Skip to main content

REMAIN SOME POSSIBILITIES FOR ALTERNATIVE THEORIES OF GRAVITY?

Image: Numerical simulations of the gravitational waves emitted by the inspiral and merger of two black holes. The colored contours around each black hole represent the amplitude of the gravitational radiation; the blue lines represent the orbits of the black holes and the green arrows represent their spins. Credit: C. Henze/NASA Ames Research Center

The observation of gravitational-wave signal by LIGO and VIRGO, corresponding to the inspiral and merger of two black holes, are consistent with the Einstein theory of gravity with high accuracy limited mainly by the statistical error.


In a recent paper (Konoplya & Zhidenko, 2016) the authors suggest that there is a number of alternative theories of gravity which produce the same black-hole behavior at far distances from their surfaces, but lead to qualitatively different features near the event horizon.

LIGO and Virgo data provide the angular momentum and mass of the final black hole with rather large allowance of tens of percents. The authors show that this indeterminacy in the range of the black-hole parameters allows for some not negligible deformations of the Kerr spacetime leading to the same frequencies of black-hole ringing. This means that at the current precision of the experiment there remain some possibilities for alternative theories of gravity.

Image: Simulation of a black hole merger. Credit: NASA's Goddard Space Flight Center/P. Cowperthwaite, Univ. of Maryland

Thus, they claim that there might exist a strongly deformed Kerr-like black hole, corresponding to an alternative theory of gravity, such that its behavior in the post-Newtonian regime is quite similar to Kerr black hole, while its near-horizon behavior is different.

The authors conclude that in order to disprove the above proposal, one needs to determine black-hole parameters with high accuracy. In the future this could be done either by improving the accuracy of detection of the gravitational-wave profile or with complementary observations of black holes in the electromagnetic spectrum, which could potentially give us an image of a black hole.

  • Konoplya & Zhidenko 2016 - Detection of gravitational waves from black holes: Is there a window for alternative theories? (arXiv)
  • Simulation of a black hole merger - (NASA)



Etichette:

Comments

Post a Comment

Popular posts from this blog

Astrophysics collection (March 11, 2016)

Latest astrophysics news Rotation curves of galaxies as a test of MOND? Galaxies are rotating with such speed that the gravity generated by their observable matter could not possibly hold them together. In a recent paper ( Haghi et al. 2016 ) the authors test the Modified Newtonian Dynamics (MOND).    Read>> A binary origin for a central compact object (CCO)? Doroshenko et al. 2016 investigate the possible binary origin of the CCO XMMUJ173203.3-344518 .   Read>> Rapidly rotating pulsars as possible sources of fast radio bursts (FRB) In a recent paper ( Lyutikov et al. 2016 ) the authors discuss possible association of fast radio bursts (FRBs) with supergiant pulses emitted by young pulsars.   Read>> Supernovae from WD-WD direct collisions In recent years it was suggested that WD-WD direct collisions (probably extremely rare and occurring only in dense stellar clusters) provide an additional channel for supernova...
Post a Comment
Read more

ORBITAL PERIODS OF THE PLANETS

For orbital period generally we refer to the sidereal period, that is the temporal cycle that it takes an object to make a full orbit, relative to the stars. This is the orbital period in an inertial (non-rotating) frame of reference (365,25 days for the earth).
Post a Comment
Read more

A BINARY ORIGIN FOR A CENTRAL COMPACT OBJECT (CCO)?

Figure: False-Colour X-ray and infrared emission image from the core of the infrared shell. The RGB colours correspond to Chandra X-ray 0.2-10 keV (blue), IRAC infrared 8 μm (green), and HPACS 70 μm (red) data. The intensity scale is logarithmic for all channels. Overlaid are equal brightness levels from the MIPS 24 μm band. Note that around the CCO the infrared emission is suppressed in the 70 μm band and enhanced in the 24 μm band suggesting higher dust temperature. Credit: Doroshenko et al 2016 Central compact objects (CCOs) are thought to be young isolated neutron stars that were born during the preceding core-collapse supernova explosion.
Post a Comment
Read more