INITIAL RESULTS FROM<i>NuSTAR</i>OBSERVATIONS OF THE NORMA ARM

Bodaghee, A.; Tomsick, John A.; Krivonos, R.; Stern, Daniel; Bauer, F. E.; Fornasini, Francesca M.; Barrière, Nicolas M.; Boggs, Steven E.; Christensen, Finn Erland; Craig, William W.; Gotthelf, E. V.; Hailey, Charles J.; Harrison, Fiona A.; Hong, Jaesub; Mori, Kaya; Zhang, William W.

doi:10.1088/0004-637x/791/1/68

Cited by 8 publications

(6 citation statements)

References 34 publications

(43 reference statements)

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“…Nevertheless, the Arches cluster core and cloud are not strongly contaminated and can be well localized in FPMA images as obviously seen in Fig. 2, and also based on actual ghost-rays seen in other NuSTAR observations (Bodaghee et al 2014).…”

Section: Nustarsupporting

confidence: 71%

NuSTAR and XMM–Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud

Krivonos

Clavel

Hong

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present results of long NuSTAR (200 ks) and XMM-Newton (100 ks) observations of the Arches stellar cluster, a source of bright thermal (kT ∼2 keV) X-rays with prominent Fe XXV Kα 6.7 keV line emission and a nearby molecular cloud, characterized by an extended non-thermal hard X-ray continuum and fluorescent Fe Kα 6.4 keV line of a neutral or low ionization state material around the cluster. Our analysis demonstrates that the non-thermal emission of the Arches cloud underwent a dramatic change, with its homogeneous morphology, traced by fluorescent Fe Kα line emission, vanishing after 2012, revealing three bright clumps. The declining trend of the cloud emission, if linearly fitted, is consistent with half-life decay time of ∼ 8 years. Such strong variations have been observed in several other molecular clouds in the Galactic Centre, including the giant molecular cloud Sgr B2, and point toward a similar propagation of illuminating fronts, presumably induced by the past flaring activity of Sgr A .

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Section: Nustarsupporting

confidence: 71%

NuSTAR and XMM–Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud

Krivonos

Clavel

Hong

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…Ghost-ray photons from a bright persistent source or X-ray transient can be significant, with a visible pattern in the NuSTAR image. Although some observations of the GC and Norma field have been severely affected by ghost-ray background (Bodaghee et al 2014), it is not important in the NuSTAR mini-survey and Sgr A* observations.…”

Section: Discussionmentioning

confidence: 99%

NuSTARHARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

Mori

Hailey

Krivonos

et al. 2015

ApJ

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We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuS-TAR. NuSTAR resolves the hard X-ray source IGR J17456−2901 into non-thermal X-ray filaments, molecular clouds, point sources and a previously unknown central component of hard X-ray emission (CHXE). NuSTAR detects four non-thermal X-ray filaments, extending the detection of their powerlaw spectra with Γ ∼ 1.3-2.3 up to ∼ 50 keV. A morphological and spectral study of the filaments suggests that their origin may be heterogeneous, where previous studies suggested a common origin in young pulsar wind nebulae (PWNe). NuSTAR detects non-thermal X-ray continuum emission spatially correlated with the 6.4 keV Fe Kα fluorescence line emission associated with two Sgr A molecular clouds: MC1 and the Bridge. Broad-band X-ray spectral analysis with a Monte-Carlo based X-ray reflection model self-consistently determined their intrinsic column density (∼ 10 23 cm −2 ), primary X-ray spectra (power-laws with Γ ∼ 2) and set a lower limit of the X-ray luminosity of Sgr A* flare illuminating the Sgr A clouds to L X 10 38 erg s −1 . Above ∼ 20 keV, hard X-ray emission in the central 10 pc region around Sgr A* consists of the candidate PWN G359.95−0.04 and the CHXE, possibly resulting from an unresolved population of massive CVs with white dwarf masses M W D ∼ 0.9M . Spectral energy distribution analysis suggests that G359.95−0.04 is likely the hard X-ray counterpart of the ultra-high gamma-ray source HESS J1745−290, strongly favoring a leptonic origin of the GC TeV emission.

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“…Therefore, initially (at the observation planning stage), we checked for possible contamination of GR photons from this source to the useful signal. According to NuSTAR's experience with GRs from the very bright system 4U 1630-47 (Bodaghee et al 2014), the direct GRs are observed within a ∼ 20 ′ radius circle, which made observations of IGR J18027-2016 possible. Indeed, Fig.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

NuSTARobservations of the supergiant X-ray pulsar IGR J18027−2016: accretion from the stellar wind and possible cyclotron absorption line

Lutovinov

Tsygankov

Постнов

et al. 2016

Mon. Not. R. Astron. Soc.

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We report on the first focused hard X-ray view of the absorbed supergiant system IGR J18027-2016 performed with the NuSTAR observatory. The pulsations are clearly detected with a period of P spin = 139.866(1) s and a pulse fraction of about 50-60% at energies from 3 to 80 keV. The source demonstrates an approximately constant X-ray luminosity on a time scale of more than dozen years with an average spin-down rate oḟ P ≃ 6×10 −10 s s −1 . This behaviour of the pulsar can be explained in terms of the wind accretion model in the settling regime. The detailed spectral analysis at energies above 10 keV was performed for the first time and revealed a possible cyclotron absorption feature at energy ∼ 23 keV. This energy corresponds to the magnetic field B ≃ 3×10 12G at the surface of the neutron star, which is typical for X-ray pulsars.

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INITIAL RESULTS FROMNuSTAROBSERVATIONS OF THE NORMA ARM

Cited by 8 publications

References 34 publications

NuSTAR and XMM–Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud

NuSTAR and XMM–Newton observations of the Arches cluster in 2015: fading hard X-ray emission from the molecular cloud

NuSTARHARD X-RAY SURVEY OF THE GALACTIC CENTER REGION. I. HARD X-RAY MORPHOLOGY AND SPECTROSCOPY OF THE DIFFUSE EMISSION

NuSTARobservations of the supergiant X-ray pulsar IGR J18027−2016: accretion from the stellar wind and possible cyclotron absorption line

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