# Presentation: 710675

## Light-weight X-ray Optics for Surveys

* **developments at ESA & Lessons from XMM **Ω **Project*
**David Lumb, **
** ****Science Payloads Office**

## Scope of the talk

**Review the analysis of clusters for the ****XMM-Newton ****Ω Project**** – ***what lessons for designing X-ray Survey Missions*
**ESA developments for light-weight  X-ray optics that might be used for future survey missions**
**Microchannel plate optics**
** ****XEUS**** high performance optics**

## XMM-Newton Ω Project

**Cluster abundance probe of cosmology via. temperature function**
**Obtain by applying L-T relation of flux-limited sample**
**XMM-Newton used to obtain temperature data on clusters for ****z>0.3****, obtained from ****SHARC**** catalogues**
**The Guaranteed Time phase of this project comprised ****8 clusters to z=0.62**
**L-T data reported in ***astro-ph / 0311344***    (accepted for A&A)**
**Matches the L-T evolution reported for CHANDRA data set (Vikhlinin et al)**

## Selected Cluster Images

## XMM Data – Notes re. PSF

**Clusters are resolved at all redshifts, PSF core FWHM ~ 6 arcsec**
**PSF varies little with energy and off-axis angle**
**Systematic effects arising from PSF mis-calibration are then minimal**
**Anomalous r****c**** in ****β – model ****fits provide evidence for CF clusters (excise for L-T data)**

## XMM Data – Notes re. PSF

**Clusters are resolved at all redshifts, PSF core ****FWHM ~ 6 arcsec**
**PSF varies little with energy and off-axis angle**
**Systematic effects arising from PSF mis-calibration are then minimal**
**Anomalous r****c**** in ****β – model ****fits provide evidence for CF clusters (excise for L-T data)**
**β – model ****fits provide robust measure to correct luminosity to ****r****vir****, for example**
*Caution r**c **&** **β can be correlated in the fitting*

## Background Issues

**XMM-Newton orbit ****~30%**** observation time affected by magnetospheric proton reconnection flares (seasonal and positional) and cosmic ray flux influenced by solar max conditions**
**Filter flares, take in-field backgrounds, model proton vignetting (***otherwise some clusters ~80keV temperature!***)**
**Note that even low earth equatorial orbit will see changes from heliospheric X-ray emisison so may need proxy solar wind monitor (***latest work on XMM HDF fields by Snowden & Kuntz***) **

## Some General Issues

**For XMM the in-orbit calibration of vignetting and X-ray stray-light rejection are solved but has been long & tedious ***– consider carefully in calibration plans*
**Redshift always matches optical (~****0.05**** in our data) – ***useful to have sufficient area for iron line centroiding*
**Pay attention to instrumental background issues (EPIC PN spatially variable, Low energy emission lines)**
**Considering detection alone, a 6keV temperature cluster at ****z=0.5**** has ****90%**** of flux at energies ****<3.8keV****, & for gold critical angle implies focal length ****>2.5 m**

## Microchannel Plate Optics

**Square pore MCP**** glass technology – core glass is stiffer than cladding & defines interface shape during drawing**
**The surface roughness is improved by the ****~100****2**** drawing factor that modifies surface structure**
**Multi-fibre bundles fused and drawn again**
**Assembled into the required radial geometry, then fused sliced and slumped to required shape, & etched**

## Microchannel Plate Optics

**Effective area maximised with large number concentric reflectors.**
**Two MCPs needed for double reflection**
**Mirror thickness is substantially reduced**

** ****Conical approximation to Wolter-I**

## Prototype

**Prototype 60mm MCP optics   - 29g only **

## Prototype Performance

- Radially packed
- MCP X-ray Optics
- E=10keV
- ØMCP= 40mm
- Scale: 0.8”/pxl
- FWHM=20”

## Recent ESA developments

**Needed to improve metrology in drawing process, quality of glass, fibre stacking and slumping**

## Metrology Now Implemented

**On-line continuous metrology in feedback loop during the draw process**

## Improvements in fabrication

- Cladding glass geometry after 1st draw

- Old

- New

## Improvements in fabrication

- Old system

- New system

- Angles vary in range of 2.5 degrees

- Angles vary in range of 0.5 degrees

- Angles vary in range of 2.5 degrees

- Angles vary in range of 0.5 degrees

## X-ray optics Mass

**MCP optics: **
**~ 29g for 60mm diameter, **
**~10kg/m****2**
**XMM-size: 4 kg**

**XMM optics: **
**~ 350 kg for 700mm diameter, **
**~910kg/m****2**

## Simulation of MCP Optics

**Simulated a ****5 10****43**** erg/s**** cluster at ****z=0.5****, for a range of MCP optics focal length and radii**

** ****A ****5****σ**** detection in ****1 ksec**** is possible with a ****0.2m**** radius optic at focal length ****5m**

## MCP Optics Simulation

**Field simulated with ****15 arcsec**** FWHM, ****3 ksecs, 0.7****°**** square. ****L****6**** clusters at ****z=0.7**
**Mass of focussing optics  < 10kg !!**

## XEUS Optics

***X-ray Early Universe Explorer***** – ESA’s follow on from XMM-Newton**
**Baseline concept for a 8m****2**** area telescope to be expanded at ISS to >30m****2 ****  **
**Angular resolution requirement 2 – 5 arcsec with 1 arcsec goal**
**50m focal length with separate formation-flying detector and mirror spacecraft**

## XEUS Optics

***X-ray Early Universe Explorer***** – ESA’s follow on from XMM-Newton**
**Baseline concept for a ****6m****2**** area telescope to be expanded at ISS to ****>30m****2**** ****  **
**Angular resolution requirement ****5**** arcsec with a goal ****1 - 2 arcsec **
**50m**** focal length with separate formation-flying detector and mirror spacecraft**
**Developing very light weight optic solution to avoid multiple launches and ISS deployment**

## XEUS Science Goals

**Early Universe BH formation and structures, e.g. ****X-ray spectral features of 0.3 solar enriched small cluster at z=2**

## Conclusions

**X-ray wide angle surveys need angular resolution ****15**** arcsec (detection), ~****5 ****arcsec for detailed analysis**
**Large fraction of sky in 1 year => few ksec, square degree field and 10****3**** cm****2**
**MCP optics already offers ****25**** arcsec FWHM with developments under way for improved resolution –telescope mass ****< 10kg**
**First generation XEUS optics are under development with rapid progress towards ****5 arcsec**** resolution**
**This technology could be used for X-ray astronomy payloads enabling telescopes of several square metres in one launch to L2**