Mission Overview

AXIS (Advanced X-ray Imaging Satellite) is a NASA Probe Mission Concept to be the premier high angular resolution X-ray mission of the mid-2020s. The need for sub-arc sec resolution in astrophysics is evident across the entire electromagnetic spectrum. It is essential for resolving the critical physical scales of virtually all classes of objects and for extending such studies to the highest redshift. AXIS will follow in the footsteps of the spectacularly successful Chandra X-ray Observatory with similar or higher angular resolution and ~10x Chandra count rates.

Read the full Probe Mission Concept Proposal here.

Science Goals

Galaxies Over Cosmic Time

Galaxies are complex systems that evolve dramatically over cosmic time. Their critical constituents – stars, gas and dust, supermassive black holes and dark matter – are strongly coupled to one another and all have critical parameters that can only be studied in the X-ray band. A detailed study of them to high redshifts requires both high angular resolution and high sensitivity.

Feedback in Galaxies

Theoretical models of galaxy formation require physics beyond just gravity and hydrodynamics. This is called “feedback”: the influence of the objects themselves on their formation. For massive galaxies, it is thought that the main cause of feedback is the influence of the supermassive black hole on star formation, either expelling gas from the galaxy or preventing it from falling in.

Black Hole Strong Gravity

If the geometry is just right, gravitational lensing by a foreground galaxy can produce several images of a background quasar, separated by a few arc-seconds or less. Each image then flickers due to microlensing by individual stars within the lensing galaxy. A statistic analysis of this flicker reveals information about the micro-arcsecond scale structures of the inner accretion disk.

Dual AGN

The general theory of structure formation predicts that mergers are a major component of galaxy growth and evolution. It has long been predicted that when the galaxies merge, so should their black holes. Little information is known about the occurrence rate of dual AGN for a large sample of objects covering a wide range in mass, luminosity and nature of the host galaxy.

The High-Redshift Universe

Only a small number of X-ray AGNs have been directly detected beyond z>5. AXIS has the potential to generate much larger samples of z>5 AGNs, allowing the study of how the AGN luminosity function changes at high redshifts and comparison with the star formation history. This is a key measurement in understanding the co-evolution of black holes and their host galaxies.

Observatory Science

We hope the community will join in the fun! This includes the detailed study of star clusters, resolving supernova remnants in nearby galaxies, the astrophysics of jets, pulsar wind nebulae, star formation regions in the local group, cluster cooling fronts, galaxy interactions, bubbles in clusters, ram pressure stripping of galaxies in groups and clusters and beyond.


Mirror. In order accomplish the axis science objectives, the x-ray mirror will combine large throughput with high angular resolution. thin shell mirror technology being developed at nasa's goddard space flight center holds the promise of providing the needed combination of properties at a reasonable mass and cost.

Detector. The focal plane detector will be a ccd or related device. the relatively modest 15’ field of view translates to an active focal plane area of 3 cm x 3 cm. smaller pixels will substantially reduce the particle background through superior multi-pixel filtering of the larger charge clouds produced by cosmic rays and significantly reduce pile-up from bright point sources.


For details about AXIS technology and science, look to these presentations.

AXIS Presentation at HEAD 2017 - Erin Kara and Eric Miller

Binary Supermassive Black Holes: Importance for AXIS - Mike Koss

Jets and Lobes above z=4 - Andy Fabian

Galaxy Science with AXIS - Edmund Hodges-Kluck

How galaxy clusters connect to the Cosmic Web - Maxim Markevitch

AXIS: resolving the gravitational sphere of influence of SMBHs - Helen Russell

The Physics of AGN Feedback in Clusters of Galaxies - Chris Reynolds

Compact Objects with AXIS - Erin Kara

AXIS Observations of AGN Winds - Francesco Tombesi

Microlensing Quasars with AXIS - George Chartas

Galactic Foreground Polarization and Dust Halos - Lynne Valencic

Looking at the heart of the feedback process in clusters of galaxies - Andy Fabian

Optics for AXIS - Will Zhang

Detectors for AXIS - Eric Miller

simx: A General-Purpose X-ray Event Simulator - Randall Smith

AXIS Study Plan Implentation - Andy Ptak

The AXIS Team

PI: Richard Mushotzky

Our first team meeting at the University of Maryland, College Park. June 14-15, 2017.

List of Attendees (left to right): Mike Lowenstein, Andy Ptak, Randall Smith, Lynne Valencic, George Chartas, Will Zhang, Maxim Markevitch, Richard Mushotzky, Brian Morsony, Francesco Tombesi, Rob Petre, Eric Miller, Helen Russell, Chris Reynolds and Erin Kara.

Not Pictured: Amy Barger, David Burrows, Andy Fabian, Catherine Grant, Edmund Hodges-Kluck, Mike Koss, Jon Miller, John Mulchaey and Hiroya Yamaguchi.

Contact Us

If you have ideas, suggestions or comments for AXIS, please tell us what you think!