X-ray properties of 4U 1543–624

Schultz, J.

doi:10.1051/0004-6361:20021477

Cited by 11 publications

(22 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We find that a wide, FWHM=2.64±0.14 keV, is allowed with a best-fit EW of 370±40 eV. This line is comparable to that found by Schultz (2002) in the RXTE data of 4U 1543−624. If the energy of the Gaussian is allowed to vary, the Gaussian model becomes even wider, FWHM≈6 keV, with a central energy of 4 keV.…”

Section: U 1543−624supporting

confidence: 85%

“…McClintock et al (1978) identified the optical counterpart of 4U 1543−624 based on the SAS-3 position, which was confirmed by HEAO 1. The flux measurements of 4U 1543−624 are roughly constant over the last 25 years (Singh, Apparao, & Kraft 1994;Christian & Swank 1997;Asai et al 2000;Juett et al 2001;Schultz 2002;Farinelli et al 2003) with no periodicities from 50 s -10,000 s found in the EXOSAT data, and no periodicities from 0.1 s -1000 s detected in the SAX data. Recently, Schultz (2002) presented spectral results from archival ASCA, SAX, and RXTE ob-servations.…”

Section: Introductionmentioning

confidence: 85%

See 1 more Smart Citation

X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

Juett

Chakrabarty

2003

ApJ

View full text Add to dashboard Cite

We present high-resolution spectroscopy of the neutron-star/low-mass X-ray binaries 2S 0918−549 and 4U 1543−624 with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory and the Reflection Grating Spectrometer onboard XMM-Newton. Previous lowresolution spectra of both sources showed a broad line-like feature at 0.7 keV that was originally attributed to unresolved line emission. We recently showed that this feature could also be due to excess neutral Ne absorption, and this is confirmed by the new high-resolution Chandra spectra. The Chandra spectra are each well fit by an absorbed power-law + blackbody model with a modified Ne/O number ratio of 0.52±0.12 for 2S 0918−549 and 1.5±0.3 for 4U 1543−624, compared to the interstellar-medium value of 0.18. The XMM spectrum of 2S 0918−549 is best fit by an absorbed power-law model with a Ne/O number ratio of 0.46±0.03, consistent with the Chandra result. On the other hand, the XMM spectrum of 4U 1543−624 is softer and less luminous than the Chandra spectrum and has a best-fit Ne/O number ratio of 0.54±0.03. The difference between the measured abundances and the expected interstellar ratio, as well as the variation of the column densities of O and Ne in 4U 1543−624, supports the suggestion that there is absorption local to these binaries. We propose that the variations in the O and Ne column densities of 4U 1543−624 are caused by changes in the ionization structure of the local absorbing material. It is important to understand the effect of ionization on the measured absorption columns before the abundance of the local material can be determined. This work supports our earlier suggestion that 2S 0918−549 and 4U 1543−624 are ultracompact binaries with Ne-rich companions.

show abstract

Section: U 1543−624supporting

confidence: 85%

Section: Introductionmentioning

confidence: 85%

X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

Juett

Chakrabarty

2003

ApJ

View full text Add to dashboard Cite

show abstract

“…In addition to O VIII Lyα, there was also evidence of a possible Fe Kα feature at ∼ 6.6 keV concurrent with the detection of O VIII Lyα (Madej & Jonker 2011). This was not the first time that the Fe line had been detected in this system, since it was present in prior RXTE and EXOSAT data (Schultz 2003), but Madej & Jonker (2011) were the first to claim that both features were present in the X-ray spectrum. The O VIII feature was found to be more intense relative to the continuum than Fe K. For a typical accretion disk of solar abundance, O VIII is the second strongest feature after Fe K. In order for O to be the most prominent feature, the disk would need a significant overabundance of oxygen (Ballantyne et al 2002), further supporting that the donor star in the system is a CO or ONe white dwarf (Madej & Jonker 2011).…”

