RXTE Proportional Counter Array Research Articles

Rapid X-ray variability of the gamma-ray binary LS I +61°303

ABSTRACT The gamma-ray binary LS I +61°303 has been widely monitored at different wavelengths since its discovery more than 60 yr ago. However, the nature of the compact object and the peculiar behaviour of the system are still largely debated. Aimed at investigating the rapid X-ray variability of LS I +61°303, we have analysed all the archival Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) data of the source, taken between 1996 and 2011. The timing analysis yields a periodicity of P ∼ 26.6 ± 0.3 d, which is statistically compatible with several periodicities reported in the literature for LS I +61°303. Using this period, we performed a data phase-resolved analysis to produce a set of phase-bin-averaged energy spectra and power density spectra. These power density spectra are dominated by weak red noise below 0.1 Hz, and show no signal above this frequency. The amplitude of the red noise varies mildly with the phase, and shows a maximum that coincides with a dip of the X-ray flux and a softer photon index. Aside from low-frequency noise, this analysis does not provide any statistically significant periodic or quasi-periodic timing feature in the RXTE/PCA data of LS I +61°303.

The Disk Wind in the Neutron Star Low-mass X-Ray Binary GX 13+1

Abstract We present the analysis of seven Chandra High Energy Transmission Grating Spectrometer and six simultaneous RXTE Proportional Counter Array observations of the persistent neutron star (NS) low-mass X-ray binary GX 13+1 on its normal and horizontal branches. Across nearly 10 years, GX 13+1 is consistently found to be accreting at 50%–70% Eddington, and all observations exhibit multiple narrow, blueshifted absorption features, the signature of a disk wind, despite the association of normal and horizontal branches with jet activity. A single absorber with standard abundances cannot account for all seven major disk wind features, indicating multiple absorption zones may be present. Two or three absorbers can produce all of the absorption features at their observed broadened widths and reveal that multiple kinematic components produce the accretion disk wind signature. Assuming the most ionized absorber reflects the physical conditions closest to the NS, we estimate a wind launching radius of 7 × 1010 cm, for an electron density of 1012 cm−3. This is consistent with the Compton radius and also with a thermally driven wind. Because of the source’s high Eddington fraction, radiation pressure likely facilitates the wind launching.

Properties of X-Ray Flux of Jets during the 2005 Outburst of Swift J1753.5−0127 Using the TCAF Solution

Abstract Galactic black hole candidate Swift J1753.5−0127 was discovered on 2005 June 30 by the Swift Burst Alert Telescope. We study the accretion flow properties during its very first outburst through careful analysis of the evolution of the spectral and the temporal properties using the two-component advective flow (TCAF) paradigm. RXTE proportional counter array spectra in are fitted with the current version of the TCAF model fits file to estimate physical flow parameters, such as two-component (Keplerian disk and sub-Keplerian halo) accretion rates, properties of the Compton cloud, probable mass of the source, etc. The source is found to be in harder (hard and hard-intermediate) spectral states during the entire phase of the outburst with very significant jet activity. Since in the TCAF solution the model normalization is constant for any particular source, any requirement of significantly different normalization to have a better fit on certain days would point to an X-ray contribution from components not taken into account in the current TCAF model fits file. By subtracting the contribution using actual normalization, we derive the contribution of X-rays from the jets and outflows. We study its properties, such as its magnitude and spectra. We find that on some days, up to about 32% of X-ray flux is emitted from the base of the jet itself.

ACCRETION FLOW DYNAMICS OF MAXI J1836-194 DURING ITS 2011 OUTBURST FROM TCAF SOLUTION

ABSTRACT The Galactic transient X-ray binary MAXI J1836-194 was discovered on 2011 August 29. Here we make a detailed study of the spectral and timing properties of its 2011 outburst using archival data from the RXTE Proportional Counter Array instrument. The evolution of accretion flow dynamics of the source during the outburst through spectral analysis with Chakrabarti–Titarchuk’s two-component advective flow (TCAF) solution as a local table model in XSPEC. We also fitted spectra with combined disk blackbody and power-law models and compared it with the TCAF model fitted results. The source is found to be in hard and hard-intermediate spectral states only during the entire phase of this outburst. No soft or soft-intermediate spectral states are observed. This could be due to the fact that this object belongs to a special class of sources (e.g., MAXI J1659-152, Swift J1753.5-0127, etc.) that have very short orbital periods and that the companion is profusely mass-losing or the disk is immersed inside an excretion disk. In these cases, flows in the accretion disk are primarily dominated by low viscous sub-Keplerian flow and the Keplerian rate is not high enough to initiate softer states. Low-frequency quasi-periodic oscillations (QPOs) are observed sporadically although as in normal outbursts of transient black holes, monotonic evolutions of QPO frequency during both rising and declining phases are observed. From the TCAF fits, we find the mass of the black hole in the range of 7.5–11 M ⊙, and from time differences between peaks of the Keplerian and sub-Keplerian accretion rates we obtain a viscous timescale for this particular outburst, ∼10 days.

