[Paper Review] The 2005 - 2010 multiwavelength campaign of OJ287

M. J. Valtonen, Aimo Sillanpää|arXiv (Cornell University)|Nov 15, 2011

Astrophysics and Cosmic Phenomena2 references3 citations

TL;DR

This paper presents the results of a multiwavelength campaign (2005–2010) on the quasar OJ287, confirming its binary black hole nature through precise outburst timing and spectral characteristics. The observed optical outbursts in October 2005 and September 2007 matched predictions based on general relativistic precession, with bremsstrahlung radiation and unpolarized emission, validating the model at second Post-Newtonian order and confirming the no-hair theorem via a test parameter q ≈ 1.

ABSTRACT

The light curve of quasar OJ287 extends from 1891 up today without major gaps. This is partly due to extensive studies of historical plate archives by Rene Hudec and associates, and partly due to several observing campaigns in recent times. Here we summarize the results of the 2005 - 2010 observing campaign, in which several hundred scientists and amateur astronomers took part. The main results are the following: (1) The 2005 October optical outburst came at the expected time, thus confirming the General Relativistic precession in the binary black hole system. At the same time, this result disproved the model of a single black hole system with accretion disk oscillations, as well as several toy models of binaries without relativistic precession. (2) The nature of the radiation of the 2005 October outburst was expected to be bremsstrahlung from hot gas at a temperature of 3 10^5 degrees K. This was confirmed by combined ground based and ultraviolet observations using the XMM-Newton X-ray telescope. (3) A secondary outburst of the same nature was expected at 2007 September 13. Within the accuracy of the observations (about 6 hours), it started at the correct time. Due to the bremsstrahlung nature of the outburst, the radiation was unpolarized, as expected. (4) Further synchrotron outbursts were expected following the two bremsstrahlung outbursts. They came as scheduled between 2007 October and 2009 December. (5) Due to the effect of the secondary on the overall direction of the jet, the parsec scale jet is expected to rotate in the sky by a large angle, which has been confirmed. The OJ287 binary black hole system is currently our best laboratory for testing theories of gravitation. Using OJ287, the correctness of General Relativity has now been demonstrated up to the second Post-Newtonian order, higher than has been possible using binary pulsars.

Motivation & Objective

• To test the binary black hole model of OJ287 against competing single black hole and non-relativistic binary models.
• To verify the prediction of general relativistic precession in the system by observing the timing of optical outbursts.
• To determine the radiation mechanism of the outbursts through multiwavelength and polarization data.
• To test the no-hair theorem and higher-order Post-Newtonian terms in general relativity using orbital dynamics.

Proposed method

• Modeling the system as a binary black hole with relativistic precession, using orbital solutions constrained by historical light curves.
• Predicting outburst times based on the 12-year orbital period and relativistic precession, with high-precision timing down to hours.
• Analyzing multiwavelength data (optical, UV, X-ray, radio) to identify radiation mechanisms via spectral and polarization characteristics.
• Using XMM-Newton X-ray observations to confirm bremsstrahlung emission at ~3×10⁵ K during the 2005 outburst.
• Applying a test parameter q in the equations of motion to assess deviations from general relativity, with q=1 in GR.
• Using resolved parsec-scale radio jet data to constrain the jet orientation and disk-wobble dynamics.

Experimental results

Research questions

• RQ1 Does the 2005 October outburst occur at the time predicted by the general relativistic precession model, or would alternative models predict a delay of one year?
• RQ2 Is the radiation from the 2005 outburst polarized or unpolarized, and does this support a bremsstrahlung or synchrotron origin?
• RQ3 Can the timing of the 2007 September outburst be predicted with sub-day accuracy, and does it match the precessing binary model?
• RQ4 Do the observed synchrotron outbursts between 2007 and 2009 follow the predicted sequence after the bremsstrahlung events?
• RQ5 What value does the test parameter q take in the orbital solution, and does it confirm general relativity at second Post-Newtonian order?

Key findings

• The 2005 October outburst occurred within one week of the predicted time, confirming general relativistic precession and ruling out non-precessing binary and single black hole models with disk oscillations.
• The 2005 outburst exhibited unpolarized radiation, consistent with bremsstrahlung emission at ~3×10⁵ K, confirmed by XMM-Newton X-ray observations.
• The 2007 September 13 outburst began within 6 hours of the predicted time, matching the precessing binary model with the same accuracy as Halley’s comet prediction.
• Subsequent synchrotron outbursts between October 2007 and December 2009 appeared as scheduled, supporting the model’s predictive power.
• The parsec-scale jet showed measurable rotation by 2009, consistent with the secondary black hole’s perturbation of the accretion disk.
• The test parameter q for the no-hair theorem peaked at q=1, excluding q=0 (no spin-orbit coupling) and q=2 (material body) at the 4σ level, confirming GR at higher than 1.5PN order.