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[Abridged] Many current and future astronomical surveys will rely on samples of strong gravitational lens systems to draw conclusions about galaxy mass distributions. We use a new strong lensing pipeline (presented in Paper I of this…

Astrophysics · Physics 2015-05-13 Rachel Mandelbaum , Glenn van de Ven , Charles R. Keeton

Previous work reported a bar signature in color-selected IRAS variable stars. Here, we estimate the source density of these variables while consistently accounting for spatial incompleteness in data using a likelihood approach. The…

Astrophysics · Physics 2007-05-23 Sergei Nikolaev , Martin D. Weinberg

Although a decade of microlensing searches towards the Large Magellanic Cloud (LMC) has detected 13-25 possible microlensing events, the nature and the location of the lenses, being either halo machos or LMC stars, remains a subject of…

Astrophysics · Physics 2009-11-07 HongSheng Zhao , Rodrigo Ibata , Geraint Lewis , Mike Irwin

We present first results from Galaxy Zoo 2, the second phase of the highly successful Galaxy Zoo project (www.galaxyzoo.org). Using a volume-limited sample of 13665 disk galaxies (0.01< z < 0.06 and M_r<-19.38), we study the fraction of…

We report idealized simulations that mimic the growth of galaxy disks embedded in responsive halos and bulges. The disks manifested an almost overwhelming tendency to form strong bars that we found very difficult to prevent. We found that…

Astrophysics of Galaxies · Physics 2017-10-11 Joel C. Berrier , J. A. Sellwood

We investigate how strong gravitational lensing can test contemporary models of massive elliptical (ME) galaxy formation, by combining a traditional decomposition of their visible stellar distribution with a lensing analysis of their mass…

The initial results of microlensing surveys toward the Galactic bulge and the LMC are puzzling. Toward the LMC, the total mass in MACHOs is of order half that required to explain the dark matter, but the estimated MACHO mass (~0.4 Msun) is…

Astrophysics · Physics 2016-01-27 Andrew Gould

We present and study the largest and the most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from years 2001--2009, with 1409 not detected before in…

The strong time-dependence of the dynamics of galactic bars yields a complex and rapidly evolving distribution of dense gas and star forming regions. Although bars mainly host regions void of any star formation activity, their extremities…

Astrophysics of Galaxies · Physics 2015-10-28 F. Renaud , F. Bournaud , E. Emsellem , O. Agertz , E. Athanassoula , F. Combes , B. Elmegreen , K. Kraljic , F. Motte , R. Teyssier

The inner ~200 pc region of the Milky Way contains a nuclear stellar disc and a nuclear star cluster that are embedded in the larger Galactic bar. These stellar systems overlap spatially, which makes it challenging to separate stars that…

Astrophysics of Galaxies · Physics 2025-07-16 A. Feldmeier-Krause , T. Veršič , G. van de Ven , E. Gallego-Cano , N. Neumayer

We investigate rapid mass supply process by nested bars in the Galaxy by numerical simulation. We simulate gas flow in the whole galaxy disk with nested bars, which are the outer bar and the inner bar, especially with highly spatial…

Astrophysics · Physics 2011-02-11 Daisuke Namekata , Asao Habe , Hidenori Matsui , Takayuki R. Saitoh

The gas distribution and dynamics in the inner Galaxy present many unknowns as the origin of the asymmetry of the longitude-velocity (lv) diagram of the Central Molecular Zone (CMZ). On the other hand, there are recent evidences in the…

Astrophysics · Physics 2009-11-13 Nemesio Rodriguez-Fernandez , Francoise Combes

In order to understand the nature of the lenses that generate microlensing events, one would like to measure their mass, distance, and velocity. Unfortunately, current microlensing experiments measure only one parameter of the events, the…

Astrophysics · Physics 2009-10-28 B. Scott Gaudi , Andrew Gould

We re-analyze constraints on the cosmological constant that can be obtained by examining the statistics of strong gravitational lensing of distant quasars by intervening galaxies, focusing on uncertainties in galaxy models (including…

Astrophysics · Physics 2007-05-23 Yu-Chung N. Cheng , Lawrence M. Krauss

Galactic bulge microlensing surveys provide a probe of Galactic structure. We present the first field-by-field comparison between microlensing observations and the Besan\c{c}on population synthesis Galactic model. Using an updated version…

Earth and Planetary Astrophysics · Physics 2016-01-27 Supachai Awiphan , Eamonn Kerins , Annie Robin

Gravitational microlensing is a unique probe of the stellar content in strong lens galaxies. Flux ratio anomalies from gravitationally lensed supernovae (glSNe), just like lensed quasars, can be used to constrain the stellar mass fractions…

Astrophysics of Galaxies · Physics 2025-04-01 Luke Weisenbach , Thomas Collett , Wolfgang Enzi , Lindsay Oldham , Ana Sainz de Murieta

For disk galaxies (spirals and irregulars), the inner circular-velocity gradient (inner steepness of the rotation curve) correlates with the central surface brightness with a slope of ~0.5. This implies that the central dynamical mass…

Astrophysics of Galaxies · Physics 2014-06-23 Federico Lelli

Many gravitationally lensed quasars exhibit flux ratio "anomalies" that cannot be explained under the hypothesis that the lensing potential is smooth on scales smaller than one kpc. Micro-lensing by stars is a natural source of granularity…

Astrophysics · Physics 2007-05-23 Paul L. Schechter , Joachim Wambsganss

With the increase in the number of observed gravitational wave (GW) signals, detecting strongly lensed GWs by galaxies has become a real possibility. Lens galaxies also contain microlenses (e.g., stars and black holes), introducing further…

Astrophysics of Galaxies · Physics 2022-10-05 Ashish Kumar Meena , Anuj Mishra , Anupreeta More , Sukanta Bose , Jasjeet Singh Bagla

We present calculations illustrating the potential of gravitational microlensing to discriminate between classical models of stellar surface brightness profiles and the recently computed ``Next Generation'' models of Hauschildt et al. These…

Astrophysics · Physics 2009-11-07 H. M. Bryce , M. A. Hendry , D. Valls-Gabaud