SGR 0418+5729—HOW DOES A YOUNG NEUTRON STAR SPIN DOWN TO A 9 s PERIOD WITH A DIPOLE FIELD LESS THAN 10
                    <sup>13</sup>
                    G?

Alpar, M. A.; Ertan, Ünal; Çalışkan, Şirin

doi:10.1088/2041-8205/732/1/l4

Cited by 39 publications

(51 citation statements)

References 34 publications

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“…With a dipole field below 10 13 G, in fact, it would be impossible to slow down the star to the observed 9.1 s period in less than ∼24 Myr, a time much longer than the estimated age of other SGRs/AXPs, unless SGR 0418+5729 had an exceptionally long period at birth. A possible solution was suggested by Alpar et al (2011) who have shown that if SGR 0418+5729 was born with a period >70 ms and a low dipolar field (B ≈ 10 12 G), the torque exerted by a fallback disk can spin down the star to the present period in 10 5 yr, ifṖ has to be below the observed upper limit. 10 The survival of multipolar field components ≈100 times stronger than the dipole over such a time span may, however, be an issue in the light of the known evolution of the dipolar field in magnetars (see Section 2.1).…”

Section: Discussionmentioning

confidence: 99%

Is SGR 0418+5729 Indeed a Waning Magnetar?

Turolla

Zane

Pons

et al. 2011

ApJ

110

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SGR 0418+5729 is a transient soft gamma-ray repeater which underwent a major outburst in 2009 June, during which the emission of short bursts was observed. Its properties appeared quite typical of other sources of the same class until long-term X-ray monitoring failed to detect any period derivative. The present upper limit onṖ implies that the surface dipole field is B p 7.5 × 10 12 G, well below those measured in other soft gamma-ray repeaters (SGRs) and in the Anomalous X-ray Pulsars (AXPs), a group of similar sources. Both SGRs and AXPs are currently believed to be powered by ultra-magnetized neutron stars (magnetars, B p ≈ 10 14 -10 15 G). SGR 0418+5729 hardly seems to fit in such a picture. We show that the magneto-rotational properties of SGR 0418+5729 can be reproduced if this is an aged magnetar, ≈1 Myr old, which experienced substantial field decay. The large initial toroidal component of the internal field required to match the observed properties of SGR 0418+5729 ensures that crustal fractures, and hence bursting activity, can still occur at the present time. The thermal spectrum observed during the outburst decay is compatible with the predictions of a resonant Compton scattering model (as in other SGRs/AXPs) if the field is low and the magnetospheric twist is moderate.

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Section: Discussionmentioning

confidence: 99%

Is SGR 0418+5729 Indeed a Waning Magnetar?

Turolla

Zane

Pons

et al. 2011

ApJ

110

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“…Soon after the discovery of pulsars it was found that their spin periods are increasing, implying a loss rate of rotational energy, E rot , sufficiently high to power not only the pulsed radio emission, but also the bright radio/optical/X-ray nebulae observed around the most energetic pulsars. The first striking example was provided by the pulsar PSR B0531+21, whoseĖ rot =4.6×10 38 erg s −1 matches the total energy output of the surrounding Crab nebula 3 . Most of the spin-down power is lost in a Poyntingdominated wind rather than in beamed photons from the pulsar.…”

Section: Rotationmentioning

confidence: 99%

Pulsars and Magnetars

Mereghetti

2013

Braz J Phys

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The high-energy sources known as anomalous X-ray pulsars (AXPs) and soft γ-ray repeaters (SGRs) are well explained as magnetars: isolated neutron stars powered by their own magnetic energy. After explaining why it is generally believed that the traditional energy sources at work in other neutron stars (accretion, rotation, residual heat) cannot power the emission of AXPs/SGRs, I review the observational properties of the twenty AXPs/SGRs currently known and describe the main features of the magnetar model. In the last part of this review I discuss the recent discovery of magnetars with low external dipole field and some of the relations between AXPs/SGRs and other classes of isolated neutron stars.

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“…(2009), Alpar et al (2011), andÇ alışkan et al (2013). Here, we briefly describe the basic long-term evolutionary phases of a neutron star evolving with a fallback disk.…”

Section: Long-term Evolution Of Swift J18223-1606mentioning

confidence: 99%

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

Benli

Çalışkan

Ertan

et al. 2013

ApJ

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We investigate the X-ray enhancement and the long-term evolution of the recently discovered, second "low-B magnetar" Swift J1822.3-1606 in the frame of the fallback disk model. During a soft gamma burst episode, the inner disk matter is pushed back to larger radii forming a density gradient at the inner disk. Subsequent relaxation of the inner disk could account for the observed Xray enhancement light curve of Swift J1822.3-1606. We obtain model fits to the X-ray data with basic disk parameters similar to those employed to explain the X-ray outburst light curves of other anomalous X-ray pulsars and soft gamma repeaters. The long period (8.4 s) of the neutron star can be reached by the effect of the disk torques in the long-term accretion phase (1 − 3 × 10 5 yr). The currently ongoing X-ray enhancement could be due to a transient accretion epoch or the source could still be in the accretion phase in quiescence. Considering these different possibilities, we determine the model curves that could represent the long-term rotational and the X-ray luminosity evolution of Swift J1822.3-1606, which constrain the strength of the magnetic dipole field to the range of 1 − 2 × 10 12 G on the surface of the neutron star.

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SGR 0418+5729—HOW DOES A YOUNG NEUTRON STAR SPIN DOWN TO A 9 s PERIOD WITH A DIPOLE FIELD LESS THAN 10 ¹³ G?

Cited by 39 publications

References 34 publications

Is SGR 0418+5729 Indeed a Waning Magnetar?

Is SGR 0418+5729 Indeed a Waning Magnetar?

Pulsars and Magnetars

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

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SGR 0418+5729—HOW DOES A YOUNG NEUTRON STAR SPIN DOWN TO A 9 s PERIOD WITH A DIPOLE FIELD LESS THAN 10 13 G?

Cited by 39 publications

References 34 publications

Is SGR 0418+5729 Indeed a Waning Magnetar?

Is SGR 0418+5729 Indeed a Waning Magnetar?

Pulsars and Magnetars

X-Ray Enhancement and Long-Term Evolution of Swift J1822.3–1606

Contact Info

Product

Resources

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SGR 0418+5729—HOW DOES A YOUNG NEUTRON STAR SPIN DOWN TO A 9 s PERIOD WITH A DIPOLE FIELD LESS THAN 10 ¹³ G?