The GEMS photoelectric x-ray polarimeters

Black, J. K.; Deines‐Jones, P.; Hill, J. E.; Iwahashi, T.; Jahoda, K.; Kaaret, Philip; Kallman, T. R.; Martoff, C. J.; Prieskorn, Zachary; Swank, J. H.; Tamagawa, Toru

doi:10.1117/12.857736

Cited by 19 publications

(27 citation statements)

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“…However, for large regions of the parameter space, the approximate degeneracy between the black hole spin a and the deviation parameter 3 will make it difficult to distinguish between GR and non-GR models. The GEMS mission achieves the best sensitivity (∼1% polarization degree for a mCrab source) with a photoelectric effect polarimeter operating over the 2-10 keV energy range (Black et al 2010). GEMS would be able to detect the polarization of the X-ray emission from bright X-ray binaries like Cyg X-1 and GRS 1915 + 105 with an excellent signal-to-noise ratio.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…In the next few years, it may become possible to confront GR with new types of experimental data. In this paper, we discuss non-imaging spectropolarimetric X-ray observations of stellar mass black holes enabled by a mission like GEMS (Gravity and Extreme Magnetism SMEX) (Black et al 2010) or BEST (Black Hole Evolution and Space Time) (Krawczynski et al 2012). Other electromagnetic observations with the potential to test strong gravity GR include pulsar timing observations (Wex & Kopeikin 1999), radio imaging of supermassive black holes (e.g., Doeleman et al 2009), time-resolved X-ray observations of the Fe Kα fluorescent line from galactic and extragalactic black holes (e.g., Reynolds & Nowak 2003;Guainazzi 2009), and the observation of stars orbiting the supermassive black hole at the center of the Milky Way Merritt et al 2010).…”

Section: Introductionmentioning

confidence: 99%

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Tests of General Relativity in the Strong-Gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

Krawczynski

2012

ApJ

105

114

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Although general relativity (GR) has been tested extensively in the weak-gravity regime, similar tests in the strong-gravity regime are still missing. In this paper, we explore the possibility to use X-ray spectropolarimetric observations of black holes in X-ray binaries to distinguish between the Kerr metric and the phenomenological metrics introduced by Johannsen & Psaltis (which are not vacuum solutions of Einstein's equation) and thus to test the no-hair theorem of GR. To this end, we have developed a numerical code that calculates the radial brightness profiles of accretion disks and parallel transports the wave vector and polarization vector of photons through the Kerr and non-GR spacetimes. We used the code to predict the observational appearance of GR and non-GR accreting black hole systems. We find that the predicted energy spectra and energy-dependent polarization degree and polarization direction do depend strongly on the underlying spacetime. However, for large regions of the parameter space, the GR and non-GR metrics lead to very similar observational signatures, making it difficult to observationally distinguish between the two types of models.

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Section: Summary and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Tests of General Relativity in the Strong-Gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

Krawczynski

2012

ApJ

105

114

View full text Add to dashboard Cite

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“…Another technique by Sakurai et al (2004) exploits CCDs to detect the UV scintillation images of photoelectron tracks in a Capillary Gas Proportional Counter. The photoelectric effect in a gas is also exploited in time projection chambers for GEMS (Black et al 2010). A high quantum efficiency is obtained at the expense of imaging, while its 1D imaging capability is very much blurred by inclined penetration (see Section 2), due to focusing, in astronomical implementations (Jahoda 2010) with a consequently much larger background.…”

