Very deep X-ray observations of the anomalous X-ray pulsar 4U 0142+614

Rea, N.; Nichelli, Elisa; Israel, G. L.; Perna, Rosalba; Oosterbroek, T.; Parmar, A. N.; Turolla, R.; Campana, S.; Stella, L.; Zane, S.; Angelini, L.

doi:10.1111/j.1365-2966.2007.12257.x

Cited by 46 publications

(48 citation statements)

References 52 publications

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“…This is in agreement with Rea et al (2007a) and Gonzalez et al (2008), however, Gonzalez et al (2008) report a flux increase of (15 ± 3)% (2−10 keV) between the epochs of our XMM-Newton observations A, B and C and the epochs after the bursting activities started in 2006. The flux levels around 10 keV of the three XMM-Newton spectra are rather similar.…”

Section: Xmm-newton Epic-pn Total Emission Spectrasupporting

confidence: 79%

“…We have also analysed the data from both MOS instruments and used this for consistency checks. The PN was in small-window mode during observation A and in timing mode during observations B and C. In parallel studies Rea et al (2007a) and Gonzalez et al (2008) also analysed these XMM-Newton observations. Gonzalez et al (2008) also included private XMM-Newton data taken in 2006 and 2007 together with Chandra and Swift data to study long-term variations below 10 keV.…”

Section: Xmm-newtonmentioning

confidence: 80%

“…From that work and e.g. Israel et al (1999); Dib et al (2007); Rea et al (2007a) it is clear that the pulse profiles significantly change morphology with energy. In Sect.…”

Section: Xmm-newton and Asca Pulse Profiles: Time Variabilitymentioning

confidence: 93%

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Detailed high-energy characteristics of AXP 4U 0142+61

Hartog¹,

Kuiper²,

Hermsen

et al. 2008

A&A

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ABSTRACT4U 0142+61 is one of the Anomalous X-ray Pulsars exhibiting hard X-ray emission above 10 keV discovered with INTEGRAL. In this paper we present detailed spectral and temporal characteristics both in the hard X-ray (>10 keV) and soft X-ray (<10 keV) domains obtained using data from INTEGRAL, XMM-Newton, ASCA and RXTE. Accumulating data collected over four years with the imager IBIS-ISGRI aboard INTEGRAL, the time-averaged total spectrum shows a power-law like shape with photon index Γ = 0.93 ± 0.06. 4U 0142+61 is detected up to 229 keV and the flux between 20 keV and 229 keV is (15.01 ± 0.82) × 10 −11 erg cm −2 s −1 , which exceeds the energy flux in the 2−10 keV band by a factor of ∼2.3. Using simultaneously collected data with the spectrometer SPI of INTEGRAL the combined total spectrum yields the first evidence for a spectral break above 100 keV. Assuming a logparabolic function for the spectral shape above 20 keV the peak energy of 4U 0142+61 is 228 +65 −41 keV. There is no evidence for significant long-term time variability of the total emission from 4U 0142+61. Both the total flux and the spectral index are stable within the 17% level (1σ). Pulsed emission is measured with ISGRI up to 160 keV. The 20−160 keV profile shows a broad double-peaked pulse with a 6.2σ detection significance. The total pulsed spectrum can be described with a very hard power-law shape with a photon index Γ = 0.40 ± 0.15 and a 20−150 keV flux of (2.68 ± 1.34) × 10 −11 erg cm −2 s −1 . To perform accurate phase-resolved spectroscopy over the total X-ray window, we produced pulse profiles in absolute phase for INTEGRAL-ISGRI, RXTE-PCA, XMM-Newton-PN and ASCA-GIS. The two known pulses in all soft X-ray profiles below 10 keV are located in the same phases. Three XMM-Newton observations in 2003−2004 show statistically identical profiles. However, we find a significant profile morphology change between an ASCA-GIS observation in 1999 following a possible glitch of 4U 0142+61. This change can be accounted for by differences in relative strengths and spectral shapes (0.8−10 keV) of the two pulses. The principle peak in the INTEGRAL pulse profile above 20 keV is located at the same phase as one of the pulses detected below 10 keV. The second pulse detected with INTEGRAL is slightly shifted with respect to the second peak observed in the soft X-ray band. We performed consistent phase-resolved spectroscopy over the total high-energy band and identify at least three genuinely different pulse components with different spectra. The high level of consistency between the detailed results from the four missions is indicative of a remarkably stable geometry underlying the emission scenario. Finally, we discuss the derived detailed characteristics of the high-energy emission of 4U 0142+61 in relation to three models for the non-thermal hard X-ray emission.

