- ID:
- ivo://CDS.VizieR/J/ApJ/889/56
- Title:
- VVV survey microlensing events; -3.7<b{<}-3.9{deg}
- Short Name:
- J/ApJ/889/56
- Date:
- 17 Jan 2022 11:50:08
- Publisher:
- CDS
- Description:
- We search for microlensing events in fields along the Galactic minor axis, ranging from the Galactic center to -3.7{deg}<b<3.9{deg} using the VISTA Variables in the Via Lactea (VVV) survey near-IR photometry. The new search is made across VVV tiles b291, b305, b319, b347, b361, and b375, covering a total area of about 11.5deg^2^. We find a total of N=238 new microlensing events in this new area, N=74, which are classified as bulge red clump (RC) giant sources. Combining them with N=122 events that we had previously reported in the Galactic center (VVV tile b333), allows us to study the latitude distribution of the microlensing events reaching the Galactic plane at b=00 for the first time. We find a very strong dependence of the number of microlensing events with Galactic latitude, a number that increases rapidly toward the Galactic center by one order of magnitude from |b|=2{deg} to b=0{deg} with a much steeper gradient than with Galactic longitude. The microlensing event population shows a flattened distribution (axial ratio b/a~1.5). The final sample shows a shorter mean timescale distribution than the Galactic plane sample for both the complete population and RC stars.
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- ID:
- ivo://CDS.VizieR/J/ApJ/893/65
- Title:
- VVV Survey microlensing events in the Gal. Bulge
- Short Name:
- J/ApJ/893/65
- Date:
- 19 Jan 2022 11:43:07
- Publisher:
- CDS
- Description:
- We search for microlensing events in the zero-latitude area of the Galactic Bulge using the VVV Survey near-IR data. We have discovered a total sample of N=630 events within an area covering 20.68deg^2^ between the years 2010 and 2015. In this paper, we describe the search and present the data for the final sample, including near-IR magnitudes, colors, and proper motions, as well as the standard microlensing parameters. We use the near-IR color-magnitude and color-color diagrams to select NRC=290 events with red-clump sources to analyze the extinction properties of the sample in the central region of the Galactic plane. The timescale distribution and its dependence in the longitude axis is presented. The mean timescale decreases as we approach the Galactic minor axis (b=0{deg}). Finally, we give examples of special microlensing events, such as binaries, short-timescale events, and events with a strong parallax effect.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/2232
- Title:
- Weak lensing of SDSS galaxy clusters. III.
- Short Name:
- J/ApJ/703/2232
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of the excess mass-to-light ratio (M/L) measured around MaxBCG galaxy clusters observed in the Sloan Digital Sky Survey. This red-sequence cluster sample includes objects from small groups with M_200_~5x10^12^/hM_{sun}_ to clusters with M_200_~10^15^/hM_{sun}_. Using cross-correlation weak lensing, we measure the excess mass density profile above the universal mean {Delta}{rho}(r)={rho}(r)-{bar}{rho} for clusters in bins of richness and optical luminosity. We also measure the excess luminosity density {Delta}l(r)=l(r)-{bar}l measured in the z=0.25 i band. For both mass and light, we de-project the profiles to produce three-dimensional mass and light profiles over scales from 25h^-1^kpc to 22h^-1^Mpc. From these profiles we calculate the cumulative excess mass {Delta}M(r) and excess light {Delta}L(r) as a function of separation from the BCG.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A135
- Title:
- 20 years of photometric microlensing
- Short Name:
- J/A+A/617/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gaia DR2 offers unparalleled precision on stars' parallaxes and proper motions. This allows the prediction of microlensing events for which the lens stars (and any planets they possess) are nearby and may be well studied and characterised. We identify a number of potential microlensing events that will occur before the year 2035.5, 20 years from the Gaia DR2 reference epoch. We query Gaia DR2 for potential lenses within 100pc, extract parallaxes and proper motions of the lenses and background sources, and identify potential lensing events. We estimate the lens masses from Priam effective temperatures, and use these to calculate peak magnifications and the size of the Einstein radii relative to the lens stars' habitable zones. We identify 7 future events with a probability >10% of an alignment within one Einstein radius. Of particular interest is DR2 5918299904067162240 (WISE J175839.20-583931.6), magnitude G=14.9, which will lens a G=13.9 background star in early 2030, with a median 23% net magnification. Other pairs are typically fainter, hampering characterisation of the lens (if the lens is faint) or the ability to accurately measure the magnification (if the source is much fainter than the lens). Of timely interest is DR2 4116504399886241792 (2MASS J17392440-2327071), which will lens a background star in July 2020, albeit with weak net magnification (0.03%). Median magnifications for the other 5 high-probability events range from 0.3% to 5.3%. The Einstein radii for these lenses are 1-10 times the radius of the habitable zone, allowing these lensing events to pick out cold planets around the ice line, and filling a gap between transit and current microlensing detections of planets around very low-mass stars. We provide a catalogue of the predicted events to aid future characterisation efforts. Current limitations include a lack of many high-proper motion objects in Gaia DR2 and often large uncertainties on the proper motions of the background sources (or only 2-parameter solutions). Both of these deficiencies will be rectified with Gaia DR3 in 2020. Further characterisation of the lenses is also warranted to better constrain their masses and predict the photometric magnifications.
