RAS E-ELT meeting9th May 08

Fraser Clarke

Towards EPICS; high contrast spectroscopy

Fraser ClarkeN Thatte, G Salter, M Tecza

C Verinaud, M Kasper (EPICS co-PIs)R Gratton (EPICS science team)

RAS E-ELT meeting9th May 08

Fraser Clarke

EPICS top level requirements

• EPICS is the proposed planet finding instrument for the E-ELT• Two modes of operation

– Imaging spectroscopy– Polarimetric imaging

• Top Level Requirements– 600-1700nm (goal 350-2500nm) [600-900 for Polarimetry]– R>50 for discovery; R>>50 for characterisation [Spectroscopy]– Nyquist sampled imaging (2mas/pixel)– 2” FoV (goal 4”)– Inner Working Angle < 30mas (goal 15mas)– Strehl at H~90% (I=9) [>50% at 600nm for Polarimetry]– Coronagraphic rejection better than 104 (tbc)– Polarimetric sensitivity 10-5

• Phase A study underway now. Due to be completed by Oct 2009.

RAS E-ELT meeting9th May 08

Fraser Clarke

EPICS key science

1. Young self-luminous gas giants in star forming regions or young associations

– Determine frequency and mass distribution of giant planets

2. Detection and characterisation of mature gas giants at orbital distances between ~5 and 15AU in the solar neighbourhood (15pc)

3. Imaging and characterisation of warm or young Jupiters previously found by R.V. or imaging searches with smaller telescopes

– Understand giant planets’ atmospheric composition and structure

4. Detection and 1st order characterisation of warm Neptunes, massive rocky planets and super-Earths around very nearby stars (<10pc); with ultimate goal of detecting such planets

located in the HZ (M-dwarfs and systems <4pc)

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RAS E-ELT meeting9th May 08

Fraser Clarke

EPICS consortium

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G Tinetti (UCL)

RAS E-ELT meeting9th May 08

Fraser Clarke

Oxford involvement in EPICS

• Niranjan Thatte leads IFS workpackage– Oxford concentrates on Image Slicers– INAF/Padova (R Gratton) developing “BIGRE” lenslet

approach

• Oxford deliverables; – IFS optical design analysis– Slicer prototype– SINFONI coronagraph (not funded in EPICS Phase A,

but present in list of deliverables!)– Data reduction algorithms

RAS E-ELT meeting9th May 08

Fraser Clarke

Speckles; limits on high contrast

• Light not put into diffraction limited core of PSF interferes coherently to produce speckles

• Some speckles, caused by imperfections in optical train, are long lasting (many minutes, or more), and cannot be integrated out– Super-speckles

• Super-speckles are diffraction limited, and look like real objects at a given wavelength

• => Major limit to contrast in current systems

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RAS E-ELT meeting9th May 08

Fraser Clarke

A third way… (wavelength)

Speckles scale with wavelength (/D), so they move out from central star as one goes to longer wavelengths

Planets are at a fixed position on the sky which doesn’t change with wavelength

Use wavelength scaling of Airy pattern and speckles to remove starlight and isolate planet’s signature.

(Sparks & Ford 2002)

RAS E-ELT meeting9th May 08

Fraser Clarke

Concept demonstrator

• AB Dor C as target• 5 mag fainter companion 200 mas away• VLT + SINFONI data• DDT P76 (end of January 2006)• 2 x 20 min on-source in two rotator settings• First Airy Null at 60 mas in K band.• Results published in;

– Thatte et al 2007, MNRAS, 378, 1229– Close et al 2007, ApJ, 665, 736

RAS E-ELT meeting9th May 08

Fraser Clarke

Spectroscopy at the diffraction limit

Input data cube

(normalised)

RAS E-ELT meeting9th May 08

Fraser Clarke

Spectroscopy at the diffraction limit

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• Subtracted azimuthally averaged PSF

• Stepping through in wavelength from 1.45-2.4um

RAS E-ELT meeting9th May 08

Fraser Clarke

Super speckles in the raw data

• Subtract azimuthally averaged PSF

• Monochromatic image

• Super-speckles clearly visible

RAS E-ELT meeting9th May 08

Fraser Clarke

Super speckles after processing

• Same wavelength slice after SD technique

• Speckles well removed

RAS E-ELT meeting9th May 08

Fraser Clarke

9 mag at 0.2” w/o coronagraph!!

Thatte et al, 2007, MNRAS, 378, 1229

RAS E-ELT meeting9th May 08

Fraser Clarke

Spectra of AB Dor C

RAS E-ELT meeting9th May 08

Fraser Clarke

Spectral type of AB Dor C

Close et al., 2007,ApJ, 665, 736

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RAS E-ELT meeting9th May 08

Fraser Clarke

Steps towards EPICS

• Continuing to improve SD technique for EPICS data (Graeme Salter)

• Simulated data cube provided by C Verinaud for EPICS– 1024x1024 with 444 wavelengths– Many speckles and “N” planets…

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RAS E-ELT meeting9th May 08

Fraser Clarke

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Found 6 of 7 planets!• SD technique found 6 of 7 planets in the datacube (Differential imaging

only found 2)• Particularly good further from star, where speckles move more. • Tiger-stripe issue understood (fitting error), and should be fixed now

RAS E-ELT meeting9th May 08

Fraser Clarke

Summary

• EPICS phase A study progressing, and due for submission to ESO by Oct 2009

• Oxford leading IFS work package• Many pronged approach to investigating

high contrast capabilities of image slicers1. Slicer bench test in the lab2. SINFONI coronagraph test on sky3. Optical design analysis4. Development of new data reduction techniques

RAS E-ELT meeting9th May 08

Fraser Clarke

Progress - slicer prototype

• Price quote for slicer prototype• 1 arm spectrograph optics available• Need lab test up with phase screen,

and simple coronagraph (or should we move our setup somewhere else)

• Procurement for detector and readout system launched.

RAS E-ELT meeting9th May 08

Fraser Clarke

Progress - SINFONI coronagraph

• Proposal to ESO for instrument upgrade in preparation

• MPE would not like to be formally involved, but offers to help.

• Request for manpower funding to go in to STFC soon (already?)

• Hardware funding? (ESO)