Transcript Source Variability - Center for Astrophysics and Space

Webster Cash
University of Colorado
MAXIM
The Micro-Arcsecond X-ray Imaging Mission
Collaborators
• Ann Shipley, Randy McEntaffer, Steve Osterman
at CU
• Keith Gendreau, Nick White – Goddard
• Marshall Joy – Marshall
• Dennis Gallagher, Mike Leiber – Ball
• The Maxim Team – http://maxim.gsfc.nasa.gov
Maxim Heritage
• 1995 – Future Concepts for X-ray Astronomy Chosen by Competition
– Tananbaum, White, Gorenstein, Cash
• 1996 – Leicester Meeting -- Observatories for 21st Century
– Con-X and Xeus emerged as leaders
– First Public Presentation on X-ray Interferometry (Deeper into 21st)
• 1998 – Formation of Maxim Committee
– Reviewed Feasibility
– Set Imaging of Black Hole as Long Term Goal
• 1999 – Creation of Fringes
– Support from NASA Institute for Advanced Concepts
• 2000 – Support from SEU and Decadal Committee
Galaxies
22
AGN
Jets
SNR
18
Log Diameter (cm)
Galactic Extra-Galactic
Star
Clusters
20
Clusters of
Galaxies
Interstellar
16
AGN BLR
Sne
14
Interacting
Binaries
12
Compact
XRB
Orbits
Stellar Coronae
10
AGN
Event
Horizons
GRB
Afterglow
CV
XRB Disks
8
6
NS Disks
0
1
2
3
4
5
6
Log Distance (pc)
7
8
9
10
10
9
Clocks
Earth
GPB
8
Jupiter
Orbit
Binary Pulsar
Log(Rc2/GM)
7
Eclipse
Sun
LIGO
6
5
Lens
Galaxies
4
Sirius B
3
2
VLBI
BLR M87
Maxim Pathfinder
Strong Gravity
1
Event Horizon
0
6
4
2
0
Crab
CygX-1
Maxim
SgrA*/M87
LISA Con-X
-2
-4
-6
Log Resolution (arcsec)
-8
-10
-12
Capella 0.1”
Capella 0.01”
Capella 0.001”
Capella 0.0001”
Capella 0.00001”
Capella 0.000001”
AR Lac
Simulation @ 100mas
NASA/Dana Berry
AGN Accretion Disk
Simulations @ 0.1mas
Courtesy of C. Reynolds, U. Maryland
Need Resolution and Signal
If we are going to do this, we need to support
two basic capabilities:
• Signal
• Resolution
X-ray Sources Are Super Bright
Example:
Mass Transfer Binary
1037ergs/s from 109cm object
That is ~10,000L from 10-4A = 108 B
where B is the solar brightness in ergs/cm2/s/steradian
Brightness is a conserved quantity and is the measure of visibility
for a resolved object
Note: Optically thin x-ray sources can have
very low brightness and are inappropriate
targets for interferometry.
Same is true in all parts of spectrum!
Artist’s impression of Cyg X-1 (NASA)
My Impression
Status of X-ray Optics
• Modest Resolution
– 0.5 arcsec telescopes
– 0.5 micron microscopes
• Severe Scatter Problem
– Mid-Frequency Ripple
• Extreme Cost
– Millions of Dollars Each
– Years to Fabricate
Pathlength Tolerance Analysis at Grazing Incidence
A1
B1 
sin 
B2  B1cos2 
A2
OPD  B1  B 2 



