J/ApJ/889/56 VVV survey microlensing events; -3.7<b<-3.9° (Navarro+, 2020)
VVV survey microlensing: the Galactic latitude dependence.
Navarro M.G., Minniti D., Pullen J., Ramos R.C.
<Astrophys. J., 889, 56 (2020)>
=2020ApJ...889...56N 2020ApJ...889...56N
ADC_Keywords: Galactic center; Gravitational lensing; Photometry, infrared
Keywords: Galactic bulge ; Milky Way Galaxy physics ; Galaxy structure ;
Gravitational microlensing ; Gravitational lensing ; Galactic center
Abstract:
We search for microlensing events in fields along the Galactic minor
axis, ranging from the Galactic center to -3.7°<b<3.9° 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 11.5deg2. 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° to
b=0° 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.
Description:
The first VISTA Variables in the Via Lactea Survey (VVV) microlensing
events in the Galactic center region were published by
Navarro+ (2017ApJ...851L..13N 2017ApJ...851L..13N). In this paper we complement the
previous studies by dealing with the latitude dependence of
microlensing, by analyzing six more VVV tiles. See Sections 1 and 2.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 102 238 VVV Survey first quality microlensing events
--------------------------------------------------------------------------------
See also:
II/337 : VISTA Variables in the Via Lactea Survey DR1 (Saito+, 2012)
II/364 : VIRAC. The VVV Infrared Astrometric Catalogue (Smith+, 2019)
J/PASP/121/1180 : Color panorama image of the Milky Way (Mellinger+, 2009)
J/ApJ/778/150 : MOA-II microlensing events toward the Bulge (Sumi+, 2013)
J/MNRAS/457/4089 : Frequency of snowline-region planets (Shvartzvald+, 2016)
J/A+A/609/A116 : Low extinction TGAS HR Catalogue (Ruiz-Dern+, 2018)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Tile [291/375] Tile number (1)
5- 10 I6 --- ID [1531/106680] Identifier
12- 19 F8.5 deg GLON [-1.24/0.26] Galactic longitude (2)
21- 28 F8.5 deg GLAT [-3.61/3.9] Galactic latitude (2)
30- 34 F5.2 mag Ksmag [10.96/17.46] Apparent Ks band magnitude (3)
36- 39 F4.2 mag J-K [0.79/9] The (J-K) color index (3)
41- 44 F4.2 mag Amp [0.13/2.9] Amplitude
46- 49 F4.2 --- u0 [0/1.5] Minimum impact parameter
in Einstein radii
51- 54 F4.2 --- e_u0 [0/2] One standard deviation error in mu0
56- 63 F8.2 d MJD Modified Julian Date of event maximum
magnification
65- 70 F6.2 d e_MJD [0.02/136] One standard deviation error in MJD
72- 77 F6.2 d tE [3.59/750] Event timescale
79- 86 F8.2 d e_tE [0.4/11456] One standard deviation error in tE
88- 91 F4.2 --- fbl [0/1] Blending parameter
93- 98 F6.2 --- e_fbl [0.01/102] One standard deviation error in fbl
100-102 A3 --- OGLE "DET" indicates an OGLE detection
--------------------------------------------------------------------------------
Note (1): Tile as follows:
-----------------------------------------------------------------------------
Tile GLON GLAT N* N*c NRC NRCc Nev Nevc NevRC NevRCc
-----------------------------------------------------------------------------
b291 359.50054 -3.13672 53.7e5 65.2e5 3.8e5 4.7e5 22 26 5 6
b305 359.49334 -2.04452 49.2e5 59.2e5 6.3e5 7.6e5 34 40 10 12
b319 359.48996 -0.95233 48.9e5 77.8e5 10.8e5 17.3e5 59 93 18 28
b333 359.48985 +0.13988 60.6e5 144.5e5 13.7e5 32.7e5 122 290 38 90
b347 359.49322 +1.23206 53.8e5 64.4e5 9.4e5 11.2e5 56 66 25 29
b361 359.50024 +2.32421 58.4e5 71.3e5 5.8e5 7.0e5 42 51 14 17
b375 359.51046 +3.41635 58.3e5 67.8e5 3.4e5 3.9e5 25 29 2 2
-----------------------------------------------------------------------------
Number of sources (N*) and red clump sources (NRC) analyzed,
Number of events (Nev) for the whole sample and the RC subsample (NevRC)
Both raw and corrected ("c") by completeness.
-----------------------------------------------------------------------------
Note (2): Typical positional errors are 0.1" (Smith+ 2018MNRAS.474.1826S 2018MNRAS.474.1826S ;
Cat. II/364)
Note (3): Typical photometric errors are 0.01mag in Ksmag, and 0.03mag
in J-K (Saito+ 2012A&A...537A.107S 2012A&A...537A.107S -- Cat. II/337 and
Contreras Ramos+ 2017A&A...608..140C 2017A&A...608..140C and
Alonso-Garcia+ 2018A&A...619A...4A 2018A&A...619A...4A).
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Jul-2021