community has set a goal to achieve a precision of $10^{-4}$ on the luminosity measurement at the ILC. This may be accomplished by constructing a finely granulated calorimeter, which will measure Bhabha scattering at small angles. The Bhabha cross-section is theoretically known to great precision, yet the rate of Bhabha scattering events, which would be measured by the luminosity detector, will be influenced by beam-beam effects, and by the inherent energy spread of the collider. The electroweak radiat...

Sadeh, Iftach

2010-01-01

110

High-luminosity solid-state lasers  

Energy Technology Data Exchange (ETDEWEB)

Means for the elimination of processes restricting the luminosity of solid-state lasers and the construction of solid-state lasers with high output luminosity are reviewed. Mechanisms leading to reductions in radiation intensity and enhancements in radiation divergence by such causes as loss of material radiation stability, linear phase distortion, diffraction and self-focussing are examined. The suppression of self-focusing by means of spatial filtering, optical retranslators and the use of circular polarization is considered, and operational experience with a Nd-glass laser making use of the latter two techniques is reported. Advantages of high-gain amplifiers and guided wave propagation are also noted, and the optimization of the solid-state laser system is discussed. Finally, attention is given to increasing laser luminosity by techniques of nonlinear optics, including wave front reflection, beam averaging and induced scattering for pulse compression. It is concluded that by the use of these techniques, the theoretical limiting brightness of 10 to the 19th to 10 to the 20th W/sq cm may be obtained.

Mak, A.A.; Liubimov, V.V.; Serebriakov, V.A.; Fromzel, V.A.; Iashin, V.E.

1982-10-01

111

The Luminosity Profiles of Brightest Cluster Galaxies  

CERN Multimedia

(Abridged) We have derived detailed R band luminosity profiles and structural parameters for a total of 430 brightest cluster galaxies (BCGs), down to a limiting surface brightness of 24.5 mag/arcsec^2. Light profiles were initially fitted with a Sersic's R^(1/n) model, but we found that 205 (~48) BCGs require a double component model to accurately match their light profiles. The best fit for these 205 galaxies is an inner Sersic model, with indices n~1-7, plus an outer exponential component. Thus, we establish the existence of two categories of the BCGs luminosity profiles: single and double component profiles. We found that double profile BCGs are brighter ~0.2 mag than single profile BCG. In fact, the Kolmogorov-Smirnov test applied to these subsamples indicates that they have different total magnitude distributions, with mean values M_R=-23.8 +/- 0.6 mag for single profile BCGs and M_R=-24.0 +/- 0.5 mag for double profile BCGs. We find that partial luminosities for both subsamples are indistinguishable up...

Donzelli, C J; Madrid, Juan P

2011-01-01

112

Mini-? insertion and luminosity for the RHIC lattice  

International Nuclear Information System (INIS)

Requirement and implication of the mini-? insertion, where a pair of common quadrupoles are inserted between the interaction point and the frist beam crossing dipole, in RHIC lattice is studied. For the heavy ion operation, we find that ? = 1m can be achieved with a +-5m free space for experimental setup and /cflx /beta// = 500m. The beam size limitation is located at the second beam crossing dipole BC2, where 8cm coil i.d. is considered. When the machine is operating at the proton-heavy ion collision mode, these common quadrupoles should be removed physically in order to let both beams crossing the center line at 3.4 mrad. These mini-? insertion can increase the luminosity by a factor of 2 /approximately/ 3. For the proton-proton collision mode, we find that ? = 0.5m is also operable without the mini-? quadrupoles due to smaller emittance for the proton beam. The corresponding /cflx /beta// is 2400m. When the mini-? quads are used, ? = 0.25m can be achieved. The ultimate luminosity for the proton-proton collision is of the order of 1033/cm2 sec, which may be useful in the quest of the B physics studies. 3 refs., 3 figs., 3 tabs

1989-01-01

113

The Luminosity Dependence of the Galaxy Merger Rate  

CERN Document Server

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

Patton, D R

2008-01-01

114

CORRELATION BETWEEN GROUP LOCAL DENSITY AND GROUP LUMINOSITY  

Energy Technology Data Exchange (ETDEWEB)

In this study, we investigate the correlation between group local number density and total luminosity of groups. In four volume-limited group catalogs, we can conclude that groups with high luminosity exist preferentially in high-density regions, while groups with low luminosity are located preferentially in low-density regions, and that in a volume-limited group sample with absolute magnitude limit M{sub r} = -18, the correlation between group local number density and total luminosity of groups is the weakest. These results basically are consistent with the environmental dependence of galaxy luminosity.

Deng Xinfa [School of Science, Nanchang University, Jiangxi 330031 (China); Yu Guisheng [Department of Natural Science, Nanchang Teachers College, Jiangxi 330103 (China)

2012-11-10

115

Galaxy luminosity function: a new analytic expression  

Scientific Electronic Library Online (English)

Full Text Available 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 observational 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.

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

2004-06-01

116

Observed variability of the solar luminosity  

International Nuclear Information System (INIS)

Data on solar luminosity variations are compiled in graphs and analyzed, with a focus on the SMM satellite bolometric measurements and other observations made since 1983. Consideration is given to total irradiance measurements in integrated light; emission-line variability in the visible, UV, and IR; mechanisms contributing to the solar variability (sunspots, faculae, rotation, oscillations, granulation, and active networks); the role of the solar magnetic cycle; and other observable parameters indicating variability. Also discussed are the effects of solar variations on the earth climate and the implications of the observations for theoretical models of convective-envelope processes (thermal diffusion near the surface and magnetic pressure in the interior). 190 references.

1988-01-01

117

The Luminosity Function of M3  

CERN Document Server

We present a high precision, large sample luminosity function (LF) for the Galactic globular cluster M3. With a combination of ground based and Hubble Space Telescope data we cover the entire radial extent of the cluster. The observed LF is well fit by canonical standard stellar models from the red giant branch (RGB) tip to below the main sequence turnoff point. Specifically, neither the RGB LF-bump nor subgiant branch LF indicate any breakdown in the standard models. On the main sequence we find evidence for a flat initial mass function and for mass segregation due to the dynamical evolution of the cluster.

Rood, R T; Paltrinieri, B; Ferraro, F R; Pecci, F F; Dorman, B; Chieffi, A; Straniero, O; Buonanno, R

1999-01-01

118

Cluster luminosity function and n$^{th  

Science.gov (United States)

We define here a standard candle to determine the distance of clusters of galaxies and to investigate their peculiar velocities by using the n(th) rank galaxy (magnitude m_n). We address the question of the universality of the luminosity function for a sample of 28 rich clusters of galaxies (cz =~ 20000 km.s(-1) ) in order to model the influence on m_n of cluster richness. This luminosity function is found to be universal and the fit of a Schechter profile gives alpha =-1.50+/-0.11 and Mbj*=-19.91 +/-0.21 in the range [-21,-17]. The uncorrected distance indicator m_n is more efficient for the first ranks n. With n=5, we have a dispersion of 0.61 magnitude for the (m_n,5log(cz)) relation. When we correct for the richness effect and subtract the background galaxies we reduce the uncertainty to 0.21 magnitude with n=15. Simulations show that a large part of this dispersion originates from the intrinsic scatter of the standard candle itself. These provide upper bounds on the amplitude sigma_v of cluster radial peculiar motions. At a confidence level of 90 %, the dispersion is 0.13 magnitude and sigma_v is limited to 1200 km.s(-1) for our sample of clusters.

Rauzy, S.; Adami, C.; Mazure, A.

1998-09-01

119

in CMS. The low luminosity case.  

UK PubMed Central (United Kingdom)

We evaluate the maximal reach of the CMS detector for discovery of squarks and gluinos at largetan # = 35 in EmissT + leptons + jets final states during the initial low luminosity phase of LHC. Foran integrated luminosity of 10 fb -1 a signal should be observed if squarks and gluinos have massesnot exceeding#1.3 TeV.1)On leave from ITEP, Moscow, Russia1 IntroductionRecent results on the b#s# decays by the CLEO [1] and ALEPH [2] experiments renewed interest in thelarge tan # domain of supersymmetric theories. Those measurements place additional strong constraints on theparameter space of mSUGRA models, especially for large tan # and < 0 [3]. Large tan # values cause changesin sparticle phenomenology by enhancing b and # couplings and mixings [4].On the technical side, the recent adaptations of the event generator ISAJET [5] made it possible to perform reliablesimulations for tan # > 10.In this work we complete the previous studies [6] by taking large tan # ...

S. Abdullin; Z. Antunovic; F. Charles; M. Dzelalija

120

Jet Cleansing: Pileup Removal at High Luminosity  

CERN Multimedia

One of the greatest impediments to extracting useful information from high luminosity hadron-collider data is radiation from secondary collisions (i.e. pileup) which can overlap with that of the primary interaction. In this paper we introduce a simple jet-substructure technique termed cleansing which can consistently correct for large amounts of pileup in an observable independent way. Cleansing works at the subjet level, combining tracker and calorimeter-based data to reconstruct the pileup-free primary interaction. The technique can be used on its own, with various degrees of sophistication, or in concert with jet grooming. We apply cleansing to both kinematic and jet shape reconstruction, finding in all cases a marked improvement over previous methods both in the correlation of the cleansed data with uncontaminated results and in measures like S/rt(B). Cleansing should improve the sensitivity of new-physics searches at high luminosity and could also aid in the comparison of precision QCD calculations to co...

Krohn, David; Schwartz, Matthew D; Wang, Lian-Tao

2013-01-01

 
 
 
 
121

Discovery of distant high luminosity infrared galaxies  

CERN Document Server

We have developed a method for selecting the most luminous galaxies detected by IRAS based on their extreme values of R, the ratio of 60 micron and B-band luminosity. These objects have optical counterparts that are close to or below the limits of Schmidt surveys. We have tested our method on a 1079 deg^2 region of sky, where we have selected a sample of IRAS sources with 60 micron flux densities greater than 0.2 Jy, corresponding to a redshift limit z~1 for objects with far-IR luminosities of 10^{13} L_sun. Optical identifications for these were obtained from the UK Schmidt Telescope plates, using the likelihood ratio method. Optical spectroscopy has been carried out to reliably identify and measure the redshifts of six objects with very faint optical counterparts, which are the only objects with R>100 in the sample. One object is a hyperluminous infrared galaxy (HyLIG) at z=0.834. Of the remaining, fainter objects, five are ultraluminous infrared galaxies (ULIGs) with a mean redshift of 0.45, higher than th...

Van der Werf, P P; Shaver, P A; Hawkins, M R S; Werf, Paul P. van der

1999-01-01

122

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

123

Selected issues for the LHC luminosity upgrade  

International Nuclear Information System (INIS)

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

2008-01-01

124

The luminosity density of red galaxies  

CERN Multimedia

A complete sample of $7.7\\times 10^4$ galaxies with five-band imaging and spectroscopic redshifts from the Sloan Digital Sky Survey is used to determine the fraction of the optical luminosity density of the Local Universe (redshifts $0.02luminosity density at $0.7 \\mathrm{\\mu m...

Hogg, D W; Strateva, I; Hogg, David W.; Blanton, Michael; Strateva, Iskra

2002-01-01

125

The Evolving Luminosity Function of Red Galaxies  

CERN Multimedia

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

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

2006-01-01

126

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

127

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.).

1983-02-10

128

Luminosity and disruption in e-e- linear colliders  

Energy Technology Data Exchange (ETDEWEB)

We present an empirical analytic approximation for the luminosity ''de-enhancement'' factor H{sub D} in e{sup -}e{sup -} collisions, as a function of the disruption parameters D{sub x}, D{sub y}, the hour-glass parameters A{sub x}, A{sub y}, and the beam aspect ratio R identical to sigma{sub x}/sigma{sub y}. We treat Gaussian beams with essentially arbitrary aspect ratio, assuming only that the vertical beam size is less than or equal to the horizontal beam size and that the vertical beta function is less than or equal to the horizontal beta function.

Thompson, Kathleen A

1999-10-11

129

60 micron luminosity evolution of rich clusters of galaxies  

Energy Technology Data Exchange (ETDEWEB)

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.

Kelly, D.M.; Rieke, G.H. (Steward Observatory, Tucson, AZ (USA))

1990-10-01

130

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.

1990-01-01

131

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

132

A Modeling of the Super-Eddington Luminosity in Nova Outbursts: V1974 Cygni  

CERN Document Server

We have modeled nova light curves exceeding the Eddington luminosity. It has been suggested that a porous structure develops in nova envelopes during the super Eddington phase and the effective opacity is much reduced for such a porous atmosphere. Based on this reduced opacity model, we have calculated envelope structures and light curves of novae. The optically thick wind model is used to simulate nova winds. We find that the photospheric luminosity and the wind mass-loss rate increase inversely proportional to the reducing factor of opacities, but the wind velocity hardly changes. We also reproduce the optical light curve of V1974 Cygni (Nova Cygni 1992) in the super-Eddington phase, which lasts 13 days from the optical peak 1.7 mag above the Eddington luminosity.

Kato, M; Kato, Mariko; Hachisu, Izumi

2005-01-01

133

The 2dF Galaxy Redshift Survey: luminosity dependence of galaxy clustering  

Science.gov (United States)

We investigate the dependence of the strength of galaxy clustering on intrinsic luminosity using the Anglo-Australian two degree field galaxy redshift survey (2dFGRS). The 2dFGRS is over an order of magnitude larger than previous redshift surveys used to address this issue. We measure the projected two-point correlation function of galaxies in a series of volume-limited samples. The projected correlation function is free from any distortion of the clustering pattern induced by peculiar motions and is well described by a power law in pair separation over the range 0.1MbJ-5log10h=-19.7) galaxies in real space is well-fitted by a correlation length r0=4.9+/-0.3h-1Mpc and power-law slope ?=1.71+/-0.06. The clustering amplitude increases slowly with absolute magnitude for galaxies fainter than M*, but rises more strongly at higher luminosities. At low luminosities, our results agree with measurements from the Southern Sky Redshift Survey 2 by Benoist et al. However, we find a weaker dependence of clustering strength on luminosity at the highest luminosities. The correlation function amplitude increases by a factor of 4.0 between MbJ-5log10h=-18 and -22.5, and the most luminous galaxies are 3.0 times more strongly clustered than L* galaxies. The power-law slope of the correlation function shows remarkably little variation for samples spanning a factor of 20 in luminosity. Our measurements are in very good agreement with the predictions of the hierarchical galaxy formation models of Benson et al.

Norberg, Peder; Baugh, Carlton M.; Hawkins, Ed; Maddox, Steve; Peacock, John A.; Cole, Shaun; Frenk, Carlos S.; Bland-Hawthorn, Joss; Bridges, Terry; Cannon, Russell; Colless, Matthew; Collins, Chris; Couch, Warrick; Dalton, Gavin; De Propris, Roberto; Driver, Simon P.; Efstathiou, George; Ellis, Richard S.; Glazebrook, Karl; Jackson, Carole; Lahav, Ofer; Lewis, Ian; Lumsden, Stuart; Madgwick, Darren; Peterson, Bruce A.; Sutherland, Will; Taylor, Keith

2001-11-01

134

The Cepheid infrared period-luminosity relations  

International Nuclear Information System (INIS)

The angular diameters of Cepheid variable stars derived by Hindsley and Bell (1989) are combined with model atmosphere calculations of infrared visual surface brightnesses to derive infrared light curves. While the shape of the light curves matches the observations very well, the calculated apparent magnitudes are about 0.1 mag too faint. Reasons for this discrepancy are given. The models predict that the brightest J magnitude occurs at about phase 0.1, while the brightest H and K occur at about phase 0.3, in agreement with observation. The Cepheid distances derived by Hindsley and Bell are used to obtain infrared period-luminosity relations, for the J, H, and K bands. These are compared with the results found by other authors. Mean colors are found as a function of phase and are used to convert the period, mean absolute visual magnitude relation to period, mean absolute infrared magnitude relations. 19 refs.

1990-01-01

135

M Subdwarfs The Population II Luminosity Function  

CERN Multimedia

We present results of a study of very low mass halo stars. Using a sample of proper motion stars identified from plate material taken as part of the first and second Palomar Sky Surveys, we measure the space density, metallicity distribution, and kinematics of the Population II M subdwarfs. Our overall luminosity function is in good agreement with previous analyses of the space density of nearby very-low-mass halo subdwarfs, and confirms the discrepancy between local analyses and the space densities inferred from deep HST starcounts. We show for the first time that both the metallicity distribution and kinematics of late-type halo subdwarfs are consistent with those of their higher mass metal-poor counterparts. Dividing our sample by abundance, we find no evidence that the mass function of field halo stars is dependent upon metallicity. We provide data for three nearby subdwarfs that may merit additional observations.

Gizis, J E

1999-01-01

136

The luminosity function in NGC 2023  

International Nuclear Information System (INIS)

Sellgren (1983) has shown that the young stellar cluster within the molecular cloud associated with the reflection nebula NGC 2023 has a luminosity function consistent with the Salpeter IMF for stars brighter than K = 12 mag. Extrapolation predicts that approximately 50 additional stars brighter than K = 15 mag, arguably of spectral types G through K, should be present. However, images of the cluster using a sensitive two-dimensional IR array reveal no additional cluster members, which suggests that either no low-mass stars have formed or that they are still heavily shrouded in molecular 'cocoons' left over from the star formation process. A straightforward experimental resolution of the alternatives is proposed. 22 refs

1990-01-01

137

The luminosity function in NGC 2023  

Energy Technology Data Exchange (ETDEWEB)

Sellgren (1983) has shown that the young stellar cluster within the molecular cloud associated with the reflection nebula NGC 2023 has a luminosity function consistent with the Salpeter IMF for stars brighter than K = 12 mag. Extrapolation predicts that approximately 50 additional stars brighter than K = 15 mag, arguably of spectral types G through K, should be present. However, images of the cluster using a sensitive two-dimensional IR array reveal no additional cluster members, which suggests that either no low-mass stars have formed or that they are still heavily shrouded in molecular 'cocoons' left over from the star formation process. A straightforward experimental resolution of the alternatives is proposed. 22 refs.

Depoy, D.L.; Lada, E.A.; Gatley, I.; Probst, R. (Observatorio Interamericano de Cerro Tololo, La Serena (Chile) Texas Univ., Austin (USA) Kitt Peak National Observatory, Tucson, AZ (USA))

1990-06-01

138

The Morphological Type Dependence of K-band Luminosity Functions  

CERN Multimedia

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

139

Burst Statistics Using the Lag-Luminosity Relationship  

CERN Document Server

Using the lag-luminosity relation and various BATSE catalogs we create a large catalog of burst redshifts, peak luminosities and emitted energies. These catalogs permit us to evaluate the lag-luminosity relation, and to study the burst energy distribution. We find that this distribution can be described as a power law with an index of alpha=1.76 +/- 0.05 (95% confidence), close to the alpha=2 predicted by the original quasi-universal jet model.

Band, D L; Norris, J P

2003-01-01

140

A luminosity monitor for the Large Hadron Collider  

International Nuclear Information System (INIS)

[en] The Large Hadron Collider (LHC) nominal luminosity is 1034 cm-2 s-1, but special runs at 1028 cm-2 s-1 are also foreseen. In order to cover a luminosity dynamic range of six orders of magnitude, we have studied a new concept of luminosity monitor based on a double mode detector, working as a secondary emission counter at the highest luminosity and as an ionisation chamber at lower levels. We present the description of the device and the results obtained during tests at the CERN PS and SPS beams

2002-07-21

 
 
 
 
141

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

DEFF Research Database (Denmark)

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

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

2013-01-01

142

Luminosity issues in 2009 100 GeV polarized proton run  

Energy Technology Data Exchange (ETDEWEB)

Several luminosity issues are reviewed. Questions remain, which are stated for further investigation. Some suggestions are made for possible luminosity improvement. There are several factors affecting the luminosity in 2009 100 GeV polarized proton run: (1) The highest bunch intensity at RHIC early store (1.5 hour after accramp in this note) in 2009 is 1.25 x 10{sup 11} protons. In 2008 run, it was 1.42 x 10{sup 11} protons, which gives rise to 30% higher luminosity if other conditions are the same. Yellow ramp efficiency is identified as one of the main problem. Meanwhile, the beam-beam induced loss in about 1 hour into collision accounts actually no less than the ramp. (2) The typical transverse emittance at early store is 13 {pi}{micro}m for bunch intensity of 10{sup 11} protons, but it is 17 {pi}{micro} for 1.25 x 10{sup 11} protons. The increase of the emittance implies a 30% difference in luminosity if other conditions are the same. The emittance growth with electron cloud below instability threshold may be partially responsible. Meanwhile, the Booster scraping may also be relevant. (3) The luminosity lifetime in 2009 run is significantly lower than that in 2005, 2006, and 2008 runs. At the beam-beam parameter of 0.01, the typical average luminosity lifetime in early store is 10 hours in 2009, and it is 15 hours in previous runs. Given 8 hours of store time, this implies more than 20% of the difference in integrated luminosity. The 0.7 m betastar adopted in 2009 might be relevant, but the evidence is not fully convincing. On the other hand, the continuing RF voltage ramp in store may be of concern. (4) In the last month of the run, the polarization at RHIC early store is declined from 60% to 55%, a 30% reduction in p{sup 4} factor. It is noted that the Booster scraping is reduced in order to increase bunch intensity at RHIC, and the source polarization is also declined at the same time. Questions regarding these issues are discussed, and some suggestions are made.

Zhang,S.Y.

2009-08-01

143

The Erratic Luminosity Behavior of SAX J1808.4-3658 during Its 2000 Outburst  

Science.gov (United States)

We report on the highly variable and erratic long-term X-ray luminosity behavior of the only known accretion-driven millisecond X-ray pulsar SAX J1808.4-3658 during its 2000 outburst, as observed with the Rossi X-ray Timing Explorer (RXTE) satellite. The maximum observed luminosity is ~2.5×1035 ergs s-1 (3-25 keV; for a distance of 2.5 kpc), which is approximately a factor of 10 lower than that observed during the 1996 and 1998 outbursts. Due to solar constraints, the source could not be observed for several months with RXTE before 2000 January 21. Therefore, the exact moment of the outburst onset is unknown, and the peak luminosity could have been significantly higher. On some occasions SAX J1808.4-3658 was observed with luminosities of ~1035 ergs s-1, but on other occasions it could not be detected with RXTE, resulting in typical upper limits of a few times 1033 ergs s-1 (3-25 keV). The nondetections of the source during its 2000 outburst obtained with the BeppoSAX satellite demonstrate that its luminosity was at times less than 1032 ergs s-1 (0.5-10 keV). However, only a few days after these BeppoSAX observations, we detected the source again with RXTE at high luminosities, giving a factor of greater than 1000 of luminosity swings in this systems on timescales of days. The last detection of SAX J1808.4-3658 with RXTE was on 2000 May 13, almost 4 months after the first detection during this outburst. Due to the lack of sensitivity and observations during the 1996 and 1998 outbursts, it cannot be excluded that after those outbursts the source remained active for months and that the source behavior during the 2000 outburst is not unique. Long duration activity at low luminosities has been observed in other transients (both neutron stars and black holes), although not with such extreme variability, which might point to a different origin for this behavior for the millisecond X-ray pulsar.

Wijnands, Rudy; Méndez, Mariano; Markwardt, Craig; van der Klis, Michiel; Chakrabarty, Deepto; Morgan, Ed

2001-10-01

144

Luminosity function of clusters of galaxies  

CERN Multimedia

The composite galaxy luminosity function (hereafter LF) of 39 Abell clusters of galaxies is derived by computing the statistical excess of galaxy counts in the cluster direction with respect to control fields. Due to the wide field coverage of the digitised POSS-II plates, we can measure field counts around each cluster in a fully homogeneous way. Furthermore, the availability of virtually unlimited sky coverage allows us to directly compute the LF errors without having to rely on the estimated variance of the background. The wide field coverage also allows us to derive the LF of the whole cluster, including galaxies located in the cluster outskirts. The global composite LF has a slope alpha ~ -1.1+/-0.2 with minor variations from blue to red filters, and M* ~ -21.7,-22.2,-22.4 mag (H_0=50 km/s/Mpc) in g, r and i filters, respectively. These results are in quite good agreement with several previous determinations and in particular with the LF determined for the inner region of a largely overlapping set of clu...

Paolillo, M; Longo, G; Puddu, E; Gal, R R; Scaramella, R; Djorgovski, S G; De Carvalho, R

2001-01-01

145

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

146

Optical surface brightnesses and radio luminosities of galaxies  

Energy Technology Data Exchange (ETDEWEB)

The relationship between optical surface brightness and radio luminosity is considered for 443 galaxies on the basis of radio emission measurements. It is found that an increase in the relative number of galaxies with high radio luminosities with increasing optical surface brightness is observed not only among elliptical, lenticular, and peculiar galaxies, but also among spiral and irregular galaxies.