AN EMPIRICAL METHOD FOR IMPROVING THE QUALITY OF RXTE HEXTE SPECTRA

ABSTRACT We have developed a correction tool to improve the quality of Rossi X-ray Timing Explorer (RXTE) High Energy X-ray Timing Experiment (HEXTE) spectra by employing the same method we used earlier to improve the quality of RXTE Proportional Counter Array (PCA) spectra. We fit all of the hundreds of HEXTE spectra of the Crab individually to a simple power-law model, some 37 million counts in total for Cluster A and 39 million counts for Cluster B, and we create for each cluster a combined spectrum of residuals. We find that the residual spectrum of Cluster A is free of instrumental artifacts while that of Cluster B contains significant features with amplitudes ∼1%; the most prominent is in the energy range 30–50 keV, which coincides with the iodine K edge. Starting with the residual spectrum for Cluster B, via an iterative procedure we created the calibration tool hexBcorr for correcting any Cluster B spectrum of interest. We demonstrate the efficacy of the tool by applying it to Cluster B spectra of two bright black holes, which contain several million counts apiece. For these spectra, application of the tool significantly improves the goodness of fit, while affecting only slightly the broadband fit parameters. The tool may be important for the study of spectral features, such as cyclotron lines, a topic that is beyond the scope of this paper.

DOES THE 62-DAY X-RAY PERIODICITY COME FROM ULX M82 X-1?

M82 X-1 is the brightest ultraluminous X-ray source in starburst galaxy M82 and is one of the best intermediate mass black hole candidates. Previous studies based on the Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) reported a regular X-ray flux modulation of M82 with a period of 62 days, and attributed this periodic modulation to M82 X-1. However, this modulation is not necessarily from M82 X-1 because RXTE/PCA has a very poor spatial resolution of ~1 degree. In this work, we analyzed 1000 days of monitoring data of M82 X-1 from the Swift/X-ray telescope (XRT), which has a much better spatial resolution than RXTE/PCA. The periodicity distribution map of M82 reveals that the 62-day periodicity is most likely not from M82 X-1, but from the summed contributions of several periodic X-ray sources 4 arcsec southeast of M82 X-1. However, Swift/XRT is not able to resolve those periodic sources and locate the precise origin of the periodicity of M82. Thus, more long-term observations with higher spatial resolution are required.

ACCRETION FLOW DYNAMICS OF MAXI J1659-152 FROM THE SPECTRAL EVOLUTION STUDY OF ITS 2010 OUTBURST USING THE TCAF SOLUTION

Transient black hole candidates are interesting objects to study in X-rays as these sources show rapid evolutions in their spectral and temporal properties. In this paper, we study the spectral properties of the Galactic transient X-ray binary MAXI~J1659-152 during its very first outburst after discovery with the archival data of RXTE Proportional Counter Array instruments. We make a detailed study of the evolution of accretion flow dynamics during its 2010 outburst through spectral analysis using the Chakrabarti-Titarchuk two-component advective flow (TCAF) model as an additive table model in XSPEC. Accretion flow parameters (Keplerian disk and sub-Keplerian halo rates, shock location and shock strength) are extracted from our spectral fits with TCAF. We studied variations of these fit parameters during the entire outburst as it passed through three spectral classes: hard, hard-intermediate, and soft-intermediate. We compared our TCAF fitted results with standard combined disk black body (DBB) and power-law (PL) model fitted results and found that variations of disk rate with DBB flux and halo rate with PL flux are generally similar in nature. There appears to be an absence of the soft state unlike what is seen in other similar sources.

