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wfxt.pha.jhu

The Wide Field X-ray Telescope Andrew Ptak (NASA/GSFC) for the WFXT team. http://wfxt.pha.jhu.edu. Why WFXT?. The only soft X-ray all-sky survey has been the ROSAT All-Sky Survey (RASS) Chandra and XMM-Newton are not survey instruments

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wfxt.pha.jhu

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  1. The Wide Field X-ray Telescope Andrew Ptak (NASA/GSFC) for the WFXT team http://wfxt.pha.jhu.edu

  2. Why WFXT? The only soft X-ray all-sky survey has been the ROSAT All-Sky Survey (RASS) Chandra and XMM-Newton are not survey instruments eRosita is slated to launch in 2017 but has ~ 30” avg. PSF Athena WFI will have 1.4-2 m2 eff. area but will have a 40’ FOV and may only spend ~ 1 year on surveys Brandt & Alexander (2015) We need a dedicated survey mission to cover large areas (> 100 sq. deg.) with flux depths matched to LSST and WFIRST: WFXT would be the X-ray SDSS

  3. WFXT: The SDSS for X-rays XBootes Athena AGN

  4. Typical X-ray Survey Exposure Maps WFXT XMM-COSMOS AEGIS-X XMM-XXL Survey (PI: Pierre) Full XXL area = ~ 50 deg2

  5. eRosita WFXT Will be launched as part of Russian Spektrum Roentgen Gamma (SRG) satellite to L2, planned for Feb 2017 Will detect ~ 105 clusters, 106 AGN 27” HEW FOV-averaged spatial resolution 0.75 deg. FOV effective area ~ 2X XMM-Newton

  6. WFXT Key Features Constant PSF (<= 5” HPD) across 1 degree FOV Effective area ~ 15 X Chandra at 1 keV (goal 10000 cm2) Bandpass: ~ 0.4-7 keV Dedicated survey mission, calibrated data products released with no proprietary period Science goals: discovery and characterization of groups and clusters up z~1-2, evolution of AGN and growth of earliest AGN, star forming galaxies traced up to z>1, halo stars, SNR and compact Galactic objects Will serve as a target finder for future X-ray missions

  7. Grasp Grasp = Aeffx FOV measured at 1.5 keV in cm2 deg2 Grasp measures survey speed Better angular resolution results in better efficiency and source identification.

  8. WFXT Surveys = 1000 X CDFS = 3000 X C-COSMOS

  9. XMM COSMOS survey (2 deg2) (Cappelluti et al. 2009) XMM - 1.5 Msec 1 deg

  10. Chandra COSMOS survey (1 deg2) (Elvis et al. 2009) Chandra - 1.8 Msec Bands (keV)‏ [0.5-2] [2-4.5] [4.5-7]

  11. WFXT simulation (one tile from the medium survey)‏ WFXT - 13 Ksec Bands (keV)‏ [0.5-1] [1.0-2] [2.0-7]

  12. The Bullet cluster (z=0.3, T=14 keV) observed with WFXT Deep survey: 400 ksec z=1.0 z=1.5 z=0.5 10’ Joana Santos (INAF, Osservatorio Astrofisico di Arcetri) and the WFXT Team

  13. Survey Spatial Resolution WFXT • Improve sensitivity for point and extended sources, AGN/cluster/group discernment at any redshift • Minimize source confusion, especially in Deep survey • Efficient identification of optical counterparts, Chandra-like id accuracy (<1” radius error circle, >90% correct IDs), essential for 5x106 AGN and 2×105 clusters • Detect sharp features of the ICM (shocks, cold fronts, cavities) • Resolve cool cores of z>1 clusters (essential for cosmological applications, reliable mass proxy)

  14. Telescope Design WFXT See Pareschi et al. Poster discussing technique to reach WFXT area and FoV requirements with a FOV-averaged HPD < 5” The Wolter New Process design with short segments will enable < few arcsec on-axis performance with < 5” over much of the FoV

  15. Segmented Optics WFXT Courtesy of W. Zhang (GSFC)

  16. WFXT Performance Requirements WFXT

  17. logN-logS WFXT AGN dominate source counts down to ~ 10-17 ergs s-1 cm-2 , ~ 10000 sources deg-2 -> AGN can be selected by finding an X-ray counterpart but must be careful at Chandra Deep Field depths Total Galaxies Lehmer et al. (2012)

  18. Quasar Surveys Courtesy of G. Richards

  19. AGN Z>6 Evolution Very wide range of predictions for z>6 AGN: Observations of significant samples at z>6 would constrain the physics of early BH formation disentangling between several scenarios e.g. providing info on mass of BH seeds, accretion mechanisms

  20. AGN and Galaxies WFXT surveys will detect ~ 107 AGN, 105 galaxies Athena would detect ~ 600,000 AGN in its 1-year notional survey (Aird et al. 2013)

  21. High-Z AGN WFXT • Simulated 400 ksec spectrum of highly obscured, high redshift AGN • NH =1024, Γ=1.82, EWline =1 keV. • 530 counts total • Strong iron line and allows an accurate redshift determination from the X-ray data alone. • Pessimistic case assumes an exponential decline towards high-z in the space density of AGN at all luminosities. • Synergistic: Euclid, LSST and WFIRST identify the WFXT sources, WFXT picks out the AGN (especially high-z, obscured)

  22. Synergy with Wide-Area Surveys WFXT WFXT is the only X-ray mission that will match, in area and sensitivity, the next generation of wide-area O/IR and radio surveys z=6 Medium Survey QSO z=6 Deep Survey QSO

