Gravitational microlensing of the Galactic bulge stars

Kiraga, M.; Paczyński, B.

doi:10.1086/187448

Cited by 186 publications

(244 citation statements)

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“…Theoretical estimates were increased by Kiraga & Paczy nski (1994) to somewhat above 10 6 when the importance of self-lensing by the bulge was recognized, and increased even more when the importance of the galactic bar was noticed . Subsequent calculations, using the best available bar model, gave the optical depth of 2 10 6 (Zhao et al 1995), within one standard deviation of the observational results.…”

Section: Past and Presentmentioning

confidence: 95%

Gravitational Microlensing, the Distance Scale, and the Ages

Paczyński

1996

Astrophysical Applications of Gravitational Lensing

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Abstract.A high optical depth to gravitational microlensing towards the galactic bulge is consistent with current models of the galactic bar. The low optical depth towards the LMC can probably be accounted for by the ordinary stars in our galaxy and in the LMC itself. No conclusive evidence is available yet for the presence or absence of a large number of brown dwarfs or other non-stellar compact objects which might account for the dark matter. There is little doubt that the amount of mass in objects in the range 10 8 M=M 10 6 will be determined within the next few years with the continuing and expanding searches.Billions of photometric measurements generated by the microlensing searches have lead to the discovery of 10 5 variable stars. In particular, a number of detached eclipsing binaries were discovered in the galactic bulge, in the LMC, and in the globular cluster Omega Centauri. The followup observations of these binaries will allow the determination of accurate distances to all these objects, as well as robust age determination of globular clusters.

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Section: Past and Presentmentioning

confidence: 95%

Gravitational Microlensing, the Distance Scale, and the Ages

Paczyński

1996

Astrophysical Applications of Gravitational Lensing

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“…With only about one in a million monitored stars being significantly brightened by the gravitational field of a foreground star (Kiraga & Paczyński 1994), the OGLE (Optical Gravitational Lensing Experiment) and MOA (Microlensing Observations in Astrophysics) surveys monitor more than 100 million stars on a daily basis, which results in 700-1000 microlensing events per year being alerted online while they are in progress (Udalski et al 1992;Muraki et al 1999;Bond et al 2001;Udalski 2003). Their sampling is however insufficient for detecting planets with masses significantly below that of Jupiter (Snodgrass, Tsapras & Horne 2004).…”

Section: Microlensing Observation Campaignsmentioning

confidence: 99%

ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search): A possible expert‐system based cooperative effort to hunt for planets of Earth mass and below

et al. 2008

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The technique of gravitational microlensing is currently unique in its ability to provide a sample of terrestrial exoplanets around both Galactic disk and bulge stars, allowing to measure their abundance and determine their distribution with respect to mass and orbital separation. Thus, valuable information for testing models of planet formation and orbital migration is gathered, constituting an important piece in the puzzle for the existence of life forms throughout the Universe. In order to achieve these goals in reasonable time, a well-coordinated effort involving a network of either 2m or 4×1m telescopes at each site is required. It could lead to the first detection of an Earth-mass planet outside the Solar system, and even planets less massive than Earth could be discovered. From April 2008, ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) is planned to provide a platform for a three-step strategy of survey, follow-up, and anomaly monitoring. As an expert system embedded in eSTAR (e-Science Telescopes for Astronomical Research), ARTEMiS will give advice for follow-up based on a priority algorithm that selects targets to be observed in order to maximize the expected number of planet detections, and will also alert on deviations from ordinary microlensing light curves by means of the SIGNALMEN anomaly detector. While the use of the VOEvent (Virtual Observatory Event) protocol allows a direct interaction with the telescopes that are part of the HTN (Heterogeneous Telescope Networks) consortium, additional interfaces provide means of communication with all existing microlensing campaigns that rely on human observers. The success of discovering a planet by microlensing critically depends on the availability of a telescope in a suitable location at the right time, which can mean within 10 min. To encourage follow-up observations, microlensing campaigns are therefore releasing photometric data in real time. On ongoing planetary anomalies, world-wide efforts are being undertaken to make sure that sufficient data are obtained, since there is no second chance. Real-time modelling offers the opportunity of live discovery of extra-solar planets, thereby providing "Science live to your home".

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“…By concentrating on the inner Galactic Bulge (Galactic Centre) region we maximise the number density of bright red giant sources to be lensed by faint brown dwarfs also in the Bulge (bulge-bulge lensing, see Kiraga & Paczynski 1994). Red giants have an absolute K-magnitude close to -3 mag, thus for a distance modulus m -M == 14.5 mag to the Galactic Centre and an extinction of AK == 3 mag (corresponding to A v == 30 mag) the apparent magnitude of red giants near the Galactic Centre becomes K == 14.5 mag.…”

Section: Bulge Giants Lensed By Bulge Brown Dwarfsmentioning

confidence: 99%

Microlensing by Free-Floating Brown Dwarfs

Zinnecker¹

2003

Symp. - Int. Astron. Union

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Abstract. We propose a near-infrared microlensing survey of the central 2 degree field of the Galactic Center, in an attempt to estimate the surface density and mass distribution of distant free-floating brown dwarfs in the bulge and in the disk, acting as lenses of bright stars towards the Galactic Center. We estimate the probability (optical depth) of microlensing events to be 10-7 and the typical timescale (full-width) of the amplification lightcurve to be about 1 week. The necessary wide-field NIR survey technology should soon be available on UKIRT, CFHT, and with VISTA at ESO jParanal.

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Gravitational microlensing of the Galactic bulge stars

Cited by 186 publications

References 0 publications

Gravitational Microlensing, the Distance Scale, and the Ages

Gravitational Microlensing, the Distance Scale, and the Ages

ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search): A possible expert‐system based cooperative effort to hunt for planets of Earth mass and below

Microlensing by Free-Floating Brown Dwarfs

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