Testing general relativity with the reflection spectrum of the supermassive black hole in 1H0707−-495

Recently, we have extended the X-ray reflection model relxill to test the spacetime metric in the strong gravitational field of astrophysical black holes. In the present Letter, we employ this extended model to analyze XMM-Newton, NuSTAR, and Swift data of the supermassive black hole in 1H0707-495 and test deviations from a Kerr metric parametrized by the Johannsen deformation parameter $\alpha_{13}$. Our results are consistent with the hypothesis that the spacetime metric around the black hole in 1H0707-495 is described by the Kerr solution.Comment: 10 pages, 7 figures. v2: refereed versio

Public Release of RELXILL_NK: A Relativistic Reflection Model for Testing Einstein's Gravity

We present the public release version of relxill_nk, an X-ray reflection model for testing the Kerr hypothesis and general relativity. This model extends the relxill model that assumes the black hole spacetime is described by the Kerr metric. We also present relxilllp_nk, the first non-Kerr X-ray reflection model with a lamppost corona configuration, as well as all other models available in the full relxill_nk package. In all models the relevant relativistic effects are calculated through a general relativistic ray-tracing code that can be applied to any well-behaved, stationary, axisymmetric, and asymptotically flat black hole spacetime. We show that the numerical error introduced by using a ray-tracing code is not significant as compared with the observational error present in current X-ray reflection spectrum observations. In addition, we present the reflection spectrum for the Johannsen metric as calculated by relxill_nk.Comment: 15 pages, 8 figures. v2: refereed version. Code and documentation available at http://www.physics.fudan.edu.cn/tps/people/bambi/Site/RELXILL_NK.html and at http://www.tat.physik.uni-tuebingen.de/~nampalliwar/relxill_nk

Testing the Kerr metric with X-ray Reflection Spectroscopy of Mrk 335 Suzaku data

Einstein's gravity has undergone extensive tests in the weak field gravitational limit, with results in agreement with theoretical predictions. There exist theories beyond general relativity (GR) which modify gravity in the strong field regime but agree with GR in the weak field. Astrophysical black holes are believed to be described by the Kerr metric and serve as suitable candidates to test strong gravity with electromagnetic radiation. We perform such a test by fitting one Suzaku dataset of the narrow-line Seyfert 1 (NLS1) galaxy Mrk 335 with X-ray reflection spectroscopy, using the Johannsen metric to model the black hole spacetime and test for deviations from Kerr. We find the data is best modeled with a hybrid model that includes both partial covering absorption and a reflection component. This is the first time such a model has been proposed for a high-flux (low reflection) Mrk 335 dataset. We constrain the Johannsen deformation parameter $\alpha_{13}$ to $-1.50.8$, and the $\alpha_{22}$ parameter to $-0.40.7$, both at the 99% confidence level. Although additional solutions at large deviations from the Kerr metric show statistical similarity with the ones above, further analysis suggests these solutions may be manifestations of uncertainties beyond our control and do not represent the data. Hence, our results are in agreement with the idea that the supermassive compact object at the center of Mrk 335 is described by the Kerr metric.Comment: 13 pages, 9 figures. v2: refereed versio

X-ray Reflection Spectroscopy of the Black Hole GX 339-4: Exploring the Hard State with Unprecedented Sensitivity

We analyze {\it simultaneously} six composite {\it RXTE} spectra of GX 339--4 in the hard state comprising 77 million counts collected over 196 ks. The source spectra are ordered by luminosity and spanthe range 1.6\% to 17\% of the Eddington luminosity. Crucially, using our new tool {\tt pcacorr}, we re-calibrate the data to a precision of 0.1\%, an order of magnitude improvement over all earlier work. Using our advanced reflection model {\tt relxill}, we target the strong features in the component of emission reflected from the disk, namely, the relativistically-broadened Fe K emission line, the Fe K edge and the Compton hump. We report results for two joint fits to the six spectra: For the first fit, we fix the spin parameter to its maximal value ($a_*=0.998$) and allow the inner disk radius $R_{\rm in}$ to vary. Results include (i) precise measurements of $R_{\rm in}$, with evidence that the disk becomes slightly truncated at a few percent of Eddington; and (ii) an order-of-magnitude swing with luminosity in the high energy cutoff, which reaches $>890$ keV at our lowest luminosity. For the second fit, we make the standard assumption in estimating spin that the inner edge of the accretion disk is located at the innermost stable circular orbit ($R_\mathrm{in} = R_\mathrm{ISCO}$) and find $a_* = 0.95^{+0.03}_{-0.05}$ (90\% confidence, statistical). For both fits, and at the same level of statistical confidence, we estimate that the disk inclination is $i = 48\pm 1$ deg and that the Fe abundance is super-solar, $A_\mathrm{Fe} = 5\pm1$.Comment: Accepted for publication in ApJ, 20 pages, 13 figure

Nicht formal Qualifizierte arbeitsplatznah weiterbilden: Konzeption, Umsetzung und Implementierung innovativer Lernformate

Der Open-Access-Leitfaden stellt ein innovatives Lernformat für nicht formal Qualifizierte vor und gibt Arbeitsmarkt- und Bildungsakteuren einen Überblick über die Etablierung auf dem regionalen Bildungsmarkt. Die Lernangebote aus dem Projekt Pro-up fördern berufliche Kompetenzen durch Lernprozessbegleitung und basieren auf dem kombinierten Einsatz bei Bildungsdienstleistern und Betrieben. Nach einer Einführung in Hintergründe und Entstehung stellen die Autoren das Konzept vor und zeigen anhand von Praxisbeispielen aus einer Pilotphase, wie die Lernarrangements an Branchen- und Berufsspezifika angepasst werden können. Didaktische Gestaltung, Aufbau und Zielgruppe der Lernsettings sind Themen weiterer Kapitel. Ausführlich wird erläutert, wie die Angebote auf dem regionalen Bildungsmarkt etabliert werden können und welche Anforderungen, besonders für Weiterbildungsanbieter, mit dem Perspektivwechsel vom Seminaranbieter zum Weiterbildungsmanager verbunden sind. Das Konzept wurde im Projekt Pro-up entwickelt und bundesweit in fünf Arbeitsagenturbezirken erprobt. Das Projekt "Innovative Weiterbildungsangebote für nicht formal Qualifizierte" (Pro-up) wurde durch das Bundesministerium für Bildung und Forschung (BMBF) gefördert und vom Bundesinstitut für Berufsbildung (BIBB) sowie der Bundesagentur für Arbeit (BA) begleitet

On Estimating the High-Energy Cutoff in the X-ray Spectra of Black Holes via Reflection Spectroscopy

The fundamental parameters describing the coronal spectrum of an accreting black hole are the slope $\Gamma$ of the power-law continuum and the energy $E_{cut}$ at which it rolls over. Remarkably, this parameter can be accurately measured for values as high as 1 MeV by modeling the spectrum of X-rays reflected from a black hole accretion disk at energies below 100 keV. This is possible because the details in the reflection spectrum, rich in fluorescent lines and other atomic features, are very sensitive to the spectral shape of the hardest coronal radiation illuminating the disk. We show that fitting simultaneous NuSTAR (3-79 keV) and low-energy (e.g., Suzaku) data with the most recent version of our reflection model RELXILL, one can obtain reasonable constraints on $E_{cut}$ at energies from tens of keV up to 1 MeV, for a source as faint as 1 mCrab in a 100 ks observation.Comment: Accepted for publication in ApJL, 6 pages, 5 figure