Malumian, V.G.

1981-04-01

147

Physics at high luminosity muon colliders and a facility overview  

International Nuclear Information System (INIS)

Physics potentials at future colliders including high luminosity ?+?- 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.

2001-01-01

148

Isotropic Luminosity Indicators in a Complete AGN Sample  

CERN Multimedia

The [O IV] 25.89 micron 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.

Diamond-Stanic, Aleksandar M; Rigby, Jane R

2009-01-01

149

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.

2009-06-10

150

An early separation scheme for the LHC luminosity upgrade  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this thesis we evaluate the potential of the Early Separation Scheme for the Luminosity Upgrade of the Large Hadron Collider (LHC). The main goal of the Early Separation Scheme is to reduce the crossing angle between the proton beams at the collision point in order to increase the luminosity perf...

Sterbini, Guido

151

The energy source of intermediate luminosity optical transients  

CERN Multimedia

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

152

ATLAS Future Plans: Upgrade and the Physics with High Luminosity  

CERN Document Server

ATLAS is planning a series of detector upgrades to cope with increasing instantaneous luminosity and multiple interactions per crossing to ensure that acceptance to new physics and precision measurements are preserved. During the next several years, LHC is expected to collide protons on protons at a center of mass energy up to 14 TeV with luminosities reaching 1 to 2 x 1034 cm^-2 s^-1, accumulating ~100 fb^-1 per year following a Phase 1 Upgrade (2018). The detector upgrades focus on precision tracking and improved trigger capabilities to sustain higher rates. Subsequently, the LHC plans calls for a five-fold increase in instantaneous luminosity, thereby increasing the delivered luminosity to ~3000 fb^-1 by 2030. The increased luminosity will significantly increase the physics reach of ATLAS building on the recent discovery of the Higgs-like boson. The planned detector upgrades and the impact on the ATLAS physics program will be discussed.

Rajagopalan, Srini; The ATLAS collaboration

2012-01-01

153

Upgrade of the D0 luminosity monitor readout system  

Energy Technology Data Exchange (ETDEWEB)

We describe upgrades to the readout system for the D0 Luminosity Monitor. The D0 Luminosity Monitor consists of plastic scintillation detectors with fine-mesh photomultiplier readout that cover the pseudorapidity range 2.7 < |{eta}| < 4.4. 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 D0. The new readout system is based on custom VME electronics that make precise time-of-flight and charge measurements for each luminosity counter. These measurements are used to identify beam crossings with non-diffractive interactions by requiring in-time hits in both the forward and backward luminosity counters. We have also significantly increased signal/noise for the photomultiplier signals by developing a new front-end preamplifier and improving the grounding scheme.

Anderson, John; Bridges, Lloyd; Casey, Brendan; Enari, Yuji; Green, Johnny; Johnson, Marvin; Kwarciany, Rick; Miao, Chyi-Chiang; Partridge, Richard; Yoo, Hwi Dong; Wang,; /Brown U. /Fermilab

2006-12-01

154

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

CERN Multimedia

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

155

Operational experience with the superconducting high-luminosity insertion in the CERN intersecting storage rings (ISR)  

Energy Technology Data Exchange (ETDEWEB)

The eight superconducting quadrupoles and their cryogenic equipment for this insertion were installed in the ISR at the end of 1980. The insertion has been used to assess the problems of running a superconducting insertion in a storage ring as well as to provide high luminosity for physics. The luminosity was increased at intersection 8 by a factor of 7. By means of dedicated collimators and orbit corrections, safe working conditions could be established for the superconducting magnets during injection, accumulation, stable beam periods and when dumping the beams. Quenches were mainly caused by large accidental beam losses. Operating parameters for all standard beam energies, including acceleration to 31.4 GeV/c, have been established. At 26.6 GeV/c, with currents of 30.6 A in ring 1 and 30.3 A in ring 2, a luminosity of 1.4 10/sup 32/ cm/sup -2/s/sup -1/ was obtained in the insertion. This is the highest luminosity reached so far in storage rings and it was obtained during a physics run. Satisfactory beam conditions could also be provided for antiproton physics at 26.6 GeV/c in ISR with both low-..beta.. insertions on, in I1 and I8, respectively.

Billan, J.; Bryant, P.J.; Guignard, G.; Henrichsen, K.N.; Laeger, H.; Lebrun, Ph.; Pichler, S.; Resegotti, L.; Risselada, T.; Tortschanoff, T.

1983-08-01

156

Operational experience with the superconducting high-luminosity insertion in the CERN intersecting storage rings (ISR)  

International Nuclear Information System (INIS)

The eight superconducting quadrupoles and their cryogenic equipment for this insertion were installed in the ISR at the end of 1980. The insertion has been used to assess the problems of running a superconducting insertion in a storage ring as well as to provide high luminosity for physics. The luminosity was increased at intersection 8 by a factor of 7. By means of dedicated collimators and orbit corrections, safe working conditions could be established for the superconducting magnets during injection, accumulation, stable beam periods and when dumping the beams. Quenches were mainly caused by large accidental beam losses. Operating parameters for all standard beam energies, including acceleration to 31.4 GeV/c, have been established. At 26.6 GeV/c, with currents of 30.6 A in ring 1 and 30.3 A in ring 2, a luminosity of 1.4 1032 cm-2s-1 was obtained in the insertion. This is the highest luminosity reached so far in storage rings and it was obtained during a physics run. Satisfactory beam conditions could also be provided for antiproton physics at 26.6 GeV/c in ISR with both low-? insertions on, in I1 and I8, respectively.

1983-01-01

157

Correlations of the IR Luminosity and Eddington Ratio with a Hard X-ray Selected Sample of AGN  

CERN Multimedia

We use the SWIFT Burst Alert Telescope (BAT) sample of hard x-ray selected active galactic nuclei (AGN) with a median redshift of 0.03 and the 2MASS J and K band photometry to examine the correlation of hard x-ray emission to Eddington ratio as well as the relationship of the J and K band nuclear luminosity to the hard x-ray luminosity. The BAT sample is almost unbiased by the effects of obscuration and thus offers the first large unbiased sample for the examination of correlations between different wavelength bands. We find that the near-IR nuclear J and K band luminosity is related to the BAT (14 - 195 keV) luminosity over a factor of $10^3$ in luminosity ($L_{IR} \\approx L_{BAT}^{1.25}$)and thus is unlikely to be due to dust. We also find that the Eddington ratio is proportional to the x-ray luminosity. This new result should be a strong constraint on models of the formation of the broad band continuum.

Mushotzky, R F; McIntosh, D H; Tüller, J

2008-01-01

158

Galactic Ultracompact X-ray Binaries: Empirical Luminosities  

CERN Document Server

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 PCA 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 X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in globular clusters. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few times 10^36 ergs/s in both old field p...

Cartwright, T F; Heinke, C O; Sivakoff, G R; Berger, J J; Gladstone, J C; Ivanova, N

2013-01-01

159

Towards a new LHC Interaction Region design for a luminosity upgrade  

CERN Document Server

After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the low-beta insertions with a higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. Preliminary studies show that, with magnet technology that is expected to be developed by early in the next decade, a factor of 2 to 5 reduction in beta* could be achieved with new insertions, as part of an upgrade aimed at a factor of 10 luminosity increase. In this paper we survey several possible second generation LHC interaction regions designs, which address the expected limitations on LHC performance imposed by the baseline insertions.

Strait, J; Limon, P; Mokhov, N V; Sen, T; Zlobin, A V; Brüning, Oliver Sim; Ostojic, R; Rossi, L; Ruggiero, F; Taylor, T; ten Kate, H; Devred, A; Gupta, R; Harrison, M; Peggs, S; Pilat, F; Caspi, S; Gourlay, S; Sabbi, G

2003-01-01

160

Towards a new LHC interaction region design for a luminosity upgrade  

Energy Technology Data Exchange (ETDEWEB)

After the LHC operates for several years at nominal parameters, it will be necessary to upgrade it for higher luminosity. Replacing the low-{beta} insertions with a higher performance design based on advanced superconducting magnets is one of the most straightforward steps in this direction. Preliminary studies show that, with magnet technology that is expected to be developed by early in the next decade, a factor of 2 to 5 reduction in {beta}* could be achieved with new insertions, as part of an upgrade aimed at a factor of 10 luminosity increase. In this paper we survey several possible second generation LHC interaction regions designs, which address the expected limitations on LHC performance imposed by the baseline insertions.

James Strait et al.

2003-05-29

 
 
 
 
161

Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function  

CERN Document Server

We correct the observed Milky Way satellite luminosity function for luminosity bias using published completeness limits for the Sloan Digital Sky Survey DR5. Assuming that the spatial distribution of Milky Way satellites tracks the subhalos found in the Via Lactea LambdaCDM N-body simulation, we show that there should be between ~300 and ~600 satellites within 400 kpc of the Sun that are brighter than the faintest known dwarf galaxies, and that there may be as many as ~1000, depending on assumptions. By taking into account completeness limits, we show that the radial distribution of known Milky Way dwarfs is consistent with our assumption that the full satellite population tracks that of subhalos. These results alleviate the primary worries associated with the so-called "Missing Satellites Problem" in CDM. We show that future, deep wide-field surveys like SkyMapper, the Dark Energy Survey (DES), PanSTARRS, and the Large Synoptic Survey Telescope (LSST) will deliver a complete census of ultra-faint dwarf satel...

Tollerud, Erik J; Strigari, Louis E; Willman, Beth

2008-01-01

162

Prospects for the high luminosity LHC (ATLAS and CMS)  

CERN Document Server

This presentation reviews the different physic topics which could be accessible with the High-Luminosity LHC program (HL-LHC) with the ATLAS and CMS detectors. An integrated luminosity of 3000 fb-1 at 14 TeV is expected and detectors will have to adapt to severe data-taking conditions. The Higgs boson coupling to fermions/bosons will be measured with precisions reaching the percent level. Expections on Higgs self coupling and vector-vector boson scattering are also reachable with this luminosity. The direct search of heavy resonances or SUSY particles will reach the TeV scale.

Jezequel, S; The ATLAS collaboration

2013-01-01

163

Notes on van der Meer Scan for Absolute Luminosity Measurement  

CERN Multimedia

An absolute luminosity can be measured in an accelerator by sweeping beams transversely across each other in the so called van der Meer scan. We prove that the method can be applied in the general case of arbitrary beam directions and a separation scan plane. A simple method to develop an image of the beam in its transverse plane from spatial distributions of interaction vertexes is also proposed. From the beam images one can determine their overlap and the absolute luminosity. This provides an alternative way of the luminosity measurement during van der Meer scan.

Balagura, Vladislav

2011-01-01

164

Notes on Van der Meer scan for absolute luminosity measurement  

International Nuclear Information System (INIS)

The absolute luminosity can be measured in an accelerator by sweeping beams transversely across each other in the so-called van der Meer scan. We prove that the method can be applied in the general case of arbitrary beam directions and a separation scan plane. A simple method to develop an image of the beam in its transverse plane from spatial distributions of interaction vertexes is also proposed. From the beam images one can determine their overlap and the absolute luminosity. This provides an alternative way of the luminosity measurement during van der Meer scan.

2011-10-21

165

High precision measurements of the luminosity at LEP  

International Nuclear Information System (INIS)

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

1994-07-01

166

Nearby debris disk systems with high fractional luminosity reconsidered  

CERN Multimedia

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

167

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

2006-09-15

168

The spectrometer system for measuring ZEUS luminosity at HERA  

Energy Technology Data Exchange (ETDEWEB)

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.

Helbich, M. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States); Ning, Y. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States); Paganis, S. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States); Ren, Z. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States)]. E-mail: zhenhai@phys.columbia.edu; Schmidke, W.B. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States); Sciulli, F. [Nevis Laboratories, Columbia University, Irvington on Hudson, New York, NY (United States); Schneekloth, U. [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany); Buettner, C. [Max-Planck-Institut fuer Physik, Munich (Germany); Caldwell, A. [Max-Planck-Institut fuer Physik, Muenchen (Germany); Sutiak, J. [Max-Planck-Institut fuer Physik, Munich (Germany)

2006-09-15

169

Deep luminosity function of the globular cluster M13  

Energy Technology Data Exchange (ETDEWEB)

The luminosity function in a field of M13 at 14 core radii has been observed to M(V) = +12.0, and new theoretical, low-mass, stellar models appropriate to M13 are used to convert the function to a mass function which extends to M = 0.18 solar, within a factor of two of brown dwarf masses at this metal abundance. As the number of stars observed in each magnitude bin is still increasing at the limit of the data, the presence of stars with masses lower than 0.18 solar is probable. This result sets an upper limit of 0.18 solar mass for low-mass cutoffs in dynamical models of M13. No single power law mass function fits all the observations. The trend of the data supports the idea of a steep increase in the slope of the mass function for M less than 0.4 solar. The results imply that the total mass in low-mass stars in M13, and by implication elsewhere, is higher than was previously thought. 26 references.

Drukier, G.A.; Fahlman, G.G.; Richter, H.B.; Vandenberg, D.A.

1988-05-01

170

Deep luminosity function of the globular cluster M13  

International Nuclear Information System (INIS)

The luminosity function in a field of M13 at 14 core radii has been observed to M(V) = +12.0, and new theoretical, low-mass, stellar models appropriate to M13 are used to convert the function to a mass function which extends to M = 0.18 solar, within a factor of two of brown dwarf masses at this metal abundance. As the number of stars observed in each magnitude bin is still increasing at the limit of the data, the presence of stars with masses lower than 0.18 solar is probable. This result sets an upper limit of 0.18 solar mass for low-mass cutoffs in dynamical models of M13. No single power law mass function fits all the observations. The trend of the data supports the idea of a steep increase in the slope of the mass function for M less than 0.4 solar. The results imply that the total mass in low-mass stars in M13, and by implication elsewhere, is higher than was previously thought. 26 references.

1988-01-01

171

Experiments on enhancing of electron bunch luminosity in the synchrotron  

International Nuclear Information System (INIS)

[en] To intensify luminosity of a circulating electron bunch the dynamics of transverse sizes of the beam on the flat-top magnetic field of 600 MeV in the PFI AN synchrocyclotron has been studied experimentally. The investigations were carried out both in the absence of and simultaneously in the presence of other disturbance factors of vertical beam size within the range of magnetic field index values from 0.707 to approximately 0.61. As a result of experiment 2.4 mm vertical size is reduced to 0.68 mm and 4 mm radial size is reduced 1.4 times. Reduction of the transverse bunch sizes beyond the areas of coupling resonances results from pulse modulation of the magnetic field index, by decreasing of vertical oscillation wiggle with quantum fluctuation of radiation under effect of inclination of cross section axis of a circulating beam to the horizontal plane and by the decrease of azimuthal asymmetry of the median plane

1977-01-01

172

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

173

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

174

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.)

1983-01-01

175

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

176

Measurement of the absolute luminosity with the ALEPH detector  

International Nuclear Information System (INIS)

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

1992-01-01

177

Layered convection as the origin of Saturn's luminosity anomaly  

CERN Multimedia

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

178

Galaxy morphology, luminosity and environment in the SDSS DR7  

CERN Multimedia

We study the influence of the environment on the evolution of galaxies by investigating the luminosity function (LF) of galaxies of different morphological types at different environmental density levels. We construct the LFs separately for spiral and elliptical galaxies using data from the Sloan Digital Sky Survey (SDSS), correcting the luminosities for the intrinsic absorption. We use the global luminosity density field to define different environments. The smoothed bootstrap method is used to calculate confidence regions of the derived luminosity functions. We find a strong environmental dependency for the LF of elliptical galaxies. The LF of spiral galaxies is almost environment independent, suggesting that spiral galaxy formation mechanisms are similar in different environments. Absorption by the intrinsic dust influences the bright-end of the LF of spiral galaxies. After attenuation correction, the brightest spiral galaxies are still about 0.5 mag less luminous than the brightest elliptical galaxies. De...

Tempel, E; Liivamägi, L J; Tamm, A; Einasto, J; Einasto, M; Müller, V

2010-01-01

179

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

2013-01-01

180

Experience with high luminosity running at the CERN ISR  

International Nuclear Information System (INIS)

[en] 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

1983-03-04

 
 
 
 
181

Evolution of the cluster X-ray luminosity function  

DEFF Research Database (Denmark)

We report measurements of the cluster X-ray luminosity function out to z = 0.8 based on the final sample of 201 galaxy systems from the 160 Square Degree ROSAT Cluster Survey. There is little evidence for any measurable change in cluster abundance out to z similar to 0.6 at luminosities of less than a few times 10(44) h(50)(-2) ergs s(-1) (0.5 - 2.0 keV). However, for 0.6 luminosities above 10(44) h(50)(-2) ergs s(-1), the observed volume densities are significantly lower than those of the present-day population. We quantify this cluster deficit using integrated number counts and a maximum likelihood analysis of the observed luminosity-redshift distribution fit with a model luminosity function. The negative evolution signal is more than 3 sigma regardless of the adopted local luminosity function or cosmological framework. Our results and those from several other surveys independently confirm the presence of evolution. Whereas the bulk of the cluster population does not evolve, the most luminousand presumably most massive structures evolve appreciably between z = 0.8 and the present. Interpreted in the context of hierarchical structure formation, we are probing sufficiently large mass aggregations at sufficiently early times in cosmological history, when the universe has yet to assemble these clusters to present-day volume densities.

Mullis, C.R.; Vikhlinin, A.

2004-01-01

182

Local radio luminosity function of galaxies at 843 MHz  

Energy Technology Data Exchange (ETDEWEB)

Following a previous investigation of the radio luminosity function, two samples of galaxies have been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. These comprise 176 E and SO galaxies, and 21 galaxies with delta <= -45/sup 0/. The resulting local radio luminosity function (LRLF) has been extended to radio powers of approx. 10/sup 18/ WHz/sup -1/ sr/sup -1/. At such low luminosities, the irregular galaxies apparently begin to dominate the LRLF. Spirals on the other hand, continue to be confined to radio powers in the range 10sup(19-22) W Hz/sup -1/ sr/sup -1/. E and SO galaxies appear unimportant to the LRLF at low radio luminosities but behave like similar standard candles above powers of approx. 10sub(22.5) WHz/sup -1/ sr/sup -1/. The most massive SO galaxies appear similar to radio ellipticals, but at lower optical luminosities comparable to those of spirals. In addition SO galaxies resemble early-type spirals closely both in their detection rate and correlation between radio and optical luminosities.

Subrahmanya, C.R.; Harnett, J.I.

1987-03-15

183

The local radio luminosity function of galaxies at 843 MHz  

International Nuclear Information System (INIS)

Following a previous investigation of the radio luminosity function, two samples of galaxies have been observed with the Molonglo Observatory Synthesis Telescope at 843 MHz. These comprise 176 E and SO galaxies, and 21 galaxies with delta 0. The resulting local radio luminosity function (LRLF) has been extended to radio powers of approx. 1018 WHz-1 sr-1. At such low luminosities, the irregular galaxies apparently begin to dominate the LRLF. Spirals on the other hand, continue to be confined to radio powers in the range 10sup(19-22) W Hz-1 sr-1. E and SO galaxies appear unimportant to the LRLF at low radio luminosities but behave like similar standard candles above powers of approx. 10sub(22.5) WHz-1 sr-1. The most massive SO galaxies appear similar to radio ellipticals, but at lower optical luminosities comparable to those of spirals. In addition SO galaxies resemble early-type spirals closely both in their detection rate and correlation between radio and optical luminosities. (author).

1987-01-01

184

The Morphology Dependence of Luminosity Segregation in the Coma Cluster  

CERN Multimedia

We carry out CCD photometry of galaxies in the 5.25 square region centered on Coma cluster down to $M_R=-16.0$, beyond the limit of conventional morphological classification. We use the angular two-point correlation function as well as radial profiles in order to characterize the luminosity segregation. We find strong luminosity segregation for our total sample over the magnitude range of $-20 \\leq M_R \\leq -16$, which is not entirely accounted for in terms of the morphology-density relation that is known to exist only for bright galaxies. We use a single consistent parameter, the degree of luminosity concentration, to parameterize the morphology of galaxies over the wide magnitude range, where both giant and dwarf galaxies are included. Galaxies with high central concentration (HCC) show strong luminosity segregation, i.e. their clustering strength depends strongly on luminosity while those with low central concentration (LCC) show almost no luminosity segregation. Radial density profile shows that brighter ...

Kashikawa, N; Doi, M; Komiyama, Yu; Okamura, S; Shimasaku, K; Yagi, M; Yasuda, N

1998-01-01

185

The Luminosities of Protostars in the Spitzer c2d and Gould Belt Legacy Clouds  

CERN Multimedia

Motivated by the long-standing "luminosity problem" in low-mass star formation whereby protostars are underluminous compared to theoretical expectations, we identify 230 protostars in 18 molecular clouds observed by two Spitzer Space Telescope Legacy surveys of nearby star-forming regions. We compile complete spectral energy distributions, calculate Lbol for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 Lsun - 69 Lsun, and has a mean and median of 4.3 Lsun and 1.3 Lsun, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (Lbol < 0.5 Lsun) 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 um < wavelength < 850 um) and have Lbol underestimated by factors of 2.5 on average, and up to factors of 8-10 in extreme cases. Correcting these underestimates for each source...

Dunham, Michael M; Allen, Lori E; Evans, Neal J; Broekhoven-Fiene, Hannah; Chapman, Nicholas L; Cieza, Lucas A; Gutermuth, Robert A; Harvey, Paul M; Hatchell, Jennifer; Huard, Tracy L; Kirk, Jason M; Matthews, Brenda C; Merin, Bruno; Miller, Jennifer F; Peterson, Dawn E; Spezzi, Loredana

2013-01-01

186

Operation of the ATLAS end-cap calorimeters at sLHC luminosities, an experimental study  

CERN Document Server

The expected increase of luminosity at sLHC by a factor of ten with respect to LHC luminosities has serious consequences for the signal reconstruction, radiation hardness requirements and operations of the ATLAS liquid argon calorimeters (EMEC, HEC, FCAL) in the endcap, respectively forward region. Small modules of each type of calorimeter have been built. The layout and the components used are very close to the ones used in the construction of the ATLAS calorimeter. The goal is to simulate in the high intensity proton beam at IHEP /Protvino the particle impact as expected for ATLAS in sLHC. Depending on the position in pseudorapidity |?|, each forward calorimeter has to cope with a different particle and energy flux. Placing absorber elements in-between the various small calorimeter modules, the particle and energy flux as expected in ATLAS later - given the variation due to |?| and longitudinal position - can be simulated very well.

Ferencei, J; The ATLAS collaboration

2009-01-01

187

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.

2009-07-20

188

Evolution of the Galaxy Luminosity Function at z < 0.3  

CERN Multimedia

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

Loveday, J

2004-01-01

189

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

190

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 multi-variate 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 the population of quasars exhibits strong positive correlation between the radio and optical luminosities. With this correlation, whether intrinsic or observationally induced accounted for, we 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 for the range of R values considered. 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 sample considered.

Singal, J.; Petrosian, V. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory and Stanford University, 382 Via Pueblo Mall, Stanford, CA 94305-4060 (United States); Lawrence, A. [Institute for Astronomy, Scottish Universities Physics Alliance (SUPA), University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Stawarz, L., E-mail: jsingal@stanford.edu [Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5510 (Japan)

2011-12-20

191

A luminosity measurement at LEP using the L3 detector  

International Nuclear Information System (INIS)

[en] 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.)

1996-01-01

192

TOWARD TIGHT GAMMA-RAY BURST LUMINOSITY RELATIONS  

Energy Technology Data Exchange (ETDEWEB)

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 E{sub peak}-{tau}{sub RT}-L to be evidently tighter (at the 2{sigma} confidence level) than its corresponding 2D correlations, i.e., the E{sub peak}-L and {tau}{sub RT}-L correlations. In addition, the coefficients before the logarithms of E{sub peak} and {tau}{sub RT} in the E{sub peak}-{tau}{sub RT}-L correlation are almost exact opposites of each other. Inputting this situation as a prior reduces the relation to L{proportional_to}(E'{sub peak}/{tau}{sub RT}'){sup 0.842{+-}0.064}, where E'{sub peak} and {tau}'{sub 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.