Detection of a variable QPO at ∼41 mHz in the Be/X-ray transient pulsar 4U 0115+634

We report the detection of quasi-periodic oscillation (QPO) at ~41 mHz in the transient high-mass Be/X-ray binary pulsar 4U~0115+634 using data from the Rossi X-Ray Timing Explorer (RXTE) observatory. The observations used in the present work were carried out during X-ray outbursts in 1999 March-April, 2004 September-October and 2008 March-April. This frequency of the newly detected QPO was found to vary in 27-46 mHz range. This ~41 mHz QPO was detected in four of the 36 pointed RXTE Proportional Counter Array (PCA) observations during 1999 outburst where as during 2004 and 2008 outbursts, it was detected in four and three times out of 33 and 26 observations, respectively. Though QPOs at ~2 mHz, and ~62 mHz were reported earlier, the ~41 mHz QPO and its first harmonic were detected for the first time in this pulsar. There are three RXTE/PCA observations where multiple QPOs were detected in the power density spectrum of 4U~0115+634. Simultaneous presence of multiple QPOs is rarely seen in accretion powered X-ray pulsars. Spectral analysis of all the pointed RXTE/PCA observations revealed that the 3-30 keV energy spectrum was well described by Negative and Positive Power-law with EXponential cutoff (NPEX) continuum model along with interstellar absorption and cyclotron absorption components. During the three X-ray outbursts, however, no systematic variation in any of the spectral parameters other than the earlier reported anti-correlation between cyclotron absorption energy and luminosity was seen. Presence of any systematic variation of QPO frequency and rms of QPO with source flux were also investigated yielding negative results.

GALACTIC ULTRACOMPACT X-RAY BINARIES: EMPIRICAL LUMINOSITIES

Ultracompact X-ray binaries (UCXBs) are thought to have relatively simple binary evolution post-contact, leading to clear predictions of their luminosity function. We test these predictions by studying the long-term behavior of known UCXBs in our Galaxy, principally using data from the MAXI All-Sky Survey and the Galactic bulge scans with RXTE's Proportional Counter Array instrument. Strong luminosity variations are common (and well documented) among persistent UCXBs, which requires an explanation other than the disk instability mechanism. We measure the luminosity function of known UCXBs in the Milky Way, which extends to lower luminosities than some proposed theoretical luminosity functions of UCXBs. The difference between field and globular cluster (GC) X-ray luminosity functions in other galaxies cannot be explained by an increased fraction of UCXBs in GCs. Instead, our measured luminosity function suggests that UCXBs only make up a small fraction of the X-ray binaries above a few × 1036 erg s−1 in both old field populations and GCs.

Timing accuracy of theSwiftX-Ray Telescope in WT mode

The X-Ray Telescope (XRT) on board Swift was mainly designed to provide detailed position, timing and spectroscopic information on Gamma-Ray Burst (GRB) afterglows. During the mission lifetime the fraction of observing time allocated to other types of source has been steadily increased. In this paper, we report on the results of the in-flight calibration of the timing capabilities of the XRT in Windowed Timing read-out mode. We use observations of the Crab pulsar to evaluate the accuracy of the pulse period determination by comparing the values obtained by the XRT timing analysis with the values derived from radio monitoring. We also check the absolute time reconstruction measuring the phase position of the main peak in the Crab profile and comparing it both with the value reported in literature and with the result that we obtain from a simultaneous Rossi X-Ray Timing Explorer (RXTE) observation. We find that the accuracy in period determination for the Crab pulsar is of the order of a few picoseconds for the observation with the largest data time span. The absolute time reconstruction, measured using the position of the Crab main peak, shows that the main peak anticipates the phase of the position reported in literature for RXTE by ~270 microseconds on average (~150 microseconds when data are reduced with the attitude file corrected with the UVOT data). The analysis of the simultaneous Swift-XRT and RXTE Proportional Counter Array (PCA) observations confirms that the XRT Crab profile leads the PCA profile by ~200 microseconds. The analysis of XRT Photodiode mode data and BAT event data shows a main peak position in good agreement with the RXTE, suggesting the discrepancy observed in XRT data in Windowed Timing mode is likely due to a systematic offset in the time assignment for this XRT read out mode.

