Phase-resolved X-ray spectroscopy of PSR B0656+14 with SRG/eROSITA and XMM-Newton

Abstract

(abridged version) We present a detailed spectroscopic and timing analysis of X-ray observations of the bright radio-to-gamma-ray emitting pulsar PSR B0656+14, which were obtained simultaneously with eROSITA and XMM-Newton during the Calibration and Performance Verification phase of the Spektrum-Roentgen-Gamma mission (SRG) for 100 ks. Using XMM-Newton and NICER we firstly established an X-ray ephemeris for the time interval 2015 to 2020, which connects all X-ray observations in this period without cycle count alias and phase shifts. The mean eROSITA spectrum clearly reveals an absorption feature originating from the star at 570 eV with a Gaussian sigma of about 70 eV, tentatively identified earlier in a long XMM-Newton observation (Arumugasamy et al. 2018). A second absorption feature, described here as an absorption edge, occurs at 260-265 eV. It could be of atmospheric or of instrumental origin. These absorption features are superposed on various emission components, phenomenologically described as the sum of hot (120 eV) and cold (65 eV) blackbody components, both of photospheric origin, and a power-law with photon index Gamma=2. The phase-resolved spectroscopy reveals that the Gaussian absorption line at 570 eV is clearly present throughout ~60% of the spin cycle. The visibility of the line strength coincides in phase with the maximum flux of the hot blackbody. We also present three families of model atmospheres: a magnetised atmosphere, a condensed surface, and a mixed model, which were applied to the mean observed spectrum and whose continuum fit the observed data well. The atmosphere model, however, predicts too short distances. For the mixed model, the Gaussian absorption may be interpreted as proton cyclotron absorption in a field as high as 10^14 G, which is significantly higher than that derived from the moderate observed spin-down.

Submitted to A&A for the Special Issue: The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the SRG Mission. 21 pages, 13 figures, 13 tables

References in corpus (17)

• The eROSITA X-ray telescope on SRG
• The eROSITA Final Equatorial Depth Survey (eFEDS): The X-ray catalog
• Magnetars: Properties, Origin and Evolution
• Precise Gamma-Ray Timing and Radio Observations of 17 Fermi Gamma-Ray Pulsars
• Magnetic Hydrogen Atmosphere Models and the Neutron Star RX J1856.5-3754
• Polarimetry of 600 pulsars from observations at 1.4 GHz with the Parkes radio telescope
• The UTMOST pulsar timing programme II: Timing noise across the pulsar population
• A dedicated Chandra ACIS observation of the central compact object in the Cassiopeia A supernova remnant
• X-ray spectra and polarization from magnetar candidates
• Magneto-thermal evolution of neutron stars with coupled Ohmic, Hall and ambipolar effects via accurate finite-volume simulations
• Spectral features in isolated neutron stars induced by inhomogeneous surface temperatures
• Establishing the X-ray Source Detection Strategy for eROSITA with Simulations
• XMM-Newton RGS spectrum of RX J0720.4-3125: An absorption feature at 0.57 keV
• A deep XMM-Newton look on the thermally emitting isolated neutron star RX J1605.3+3249
• Radiative properties of highly magnetized isolated neutron star surfaces and approximate treatment of absorption features in their spectra
• Middle aged $\gamma$-ray pulsar J1957+5033 in X-rays: pulsations, thermal emission and nebula
• PSR B0656+14: the unified outlook from the infrared to X-rays

Cited by in corpus (5)

• XMM-Newton and SRG/eROSITA observations of the isolated neutron star candidate 4XMM J022141.5-735632
• Disclosing the catalog pulsars dominating the Galactic positron flux
• On the origin of the X-ray emission surrounding PSR B0656+14 in the eROSITA Cal-PV data
• XMM-Newton observations of PSR J0554+3107: pulsing thermal emission from a cooling high-mass neutron star
• Possible evidence for extended X-ray emission surrounding PSR B0656+14 with eROSITA