Qi Shi; Lu Tan, E-mail: qishi11@gmail.com, E-mail: t.lu@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-04-20

193

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

194

Magnitude Gap Statistics and the Conditional Luminosity Function  

Science.gov (United States)

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

More, Surhud

2012-12-01

195

The Luminosities of Protostars in the Spitzer c2d and Gould Belt Legacy Clouds  

Science.gov (United States)

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 bol for each source, and study the protostellar luminosity distribution. This distribution extends over three orders of magnitude, from 0.01 L ? to 69 L ?, and has a mean and median of 4.3 L ? and 1.3 L ?, respectively. The distributions are very similar for Class 0 and Class I sources except for an excess of low luminosity (L bol <~ 0.5 L ?) Class I sources compared to Class 0. 100 out of the 230 protostars (43%) lack any available data in the far-infrared and submillimeter (70 ?m 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, Héctor G.; Allen, Lori E.; Evans, Neal J., II; Broekhoven-Fiene, Hannah; Chapman, Nicholas L.; Cieza, Lucas A.; Gutermuth, Robert A.; Harvey, Paul M.; Hatchell, Jennifer; Huard, Tracy L.; Kirk, Jason M.; Matthews, Brenda C.; Merín, Bruno; Miller, Jennifer F.; Peterson, Dawn E.; Spezzi, Loredana

2013-04-01

196

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

197

Evolution in the X-ray Cluster Luminosity Function Revisited  

CERN Multimedia

(Shortened Abstract) We present new X-ray data taken from the ROSAT PSPC pointing archive for 21 clusters in the Einstein Extended Medium Sensitivity Survey (EMSS). We have supplemented these data with new optical follow-up observations found in the literature and overall, 32 of the original 67 z>0.14 EMSS clusters now have new information. Using this improved EMSS sample, we have re-determined the EMSS X-ray Cluster Luminosity Function as a function of redshift. We have removed potential mis-classifications and included our new measurements of the clusters X-ray luminosities and redshifts. We find similar luminosity functions to those originally presented by Henry etal (1992); albeit with two important differences. First, we show that the original low redshift EMSS luminosity function is insufficiently constrained. Secondly, the power law shape of our new determination of the high redshift EMSS luminosity function (z=0.3 to 0.6) has a shallower slope than that seen by Henry etal. We have quantified the degre...

Nichol, R C; Romer, A K; Ulmer, M P; Burke, D J; Collins, C A

1996-01-01

198

Layered convection as the origin of Saturn's luminosity anomaly  

Science.gov (United States)

As the giant planets of our Solar System continue to cool and contract, they radiate more energy than they receive from the Sun. A giant planet's cooling rate, luminosity and temperature at a given age can be determined using the first and second principles of thermodynamics. Measurements of Saturn's infrared luminosity, however, reveal that Saturn is significantly brighter than predicted for its age. This excess luminosity has been attributed to the immiscibility of helium in Saturn's hydrogen-rich envelope, which leads to rains of helium-rich droplets. Existing calculations of Saturn's evolution, however, suggest that the energy released by helium rains might be insufficient to resolve the luminosity puzzle. Here we demonstrate, using semi-analytical models of planetary thermal evolution, that the cooling of Saturn's interior is significantly slower in the presence of layered convection generated--like in Earth's oceans--by a compositional gradient. We find that layered convection can explain Saturn's present luminosity for a wide range of initial energy configurations without invoking any additional energy source. Our findings suggest that the interior structure, composition and thermal evolution of giant planets in our Solar System and beyond may be more complex than the conventional approximation of giant planets as homogeneous adiabatic bodies.

Leconte, Jérémy; Chabrier, Gilles

2013-05-01

199

ATLAS Phase II for the High Luminosity Upgrade  

CERN Multimedia

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 acqui...

Huffman, B T; The ATLAS collaboration

2013-01-01

200

A statistical study of the luminosity gap in galaxy groups  

CERN Multimedia

The luminosity gap between the two brightest members of galaxy groups and clusters is thought to offer a strong test for the models of galaxy formation and evolution. This study focuses on the statistics of the luminosity gap in galaxy groups, in particular fossil groups, e.g. large luminosity gap, in an analogy with the same in a cosmological simulation. We use spectroscopic legacy data of seventh data release (DR7) of SDSS, to extract a volume limited sample of galaxy groups utilizing modified friends-of-friends (mFoF) algorithm. Attention is paid to galaxy groups with the brightest group galaxy (BGG) more luminous than \\Mr = -22. An initial sample of 620 groups in which 109 optical fossil groups, where the luminosity gap exceeds 2 magnitude, were identified. We compare the statistics of the luminosity gap in galaxy groups at low mass range from the SDSS with the same in the Millennium simulations where galaxies are modeled semi-analytically. We show that the BGGs residing in galaxy groups with large lumino...

Tavasoli, Saeed; Koohpaee, Ali; Rahmani, Hadi; Ghanbari, Jamshid

2010-01-01

 
 
 
 
201

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

202

Evolution of Galaxy Luminosity Function Using Photometric Redshifts  

Science.gov (United States)

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 phi* 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.

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

2011-08-01

203

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.

2011-01-01

204

Report of the Working Group on High Luminosities at LEP  

International Nuclear Information System (INIS)

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

1991-01-01

205

Optimization of NLC Luminosity for e-e- Running  

Energy Technology Data Exchange (ETDEWEB)

We examine the optimization of the NLC for e{sup -}e{sup -} running. The dependence of luminosity on the interaction point beta functions {beta}{sub x}, {beta}{sub y}, emittances {epsilon}{sub x}, {epsilon}{sub y}, bunch charge N, and bunch length {sigma}{sub z} are very different for e{sup +}e{sup -} and e{sup -}e{sup -} because disruption reduces the luminosity in e{sup -}e{sup -} rather than increasing it as in e{sup +}e{sup -}. We examine how much luminosity may be regained in e{sup -}e{sup -} by varying these parameters away from optimized at beam e{sup +}e{sup -} values. The results are compared with round beam e{sup -}e{sup -} designs considered in an earlier paper.

Thompson, Kathleen A

2000-11-28

206

Optimization of NLC Luminosity for e-e- Running  

Energy Technology Data Exchange (ETDEWEB)

We examine the optimization of the NLC for e{sup -}e{sup -} running. The dependence of luminosity on the interaction point beta functions {beta}{sub x}, {beta}{sub y}, emittances {epsilon}{sub x}, {epsilon}{sub y}, bunch charge N, and bunch length {sigma}{sub z} are very different for e{sup +}e{sup -} and e{sup -}e{sup -} because disruption reduces the luminosity in e{sup -}e{sup -} rather than increasing it as in e{sup +}e{sup -}. We examine how much luminosity may be regained in e{sup -}e{sup -} by varying these parameters away from optimized flat beam e{sup +}e{sup -} values. The results are compared with round beam e{sup -}e{sup -} designs considered in an earlier paper.

Thompson, Kathleen A

2000-11-28

207

The UV luminosity function of nearby clusters of galaxies  

CERN Multimedia

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

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

2003-01-01

208

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.

2013-01-01

209

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

210

LUMINOSITY OPTIMIZATION USING AUTOMATED IR STEERING AT RHIC.  

Energy Technology Data Exchange (ETDEWEB)

The goal of the RHIC 2004 Au-Au run was to maximize the achieved integrated luminosity. One way is to increase beam currents and minimize beam transverse emittances. Another important ingredient is the minimization of time spent on activities postponing the declaration of ''physics conditions'', i.e. stable beam conditions allowing the experimental detectors to take data. Since collision rates are particularly high in the beginning of the store the integrated luminosity benefits considerably from any minute saved early in the store. In the RHIC run 2004 a new IR steering application uses luminosity monitor signals as a feedback for a fully automated steering procedure. This report gives an overview of the used procedure and summarizes the achieved results.

DREES,A.D' OTTAVIO,T.

2004-07-05

211

Luminosity and Redshift dependence of quasar spectral properties  

Energy Technology Data Exchange (ETDEWEB)

Using a large sample of quasar spectra from the SDSS, we examine the composite spectral trends of quasars as functions of both redshift and luminosity, independently of one another. Aside from the well known Baldwin effect (BE)--the decrease of line equivalent width with luminosity--the average spectral properties are remarkably similar. Host galaxy contamination and the BE are the primary causes for apparent changes in the average spectral slope of the quasars. The BE is detected for most emission lines, including the Balmer lines, but with several exceptions including NV1240A. Emission line shifts of several lines are associated with the BE. The BE is mainly a function of luminosity, but also partly a function of redshift in that line equivalent widths become stronger with redshift. Some of the complex iron features change with redshift, particularly near the small blue bump region.

Daniel E. Vanden Berk et al.

2004-03-09

212

Jet Luminosity from Neutrino-Dominated Accretion Flows in GRBs  

CERN Multimedia

A hyperaccretion disk around a stellar-mass black hole is a plausible model for the central engine that powers gamma-ray bursts (GRBs). We estimate the luminosity of a jet driven by magnetohydrodynamic processes such as the Blandford-Znajek (BZ) mechanism as a function of mass accretion rate, the black hole mass, and other accretion parameters. We show that the jet is most efficient when the accretion flow is cooled via optically-thin neutrino emission, and that its luminosity is much larger than the energy deposition rate through neutrino annihilation provided that the black hole is spinning rapidly enough. Also, we find a significant jump in the jet luminosity at the transition mass accretion rate between the advection dominated accretion flow (ADAF) regime and the neutrino-dominated accretion flow (NDAF) regime. This may cause the large variability observed in the prompt emission of GRBs.

Kawanaka, Norita

2013-01-01

213

RHIC PERFORMANCE AND PLANS TOWARDS HIGHER LUMINOSITY AND HIGHER POLARIZATION.  

Energy Technology Data Exchange (ETDEWEB)

The Relativistic Heavy Ion Collider (RHIC), the first hadron accelerator and collider consisting of two independent rings, has completed its fourth year of operation since commissioning in 1999. RHIC is designed to provide luminosity over a wide range of beam energies and species, including heavy ions, polarized protons, and asymmetric beam collisions. RHIC has produced physics data at four experiments in runs that include gold-on-gold collisions at various beam energies (9.8, 31, 65, and 100 GeV/u), high-energy polarized proton-proton collisions (100 GeV), and deuteron-gold collisions (100 GeV/u). We review recent machine performance for high-luminosity gold-gold operations and polarized proton operations, including causes and solutions for known operational limits. Plans and progress for luminosity and polarization improvements, electron cooling, and the electron-ion collider eRHIC are discussed.

SATOGATA,T.

2004-07-05

214

On jets and luminosity function of GRBs associated with supernovae  

Science.gov (United States)

If Gamma-ray Bursts (GRBs) are generally associated with supernovae, a relatively wide intrinsic luminosity function is implied. If it is assumed that the intrinsic luminosity function of GRBs is a power-law: ?(L)~L-?, data from the BATSE 4B catalog can be used to constrain slope index ? and the dynamic range width Log Lmax/Lmin Using a K-S test comparison with the observational Log N-Log P, we find constraints on the GRB fireball model, GRB jets. We find the acceptable dynamic range for 102luminosity function provided by a purely special relativistic effect on a jet would not dominate. .

Che, H.

2000-06-01

215

The bulge luminosity for low-mass black holes  

CERN Document Server

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

Jiang, Yanfei; Ho, Luis

2011-01-01

216

Mid-infrared properties of nearby low-luminosity AGN at high angular resolution  

CERN Document Server

High spatial resolution mid-infrared (MIR) 12 \\mum continuum imaging of low-luminosity active galactic nuclei (LLAGN) obtained by VLT/VISIR is presented. The goal of this investigation is to determine if the nuclear MIR emission of LLAGN is consistent with the existence of a dusty obscuring torus. A sample of 17 nearby LLAGN was selected and combined with archival VISIR data of 9 additional LLAGN with available X-ray measurements. Of the 17 observed LLAGN, 7 are detected, while upper limits are derived for the 10 non-detections. All detections except NGC 3125 appear point-like on a spatial scale of \\sim 0.35". The detections do not significantly deviate from the known MIR-X-ray correlation but extend it by a factor of \\sim 10 down to luminosities < 10^41 erg/s with a narrow scatter. The latter is dominated by the uncertainties in the X-ray luminosity. Interestingly, a similar correlation with comparable slope but with a normalization differing by \\sim 2.6 orders of magnitude has been found for local starbu...

Asmus, D; Smette, A; Hönig, S F; Duschl, W J

2011-01-01

217

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

218

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

CERN Multimedia

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

219

The Ks-band Luminosity and Stellar Mass Functions of Galaxies in z~1 Clusters  

CERN Multimedia

We present the near-infrared (Ks-band) luminosity function of galaxies in two z~1 cluster candidates, 3C336 and Q1335+28. A third cluster, 3C289, was observed but found to be contaminated by a foreground system. Our wide field imaging data reach to Ks=20.5 (5sigma), corresponding to ~M*+2.7 with respect to the passive evolution. The near-infrared luminosity traces the stellar mass of a galaxy due to its small sensitivity to the recent star formation history. Thus the luminosity function can be transformed to the stellar mass function of galaxies using the $J-K$ colours with only a small correction (factor>1) in the cluster core, it seems that the galaxy formation processes (both star formation and mass assembly) are strongly accerelated in dense environments and has been largely completed by z=1. We investigate whether the epoch of mass assembly of massive cluster galaxies is earlier than that predicted by the hierarchical galaxy formation models. These models predict the increase of characteristic mass by mo...

Kodama, T; Kodama, Tadayuki

2003-01-01

220

The Dependence of Type Ia Supernova Luminosities on their Host Galaxies  

CERN Multimedia

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

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

2010-01-01

 
 
 
 
221

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

222

MODELING THE RED SEQUENCE: HIERARCHICAL GROWTH YET SLOW LUMINOSITY EVOLUTION  

Energy Technology Data Exchange (ETDEWEB)

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

Skelton, Rosalind E. [Department of Astronomy, Yale University, 260 Whitney Avenue, New Haven, CT 06511 (United States); Bell, Eric F. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042 (United States); Somerville, Rachel S., E-mail: ros.skelton@yale.edu [Department of Physics and Astronomy, Rutgers, State University of New Jersey, 136 Frelinghuysen Road, Piscataway, NJ 08854 (United States)

2012-07-01

223

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

1994-07-01

224

Does Amati Relation Depend on Luminosity of GRB's Host Galaxies?  

CERN Multimedia

In order to test systematic of the Amati relation, the 24 long-duration GRBs with firmly determined $E_{\\gamma,\\mathrm{iso}}$ and $E_{\\mathrm p}$ are separated into two sub-groups according to B-band luminosity of their host galaxies. The Amati relations in the two subgroups are found to be in agreement with each other within uncertainties. Taking into account of the well established luminosity - metallicity relation of galaxies, no strong evolution of the Amati relation with GRB's environment metallicity is implied in this study.

Wang, Jing; Qiu, Yu-lei

2007-01-01

225

Beam-beam interaction: luminosity, tails, and noise  

Energy Technology Data Exchange (ETDEWEB)

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.

Seeman, J.T.

1983-07-01

226

Electron-positron annihilation at high luminosity colliding beams  

International Nuclear Information System (INIS)

[en] Experiments are discussed, which can be carried out at the electron-positron storage rings with increased luminosity (up to 1034 cm-2 sec-1) and corresponding improvement of detectors at total energy region up to 10 GeV. This improvement of the experimental conditions may provide valuable physical information from the theoretical point of view. The comparison is made with analogous experimental possibilities of the projected high energy e+e- storage rings with luminosity up to 1032 cm-2 sec-1

1977-01-01

227

Parameter Space for the LHC High-Luminosity Upgrade  

CERN Multimedia

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

228

Upgrade of ATLAS for high luminosity at the SLHC  

CERN Multimedia

While the LHC is close to its startup, plans are already advancing for an upgrade to about ten times the LHC luminosity in the mid of the next decade. This upgrade project is called the Super-LHC or sLHC. Coping with the high instantaneous and integrated luminosity will require many changes to the ATLAS detector. R&D work is developing rapidly for an all-new inner tracker, for modifications in the calorimeters and the muon system as well as for an improved trigger. This article summarizes the environment expected at the sLHC and the status of the upgrade concepts to the ATLAS detector.

Richter, Rob

2008-01-01

229

Radiation damage to scintillator in the D0 luminosity monitor  

Energy Technology Data Exchange (ETDEWEB)

We report the result of evaluating radiation damage to Bicron BC408 plastic scintillator used in the D0 Luminosity Monitor during Run IIa. The Luminosity Monitor provides pseudo-rapidity coverage over the range 2.7 < |{eta}| < 4.4, with the radiation dose in Run IIa estimated to be 0.5 MRad for the region closest to the beams. We find the light yield is degraded by 10-15% due to radiation damage by comparing new and old scintillator in four observables: (1) visual inspection, (2) optical transmittance, (3) response to the radioactive source of {sup 90}Sr and (4) light yield for cosmic rays.

Casey, Brendan; DeVaughan, Kayle; /Brown U. /Nebraska U.; Enari, Yuji; Partridge, Richard; /Brown U.; Yacoob, Sahal; /Northwestern U.

2006-12-01

230

The Nuclear Infrared Emission of Low-Luminosity AGN  

CERN Document Server

We have obtained high-resolution mid-infrared (MIR) imaging, nuclear spectral energy distributions (SEDs) and archival Spitzer spectra for 22 low-luminosity active galactic nuclei (LLAGN; L_bol < 5 x 10^42 erg/s). Infrared (IR) observations may advance our understanding of the accretion flows in LLAGN, the fate of the obscuring torus at low accretion rates, and, perhaps, the star formation histories of these objects. However, while comprehensively studied in higher-luminosity Seyferts and quasars, the nuclear IR properties of LLAGN have not yet been well-determined. In these proceedings we summarise the results for the LLAGN at the relatively high-luminosity, high-Eddington ratio end of the sample. Strong, compact nuclear sources are visible in the MIR images of these objects, with luminosities consistent with or slightly in execss of that predicted by the standard MIR/X-ray relation. Their broadband nuclear SEDs are diverse; some resemble typical Seyfert nuclei, while others possess less of a well-defined...

Mason, R E; Packham, C; Alonso-Herrero, A; Levenson, N A; Radomski, J; Almeida, C Ramos; Colina, L; Elitzur, M; Aretxaga, I; Roche, P F; Oi, N

2012-01-01

231

Indicators of Intrinsic AGN Luminosity: a Multi-Wavelength Approach  

CERN Document Server

We consider five indicators for intrinsic AGN luminosity: the luminosities of the [OIII]$\\lambda$5007 line, the [OIV]25.89$\\mu$m line, the mid-infrared (MIR) continuum emission by the torus, and the radio and hard X-ray (E $>$ 10keV) continuum emission. We compare these different proxies using two complete samples of low-redshift type 2 AGN selected in a homogeneous way based on different indicators: an optically selected [OIII] sample and a mid-infrared selected 12$\\mu$m sample. We examine the correlations between all five different proxies, and find better agreement for the [OIV], MIR, and [OIII] luminosities than for the hard X-ray and radio luminosities. Next, we compare the ratios of the fluxes of the different proxies to their values in unobscured Type 1 AGN. The agreement is best for the ratio of the [OIV] and MIR fluxes, while the ratios of the hard X-ray to [OIII], [OIV], and MIR fluxes are systematically low by about an order-of-magnitude in the Type 2 AGN, indicating that hard X-ray selected sample...

LaMassa, Stephanie M; Ptak, Andrew; Martins, Lucimara; Wild, Vivienne; Sonnentrucker, Paule; Tremonti, Christy

2010-01-01

232

The Luminosity Function and Formation Rate History of GRBs  

CERN Multimedia

The isotropic luminosity function (LF) and formation rate history (FRH) of long GRBs is by the first time constrained by using jointly both the observed GRB peak-flux and redshift distributions. Our results support an evolving LF and a FRH that keeps increasing after z=2. We discuss some interesting implications related to these results.

Firmani, C; Ghisellini, G; Tutukov, A V

2005-01-01

233

Separation and crossing scheme, operation with high luminosity in 2010  

CERN Multimedia

First experience with colliding beams has been collected during the 2009 LHC run and some of the necessary procedures for high performance operation have been tested. These will be critically examined and serve as input to define strategies for operation at higher energies and higher luminosities in 2010.

Herr, W

2010-01-01

234

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.

1992-01-01

235

Vertex and Track Reconstruction and Luminosity Monitoring at LHCb  

CERN Multimedia

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

Wang, Jianchun

2007-01-01

236

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

237

Vector and Tensor Contributions to the Luminosity Distance  

CERN Multimedia

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

Di Dio, Enea

2012-01-01

238

Studies of high luminosity, high disruption beam-beam interactions  

Energy Technology Data Exchange (ETDEWEB)

The e+ e- linac-on-ring collider concept requires special attention due to the highly asymmetric nature of the beam-beam interaction. A brief review of recent studies is presented followed by some specific offset collision studies. Luminosity as a function of offset is also presented.

Boyce, James

1991-02-01

239

Updating quasar bolometric luminosity corrections. II. Infrared bolometric corrections  

CERN Multimedia

We present infrared bolometric luminosity corrections derived from the detailed spectral energy distributions of 62 bright quasars of low- to moderate-redshift (z=0.03-1.4). At 1.5, 2, 3, 7, 12, 15, and 24 microns we provide bolometric corrections of the mathematical forms L_iso=\\zeta \\lambda L_\\lambda and log(L_iso)=A+B log(\\lambda L_\\lambda). Bolometric corrections for radio-loud and radio-quiet objects are consistent within 95% confidence intervals, so we do not separate them. Bolometric luminosities estimated using these corrections are typically smaller than those derived from some commonly used in the literature. We investigate the possibility of a luminosity dependent bolometric correction and find that, while the data are consistent with such a correction, the dispersion is too large and the luminosity range too small to warrant such a detailed interpretation. Bolometric corrections at 1.5 $\\mu$m are appropriate for objects with properties that fall in the range log(L_bol)=45.4-47.3 and bolometric cor...

Runnoe, Jessie C; Shang, Zhaohui

2012-01-01

240

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

 
 
 
 
241

Determination of the absolute luminosity at the LHC  

International Nuclear Information System (INIS)

[en] 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

2010-01-01

242

DISK GALAXIES WITH BROKEN LUMINOSITY PROFILES FROM COSMOLOGICAL SIMULATIONS  

International Nuclear Information System (INIS)

We present smoothed particle hydrodynamics cosmological simulations of the formation of three disk galaxies with a detailed treatment of chemical evolution and cooling. The resulting galaxies have properties compatible with observations: relatively high disk-to-total ratios, thin stellar disks, and good agreement with the Tully-Fisher and the luminosity-size relations. They present a break in the luminosity profile at 3.0 ± 0.5 disk scale lengths while showing an exponential mass profile without any apparent breaks, which is in line with recent observational results. Since the stellar mass profile is exponential, only differences in the stellar populations can be the cause of the luminosity break. Although we find a cutoff for the star formation rate (SFR) imposed by a density threshold in our star formation model, it does not coincide with the luminosity break and is located at 4.3 ± 0.4 disk scale lengths, with star formation going on between both radii. The color profiles and the age profiles are 'U-shaped', with the minimum for both profiles located approximately at the break radius. The SFR to stellar mass ratio increases until the break, explaining the coincidence of the break with the minimum of the age profile. Beyond the break, we find a steep decline in the gas density and, consequently, a decline in the SFR and redder colors. We show that most stars (64%-78%) in the outer disk originate in the inner disk and afterward migrate there. Such stellar migrations are likely the main origin of the U-shaped age profile and, therefore, of the luminosity break.

2009-11-10

243

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.)

1979-01-01

244

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

Science.gov (United States)

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 int 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.; Dunham, Michael M.

2012-10-01

245

Relativistic effects on the observed AGN luminosity distribution  

CERN Document Server

Recently Zhang (2005) has proposed a model to account for the well established effect that the fraction of type-II AGNs is anti-correlated with the observed X-ray luminosity; the model consists of an X-ray emitting accretion disk coaligned to the dusty torus within the standard AGN unification model. In this paper the model is refined by including relativistic effects of the observed X-ray radiations from the vicinity of the supermassive black hole in an AGN. The relativistic corrections improve the combined fitting results of the observed luminosity distribution and the type-II AGN fraction, though the improvement is not significant. The type-II AGN fraction prefers non- or mildly spinning black hole cases and rules out the extremely spinning case.

