20 th Microlensing Workshop Spitzer Microlens Detection of a Massive Remnant in a Well-separated Binary Yossi Shvartzvald Jet Propulsion Laboratory, California Institute of Technology

20 th Microlensing Workshop Observed Stellar Remnants Single: No single stellar BH detected! A few hundreds NS (pulsars) Binaries: X-ray binaries:  ~75% BH, ~25% NS  22 Galactic BHs (Tetarenko+2015) 5% of NS are in a binary system OB stars – over 70% in binaries (Raghavan+2010)

20 th Microlensing Workshop Observed Stellar Remnants Fryer 2013 Single: No single stellar BH detected! A few hundreds NS (pulsars) Binaries: X-ray binaries:  ~75% BH, ~25% NS  22 Galactic BHs (Tetarenko+2015) 5% of NS are in a binary system OB stars – over 70% in binaries (Raghavan+2010)

20 th Microlensing Workshop All with P a<0.5AU Typical P a<0.1AU BH X-ray binaries – Periods Corral-Santana+2015 ?

20 th Microlensing Workshop BH X-ray binaries – Galactic distribution Corral-Santana+2015

20 th Microlensing Workshop Estimates: ~1% of events are BH and 3% are NS (Gould 2000) Mass measurement: Single lens BHs candidates ( measurement) : MACHO candidates (Poindexter 2005) OGLE - see Wyrzykowski and Rybicki talks on Friday Measure : Finite source size: Astrometric microlensng – see Nucita talk on Friday Interferometric observations – see Ranc talks on Friday Microlensing – single lens detection

20 th Microlensing Workshop Large caustics – measurement => Microlens parallax bias: Microlensing - binary BHs

20 th Microlensing Workshop Large caustics – measurement => Microlens parallax bias: Microlensing planets (orbital parallax): 40% with measurement bias to disk planets Microlensing - binary BHs

20 th Microlensing Workshop Large caustics – measurement => Microlens parallax bias: Microlensing planets (orbital parallax): 40% with measurement bias to disk planets Microlens parallax satellite: Spitzer, Kepler,WFIRST Microlensing - binary BHs

20 th Microlensing Workshop Microlensing - binary BHs Large caustics – measurement => Microlens parallax bias: Microlensing planets (orbital parallax): 40% with measurement bias to disk planets Microlens parallax satellite: Spitzer, Kepler,WFIRST

20 th Microlensing Workshop OGLE-2015-BLG-1285: light curve Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: UKIRT/Wise fields UKIRT/WFCAM microlensing survey: Mauna Kea, 0.2 deg 2 FOV, 0.4’’/pix, H band June 6 – July 15, 5 obs/night, covering 3.4 deg 2 Northern bulge – high extinction 23 OGLE events 12 events observed by Spitzer (pilot) NIR survey: NIR microlensing event rate Source luminosity function 2016 UKIRT support of K2 campaign

20 th Microlensing Workshop OGLE-2015-BLG-1285: UKIRT/Wise fields UKIRT photometry pipeline: PSF photometry (SExtractor +PSFex) >4 million sources ~2% photometric precision

20 th Microlensing Workshop OGLE-2015-BLG-1285: Topologies One symmetric anomaly – limited caustic structures Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: parallax Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: parallax

20 th Microlensing Workshop OGLE-2015-BLG-1285: parallax 1D degeneracy: need for two caustic crossing – implication for future surveys resolvable with future measurement of proper motion direction Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: parallax Compare to previous parallax measurements:

20 th Microlensing Workshop OGLE-2015-BLG-1285: parallax Compare to previous parallax measurements: The smallest microlens parallax measured!

20 th Microlensing Workshop CMD: Highly extincted field OGLE-2015-BLG-1285: Chromatic constraints (V-I) [OGLE]

20 th Microlensing Workshop OGLE-2015-BLG-1285: Chromatic constraints (I-H) [OGLE-UKIRT] CMD: Highly extincted field I [OGLE]- H [UKIRT] Shvartzvald+2015

20 th Microlensing Workshop (I-H) [OGLE-UKIRT] OGLE-2015-BLG-1285: Chromatic constraints CMD: Highly extincted field I [OGLE]- H [UKIRT] Source color same as base: Support - Also from astrometric constraints No blue light!! - rules out early-type main-sequence lenses Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: Physical properties No blue light!! Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: Physical properties Fryer 2013 Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: Physical properties ? Shvartzvald+2015

20 th Microlensing Workshop OGLE-2015-BLG-1285: Physical properties P orb ~ 9 yrs log P orb (h) = 4.9 Shvartzvald+2015

20 th Microlensing Workshop Prospects for future space microlensing Spitzer 2016 (+...): Higher cadence Longer observation Kepler K2C9: Importance for continuous ground-based coverage of the entire K2C9 footprint WFIRST: ~500 BH events and ~1500 NS events Fully explore the stellar remnants mass distribution Including binaries at a few AU

20 th Microlensing Workshop Conclusions  Microlensing can detect stellar remnants in wide binaries  An unexplored field by any other technique currently  Microlens parallax satellite is crucial  High cadence and continuous coverage are essential  OGLE-1285: best microlensing stellar remnant candidate  M>1.35M ʘ (80% probability), no blue light!  Smallest parallax measurement ever  Can be confirmed with future observations  UKIRT : NIR survey - a key preparation program for WFIRST