The discovery of the 401 Hz accreting millisecond pulsar IGR J17498-2921 in a 3.8 h orbit

We report on the detection of a 400.99018734(1) Hz coherent signal in the Rossi X-ray Timing Explorer light curves of the recently discovered X-ray transient, IGR J17498-2921. By analysing the frequency modulation caused by the orbital motion observed between August 13 and September 8, 2011, we derive an orbital solution for the binary system with a period of 3.8432275(3) hr. The measured mass function, f(M_2, M_1, i)=0.00203807(8) Msun, allows to set a lower limit of 0.17 Msun on the mass of the companion star, while an upper limit of 0.48 Msun is set by imposing that the companion star does not overfill its Roche lobe. We observe a marginally significant evolution of the signal frequency at an average rate of -(6.3 +/- 1.9)E-14 Hz/s. The low statistical significance of this measurement and the possible presence of timing noise hampers a firm detection of any evolution of the neutron star spin. We also present an analysis of the spectral properties of IGR J17498-2921 based on the observations performed by the Swift-X-ray Telescope and the RXTE-Proportional Counter Array between August 12 and September 22, 2011. During most of the outburst, the spectra are modeled by a power-law with an index Gamma~1.7-2, while values of ~3 are observed as the source fades into quiescence.

X-ray softening in the new X-ray transient XTE J1719−291 during its 2008 outburst decay

The X-ray transient XTE J1719−291 was discovered with Rossi X-ray Timing Explorer/Proportional Counter Array (RXTE/PCA) during its outburst in 2008 March, which lasted at least 46 d. Its 2–10 keV peak luminosity is 7 × 1035 erg s−1 assuming a distance of 8 kpc, which classifies the system as a very faint X-ray transient. The outburst was monitored with Swift, RXTE, Chandra and XMM–Newton. We analysed the X-ray spectral evolution during the outburst. We fitted the overall data with a simple power-law model corrected for absorption and found that the spectrum softened with decreasing luminosity. However, the XMM–Newton spectrum cannot be fitted with a simple one-component model, but it can be fitted with a thermal component (blackbody or disc blackbody) plus a power-law model affected by absorption. Therefore, the softening of the X-ray spectrum with decreasing X-ray luminosity might be due to a change in photon index or alternatively it might be due to a change in the properties of the soft component. Assuming that the system is an X-ray binary, we estimated a long-term time-averaged mass accretion rate of ∼ 7.7 × 10−13 M⊙ yr−1 for a neutron star as a compact object and ∼ 3.7 × 10−13 M⊙ yr−1 in the case of a black hole. Although no conclusive evidence is available about the nature of the accretor, based on the X-ray/optical luminosity ratio we tentatively suggest that a neutron star is present in this system.

THE LIGHT CURVE OF HERCULES X-1 AS OBSERVED BY THEROSSI X-RAY TIMING EXPLORER

Analysis of the light curve of Hercules X-1 using the full set of archival observations of Hercules X-1 by the Rossi X-Ray Timing Explorer/Proportional Counter Array (RXTE/PCA) is reported. The observations cover time periods that Her X-1 is in main high, short high, and low states, and an anomalous low state (ALS). They include over 1.4 Ms of net exposure time. We present 35 day and orbital phase folded light curves of the count rates and softness ratios, showing the range of behaviors of Her X-1 with the high sensitivity of the RXTE/PCA. New phenomena are uncovered and previous phenomena are seen in greater detail. For both main high and short high states, the fraction of time in dips is found to be a function of orbital phase and of 35 day phase. It increases steadily with orbital phase past orbital phase 0.3 and is higher at the start and end of both main high and short high states. It is higher for short high state (62%) than for main high state (28%). The normal low state data and ALS data are compared: the low state count rate is ~twice as high as for ALS data. The 2-4 keV to 9-20 keV softness ratio changes smoothly with orbital phase for low states and ALSs, and is indistinguishable between the two, yet very different than for the high states. This supports models for which the cause of the ALS is changed disk geometry that prevents a direct line of sight from neutron star to observer at all 35 day phases.

Bayesian timing analysis of giant flare of SGR 180620 by RXTE PCA

By detecting high frequency quasi-periodic oscillations (QPOs) and estimating frequencies of them during the decaying tail of giant flares from Soft Gamma-ray Repeaters (SGRs) useful constraints for the equation of state (EoS) of superdense matter may be obtained via comparison with theoretical predictions of eigenfrequencies. We used the data collected by the Rossi X-Ray Timing Explorer (RXTE/XTE) Proportional Counter Array (PCA) of a giant flare of SGR 1806-20 on 2004 Dec 27 and applied a Bayesian periodicity detection method (Gregory & Loredo, 1992) for the search of oscillations of transient nature. In addition to the already detected frequencies, we found a few new frequencies (f_{QPOs} ~ 16.9, 21.4, 36.4, 59.0, 116.3 Hz) of oscillations predicted by Colaiuda et al. (2009) based on the APR_{14} EoS (Akmal et al., 1998) for SGR 1806-20.