Liu, Y; Zhang, X L; Liu, Yuan; Zhang, Shuang Nan; Zhang, Xiao Ling

2006-01-01

246

Luminosity Measurement at ATLAS with a Scintillating Fiber Tracker  

CERN Multimedia

We are reporting about a scintillating fiber tracking detector which is proposed for a precise determination of the absolute luminosity of the CERN LHC at interaction point 1 where the ATLAS experiment is located. The detector needs to track protons elastically scattered under micro-radian angles in direct vicinity to the LHC beam. It is based on square shaped scintillating plastic fibers read out by multi-anode photomultiplier tubes and is housed in Roman Pots. We describe the design and construction of prototype detectors and the results of two beam test experiments carried out at DESY and at CERN. The excellent detector performance established in these tests validates the detector design and supports the feasibility of the proposed challenging method of luminosity measurement. All results from the CERN beam test should be considered as preliminary.

Ask, S

2007-01-01

247

Structure and Luminosity of Neutrino-cooled Accretion Disks  

CERN Multimedia

Neutrino-cooled hyperaccretion disks around stellar mass black holes are plausible candidates for the central engine of gamma-ray bursts. We calculate the one-dimensional structure and the annihilation luminosity of such disks. The neutrino optical depth is of crucial importance in determining the neutrino cooling rate and is in turn dependent on the electron fraction, the free nucleon fraction, and the electron degeneracy, with given density and temperature of the disk matter. We construct a bridging formula for the electron fraction that works for various neutrino optical depths, and give exact definitions for the free proton fraction and free neutron fraction. We show that the electron degeneracy has important effects in the sense that it enlarges the absorption optical depth for neutrinos, and it along with the neutronization processes favored by high temperature cause the electron fraction to drop to be below 0.1 in the inner region of the disk. The resulting neutrino annihilation luminosity is considera...

Liu, T; Xue, L; Lu, J F; Liu, Tong; Gu, Wei-Min; Xue, Li; Lu, Ju-Fu

2007-01-01

248

On the kinematic deconvolution of the local neighbourhood luminosity function  

CERN Multimedia

A method for inverting the statistical star counts equation, including proper motions, is presented; in order to break the degeneracy in that equation it uses the supplementary constraints required by dynamical consistency. The inversion gives access to both the kinematics and the luminosity function of each population in three r\\'egimes: the singular ellipsoid, the constant ratio Schwarzschild ellipsoid plane parallel models and the epicyclic model. This more realistic model is taylored to account for local neighbourhood density and velocity distribution. The first model is fully investigated both analytically and via means of a non-parametric inversion technique, while the second model is shown to be formally its equivalent. The effect of noise and incompleteness in apparent magnitude is investigated. The third model is investigated via a 5D+2D non-parametric inversion technique where positivity of the underlying luminosity function is explicitely accounted for. It is argued that its future application to d...

Pichon, C

2002-01-01

249

Massive black holes in stellar systems: 'quiescent' accretion and luminosity  

CERN Multimedia

Only a small fraction of local galaxies harbor an accreting black hole, classified as an active galactic nucleus (AGN). However, many stellar systems are plausibly expected to host black holes, from globular clusters to nuclear star clusters, to massive galaxies. The mere presence of stars in the vicinity of a black hole provides a source of fuel via mass loss of evolved stars. In this paper we assess the expected luminosities of black holes embedded in stellar systems of different sizes and properties, spanning a large range of masses. We model the distribution of stars and derive the amount of gas available to a central black hole through a geometrical model. We estimate the luminosity of the black holes under simple, but physically grounded, assumptions on the accretion flow. Finally we discuss the detectability of â??quiescentâ?? black holes in the local Universe.

Volonteri, Marta; Campbell, Duncan; Mateo, Mario

2010-01-01

250

Effect of a magnetic field on solar luminosity  

Energy Technology Data Exchange (ETDEWEB)

A simple model of the sun in the presence of different interior magnetic field configurations (purely poloidal field, a general magnetic field having both poloidal and toroidal components, and a toroidal field) has been computed. The effects of these three types of magnetic field on the luminosity, radius, and effective temperature have been calculated. It is found that, although there is a change in luminosity of the configuration, the change in effective solar temperature depends mainly on the change in radius. Further, it is found that it is the toroidal magnetic field component that tends to reduce the effective temperature of the Sun. The possible effect of changes in the magnetic field profile during the period of presolar activity and postsolar activity is discussed.

Tandon, J.N.; Das, M.K.

1982-09-01

251

Can C IV emission be used as a luminosity indicator  

Energy Technology Data Exchange (ETDEWEB)

A careful examination is made of the claims of previous authors that the equivalent width of emission lines such as CIV in QSOs can be used as an indicator of the luminosity of the QSO, and also of the alternative claim that the line flux may be useful as a 'standard candle'. It is shown that the competing claims arise from different approaches to the statistical analysis. It is also shown that the observed correlation between emission-line equivalent width Wsub(lambda) and continuum luminosity L may be chiefly due to the variability of QSOs with flat radio spectra, for which the correlation is most pronounced. Objects so prone to vary hardly make the best 'standard candles'.

Murdoch, H.S. (Sydney Univ. (Australia). School of Physics)

1983-03-01

252

Description of a nuclear interaction in the Keldysh diagram technique and the problem of neutrino luminosity of neutron stars  

International Nuclear Information System (INIS)

The Keldysh diagram technique has been formulated for description of equilibrium and nonequilibrium nuclear systems. A nuclear interaction is constructed on the basis of the theory of finite Fermi systems. The formalism is applied to calculation of the probabilities of various processes. The possibilities of the proposed approach are demonstrated in calculation of the luminosity of the principal reactions which contribute to the cooling of neutron stars. The luminosity is calculated for the process nn?npenu-bar, which incurs in a dense nucleon medium very differently than in a rarefied medium. The dependence of the luminosity of the nucleon--nucleon correlation factor is analyzed. The formalism is applied to systems with pairing. The contribution to the luminosity of the reactions n/sub pa/?n?nu-bar and p/sub pa/?p?nu-bar, which are possible only in the presence of nucleon pairing, is calculated. The consequences of the results in the scenario of neutron-star cooling are discussed

1987-01-01

253

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

254

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

255

Optimization of the Luminosity Spectrum in the NLC  

Energy Technology Data Exchange (ETDEWEB)

The energy spectrum of electrons at the interaction point of a linear collider is determined largely by the beamstrahlung spectrum. The beamstrahlung spectrum in turn is sensitive to the design parameters at the interaction point. In this paper we examine the optimization of the luminosity spectrum for discovery and detailed exploration of various physics processes of interest in the NLC, in particular, top and stop pair production, and a class of processes occurring via W-W scattering.

Thompson, Kathleen A

1999-05-11

256

Physics potential and experimental challenges of the LHC luminosity upgrade  

CERN Multimedia

We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 10**35 cm-2s-1. The detector R&D needed to operate ATLAS and CMS in a very high radiation environment and the expected detector performance are discussed. A few examples of the increased physics potential are given, ranging from precise measurements within the Standard Model (in particular in the Higgs sector) to the discovery reach for several New Physics processes

Gianotti, F; Virdee, Tejinder S

2005-01-01

257

LHC Luminosity calibration using the Longitudinal Density Monitor  

CERN Document Server

The present note describes how data measured with the LHC Longitudinal Density Monitor (LDM) can contribute to the 2012-2013 LHC luminosity calibration experiments. More specifically, LDM data can provide an estimation of the ghost fraction fghost and satellite fraction fsat needed for the normalisation of bunch populations. After a concise description of the LDM data treatment, the key quantities of interest are derived and commented. Finally, a description of the LDM analysis products is given.

Boccardi, A; Ferro-Luzzi, M; Mazzoni, S

2013-01-01

258

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

259

A new CMS pixel detector for the LHC luminosity upgrade  

CERN Multimedia

The CMS inner pixel detector system is planned to be replaced during the first phase of the LHC luminosity upgrade. The plans foresee an ultra low mass system with four barrel layers and three disks on either end. With the expected increase in particle rates, the electronic readout chain will be changed for fast digital signals. An overview of the envisaged design options for the upgraded CMS pixel detector is given, as well as estimates of the tracking and vertexing performance.

Favaro, Carlotta

2011-01-01

260

Semiconductor materials and detectors for future very high luminosity colliders  

CERN Multimedia

Recent results from the CERN RD50 Collaboration for the development of radiation-hard detectors for the LHC upgrade (Super-LHC) and in general for very high luminosity colliders are reviewed, summarized and discussed. Particularly, the attention is focused on emerging technologies (Czochralski and Magnetic Czochralski silicon, thinned detectors, highly doped thin epitaxial layer on Czochralski substrate, pre-irradiated silicon, p-type substrate devices) and new detector structures (3D, 3D-STC, Semi-3D, and Stripixel).

Candelori, A

2005-01-01

 
 
 
 
261

An absolute luminosity monitor for the LHCb experiment  

International Nuclear Information System (INIS)

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

2007-12-01

262

The Luminosity Function of Galaxies in the Hercules Cluster  

CERN Multimedia

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

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

2004-01-01

263

The z = 5 Quasar Luminosity Function from SDSS Stripe 82  

Science.gov (United States)

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 MMT and Magellan telescopes. We construct a well-defined sample of 4.7 MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona. This paper also includes data gathered with the 6.5 m Magellan telescopes located at Las Campanas Observatory, Chile.

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

2013-05-01

264

Discriminating different models of luminosity-redshift distribution  

CERN Multimedia

The beginning of the cosmological phase bearing the direct kinematic imprints of supernovae dimming may significantly vary within different models of late-time cosmology, even if such models are able to fit present SNe data at a comparable level of statistical accuracy. This effect -- useful in principle to discriminate among different physical interpretations of the luminosity-redshift relation -- is illustrated here with a pedagogical example based on the LTB geometry.

Cosmai, L; Gasperini, M; Tedesco, L

2013-01-01

265

Discriminating different models of luminosity–redshift distribution  

International Nuclear Information System (INIS)

The beginning of the cosmological phase bearing the direct kinematic imprints of supernovae (SNe) dimming may significantly vary within different models of late-time cosmology, even if such models are able to fit present SNe data at a comparable level of statistical accuracy. This effect—useful in principle to discriminate among different physical interpretations of the luminosity–redshift relation—is illustrated here with a pedagogical example based on the Lemaître–Tolman–Bondi geometry. (paper)

2013-05-07

266

Physics potential and experimental challenges of the LHC luminosity upgrade  

International Nuclear Information System (INIS)

We discuss the physics potential and the experimental challenges of an upgraded LHC running at an instantaneous luminosity of 1035 cm-2s-1. The detector R and D needed to operate ATLAS and CMS in a very high radiation environment and the expected detector performance are discussed. A few examples of the increased physics potential are given, ranging from precise measurements within the Standard Model (in particular in the Higgs sector) to the discovery reach for several New Physics processes. (orig.)

2004-01-01

267

The VIMOS VLT deep survey. The ultraviolet galaxy luminosity function and luminosity density at 3 ? z ? 4  

Science.gov (United States)

Aims:We study the luminosity function of the high-redshift galaxy population with redshifts 3? z ? 4 using a purely I-band magnitude-selected spectroscopic sample obtained in the framework of the VIMOS VLT Deep Survey (VVDS). Methods: We determine the luminosity function from the VVDS, taking care to add as few assumptions and as simple corrections as possible, and compare our results with those obtained from photometric studies, based on Lyman-break selections or photometric-redshift measurements. Results: We find that in the redshift range 3? z ? 4, the VVDS luminosity function is parameterized by ?^*=1.24+0.48-0.50×10-3 mag-1 Mpc-3 and M^*=-21.49+0.19-0.19, assuming a slope ?=-1.4 consistent with most previous studies. While ?* is comparable to previously found values, M* is significantly brighter by about 0.5 mag at least. Using the conservative slope ?=-1.4, we find a luminosity density at 1700 Å L1700(M<-18.5)=2.4×1019 W Mpc-3 and L1700Total=3.1×1019 W Mpc-3, comparable to that estimated in other studies. Conclusions: .The unexpectedly large number of very bright galaxies found in the VVDS indicates that the color-selection and photometric-redshift techniques that are generally used to build high-redshift galaxy samples may be affected by a significant fraction of color-measurement failures or by incomplete modelling of the mix of stellar emission, AGN contribution, dust absorption and intergalactic extinction assumed to identify high-redshift galaxies, making pure magnitude selection better able to trace the full population. Because of the difficulty to identify all low-luminosity galaxies in a spectroscopic survey, the luminosity density could still be significantly underestimated. We also find that the relative contribution of the most luminous galaxies compared to the fainter ones is at least twice as large in the VVDS compared to former estimates. Therefore, the VVDS paints a quite different picture of the role of the most actively star-forming galaxies in the history of star formation. Based on observations collected at the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007(A). Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

Paltani, S.; Le Fèvre, O.; Ilbert, O.; Arnouts, S.; Bardelli, S.; Tresse, L.; Zamorani, G.; Zucca, E.; Bottini, D.; Garilli, B.; Le Brun, V.; Maccagni, D.; Picat, J.-P.; Scaramella, R.; Scodeggio, M.; Vettolani, G.; Zanichelli, A.; Adami, C.; Bolzonella, M.; Cappi, A.; Charlot, S.; Ciliegi, P.; Contini, T.; Foucaud, S.; Franzetti, P.; Gavignaud, I.; Guzzo, L.; Iovino, A.; McCracken, H. J.; Marano, B.; Marinoni, C.; Mazure, A.; Meneux, B.; Merighi, R.; Pellò, R.; Pollo, A.; Pozzetti, L.; Radovich, M.; Bondi, M.; Bongiorno, A.; Brinchmann, J.; Cucciati, O.; de la Torre, S.; Lamareille, F.; Mellier, Y.; Merluzzi, P.; Temporin, S.; Vergani, D.; Walcher, C. J.

2007-03-01

268

The Main-Sequence Luminosity Function of M13  

Science.gov (United States)

The color-magnitude diagram and the main-sequence luminosity function of the globular cluster M13 have been investigated. While those clusters observed by the Hubble Space Telescope (HST) show a shallow luminosity function for low-mass stars, M13 has been known to have a very steep gradient toward the faint end. To understand this seemingly unique characteristic of M13, we carried out deep BV CCD observations. The observed field of nearly 56 arcmin2 is located approximately 12' from the cluster center. Our (B-V)-V color-magnitude diagram has the main sequence extended to the detection limit at V~24.5 mag. It is apparent that there is a significant population of unexpected field stars below V~22.5, which cannot be accounted for by photometric errors. When these field stars are eliminated, the derived luminosity function of M13 shows a much shallower slope at the faint end, just like other Galactic globular clusters studied by HST observations.

Yim, Hong-Suh; Byun, Yong-Ik; Sohn, Young-Jong; Chun, Mun-Suk

2000-08-01

269

Concerning the Slope of the Cepheid Period-Luminosity Relation  

CERN Document Server

We discuss the impact of possible differences in the slope of the Cepheid Period-Luminosity relation on the determination of extragalactic distances in the context of recent studies that suggest changes in this slope. We show that the Wesenheit function W = V - R x ((V-I), widely used for the determination of Cepheid distances, is expected to be highly insensitive to changes in the slope of the underlying (monochromatic) Period-Luminosity (PL) relations. This occurs because the reddening trajectories in the color-magnitude plane are closely parallel to lines of constant period. As a result W-based Period-Luminosity relations have extremely low residual dispersion, which is because differential (and total line-of-sight) reddening is eliminated in the definition of W and the residual scatter due to a star's intrinsic color/position within the Cepheid is also largely insensitive to W. Basic equations are presented and graphically illustrated, showing the insensitivity of W to changes in the monochromatic PL rela...

Madore, Barry F

2009-01-01

270

Parallax and Luminosity Measurements of an L Subdwarf  

CERN Multimedia

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

271

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

272

Luminosity limits on white dwarfs in a Galactic shroud  

CERN Document Server

We place observational constraints on a recently proposed Galactic population, dubbed the shroud (Gyuk & Gates 1999, Gates & Gyuk 2001). The shroud would be a very thick Galactic disk of low luminosity objects, most likely old white dwarfs, proposed to explain the optical depth seen in microlensing surveys towards the Magellanic clouds. The shroud is a simple alternative to the lenses being distributed in a classical, near-spherical dark halo; the advantage of the shroud is that it would compose only a fraction of a dark halo's total mass. In this paper, we argue that stars of the Galactic shroud would be detectable in the recent proper motion survey of Oppenheimer et al. (2001) if their absolute luminosities were brighter than M_R_59F = 19.4 or approximately M_V = 18.6. We adopt a range of simple models of the shroud's kinematics and morphology, and the colours and luminosities of its white dwarfs; via Monte-Carlo simulations, we predict the numbers expected in the Oppenheimer et al. survey, which wo...

Holopainen, J; Holopainen, Janne; Flynn, Chris

2004-01-01

273

Luminosities of Barred and Unbarred S0 Galaxies  

CERN Document Server

Lenticular galaxies with M_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 ~0.4 mag brighter than 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 E galaxy might be misclassified as an S0, or an S0 as an E. However, an E will never be misclassified an SB0, nor will an SB0 ever be called an E. This asymmetry is important because elliptical (E) galaxies are typically twice as luminous as lenticular (S0) ga...

Bergh, Sidney van den

2012-01-01

274

LHC Luminosity Upgrade Protecting Insertion Region Magnets from Collision Debris  

CERN Multimedia

The Large Hadron Collider built at CERN now enters a starting-up phase where the present design luminosity up to 1034 cm-2 s-1 will be reached after the running in phase. A possible upgrading of the machine to luminosity up to 10^35 cm^-2 s^-1 requires a new insertion region design, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion regions and in particular in the superconducting magnet coils with a possible risk of quench. We describe here how to protect the interaction region magnets against this irradiation to keep the energy deposition below critical values estimated for safe operation. The constraint is to keep the absorber size as small as possible to leave most of the magnet aperture available for the beam. This can be done by choosing a suitable material and design minimizing the load on the cryogenic system. Here we will describe design proposals for the phase I upgrade lay-out, i.e. luminosity up to 2.5 10^34 cm^-2 s^-1.

Wildner, E; Ferrari, A; Mauri, M; Mereghetti, A

2008-01-01

275

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

276

Effect of pyrene addition on the luminosity of methane flames  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses a study of enhancing the luminosity and hence the heat transfer from methane-air and methane-oxygen flames which is of importance in many processing applications. A kinetic analysis of soot formation by precursors addition shows that particle growth dominates oxidation for molecules larger than C{sub 16} scale hydrocarbons. For normal stoichiometric methane-air or methane-oxygen combustion, only one percent of the methane is converted to acetylene through pyrolysis and only 10% of the acetylene formed (0.1% of the initial methane) grows to particles size of pyrene. Preheating to 1,500 K can increase the production of acetylene and the molecular clusters of C{sub 16}H{sub 10} size to about 0.03%. However, by adding pyrene directly to the methane flame it is suggested that enhancement of soot generation and luminosity can be directly accomplished. The modeling of methane flames with pyrene addition is presented together with experimental verification of the predictions for soot and luminosity enhancement.

Fridman, A.A.; Nestor, S.A.; Saveiliev, A.V.; Zelepouga, S.A.; Kennedy, L.A.

1997-07-01

277

Studies of the high luminosity quasar, PDS 456  

CERN Document Server

X-ray and multi-wavelength observations of the most luminous known local (z<0.3) AGN, the recently discovered radio-quiet quasar PDS 456, are presented. The spectral energy distribution shows that PDS 456 has a bolometric luminosity of 1e47 erg/s, peaking in the UV. The X-ray spectrum obtained by ASCA and RXTE shows considerable complexity. The most striking feature observed is a deep, highly-ionised, iron K edge (8.7 keV, rest-frame), originating via reprocessing from highly ionised material, possibly the inner accretion disk. PDS 456 was found to be remarkably variable for its luminosity; in one flare the X-ray flux doubled in just about 15 ksec. If confirmed this would be an unprecedented event in a high-luminosity source, with a light-crossing time corresponding to about 2RS. The implications are that either flaring occurs within the very central regions, or else that PDS 456 is a super-Eddington or relativistically beamed system.

Reeves, J; Vaughan, S; Law-Green, D; Ward, M; Simpson, C; Pounds, K; Edelson, R

2000-01-01

278

Shapley Optical Survey. I: Luminosity Functions in the Supercluster Environment  

CERN Multimedia

We present the Shapley Optical Survey, a photometric study covering a 2 deg^2 region of the Shapley Supercluster core at z ~ 0.05 in two bands (B and R). The galaxy sample is complete to B=22.5 (>M^*+6, N_{gal}=16588), and R=22.0 (>M^*+7, N_{gal}=28008). The galaxy luminosity function cannot be described by a single Schechter function due to dips apparent at B ~ 17.5 (M_B ~ -19.3) and R ~ 17.0 (M_R ~ -19.8) and the clear upturn in the counts for galaxies fainter than B and R ~18 mag. We find, instead, that the sum of a Gaussian and a Schechter function, for bright and faint galaxies respectively, is a suitable representation of the data. We study the effects of the environment on the photometric properties of galaxies, deriving the galaxy luminosity functions in three regions selected according to the local galaxy density, and find a marked luminosity segregation, in the sense that the LF faint-end is different at more than 3sigma confidence level in regions with different densities. In addition, the luminosi...

Mercurio, A; Haines, C P; Gargiulo, A; Krusanova, N; Busarello, G; La Barbera, F; Capaccioli, M; Covone, G

2006-01-01

279

Modeling the red sequence: Hierarchical growth yet slow luminosity evolution  

CERN Multimedia

We explore the effects of mergers on the evolution of massive early-type galaxies by modeling the evolution of their stellar populations in a hierarchical context. We investigate how a realistic red sequence population set up by z~1 evolves under different assumptions for the merger and star formation histories, comparing changes in color, luminosity and mass. The purely passive fading of existing red sequence galaxies, with no further mergers or star formation, results in dramatic changes at the bright end of the luminosity function and color-magnitude relation. Without mergers there is too much evolution in luminosity at a fixed space density compared to observations. The change in color and magnitude at a fixed mass resemble that of a passively evolving population that formed relatively recently, at z~2. Mergers amongst the red sequence population ("dry mergers") occurring after z=1 build up mass, counteracting the fading of the existing stellar populations to give smaller changes in both color and luminos...

Skelton, Rosalind E; Somerville, Rachel S

2011-01-01

280

Order statistics of the early-type galaxy luminosity function  

CERN Multimedia

We apply order statistics (OS) to the bright end ($M_r < -22$) of the luminosity distribution of early-type galaxies spectroscopically identified in the SDSS DR7 catalog. We calculate the typical OS quantities of this distribution numerically, measuring the expectation value and variance of the $k^{th}$ most luminous galaxy in a sample with cardinality $N$ over a large ensemble of such samples. From these statistical quantities we explain why and in what limit the $k^{th}$ most luminous galaxies can be used as standard candles for cosmological studies. Since our sample contains all bright galaxies including the brightest cluster galaxies (BCG), based on OS we argue that BCGs can be considered as statistical extremes of a well-established Schechter luminosity distribution when galaxies are binned by redshift and not cluster-by-cluster. We presume that the reason behind this might be that luminous red ellipticals in galaxy clusters are \\em not random \\em samples of an overall luminosity distribution but bias...

Dobos, Laszlo

2011-01-01

 
 
 
 
281

Infrared Luminosity Functions of AKARI-SDSS Galaxies  

CERN Document Server

By cross-correlating AKARI infrared (IR) sources with the SDSS galaxies, we identified 2357 infrared galaxies with a spectroscopic redshift. This is not just one of the largest samples of local IR galaxies, but AKARI provides crucial FIR bands (9, 18, 65, 90, 140, and 160um) in accurately measuring galaxy SED across the peak of the dust emission at ~100um. By fitting modern IR SED models to the AKARI photometry, we measured the total infrared luminosity (L_IR) of individual galaxies more accurately. Using this L_IR, we constructed luminosity functions of infrared galaxies at a median redshift of z=0.031, with 4 times larger sample than previous work. The LF agrees well with that at z=0.0082 (RBGS), showing smooth and continuous evolution toward higher redshift LFs measured in the AKARI NEP deep field. The derived local cosmic IR luminosity density is Omega_IR=3.8x10^8 LsunMpc^-3. We separate galaxies into AGN, star-forming, and composite by using the [NII]/Ha vs [OIII]/Hb line ratios. The fraction of AGN show...

Goto, Tomotsugu; Malkan, Matthew; Takagi, Toshinobu; Inami, Hanae; Pearson, Chris; Wada, Takehiko; Matsuhara, Hideo; Yamauchi, Chisato; Takeuchi, Tsutomu T; Nakagawa, Takao; Oyabu, Shinki; Ishihara, Daisuke; Sanders, David B; Floc'h, Emeric Le; Lee, Hyung Mok; Jeong, Woong-Seob; Serjeant, Stephen; Sedgwick, Chris

2011-01-01

282

Total Infrared Luminosity Estimation of Resolved and Unresolved Galaxies  

CERN Multimedia

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

283

Factoring  

Science.gov (United States)

Test your factoring skills Factors and Multiples Jeopardy How much do you know about factoring and multiples? Play Jeopardy and find out! Prime Factoring Turkey Shoot Blast these turkeys using your factoring skills. Help the Professor Super save the planet by "cooking" the Giant Frozen Turkeys of Destruction. Math Lines 12 X-Factor Shoot the ball at the other factors to get a product of 12. You can also ...