Section: Configurationmentioning

confidence: 99%

The Imaging Properties of the Gas Pixel Detector as a Focal Plane Polarimeter

Fabiani

Costa

Monte

et al. 2014

ApJS

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X-rays are particularly suited to probing the physics of extreme objects. However, despite the enormous improvements of X-ray astronomy in imaging, spectroscopy, and timing, polarimetry remains largely unexplored. We propose the photoelectric polarimeter Gas Pixel Detector (GPD) as a candidate instrument to fill the gap created by more than 30 yr without measurements. The GPD, in the focus of a telescope, will increase the sensitivity of orders of magnitude. Moreover, since it can measure the energy, the position, the arrival time, and the polarization angle of every single photon, it allows us to perform polarimetry of subsets of data singled out from the spectrum, the light curve, or an image of the source. The GPD has an intrinsic, very fine imaging capability, and in this work we report on the calibration campaign carried out in 2012 at the PANTER X-ray testing facility of the Max-PlanckInstitut für extraterrestrische Physik of Garching (Germany) in which, for the first time, we coupled it with a JET-X optics module with a focal length of 3.5 m and an angular resolution of 18 arcsec at 4.5 keV. This configuration was proposed in 2012 aboard the X-ray Imaging Polarimetry Explorer (XIPE) in response to the ESA call for a small mission. We derived the imaging and polarimetric performance for extended sources like pulsar wind nebulae and supernova remnants as case studies for the XIPE configuration and also discuss possible improvements by coupling the detector with advanced optics that have a finer angular resolution and larger effective areas to study extended objects with more detail.

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“…181]), an IXO-type highthroughput soft X-ray observatory (measurement of the spins of a sample of SMBHs through Fe K-α observations) [182], a GEMS-type high-sensitivity X-ray polarimeter (geometry of accretion disk coronae and magnetic field structure in jets) [183], and the next-generation Cherenkov Telescope Array (time resolved observations of blazars and mapping of the γ-ray emission from radio galaxies) [184].…”

Section: Discussionmentioning

confidence: 99%

Active galactic nuclei — the physics of individual sources and the cosmic history of formation and evolution

Krawczynski

Treister

2013

Front. Phys.

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In this paper we give a brief review of the astrophysics of active galactic nuclei (AGN). After a general introduction motivating the study of AGNs, we discuss our present understanding of the inner workings of the central engines, most likely accreting black holes with masses between 10 6 and 10 10 M . We highlight recent results concerning the jets (collimated outflows) of AGNs derived from X-ray observations (Chandra) of kpc-scale jets and γ-ray observations of AGNs (Fermi, Cherenkov telescopes) with jets closely aligned with the lines of sight (blazars), and discuss the interpretation of these observations. Subsequently, we summarize our knowledge about the cosmic history of AGN formation and evolution. We conclude with a description of upcoming observational opportunities. MotivationActive galactic nuclei (AGNs) are galaxies that harbor supermassive black holes (SMBHs) of a few million to a few billion solar masses. Whereas it seems likely that all galaxies contain one or more supermassive black holes [1,2], the black holes in AGNs give rise to spectacular observational consequences because they accrete matter and convert the gravitational energy of the accreted matter (and possibly also the rotational energy of the black hole) into mechanical and electromagnetic energy. A few of the most salient motivations for the study of AGNs are: and statistical characterization. The study of AGNs in the nearby Universe shows that the diversity of AGNs can be understood as resulting from observing a smaller number of basic AGN types from different viewing angles (see Section 3.1).Accretion Physics: AGNs are powered by the accretion of magnetized plasma. Studies of AGN accretion flows complement studies of other accretion flows in astrophysics: accretion onto protostars and stars, accretion onto compact stellar remnants (neutron stars and stellar mass black holes), and the accretion that powers gamma-ray bursts. One goal of the studies of AGN accretion flows is to provide a physical explanation of the different types of AGNs and their states in terms of the nature of their accretion flows and environments (see Section 3.3).Role in Eco-Systems: AGNs play an important role for galactic and galaxy cluster eco-systems, i.e. their mechanical and electromagnetic power contributes to the heating of the interstellar and intracluster medium, and thus influences the star formation of the host systems (see Section 2.4).History through Cosmic Time: Deep radio, IR, optical and X-ray observations of AGNs have provided us with a wealth of information about the cosmic history of the formation and growth of supermassive black holes and the evolution of AGNs. Related areas of research are to clarify the role of AGNs in re-ionizing the intergalactic medium, and to explain the correlation between black hole masses and the properties of the host galaxy observed in the local Universe (see Sections 4 & 5).Fundamental Physics: On the most fundamental level, AGNs allow us to test the theory of general relativity (GR). GR's no-hair theor...

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The GEMS photoelectric x-ray polarimeters

Cited by 19 publications

References 0 publications

Tests of General Relativity in the Strong-Gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

Tests of General Relativity in the Strong-Gravity Regime Based on X-Ray Spectropolarimetric Observations of Black Holes in X-Ray Binaries

The Imaging Properties of the Gas Pixel Detector as a Focal Plane Polarimeter

Active galactic nuclei — the physics of individual sources and the cosmic history of formation and evolution

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