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3 results on '"MICROLENSING OPTICAL DEPTH"'

1. VVV survey microlensing: Candidate events with a source in the far disk

Author

María Gabriela Navarro, Rodrigo Contreras Ramos, and Dante Minniti

Subjects
Physics, Gravitational lens, Astrophysics - Solar and Stellar Astrophysics, Space and Planetary Science, Bulge, Astrophysics of Galaxies (astro-ph.GA), Galaxy structure, Galactic bulge, Gravitational lensing, Gravitational microlensing, Interstellar extinction, Near infrared astronomy, Surveys, Microlensing event rate, Microlensing optical depth, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrophysics - Astrophysics of Galaxies, Solar and Stellar Astrophysics (astro-ph.SR)
Abstract

The VVV microlensing search has recently surveyed the region of the Galactic plane at b=0 within -10.00 < l < 10.44 deg. in the near-infrared (IR), discovering hundreds of microlensing events. In this paper we explore the microlensing events with background sources that might be located in the far disk of the Galaxy, beyond the bulge. We discuss the possible configurations for the microlensing lenses and sources located at different places within the Galactic plane. Then we search for these events using the local red clump centroids of the VVV near-IR color-magnitude diagrams. According to the estimated distances and proper motions, N=20 events may have sources located in the far disk. The candidates for far-disk sources show on average longer timescales (tE= 49.3 +- 7.9 days) than the mean of the timescale distribution for the bulge red clump sources (tE= 36.4 +- 1.1 days). We conclude that the population of microlensing events in the region -10.00 < l < 10.44, -0.46 < b < 0.65 deg. contains a non-negligible number of events with candidate far-disk sources (~ 11 %). Our results are relevant in view of the future microlensing plans with the Roman Space Telescope (formerly WFIRST) in the near-IR., 9 pages, 5 figures and 2 tables. Accepted for publication in ApJ

Published
2020

2. The OGLE-II event sc5_2859 : a Classical Nova outburst?

Author

C. Afonso, J. F. Glicenstein, A. Gould, M. C. Smith, R. M. Wagner, J. N. Albert, J. Andersen, R. Ansari, É. Aubourg, P. Bareyre, J. P. Beaulieu, G. Blanc, X. Charlot, C. Coutures, R. Ferlet, P. Fouqué, B. Goldman, D. Graff, M. Gros, J. Haissinski, C. Hamadache, J. de Kat, L. LeGuillou, É. Lesquoy, C. Loup, C. Magneville, J. B. Marquette, É. Maurice, A. Maury, A. Milsztajn, M. Moniez, N. Palanque-Delabrouille, O. Perdereau, L. Prévot, Y. R. Rahal, J. Rich, M. Spiro, P. Tisserand, A. Vidal-Madjar, L. Vigroux, S. Zylberajch, Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de l'Accélérateur Linéaire (LAL), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), AstroParticule et Cosmologie (APC (UMR_7164)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Institut d'Astrophysique de Paris (IAP), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Astrophysique de Marseille (LAM), Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS), Services communs OMP (UMS 831), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France -Centre National de la Recherche Scientifique (CNRS), EROS, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Météo France-Centre National d'Études Spatiales [Toulouse] (CNES)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS), Astronomy, Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Observatoire de Paris, PSL Research University (PSL)-PSL Research University (PSL)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Aix Marseille Université (AMU)-Centre National d'Études Spatiales [Toulouse] (CNES), Services communs OMP - UMS 831 (UMS 831), Centre National de la Recherche Scientifique (CNRS)-Observatoire Midi-Pyrénées (OMP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales [Toulouse] (CNES)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées

Subjects
stars : novae, cataclysmic variables, MACHO PROJECT, 010504 meteorology & atmospheric sciences, Event (relativity), GRAVITATIONAL LENSING EXPERIMENT, Gravitational lensing, FOS: Physical sciences, Astrophysics, Gravitational microlensing, 01 natural sciences, Galaxy : stellar contents, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], 0103 physical sciences, Galaxy:stellar contents, Emission spectrum, 010303 astronomy & astrophysics, BLACK-HOLES, 0105 earth and related environmental sciences, Physics, cataclysmic variables, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], MICROLENSING OPTICAL DEPTH, Astrophysics (astro-ph), Astronomy and Astrophysics, Light curve, DIFFERENCE IMAGE-ANALYSIS, CATALOG, Nova (rocket), GALACTIC BULGE FIELDS, Space and Planetary Science, stars : novae, novæ
Abstract

The OGLE-II event sc5_2859 was previously identified as the third longest microlensing event ever observed. Additional photometric observations from the EROS (Experience de Recherche d'Objets Sombres) survey and spectroscopic observations of the candidate star are used to test the microlensing hypothesis.The combined OGLE and EROS data provide a high quality coverage of the light curve. The colour of the sc5_2859 event is seen to change with time. A spectrum taken in 2003 exhibits a strong Halpha emission line. The additionnal data show that the OGLE-II sc5_2859 event is actually a classical nova outburst., Comment: Accepted for publication in Astronomy and Astrophysics

Published
2006
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3. Mapping stellar kinematics across the Galactic bar: HST measurements of proper motions in 35 fields

Author

Matthew Smith, P. R. Wozniak, Takahiro Sumi, Szymon Kozłowski, W. T. Vestrand, L. Wyrzykowski, Shude Mao, and Kapteyn Astronomical Institute

Subjects
Stellar kinematics, Proper motion, gravitational lensing, Galaxy : kinematics and dynamics, GRAVITATIONAL LENSING EXPERIMENT, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Astrophysics, Bulge, SYSTEMS, Galaxy : bulge, Astrophysics::Galaxy Astrophysics, Physics, Galactic Center, MICROLENSING OPTICAL DEPTH, Astrophysics (astro-ph), Sigma, Astronomy and Astrophysics, Galaxy : disc, Galactic plane, BULGE FIELDS, DIFFERENCE IMAGE-ANALYSIS, GALAXY, MODEL, Stars, Mean motion, Space and Planetary Science, PROJECT
Abstract

We present a proper motion mini-survey of 35 fields in the vicinity of Baade window, (l, b) = (1 deg, -4 deg), sampling roughly a 5 x 2.5 deg region of the Galactic bar. Our second epoch observations collected with the ACS/HRC instrument on board the Hubble Space Telescope were combined with the archival WFPC2/PC images. The resulting time baselines are in the range of 4 - 8 years. Precise proper motions of 15,863 stars were determined in the reference frame defined by the mean motion of stars with magnitudes between I_F814W = 16.5 - 21.5 along the line of sight. We clearly detect small gradients in proper motion dispersions (sigma_l, sigma_b) ~ (3.0, 2.5) mas/yr, and in the amount of anisotropy (sigma_l/sigma_b ~ 1.2). Both the longitude dispersion sigma_l and its ratio to the vertical motion sigma_b increase toward the Galactic plane. The decline of the anisotropy ratio sigma_l/sigma_b toward the minor axis of the bulge is mostly due to increasing sigma_b. We also find, for the first time, a significant negative covariance term in the transverse velocity field sigma_lb/(sigma_l*sigma_b) ~ -0.10. Our results extend by a factor of ~15 the number of the Galactic bar fields with good proper motion dispersions., Comment: 11 pages, 7 figures, 3 tables, accepted for publication in MNRAS

Published
2006
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