Clark, Mr

2012-10-31

284

A composite plot of far-infrared versus radio luminosity, and the origin of far-infrared luminosity in quasars  

International Nuclear Information System (INIS)

We have constructed a composite plot of far-infrared versus radioluminosity for late-type galaxies, Seyferts, quasars and radio galaxies. The most striking result is that the radio and far-infrared luminosities of radio-quiet quasars are correlated and follow the same correlation as normal star-forming galaxies and ultra-luminous infrared galaxies, whereas the radio-loud quasars have luminosities in both bands similar to those of radio galaxies. We conclude that the far-infrared emission from radio-quiet quasars is from star-forming host galaxies and not from active galactic nuclei. The far-infrared radio plot may be a powerful discriminator between host galaxy type. (author)

1991-07-01

285

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

286

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

International Nuclear Information System (INIS)

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

2012-10-01

287

Evolution of the cluster X-ray luminosity function from the WARPS survey  

CERN Document Server

The evolution of the X-ray luminosity function of clusters of galaxies has been measured to z=0.85 using over 150 X-ray selected clusters found in the WARPS survey. We find no evidence for evolution of the luminosity function at any luminosity or redshift. The observations constrain the evolution of the space density of moderate luminosity clusters to be very small, and much less than predicted by most models of the growth of structure with Omega=1.

Jones, L R; Schärf, C A; Perlman, E S; Horner, D; Fairley, B; Wegner, G; Malkan, M A

2000-01-01

288

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

International Nuclear Information System (INIS)

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

1993-01-01

289

The VIMOS VLT Deep Survey. Evolution of the luminosity functions by galaxy type up to z = 1.5 from first epoch data  

Science.gov (United States)

From first epoch observations of the VIMOS VLT Deep Survey (VVDS) we have derived luminosity functions for galaxy samples selected by spectral type out to z=1.5. With the VVDS we are able to investigate within the same sample the evolution of the type dependent luminosity function selected in several rest-frame bands over 70% of the age of the Universe. The simple I_AB=24 VVDS magnitude limit is significantly fainter than other complete spectroscopic surveys and allows the determination of the faint end slope of the luminosity function with unprecedented accuracy. Galaxies have been classified in four spectral types, from early type to irregular galaxies, using their colours and redshift. Luminosity functions have been computed in the U, B, V, R and I rest frame bands for each type, in redshift bins from z=0.05 to z=1.5. In all the considered rest frame bands, we find a significant steepening of the luminosity function from early to late types. The characteristic luminosity M* of the Schechter function is significantly fainter for late type galaxies and this difference between types increases in the redder bands. For each spectral type we find a brightening of M* with increasing redshift, ranging from ?0.5 mag for early type galaxies to ~1 mag for the latest type galaxies, while the slope of the luminosity function of each spectral type is consistent with being redshift-independent. The luminosity function of early type galaxies is consistent with passive evolution up to z˜ 1.1, whilst the number of bright (MB_AB< -20) early type galaxies has decreased by ~40% from z˜ 0.3 to z ˜ 1.1. The normalisation of the luminosity function of latest type galaxies evolves strongly with redshift with an increase of more than a factor 2 from z˜ 0.3 to z˜ 1.3: the density of bright (MB_AB< -20) late type galaxies in the same redshift range increases of a factor ~6.6. These results indicate a strong type-dependent evolution and identifies the latest spectral types as responsible for most of the evolution of the UV-optical luminosity function out to z=1.5.

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

2006-09-01

290

Testing 24 micron and Infrared Luminosity as Star Formation Tracers for Galactic Star Forming Regions  

CERN Multimedia

We have tested some relations for star formation rates used in extra-galactic studies for regions within the Galaxy. In nearby molecular clouds, where the IMF is not fully-sampled, the dust emission at 24 micron greatly underestimates star formation rates (by a factor of 100 on average) when compared to star formation rates determined from counting YSOs. The total infrared emission does no better. In contrast, the total far-infrared method agrees within a factor of 2 on average with star formation rates based on radio continuum emission for massive, dense clumps that are forming enough massive stars to have the total infrared luminosity exceed 10^4.5 Lsun. The total infrared and 24 micron also agree well with each other for both nearby, low-mass star forming regions and the massive, dense clumps regions.

Vutisalchavakul, Nalin

2013-01-01

291

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

CERN Multimedia

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

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

2009-01-01

292

Upgraded Readout Electronics for the ATLAS Liquid Argon Calorimeters at the High Luminosity LHC  

CERN Document Server

The ATLAS Liquid Argon (LAr) calorimeters produce a total of 182,486 signals which are digitized and processed by the front-end and back-end electronics at every triggered event. In addition, the front-end electronics is summing analog signals to provide coarsely grained energy sums, called trigger towers, to the first-level trigger system, which is optimized for nominal LHC luminosities. However, the pile-up noise expected during the High Luminosity phases of LHC will be increased by factors of 3 to 7. An improved spatial granularity of the trigger primitives is therefore proposed in order to improve the identification performance for trigger signatures, like electrons or photons, at high background ejection rates. For the first upgrade phase cite{pahse1loi} in 2018, new LAr Trigger Digitizer Boards (LTDB) are being designed to receive higher granularity signals, digitize them on detector and send them via fast optical links to a new digital processing system (DPS). The DPS applies a digital filtering and id...

Andeen, T; The ATLAS collaboration

2012-01-01

293

Upgraded readout electronics for the ATLAS LAr Calorimeter at the High Luminosity LHC  

CERN Document Server

The ATLAS Liquid Argon (LAr) calorimeters produce a total of 182,486 signals which are digitized and processed by the front-end and back-end electronics at every triggered event. In addition, the front-end electronics is summing analog signals to provide coarsely grained energy sums, called trigger towers, to the first-level trigger system, which is optimized for nominal LHC luminosities. However, the pile-up noise expected during the High Luminosity phases of LHC will be increased by factors of 3 to 7. An improved spatial granularity of the trigger primitives is therefore proposed in order to improve the identification performance for trigger signatures, like electrons or photons, at high background ejection rates. For the first upgrade phase [1] in 2018, new digital tower builder boards (sTBB) are being designed to receive higher granularity signals, digitize them on detector and send them via fast optical links to a new digital processing system (DPS). The DPS applies a digital filtering and identifies sig...

Andeen, T; The ATLAS collaboration

2012-01-01

294

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

CERN Multimedia

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

295

Radiative Transfer Modeling of Lyman Alpha Emitters: I. Statistics of Spectra and Luminosity  

CERN Document Server

We combine a cosmological reionization simulation with box size of 100Mpc/h on a side and a Monte Carlo Lyman-alpha (Lya) radiative transfer code to model Lyman Alpha Emitters (LAEs) at z~5.7. The model introduces Lya radiative transfer as the single factor for transforming the intrinsic Lya emission properties into the observed ones. Spatial diffusion of Lya photons from radiative transfer results in extended Lya emission and only the central part with high surface brightness can be observed. Because of radiative transfer, the appearance of LAEs depends on density and velocity structures in circumgalactic and intergalactic media as well as the viewing angle, which leads to a broad distribution of apparent (observed) Lya luminosity for a given intrinsic Lya luminosity. Radiative transfer also causes frequency diffusion of Lya photons. The resultant Lya line is asymmetric with a red tail. The peak of the Lya line shifts towards longer wavelength and the shift is anti-correlated with the apparent to intrinsic L...

Zheng, Zheng; Trac, Hy; Miralda-Escude, Jordi

2009-01-01

296

GRB 120422A: A Low-luminosity Gamma-ray Burst Driven by Central Engine  

CERN Multimedia

GRB 120422A is a low-luminosity Gamma-ray burst (GRB) associated with a bright supernova, which distinguishes itself by its relatively short T90 ~ 5 s and an energetic X-ray tail. We analyze the Swift BAT and XRT data and discuss the physical implications. We show that the early steep decline in the X-ray light curve can be interpreted as the curvature tail of a late emission episode around 58-86 s, with a curved instantaneous spectrum at the end of the emission episode. Together with the main activity in the first ~ 20 s and the weak emission from 40 s to 60 s, the prompt emission is variable, which points towards a central engine origin, in contrast to the shock breakout origin as invoked to interpret some other nearby low-luminosity supernova GRBs. The curvature effect interpretation and interpreting the early shallow decay as the coasting external forward shock emission in a wind medium both give a constraint on the bulk Lorentz factor \\Gamma to be around several. Comparing the properties of GRB 120422A a...

Zhang, Bin-Bin; Shen, Rong-Feng; Xu, Dong; Zhang, Fu-Wen; Wei, Da-Ming; Burrows, David N; Zhang, Bing

2012-01-01

297

Photometric Properties and Luminosity Function of Nearby Massive Early-type Galaxies  

Science.gov (United States)

We perform photometric analyses of a bright early-type galaxy sample with 2949 galaxies (Mr 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 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 * ~ 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 massive galaxies between observations and predictions of the hierarchical structure formation model.

He, Y. Q.; Xia, X. Y.; Hao, C. N.; Jing, Y. P.; Mao, S.; Li, Cheng

2013-08-01

298

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1983-02-01

299

High Luminosity Large Hadron Collider A description for the European Strategy Preparatory Group  

CERN Document Server

The Large Hadron Collider (LHC) is the largest scientific instrument ever built. It has been exploring the new energy frontier since 2009, gathering a global user community of 7,000 scientists. It will remain the most powerful accelerator in the world for at least two decades, and its full exploitation is the highest priority in the European Strategy for Particle Physics, adopted by the CERN Council and integrated into the ESFRI Roadmap. To extend its discovery potential, the LHC will need a major upgrade around 2020 to increase its luminosity (rate of collisions) by a factor of 10 beyond its design value. As a highly complex and optimized machine, such an upgrade of the LHC must be carefully studied and requires about 10 years to implement. The novel machine configuration, called High Luminosity LHC (HL-LHC), will rely on a number of key innovative technologies, representing exceptional technological challenges, such as cutting-edge 13 tesla superconducting magnets, very compact and ultra-precise superconduc...

Rossi, L

2012-01-01

300

Spectrophotometric monitoring of high luminosity active galactic nuclei. Pt. 1  

International Nuclear Information System (INIS)

[en] We report on a spectrophotometric monitoring programme of high luminosity active galactic nuclei (AGN) using the 2.5-m Issac Newton telescope. Data acquisition and analysis are explained, with emphasis on the care to be taken when comparing data from different epochs. The data are presented for individual objects. A comparison of the L?, CIV and CIII profiles shows that, contrary to what has previously been supposed, the profiles of different lines in a single object are not always the same as each other. (author)

1989-07-01

 
 
 
 
301

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

2013-01-01

302

The luminosity monitor of the HERMES experiment at DESY  

CERN Multimedia

A detector is described which measures the luminosity of the HERMES experiment at DESY. It is based on the coincident detection of electron-positron and photon pairs, or electron pairs, originating from the interaction of the beam positrons, or electrons, with the electrons of the atomic gas target. It consists of two calorimeters with radiation hard NaBi(WO sub 4) sub 2 crystals. Properties of the monitor, investigated in an electron test beam, and its performance in the experiment are presented.

Benisch, T; Devitsin, E G; Kozlov, V; Potashov, S Yu; Rith, K; Terkulov, A R; Weiskopf, C

2001-01-01

303

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.

1995-01-01

304

APD performance in a luminosity monitor at LEP  

CERN Document Server

Avalanche photo-diodes (APDs) are being used as optical readout elements in a sampling electromagnetic calorimeter made of alternate layers of tungsten and plastic scintillators. The calorimeter serves as a small-angle luminosity monitor in the stray magnetic field of the ALEPH detector at LEP (CERN). Its scintillators are coupled both to APDs and conventional PMTs simultaneously via wavelength shifter fibres. In this paper we present results on the overall performance of the APDs, including gain and stability versus time and energy, based on the direct comparison of the two photosensitive devices. (6 refs).

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

2000-01-01

305

The radio luminosity distribution of pulsars in 47 Tucanae  

CERN Document Server

We have used the Australia Telescope Compact Array to seek the integrated radio flux from all the pulsars in the core of the globular cluster 47 Tucanae. We have detected an extended region of radio emission and have calibrated its flux against the flux distribution of the known pulsars in the cluster. We find the total 20-cm radio flux from the cluster's pulsars to be S = 2.0 +/- 0.3 mJy. This implies the lower limit to the radio luminosity distribution to be L_1400 = 0.4 mJy kpc^2 and the size of the observable pulsar population to be N < 30.

McConnell, D; Connors, T; Ables, J G

2004-01-01

306

APD performance in a luminosity monitor at LEP  

International Nuclear Information System (INIS)

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

2000-03-11

307

NGC4258 a jet-dominated low-luminosity AGN?  

CERN Multimedia

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

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

2002-01-01

308

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

309

The GRB luminosity function: prediction of the internal shock model and comparison to observations  

International Nuclear Information System (INIS)

We compute the expected GRB luminosity function in the internal shock model. We find that if the population of GRB central engines produces all kind of relativistic outflows, from very smooth to highly variable, the luminosity function has to branchs: at low luminosity, the distribution is dominated by low efficiency GRBs and is close to a power law of slope -0.5, whereas at high luminosity, the luminosity function follows the distribution of injected kinetic power. Using Monte Carlo simulations and several observational constrains (BATSE logN-logP diagram, peak energy distribution of bright BATSE bursts, fraction of XRFs in the HETE2 sample), we show that it is currently impossible to distinguish between a single power law or a broken power law luminosity function. However, when the second case is considered, the low-luminosity slope is found to be -0.6±0.2, which is compatible with the prediction of the internal shock model.

2008-05-22

310

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

CERN Document Server

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; Pogge, Richard W; Vestergaard, Marianne

2008-01-01

311

The Planetary Nebula Luminosity Function: Pieces of the Puzzle  

CERN Document Server

Extragalactic surveys in the emission line of [O III] 5007 have provided us with the absolute line strengths of large, homogeneous sets of planetary nebulae. These data have been used to address a host of problems, from the measurement of the extragalactic distance scale, to the study of stellar populations. I review our current understanding of the [O III] planetary nebula luminosity function (PNLF), and discuss some of the physical processes that effect its structure. I also describe the features of the H-alpha PNLF, a function that, upon first glance, looks similar to the [O III] PNLF, but which includes a very different set of objects. Finally, I discuss recent measurements of alpha, the number of PNe found in a stellar population, normalized to that population's bolometric luminosity. I show that, contrary to expectations, the values of alpha found in actively star-forming spirals is essentially the same as those measured in late-type elliptical and lenticular systems. I discuss how this result sheds lig...

Ciardullo, Robin

2009-01-01

312

A Search for Low-Luminosity BL Lacertae Objects  

CERN Multimedia

Many properties of BL Lacs have become explicable in terms of the "relativistic beaming" hypothesis whereby BL Lacs are FR-1 radio galaxies viewed nearly along the jet axis. However, a possible problem with this model is that a transition population between beamed BL Lacs and unbeamed FR-1s has not been detected. A transition population of "low-luminosity BL Lacs" was predicted to exist in abundance in X-ray-selected samples such as the Einstein Extended Medium Sensitivity Survey (EMSS) by Browne & Marcha. However, these BL Lacs may have been misidentified as clusters of galaxies. We have conducted a search for such objects in the EMSS with the ROSAT HRI; and here we present ROSAT HRI images, optical spectra and VLA radio maps for a small number of BL Lacs which were previously misidentified in the EMSS catalog as clusters of galaxies. While these objects are slightly lower in luminosity than other EMSS BL Lacs, their properties are too similar to the other BL Lacs in the EMSS sample to "bridge the gap" b...

Rector, T A; Perlman, E S; Rector, Travis A.; Stocke, John T.; Perlman, Eric S.

1999-01-01

313

Absolute luminosity measurements with the LHCb detector at the LHC  

CERN Document Server

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

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

2012-01-01

314

The z=5 Quasar Luminosity Function from SDSS Stripe 82  

CERN Multimedia

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

315

The intrinsic luminosity and initial period of pulsars  

Energy Technology Data Exchange (ETDEWEB)

The observed properties of pulsars are modeled on the assumption that they evolve by emitting magnetic dipole radiation and have exponentially decaying magnetic fields. The models are constructed by using Monte Carlo techniques to generate a Galactic sample of pulsars having particular distributions of initial periods, magnetic dipole moments, and positions. By choosing a relationship between the radio luminosity L(r), the period (P), and the P derivative, it is determined which pulsars of the generated sample could be detected by one of the major pulsar surveys. Detailed account is taken of known selection effects in these surveys. Models in which the size of the pulsar emission cone is dependent on the period are considered. The properties of the detectable pulsars are compared with the properties of the observed pulsars, and the initial distributions and luminosity relation of the model are adjusted until a satisfactory agreement is obtained. A crucial point is that the observed relation between L(r) and P, P derivative is affected by selection effects and does not apply to the actual pulsar population. It is found that the best fits are obtained with models in which the pulsars are injected with relatively long periods, about 0.5 sec. 27 refs.

Emmering, R.T.; Chevalier, R.A. (Virginia Univ., Charlottesville (USA))

1989-10-01

316

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

317

An upgraded ATLAS Central Trigger for 2015 LHC luminosities  

CERN Multimedia

The LHC collides protons at a rate of 40 MHz and each collision produces $\\sim$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 $\\sim$75 kHz with a decision latency of $\\sim$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. I...

Ohm, C; The ATLAS collaboration

2013-01-01

318

An upgraded ATLAS Central Trigger for post-2014 LHC luminosities  

CERN Multimedia

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

319

A luminosity monitor for LHC [notes of a thesis  

CERN Multimedia

LHC luminosity will reach 10/sup 34/ cm/sup -2/ s/sup -1/ but special runs at 10/sup 28/ cm/sup -2/ s/sup -1/ are foreseen. Thus a luminosity monitor must have a dynamic range of six orders of magnitude. A good tolerance to radiation is also required. A detector using both ionisation and secondary emission techniques has been studied in this context. Its design is based on monitors used previously at the CERN PS and SPS. Special attention was devoted to minimise leakage currents. Linearity in both Secondary Emission Counter (SEC) and Ionisation Chamber (IC) modes has been tested from ~10/sup 4/ incident particles to ~10/sup 8/ incident particles. SEC is linear above ~5.10/sup 6/ incident particles while IC is linear over the full studied range. However, because of the radiation environment at LHC, the SEC mode is much preferred at high intensity. A solution actually foreseen is to switch from IC to SEC mode when the intensity is around 5.10/sup 6/ incident particles per second corresponding to an LHC luminosi...

Perrot, Anne Laure

2000-01-01

320

The faint end of the galaxy luminosity function  

CERN Document Server

We present and discuss optical measurements of the faint end of the galaxy luminosity function down to M_R = -10 in five different local environments of varying galaxy density and morphological content. The environments we studied, in order of decreasing galaxy density, are the Virgo Cluster, the NGC 1407 Group, the Coma I Group, the Leo Group and the NGC 1023 Group. Our results come from a deep wide-angle survey with the NAOJ Subaru 8 m Telescope on Mauna Kea and are sensitive down to very faint surface-brightness levels. Galaxies were identified as group or cluster members on the basis of their surface brightness and morphology. The faintest galaxies in our sample have R ~ 22.5. There were thousands of fainter galaxies but we cannot distinguish cluster members from background galaxies at these faint limits so do not attempt to determine a luminosity function fainter than M_R = -10. In all cases, there are far fewer dwarfs than the numbers of low mass halos anticipated by cold dark matter theory. The mean lo...

Trentham, N; Trentham, Neil

2002-01-01

 
 
 
 
321

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

322

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

323

HII Region Luminosity Function of the Interacting Galaxy M51  

CERN Document Server

We present a study of HII regions in M51 using the Hubble Space Telescope ACS images taken as part of the Hubble Heritage Program. We have catalogued about 19,600 HII regions in M51 with Ha luminosity in the range of L = 10^{35.5} erg/s to 10^{39.0} erg/s. The Ha luminosity function of HII regions (HII LF) in M51 is well represented by a double power law with its index alpha=-2.25\\pm0.02 for the bright part and alpha=-1.42\\pm0.01 for the faint part, separated at a break point L= 10^{37.1} erg/s. This break was not found in previous studies of M51 HII regions. Comparison with simulated HII LFs suggests that this break is caused by the transition of HII region ionizing sources, from low mass clusters (with ~ 10^3 M_sun, including several OB stars) to more massive clusters (including several tens of OB stars). The HII LFs with L < 10^{37.1} erg/s are found to have different slopes for different parts in M51: the HII LF for the interarm region is steeper than those for the arm and the nuclear regions. This obs...

Lee, Jong Hwan; Lee, Myung Gyoon

2011-01-01

324

Factoring  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Factoring, finding a non-trivial factorization of a composite positive integer, is believed to be a hard problem. How hard we think it is, however, changes almost on a daily basis. Predicting how hard factoring will be in the future, an important issue for cryptographic applications of composite num...

Lenstra, Arjen K.

325

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.

1990-01-01

326

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

327

Deriving an X-ray luminosity function of dwarf novae based on parallax measurements  

CERN Multimedia

We have derived an X-ray luminosity function using parallax-based distance measurements of a set of 12 dwarf novae, consisting of Suzaku, XMM-Newton and ASCA observations. The shape of the X-ray luminosity function obtained is the most accurate to date, and the luminosities of our sample are concentrated between ~10^{30}-10^{31} erg s^{-1}, lower than previous measurements of X-ray luminosity functions of dwarf novae. Based on the integrated X-ray luminosity function, the sample becomes more incomplete below ~3 x 10^{30} erg s^{-1} than it is above this luminosity limit, and the sample is dominated by X-ray bright dwarf novae. The total integrated luminosity within a radius of 200 pc is 1.48 x 10^{32} erg s^{-1} over the luminosity range of 1 x 10^{28} erg s^{-1} and the maximum luminosity of the sample (1.50 x 10^{32} erg s^{-1}). The total absolute lower limit for the normalised luminosity per solar mass is 1.81 x 10^{26} erg s^{-1} M^{-1}_{solar} which accounts for ~16 per cent of the total X-ray emissivit...

Byckling, Kristiina; Thorstensen, John; Osborne, Julian

2010-01-01

328

High luminosity IRAS galaxies - I. The proportion of IRAS galaxies in interacting systems  

International Nuclear Information System (INIS)

[en] We report CCD imaging of a complete sample of 60 high-luminosity IRAS galaxies and of a control sample of 87 optically selected galaxies. The galaxies have been grouped in seven classes depending on the presence or absence of faint or bright, nearby or distant, companions, and signs of interaction or mergers such as tidal arms or disturbed structure. We find that 18±5 per cent of optically selected galaxies are in interacting or merging systems. The excess of interacting pairs over those which we would expect to find by chance is about 30 per cent. Many of the pairs are unresolved by the IRAS beam, but we demonstrate that this cannot explain the enhanced fraction of pairs. These results indicate that galaxy interaction is a common causal factor in luminous IR activity. (author)

1989-09-15

329

Observational evidence for a correlation between peak-luminosities and beaming in GRBs  

CERN Multimedia

We calculate the unseen-but-true GRB-event rate from a current flux-limited sample of 33 GRBs with individually measured redshifts. We consider a GRB-event rate which is proportional to the star-formation rate, in view of the GRB-SNe association in SN1998bw and GRB030329. By fitting a log-normal distribution of GRB peak-luminosities, we find a ratio of about 450 for the true-to-observed GRB-event rates. This provides an independent derivation of the GRB-beaming factor of about 500 obtained by Frail et al. (2001) from sources with standard GRB-energies. We discuss applications to GRB980425.

Van Putten, M H P M; Putten, Maurice H.P.M. van; Regimbau, Tania

2003-01-01

330

Tolman's Luminosity-Distance, Poincare's Light-Distance and Cayley-Klein's Hyperbolic Distance  

CERN Document Server

We deduce Tolman's formula of luminosity-distance in Cosmology from Poincare's definition of light-distance with Lorentz Transformation (LT).In Minkowskian metric, if distance is proper time (as it is often argued) then light-distance must be also the shortest distance, like proper duration (unlike Einstein's longest length within rest system). By introducing Poincare's proper light-distance in Einstein's basic synchronization we deduce a dilated distance between observer and receding mirror (with relativistic Doppler factor). Such a distance corresponds not to an Euclidean distance (Einstein's rigid rod) but to an Hyperbolic distance (Cayley-Klein) with a Lobatchevskian Horizon. From a basic proportionality hyperbolic distance-velocity, we deduce the law of Hubble. By following Penrose's Lobatchevskian representation of LT, we transform Special Relativity (SR) into an Hyperbolic Cosmological Relativity (HCR). by using only the LT but the whole LT. In Hyperbolic Rotation motion (basic active LT or Einstein's ...

