Highlights and discoveries from theChandraX-ray Observatory

Abstract

Within 40 years of the detection of the first extra-solar x-ray source in 1962, NASA's Chandra X-ray Observatory has achieved an increase in sensitivity of 10 orders of magnitude, comparable to the gain in going from naked-eye observations to the most powerful optical telescopes over the past 400 years. Chandra is unique in its capabilities for producing sub-arcsecond x-ray images with 100-200 eV energy resolution for energies in the range 0.08 < E < 10 keV, locating x-ray sources to high precision, detecting extremely faint sources, and obtaining high-resolution spectra of selected cosmic phenomena. The extended Chandra mission provides a long observing baseline with stable and well-calibrated instruments, enabling temporal studies over timescales from milliseconds to years. In this report we present a selection of highlights that illustrate how observations using Chandra, sometimes alone, but often in conjunction with other telescopes, have deepened, and in some instances revolutionized, our understanding of topics as diverse as protoplanetary nebulae; massive stars; supernova explosions; pulsar wind nebulae; the superfluid interior of neutron stars; accretion flows around black holes; the growth of supermassive black holes and their role in the regulation of star formation and growth of galaxies; impacts of collisions, mergers, and feedback on growth and evolution of groups and clusters of galaxies; and properties of dark matter and dark energy.

Extremal rotating black holes in the near-horizon limit: Phase space and symmetry algebra

“…Starting with the most general diffeomorphism generator χ, we highlight conditions singling out (3), which is the basic object both in construction of the phase space G[{F }] and the algebra (8). The following six requirements uniquely fix χ given in (3). These requirements are mainly aimed at providing a rationale for selecting the diffeomorphism which was found by an ansatz.…”

Fifteen years of Chandra operation: scientific highlights and lessons learned

“…A comprehensive review [1] has recently appeared in the literature. Here we present a small sample of recent highlights.…”

Extreme Kerr black hole microstates with horizon fluff

“…We showed how the horizon fluff idea can be worked through for the 4D extremal Kerr black hole. Our analysis expands upon the Kerr/CFT analysis [13] in three important ways: (1) our symmetry algebra is defined over the whole extremal Kerr geometry and not only in the near horizon region; (2) we have introduced the extremal Kerr phase space, our symmetries are symplectic (and not just asymptotic) and, (3) besides the Virasoro, we have a current algebra and our symmetry generator diffeomorphisms are all along the azimuthal angle ∂ φ . Our preliminary analysis shows that similar features can be extended to other extremal black holes in higher dimensions, in particular to the class discussed in [32].…”

“…Existence of rotating black holes in the sky, besides the notable gravity wave detection by LIGO [1], is backed by many different advanced x-ray astronomy observations [2]. The Kerr geometry [3] provides a very good description of these black holes and is specified by two parameters, mass and angular momentum (spin).…”