J/MNRAS/457/4089 Frequency of snowline-region planets (Shvartzvald+, 2016)
The frequency of snowline-region planets from four years of
OGLE-MOA-Wise second-generation microlensing.
Shvartzvald Y., Maoz D., Udalski A., Sumi T., Friedmann M., Kaspi S.,
Poleski R., Szymanski M.K., Skowron J., Kozlowski S., Wyrzykowski L.,
Mroz P., Pietrukowicz P., Pietrzynski G., Soszynski I., Ulaczyk K., Abe F.,
Barry R.K., Bennett D.P., Bhattacharya A., Bond I.A., Freeman M.,
Inayama K., Itow Y., Koshimoto N., Ling C.H., Masuda K., Fukui A.,
Matsubara Y., Muraki Y., Ohnishi K., Rattenbury N.J., Saito T.,
Sullivan D.J., Suzuki D., Tristram P.J., Wakiyama Y., Yonehara A.
<Mon. Not. R. Astron. Soc., 457, 4089-4113 (2016)>
=2016MNRAS.457.4089S 2016MNRAS.457.4089S (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Gravitational lensing ; Stars, double and multiple ;
Planets
Keywords: gravitational lensing: micro - surveys - binaries: general -
planetary systems - Galaxy: stellar content
Abstract:
We present a statistical analysis of the first four seasons from a
'second-generation' microlensing survey for extrasolar planets,
consisting of near-continuous time coverage of 8 deg2 of the
Galactic bulge by the Optical Gravitational Lens Experiment (OGLE),
Microlensing Observations in Astrophysics (MOA), and Wise microlensing
surveys. During this period, 224 microlensing events were observed by
all three groups. Over 12 per cent of the events showed a deviation
from single-lens microlensing, and for ∼one-third of those the
anomaly is likely caused by a planetary companion. For each of the 224
events, we have performed numerical ray-tracing simulations to
calculate the detection efficiency of possible companions as a
function of companion-to-host mass ratio and separation. Accounting
for the detection efficiency, we find that 55+34-22 per cent of
microlensed stars host a snowline planet. Moreover, we find that
Neptune-mass planets are ∼10 times more common than Jupiter-mass
planets. The companion-to-host mass-ratio distribution shows a deficit
at q∼10-2, separating the distribution into two companion
populations, analogous to the stellar-companion and planet
populations, seen in radial-velocity surveys around solar-like stars.
Our survey, however, which probes mainly lower mass stars, suggests a
minimum in the distribution in the super-Jupiter mass range, and a
relatively high occurrence of brown-dwarf companions.
Description:
Our genII survey network is a collaboration between three groups:
OGLE, MOA, and Wise. The OGLE and MOA groups regularly monitor a large
region of the Galactic bulge, and routinely identify and monitor
microlensing events. The Wise group monitors a field of 8 deg2, within
the observational footprints of both OGLE and MOA, having the highest
event rates based on previous years' observations (see Shvartzvald &
Maoz, 2012MNRAS.419.3631S 2012MNRAS.419.3631S).
The sample of microlensing events analysed here consists of 224 events
from the 2011-2014 bulge seasons, observed by all three groups, and
with each group having data near the peak of the event.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 133 230 Event summary
--------------------------------------------------------------------------------
See also:
J/AcA/50/1 : OGLE microlensing events in Galactic Bulge (Udalski+, 2000)
J/AcA/51/175 : OGLE-II DIA microlensing events (Wozniak+, 2001)
J/ApJ/636/240 : OGLE II microlensing parameters (Sumi+, 2006)
J/ApJ/711/L48 : 2008 OGLE Bulge microlensing alerts (Cohen+, 2010)
J/ApJS/216/12 : OGLE-III Galactic bulge microlensing events (Wyrzykowski+ 2015)
J/ApJ/778/150 : MOA-II microlensing events toward the Bulge (Sumi+, 2013)
J/ApJ/827/139 : MOA-II microlensing optical depth + event rates (Sumi+, 2016)
Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- Seq Sequential number (1-224) +
6 (X1-X6) anomalous events
5- 11 A7 --- OGLE OGLE number (NN-NNNN, EWS 20NN-BLG-NNNN)
13- 18 A6 --- MOA MOA number (NN-NNN, MOA 20NN-BLG-NNN)
20- 25 F6.3 --- mu0 Minimum impact parameter
27- 34 F8.3 d t0 Time of the closest lens-source approach
(HJD-2450000)
36- 42 F7.3 d tE Einstein radius crossing time
(the events time-scale)
44- 51 F8.3 10-3 rho ?=0 Angular Einstein radius (rho=theta*/thetaE)
52 A1 --- n_rho [*] Note on rho (1)
53- 58 F6.3 --- piEE East component of the orbital microlens
parallax vector piE
59 A1 --- n_piEE [*] Note on piEE (1)
60- 65 F6.3 --- piEN North component of the orbital microlens
parallax vector piE
66 A1 --- n_piEN [*] Note on piEN (1)
67- 72 F6.3 mag Ibl Baseline magnitude
74- 78 F5.3 --- fbl Baseline flux
80- 85 F6.3 --- e_mu0 rms uncertainty on mu0
86- 91 F6.3 d e_t0 rms uncertainty on t0
93- 99 F7.3 d e_tE rms uncertainty on tE
101-109 F9.3 10-3 e_rho rms uncertainty on rho
111-115 F5.3 --- e_piEE rms uncertainty on piEE
117-121 F5.3 --- e_piEN rms uncertainty on piEN
123-127 F5.3 mag e_Ibl rms uncertainty on fbl
129-133 F5.3 --- e_fbl rms uncertainty on fbl
--------------------------------------------------------------------------------
Note (1): * indicates significant detections of finite source effects and
parallax.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 01-Jun-2017