Pierseaux, Yves

2009-01-01

331

A low luminosity state in the massive X-ray binary SAX J0635+0533  

Science.gov (United States)

The X-ray pulsar SAX J0635+0533 was repeatedly observed with the XMM-Newton satellite in 2003-2004. The precise localization provided by these observations confirms the association of SAX J0635+0533 with a Be star. The source was found, for the first time, in a low-intensity state, a factor ~30 lower than that seen in all previous observations. The spectrum, well fitted by an absorbed power law with photon index ~1.7 and NH = 1.2×1022 cm-2, was compatible with that of the high state. The low flux did not allow the detection of the pulsations at 33.8 ms seen in BeppoSAX and RXTE data. In view of the low luminosity observed in 2003-2004, we reconsider the peculiarities of this source in both the accretion and rotation-powered scenarios.

Mereghetti, S.; La Palombara, N.

2009-09-01

332

A low luminosity state in the massive X-ray binary SAX J0635+0533  

CERN Multimedia

The X-ray pulsar SAX J0635+0533 was repeatedly observed with the XMM-Newton satellite in 2003-2004. The precise localization provided by these observations confirms the association of SAX J0635+0533 with a Be star. The source was found, for the first time, in a low intensity state, a factor ~30 lower than that seen in all previous observations. The spectrum, well fitted by an absorbed power law with photon index ~1.7 and N_H = 1.2x10^22 cm^-2, was compatible with that of the high state. The low flux did not allow the detection of the pulsations at 33.8 ms seen BeppoSAX and RXTE data. In view of the small luminosity observed in 2003-2004, we reconsider the peculiarities of this source in both the accretion and rotation powered scenarios.

Mereghetti, Sandro

2009-01-01

333

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; Daiana Boijink; Ronise Ferreira; Márcia Helena Wagner; Fernando Branco Barletta

2010-01-01

334

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.

1979-01-01

335

CdTe Photoconductors for LHC Luminosity Monitoring  

CERN Multimedia

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

336

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

CERN Multimedia

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

Barkana, Rennan

2013-01-01

337

Distances, luminosities, and temperatures of the coldest known substellar objects.  

UK PubMed Central (United Kingdom)

The coolest known brown dwarfs are our best analogs to extrasolar gas-giant planets. The prolific detections of such cold substellar objects in the past 2 years have spurred intensive follow-up, but the lack of accurate distances is a key gap in our understanding. We present a large sample of precise distances based on homogeneous mid-infrared astrometry that robustly establishes absolute fluxes, luminosities, and temperatures. The coolest brown dwarfs have temperatures of 400 to 450 kelvin and masses almost equal to 5 to 20 times that of Jupiter, showing they bridge the gap between hotter brown dwarfs and gas-giant planets. At these extremes, spectral energy distributions no longer follow a simple correspondence with temperature, suggesting an increasing role of other physical parameters, such as surface gravity, vertical mixing, clouds, and metallicity.

Dupuy TJ; Kraus AL

2013-09-01

338

Galaxy evolution as a function of environment and luminosity  

CERN Document Server

We present an analysis of star formation and nuclear activity of about 28000 galaxies in a volume-limited sample taken from SDSS DR4 low-redshift catalogue (LRC) taken from the New York University Value Added Galaxy Catalogue (NYU-VAGC) of Blanton et al. 2005, with 0.005~ L*) galaxies. Moreover the fraction of galaxies with the optical signatures of an active galactic nucleus (AGN) decreases steadily from ~50\\% at Mr~-21 to ~0 per cent by Mr~-18 closely mirroring the luminosity dependence of the passive galaxy fraction in low-density environments (see fig. 1 continuous lines). This result reflects the increasing importance of AGN feedback with galaxy mass for their evolution, such that the star formation histories of massive galaxies are primarily determined by their past merger history.

Mercurio, A; Gargiulo, A; La Barbera, F; Merluzzi, P; Busarello, G

2010-01-01

339

Distances, Luminosities, and Temperatures of the Coldest Known Substellar Objects  

CERN Multimedia

The coolest known brown dwarfs are our best analogs to extrasolar gas-giant planets. The prolific detections of such cold substellar objects in the past two years has spurred intensive followup, but the lack of accurate distances is a key gap in our understanding. We present a large sample of precise distances based on homogeneous mid-infrared astrometry that robustly establish absolute fluxes, luminosities, and temperatures. The coolest brown dwarfs have temperatures of 400-450 K and masses ~5-20 times that of Jupiter, showing they bridge the gap between hotter brown dwarfs and gas-giant planets. At these extremes, spectral energy distributions no longer follow a simple correspondence with temperature, suggesting an increasing role of other physical parameters such as surface gravity, vertical mixing, clouds, and metallicity.

Dupuy, Trent J

2013-01-01

340

CMS HCAL Endcap Simulations for the High Luminosity LHC  

Science.gov (United States)

The long-term high luminosity upgrade to the LHC will increase the levels of radiation affecting the CMS calorimeters. By the end of Phase 2, parts of the electromagnetic and hadronic endcap calorimeters could receive up to 10 MRad of radiation. A model of the radiation damage to HCAL, which has been implemented in the CMS fast simulation, will be described. The effects of radiation on physics capabilities with jets will be presented, with the most important effect coming from scaling of photodetector noise due to recalibration. In addition, a standalone Geant4 simulation with a simplified geometry can be used to test configurations with new radiation-hard ECALs. Results for pion response and resolution with new configurations will be shown.

Pedro, Kevin

2013-04-01

 
 
 
 
341

Shapley Optical Survey - I. Luminosity functions in the supercluster environment  

Science.gov (United States)

We present the Shapley Optical Survey, a photometric study covering a ~2-deg2 region of the Shapley supercluster core at z~ 0.05 in two bands (B and R). The galaxy sample is complete to B= 22.5 (>M*+ 6, Ngal= 16588) and R= 22.0 (>M*+ 7, Ngal= 28008). The galaxy luminosity function (LF) cannot be described by a single Schechter function due to dips apparent at B~ 17.5 (MB~-19.3) and R~ 17.0 (MR~-19.8) and the clear upturn in the counts for galaxies fainter than B and R~ 18mag. We find, instead, that the sum of a Gaussian and a Schechter function, for bright and faint galaxies, respectively, is a suitable representation of the data. We study the effects of the environment on the photometric properties of galaxies, deriving the galaxy LFs in three regions selected according to the local galaxy density, and find a marked luminosity segregation, in the sense that the LF faint end is different at more than 3? confidence level in regions with different densities. In addition, the LFs of red and blue galaxy populations show very different behaviours: while red sequence counts are very similar to those obtained for the global galaxy population, the blue galaxy LFs are well described by a single Schechter function and do not vary with the density. Such large environmentally dependent deviations from a single Schechter function are difficult to produce solely within galaxy merging or suffocation scenarios. Instead the data support the idea that mechanisms related to the cluster environment, such as galaxy harassment or ram-pressure stripping, shape the galaxy LFs by terminating star formation and producing mass-loss in galaxies at ~M*+ 2, a magnitude range where blue late-type spirals used to dominate cluster populations, but are now absent.

Mercurio, A.; Merluzzi, P.; Haines, C. P.; Gargiulo, A.; Krusanova, N.; Busarello, G.; Barbera, F. La; Capaccioli, M.; Covone, G.

2006-05-01

342

D0 luminosity monitor constant for the 1994-1996 Tevatron run  

Energy Technology Data Exchange (ETDEWEB)

The D0 experiment calculates its luminosity using the visible cross section (luminosity monitor constant) {sigma}{sub L0} for its Level 0 trigger based on the world average {anti p}p inelastic cross sections at {radical}s - 1.8 TeV. For the 1992-1993 Tevatron Run (1A), the luminosity monitor constant was determined to be {sigma}{sub L0} = 46. 7{+-}2.5 mb. For the 1994-1996 Tevatron Run (1B/1C), the luminosity monitor constant changed slightly with an upgrade to the electronics in the Level 0 trigger. The luminosity monitor constant becomes on average {sigma}{sub L0} - 44.53 {+-} 2.37 mb for Run 1B/1C. In addition, small corrections for halo and multiple single diffraction are included in integrated luminosity determinations.

Bantly, J., Krane, J., Owen, D., Partridge, R., Paterno, L.

1997-06-01

343

Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey  

CERN Multimedia

Extreme value statistics (EVS) is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey (SDSS). We analyze the DR8 Main Galaxy Sample (MGS), divided into red and blue subsamples, as well as the Luminous Red Galaxies (LRG). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index $\\xi$, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high luminosity end. Assuming, however, $\\xi=0$, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided uncertainties arising both from the finite batch size and from the batch size distribution are accounted for. For a volume limited sample of LRGs, results show th...

Taghizadeh-Popp, M; Racz, Z; Regoes, E; Szalay, A S

2012-01-01

344

Halo Model at Its Best: Constraints on Conditional Luminosity Functions from Measured Galaxy Statistics  

CERN Document Server

(Summary) Using the conditional luminosity function (CLF) -- the luminosity distribution of galaxies in a dark matter halo -- as the fundamental building block, we present an empirical model for the galaxy distribution. The model predictions are compared with the published luminosity function and clustering statistics from Sloan Digital Sky Survey (SDSS) at low redshifts, and galaxy correlation functions from COMBO-17 survey at a redshift of 0.6, DEEP2 survey at a redshift of unity, and Great Observatories Deep Origins Survey (GOODS) at a redshift around 3. The comparison with statistical measurements allows us to constrain certain parameters related to analytical descriptions that describe the relation between a dark matter halo and its central galaxy luminosity, its satellite galaxy luminosity, and the fraction of early- and late-type galaxies of that halo. The single parameter best constrained by clustering measurements is the total satellite galaxy luminosity averaged over the halo mass distribution probe...

Cooray, A R

2006-01-01

345

The D0 luminosity monitor constant for ? s = 630 GeV  

International Nuclear Information System (INIS)

D0 has calculated the luminosity monitor constant for ?s= 630 GeV. The inelastic p anti p cross section was interpolated between measurements performed at ?s = 546 and 1800 GeV. The geometric acceptance, hardware efficiency, and luminosity-dependent corrections are similar to those previously published for the full Tevatron energy. We find a luminosity-weighted value of ?L0 = 34.04 ± 1.05 mb, yielding a precision of ± 3.08%

1997-01-01

346

Factorize  

Science.gov (United States)

This interactive Java applet helps students explore the relationship between area and multiplication. First, users are asked to input all factor pairs of a given number. Then, selecting each of those factor pairs, the user draws the respective rectangular array by clicking and dragging across a grid. Options include the use of the commutative property (e.g., user must enter both 2x4 and 4x2 for factors of 8 and represent them with different arrays), entering a number of the user's own choice, and an optional scoring feature allowing the user to keep track of the number correct.

2004-01-01

347

Factors  

Science.gov (United States)

This lesson is designed to develop students' abilities to find factors of whole numbers. The lesson also introduces prime numbers. This lesson provides links to discussions and activities related to factors as well as suggested ways to integrate them into the lesson. Finally, the lesson provides links to follow-up lessons designed for use in succession with the current one. Note, reading level is not indicated because the lesson does not include student reading material.

2010-01-01

348

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

349

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

International Nuclear Information System (INIS)

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

2012-01-01

350

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

351

Challenges on the high luminosity frontier of e+ e-  

International Nuclear Information System (INIS)

[en] 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

1993-01-01

352

Calibration of Gamma-Ray Burst Luminosity Indicators  

CERN Multimedia

Several gamma-ray burst (GRB) luminosity indicators (LIs)have been proposed. Unlike SNe Ia, calibration of GRB LIs using a low-redshift sample is difficult. Based on the Bayesian theory, here we propose an approach to calibrate these LIs without introducing a low-redshift GRB sample. The essential points of our approach include, (1) calibrate the power-law indices in the LIs with a sample of GRBs in a narrow redshift range (Delta z); and (2) marginalize the coefficient of the LIs over a reasonable range of cosmological parameters. We take our newly discovered multivariable GRB LIs as an example and test the validity of our approach through simulations. We show that while the coefficient strongly depends on the cosmological parameters, the power-law indices do not as long as Delta z is small enough. The selection of Delta z for a particular GRB sample could be judged according to the size and the observational uncertainty of the sample. There is no preferable redshift to perform the calibration of the indices,...

Liang, E; Liang, Enwei; Zhang, Bing

2005-01-01

353

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

CERN Multimedia

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

354

The z=3 QSO Luminosity Function with SWIRE  

CERN Multimedia

We use a simple optical/infrared photometric selection of high redshift QSOs which identifies a Lyman Break in the optical and requires a red IRAC color to distinguish QSOs from common interlopers. We find 100 U-dropout (z=3) QSO candidates with r'<22 within 11.2 deg^2 in the ELAIS-N1 & ELAIS-N2 fields in the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Legacy Survey. Spectroscopy of 10 candidates shows that they are all QSOs with 2.83luminosity function is two magnitudes fainter than SDSS and, when combined with those data, gives a faint end slop \\beta = 1.62 \\pm 0.18, consistent with measurements at z<2 and steeper than initial measurements at the same redshift.

Siana, B; Smith, H E; Lonsdale, C J; Gonzalez-Solares, E; Farrah, D; Babbedge, T S R; Rowan-Robinson, M; Surace, J; Shupe, D; Fang, F

2006-01-01

355

The Fast Tracker Architecture for the LHC baseline luminosity  

CERN Multimedia

Hadron collider experiments search for extremely rare processes hidden in much higher background levels. Only a tiny fraction of the produced collisions can be stored on tape and an enormous real-time data reduction is needed. This requires massive computing power to minimize the on-line execution time of complex algorithms. A multi-level trigger is an effective solution for an otherwise impossible problem. The Fast Tracker (FTK) [1, 2] has been proposed for high quality track finding at very high rates (Level-1 output rates) for the ATLAS experiment. FTK will use FPGA and ASIC devices in order to complement CPUs. FTK beats the combinatorial challenge with special associative memories, where parallelism is exploited to the maximum level. The associative memories compare the track detector hits to all pre-calculated track patterns at once. The system design is defined and proposed for high-luminosity studies including low-PT Bphysics and high-PT signatures for Level-2 selections: b-jets, tau-jets, and isolated...

Annovi, A.

2009-01-01

356

The slope of the GRB Variability/Peak Luminosity Correlation  

CERN Document Server

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

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

2006-01-01

357

Are low luminosity GRBs generated by relativistic jets?  

CERN Multimedia

Low luminosity gamma-ray bursts (ll-GRBs) constitute a sub-class of gamma-ray bursts (GRBs) that plays a central role in the GRB-supernova connection. While ll-GRBs differ from typical long GRBs (LGRBs) in many aspects, they also share some common features. Therefore, the question whether the gamma-ray emission of ll-GRBs and LGRBs has a common origin is of great interest. Here we address this question by testing whether ll-GRBs, like LGRBs according to the Collapsar model, can be generated by relativistic jets that punch holes in the envelopes of their progenitor stars. The collapsar model predicts that the durations of most observed bursts will be comparable to, or longer than, the time it takes the jets to breakout of the star. We calculate the jet breakout times of ll-GRBs and compare them to the observed durations. We find that there is a significant access of ll-GRBs with durations that are much shorter than the jet breakout time and that these are inconsistent with the Collapsar model. We conclude that...

Bromberg, Omer; Piran, Tsvi

2011-01-01

358

Tevatron energy and luminosity upgrades beyond the Main Injector  

International Nuclear Information System (INIS)

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 pp Collider to at least 1033cm-2sec-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 ?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 of a possible post-LHC ultra-high energy hadron collider

1994-01-01

359

Luminosity Bias. II. The Cosmic Web of the First Stars  

Science.gov (United States)

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

Barkana, R.

2013-05-01

360

Do Moderate-Luminosity AGN Suppress Star Formation?  

CERN Multimedia

The growth of supermassive black holes and their host galaxies are thought to be linked, but the precise nature of this symbiotic relationship is still poorly understood. Both observations and simulations of galaxy formation suggest that the energy input from active galactic nuclei (AGN), as the central supermassive black hole accretes material and grows, heats the interstellar material and suppresses star formation. In this Letter, we show that most host galaxies of moderate-luminosity supermassive black holes in the local universe have intermediate optical colors that imply the host galaxies are transitioning from star formation to quiescence, the first time this has been shown to be true for all AGN independent of obscuration. The intermediate colors suggest that star formation in the host galaxies ceased roughly 100 Myr ago. This result indicates that either the AGN are very long-lived, accreting for more than 1 Gyr beyond the end of star formation, or there is a ~100 Myr time delay between the shutdown o...

Schawinski, Kevin; Simmons, Brooke; Urry, C Megan; Treister, Ezequiel; Kaviraj, Sugata; Kushkuley, Bronika

2009-01-01

 
 
 
 
361

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

362

CONCERNING THE SLOPE OF THE CEPHEID PERIOD-LUMINOSITY RELATION  

International Nuclear Information System (INIS)

We discuss the impact of possible differences in the slope of the Cepheid period-luminosity (PL) relation on the determination of extragalactic distances in the context of recent studies that suggest changes in this slope. We show that the Wesenheit function W = V - R x (V - I), widely used for the determination of the Cepheid distances, is expected to be highly insensitive to changes in the slope of the underlying (monochromatic) PL relations. This occurs because the reddening trajectories in the color-magnitude plane are closely parallel to lines of constant period. As a result W-based PL relations have extremely low-residual dispersion, which is because differential (and the total line of sight) reddening is eliminated in the definition of W and the residual scatter due to a star's intrinsic color/position within the Cepheid is also largely insensitive to W. Basic equations are presented and graphically illustrated, showing the insensitivity of W to changes in the monochromatic PL relations.

2009-05-10

363

ATLAS ALFA—measuring absolute luminosity with scintillating fibres  

CERN Document Server

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

Franz, S

2009-01-01

364

The luminosity-size relation of galaxies to z=1?  

CERN Document Server

We use the Hubble Ultra Deep Field (UDF) to study the galaxy luminosity-size (M-Re) distribution. With a careful analysis of selection effects due to both detection completeness and measurement reliability we identify bias-free regions in the M-Re plane for a series of volume-limited samples. We also investigate the colour-log(n) distribution of these galaxies and further subdivide our data by structural type to separately study compact and diffuse objects. By comparison to the nearby Millennium Galaxy Catalogue, we present tenative evidence for evolution of diffuse, disk-like galaxies with redshift -- both in mean surface brightness and the slope of the M-Re relation. In contrast we find no evidence of structural evolution in the compact galaxy M-Re relation over this redshift range, although there is a suggestion of colour evolution. We also highlight the importance of considering surface brightness dependent measurement biases in addition to incompleteness biases. In particular, the increasing, systematic ...

Cameron, E

2007-01-01

365

On resonance parameter measurement and luminosity determination at e+e- collider  

CERN Multimedia

Expounded are the parameter measurement for narrow resonance and determination of corresponding luminosity at e+e- collider. The detailed theoretical formulas are compiled and the crucial experimental effects on observed cross section are taken into account. For luminosity determination, the iteration method is put forth which is mainly used to separate the interference effect between resonance and non-resonance decays.

Wang, P; Mo, X H

2009-01-01

366

Calculation of integrated luminosity for beams stored in the Tevatron collider  

Energy Technology Data Exchange (ETDEWEB)

A model for calculating the integrated luminosity of beams stored in the Tevatron collider will be presented. The model determines the instantaneous luminosity by calculating the overlap integral of bunched beams passing through the interaction region. The calculation accounts for the variation in beam size due to the beta functions and also for effects due to finite longitudinal emittance and non-zero dispersion in the interaction region. The integrated luminosity is calculated for the beams as they evolve due to processes including collisions and intrabeam scattering. The model has been applied to both the extant and upgraded Tevatron collider, but is not limited to them. The original motivation for developing the computer model was to determine the reduction in luminosity due to beams with non-zero longitudinal emittances. There are two effects: the transverse beam size is increased where the dispersion is non-zero; the finite length of the beam bunch combined with an increasing /beta/ function results in an increased transverse beam size at the ends of the bunch. The derivation of a sufficiently useful analytic expression for the luminosity proved to be intractable. Instead, a numerical integration computer program was developed to calculate the luminosity in the presence of a finite longitudinal emittance. The program was then expanded into a model which allows the luminosity to vary due to changes in emittances and reduction in bunch intensities. At that point, it was not difficult to calculate the integrated luminosity. 5 refs., 2 figs., 4 tabs.

Finley, D.A.

1989-03-20

367

Luminosity Improvement at PEP-II Based on Optics Model and Beam-Beam Simulation  

Energy Technology Data Exchange (ETDEWEB)

Since the beginning of this year, we have made significant improvements in the machine optics at PEP-II. As a result, the specific luminosity increased nearly 20%. The largest luminosity gain actually came from minimizing nonlinear chromatic effects and running both rings much closer to the half integer resonance in the horizontal plane.

Cai, Y.; Colocho, W.; Diecker, F-J.; Nosochkov, Y.; Raimondi, P.; Seeman, J.; Sonnad, K.; Sullivan, M.; Turner, J.; Weaver, M.; Wienands, U.; Wittmer, W.; Woodley, M.; Yan, Y.; Yock, G.; /SLAC

2006-06-21

368

NEARBY GALAXIES IN THE 2 ?m ALL SKY SURVEY. I. K-BAND LUMINOSITY FUNCTIONS  

International Nuclear Information System (INIS)

Differential Ks -band luminosity functions (LFs) are presented for a complete sample of 1613 nearby bright galaxies segregated by visible morphology. The LF for late-type spirals follows a power law that rises toward low luminosities whereas the LFs for ellipticals, lenticulars, and bulge-dominated spirals are peaked and decline toward both higher and lower luminosities. Each morphological type (E, S0, S0/a-Sab, Sb-Sbc, Sc-Scd) contributes approximately equally to the overall Ks -band luminosity density of galaxies in the local universe. Type averaged bulge/disk ratios are used to subtract the disk component leading to the prediction that the Ks -band LF for bulges is bimodal with ellipticals dominating the high luminosity peak, comprising 60% of the bulge luminosity density in the local universe with the remaining 40% contributed by lenticulars and the bulges of spirals. Overall, bulges contribute 30% of the galaxy luminosity density at Ks in the local universe with spiral disks making up the remainder. If bulge luminosities indicate central black hole (BH) masses, then our results predict that the BH mass function is also bimodal.

2009-09-10

369

Luminosity excesses in low-mass young stellar objects - a statistical study  

International Nuclear Information System (INIS)

This paper presents a statistical study in which the observed total luminosity is compared quantitatively with an estimate of the stellar luminosity for a sample of 59 low-mass young stellar objects (YSOs) in the Taurus-Auriga complex. In 13 of the analyzed YSOs, luminosity excesses greater than 0.20 are observed together with greater than 0.6 IR excesses, which typically contribute the bulk of the observed excess luminosity and are characterized by spectral energy distributions which are flat or rise toward long wavelengths. The analysis suggests that YSOs showing the largest luminosity excesses typically power optical jets and/or molecular outflows or have strong winds, as evidenced by the presence of O I emission, indicating a possible correlation between accretion and mass-outflow properties. 38 references.

1988-01-01

370

Luminosity excesses in low-mass young stellar objects - a statistical study  

Energy Technology Data Exchange (ETDEWEB)

This paper presents a statistical study in which the observed total luminosity is compared quantitatively with an estimate of the stellar luminosity for a sample of 59 low-mass young stellar objects (YSOs) in the Taurus-Auriga complex. In 13 of the analyzed YSOs, luminosity excesses greater than 0.20 are observed together with greater than 0.6 IR excesses, which typically contribute the bulk of the observed excess luminosity and are characterized by spectral energy distributions which are flat or rise toward long wavelengths. The analysis suggests that YSOs showing the largest luminosity excesses typically power optical jets and/or molecular outflows or have strong winds, as evidenced by the presence of O I emission, indicating a possible correlation between accretion and mass-outflow properties. 38 references.

Strom, K.M.; Strom, S.E.; Kenyon, S.J.; Hartmann, L.

