TY - JOUR

T1 - The abundance of Galactic planets from OGLE-III 2002 microlensing data

AU - Snodgrass, Colin

AU - Horne, Keith Douglas

AU - Tsapras, Yiannis

PY - 2004/7/1

Y1 - 2004/7/1

N2 - From the 389 OGLE-III 2002 observations of Galactic bulge microlensing events, we select 321 that are well described by a point-source point-lens light-curve model. From this sample we identify one event, 2002-BLG-055, that we regard as a strong planetary lensing candidate, and another, 2002-BLG-140, that is a possible candidate. If each of the 321 lens stars has one planet with a mass ratio q = m/M = 10(-3) and orbit radius a = R-E, the Einstein ring radius, analysis of detection efficiencies indicates that 14 planets should have been detectable with Deltachi(2) > 25. Assuming our candidate is due to planetary lensing, then the abundance of planets with q = 10(-3) and a = R-E is n(p) approximate to n/14 = 7 per cent. Conversion to physical units (Jupiter masses, M-Jup, and astronomical units, au) gives the abundance of 'cool Jupiters' (m approximate to M-Jup, a approximate to 4 au) per lens star as n(p) approximate to n/5.5 = 18 per cent. The detection probability scales roughly with q and (Deltachi(2))(-1/2), and drops off from a peak at a approximate to 4 au like a Gaussian with a dispersion of 0.4 dex.

AB - From the 389 OGLE-III 2002 observations of Galactic bulge microlensing events, we select 321 that are well described by a point-source point-lens light-curve model. From this sample we identify one event, 2002-BLG-055, that we regard as a strong planetary lensing candidate, and another, 2002-BLG-140, that is a possible candidate. If each of the 321 lens stars has one planet with a mass ratio q = m/M = 10(-3) and orbit radius a = R-E, the Einstein ring radius, analysis of detection efficiencies indicates that 14 planets should have been detectable with Deltachi(2) > 25. Assuming our candidate is due to planetary lensing, then the abundance of planets with q = 10(-3) and a = R-E is n(p) approximate to n/14 = 7 per cent. Conversion to physical units (Jupiter masses, M-Jup, and astronomical units, au) gives the abundance of 'cool Jupiters' (m approximate to M-Jup, a approximate to 4 au) per lens star as n(p) approximate to n/5.5 = 18 per cent. The detection probability scales roughly with q and (Deltachi(2))(-1/2), and drops off from a peak at a approximate to 4 au like a Gaussian with a dispersion of 0.4 dex.

KW - gravitational lensing

KW - techniques : photometric

KW - planetary systems

KW - EVENTS

UR - http://www.scopus.com/inward/record.url?scp=3042853039&partnerID=8YFLogxK

UR - http://www.blackwell-synergy.com/journals/resolver.asp?bibcode=2004MNRAS.351..967S&format=

U2 - 10.1111/j.1365-2966.2004.07839.x

DO - 10.1111/j.1365-2966.2004.07839.x

M3 - Article

SN - 0035-8711

VL - 351

SP - 967

EP - 975

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

IS - 3

ER -