Discovery of hard X-ray pulsations from the transient source GRO J1744 – 28

Finger, Mark H.; Koh, Danny T.; Nelson, R.D.; Prince, Thomas A.; Vaughan, Brian; Wilson, Robert B.

doi:10.1038/381291a0

Cited by 103 publications

(100 citation statements)

References 16 publications

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“…We start making some preliminary considerations on the size of its accretion disk. Assuming an NS mass of 1.69 M⊙, a companion's mass of 0.24 M⊙ (Rappaport & Joss 1997) and the binary period of 11.83 d (Finger et al 1996), we find that the pulsar Roche lobe radius is ∼ 43 lt-s, and the circularization radius ∼ 4 lt-s (Eq. 4.6 and 4.21 in Frank et al 2002), so that the outer disc radius, which should lie in between these two values, would easily accommodate the overall variation scale of the observed lags.…”

Section: Discussionmentioning

confidence: 99%

“…The pulsar (Pspin = 467 ms) orbits in a nearly circular path (eccentricity < 1.1 × 10 −3 ) with a period of 11.8337 d, and a projected semi-major axis of 2.6324 lt-s. The mass function (1.3638 × 10 −4 M⊙) indicate an evolved low-mass (M⊙ ∼ 0.2 M⊙) companion star and a nearly faceon inclination angle (Finger et al 1996).…”

Section: Introductionmentioning

confidence: 99%

“…Calculations on the long-term evolution of the system that account for the present-day orbital parameters (Rappaport & Joss 1997), measures of the neutron star (NS) spin-up rate (Finger et al 1996), and evidence for a propeller state at the end of its 1996 outburst (Cui 1997) indicated an intermediate NS dipole field of a few 10 11 G. Detection of a cyclotron resonance feature between 4 and c 2016 RAS 5 keV in the X-ray spectrum confirmed such expectations (D'Aì et al 2015;Doroshenko et al 2015) and firmly established GRO J1744-28 as a peculiar system in between the class of the highly magnetized (B 10 12 G), young, X-ray pulsars and the class of old NSs with low-mass companions, i.e. accreting millisecond X-ray pulsars (AMXPs) and notpulsating accreting NSs, owing to a presumed low magnetic dipole field (B 10 9 G).…”

Section: Introductionmentioning

confidence: 99%

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Discovery of hard phase lags in the pulsed emission of GRO J1744−28

D’Aí¹,

Burderi

Salvo

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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We report on the discovery and energy dependence of hard phase lags in the 2.14 Hz pulsed profiles of GRO J1744-28. We used data from XMM-Newton and NuSTAR. We were able to well constrain the lag spectrum with respect to the softest (0.3-2.3 keV) band: the delay shows increasing lag values reaching a maximum delay of ∼ 12 ms, between 6 and 6.4 keV. After this maximum, the value of the hard lag drops to ∼ 7 ms, followed by a recovery to a plateau at ∼ 9 ms for energies above 8 keV. N uST AR data confirm this trend up to 30 keV, but the measurements are statistically poorer, and therefore, less constraining. The lag-energy pattern up to the discontinuity is well described by a logarithmic function. Assuming this is due to a Compton reverberation mechanism, we derive a size for the Compton cloud R cc ∼ 120 R g , consistent with previous estimates on the magnetospheric radius. In this scenario, the sharp discontinuity at ∼ 6.5 keV appears difficult to interpret and suggests the possible influence of the reflected component in this energy range. We therefore propose the possible coexistence of both Compton and disc reverberation to explain the scale of the lags and its energy dependence.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Discovery of hard phase lags in the pulsed emission of GRO J1744−28

D’Aí¹,

Burderi

Salvo

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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“…GRO J1744-28 was discovered with BATSE on 1995 December 2, when over 80 hard X-ray bursts with durations of 10-30 s were detected [2]. The pulsar period is 467 ms, and pulsations are detected in the persistent emission and in the type II bursts (see [3], [4]). The pulsar is in a nearly circular orbit (e < 1.1 x 10~3) with an 11.8 day orbital period [3].…”

mentioning

confidence: 99%

“…The pulsar period is 467 ms, and pulsations are detected in the persistent emission and in the type II bursts (see [3], [4]). The pulsar is in a nearly circular orbit (e < 1.1 x 10~3) with an 11.8 day orbital period [3]. The very small X-ray mass function indicates that the companion is most likely a low-mass (M < 1M 0 ) star.…”

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confidence: 99%

X-Ray Burst Sources

Lewin

1998

Highlights astron.