1988-02-01

371

Correlations between MIR, FIR, H$\\alpha$, and FUV Luminosities for SWIRE galaxies  

CERN Document Server

e present and analyze the correlations between mid-infrared (MIR), far-infrared (FIR), total-infrared (TIR), H$\\alpha$, and FUV luminosities for star-forming galaxies, composite galaxies and AGNs, based on a large sample of galaxies selected from the $Spitzer$ SWIRE fields. The MIR luminosities of star-forming galaxies are well correlated with their H$\\alpha$, TIR and FUV luminosities, and we re-scaled the MIR-derived SFR formulae according to the above correlations with differences less than 15%. We confirm the recent result by calzetti et al. (2007) that the combined observed H$\\alpha$ + 24$\\mu$m luminosities L(H$\\alpha IR and TIR luminosities are completely following those of star-forming galaxies.

Zhu, Yi-Nan; Cao, Chen; Li, Hai-Ning

2008-01-01

372

A Study of Small Angle Radiative Bhabha Scattering and Measurement of the Luminosity at SLD  

Energy Technology Data Exchange (ETDEWEB)

Small angle Bhabha scattering (e{sup +}e{sup -} {yields} e{sup +}e{sup -}) is used to measure the luminosity for the 1993 run of the SLD experiment. SLD operates at the Stanford Linear Collider at Stanford Linear Accelerator Center where electrons and positrons are collided at center of mass energy on the Z{sup 0} resonance. A silicon tungsten luminosity monitor is used to record the Bhabha events and a description of this device and its performance is presented. The luminosity is measured using two different methods to correct for small displacements in the luminosity monitor and the results are given. Measurement of the integrated luminosity is essential for the determination of the cross section for all final states in the experiment.

White, S

2004-01-05

373

Luminosity dependence in the ratio of X-ray to infrared emission of QSOs  

International Nuclear Information System (INIS)

[en] The correlation of X-ray and near-infrared luminosity is studied for a sample of radio-quiet QSOs. The X-ray to infrared ratio is found to decrease as the infrared luminosity increases. No preference is found between the correlations of X-ray luminosity with optical or infrared luminosity. This implies that optical and infrared emission are equally good predictors of X-ray emission. Source models which directly link infrared and X-ray emission are discussed, and a preference is found for a specific synchrotron self-Compton model. This model predicts the correct luminosity dependence of the X-ray to infrared ratio if certain conditions apply. 55 references

1987-01-01

374

Oxygen abundances in dwarf irregular galaxies and the metallicity - luminosity relationship  

CERN Multimedia

The low-luminosity dwarf irregular galaxies are considered. The oxygen abundances in HII regions of dwarf irregular galaxies were recalculated from published spectra through the recently suggested P - method. It has been found that the metallicity of low-luminosity dwarf irregular galaxies, with a few exceptions, correlates well with galaxy luminosity. The dispersion of oxygen abundances around the metallicity - luminosity relationship increases with decreasing of galaxy luminosity, as was found by Richer and McCall (1995). No relationship between the oxygen abundance and the absolute magnitude in the blue band for irregular galaxies obtained by Hidalgo-Gamez and Olofsson (1998) can be explained by the large uncertainties in the oxygen abundances derived through the Te - method, that in turn can be explained by the large uncertainties in the measurements of the strengths of the weak oxygen line [OIII]4363 used in the Te - method.

Pilyugin, L S

2001-01-01

375

Optical Luminosities and Mass-to-Light Ratios of Nearby Galaxy Clusters  

CERN Document Server

We analyze a sample of 105 clusters having virial mass homogeneously estimated and for which galaxy magnitudes are available with a well defined high degree of completeness. In particular, we consider a subsample of 89 clusters with B_j band galaxy magnitudes taken from the COSMOS/UKST Southern Sky Object Catalogue. We compute cluster luminosities L_{B_j} within several clustercentric distances and within the virialization radius R_{vir}. In particular, we use the luminosity function and background counts estimated by Lumsden et al. (1997) on the Edinburgh/Durham Southern Galaxy Catalogue. We analyze the effect of several uncertainties connected to photometric data, fore/background removal, and extrapolation below the completeness limit of the photometry, in order to assess the robustness of our cluster luminosity estimates. We draw our results on the relations between luminosity and dynamical quantities from the COSMOS sample by considering mass and luminosities determined within the virialization radius. We...

Girardi, M; Giuricin, G; Mardirossian, F; Mezzetti, M

1999-01-01

376

Luminosity dependence in the ratio of X-ray to infrared emission of QSOs  

Energy Technology Data Exchange (ETDEWEB)

The correlation of X-ray and near-infrared luminosity is studied for a sample of radio-quiet QSOs. The X-ray to infrared ratio is found to decrease as the infrared luminosity increases. No preference is found between the correlations of X-ray luminosity with optical or infrared luminosity. This implies that optical and infrared emission are equally good predictors of X-ray emission. Source models which directly link infrared and X-ray emission are discussed, and a preference is found for a specific synchrotron self-Compton model. This model predicts the correct luminosity dependence of the X-ray to infrared ratio if certain conditions apply. 55 references.

Worrall, D.M.

1987-07-01

377

An investigation of X-ray luminosity versus crystalline powder granularity  

Science.gov (United States)

At the High-Throughput Discovery of Scintillator Materials Facility at Lawrence Berkeley National Laboratory, scintillators are synthesized by solid-state reaction or melt mixing, forming crystalline powders. These powders are formed in various granularity and the crystal grain size affects the apparent luminosity of the scintillator. To accurately predict a “full-size” scintillator's crystal luminosity, the crystal luminosity as a function of crystal granularity size has to be known. In this study, we examine Bi4Ge3O12 (BGO), Lu2SiO5:Ce3+ (LSO), YAlO3:Ce3+(YAP:Ce), and CsBa2I5:Eu2+ (CBI) luminosities as a function of crystalline grain size. The highest luminosities were measured for 600- to 1000-?m crystal grain sizes for BGO and LSO, for 310- to 600-?m crystal grain sizes for CBI, and for crystal grains larger than 165 ?m for YAP:Ce. Crystal grains that were larger than 1 mm had a lower packing fraction, and smaller grains were affected by internal scattering. We measured a 34% decrease in luminosity for BGO when decreasing from the 600- to 1000-?m crystal grain size range down to the 20- to 36-?m range. The corresponding luminosity decrease for LSO was 44% for the same grain size decrease. YAP:Ce exhibited a luminosity decrease of 47% when the grain size decreased from the 165- to 310-?m crystal grains to the 20- to 36-?m range, and CBI exhibited a luminosity decrease of 98% when the grain size decreased from the 310- to 600-?m crystal grain range to the 36- to 50-?m range. We were able to very accurately estimate full-size crystal luminosities from crystalline grains that are larger than 90 ?m.

Janecek, Martin; Borade, Ramesh; Bourret-Courchesne, Edith; Derenzo, Stephen E.

2011-12-01

378

SuperB: a Linear High-Luminosity B Factory  

Energy Technology Data Exchange (ETDEWEB)

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

Albert, J.; Bettarini, S.; Biagini, M.; Bonneaud, G.; Cai, Y.; Calderini, G.; Ciuchini, M.; Dubois-Felsmann, G.P.; Ecklund, S.; Forti, F.; Gershon, T.J.; Giorgi, M.A.; Hitlin, D.G.; Leith, D.W.G.S.; Lusiani, A.; MacFarlane, D.B.; Martinez-Vidal, F.; Neri, N.; Novokhatski, A.; Pierini, M.; Piredda, G.; /Caltech /Pisa U. /Pisa, Scuola Normale

2006-02-08

379

Correlation between the Peak Spectral Energy of Gamma-Ray Bursts and the Peak Luminosity of the Underlying Supernovae: Implication for the Nature of GRB-SN Connection  

CERN Multimedia

In this paper we present a correlation between the peak spectral energy of gamma-ray bursts (GRBs) and the peak bolometric luminosity of the underlying supernovae (SNe), based on a sample of four pairs of GRBs-SNe with spectroscopically confirmed connection. Combining it with the well-known relation between the peak spectral energy and the isotropic equivalent energy of GRBs, we obtain an upper limit on the isotropic energy of GRBs, which is \\approx 10^{52} erg (L_{SN,peak}/10^{43} erg s^{-1})^{10}, where L_{SN,peak} is the peak bolometric luminosity of the SNe. Our results suggest that the critical parameter determining the GRB-SN connection is the peak luminosity of SNe, rather than the feature of the SN spectra and/or the SN explosion energy as commonly hypothesized. Since it is generally believed that the peak luminosity of SNe powered by radioactive decays is related to the amount of 56Ni produced in the SN explosion, the mass of 56Ni may be a key physical factor for understanding the nature of GRBs and ...

Li, L X

2006-01-01

380

CO Luminosity Functions For FIR and B-band Selected Galaxies and the First Estimate for Omega_{HI+H2}  

CERN Document Server

We derive a non-parametric CO luminosity function using a FIR and an optical B-band selected sample of the galaxies included in the FCRAO Extragalactic CO Survey. The FIR selected sample is defined using the IRAS Bright Galaxy Surveys (BGS; IRAS 60 micron flux density >= 5.24 Jy). Although our CO sample is not complete, the normalization using the BGS reproduces the IRAS 60 micron luminosity function in excellent agreement with those found in the literature. Similarly, a B-band selected sample defined using the Revised Shapley-Ames (RSA) catalog is used to derive a CO luminosity function for a comparison. A Schechter function describes the both derived CO luminosity functions reasonably well. Adopting the standard CO-to-H2 conversion factor, we derive a molecular gas density of rho_{H2}=(3.1\\pm 1.2)*10^7h Mo Mpc^{-3} for the local volume. Combining with the measurements of the local HI mass density and the helium contribution, we estimate that the total mass density of cold neutral gas in the local universe i...

Keres, D; Young, J S; Keres, Dusan; Yun, Min S.

2003-01-01

 
 
 
 
381

Evidence Against an Edge-On Disk Around the Extrasolar Planet 2MASS 1207 b and a New Thick Cloud Explanation for its Under-Luminosity  

CERN Document Server

(Abridged) Since the discovery of the first directly-imaged, planetary-mass object, 2MASS 1207 b, several works have sought to explain a disparity between its observed temperature and luminosity. Given its known age, distance, and spectral type, 2MASS 1207 b is under-luminous by a factor of ~10 (~2.5 mags) when compared to standard models of brown-dwarf/giant-planet evolution. In this paper, we study three possible sources of 2MASS 1207 b's under-luminosity. First, we investigate Mohanty et al. (2007)'s hypothesis that a near edge-on disk might be responsible for 2MASS 1207 b's under-luminosity. We conclude that the hypothesis is unlikely due to the lack of variability seen in multi-epoch photometry and unnecessary due to the increasing sample of under-luminous brown-dwarfs/giant-exoplanets that cannot be explained by an edge-on disk. Next, we test the analogous possibility that a spherical shell of dust, could explain 2MASS 1207 b's under-luminosity. Models containing enough dust to create ~2.5 mags of extin...

Skemer, Andrew J; Sz\\Hucs, László; Apai, Dániel; Pascucci, Ilaria; Biller, Beth A

2011-01-01

382

The broad line and gamma-ray luminosity relation in Fermi blazars  

CERN Multimedia

We study the relation between the mass accretion rate, the jet power, and the black hole mass of blazars. To this aim, we make use of the Sloan Digital Sky Survey (SDSS) and the 11 months catalog of blazars detected at energies larger than 100 MeV by the Large Area Telescope (LAT) onboard the Fermi satellite. This allows to construct a relatively large sample of blazars with information about the luminosity (or upper limits) of their emission lines used as a proxy for the strength of the disk luminosity and on the luminosity of the high energy emission, used as a proxy for the jet power. We find a good correlation between the luminosity of the broad lines and the gamma-ray luminosity as detected by Fermi, both using absolute values of the luminosities and normalising them to the Eddington value. We confirm that the division of blazars into BL Lacs and Flat Spectrum Radio Quasars (FSRQs) is controlled by the line luminosity in Eddington units. If this ratio is smaller than 5x10^-4 the object is a BL Lac, while...

Sbarrato, T; Maraschi, L; Colpi, M

2011-01-01

383

DISTRIBUTION OF MAXIMAL LUMINOSITY OF GALAXIES IN THE SLOAN DIGITAL SKY SURVEY  

Energy Technology Data Exchange (ETDEWEB)

Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index {xi}, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high-luminosity end. Assuming, however, {xi} = 0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided that uncertainties arising from both the finite batch size and the batch-size distribution are accounted for. For a volume-limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided that the uncertainties related to batch-size distribution are taken care of.

Taghizadeh-Popp, M.; Szalay, A. S. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Ozogany, K.; Racz, Z. [Institute for Theoretical Physics-HAS, Eoetvoes University, Pazmany setany 1/a, 1117 Budapest (Hungary); Regoes, E., E-mail: mtaghiza@pha.jhu.edu [European Laboratory for Particle Physics (CERN), Geneva (Switzerland)

2012-11-10

384

DISTRIBUTION OF MAXIMAL LUMINOSITY OF GALAXIES IN THE SLOAN DIGITAL SKY SURVEY  

International Nuclear Information System (INIS)

[en] Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index ?, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high-luminosity end. Assuming, however, ? = 0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided that uncertainties arising from both the finite batch size and the batch-size distribution are accounted for. For a volume-limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided that the uncertainties related to batch-size distribution are taken care of.

2012-11-10

385

Distribution of Maximal Luminosity of Galaxies in the Sloan Digital Sky Survey  

Science.gov (United States)

Extreme value statistics is applied to the distribution of galaxy luminosities in the Sloan Digital Sky Survey. We analyze the DR8 Main Galaxy Sample (MGS), as well as the luminous red galaxies (LRGs). Maximal luminosities are sampled from batches consisting of elongated pencil beams in the radial direction of sight. For the MGS, results suggest a small and positive tail index ?, effectively ruling out the possibility of having a finite maximum cutoff luminosity, and implying that the luminosity distribution function may decay as a power law at the high-luminosity end. Assuming, however, ? = 0, a non-parametric comparison of the maximal luminosities with the Fisher-Tippett-Gumbel distribution (limit distribution for variables distributed by the Schechter fit) indicates a good agreement provided that uncertainties arising from both the finite batch size and the batch-size distribution are accounted for. For a volume-limited sample of LRGs, results show that they can be described as being the extremes of a luminosity distribution with an exponentially decaying tail, provided that the uncertainties related to batch-size distribution are taken care of.

Taghizadeh-Popp, M.; Ozogány, K.; Rácz, Z.; Regoes, E.; Szalay, A. S.

2012-11-01

386

The European Large Area ISO Survey IV the preliminary 90 micron luminosity function  

CERN Multimedia

We present the luminosity function of 90um selected galaxies from the European Large Area ISO Survey (ELAIS), extending to z=0.3. Their luminosities are in the range 10^9 = 100mJy database, we found optical, 15um or 1.4GHz identifications for 24 (65%). We have obtained 2dF and UK Schmidt FLAIR spectroscopy of 89% of IDs to rigid multivariate flux limits. We construct a luminosity function assuming (a) our spectroscopic subset is an unbiased sparse sample, and (b) there are no galaxies which would not be represented in our spectroscopic sample at {\\it any} redshift. We argue that we can be confident of both assumptions. We find the luminosity function is well-described by the local 100um luminosity function of Rowan-Robinson, Helou & Walker (1987). {\\it Assuming} this local normalisation, we derive luminosity evolution of (1+z)^{2.45\\pm0.85} (95% confidence). We argue that star formation dominates the bolometric luminosities of these galaxies and we derive comoving star formation rates in broad agreement w...

Serjeant, S; Oliver, S; Surace, C; Heraudeau, P; Linden-Voernle, M J D; Gruppioni, C; La Franca, F; Rigopoulou, D; Morel, T; Crockett, H; Sumner, T J; Rowan-Robinson, M; Graham, M

2000-01-01

387

On the metallicity dependence of the 24micron luminosity as a star formation tracer  

CERN Multimedia

We investigate the use of the rest-frame 24microns luminosity as an indicator of the star formation rate (SFR) in galaxies with different metallicities by comparing it to the (extinction corrected) Halpha luminosity. We carry out this analysis in 2 steps: First, we compare the emission from HII regions in different galaxies with metallicities between 12+log(O/H) = 8.1 and 8.9. We find that the 24microns and the extinction corrected Halpha luminosities from individual HII regions follow the same correlation for all galaxies, independent of their metallicity. Second, the role of metallicity is explored further for the integrated luminosity in a sample of galaxies with metallicities in the range of 12+log(O/H) = 7.2 - 9.1. For this sample we compare the 24microns and Halpha luminosities integrated over the entire galaxies and find a lack of the 24microns emission for a given Halpha luminosity for low metallicity objects, likely reflecting a low dust content. These results suggest that the 24microns luminosity is...

Relano, M; Pérez-González, P G; Vílchez, J M; Battaner, E

2007-01-01

388

The European Large Area ISO Survey - IV. The preliminary 90-mu m luminosity function  

DEFF Research Database (Denmark)

We present the luminosity function of 90-mum-selected galaxies from the European Large Area ISO Survey (ELAIS), extending to z = 0.3. Their luminosities are in the range 10(9) luminosity function assuming that (i) our spectroscopic subset is an unbiased sparse sample, and (ii) there are no galaxies that would not be represented in our spectroscopic sample at any redshift. We argue that we can be confident of both assumptions. We find that the luminosity function is well described by the local 100-mum luminosity function of Rowan-Robinson, Helou & Walker. Assuming this local normalization, we derive luminosity evolution of (1 +z)(2.45 + .0.85) (95 per cent confidence). We argue that star formation dominates the bolometric luminosities of these galaxies, and we derive comoving star formation rates in broad agreement with the Flores et al. and Rowan-Robinson et al. mid-infrared-based estimates.

Serjeant, S.; Efstathiou, A.

2001-01-01

389

Luminosity for e-e- linear collider designs at 1.7 TeV  

Energy Technology Data Exchange (ETDEWEB)

The total luminosity for e{sup -}e{sup -} mode compared to that for e{sup +}e{sup -} mode is severely reduced in a very high energy linear collider, because the mutual disruption of the beams blows up the beams instead of pinching them down. However, since an e{sup -}e{sup -} machine has less beamstrahlung than an e{sup -}e{sup -} machine with the same parameters, the luminosity near the peak energy is not degraded as much as the total luminosity. We quantify these effects for two representative designs at 1.7 TeV center of mass.

Thompson, Kathleen A

2002-09-13

390

The D-Zero luminosity monitor constant for {radical} {ital s} = 630 GeV  

Energy Technology Data Exchange (ETDEWEB)

D0 has calculated the luminosity monitor constant for {radical}s= 630 GeV. The inelastic p{anti p} cross section was interpolated between measurements performed at {radical}s = 546 and 1800 GeV. The geometric acceptance, hardware efficiency, and luminosity-dependent corrections are similar to those previously published for the full Tevatron energy. We find a luminosity-weighted value of {sigma}{sub L0} = 34.04 {+-} 1.05 mb, yielding a precision of {+-} 3.08%.

Krane, J.; Barnly, J.; Owen, D.

1997-06-01

391

Star Formation Rates for Starburst Galaxies from Ultraviolet, Infrared, and Radio Luminosities  

CERN Multimedia

Star formation rates (SFR) are compared as determined from mid-infrared 7.7 um 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 700 for the most luminous starbursts at z ~ 2.5. With this amount of extinction, the optical magnitude of a starburst having fv(7.7 um) of 1 mJy should be V ~ 25.6.

Sargsyan, Lusine A

2009-01-01

392

High luminosity, electron-positron colliders as strangeness, charm, and beauty factories  

International Nuclear Information System (INIS)

This paper reports on high luminosity electron-positron colliders operating at the mass of the ? meson (1.02 GeV) that can produce copious K bar K0 pairs from a single quantum state. Temporal correlations in the decays of the K's provide a measure of the direct CP violating amplitude and also allow a high precision test of CPT invariance. A low energy collider with high luminosity can serve as a beam physics testbed to evaluate novel approaches to collider design that may be necessary for B factories to attain luminosities ? 1024 cm-2s-1

1990-01-01

393

THE GALAXY OPTICAL LUMINOSITY FUNCTION FROM THE AGN AND GALAXY EVOLUTION SURVEY  

International Nuclear Information System (INIS)

[en] We present the galaxy optical luminosity function for the redshift range 0.05 2 in the Boötes field of the NOAO Deep Wide-Field Survey. Our statistical sample is composed of 12,473 galaxies with known redshifts down to I = 20.4 (AB). Our results at low redshift are consistent with those from Sloan Digital Sky Survey; at higher redshift, we find strong evidence for evolution in the luminosity function, including differential evolution between blue and red galaxies. We find that the luminosity density evolves as (1 + z)(0.54±0.64) for red galaxies and (1 + z)(1.64±0.39) for blue galaxies.

2012-03-20

394

THE WYOMING SURVEY FOR H?. II. H? LUMINOSITY FUNCTIONS AT z? 0.16, 0.24, 0.32, AND 0.40  

International Nuclear Information System (INIS)

[en] The Wyoming Survey for H?, or WySH, is a large-area, ground-based imaging survey for H?-emitting galaxies at redshifts of z ? 0.16, 0.24, 0.32, and 0.40. The survey spans up to 4 deg2 in a set of fields of low Galactic cirrus emission, using twin narrowband filters at each epoch for improved stellar continuum subtraction. H? luminosity functions are presented for each ?z ? 0.02 epoch based on a total of nearly 1200 galaxies. These data clearly show an evolution with look-back time in the volume-averaged cosmic star formation rate. Integrals of Schechter fits to the incompleteness- and extinction-corrected H? luminosity functions indicate star formation rates per comoving volume of 0.010, 0.013, 0.020, 0.022 h 70 M sun yr-1 Mpc-3 at z ? 0.16, 0.24, 0.32, and 0.40, respectively. Combined statistical and systematic measurement uncertainties are on the order of 25%, while the effects of cosmic variance are at the 20% level. The bulk of this evolution is driven by changes in the characteristic luminosity L * of the H? luminosity functions, with L * for the earlier two epochs being a factor of 2 larger than L * at the latter two epochs; it is more difficult with this data set to decipher systematic evolutionary differences in the luminosity function amplitude and faint-end slope. Coupling these results with a comprehensive compilation of results from the literature on emission line surveys, the evolution in the cosmic star formation rate density over 0 ?

395

A power scalable 10-bit pipeline ADC for Luminosity Detector at ILC  

Energy Technology Data Exchange (ETDEWEB)

The design and measurement results of a power scalable 10-bit pipeline ADC developed for the luminosity detector at the future International Linear Collider (ILC) are discussed. The prototype is designed and fabricated in 0.35 {mu}m CMOS technology. A wide spectrum of measurements of static (INL < 1 LSB, DNL < 0.5 LSB) and dynamic (SNHR > 58 dB, SINAD {approx} 58 dB) parameters are performed to understand and quantify the circuit performance. The ADC works for sampling rates from 1 kS/s to 25 MS/s covering more than four orders of magnitude. In most of the range power consumption scales linearly with sampling rate with a factor of 0.85 mW/MS/s. With ILC beam structure and sampling rate of about 3.5 MS/s, using the implemented in ASIC power switching off feature, an average power consumption of about 15 {mu}W per channel may be obtained. The ADC layout is drawn with a constant pitch of 300 {mu}m to facilitate a multichannel implementation.

Idzik, M; Swientek, K; Fiutowski, T; Kulis, S; Ambalathankandy, P, E-mail: idzik@ftj.agh.edu.pl [Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. Mickiewicza 30, Cracow (Poland)

2011-01-15

396

A power scalable 10-bit pipeline ADC for Luminosity Detector at ILC  

International Nuclear Information System (INIS)

The design and measurement results of a power scalable 10-bit pipeline ADC developed for the luminosity detector at the future International Linear Collider (ILC) are discussed. The prototype is designed and fabricated in 0.35 ?m CMOS technology. A wide spectrum of measurements of static (INL 58 dB, SINAD ? 58 dB) parameters are performed to understand and quantify the circuit performance. The ADC works for sampling rates from 1 kS/s to 25 MS/s covering more than four orders of magnitude. In most of the range power consumption scales linearly with sampling rate with a factor of 0.85 mW/MS/s. With ILC beam structure and sampling rate of about 3.5 MS/s, using the implemented in ASIC power switching off feature, an average power consumption of about 15 ?W per channel may be obtained. The ADC layout is drawn with a constant pitch of 300 ?m to facilitate a multichannel implementation.