Section: Introductionmentioning

confidence: 79%

“…Using an absorbed double thermal component model, TBABS*(DISKBB+BBODY), similar to Ng et al (2010), provides a reduced χ 2 ν = 3.51 and fails to model the INTE-GRAL component in interval E. If instead we use an absorbed power-law and blackbody model as per Juett & Chakrabarty (2003), this improves the fit to χ 2 ν = 2.11. If instead we use a Comptonization component, NTHCOMP, in place of the power-law similar to Schultz (2003), we obtain a comparable fit of χ 2 ν = 2.11 from TBABS*(NTHCOMP+BBODY), assuming that the seed photons originate from the accretion disk. Conversely, if we assume the seed photons originate from the blackbody component, TBABS*(NTHCOMP+DISKBB), then the fit becomes worse (χ 2 ν = 3.66).…”

Section: Spectralmentioning

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

View full text Add to dashboard Cite

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.

show abstract

“…Madej & Jonker (2011) have found that the continuum spectrum in the XMM-Newton data of 4U 1543−624 can be described by the combination of a disc black body with kT dbb ≈ 0.4 keV and powerlaw with a break around 6 keV. Schultz (2003) has also shown that the BeppoSAX and ASCA spectra of 4U 1543−624 can be described using a Comptonization model with a high optical depth and a black body (representing boundary layer emission) with kT bb ≈ 1.5 keV. These characteristics of the spectrum of 4U 1543−624 appear unusual for typical LMXBs, however, similar to the characteristics of spectra of ultra-luminous X-ray sources (ULXs) when observed in the ultraluminous state (Gladstone et al 2009).…”

Section: U 1543−624mentioning

confidence: 99%

X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

Madej¹,

Garcia²,

Jonker³

et al. 2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present spectroscopic X-ray data of two candidate ultra-compact X-ray binaries: 4U 0614+091 and 4U 1543−624. We confirm the presence of a broad O VIII Lyα reflection line (at ≈ 18 Å) using XMM-Newton and Chandra observations obtained in 2012 and 2013. The donor star in these sources is carbon-oxygen or oxygen-neon-magnesium white dwarf. Hence, the accretion disc is enriched with oxygen which makes the O VIII Lyα line particularly strong. We also confirm the presence of a strong absorption edge at ≈ 14 Å so far interpreted in the literature as due to absorption by neutral neon in the circumstellar and interstellar medium. However, the abundance required to obtain a good fit to this edge is ≈ 3 − 4 times solar, posing a problem for this interpretation. Furthermore, modeling the X-ray reflection off a carbon and oxygen enriched, hydrogen and helium poor disc with models assuming solar composition likely biases several of the best-fit parameters. In order to describe the Xray reflection spectra self-consistently we modify the currently available xillver reflection model. We present initial grids that can be used to model X-ray reflection spectra in UCXBs with carbon-oxygen-rich (and hydrogen and helium poor) accretion disc. We find that the new reflection model provides a better overall description of the reflection spectra of 4U 0614+091 and 4U 1543−624 than the reflection models that assume solar abundances. Besides a strong O VIII Lyα line the new reflection model also shows a strong O VIII K-edge (at 14.23 Å). We find that the absorption edge at ≈ 14 Å present in the data can be described by a O VIII K-edge formed due to reflection in the accretion disc and a Ne I K-edge originating mostly (if not entirely) in the interstellar medium, mitigating the problem of the apparent very high neon abundance. Additionally, based on the spectral properties of 4U 1543−624 we consider a scenario in which this source is accreting near the Eddington limit.

show abstract

X-ray properties of 4U 1543–624

Cited by 11 publications

References 33 publications

X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

X‐Ray Spectroscopy of the Low‐Mass X‐Ray Binaries 2S 0918−549 and 4U 1543−624: Evidence for Neon‐rich Degenerate Donors

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

X-ray reflection in oxygen-rich accretion discs of ultracompact X-ray binaries

Contact Info

Product

Resources

About