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Hill, Martin; Cilliers, C. J.

doi:10.1023/a:1003869230591

Cited by 40 publications

(45 citation statements)

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“…In fact, only upper limits on the 5-GHz radio luminosity of a few neutron star LMXBs have been reported in the literature at X-ray luminosities 10 34 erg s -1 (e.g., Tudor et al 2017;Gallo et al 2018). By contrast, while in their disk states, two of the three tMSPs have been firmly detected at 5-GHz with X-ray luminosities between 10 32 -10 34 erg s -1 (Hill et al 2011;Deller et al 2015) (the third tMSP is at much higher L X , Papitto et al 2013). Despite the limited statistics, tMSPs appear to be more radio bright than typical neutron star LMXBs at the same X-ray luminosity, possibly due to the ejection of disk matter by a propeller mechanism (Deller et al 2015), though the existing radio upper limits for such systems at L X ∼ 10 32 -10 34 erg s -1 are not particularly constraining.…”

Section: Radio Continuum Observationsmentioning

confidence: 86%

“…In all the known tMSPs that have been observed in their disk states, bright, flat-spectrum radio emission is present. This has been explained by partially self-absorbed synchrotron radiation coming from a compact jet-like outflow (e.g., Hill et al 2011;Deller et al 2015;Papitto & Torres 2015), though the short timescale anti-correlation between X-ray and radio emission in the tMSP J1023+0038 in its disk state clouds a simple jet interpretation for the radio emission (Bogdanov et al 2018).…”

Section: Radio Continuum Observationsmentioning

confidence: 99%

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A Multiwavelength View of the Neutron Star Binary 1FGL J1417.7–4402: A Progenitor to Canonical Millisecond Pulsars

Swihart

Strader

Shishkovsky

et al. 2018

ApJ

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The Fermi γ-ray source 1FGL J1417.7-4407 (J1417) is a compact X-ray binary with a neutron star primary and a red giant companion in a ∼5.4 day orbit. This initial conclusion, based on optical and X-ray data, was confirmed when a 2.66 ms radio pulsar was found at the same location (and with the same orbital properties) as the optical/X-ray source. However, these initial studies found conflicting evidence about the accretion state and other properties of the binary. We present new optical, radio, and X-ray observations of J1417 that allow us to better understand this unusual system. We show that one of the main pieces of evidence previously put forward for an accretion disk-the complex morphology of the persistent Hα emission line-can be better explained by the presence of a strong, magnetically driven stellar wind from the secondary and its interaction with the pulsar wind. The radio spectral index derived from VLA/ATCA observations is broadly consistent with that expected from a millisecond pulsar, further disfavoring an accretion disk scenario. X-ray observations show evidence for a double-peaked orbital light curve, similar to that observed in some redback millisecond pulsar binaries and likely due to an intrabinary shock. Refined optical light curve fitting gives a distance of 3.1±0.6 kpc, confirmed by a Gaia DR2 parallax measurement. At this distance the X-ray luminosity of J1417 is (1.0 +0.4 −0.3 ) ×10 33 erg s −1 , which is more luminous than all known redback systems in the rotational-powered pulsar state, perhaps due to the wind from the giant companion. The unusual phenomenology of this system and its differing evolutionary path from redback millisecond pulsar binaries points to a new eclipsing pulsar "spider" subclass that is a possible progenitor of normal field millisecond pulsar binaries.

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Section: Radio Continuum Observationsmentioning

confidence: 86%

Section: Radio Continuum Observationsmentioning

confidence: 99%

A Multiwavelength View of the Neutron Star Binary 1FGL J1417.7–4402: A Progenitor to Canonical Millisecond Pulsars

Swihart

Strader

Shishkovsky

et al. 2018

ApJ

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“…The magenta stars are accreting millisecond X-ray pulsars (AMXPs: Migliari et al 2005Migliari et al , 2011Tudor et al 2016Tudor et al , 2017Tetarenko et al 2017;van den Eijnden et al 2018a;Strohmayer et al 2018a). The green triangles are transitional millisecond pulsars (tMSPs) when they have switched from rotation powered to accretion powered mode (Hill et al 2011;Papitto et al 2013;Deller et al 2015;Bogdanov et al 2018). The purple upside-down triangles are Z sources (Migliari & Fender 2006).…”

Section: Discussionmentioning

confidence: 99%

“…Presently, tM-SPs are among the most radio-bright NS systems and, if they obey their current observed L r -L x trend (Deller et al 2015), are expected to be at least an order of magnitude brighter in the radio than our upper limit for 4U 1543−624. Furthermore, they exhibit many other unique phenomena, e.g., optical pulsations, radio pulsations, rapid X-ray and radio flaring, gamma ray emission -none of which have been observed in 4U 1543−624 (Hill et al 2011;Papitto et al 2013;Bogdanov & Halpern 2015;Bogdanov et al 2015;Zampieri et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Observations of the Ultra-compact X-Ray Binary 4U 1543-624 in Outburst with NICER, INTEGRAL, Swift, and ATCA

Ludlam

Shishkovsky

Bult

et al. 2019

ApJ

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We report on X-ray and radio observations of the ultra-compact X-ray binary 4U 1543−624 taken in August 2017 during an enhanced accretion episode. We obtained NICER monitoring of the source over a ∼ 10 day period during which target-of-opportunity observations were also conducted with Swift, INTEGRAL, and ATCA. Emission lines were measured in the NICER X-ray spectrum at ∼ 0.64 keV and ∼ 6.4 keV that correspond to O and Fe, respectively. By modeling these line components, we are able to track changes in the accretion disk throughout this period. The innermost accretion flow appears to move inwards from hundreds of gravitational radii (R g = GM/c 2 ) at the beginning of the outburst to < 8.7 R g at peak intensity. We do not detect the source in radio, but are able to place a 3σ upper limit on the flux density at 27 µJy beam −1 . Comparing the radio and X-ray luminosities, we find that the source lies significantly away from the range typical of black holes in the L r -L x plane, suggesting a neutron star (NS) primary. This adds to the evidence that NSs do not follow a single track in the L r -L x plane, limiting its use in distinguishing between different classes of NSs based on radio and X-ray observations alone.

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“…A first batch of S. rufinosus was therefore released in 1997 (Hill, 1998b). Having then been introduced in 46 sites they established in at least 31 and completely controlled A. filiculoides in 20 (Hill and Cilliers, 1999;Hill 1999). Since the predator certainly ignores countries borders, reconciling the opposing views of promoters of Azolla development for agronomic purposes and promoters of its destruction is really difficult.…”

Section: Azolla As a Weedmentioning

confidence: 99%