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

Abstract

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. For example, the inferred ratio (~ 50-90) of the non-burst fluence to burst fluence is consistent with the thermonuclear origin of IGR J17480-2446 bursts, and is significantly different from this ratio (< 4) for type-II bursts. Our results suggest that the bursts and the mHz QPOs from IGR J17480-2446 are powered by the nuclear energy.

six pages, 1 table, 2 figures, accepted for publication in ApJ Letters

References in corpus (4)

• Thermonuclear (type-I) X-ray bursts observed by the Rossi X-ray Timing Explorer
• Faint X-ray Sources in the Globular Cluster Terzan 5
• The spin and orbit of the newly discovered pulsar IGR J17480-2446
• Signature of Temporary Burning Front Stalling from a Non-Photospheric Radius Expansion Double-peaked Burst

Cited by in corpus (15)

• Millihertz quasi-periodic oscillations and thermonuclear bursts from Terzan 5: A showcase of burning regimes
• A Fast X-ray Disk Wind in the Transient Pulsar IGR J17480-2446 in Terzan 5
• Accreting Millisecond X-Ray Pulsars
• Implications of burst oscillations from the slowly rotating accreting pulsar IGR 17480-2446 in the globular cluster Terzan 5
• X-ray bursts and burst oscillations from the slowly spinning X-ray pulsar IGR J17480-2446 (Terzan 5)
• Terzan 5 transient IGR J17480-2446: variation of burst and spectral properties with spectral states
• On the cooling tails of thermonuclear X-ray bursts: the IGR J17480-2446 link
• Spectral Evolution of a New X-ray Transient MAXI J0556-332 Observed by MAXI, Swift, and RXTE
• The pulse profile and spin evolution of the accreting pulsar in Terzan 5, IGR J17480-2446, during its 2010 outburst
• Indications for a slow rotator in the Rapid Burster from its thermonuclear bursting behaviour
• Thermonuclear X-ray bursts from the 401 Hertz accreting pulsar IGR J17498-2921: indication of burning in confined regions
• A model-independent comparison of the variability of accreting neutron stars and black holes
• Nuclear-powered X-ray millisecond pulsars
• Discovery of an accretion-rate independent absolute RMS amplitude of millihertz quasi-periodic oscillations in 4U 1636-53
• Broadband spectro-temporal investigation of neutron star low-mass X-ray binary GX 349+2