X-ray bursts from the Terzan 5 transient IGR J17480-2446: nuclear rather than gravitational

Understand

The 2010 outburst of the transient neutron star low-mass X-ray binary IGR J17480-2446 has exhibited a series of unique X-ray bursts, as well as millihertz (mHz) quasi-periodic oscillations (QPOs) related to these bursts.

• It has been recently proposed that these are type-II bursts, powered by the gravitational energy.
• This implies that the current nuclear-burning based model of mHz QPOs is not correct, and this timing feature cannot be used as a tool to measure the neutron star parameters.
• We report the analysis of the Rossi X-ray Timing Explorer data of IGR J17480-2446 to show that the burst properties of this source are quite different from the properties of the type-II bursts observed from the rapid burster and GRO J1744-28.