Analysis investigates a high-frequency bump within the X-ray binary GX 339-4

A global workforce of astronomers has inspected a low-mass X-ray binary system generally known as GX 339-4. Outcomes of the research, reported in a paper printed Nov. 21 on the pre-print server arXiv, shed extra mild on the high-frequency bump noticed within the energy density spectrum of GX 339−4 and supply extra insights into the properties of this method.

X-ray binaries (XRBs) are techniques composed of a traditional star or a white dwarf transferring mass onto a compact object, which can be both a neutron star or a black gap. XRBs are additional divided into low-mass X-ray binaries (LMXBs) and high-mass X-ray binaries (HMXBs), relying on the mass of the accompanying star.

At a distance of about 39,000 mild years away from the Earth, GX 339-4 is a recurrent black gap LMXB first detected in 1973. Its black gap is estimated to be no less than 5.8 instances as huge because the solar. GX 339−4 has undergone frequent outbursts, skilled quasi-periodic oscillations (QPOs) and displayed all of the black gap accretion states over the last 30 years.

All in all, GX 339-4 has been comprehensively investigated in any respect wavelengths, which makes it probably the most studied black gap LMXBs. Earlier observations of this method have discovered a high-frequency bump in its energy density spectrum (PDS) that ought to originate within the X-ray corona. This bump is characterised by a frequency exceeding 30 Hz and has a root imply sq. (rms) of round 2–3%.

A gaggle of astronomers led by Yuexin Zhang of the College of Groningen, The Netherlands, determined to research archival knowledge from the Rossi X-ray Timing Explorer (RXTE), spanning from 1996 to 2012, to discover the character of this high-frequency bump.

In consequence, the workforce detected the bump in 39 RXTE observations of GX 339-4, all of which additionally present type-C QPOs within the low-hard state and the hard-intermediate state. They discovered that the rms of the bump is dependent upon the frequency of the type-C QPO and the hardness ratio (HR).

“When the HR is between ∼0.8 and 1.3 and the QPO frequency is between ∼0.1 Hz and a couple of Hz, the rms amplitude of the bump is ∼4–9%, whereas when the HR decreases beneath 0.8 all the way down to 0.2 and the QPO frequency will increase from ∼2 Hz as much as 8 Hz the bump is just not detected with higher limits of the rms amplitude between 3 and 10%,” the researchers defined.

Typically, the astronomers discovered that the radio flux of GX 339−4 is kind of low when in comparison with comparable X-ray binaries, however the rms amplitude of the bump is excessive and the X-ray corona is sizzling. This means that in GX 339−4, extra vitality within the system within the low-hard and hard-intermediate states is directed in direction of the X-ray corona than within the case of different investigated black gap LMXBs.

Based on the authors of the paper, the presence of the bump in GX 339−4 means that within the onerous state of this supply, many of the accretion vitality is directed to the corona as an alternative of getting used to eject the radio jet.

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