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Section: Xmm-newton Epic-pn Total Emission Spectrasupporting

confidence: 79%

Section: Xmm-newtonmentioning

confidence: 80%

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Detailed high-energy characteristics of AXP 4U 0142+61

Hartog¹,

Kuiper²,

Hermsen

et al. 2008

A&A

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“…This distortion is strongest in the high-energy spectral tail, where the intensity of the O-mode photons is larger for most viewing angles (see Figure 4). Observed enhancements of high-energy spectral tails are generally modeled with a power law (often of unknown origin; e.g., Manzali et al 2007 andDurant et al 2011 for young and middle-aged pulsars; Perna et al 2001, Juett et al 2002, and Rea et al 2007 for magnetars). However, a deficit of high-energy photons in a thermal fit could be a signature of photon-axion conversion, and the axion parameters could then be determined by means of detailed spectral fits that account for the effect.…”

Section: Observational Testsmentioning

confidence: 99%

Signatures of Photon-Axion Conversion in the Thermal Spectra and Polarization of Neutron Stars

Perna

Verde

et al. 2012

ApJ

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Conversion of photons into axions under the presence of a strong magnetic field can dim the radiation from magnetized astrophysical objects. Here we perform a detailed calculation aimed at quantifying the signatures of photon-axion conversion in the spectra, light curves, and polarization of neutron stars (NSs). We take into account the energy and angle dependence of the conversion probability and the surface thermal emission from NSs. The latter is computed from magnetized atmosphere models that include the effect of photon polarization mode conversion due to vacuum polarization. The resulting spectral models, inclusive of the general-relativistic effects of gravitational redshift and light deflection, allow us to make realistic predictions for the effects of photon to axion conversion on observed NS spectra, light curves, and polarization signals. We identify unique signatures of the conversion, such as an increase of the effective area of a hot spot as it rotates away from the observer line of sight. For a star emitting from the entire surface, the conversion produces apparent radii that are either larger or smaller (depending on axion mass and coupling strength) than the limits set by NS equations of state. For an emission region that is observed phase-on, photon-axion conversion results in an inversion of the plane of polarization with respect to the no-conversion case. While the quantitative details of the features that we identify depend on NS properties (magnetic field strength and temperature) and axion parameters, the spectral and polarization signatures induced by photon-axion conversion are distinctive enough to make NSs very interesting and promising probes of axion physics.

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“…2). In the case of 4U 0142+61, the 0.1-200 keV data are from XMM-Newton-PN and INTEGRAL-ISGRI (Rea et al 2007a;den Hartog et al 2008;Gonzalez et al 2010) plotted together with the 2σ COMPTEL upper limits (den Kuiper et al 2006). For 1E 2259+586 we show data points from XMMNewton-PN (Woods et al 2004) together with COMPTEL upper limits .…”

Section: Resultsmentioning

confidence: 99%

Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes

Aleksić

Antonelli

Antoranz

et al. 2012

A&A

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Context. Magnetars are an extreme, highly magnetized class of isolated neutron stars whose large X-ray luminosity is believed to be driven by their high magnetic field. Aims. We study for the first time the possible very high energy γ-ray emission above 100 GeV from magnetars, observing the sources 4U 0142+61 and 1E 2259+586. Methods. We observed the two sources with atmospheric Cherenkov telescopes in the very high energy range (E > 100 GeV). 4U 0142+61 was observed with the MAGIC I telescope in 2008 for about 25 h and 1E 2259+586 was observed with the MAGIC stereoscopic system in 2010 for about 14 h. The data were analyzed with the standard MAGIC analysis software. Results. Neither magnetar was detected. Upper limits to the differential and integral flux above 200 GeV were computed using the Rolke algorithm. We obtain integral upper limits to the flux of 1.52 × 10 −12 cm −2 s −1 and 2.7 × 10 −12 cm −2 s −1 with a confidence level of 95% for 4U 0142+61 and 1E 2259+586, respectively. The resulting differential upper limits are presented together with X-ray data and upper limits in the GeV energy range.

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Very deep X-ray observations of the anomalous X-ray pulsar 4U 0142+614

Cited by 46 publications

References 52 publications

Detailed high-energy characteristics of AXP 4U 0142+61

Detailed high-energy characteristics of AXP 4U 0142+61

Signatures of Photon-Axion Conversion in the Thermal Spectra and Polarization of Neutron Stars

Observations of the magnetars 4U 0142+61 and 1E 2259+586 with the MAGIC telescopes

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