WHEN A STANDARD CANDLE FLICKERS

The Crab Nebula is the only hard X-ray source in the sky that is both bright enough and steady enough to be easily used as a standard candle. As a result, it has been used as a normalization standard by most X-ray/gamma ray telescopes. Although small-scale variations in the nebula are well-known, since the start of science operations of the Fermi Gamma-ray Burst Monitor (GBM) in August 2008, a ~ 7% (70 mcrab) decline has been observed in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline is independently confirmed with three other instruments: the Swift Burst Alert Telescope (Swift/BAT), the Rossi X-ray Timing Explorer Proportional Counter Array (RXTE/PCA), and the INTErnational Gamma-Ray Astrophysics Laboratory Imager on Board INTEGRAL (IBIS). A similar decline is also observed in the ~3 - 15 keV data from the RXTE/PCA and INTEGRAL Joint European Monitor (JEM-X) and in the 50 - 100 keV band with GBM and INTEGRAL/IBIS. Observations from 100 to 500 keV with GBM suggest that the decline may be larger at higher energies. The pulsed flux measured with RXTE/PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a ~3 year timescale are also seen independently with the PCA, BAT, and IBIS from 2005 to 2008, with a flux minimum in April 2007. As of August 2010, the current flux has declined below the 2007 minimum.

Flares, broadening of the pulse-frequency peak and quasi-periodic oscillations in the transient X-ray pulsar 4U 1901+03

After a long quiescence of three decades, the transient X-ray pulsar 4U 1901+03 became highly active in 2003 February. From the analysis of a large number of Rossi X-ray Timing Explorer/ Proportional Counter Array (RXTE/PCA) observations of this source, we report here the detection of X-ray flares, a broadening of the pulse frequency peak and Quasi Periodic Oscillations (QPOs). The X-ray flares showed spectral changes, had a duration of 100 s - 300 s, and were more frequent and stronger during the peak of the outburst. In most of the observations during the outburst we also detected a broadening of the pulse frequency peak. We have also found intensity dependent changes in the pulse profile at very short timescales. This reveals a coupling between the periodic and the low frequency aperiodic variabilities. In addition, near the end of the outburst we have detected a strong QPO feature centered at ~ 0.135 Hz. The QPO feature is broad with a quality factor of 3.3 and with an rms value of 18.5+/-3.1%. Using the QPO frequency and the X-ray luminosity during the QPO detection period we estimated the magnetic field strength of the neutron star as 0.31*10^12 G which is consistent with the value inferred earlier under the assumption of spin equilibrium.

EXTREME ULTRAVIOLET EXPLOREROBSERVATIONS OF HERCULES X-1 OVER A 35 DAY CYCLE

Observations of Hercules X-1 by the Extreme Ultraviolet Explorer covering most of the 35 day cycle are reported here. This is the only long extreme ultraviolet (EUV) observation of Her X-1. Simultaneous X-ray observations with the Rossi X-ray Timing Explorer All-Sky Monitor (RXTE/ASM) X-ray show that Her X-1 is in an X-ray anomalous low state. The first 4 days are also observed with the RXTE proportional counter array (PCA), which shows that the X-ray properties are nearly the same as for normal low states in Her X-1 with flux reduced by a factor of 2. In contrast, the EUV emission from Her X-1 is reduced by a factor of ∼4 compared to normal low states. The twisted-tilted accretion disk responsible for the normal 35 day X-ray cycle can be modified to explain this behavior. An increased disk twist reduces the X-ray illumination of HZ Her by a factor of ∼2 and of the disk surface by a somewhat larger factor, leading to a larger reduction in EUV flux compared to X-ray flux.

