Wide Field X-ray Telescope
The Ultimate X-ray Survey Mission
European WFXT site

The Wide Field X-Ray Telescope (WFXT) is a medium-class mission designed to be 2-orders-of-magnitude more sensitive than any previous or planned X-ray mission for large area surveys and to match in sensitivity the next generation of wide-area optical, IR, and radio surveys. Using an innovative wide-field X-ray optics design, WFXT provides a field of view of 1 square degree (10x Chandra) with an angular resolution of 5" (Half Energy Width, HEW) nearly constant over the entire field, and a large collecting area (1 m2, >10x Chandra) over the 0.1-7 keV band. WFXT's low-Earth orbit also minimizes the particle background. In five years of operation, WFXT will generate a legacy astrophysical data set of more than 5×105 clusters of galaxies to z∼2, 107 AGN to z > 6, and ∼105 normal and starburst galaxies at z~1.

WFXT will carry out three extragalactic surveys, providing calibrated data products released with no proprietary period.

  • a WIDE survey will cover most of the extragalactic sky (~20,000 deg2) at ~500 times the sensitivity, and twenty times better angular resolution of the ROSAT All Sky Survey;
  • a MEDIUM survey will map ~3000 deg2 to deep Chandra or XMM - COSMOS sensitivity;
  • a DEEP survey will probe ~100 deg2, or ~1000 times the area of the Chandra Deep Fields, to the deepest Chandra sensitivity.

Comparison of WFXT to other missions

Sensitivity/area comparison of WFXT to other missions

The discovery space (grasp = sensitivity X area) of WFXT far exceeds any current or planned mission.

WFXT Survey Details

Table of WFXT survey details

WFXT will detect millions of AGN and hundreds of thousands of clusters.

The WFXT mission is scientifically broad, as the survey data will

  • provide a description of the cosmic evolution and cycle of baryons
  • map the large scale structure of the Universe
  • constrain and test cosmological models and fundamental physics (e.g., the nature of Dark Matter, Dark Energy and gravity)
  • determine the black hole accretion history to early epochs and its intimate link with galaxy formation
  • provide an unprecedented view of nearby galaxies including our own.

WFXT is not only a path finder for other missions, its large collecting area allows direct physical characterization of a large fraction of sources (AGN and Clusters) via X-ray spectroscopy with no need of follow-up observations. Synergy with other missions further enhances its scientific potential and breadth.

Like the Sloan Digital Sky Survey, all WFXT data will become public through a series of annual data releases that will constitute a vast scientific legacy for decades.


WFXT has received support from Johns Hopkins University Applies Physics Laboratory to develop the conceptual study, as well additional funding from NASA Marshall Space Flight Center and Agenzia Spaziale Italiana (Italian Space Agency) to develop the mirror design. The total cost of the mission, from conceptual study through post-launch support (including Education and Public Outreach) is ~$640-690 M (US). Following two requests for information, the WFXT team is currently awaiting the results from the US National Academy of Sciences 2010 Astronomy and Astrophysics Decadal Survey and is poised to take advantage of new mission opportunities from NASA.

Copyright (c) 2001-2010 Johns Hopkins University All Rights Reserved.
This work acknowledges the support of NASA of the U.S. Government.