J/ApJS/280/49ivo://CDS.VizieR/J/ApJS/280/49CDSMroz P.Udalski A.Szymanski M.K.Soszynski I.Pietrukowicz P.,Kozlowski S.Poleski R.Skowron J.Skowron D.Ulaczyk K.,Gromadzki M.Rybicki K.Iwanek P.Wrona M.Ratajczak M.2026-07-22T09:43:29Z2026-07-22T10:28:34ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgravitational-lensinginfrared-photometryvisible-astronomyphotometrySome previous studies have suggested that massive and intermediate-mass primordial black holes (PBHs) could comprise a substantial fraction of dark matter in the Universe. Such black holes, if they existed in the Milky Way halo, would give rise to long-duration microlensing events that may potentially last for years. However, earlier searches were not sufficiently sensitive to detect such events. Here, we present the results of searches for long-timescale gravitational microlensing events toward the Small Magellanic Cloud (SMC) using nearly 20yr of photometric observations collected by the Optical Gravitational Lensing Experiment (OGLE) from 2001-2020. We found six events, three of which are new discoveries. We use a sample of five events to measure the microlensing optical depth toward the SMC {tau}=(0.32{\pm}0.18)x10^-7^ and the event rate {Gamma}=(1.18{\pm}0.57)x10^-7^/yr/star. The properties of the detected events are consistent with lenses originating from known stellar populations within the SMC or in the Milky Way disk. No events with timescales longer than 1yr were detected, which provides competitive limits on the fraction of massive compact objects, including PBHs, in the Milky Way dark matter halo. Together with the earlier OGLE studies of microlensing events in the direction of the Large Magellanic Cloud, these observations rule out PBHs and other compact objects with masses ranging from 10^-8^-10^3^M_{sun}_ as dominant components of dark matter.2025ApJS..280...49Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/280/49CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/AcA/50/421 : OGLE-II DIA BUL_SC1 field (Wozniak, 2000)J/A+A/529/A102 : MOA-2007-BLG-387Lb light curve I band (Batista+, 2011)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/ApJS/244/29 : Microlensing events toward the Galactic bulge (Mroz+, 2019)J/ApJ/904/13 : Radial velocity for 10 giant EBs (Graczyk+, 2020)J/A+A/649/A7 : MC structure and properties (Gaia Collaboration+, 2021)J/ApJS/252/23 : Reddening map of MCs from OGLE-IV RC stars (Skowron+, 2021)https://www.astrouw.edu.pl/ogle/ogle4/SMC_OPTICAL_DEPTH/ : associated data ofthis paper (also doi:10.5281/zenodo.16735482)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/280/49https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/280/49http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/280/49https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/280/49https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/280/49http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/280/49GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/280/49/table1 (OGLE-IV fields toward the Small Magellanic Cloud)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/280/49/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/280/49/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/280/49/table1?GETtext/xml+votable180.050000true3.8375-69.443610.005555555555555556Cone search capability for table J/ApJS/280/49/subfields (Number of microlensing source stars observed in OGLE-IV fields (Table 6) and Error bar correction coefficients for the I-band data (Table 2))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/280/49/subfields?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/280/49/subfields?