Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal?
The observed distribution of a blending-corrected sample of Einstein ring crossing times, tE, for microlensing events toward the galactic bulge/bar are analyzed. An inspection of the distribution of crossing times suggests that it may be bimodal, indicating that two populations of lenses could be re...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
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The Korean Space Science Society
2012-06-01
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| Series: | Journal of Astronomy and Space Sciences |
| Subjects: | |
| Online Access: | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2012/v29n2/OJOOBS_2012_v29n2_191.pdf |
| _version_ | 1797369700675485696 |
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| author | Mitchell F. Struble Thulsi Wickramasinghe |
| author_facet | Mitchell F. Struble Thulsi Wickramasinghe |
| author_sort | Mitchell F. Struble |
| collection | DOAJ |
| description | The observed distribution of a blending-corrected sample of Einstein ring crossing times, tE, for microlensing events toward the galactic bulge/bar are analyzed. An inspection of the distribution of crossing times suggests that it may be bimodal, indicating that two populations of lenses could be responsible for observed microlensing events. Given the possibility that microlensing in this direction can be due to the two most common classes of stars, main-sequence and white dwarf, we analyze and show via Monte Carlo simulations that the observed bimodality of tE can be derived from their accepted mass functions, and the density distributions of both stellar populations in the galactic disk and bulge/bar, with a transverse velocity distribution that is consistent with the density distribution. Kolmogorov-Smirnov (KS) one sample tests shows that a white dwarf population of about 25% of all stars in the galaxy agrees well with the observed bimodality with a KS significance level greater than 97%. This is an expanded and updated version of a previous investigation (Wickramasinghe, Neusima, & Struble, in Mao 2008). A power-point version of the talk, with introductory figures, is found at: https://sites.google.com/site/rhkochconference/agenda-1/program. |
| first_indexed | 2024-03-08T17:50:38Z |
| format | Article |
| id | doaj.art-f36204985f0f4722963fb29eb7944564 |
| institution | Directory Open Access Journal |
| issn | 2093-5587 2093-1409 |
| language | English |
| last_indexed | 2024-03-08T17:50:38Z |
| publishDate | 2012-06-01 |
| publisher | The Korean Space Science Society |
| record_format | Article |
| series | Journal of Astronomy and Space Sciences |
| spelling | doaj.art-f36204985f0f4722963fb29eb79445642024-01-02T09:04:43ZengThe Korean Space Science SocietyJournal of Astronomy and Space Sciences2093-55872093-14092012-06-0129219119410.5140/JASS.2012.29.2.191Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal?Mitchell F. Struble0Thulsi Wickramasinghe1Depatment of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USAFulbright Fellow at the University of Peradeniya, Sri LankaThe observed distribution of a blending-corrected sample of Einstein ring crossing times, tE, for microlensing events toward the galactic bulge/bar are analyzed. An inspection of the distribution of crossing times suggests that it may be bimodal, indicating that two populations of lenses could be responsible for observed microlensing events. Given the possibility that microlensing in this direction can be due to the two most common classes of stars, main-sequence and white dwarf, we analyze and show via Monte Carlo simulations that the observed bimodality of tE can be derived from their accepted mass functions, and the density distributions of both stellar populations in the galactic disk and bulge/bar, with a transverse velocity distribution that is consistent with the density distribution. Kolmogorov-Smirnov (KS) one sample tests shows that a white dwarf population of about 25% of all stars in the galaxy agrees well with the observed bimodality with a KS significance level greater than 97%. This is an expanded and updated version of a previous investigation (Wickramasinghe, Neusima, & Struble, in Mao 2008). A power-point version of the talk, with introductory figures, is found at: https://sites.google.com/site/rhkochconference/agenda-1/program.http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2012/v29n2/OJOOBS_2012_v29n2_191.pdfgravitational microlensing: einstein crossing timesgalaxy: bar/bulge |
| spellingShingle | Mitchell F. Struble Thulsi Wickramasinghe Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? Journal of Astronomy and Space Sciences gravitational microlensing: einstein crossing times galaxy: bar/bulge |
| title | Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? |
| title_full | Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? |
| title_fullStr | Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? |
| title_full_unstemmed | Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? |
| title_short | Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal? |
| title_sort | are the distribution of einstein crossing times of galactic microlensing events bimodal |
| topic | gravitational microlensing: einstein crossing times galaxy: bar/bulge |
| url | http://ocean.kisti.re.kr/downfile/volume/kosss/OJOOBS/2012/v29n2/OJOOBS_2012_v29n2_191.pdf |
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