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For detailed reviews on X-ray burst sources, covering most information that was available prior to 1994, see [1].Since those reviews there have been very important new developments. First, a surprisingly new animal, GRO J1744-28 (better known as the Bursting Pulsar), made its debut in 1995. Second, but NOT last, in 1996/97 kHz pulsations were discovered in the persistent emission of several burst sources, and near coherent pulsations were detected in type I X-ray bursts.The Bursting Pulsar. GRO J1744-28 was discovered with BATSE on 1995 December 2, when over 80 hard X-ray bursts with durations of 10-30 s were detected [2]. The pulsar period is 467 ms, and pulsations are detected in the persistent emission and in the type II bursts (see [3], [4]). The pulsar is in a nearly circular orbit (e < 1.1 x 10~3) with an 11.8 day orbital period [3]. The very small X-ray mass function indicates that the companion is most likely a low-mass (M < 1M 0 ) star. GRO J1744-28 joins just 7 other pulsars detected in low-mass X-ray binary (LMXB) systems.The first major outburst of the source lasted from its discovery on 1995 December 2 until 1995 May. A less intense reactivation was observed during 1995 June-July. The beginning of a second major outburst was detected with BATSE on 1996 December 2, exactly one year after the first detection of the source [5]. The second large outburst is nearly a carbon-copy of the first. The long-term light curves show similar profiles. In both outbursts the rate of repetitive X-ray bursts was 150-200 per day (corrected for Earth occultation and live time) on the first day of activity; thereafter the rate settled down to 30-50 per day for the duration of the outburst [6].Observations with OSSE on CGRO showed that the phase of the 467 ms pulsations during and after bursts lags the phase prior to bursts by as much as 90 ms [7]. Observations with RXTE confirmed the pulse phase lags after bursts [8] and showed that the persistent emission following bursts is often depressed below its pre-burst level [9]. The RXTE PCA spectrum of the source is typical of X-ray pulsars [9]. The brightest bursts observed with RXTE in 1996 January had peak intensities of ~75 Crab (although this number is somewhat uncertain due to large dead time corrections). At an assumed distance of 7 kpc this corresponds to an assumed isotropic burst peak luminosity in excess of 50 Eddington luminosities! Kouveliotou et al. suggested that the repetitive bursts are caused by an instability in the accretion flow onto the neutron star [2]. A thermonuclear flash (type I X-ray burst) model for the repetitive bursts is excluded because the persistent X-ray emission during 1995 December 2 and 1996 December 2 was insufficient to account for the required replenishment of burnt fuel through accretion. The upper limits for the ratio, a, of the 20-100 keV persistent emission to the timeaveraged burst emission are a < 4 (3

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Testing the Equation of State with Electromagnetic Observations

Degenaar

Suleimanov

2018

Astrophysics and Space Science Library

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Neutron stars are the densest, directly observable stellar objects in the universe and serve as unique astrophysical laboratories to study the behavior of matter under extreme physical conditions. This book chapter is devoted to describing how electromagnetic observations, particularly at X-ray, optical and radio wavelengths, can be used to measure the mass and radius of neutron stars and how this leads to constraints on the equation of state of ultra-dense matter. Having accurate theoretical models to describe the astrophysical data is essential in this effort. We will review different methods to constrain neutron star masses and radii, discuss the main observational results and theoretical developments achieved over the past decade, and provide an outlook of how further progress can be made with new and upcoming ground-based and space-based observatories.

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Discovery of hard X-ray pulsations from the transient source GRO J1744 – 28

Cited by 103 publications

References 16 publications

Discovery of hard phase lags in the pulsed emission of GRO J1744−28

Discovery of hard phase lags in the pulsed emission of GRO J1744−28

X-Ray Burst Sources

Testing the Equation of State with Electromagnetic Observations

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