B1
A1 & A2 in Phase Here
B2

 1  cos 2 
 2 sin 
sin 
If OPD to be < /10 then 


20 sin 

C
d Baseline  
S2
S1

d  focal  

20 sin  cos 

20 sin 2 
A Simple X-ray Interferometer
Flats
Detector
Wavefront Interference
=s (where s is fringe spacing)
s
d/L
L
s
d
Optics
Each Mirror Was Adjustable
From Outside Vacuum
System was covered by thermal shroud
X-ray Fringes
0.5keV
Gendreau, October 2002
1.25keV
Cash et al March 1999
Flats Held in Phase
Sample Many Frequencies
As More Flats Are Used
Pattern Approaches Image
2
12
4
8
16
32
On the left is the probability distribution function for two sources in the same
field of view. The central source has an energy half that of the source that is
displaced to the lower left. The image on the right shows 9000 total events for
this system with the lower energy source having twice the intensity of the higher
energy source. Even though the higher energy source is in the first maxima of
the other, the two can still be easily distinguished.
Clockwise from upper left: Probability distribution; 100 photons randomly plotted; 9000
photons; and 5000 photons.
Stars
Simulation with Interferometer
Sun with SOHO
Maxim
“The Black Hole Imager”
200
M
CONSTELLATION
BORESIGHT
10
KM
COLLECTOR
SPACECRAFT
(32 PLACES
EVENLY SPACED)
CONVERGER
SPACECRAFT
5000
KM
DETECTOR
SPACECRAFT
0.1mas Resolution
10,000cm2 Effective Area
0.4-7.0 keV
Maxim Pathfinder
100mas Resolution
100cm2 Effective Area
0.4-2.0keV + 6keV
Two Spacecraft
Formation Flying at
450km Separation
MAXIM Pathfinder Stowed –
Internal Metrology Not Shown
MAXIM Pathfinder in Deployed
Configuration
Primary and Secondary Optical
Ring Layout
Detailed View of Primary and
Secondary Optical Rings
Effect of Tilt
0.25
0.1
Percent encircled energy
0.12
0.1
Percent encircled energy
Percent encircled energy
0.12
0.08
0.06
0.04
0.08
0.06
0.04
0.02
0.02
0
0.05 0.1 0.15 0.2 0.25 0.3 0.35
Angular distance from peak (mas)
-6
-4
-2
0.15
0.1
0.05
0
0
0
0.2
0.1
0.2
0.3
0.4
0.5
0.6
Angular distance from peak (mas)
0.7
-3
-3
-2
-2
-1
-1
0
0
1
1
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Angular distance from peak (mas)
0
2
2
2
4
3
3
6
-3
-6
-4
-2
0
2
4
Angular coordinates (mas)
6
-2
-1
0
1
2
Angular coordinates (mas)
3
-3
-2
-1
0
1
2
Angular coordinates (mas)
3
MAXIM Structural Dynamics
Model
-4
Magnitude response TF (lbf input/rad output)
10
-6
10
-8
10
-10
10
-12
10
0
10
1
2
10
10
• Frequency response curve shows first 50 structural modes
• Damping of 0.5% assumed for all modes
• Transfer function from RW force inputs to x and y tilt (2 curves) at focal
plane - only largest TF in tip/tilt shown.
• Thermal, RW and thruster disturbances to structural stability
3
10
Frequency (Hz)
First 5 Structural Mode Shapes
Tackling Full Maxim --- The Periscope Configuration
Keeps beam pointed
in constant direction
like thin lens
To focus

Parallel to Source Direction
Reduces Sensitivity to Baseline
Each Periscope in the array is held to /20sin  10m
Periscopes allow for delay in each
channel. Can sample full UV plane.
focus
Integrated Mission Design Center
Goddard Space Flight Center
Delta IV
5m X 14.3m fairing
Delta IV Heavy
5m X 19.1m fairing
Propulsion/Hub SpaceCraft
Sta. 7600
Delta IV
5m X 14.3m fairing
Sta. 4300
Hub SpaceCraft/Detector SpaceCraft
C.G. Sta. 2500
Sta. 1550
Propulsion/Hub SpaceCraft
P/L Sta. 0.00
7/6/2015
40
Mission Sequence
1 km
Science Phase #1
Low Resolution
Launch
Science Phase #2
High Resolution
200 km
20,000 km
Transfer Stage
Component Layout
Detector
Solar Array (4.5 m2)
Comm Antenna
(Ground/SpaceCraft 0.5 m)
Thermal Shade (2.3 m2)
Comm Antenna
Comm Antenna
(S/C to S/C 0.3 m)
(Ground/SpaceCraft 0.5 m)
CCD Electronics
LOS laser receiver
CCD Camera
Hub/Detector Sensor
Configuration
Hub S/C
Laser Beacon illuminates
Detector S/C
Super Star Tracker
centers on Laser Beacon
Detector S/C
Super gyros
hold inertial
attitude
Laser Detector measures range
by time-of-flight of reflected
laser beam
Normal Star Tracker
places Laser Beacon
against fixed stars
Coarse Ranging by omni RF comm link
Reflector Cube reflects
laser beam back to Hub
for ranging
Status:
X-ray Interferometry in NASA Planning
McKee-Taylor Report
National Academy Decadal Review of Astronomy
Released May 19, 2000
Prominently Recommends Technology Development
Money for X-ray Interferometry
Structure and Evolution of the Universe (SEU) Roadmap
Major Goal of the “Beyond Einstein” Initiative
Near Term Technology Program
“X-ray Roadmap” to Image a Black Hole
Imaging
ROSAT
Einstein
Chandra
1000 times finer
imaging
Optimize
MAXIM
Parameters
100-1000 cm2
0.5 arc sec
Constellation-X
MAXIM
Pathfinder
100 cm2
2 m baseline
100 marc sec
Spectroscopy
ASCA
RXTE
Do they
exist?
XMM
Astro-E
Where are
they?
2000
Million times
finer imaging
MAXIM
1000 cm2
100-1000 m baseline
100 nas
3 m2
Indirect imaging
via spectroscopy
Conditions in
the inner disk
2008
Spectrally
Resolved
X-ray
Interferometry
Demonstration
Black hole
Imager!
2014
2020