EVIDENCE OF ACCRETION-GENERATED X-RAYS IN THE YOUNG ...

3.2.1 The High Resolution Mirror Assembly
The Chandra X-ray Observatory’s telescope consists of four pairs of nested iridium-
coated mirrors (Fig. 10) known as the High Resolution Mirror Assembly (HRMA).
The mirrors of an X-ray telescope are cylindrical in shape, and Chandra’s mirrors
have diameters that range from 0.65 to 1.23 meters. A spherical mirror, such as
that found in an optical telescope, would be unable to reflect and focus X-ray pho-
tons since X-ray wavelengths are on the order of the size of the atomic/molecular
spacing of the material that makes up the mirror; i.e., the photons would typically
pass through the mirror. To overcome this problem, mirrors make use of “grazing
incidence” in which the surfaces of the mirrors are nearly (within a couple of degrees
of) parallel to the path of the incoming X-ray photons. The photons are first in-
tercepted by four nested mirrors that have a slight parabolic curvature. Afterwards,
the photons are intercepted by a second set of mirrors, located behind the first set,
which have a slight hyperbolic curvature. In e↵ect, these mirrors gradually alter the
trajectory of the photons, requiring the telescope to have a long focal length. As a
result, the detectors have to be placed a large distance from the mirror assembly –
the distance from the Central Aperture Plate (CAP), which separates the parabolic
and hyperbolic mirrors of Chandra, to the focal point of the HRMA is 10.23 meters.
As with all telescopes, light gathering power and resolution are two of the major
design concerns. How e↵ectively the mirrors are able to reflect and focus incoming X-
ray photons depends on the incoming X-ray photon energy as well as the grazing angle
of the mirrors. Due to the cylindrical shape of Chandra’s mirrors, the overall e↵ective
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