2011-01-01

397

Luminosity Function Constraints on the Evolution of Massive Red Galaxies Since z~0.9  

CERN Multimedia

We measure the evolution of the luminous red galaxy (LRG) luminosity function in the redshift range 0.13L*) red galaxies have grown by less than 50% (at 99% confidence), since z=0.9, in stark contrast to the factor of 2-4 growth observed in the L* red galaxy population over the same epoch. We also investigate the evolution of the average LRG spectrum since z~0.9 and find the high-redshift composite to be well-described as a passively evolving example of the composite galaxy observed at low-redshift. From spectral fits to the composite spectra, we find at most 5% of the stellar mass in massive red galaxies may have formed within 1Gyr of z=0.9. While L* red galaxies are clearly assembled at z<1, 3L* galaxies appear to be largely in place and evolve little beyond the passive evolution of their stellar populations over the last half of c osmic history.

Cool, Richard J; Fan, Xiaohui; Fukugita, Masataka; Jiang, Linhua; Maraston, Claudia; Meiksin, Avery; Schneider, Donald P; Wake, David A

2008-01-01

398

The Bright End of the UV Luminosity Function at z~8: New Constraints from CANDELS Data  

CERN Document Server

We present new z~8 galaxy candidates from a search over ~95 arcmin^2 of WFC3/IR data. These are used to determine the bright end of the UV luminosity function (LF) of star-forming galaxies at z~8. Our analysis is based on newly acquired WFC3/IR imaging data obtained as part of the CANDELS Multi-Cycle Treasury program over the GOODS South field, which allows us to triple the search area for bright z~8 galaxies in the GOODS South. These new data are combined with existing deep optical ACS imaging to search for relatively bright (M_UV<-19.5 mag) z~8 galaxy candidates using the Lyman Break technique. To minimize contamination from lower redshift galaxies, we make full use of all optical data and impose strict non-detection criteria based on an optical chi^2_opt flux measurement. In the whole search area we identify 11 candidate z~8 galaxies, spanning a magnitude range H_160,AB =25.8-27.5 mag. The new data show that the UV LF is a factor ~2 lower at M_UV < -19.5 mag than previously determined. Combining this...

Oesch, P A; Illingworth, G D; Gonzalez, V; Trenti, M; van Dokkum, P G; Franx, M; Labbe, I; Carollo, C M; Magee, D

2012-01-01

399

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

International Nuclear Information System (INIS)

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

2009-01-01

400

Galaxy luminosity function per morphological type up to z=1.2  

CERN Multimedia

We have computed the evolution of the rest-frame B-band luminosity function (LF) for bulge and disk-dominated galaxies since z=1.2. We use a sample of 605 spectroscopic redshifts with I_{AB}0.9 and bright galaxies showing a strongly decreasing LF slope \\alpha=+0.55 \\pm 0.21, and 32% of blue (B-I)_{AB}<0.9 and more compact galaxies which populate the LF faint-end. We observe that red bulge-dominated galaxies are already well in place at z~1, but the volume density of this population is increasing by a factor 2.7 between z~1 and z~0.6. It may be related to the building-up of massive elliptical galaxies in the hierarchical scenario. In addition, we observe that the blue bulge-dominated population is dimming by 0.7 magnitude between z~1 and z~0.6. Galaxies in this faint and more compact population could possibly be the progenitors of the local dwarf spheroidal galaxies.

Ilbert, O; Tresse, L; Buat, V; Arnout, S; Lefèvre, O; Burgarella, D; Zucca, E; Bardelli, S; Zamorani, G; Bottini, D; Garilli, B; Le Brun, V; 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; Pozzetti, L; Radovich, M; Bondi, M; Bongiorno, A; Busarello, G; Ciliegi, P; Mellier, Y; Merluzzi, P; Ripepi, V; Rizzo, D

2006-01-01

 
 
 
 
401

The Durham/UKST Galaxy Redshift Survey; 2, The Field Galaxy Luminosity Function  

CERN Multimedia

We present the results for the galaxy luminosity function as estimated from the Durham/UKST Galaxy Redshift Survey. This survey is magnitude limited to bj = 17, contains 2500 galaxies sampled at a rate of one in three and surveys a 4 x 10^6 Mpc^3 volume of space. The maximum likelihood parameters for a standard Schechter luminosity function are estimated to be M*bj = -19.72+-0.09, alpha = -1.14+-0.08 and phi* = (1.2 +- 0.2) x 10^-2 ( h^3Mpc^-3). A comparison with galaxy luminosity functions from other redshift surveys shows good agreement and the shape of the luminosity function now appears well-defined down to Mbj = -17. There are some discrepancies between the different surveys for galaxies fainter than this absolute magnitude. However, our estimate agrees well with that from the APM-Stromlo Galaxy Redshift Survey and we measure a fairly flat faint end slope.

Ratcliffe, A; Parker, Q A; Fong, R

1997-01-01

402

On the nature of `off' states in slowly rotating low-luminosity X-ray pulsars  

CERN Multimedia

We elaborate on a recently proposed model for subsonic quasi-spherical accretion onto slowly rotating pulsars, in which accretion is mediated through a hot quasi-static shell above the neutron star magnetosphere. We show that under the same external conditions, two regimes of subsonic accretion are possible, depending on if plasma cooling in the transition zone is dominated by Compton or radiative processes. We suggest that a transition from the higher luminosity Compton cooling regime to the lower luminosity radiative cooling regime can be responsible for the onset of the `off'-states repeatedly observed in several low luminosity slowly accreting pulsars, such as Vela X-1, GX 301-2 and 4U 1907+09. We further suggest that the triggering of the transition may be due to a switch in the X-ray beam pattern in response to a change in the optical depth in the accretion column with changing luminosity.

Shakura, N; Hjalmarsdotter, L

2012-01-01

403

The UV Galaxy Luminosity Function in the Local Universe from GALEX Data  

CERN Document Server

We present the results of a determination of the galaxy luminosity function at ultraviolet wavelengths at redshifts of $z=0.0-0.1$ from GALEX data. We determined the luminosity function in the GALEX FUV and NUV bands from a sample of galaxies with UV magnitudes between 17 and 20 that are drawn from a total of 56.73 deg^2 of GALEX fields overlapping the b_j-selected 2dF Galaxy Redshift Survey. The resulting luminosity functions are fainter than previous UV estimates and result in total UV luminosity densities of 10^(25.55+/-0.12) ergs s^-1 Hz^-1 Mpc^-3 and 10^(25.72+/-0.12) ergs s^-1 Hz^-1 Mpc^-3 at 1530 Ang. and 2310 Ang., respectively. This corresponds to a local star formation rate density in agreement with previous estimates made with H-alpha-selected data for reasonable assumptions about the UV extinction.

Wyder, T K; Milliard, B; Schiminovich, D; Arnouts, S; Budavari, T; Barlow, T A; Bianchi, L; Byun, Y I; Donas, J; Forster, K; Friedman, P G; Heckman, T M; Jelinsky, P N; Lee, Y W; Madore, B F; Malina, R F; Martin, D C; Morrissey, P F; Neff, S G; Rich, R M; Siegmund, O H W; Small, T; Szalay, A S; Welsh, B Y; Wyder, Ted K.; Treyer, Marie A.; Milliard, Bruno; Schiminovich, David; Arnouts, St\\'ephane; Budav\\'ari, Tam\\'as; Barlow, Tom A.; Bianchi, Luciana; Byun, Yong-Ik; Donas, Jos\\'e; Forster, Karl; Friedman, Peter G.; Heckman, Timothy M.; Jelinsky, Patrick N.; Lee, Young-Wook; Madore, Barry F.; Malina, Roger F.; Morrissey, Patrick; Neff, Susan G.; Siegmund, Oswald H. W.; Small, Todd; Szalay, Alex S.; Welsh, Barry Y.

2004-01-01

404

Radio-loud AGN: is there a link between luminosity and cluster environment?  

CERN Multimedia

We present here the first results from the Chandra ERA (Environments of Radio-loud AGN) Large Project, characterizing the cluster environments of a sample of 26 radio-loud AGN at z ~ 0.5 that covers three decades of radio luminosity. This is the first systematic X-ray environmental study at a single epoch, and has allowed us to examine the relationship between radio luminosity and cluster environment without the problems of Malmquist bias. We have found a weak correlation between radio luminosity and host cluster X-ray luminosity, as well as tentative evidence that this correlation is driven by the subpopulation of low-excitation radio galaxies, with high-excitation radio galaxies showing no significant correlation. The considerable scatter in the environments may be indicative of complex relationships not currently included in feedback models.

Ineson, J; Hardcastle, M J; Kraft, R P; Evans, D A; Jarvis, M

2013-01-01

405

Cosmic Variance and Its Effect on the Luminosity Function Determination in Deep High z Surveys  

CERN Multimedia

We study cosmic variance in deep high redshift surveys and its influence on the determination of the luminosity function for high redshift galaxies. For several survey geometries relevant for HST and JWST instruments, we characterize the distribution of the galaxy number counts. This is obtained by means of analytic estimates via the two point correlation function in extended Press-Schechter theory as well as by using synthetic catalogs extracted from N-body cosmological simulations of structure formation. We adopt a simple luminosity - dark halo mass relation to investigate the environment effects on the fitting of the luminosity function. We show that in addition to variations of the normalization of the luminosity function, a steepening of its slope is also expected in underdense fields, similarly to what is observed within voids in the local universe. Therefore, to avoid introducing artificial biases, caution must be taken when attempting to correct for field underdensity, such as in the case of HST UDF i...

Trenti, M

2007-01-01

406

Luminosity measurement at LEP using the very small angle tagger of DELPHI  

International Nuclear Information System (INIS)

In this thesis, the analysis of the luminosity measurement from Bhabha scattering within the polar angular region (5 to 7 mrad) covered by the Very Small Angle Tagger (VSAT) in the DELPHI experiment at LEP, is presented. Both by analytical integration and using Monte Carlo simulation, it is shown that the acceptance corrections to the detector can be reliably calculated, obtaining a relative luminosity measurement at the precision level of 0.1%. The absolute experimental error on the luminosity measurement is estimated to be 0.8%. Furthermore, measurement of the beam spot using the VSAT detector are described. The application of the relative luminosity measurement in the extraction of the hadronic lineshape parameters of the Z-particle is also presented.

1993-01-01

407

M Dwarfs from Hubble Space Telescope Star Counts. V. The I-band Luminosity Function  

CERN Multimedia

We derive the disk I-band luminosity function from the Zheng et al. sample of \\~1400 disk M dwarfs observed with the Hubble Space Telescope. We adopt a Galactic-height-dependent color-magnitude relation to account for the metallicity gradient above the Galactic plane. The resultant I-band luminosity function peaks at M_I~9.5 and drops sharply toward M_I~10.5.

Zheng, Z; Gould, A; Bahcall, J N; Salim, S; Zheng, Zheng; Flynn, Chris; Gould, Andrew; Bahcall, John N.; Salim, Samir

2004-01-01

408

Formation rate, evolving luminosity function, jet structure, and progenitors for long Gamma Ray Bursts  

CERN Multimedia

We constrain the luminosity function and formation rate of long gamma-ray bursts (GRBs) by using both the observed peak flux and redshift distributions. From our analysis, evidence supporting an evolution of the luminosity function is found. We compare the inferred GRB formation rate history to the cosmic star formation history up to z~6. Some implications of our findings for the jet models, GRB event rate in the Milky Way, and possible progenitors are discussed.

Firmani, C; Ghisellini, G; Tutukov, A V

2004-01-01

409

Status of Precision Monte Carlo Tools for Luminosity Monitoring at Meson Factories  

Science.gov (United States)

We review recent progress in precision calculations and the development of Monte Carlo generators for luminosity monitoring at meson factories. It is shown how the theoretical accuracy reached by presently used large-angle Bhabha tools at meson factories is at the 0.1% level and, therefore, comparable with that reached about a decade ago for luminosity monitoring through small-angle Bhabha scattering at LEP.

Balossini, G.; Montagna, G.; Carloni Calame, C. M.; Nicrosini, O.; Piccinini, F.

2007-11-01

410

Modification of redshift and luminosity by voids in the expanding universe  

International Nuclear Information System (INIS)

[en] Propagation of light in a clumpy universe is examined for redshift and luminosity. Taking a spherical void model and Swiss Chesse model, the modification is found to be the third order of (Hrsub(b)/c) for the redshift and the first order of it for the luminosity, rsub(b) being the radius of a void or a Swiss Cheese hole. (author)

1985-01-01

411

Design of a high luminosity collider for the Tau-Charm Factory  

International Nuclear Information System (INIS)

[en] Important relations between basic parameters of a high-luminosity collider are discussed. As the result, it is shown that the maximum bunch spacing is limited by the beam current to clear the threshold of the bunch lengthening. In order to solve the short bunch spacing, the crab-crossing scheme is applied to the design of a ring with 2.2 GeV, 2 x 1033 cm-2s-1 luminosity. 8 refs., 5 figs

1989-01-01

412

Dependence of the luminosity on various machine parameters and their optimization at PETRA  

Energy Technology Data Exchange (ETDEWEB)

The luminosity of a storage ring is determined by the beam currents, by the natural beam size at the interaction points and by the increase in beam height due to the beam-beam interaction. The limitation of the currents, the variation of the beam size and the minimization of the blow-up as predicted by computer simulations are discussed. Results of the optimization of the luminosity in PETRA are shown.

Piwinski, A.

1983-08-01

413

Lag-luminosity relation in gamma-ray burst X-ray flares  

CERN Multimedia

In strict analogy to prompt pulses, X-ray flares observed by Swift-XRT in long Gamma-Ray Bursts define a lag-luminosity relation: L_p,iso \\propto t_lag^{-0.95+/-0.23}. The lag-luminosity is proven to be a fundamental law extending 5 decades in time and 5 in energy. This is direct evidence that GRB X-ray flares and prompt gamma-ray pulses are produced by the same mechanism.

Margutti, R

2010-01-01

414

Improvement in luminosity, background and chamber protection with beam scrapers in the ISR  

CERN Multimedia

The Intersecting Storage Rings (ISR) are equipped with beam scrapers used for various purposes such as improving luminosity, reducing background, beam diagnostics and for protection of machine components. A description is given of the different types of scrapers and of the results in the various applications obtained during the last year. In particular, the substantial improvements in luminosity and background by scraping are described. (3 refs).

Bryant, P; Johnsen, Kjell; Laeger, H; Montague, Brian William St. Leger; Neet, D; Schneider, F W; Turner, S

1973-01-01

415

Determination of the integrated luminosity at HERA using elastic QED Compton events  

Energy Technology Data Exchange (ETDEWEB)

A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep{yields}e{gamma}p. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3%. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process.

Aaron, F.D. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Bucharest Univ. (Romania). Faculty of Physics; Alexa, C. [National Institute for Physics and Nuclear Engineering (NIPNE), Bucharest (Romania); Andreev, V. [Lebedev Physical Institute, Moscow (RU)] (and others)

2012-04-15

416

Determination of the integrated luminosity at HERA using elastic QED Compton events  

International Nuclear Information System (INIS)

A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep?e?p. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3%. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process.

2012-01-01

417

Determination of the integrated luminosity at HERA using elastic QED Compton events  

International Nuclear Information System (INIS)

[en] A measurement of the integrated luminosity at the ep collider HERA is presented, exploiting the elastic QED Compton process ep?e?p. The electron and the photon are detected in the backward calorimeter of the H1 experiment. The integrated luminosity of the data recorded in 2003 to 2007 is determined with a precision of 2.3 %. The measurement is found to be compatible with the corresponding result obtained using the Bethe-Heitler process. (orig.)

2012-01-01

418

An inference method of the luminosity spectrum in a future ee linear collider  

Science.gov (United States)

The high-luminosity ee linear collider has been studied as an energy frontier future project in high energy physics, and is expected to be a good place for the precision experiments. The high-luminosity ee linear collider no longer produces a monochromatic energy spectrum in the center of mass system, but a continuous and rather broad energy spectrum due to beamstrahlung of colliding e and e beams. Without precise knowledge of this energy spectrum alias the luminosity spectrum, the precision experiment in the linear collider should be confronted with a crucial problem. A statistical method based on new developments in information technology is examined with a view of determining the luminosity spectrum. A statistical model is formulated and a likelihood fitting is carried out to determine the luminosity spectrum by using Bhabha events. The e and e beam parameters, describing the luminosity spectrum, can be determined with an uncertainty of several percent by using 10 k Bhabha events under an ideal detector condition.

Shibata, Akihiro; Kawabata, Setsuya; Fujimoto, Junpei; Kurihara, Yoshimasa; Watanabe, Takashi

2007-02-01

419

RE-ANALYSIS OF THE RADIO LUMINOSITY FUNCTION OF GALACTIC H II REGIONS  

International Nuclear Information System (INIS)

[en] We have re-analyzed continuum and recombination lines radio data available in the literature in order to derive the luminosity function (LF) of Galactic H II regions. The study is performed by considering the first and fourth Galactic quadrants independently. We estimate the completeness level of the sample in the fourth quadrant at 5 Jy, and the one in the first quadrant at 2 Jy. We show that the two samples (fourth or first quadrant) include, as well as giant and supergiant H II regions, a significant number of subgiant sources. The LF is obtained, in each Galactic quadrant, with a generalized Schmidt's estimator using an effective volume derived from the observed spatial distribution of the considered H II regions. The re-analysis also takes advantage of recently published ancillary absorption data allowing to solve the distance ambiguity for several objects. A single power-law fit to the LFs retrieves a slope equal to -2.23 ± 0.07 (fourth quadrant) and to -1.85 ± 0.11 (first quadrant). We also find marginal evidence of a luminosity break at Lknee = 1023.45 erg s-1 Hz-1 for the LF in the fourth quadrant. We convert radio luminosities into equivalent H? and Lyman continuum luminosities to facilitate comparisons with extragalactic studies. We obtain an average total H II regions Lyman continuum luminosity of 0.89 ± 0.23 x 1053 s-1, corresponding to 30% of the total ionizing luminosity of the Galaxy.

2009-09-10

420

Measuring the Fraction of Obscured Quasars by the Infrared Luminosity of Unobscured Quasars  

CERN Multimedia

Recent work has suggested that the fraction of obscured AGN declines with increasing luminosity, but it has been difficult to quantify this trend. Here, we attempt to measure this fraction as a function of luminosity by studying the ratio of mid-infrared to intrinsic nuclear bolometric luminosity in unobscured AGN. Because the mid-infrared is created by dust reprocessing of shorter wavelength nuclear light, this ratio is a diagnostic of f_obsc, the fraction of solid angle around the nucleus covered by obscuring matter. In order to eliminate possible redshift-dependences while also achieving a large dynamic range in luminosity, we have collected archival 24 micron MIPS photometry from objects with z~1 in the Sloan Digital Sky Survey (SDSS), the Great Observatories Origins Deep Survey (GOODS) and the Cosmic Evolution Survey (COSMOS). To measure the bolometric luminosity for each object, we used archival optical data supplemented by GALEX data. We find that the mean ratio of 24 microns to bolometric luminosity d...

Treister, Ezequiel; Dullemond, Cornelis

2008-01-01

 
 
 
 
421

Fast polycrystalline CdTe detectors for bunch-by-bunch luminosity monitoring in the LHC  

CERN Multimedia

The luminosity at the four interaction points of the Large Hadron Collider (LHC) must be continuously monitored in order to provide an adequate tool for the control and optimisation of beam parameters. Polycrystalline cadmium telluride (CdTe) detectors have previously been tested, showing their high potential to fulfil the requirements of luminosity measurement in the severe environment of the LHC interaction regions. Further, the large signal yield and the fast response time should allow bunch-by-bunch measurement of the luminosity at 40 MHz with high accuracy. Four luminosity monitors with two rows of five polycrystalline CdTe detectors each have been fabricated and will be installed at both sides of the low-luminosity interaction points ALICE and LHC-b. A detector housing was specially designed to meet the mechanical constraints in the LHC. A series of elementary CdTe detectors were fabricated and tested, of which 40 were selected for the luminosity monitors. A sensitivity of 104 electrons per minimum ioni...

Brambilla, A; Jolliot, M; Bravin, E

2008-01-01

422

The radio luminosity density of star-burst galaxies and co-moving star formation rate  

CERN Multimedia

We present a new determination of the co-moving star formation density at redshifts z~<0.35 from the 1.4 GHz luminosity function of sub-mJy star-burst galaxies. Our sample, taken from Benn et al. (1993), is insensitive to dust obscuration. The shape of the Luminosity function of this sample is indistinguishable from a number of reasonable a prior models of the luminosity function. Using these shapes we calculate the modest corrections (typically ~< 20 per cent to the observed 1.4 GHz luminosity density. We find that the cosmic variance in our estimate of this luminosity density is large. We find a luminosity density in broad agreement with that from the RSA sample by Condon et al. (1987). We infer a co-moving star formation rate surprisingly similar to coeval estimates from the Canada-France Redshift Survey, in both ultraviolet and Halpha, although the later may also be affected by Cosmic variance. We conclude that the intermediate 0.05

Oliver, S; Serjeant, S; Oliver, Seb; Gruppioni, Carlotta; Serjeant, Stephen

1998-01-01

423

Luminosity functions of LMXBs in Centaurus A: globular clusters versus the field  

CERN Document Server

We study the X-ray luminosity function (XLF) of low mass X-ray binaries (LMXB) in the nearby early-type galaxy Centaurus A, concentrating primarily on two aspects of binary populations: the XLF behavior at the low luminosity limit and comparison between globular cluster and field sources. The 800 ksec exposure of the deep Chandra VLP program allows us to reach a limiting luminosity of 8e35 erg/s, about 2-3 times deeper than previous investigations. We confirm the presence of the low luminosity break in the overall LMXB XLF at log(L_X)=37.2-37.6 below which the luminosity distribution follows a constant dN/d(ln L). Separating globular cluster and field sources, we find a statistically significant difference between the two luminosity distributions with a relative underabundance of faint sources in the globular cluster population. This demonstrates that the samples are drawn from distinct parent populations and may disprove the hypothesis that the entire LMXB population in early type galaxies is created dynamic...

Voss, R; Sivakoff, G R; Kraft, R P; Jordan, A; Raychaudhuri, S; Birkinshaw, M; Brassington, N J; Croston, J H; Evans, D A; Forman, W R; Hardcastle, M J; Harris, W E; Jones, C; Juett, A M; Murray, S S; Sarazin, C L; Woodley, K A; Worrall, D M

2009-01-01

424

Low redshift AGN in the Hamburg/ESO Survey: I. The local AGN luminosity function  

CERN Multimedia

We present a determination of the local (z=0) luminosity function of optically selected type 1 (broad-line) Active Galactic Nuclei. Our primary resource is the Hamburg/ESO Survey (HES), which provides a well-defined sample of more than 300 optically bright AGN with redshifts z<0.3 and blue magnitudes B<17.5. AGN luminosities were estimated in two ways, always taking care to minimise photometric biases due to host galaxy light contamination. Firstly, we measured broad-band B_J (blue) magnitudes of the objects over small apertures of the size of the seeing disk. Secondly, we extracted H alpha and H beta broad emission line luminosities from the spectra which should be entirely free of any starlight contribution. The resulting AGN luminosity function (AGNLF) is consistent with a single power law, also when considering the effects of number density evolution within the narrow redshift range. We compared our AGNLF with the H alpha luminosity function of lower luminosity Seyfert 1 galaxies by Hao et al. (2005...

Schulze, Andreas; Husemann, Bernd

2009-01-01

425

Luminosity and surface brightness distribution of K-band galaxies from the UKIDSS Large Area Survey  

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We present luminosity and surface brightness distributions of 36,663 galaxies with K-band photometry from the UKIRT Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS), Data Release 3 and optical photometry from Data Release 5 of the Sloan Digital Sky Survey (SDSS). Various features and limitations of the new UKIDSS data are examined, such as a problem affecting Petrosian magnitudes of extended sources. Selection limits in K- and r-band magnitude, K-band surface brightness and K-band radius are included explicitly in the 1/Vmax estimation of the space density and luminosity function. The bivariate brightness distribution in K-band absolute magnitude and surface brightness is presented and found to display a clear luminosity-surface brightness correlation that flattens at high luminosity and broadens at low luminosity, consistent with similar analyses at optical wavelengths. Best fitting Schechter function parameters for the K-band luminosity function are found to be M*-5log h=-23.17 +/- 0.04, alpha=-0.8...

Smith, Anthony J; Cross, Nicholas J G

2008-01-01

426

Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity/Mass-Metallicity Relation  

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(Abridged). We present a sample of 1716 galaxies with companions within Delta v < 500 km/s, r_p < 80 kpc and stellar mass ratio 0.1 < M_1/M_2 < 10 from the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4). In agreement with p