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/280/49/subfields?GETtext/xml+votable180.050000true5.1554-69.91440.005555555555555556Cone search capability for table J/ApJS/280/49/table4 (Detected microlensing events)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/280/49/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/280/49/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/280/49/table4?GETtext/xml+votable180.050000true10.1171667-73.746250.0055555555555555564/2058 2080 2082-2083 2088-2090 5/8225 8227 8238 8324 8326-8327 8364-8366 8368 8370 8704 11284-11285 11328-11329 11332-11333 11344-11345 11348-11349 11520-11521 6/32811 32814-32815 32897 32899 32905-32907 32914 32920 32922 32944 32946-32947 32958 33300 33302-33303 33354 33376 33378 33384 33386 33468 33504 34820-34822 34824-34826 34828 34832 34848 45127 45133 45144-45145 45148-45149 45320-45321 45324-45325 45336-45337 45340-45341 45384-45385 45388-45389 45400-45401 45404-45405 46088-46089 46092 46096https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/280/49?format=asciiOpticalInfrareddefaultJ/ApJS/280/49/table1OGLE-IV fields toward the Small Magellanic CloudrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldOGLE-IV field name (SMCNNN)meta.id;meta.maincharprimaryRAJ2000Hour of Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainNepoch1[0/702] Minimal number of OGLE-III epochs in I band; 2001-2009meta.numberintNepoch2[0/3318] Maximal number of OGLE-III epochs in V band; 2001-2009meta.numberintNepoch3[151/1090] Number of OGLE-IV epochs in I band; 2010-2020meta.numberintNepoch4[7/321] Number of OGLE-IV epochs in V band; 2010-2020meta.numberintNstars1[0/1463.1] Number of stars observed during both OGLE-III and OGLE-IV; in thousandsmeta.numberfloatNstars2[0/137.9] Number of stars observed during OGLE-IV only; in thousandsmeta.numberfloatNstars3[21.3/1473] Total number of stars; in thousandsmeta.numberfloatNsfNumber of subfields for this field (link to Tables 2+6)meta.numberintnullableJ/ApJS/280/49/subfieldsNumber of microlensing source stars observed in OGLE-IV fields (Table 6) and Error bar correction coefficients for the I-band data (Table 2)FieldOGLE-IV field name (SMCNNN)obs.fieldcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintsFieldOGLE-IV subfield name (NN; SMCNNN.NN for a complete designation)meta.id;meta.mainintRAJ2000Right ascention (J2000)degpos.eq.ra;meta.mainDEJ2000[-83/-62.7] Declination (J2000)degpos.eq.dec;meta.mainN21Tot[398/174447] Total number of sources brighter than I=21 magmeta.numberintN21Corr[0/173678] Corrected number of sources brighter than I=21 magmeta.numberintN21.5Tot[434/244105] Number of sources brighter than I=21.5 magmeta.numberintN21.5Corr[0/243240] Corrected number of sources brighter than I=21.5 magmeta.numberintN22Tot[481/338613] Total number of sources brighter than I=22 magmeta.numberintN22Corr[0/337698] Corrected number of sources brighter than I=22 magmeta.numberintgam3[0.9/1.96]? Gamma coefficient for OGLE-III datastat.fit.paramfloatnullableeps3[0.005/0.021]? Epsilon coefficient for OGLE-III datastat.fit.paramfloatnullablegam4[0.8/2.21] Gamma coefficient for OGLE-IV datastat.fit.paramfloateps4[0.002/0.15] Epsilon coefficient for OGLE-IV datastat.fit.paramfloatJ/ApJS/280/49/table4Detected microlensing eventsSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEventMicrolensing event namemeta.id;meta.maincharRAJ2000[0/1] Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[72/73] Degree of declination (J2000)pos.eq.dec;meta.mainOGLEIVOGLE-IV identifier(s)meta.idcharImag[18.2/20.65] I band magnitudemagphot.mag;em.opt.Ifloate_Imag[0.01/0.012] Uncertainty on the Imagmagstat.error;phot.mag;em.opt.IfloatV-I[0.001/1.16] V-I color indexmagphot.color;em.opt.V;em.opt.Ifloate_V-I[0.014/0.017] V-I uncertaintymagstat.error;phot.color;em.optfloatE(V-I)[0.03/0.12] V-I color excessphot.color.excess;em.opt.V;em.opt.Ifloate_E(V-I)[0.029/0.071] Lower uncertainty on E(V-I)stat.error;stat.min;phot.color.excessfloatE_E(V-I)[0.026/0.065] Upper uncertainty on E(V-I)stat.error;stat.max;phot.color.excessfloatLCInteractive LC plotmeta.ref.urlchar