HST Treasury Program HST Treasury Program GO13826 (PI M.Robberto) - - PowerPoint PPT Presentation

HST Treasury Program

HST Treasury Program GO13826 (PI M.Robberto) WFC3 IR Data:

• Target: Orion Nebula
• 52 Visit
• Area: ~ 1/6th of square

degree

• Filters: F130N, F139M

Robberto et al. 2019, submitted

The problem: galactic confusion at substellar masses

Robberto et al. 2010, AJ 139, 950

Orion Nebula Cluster Orion Nebula Cluster Milky Way Milky Way

Kirkpatrick, J. Davy 2005

Solution: Water in absorption feature

WFC3 IR Channel:

• F130N (red line)
• F139M (blue line)

CMD and cluster/background selection

The chosen color index splits the low mass and substellar members

• f the Orion Nebula Cluster from

the Galactic background Robberto et al 2019

CMD and cluster/background selection

Cluster sources:

• 10.9 ≤ mag130 ≤ 22
• 3104 MULTIPLE VISITS targets
• 2816 isolated targets (no stars ≤ 1.5'')

Robberto et al 2019

Building the Local PSF

• Each dot indicates the position
• f a point source on the detector

(2816 isolated sources in our survey)

• Detector area is divided in 10x10

quadrants of 102x102 pixels

• Stars

within a quadrant are grouped together for analysis

Building the Data Frame

• WFC3 pixel scale = 0.13''
• 11x11 pixel postage stamp (~1.5''x1.5'')

Building the Data Frame

• For each star, we use all other

stars in the same quadrant to create a model PSF

• Subtract the model PSF from the

star using KLIP algorithm (Pueyo 2016)

Preliminary Catalog: Selection Criteria

• residual distributon as like a Normal distribution;
• ‘Minimum’ threshold selection to detect outliers

defined by the sigma of the post- subtraction pixel histogram;

Outlier

Preliminary Catalog: Selection Criteria

• 1. Presence of the detection in

both filters

• 2. Persistance of the detection

through different KLIP modes

• 3. Same position within 1 pixel

(taking into account telescope rotation)

more aggressive PSF subtraction

Photometry and mass estimate

D + + e esky emag 2 2

Photometric calibration:

• primaries PSF photometry
• 4 pixel aperture photometry for all

primaries

• conversion

factor (Δ) between 4- pixel/PSF photometry to the photometry

• f the companions

Companions magnitude errors sources: Mass estimate:,

• Comparison

between de-reddend photometry and isochrone

• AV from DaRio et al. 2016 and Robberto

et al 2019

𝑓𝑛𝑏𝑕2 + 𝑓𝑡𝑙𝑧2 + 𝑓∆2

Candidate companions: Final Selections

Control Sample:

• MULTIPLE

visit sources WHITOUT any candidate detection in it, considered as SINGLE visit

Candidate companions: Final Selections

Moving threshold Control Sample:

• MULTIPLE

visit sources WHITOUT any candidate detection in it, considered as SINGLE visit False Positive analysis:

• any detection is a FP
• FP

ratio ≤ 1/10th

• f

expected signal

Candidate companions: Final Selections

Moving threshold Control Sample:

• MULTIPLE

visit sources WHITOUT any candidate detection in it, considered as SINGLE visit False Positive analysis:

• any detection is a FP
• FP

ratio ≤ 1/10th

• f

expected signal New Catalog:

• new

thresholds aplied to the preliminary catalog

Candidate Companions: Contrast Curves

Contrast curves for 50% completeness

Candidate Companions: Examples

Candidate Companions: Examples

ACS (Robberto et al 2013): WFC3:

KLIP canididate detections

KLIP + Robberto et al 2019 WIDE binaries

Blue: Robberto et al. 2019 binaries with separation ≤ 1.5'' Green: KLIP binaries with sepataion ≤ 1.5'' Binary fraction: 11.9% ± 0.8%

Completeness Curves

Completeness (c) curves from fake-injection analysis. c ≥ 80 at projected sami major axis (SMA) ≥ 0.4 and masses:

• MC ≥ 100 MJ for primary masses MP ≥ 75 MJ
• MC ≥ 10 MJ for primary masses 13 MJ ≤ MP ≤ 75 MJ

Spatial properties

Kolmogorov Smirnov test p-value > 0.1

Close binaries: separation ≤ 0.6'' Wide binaries: separation > 0.6''

Close binaries Wide binaries

Mass distribution

Both distributions are compadible within the errors

Mass ratio

Mass Ratio

Symbol Primary Mass circle Mp ≥ 75 MJ diamond 13 MJ ≤ Mp < 75 MJ triangle Mp < 13 MJ

Summary

• We have applied the KLIP PSF subtraction algorithm to a large dataset of wide-

field HST images to uncover faint companions with separations between 0.17"- 0.78'' (70-314 AU)

• We detect 67 companions with H2O in absorption
• Mostly complete (c ≥ 80%) at projected sami major axis ≥ 0.4 and masses:
• MC ≥ 100 MJ for primary masses MP ≥ 75 MJ
• MC ≥ 10 MJ for primary masses 13 MJ ≤ MP ≤ 75 MJ
• ONC binary fraction = 11.9% ± 0.8%;
• Mass ratio heavy tale with a median value of ~ 0.35 [Mprimary/Mcompanion];

Chance alignment