  23. Source Identification (Optical) WFXT SDSS (gvriz) LSST ~1 wk Pan STARRS (gvrizy) LSST 10 yr (ugrizy) Deep100 Medium3000 Wide20,000 CDFS 2 Msec IDs (Luo et al. 2008)

  24. Source Identification (NIR) WFXT VISTA/Viking, 20000 deg2 Euclid, 15000 deg2 Euclid DS 40 deg2 VISTA/VHS, 20000 deg2 WFIRST HLS 2400 deg2 Wide20,000 Deep100 Medium3000

  25. The potential of a WFXT survey With 13 ks: ~L* clusters at z=1.6 detected with ~ 500 counts. 13 ksec exposure With 400 ks: the simulated Spiderweb cluster detected with > 104 counts. Redshifts measured with ~600 counts for the 17 brightest clusters in this field Completely X-ray based cluster redshift survey! Proto-cluster at z=2.1 (400 ksec)‏ z=1.6

  26. The potential of a WFXT survey With 13 ks: ~L* clusters at z=1.6 detected with ~ 500 counts. 13 ksec exposure With 400 ks: the simulated Spiderweb cluster detected with > 104 counts. Redshifts measured with ~600 counts for the 17 brightest clusters in this field Completely X-ray based cluster redshift survey! Proto-cluster at z=2.1 (400 ksec)‏ z=1.6

  27. Science with WFXT: Clusters of galaxies • Not just a cluster counting machine: • • Characterize ICM properties and measure mass proxies for thousands of clusters at z>1. • • Trace the epoch of entropy injection and metal enrichment of the ICM. • • Study the intense dynamics of proto-cluster assembly at z~2. • • Multi-λ synergies: a vast scientific legacy for decades to come • • Path finder for follow-up studies with ELTs, Athena X-IFU, ALMA,...

  28. Science with WFXT: Clusters of galaxies • Not just a cluster counting machine: • • Characterize ICM properties and measure mass proxies for thousands of clusters at z>1. • • Trace the epoch of entropy injection and metal enrichment of the ICM. • • Study the intense dynamics of proto-cluster assembly at z~2. • • Multi-λ synergies: a vast scientific legacy for decades to come • • Path finder for follow-up studies with ELTs, Athena X-IFU, ALMA,... ROSAT WFXT z>1 XMM, Chandra z>1

  29. WFXT Cluster sample Cluster counts (Medium + Deep Surveys) >3,000 clusters at z>0.5, from which z can be measured from Fe line Detection: 50-100 counts T measurements: 1500 counts T profiles: 15,000 counts Temperatures critical to cluster cosmology Profiles, cluster physics, exclude central region Large samples allow study of systematics WFXT can reach into early groups

  30. AGN X-ray variability with WFXT WFXT Deep survey: 400 ks per field, 100 sq.deg - will allow to sample homogeneously broad range of masses and timescales. 30% fluctuations typical in CDFS. The 4 Ms CDFS dataset (courtesy of M. Paolilo)

  31. Wide range of science X-ray counterparts to aLIGO detections GRB afterglows (including orphan / off-axis) Halo stars LMXB and HMXB populations SNR remnants Obscured accretion at high-z Cluster physics: Fe abundance in the ICM, evolution of cool cores in clusters and feedback, low SB regions in the outskirts of clusters Solar System Science Dark Matter search (e.g., Zandanel et al. 2015) …

  32. WFXT Telescope Layout 3 Telescope Design WFXT was studied by the MSFC Advanced Concepts Office (ACO) in 2012 Optics design optimized for wide-field (e.g., Burrows, Burg & Giacconi1992 polynomial perturbation optics design) Mirror: current state-of-the-art technologies are full-shell optics from MSFC and/or Brera (see Pareschi et al. poster) or segmented optics from GSFC Detectors: CCDs baselined in ACO study but more likely would use APS

  33. WFXT Mission Requirements WFXT

  34. Mass and Power WFXT

  35. Mission Parameters WFXT • Chandra-like orbit: 16,000 x 130,000 km • LEO also would be a consideration for lower background, faster ToO response, impact of LEO orbit assessed in ACO study • Total mass 2200 kg (including propellant and launch vehicle adapter) • Structures sized based on FEM analysis • Reaction wheels sized for 12 deg. / min slew rate • Star trackers + ultra-fine sun sensor give 1” pointing knowledge

  36. ACO Cost Estimate WFXT Not including launch vehicle, optics assumed to be at TRL 3-4

  37. Design Trades WFXT • Including a retractable grating • Cost ~ $100-200M • Would recover highly-rated Astro2010 high-resolution spectroscopy science below 2 keV not feasible with Athena • Discussed in NASA PCOS 2011 X-ray Mission Concept Study report • Orbit: LEO vs Chandra-like • Optics Technology: segmented vs full-shell optics

  38. Conclusions WFXT • Current soft X-ray surveys consist of the RASS, shallow serendipitous source / slew surveys (~ hundreds of sq. deg.), medium-deep surveys (several sq. deg.), Chandra deep fields (< 1 sq. deg) that probe cluster, AGN and galaxy evolution, AGN absorption, black hole growth, etc. • Current X-ray satellites limited by FOV and/or background, primary pointed missions • eRosita will survey soft X-ray sky at ~ 10X RASS sensitivity, will detect ~ 105 clusters, ~ 106 AGN, 103-4 galaxies • Athena WFI baseline is to spend ~ 1 year surveying <~ 100 deg2 • WFXT will survey soft X-ray size at ~ 10-100X eRosita sensitivity (due to higher grasp, sharper and constant PSF, longer exposures) truly matching deep survey sensitivities for LSST, Euclid and WFIRST • will detect ~ 106 clusters, ~ 107 AGN, 104-5 galaxies

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