BROADBAND X-RAY SPECTRA OF THE ULTRALUMINOUS X-RAY SOURCE HOLMBERG IX X-1 OBSERVED WITHNuSTAR,XMM-NEWTON,ANDSUZAKU

Walton, D. J.; Harrison, Fiona A.; Grefenstette, Brian W.; Miller, J. M.; Bachetti, Matteo; Barret, D.; Boggs, Steven E.; Christensen, Finn Erland; Craig, William W.; Fabian, A. C.; Fuerst, F.; Hailey, Charles J.; Madsen, K. K.; Parker, M. L.; Ptak, Andrew; Rana, V.; Stern, Daniel; Webb, N.; Zhang, W. W.

doi:10.1088/0004-637x/793/1/21

Cited by 127 publications

(193 citation statements)

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“…This hard-energy turn over around 6-10 keV is also seen for bright individual ULXs studied by XMM-Newton and NuSTAR (Stobbart et al 2006;Gladstone et al 2009;Walton et al 2013Walton et al , 2014Bachetti et al 2013;Rana et al 2015) and is interpreted as super-Eddington accretion onto a stellar-mass black hole instead of an intermediate-mass black hole in a low/hard accretion state (e.g., Shakura & Sunyaev 1973;King et al 2001;Poutanen et al 2007;Gladstone et al 2009;Sutton et al 2013).…”

Section: Introductionmentioning

confidence: 64%

“…In addition to the Galactic BH binaries, accreting pulsars, and "Z-sources," several ULXs observed by NuSTAR (Bachetti et al 2013;Walton et al 2013Walton et al , 2014Rana et al 2015) are included as gray upside-down triangles. We note that the ULXs are well-separated from the Galactic binary tracks in the colorintensity plot (Figure 10), as expected given their high luminosities.…”

Section: Nustar Color Diagnostics For Compact Binariesmentioning

confidence: 99%

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A HARD X-RAY STUDY OF THE NORMAL STAR-FORMING GALAXY M83 WITH NuSTAR

Yukita

Hornschemeier

Lehmer

et al. 2016

ApJ

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We present the results from sensitive, multi-epoch NuSTAR observations of the late-type star-forming galaxy M83 (d = 4.6 Mpc). This is the first investigation to spatially resolve the hard (E 10 > keV) X-ray emission of this galaxy. The nuclear region and ∼20 off-nuclear point sources, including a previously discovered ultraluminous X-ray source, are detected in our NuSTAR observations. The X-ray hardnesses and luminosities of the majority of the point sources are consistent with hard X-ray sources resolved in the starburst galaxy NGC 253. We infer that the hard X-ray emission is most likely dominated by intermediate accretion state black hole binaries and neutron star low-mass X-ray binaries (Z-sources). We construct the X-ray binary luminosity function (XLF) in the NuSTAR band for an extragalactic environment for the first time. The M83 XLF has a steeper XLF than the X-ray binary XLF in NGC 253, which is consistent with previous measurements by Chandra at softer X-ray energies. The NuSTAR integrated galaxy spectrum of M83 drops quickly above 10 keV, which is also seen in the starburst galaxies NGC 253, NGC 3310, and NGC 3256. The NuSTAR observations constrain any active galactic nucleus (AGN) to be either highly obscured or to have an extremely low luminosity of 10 38 erg s −1 (10-30 keV), implying that it is emitting at a very low Eddington ratio. An X-ray point source that is consistent with the location of the nuclear star cluster with an X-ray luminosity of a few times 10 38 erg s −1 may be a low-luminosity AGN but is more consistent with being an X-ray binary.

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Section: Introductionmentioning

confidence: 64%

Section: Nustar Color Diagnostics For Compact Binariesmentioning

confidence: 99%

A HARD X-RAY STUDY OF THE NORMAL STAR-FORMING GALAXY M83 WITH NuSTAR

Yukita

Hornschemeier

Lehmer

et al. 2016

ApJ

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“…Its hard X-ray spectrum below 10 keV had previously led to speculation that it might host an intermediate-mass black hole accreting in the low/hard state, similar to what is seen in Galactic black hole binaries at low luminosities (Sutton et al 2012; see Remillard & McClintock 2006 for a review of accretion states in Galactic binaries). Our recent coordinated observations with the NuSTAR and XMM-Newton observatories have subsequently revealed a broadband X-ray spectrum inconsistent with this identification (Walton et al 2015a), similar to the other ULX systems observed by NuSTAR to date (Bachetti et al 2013;Walton et al 2014Walton et al , 2015bMukherjee et al 2015;Rana et al 2015). Instead, the broadband spectrum implies instead that NGC 5907 ULX1 is likely a system accreting at high-or even super-Eddington rates, as suggested by Sutton et al (2013a).…”

Section: Introductionmentioning

confidence: 64%

A 78 Day X-Ray Period Detected From NGC 5907 Ulx1 by Swift

Walton

Fürst

Bachetti

et al. 2016

ApJL

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We report the detection of a 78.1 ± 0.5 day period in the X-ray light curve of the extreme ultraluminous X-ray source NGC 5907 ULX1 ( L X,peak ∼ 5 × 10 40 erg s−1), discovered during an extensive monitoring program with Swift. These periodic variations are strong, with the observed flux changing by a factor of ∼3–4 between the peaks and the troughs of the cycle; our simulations suggest that the observed periodicity is detected comfortably in excess of 3σ significance. We discuss possible origins for this X-ray period, but conclude that at the current time we cannot robustly distinguish between orbital and super-orbital variations.

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“…85 (see Marinucci et al 2012 for details on data reduction). The spectral cross-calibration between NuSTAR and Suzaku XIS is fairly good, with fluxes consistent within ∼10% (Walton et al 2014;Brenneman et al 2014).…”

Section: Suzakumentioning

confidence: 71%