A relativistically broadened O<scp>viii</scp> Lyα line in the ultracompact X-ray binary 4U 0614+091

Madej, Oliwia; Jonker, P. G.; Fabian, A. C.; Pinto, C.; Verbunt, F.; Plaa, J. de

doi:10.1111/j.1745-3933.2010.00892.x

Cited by 36 publications

(62 citation statements)

References 27 publications

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“…Neon also shows a gradient but with a large scatter probably due to contribution intrinsic to the sources (see e.g. Juett & Chakrabarty 2003;Madej et al 2010). However, the linear fits show negative gradients for all the abundances which is consistent with the fact that stellar evolution proceeds faster in the Galactic inner regions.…”

Section: Ism Abundancessupporting

confidence: 63%

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Pinto

Kaastra

Costantini

et al. 2013

A&A

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125

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Context. The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. Aims. We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). Methods. We used high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measured the column densities of O, Ne, Mg, and Fe with an empirical model and estimated the Galactic abundance gradients. Results. The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25% and 65-90% of the total amount of O i and Fe i is found in dust.The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Conclusions. Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.

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Section: Ism Abundancessupporting

confidence: 63%

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Pinto

Kaastra

Costantini

et al. 2013

A&A

Self Cite

125

127

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“…Schulz 1999;Migliari et al 2010). A recent XMMNewton RGS observation fits this feature with a single broad line (Madej et al 2010). The HETG spectra also require such a feature between 17 and 19 Å as is shown in the residuals in Figures 4 and 5.…”

Section: Broad Line Emissionmentioning

confidence: 91%

“…As done for the XMM-Newton RGS data (Madej et al 2010), we fit this line feature with a gravitationally broadened line model laor (Laor 1991) available in Xspec. The fits are summarized in Table 3.…”

Section: Broad Line Emissionmentioning

confidence: 99%

Dynamical K Edge and Line Variations in the X-Ray Spectrum of the Ultra-Compact Binary 4u 0614+091

Schulz

Nowak

Chakrabarty

et al. 2010

ApJ

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We observed the ultra-compact binary candidate 4U 0614+091 for a total of 200 ks with the high-energy transmission gratings on board the Chandra X-ray Observatory. The source is found at various intensity levels with spectral variations present. X-ray luminosities vary between 2.0 × 10 36 erg s −1 and 3.5 × 10 36 erg s −1 . Continuum variations are present at all times and spectra can be fit well with a power-law component, a high kT blackbody component, and a broad line component near oxygen. The spectra require adjustments to the Ne K edge and in some occasions also to the Mg K edge. Once further resolved, the Ne K edge region appears variable in terms of optical depths and morphology. The edge vicinity reveals an average velocity smear of ∼3500 km s −1 implying a characteristic radius of the order of <10 9 cm consistent with an ultra-compact binary nature. The variability proves that the excess is intrinsic to the source. The data seem to indicate excess column densities of up to several 10 18 cm −2 . However, there are some serious problems with an Ne i interpretation in ultra-compact disks and we need to consider alternative interpretations, which include a variable O viii ionization edge, as likely candidates. We test such possibilities with existing observations. The prominent soft emission line complex near the O viii Ly α position appears extremely broad and relativistic effects from near the innermost disk have to be included. Gravitationally broadened line fits also provide nearly edge-on angles of inclination consistent with the observed high dynamics near the Ne K edge. The emissions appear consistent with an ionized disk with ionization parameters of the order of 10 4 at radii of a few 10 7 cm. The line wavelengths with respect to O viii Ly α are found variably blueshifted indicating more complex inner disk dynamics.

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“…References. 1) Stella et al (1987); 2) Kuulkers et al (2003) White & Swank (1982); 38) Walter et al (1982); 39) Galloway et al (2008); 40) Becker et al (1977); 41) Lewin et al (1977); 42) Krimm et al (2007); 43) Altamirano et al (2010); 44) Ortolani et al (1994); 45) Galloway et al (2010); 46) Wilson-Hodge et al (2012); 47) Lewin et al (1976); 48) Hoffman et al (1976); 49) Strohmayer et al (1996); 50) Deutsch et al (2000); 51) in't Zand et al (1998); 52) Shahbaz et al (2008); 53) Hakala et al (2011); 54) Zhang et al (2012); 55) Kuulkers et al (2010); 56) Madej et al (2010); 57) Swank et al (1978); 58) Brandt et al (1992); 59) Ford et al (1997) Galactic plane. Table 1 presents an updated version of the UCXB and UCXB candidate overviews in in't Zand et al (2007), Lasota et al (2008) and Nelemans & Jonker (2010).…”

Section: Methodsunclassified

Long-term luminosity behavior of 14 ultracompact X-ray binaries

Haaften

Voss

Nelemans

2012

A&A

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Context. X-ray binaries are usually divided in persistent and transient sources. For ultracompact X-ray binaries (UCXBs), the mass transfer rate is expected to be a strong function of orbital period, predicting persistent sources at short periods and transients at long periods. Aims. For 14 UCXBs including two candidates, we investigate the long-term variability and average bolometric luminosity with the purpose of learning how often a source can be expected to be visible above a given luminosity, and we compare the derived luminosities with the theoretical predictions. Methods. We use data from the RXTE All-Sky Monitor because of its long-term, unbiased observations. Many UCXBs are faint, i.e., they have a count rate at the noise level for most of the time. Still, information can be extracted from the data, either by using only reliable data points or by combining the bright-end variability behavior with the time-averaged luminosity.Results. Luminosity probability distributions show the fraction of time that a source emits above a given luminosity. All UCXBs show significant variability and relatively similar behavior, though the time-averaged luminosity implies higher variability in systems with an orbital period longer than 40 min. Conclusions. There is no large difference in the statistical luminosity behavior of what we usually call persistent and transient sources. UCXBs with an orbital period below ∼30 min have a time-averaged bolometric luminosity that is in reasonable agreement with estimates based on the theoretical mass transfer rate. Around 40 min the lower bound on the time-averaged luminosity is similar to the luminosity based on the theoretical mass transfer rate, suggesting these sources are indeed faint when not detected. Above 50 min some systems are much brighter than the theoretical mass transfer rate predicts, unless these systems have helium burning donors or lose additional angular momentum.

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A relativistically broadened Oviii Lyα line in the ultracompact X-ray binary 4U 0614+091

Cited by 36 publications

References 27 publications

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries

Dynamical K Edge and Line Variations in the X-Ray Spectrum of the Ultra-Compact Binary 4u 0614+091

Long-term luminosity behavior of 14 ultracompact X-ray binaries

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