Study of 23 day periodicity of Blazar Mkn501 in 1997

We confirm a 23 day periodicity during a large flare in 1997 for X-ray data of X-ray satellite RXTE all sky monitor (ASM), 2 TeV gamma ray data from Utah Seven Telescope and HEGRA, with a Fourier analysis. We found the three results to be the same with a newly estimated error. We confirm the presence of a frequency dependent power (1/ f noise) in a frequency–power diagram. Further, we calculated a chance probability of the occurrence of the 23 day periodicity by considering the 1/ f noise and obtained a chance probability 4.88 × 10 −3 for the HEGRA data: this is more significant than the previous result by an order. We also obtained an indentical periodicity with another kind of timing analysis–epoch folding method for the ASM data and HEGRA data. We strongly suggest an existence of the periodicity. We divided the HEGRA data into two data sets, analyzed them with a Fourier method, and found an unstableness of the periodicity with a 3.4 sigma significance. We also analyzed an energy spectra of the X-ray data of a RXTE proportional counter array and we found that a combination of three physical parameters—a magnetic field, a Lorentz factor, and a beaming factor—is related to the periodicity.

Chandra and RXTE spectroscopy of the accreting msec pulsar IGR J00291+5934

We report on an observation of the recently discovered accreting millisecond X-ray pulsar IGR J00291+5934 performed with the RXTE-Proportional Counter Array (PCA) and Chandra-High Energy Transmission Grating Spectrometer (HETGS). The RXTE data are from a twoweek follow-up of the source, while the Chandra observation took place around the end of the follow-up, about 12 days after the discovery of the source, when the source flux had decreased already by a factor of ten. The analysis of the Chandra data allowed us to extract the most precise X-ray position of IGR J00291+5934, RA = 00h 29m 03.08s, and Dec =+59◦ 34 19.2 (0.6 error), compatible with the optical and radio ones. We find that the spectra of IGR J00291+5934 can be described by a combination of a thermal component and a power-law. Along the outburst detected by PCA, the power-law photon index showed no particular trend, while the thermal component (∼1 keV, interpreted as a hot spot on the neutron star surface) became weaker until non-detection. In the simultaneous observation of the weak Chandra /RXTE spectrum, there was no longer any indication of the ∼1 keV thermal component, while we detected a colder thermal component (∼0.4 keV) that we interpret as the emission from the cold disc. A hint of a 6.4 keV iron line was detected, together with an excess around 6.8 keV and absorption feature around 7.1 keV. The last two features have never been detected in the spectra of accretion-driven millisecond pulsars before and, if confirmed, would suggest the presence of an expanding hot corona with high outflow velocities.

X‐Ray Emission and Optical Polarization of V1432 Aquilae: An Asynchronous Polar

A detailed analysis of X-ray data obtained with ROSAT, ASCA, XMM-Newton, and the Rossi X-ray Timing Explorer (RXTE) for the asynchronous polar V1432 Aquilae is presented. An analysis of Stokes polarimetry data obtained from the South African Astronomical Observatory (SAAO) is also presented. Power spectra from long-baseline ROSAT data show a spin period of 12,150 s along with several frequency components related to the source. However, the second harmonic of the spin period dominates the power spectrum in the XMM-Newton data. For the optical circular polarization, the dominant period corresponds to half the spin period (or its first harmonic). The ROSAT data can be explained as due to accretion onto two hot spots that are not antipodal. The variations seen in the optical polarization and the ASCA and XMM-Newton X-ray data suggest the presence of at least three accretion footprints on the surface of the white dwarf. Two spectral models, a multitemperature plasma model and a photoionized plasma model, are used to understand the spectral properties of V1432 Aql. The data from the RXTE Proportional Counter Array (PCA) with its extended high-energy response are used to constrain the white dwarf mass to 1.2 ± 0.1 Mo using a multitemperature plasma model. The data from the European Photon Imaging Camera (EPIC) on-board XMM-Newton are well fitted by both models. A strong soft X-ray excess (<0.8 keV) is well modeled by a blackbody component having a temperature of 80–90 eV. The plasma emission lines seen at 6.7 and 7.0 keV are well fitted using the multitemperature plasma model. However, the fluorescent line at 6.4 keV from cold Fe requires an additional Gaussian component. The multitemperature plasma model requires two absorbers: one that covers the source homogeneously and another partial absorber covering ∼65% of the source. The photoionized plasma model, with a range of column densities for the Fe ions, gives a slightly better overall fit and fits all emission line features. The intensity and spectral modulations due to the rotation of the white dwarf at a period of 12,150 s require varying absorber densities and a varying covering fraction of the absorber for the multitemperature plasma model. The presence of a strong blackbody component, a rotation period of 12,150 s, modulation of the Fe fluorescence line flux with 12,150 s period, and a very hard X-ray component suggest that V1432 Aql is an unusual polar with X-ray spectral properties similar to that of a soft intermediate polar.