1. Capabilities and Science Drivers for an X-ray Surveyor Mission
Harvey Tananbaum (SAO)
On behalf of the X-ray Surveyor community
The Universe in High-resolution X-ray Spectra
August 20, 2015

2. X-ray Surveyor Strawman Mission Concept
MSFC ACO Team Led by Randall Hopkins & Andrew Schnell
Strawman definition:
Spacecraft, instruments, optics, orbit, radiation environment, launch vehicle and costing
Performed under the guidance of an informal mission concept team comprised by:
J. A. Gaskin (MSFC), A. Vikhlinin (SAO), M. C. Weisskopf (MSFC), H. Tananbaum (SAO), S. Bandler (GSFC), M. Bautz (MIT), D. Burrows (PSU), A. Falcone (PSU), F. Harrison (Cal Tech), R. Heilmann (MIT), S. Heinz (Wisconsin),
C.A. Kilbourne (GSFC), C. Kouveliotou (GWU), R. Kraft (SAO), A. Kravtsov (Chicago), R. McEntaffer (Iowa),
P. Natarajan (Yale), S.L. O’Dell (MSFC), A. Ptak (GSFC), R. Petre (GSFC), B.D. Ramsey (MSFC), P. Reid (SAO), D. Schwartz (SAO), L. Townsley (PSU)

3. The Strawman X-ray Surveyor Concept is a Successor to Chandra
Angular resolution at least as good as Chandra
Much higher photon throughput than Chandra
Incorporates relevant prior (Con-X, IXO, AXSIO) development and Chandra heritage
Limits most spacecraft requirements to Chandra-like
Achieves Chandra- like cost ($2.95B for Phase B through Launch)

4. Optics & Instruments High-resolution telescope
X-ray Microcalorimeter Imaging Spectrometer
High Definition Imager
Critical Angle Transmission Grating
Chandra
X-Ray Surveyor
Relative effective area (0.5 – 2 keV)
1 (HRMA + ACIS) 50
Angular resolution (50% power diam.)
0.5”
4 Ms point source sensitivity (erg/s/cm2)
5x10-18
3x10-19
Field of View with < 1” HPD (arcmin2) 20
315
Spectral resolving power, R, for point sources
1000 (1 keV)
160 (6 keV)
5000 ( keV)
1200 (6 keV)
Spatial scale for R>1000 of extended sources
N/A 1”
Wide FOV Imaging
16’ x 16’ (ACIS)
30’ x 30’ (HRC)
22’ x 22’
Concept Payload for:
Feasibility
Mass
Power
Mechanical
Costing
NOT THE FINAL
CONFIGURATION

5. Light-Weight, Sub-Arcsecond Optics
Build upon segmented optics approaches for Con-X, IXO, AXSIO
The segmented optics approach for IXO was progressing and a ~10″ angular resolution was demonstrated
Follow multiple technology developments for the reflecting surfaces
Integration
Fabrication
Alignment & Mounting

6. Optics – Specifications & Performance
Wolter-Schwarzschild optical scheme
292 nested shells, 3m outer diameter, segmented design
50×more effective area than Chandra

7. Angular Resolution Versus Off-axis Angle
E < 2 keV
Chandra
Surveyor
- Flat surface
- Optimum
Short segments and Wolter-Schwarzschild design yields excellent wide-field performance.
16x larger solid angle for sub- arcsecond imaging
800x higher survey speed at the CDFS limit

8. Adjustable Optics – Piezoelectric (SAO/PSU)
X-ray reflecting
coating
Deposited
actuator layer
Outer electrode
segment
Micron-level corrections induced with <10V applied to 5–10 mm cells
No reaction structure needed
High yield — exceeds >90% in a university lab
High uniformity — ~5% on curved segments demonstrated
Uniform stress from deposition can be compensated by coating
Row/column addressing
Implies on-orbit correction feasible
2D response of individual cells is a good match to that expected

9. Differential Deposition (MSFC/RXO)
Angstroms
mm along surface
7.1″ to 2.9″ (HPD – 2 reflections) in two passes
HPD (arcseconds)
3.7
2.9
7.1

10. Black Holes: From Birth to Today’s Monsters
How do they co-evolve with galaxies and affect environment?
What is their origin?

11. Black Holes: What is the Nature of Their Seeds?
Light seeds: Pop III star remnants, MBH~102 M☉
Collapse of nuclear star cluster, MBH~103 M☉
Massive seeds: Direct collapse of supermassive star or a quasi-star object, MBH~105 M☉
Sustained super-Eddington growth to MBH~104 M☉
What is their origin?

12. Nature of Black Hole Seeds — First Accretion Light in the Universe
Simulated 2x2 arcmin deep fields with JWST, X-ray Surveyor, and ATHENA
JWST will detect ~2×106 gal/deg2 at its sensitivity limit (Windhorst et al.). This corresponds to 0.03 galaxies per 0.5″ X-ray Surveyor beam (not confused), and 3 galaxies per ATHENA 5″ beam (confused).
Each X-ray Surveyor source will be associated with a unique JWST-detected galaxy. Limiting sensitivity, ~1×10-19 erg/s/cm2, corresponds to LX ~ 1×1041 erg/s or MBH ~ 10,000 M☉ at z=10 —well within the plausible seed mass range.
X-ray confusion limit for ATHENA is 2.5×10-17 erg/s/cm2 (5× worse than current depth of CDFS). Corresponds to MBH ~ 3×106 M☉ at z=10 — above seed mass range. Confusion in O&IR id’s further increases the limit (MBH~107 M☉ at z=8 per ATHENA team).

