2974286
First microlens mass measurement: Planet photometry of EROS BLG-2000-5
We analyze PLANET photometric observations of the caustic-crossing binary lens microlensing event, EROS BLG-2000-5, and find that modeling the observed light curve requires incorporation of the microlens parallax and the binary orbital motion. The projected Einstein radius (E = 3.61 ± 0.11 AU) is derived from the measurement of the microlens parallax, and we are also able to infer the angular Einstein radius (θE = 1.38 ± 0.12 mas) from the finite source effect on the light curve, combined with an estimate of the angular size of the source given by the source position in a color-magnitude diagram. The lens mass, M = 0.612 ± 0.057 M☉, is found by combining these two quantities. This is the first time that parallax effects are detected for a caustic-crossing event and also the first time that the lens mass degeneracy has been completely broken through photometric monitoring alone. The combination of E and θE also allows us to conclude that the lens lies in the near side of the disk, within 2.6 kpc of the Sun, while the radial velocity measurement indicates that the source is a Galactic bulge giant.
55031010
Difference image analysis: extension to a spatially varying photometric scale factor and other considerations
We present a general framework for matching the point-spread function (PSF), photometric scaling and sky background between two images, a subject which is commonly referred to as difference image analysis (DIA). We introduce the new concept of a spatially varying photometric scale factor which will be important for DIA applied to wide-field imaging data in order to adapt to transparency and airmass variations across the field-of-view. Furthermore, we demonstrate how to separately control the degree of spatial variation of each kernel basis function, the photometric scale factor and the differential sky background. We discuss the common choices for kernel basis functions within our framework, and we introduce the mixed-resolution delta basis functions to address the problem of the size of the least-squares problem to be solved when using delta basis functions. We validate and demonstrate our algorithm on simulated and real data. We also describe a number of useful optimizations that may be capitalized on during the construction of the least-squares matrix and which have not been reported previously. We pay special attention to presenting a clear notation for the DIA equations which are set out in a way that will hopefully encourage developers to tackle the implementation of DIA software.
119493694
H alpha equivalent width variations across the face of a microlensed K giant in the galactic bulge
We present Very Large Telescope FORS1 spectroscopy that temporally resolves the second caustic crossing of the Galactic bulge K giant source of microlensing event EROS 2000-BLG-5, the first time this has been accomplished for several phases of a caustic transit. The similar to1 Angstrom H alpha equivalent width of the source star increases slightly as the center of the star egresses the caustic and then plummets by 30% during the final limb crossing. These changes are not seen in contemporaneous spectra of control stars in the FORS1 slit but are qualitatively consistent with expectations from stellar atmosphere models as the caustic differentially magnifies different portions of the stellar face of the target. Observations such as these in a variety of stellar lines are equivalent to atmospheric tomography and are expected to provide a direct test of stellar models.
59381191
High-Precision Limb-Darkening Measurement of a K3 Giant Using Microlensing
We obtain high-precision limb-darkening measurements in five bands (V, VE, IE, I, and H) for the K3 III (Teff = 4200 K, [Fe/H] = +0.3, log g = 2.3) source of the Galactic bulge microlensing event EROS BLG-2000-5. These measurements are inconsistent with the predictions of atmospheric models at higher than 10 σ. While the disagreement is present in all bands, it is most apparent in I, IE, and VE, in part because the data are better and in part because the intrinsic disagreement is stronger. We find that when limb-darkening profiles are normalized to have unit total flux, the I-band models for a broad range of temperatures all cross each other at a common point. The solar profile also passes through this point. However, the profile as measured by microlensing does not. We hypothesize that the models have incorporated some aspect of solar physics that is not shared by giant atmospheres.
16941683
Microlensing Constraints on the Frequency of Jupiter-Mass Companions: Analysis of 5 Years of PLANET Photometry
We analyze 5 years of PLANET photometry of microlensing events toward the Galactic bulge to search for the short-duration deviations from single-lens light curves that are indicative of the presence of planetary companions to the primary microlenses. Using strict event-selection criteria, we construct a well-defined sample of 43 intensively monitored events. We search for planetary perturbations in these events over a densely sampled region of parameter space spanning two decades in mass ratio and projected separation, but find no viable planetary candidates. By combining the detection efficiencies of the events, we find that, at 95% confidence, less than 25% of our primary lenses have companions with mass ratio q = 10-2 and separations in the lensing zone, [0.6-1.6]θE, where θE is the Einstein ring radius. Using a model of the mass, velocity, and spatial distribution of bulge lenses, we infer that the majority of our lenses are likely M dwarfs in the Galactic bulge. We conclude that less than 33% of M dwarfs in the Galactic bulge have companions with mass mp = MJ between 1.5 and 4 AU, and less than 45% have companions with mp = 3MJ between 1 and 7 AU, the first significant limits on planetary companions to M dwarfs. We consider the effects of the finite size of the source stars and changing our detection criterion, but find that these do not alter our conclusions substantially.
118468268
The PLANET microlensing campaign: Implications for planets around galactic disk and bulge stars
With round-the-clock monitoring of galactic bulge microlensing events, the PLANET experiment constrains the abundance and can yield the discovery of planets down to the mass of earth around galactic disk and bulge stars. Data taken until 1999 imply that less than 1/3 of bulge M-dwarfs are surrounded by jupiter-mass companions at orbital radii between 1 and 4 AU. The current rate of microlensing alerts allows 15-25 jupiters and 1-3 earths to be probed per year.
119272831
Central Exclusive Particle Production at High Energy Hadron Colliders
We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A +B ! A +X +B, where X is a fully specied system of particles that is well separated in rapidity from the outgoing beam particles. We focus on the case where the colliding particles are strongly interacting and mainly they will be protons (or antiprotons) as at the ISR, Sp pS, Tevatron and LHC. The data are surveyed and placed within the context of theoretical developments.
119164045
Central exclusive production at the Tevatron
The Collider Detector at Fermilab, CDF, observed for the first time in hadron–hadron collisions photon–photon (γ + γ → e+e-, μ+μ-) and photon–pomeron (γ + ℙ → J/ψ, ψ(2S)) interactions, as well as by double pomeron exchange, ℙ + ℙ or DPE. Exclusive π+π- production was also measured at and 1960 GeV; resonance structures are discussed.
122579699
Evidence for a directional dependence of Bose-Einstein correlations at the CERN intersecting storage rings
Abstract In pp and pp collisions at the CERN Intersecting Storage Rings, a directional dependence of the size of the pion-emitting region is observed using Bose-Einstein interference between identical charged pions. The data reveal a substantially larger dimension in the direction parallel to the beam axis than in the transverse direction, indicating a prolate shape of the emission region. For αα interactions, the data are consistent with a spherical shape.
121849522
The design and calibration of precision drift chambers for use in a gluonium search experiment at the CERN ISR
We describe the design, construction and calibration of a set of high precision drift chambers. The precise coordinate (σ ∼ 120 μm) is determined by drift time measurement, with the orthogonal coordinate given by the charge division method (σ∼1.2 mm). The chambers have been calibrated using a well-defined laser beam. Their use within a gluonium search experiment at the CERN ISR is also described.
9678988
Double Pomeron Physics at the LHC
I discuss central exclusive production, also known as Double Pomeron Exchange, DIPE, from the ISR through the Tevatron to the LHC. There I emphasize the interest of exclusive Higgs and W+W−/ZZ production.