scholarly journals A Study of the Long‐Term Evolution of Quasi‐Periodic Oscillations in the Accretion‐Powered X‐Ray Pulsar 4U 1626−67

2008 ◽  
Vol 676 (2) ◽  
pp. 1184-1188 ◽  
Author(s):  
Ramanpreet Kaur ◽  
Biswajit Paul ◽  
Brijesh Kumar ◽  
Ram Sagar
Keyword(s):  
Long Term Evolution ◽  
Periodic Oscillations ◽  
X Ray ◽  
Term Evolution

scholarly journals The long-term evolution of the accreting millisecond X-ray pulsar Swift J1756.9−2508

2010 ◽  
Vol 403 (3) ◽  
pp. 1426-1432 ◽  
Author(s):  
Alessandro Patruno ◽  
Diego Altamirano ◽  
Chris Messenger
Keyword(s):  
Long Term Evolution ◽  
X Ray ◽  
Term Evolution

scholarly journals On the long-term evolution of rotating radio transients

2020 ◽  
Vol 500 (3) ◽  
pp. 3281-3289
Author(s):  
A A Gençali ◽  
Ü Ertan
Keyword(s):  
Long Term Evolution ◽  
Compact Objects ◽  
Dipole Field ◽  
Death Valley ◽  
X Ray ◽  
Term Evolution ◽  
Radio Transients ◽  
Rotating Radio Transients ◽  
Field Strengths

ABSTRACT Investigation of the long-term evolution of rotating radio transients (RRATs) is important to understand the evolutionary connections between the isolated neutron star populations in a single picture. The X-ray luminosities of RRATs (except one source) are not known. In the fallback disc model, we have developed a method to estimate the dipole field strengths of RRATs without X-ray information. We have found that RRATs could have dipole field strengths, B0, at the poles ranging from ∼7 × 109 to ∼6 × 1011 G which fill the gap between the B0 ranges of central compact objects (CCOs) and dim isolated neutron stars (XDINs) estimated in the same model. In our model, most of RRATs are evolving at ages (∼2–6) × 105 yr, much smaller than their characteristic ages, such that, cooling luminosities of a large fraction of relatively nearby RRATs could be detected by the eROSITA all-sky survey. Many RRATs are located above the upper border of the pulsar death valley with the fields inferred from the dipole-torque formula, while they do not show strong, continuous radio pulses. The B0 values estimated in our model, place all RRATs either into the death valley or below the death line. We have tentatively proposed that RRATs could be the sources below their individual death points, and their short radio bursts could be ignited by the disc-field interaction occasionally enhancing the flux of open field lines through the magnetic poles. We have also discussed the evolutionary links between CCOs, RRATs, and XDINs.

scholarly journals X-RAY ENHANCEMENT AND LONG-TERM EVOLUTION OF SWIFT J1822.3–1606

2013 ◽  
Vol 778 (2) ◽  
pp. 119 ◽  
Author(s):  
Onur Benli ◽  
Ş. Çalışkan ◽  
Ü. Ertan ◽  
M. A. Alpar ◽  
J. E. Trümper ◽  
...  
Keyword(s):  
Long Term Evolution ◽  
X Ray ◽  
Term Evolution

scholarly journals Accreting, highly magnetized neutron stars at the Eddington limit: a study of the 2016 outburst of SMC X-3

2018 ◽  
Vol 614 ◽  
pp. A23 ◽  
Author(s):  
Filippos Koliopanos ◽  
Georgios Vasilopoulos
Keyword(s):  
Neutron Stars ◽  
Long Term Evolution ◽  
Emission Lines ◽  
Pulse Profile ◽  
Emission Pattern ◽  
X Ray ◽  
Term Evolution ◽  
Short And Long Term ◽  
Eddington Limit

Aims. We study the temporal and spectral characteristics of SMC X-3 during its recent (2016) outburst to probe accretion onto highly magnetized neutron stars (NSs) at the Eddington limit. Methods. We obtained XMM-Newton observations of SMC X-3 and combined them with long-term observations by Swift. We performed a detailed analysis of the temporal and spectral behavior of the source, as well as its short- and long-term evolution. We have also constructed a simple toy-model (based on robust theoretical predictions) in order to gain insight into the complex emission pattern of SMC X-3. Results. We confirm the pulse period of the system that has been derived by previous works and note that the pulse has a complex three-peak shape. We find that the pulsed emission is dominated by hard photons, while at energies below ~1 keV, the emission does not pulsate. We furthermore find that the shape of the pulse profile and the short- and long-term evolution of the source light-curve can be explained by invoking a combination of a “fan” and a “polar” beam. The results of our temporal study are supported by our spectroscopic analysis, which reveals a two-component emission, comprised of a hard power law and a soft thermal component. We find that the latter produces the bulk of the non-pulsating emission and is most likely the result of reprocessing the primary hard emission by optically thick material that partly obscures the central source. We also detect strong emission lines from highly ionized metals. The strength of the emission lines strongly depends on the phase. Conclusions. Our findings are in agreement with previous works. The energy and temporal evolution as well as the shape of the pulse profile and the long-term spectra evolution of the source are consistent with the expected emission pattern of the accretion column in the super-critical regime, while the large reprocessing region is consistent with the analysis of previously studied X-ray pulsars observed at high accretion rates. This reprocessing region is consistent with recently proposed theoretical and observational works that suggested that highly magnetized NSs occupy a considerable fraction of ultraluminous X-ray sources.

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