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First Space-Based Microlens Parallax Measurement: Spitzer Observations of OGLE-2005-SMC-001
Subo Dong, A. Udalski, A. Gould +20
We combine Spitzer and ground-based observations to measure the microlens parallax of OGLE-2005-SMC-001, the first such space-based determination since S. Refsdal proposed the idea…
Removing the Microlensing Blending-Parallax Degeneracy Using Source Variability
R. J. Assef, A. Gould, the EROS-2 +2
Microlensing event MACHO 97-SMC-1 is one of the rare microlensing events for which the source is a variable star, simply because most variable stars are systematically eliminated f…
Fitting Photometry of Blended Microlensing Events
Christian L. Thomas, Kim Griest
We reexamine the usefulness of fitting blended lightcurve models to microlensing photometric data. We find agreement with previous workers (e.g. Wozniak & Paczynski) that this is a…
Contamination in the MACHO dataset and the puzzle of LMC Microlensing
Kim Griest, Christian L. Thomas
In a recent series of three papers, Belokurov, Evans, and Le Du, and Evans and Belokurov, reanalysed the MACHO collaboration data and gave alternative sets of microlensing events a…
Galactic Bulge Microlensing Events from the MACHO Collaboration
C. L. Thomas, K. Griest, P. Popowski +21
We present a catalog of 450 high signal-to-noise microlensing events observed by the MACHO collaboration between 1993 and 1999. The events are distributed throughout our fields and…
Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey
P. Popowski, K. Griest, C. L. Thomas +20
Using 7 years of MACHO survey data, we present a new determination of the optical depth to microlensing towards the Galactic bulge. We select the sample of 62 microlensing events (…
The Microlensing Planet Finder: Completing the Census of Extrasolar Planets in the Milky Way
D. P. Bennett, I. Bond, E. Cheng +21
The Microlensing Planet Finder (MPF) is a proposed Discovery mission that will complete the first census of extrasolar planets with sensitivity to planets like those in our own sol…
The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance
C. Alcock, D. R. Alves, T. S. Axelrod +21
Fourier coefficents have been derived for the and light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC. The and coef…
The MACHO Project Large Magellanic Cloud variable star inventory. XI. Frequency analysis of the fundamental mode RR Lyrae stars
C. Alcock, D. R. Alves, A. Becker +20
We have frequency analyzed 6391 variables classified earlier as fundamental mode RR Lyrae (RR0) stars in the MACHO database on the Large Magellanic Cloud (LMC). The overwhelming ma…
Recent Microlensing Results from the MACHO Project
P. Popowski, C. A. Nelson, D. P. Bennett +19
We describe a few recent microlensing results from the MACHO Collaboration. The aim of the MACHO Project was the identification and quantitative description of dark and luminous ma…
Variability-Selected Quasars in MACHO Project Magellanic Cloud Fields
M. Geha, C. Alcock, R. A. Allsman +22
We present 47 spectroscopically-confirmed quasars discovered behind the Magellanic Clouds identified via photometric variability in the MACHO database. Thirty-eight quasars lie beh…
The Galactic Exoplanet Survey Telescope (GEST)
D. P. Bennett, J. Bally, I. Bond +22
The Galactic Exoplanet Survey Telescope (GEST) will observe a 2 square degree field in the Galactic bulge to search for extra-solar planets using a gravitational lensing technique.…
MACHO Project Analysis of the Galactic Bulge Microlensing Events with Clump Giants as Sources
P. Popowski, T. Vandehei, K. Griest +19
We present preliminary results of the analysis of 5 years of MACHO data on the Galactic bulge microlensing events with clump giants as sources. This class of events allows one to o…
Toward a Possible Solution to the Cosmic Coincidence Problem
Kim Griest
It is a mystery why the density of matter and the density of vacuum energy are nearly equal today when they scale so differently during the expansion of the Universe. We suggest a…
The MACHO Project LMC Variable Star Inventory: XII. Three Cepheid Variables in Eclipsing Binaries
C. Alcock, R. A. Allsman, D. R. Alves +22
We present a method for solving the lightcurve of an eclipsing binary system which contains a Cepheid variable as one of its components as well as the solutions for three eclipsing…
Gravitational Microlensing Events Due to Stellar Mass Black Holes
D. P. Bennett, A. C. Becker, J. L. Quinn +28
We present an analysis of the longest timescale microlensing events discovered by the MACHO Collaboration during a 7 year survey of the Galactic bulge. We find 6 events that exhibi…
The difficulty in using orphan afterglows to measure gamma-ray burst beaming
Neal Dalal, Kim Griest, Jason Pruet
If gamma-ray burst (GRB) emission is strongly collimated then GRBs occur throughout the Universe at a rate much higher than is detected. Since the emission from the optical aftergl…
The MACHO Project LMC Variable Star Inventory: X. The R Coronae Borealis Stars
C. Alcock, R. A. Allsman, D. R. Alves +26
We report the discovery of eight new R Coronae Borealis (RCB) stars in the Large Magellanic Cloud (LMC) using the MACHO project photometry database. The discovery of these new star…
Astrometric imaging of crowded stellar fields with only two SIM pointings
Neal Dalal, Kim Griest
The Space Interferometry Mission (SIM) will observe sources in crowded fields. Recent work has shown that source crowding can induce significant positional errors in SIM's astromet…
Mass-Losing Semiregular Variable Stars in Baade's Windows
C. Alard, J. Blommaert, C. Cesarsky +38
By cross-correlating the results of two recent large-scale surveys, the general properties of a well defined sample of semi-regular variable stars have been determined. ISOGAL mid-…
MACHO 96-LMC-2: Lensing of a Binary Source in the LMC and Constraints on the Lensing Object
C. Alcock, R. A. Allsman, D. R. Alves +21
We present photometry and analysis of the microlensing alert MACHO 96-LMC-2. The ~3% photometry provided by the Global Microlensing Alert Network follow--up effort reveals a period…
MACHO Project Limits on Black Hole Dark Matter in the 1-30 Solar Mass Range
The Macho collaboration, C. Alcock, R. A. Allsman +22
We report on a search for long duration microlensing events towards the Large Magellanic Cloud. We find none, and therefore put limits on the contribution of high mass objects to t…
A 421 d Activity Cycle in the BeX Recurrent Transient A0538-66 from MACHO monitoring
C. Alcock, R. A. Allsman, D. R. Alves +23
We present a ~ 5-yr optical light curve of the recurrent Be/X-ray transient A0538-66 obtained as a by-product of the MACHO Project. These data reveal both a long-term modulation at…
Black Holes Must Die
Neal Dalal, Kim Griest
In light of recent evidence suggesting a nonzero present-day cosmological constant, Adams, Mbonye, & Laughlin (1999) have considered the evolution of black holes in the presence of…