X-ray spectropolarimetric measurements of the Kerr metric

Abstract

It is thought that the spacetime geometry around black hole candidates is described by the Kerr solution, but an observational confirmation is still missing. Today, the continuum-fitting method and the analysis of the iron Kα line cannot unambiguously test the Kerr paradigm because of the degeneracy among the parameters of the system, in the sense that it is impossible with current X-ray data to distinguish a Kerr black hole from a non-Kerr object with different values of the model parameters. In this paper, we study the possibility of testing the Kerr nature of black hole candidates with X-ray spectropolarimetric measurements. Within our simplified model that does not include the effect of returning radiation, we find that it is impossible to test the Kerr metric and the problem is still the strong correlation between the spin and possible deviations from the Kerr geometry. Moreover, the correlation is very similar to that of the other two techniques, which makes the combination of different measurements not very helpful. Nevertheless, our results cannot be taken as conclusive and, in order to arrive at a final answer, the effect of returning radiation should be properly taken into account.

Unexpected synthesis of 1,3,5-triarly-1,5-diketones from aryl ketones via di-enamine mechanism

“…The aryl ketones might be activated via di-enamine intermediate 5, which further reacted with 1a to form 6, and the transformation of 6 to 7 might be a synergetic process. 8 Fortunately, the key intermediate 7c was separated and characterized by 1 H NMR and Mass spectra (MW 366.67), which was found to be easily converted to 3a catalyzed by acid (See Supplementary data). Furthermore, acetohydrazone of aryl ketone 9 could not react with substrate 1a and aromatic aldehyde under the same catalytic conditions, further confirming the enamine activation of aryl ketones (Scheme 5, (1)).…”

Emerging Applications of Elemental 2D Materials

“…[138] Arsenene has been predicted to be a promising candidate for sensing NO, NO 2, and SO 2 , as the molecules interact strongly with the elemental 2D material and can create a measureable and detectable change in magnetic moment. [157,171] Semimetal 2D materials such as silicone and germanene provide for an interesting platform for sensing, as bandgaps can be opened and controlled specifically from molecular adsorption. For instance, DFT results predict that germanene is a candidate for gas sensing of NO and NH 3 due to moderate activation energies for chemisorption (−0.51 and Adv.…”

Synthesis and Properties of A Low Melting Point Phthalonitrile Resin Containing High Density Nitrile Groups

“…Because of the high melting point and poor processability of the first generation of phthalonitrile monomers, flexible aromatic ether segments were introduced into the molecular structure of the monomers by Keller at Naval Laboratory (NRL). [18] At present, aliphatic aromatic ether, [19,20] poly(ether imide), [21] poly-(arylene ether ketone), [22][23][24] poly-(arylene ether) [25][26][27] and poly-(arylene ether nitrile) [28] have been reported. These monomers are usually prepared by the reaction of activated dihalogenated aromatic hydrocarbons and appropriate proportions of bisphenols to form phenolic intermediates, and then end-capped with 4-nitrophthalonitrile.…”