13. Cycles of Baryons In and Out of Galaxies
Generation of hot ISM in young star-forming regions. How does hot ISM push molecular gas away and quench star formation?
Structure of Cosmic Web through X-ray observations of hot IGM in emission
How did the “universe of galaxies” emerge from initial conditions?

14. Simulated 500 kpc box around a Milky Way type galaxy.
Galaxy Formation: The Nature of Feedback
T~100,000 K
T<10,000 K
T>1,000,000 K
150 kpc
Simulated 500 kpc box around a Milky Way type galaxy.
~ 40% of baryons are converted to stars, ~ 60% ejected outside
~ 30% observable in UV absorption
~ 30% heated to X-ray temperatures — unique feedback signature
Required observations: detect and characterize hot halos around Milky Way-size galaxies to z~1.
Required capability: ~ 100× sensitivity & angular resolution to separate diffuse emission from bright central sources

15. What Physics is Behind the Structure of Astronomical Objects?
Plasma physics, gas dynamics, relativistic flows in astronomical objects:
Plasma flows in Solar system, stellar winds & ISM via charge exchange
Supernova remnants
Neutron star (EOS) and particle acceleration in pulsar wind nebulae
Jet-IGM interactions
Hot-cold gas interfaces in galaxy clusters and Galactic ISM
Off-setting radiative cooling in clusters, groups & galaxies …
Required capability: high-resolution spectra and resolving relevant physical scales

16. Capability Leap: High Throughput X-ray Gratings Spectroscopy
Chandra HETG spectrum of NGC Note the wealth of emission and absorption lines with λ>~10Å (E<~1 keV)
X-ray Surveyor gratings will provide R≈5000 and cm2 effective area: 250× throughput and 5× resolving power compared to Chandra
(50× throughput and 20× resolving power compared to XMM Newton)
Physics of the “New Worlds”, e.g:
Star-planet interactions & atmospheres of “hot Jupiters”
Stellar coronae, winds, & dynamos in sub-stellar regime
Neutron star photospheres
Inner workings of the black hole central engine, e.g:
spectroscopy of outflows
tidal disruption events

17. New Capability: Add 3rd Dimension to the Data
X-ray microcalorimeter will provide high-resolution, high throughput spectroscopy with 1 arcsec pixels — detailed kinematics, chemistry & ionisation state of hot plasmas

18. Plasma Physics with Detailed 3D Tomography
Unsharp mask image
ripples with
thin (< 1″) interfaces
Chandra image of Perseus cluster: energy output from SMBH balances radiative cooling.
Sound waves (in-plane motions) in viscous plasma (Fabian et al 2003)?
Turbulence (line of sight motions) in stratified atmosphere (Zhuravleva et al 2015)?

19. Athena X-ray Surveyor Chandra Key Goals: Key Goals:
Sensitivity (50× better than Chandra)
R≈1000 spectroscopy on 1″ scales, adding 3rd dimension to data
R≈5000 spectroscopy for point sources
Area is built up while preserving Chandra angular resolution (0.5″)
16× field of view with sub-arcsec imaging
Key Goals:
Microcalorimeter spectroscopy (R≈1000)
Wide, medium-sensitivity surveys
Area is built up at the expense of coarser angular resolution (10× worse) & sensitivity (5× worse than Chandra)
Chandra

20. X-Ray Surveyor Science Workshop
Location: National Museum of the American Indian, Washington, D.C.
Date: October 6, 7, 8th
Website: xray_surveyor/
Registration: $100
Format: Invited + Contributed + Posters + Breakout Sessions
Science Organizing Committee
Jessica A. Gaskin (MSFC), Martin C. Weisskopf (MSFC), Harvey Tananbaum (SAO), Alexey Vikhlinin (SAO), Fabbiano Giuseppina (SAO), Christine Jones (SAO), Eric Feigelson (PSU), Neil Brandt (PSU), Leisa Townsley (PSU), Dave Burrows (PSU), Priya Natarajan (Yale), Maxim Markevitch (GSFC), Andrey Kravtsov (Chic.), Steve Allen (Stanford), Sebastian Heinz (Wisc.), Chryssa Kouveliotou (GWU), Roger Romani (Stanford), Feryal Ozel (Ariz.), Richard Mushotzky (UMD), Mike Nowak (MIT), Rachel Osten (STSCI)

21. 2020 Decadal Prioritization
NASA Astrophysics Division white paper: Planning for the 2020 Decadal Survey
Provided an Initial list of missions drawn from 2010 Decadal Survey and 2013 Astrophysics Roadmap that includes the X-ray Surveyor
The three NASA Program Analysis Groups (PAGs) to coordinate community discussion to review and update list of missions
PAG reports will be sent to the Astrophysics Subcommittee and then to the Astrophysics Division for selection of mission concepts to study
Will result in a call for Science and Technology Definition Teams and assignment of lead NASA Center for each study

22. X-ray Surveyor
Scientifically compelling: frontier science from Solar system to first accretion light in Universe; revolution in understanding physics of astronomical systems
Leaps in Capability: large area with high angular resolution for 1-2 orders of magnitude gains in sensitivity, field of view with subarcsec imaging, high resolution spectroscopy for point-like and extended sources
Feasible: Chandra-like mission with regards to cost and complexity with the new technology for optics and instruments already at TRL3 and proceeding to TRL6 before Phase B
Unique opportunity to explore new discovery space and expand understanding of how the Universe works and how it came to look the way we see it