This project is based on the results published in the paper of Lutovinov & Tsygankov (2009). Its full version can be downloaded
here or through arXiv.|
This is the next work in our series of papers (Tsygankov et al. 2007; Lutovinov and Tsygankov 2008; Tsygankov et al. 2009) devoted to the investigation of the pulse profiles and pulsed fractions for X-ray pulsars. Using the methods proposed and described by Tsygankov et al. (2007), we investigated the ten (4U 0115+63, V 0332+53, A 0535+262, Vela X-1, Cen X-3, GX 301-2, OAO 1657-415, Her X-1, GX 1+4, EXO 2030+375) brightest (with fluxes >100 mCrab) X-ray pulsars based on INTEGRAL data in the hard (>20 keV) energy band. Here, we analyze in detail the dependence of the pulsed fraction for X-ray pulsars on their luminosity and energy band and the effect of resonance absorption near the cyclotron line on it for the first time. In addition, we obtained pulse profiles for the above pulsars in several energy bands, relative intensity maps of pulse profiles, and dependences of the pulsed fraction (PF) on energy for all of the possible observed states and luminosities and compiled the corresponding catalog. Since this is a fairly large data set and in order not to overload the paper, we provide there only the averaged (if the profile did not change significantly with luminosity) or most typical pulse profiles, intensity maps, and PF dependences on the energy.
Some useful information:
The IBIS data were processed for a timing analysis using software developed and maintained in the National Astrophysical Institute in Palermo, Italy (http://www.pa.iasf.cnr.it/~ferrigno/INTEGRALsoftware.html); a description of the data processing technique can be found in Segreto and Ferrigno (2007) and Mineo et al. (2006).
For each pulsar here you can find the result Table with next columns: (1) INTEGRAL observatory orbit numbers, (2) dates of observations (in MJD), (3) exposure times, (4) source fluxes, and (5) source luminosities (calculated by assuming the distance to the source to be known) in the 3-100 keV energy band. The distances to the objects under study were taken from the literature:
Our main results are the pulse profiles (column 7 for figure and columns 8-12 for data-files in QDP format) in wide energy channels (20-30, 30-40, 40-50, 50-70, 70-100 keV), the relative intensity maps in ``energy -- pulse phase'' coordinates from IBIS data (column 6), and the dependencies of PF (calculated as PF=(Imax-Imin)/(Imax+Imin), where Imax and Imin are the source intensities at the maximum and minimum of the pulse profile) on energy and luminosity. The intensity maps were obtained by convolving the pulsar light curve corrected for the background emission in narrow energy channels (the width was chosen to provide an optimal significance and was about 5 keV) whose centroid shifted from channel to channel by 2-3 keV. Each profile was constructed in units relative to the mean count rate in a given channel. We give the resulting map normalized to unity (all intensities were divided by the maximum value over the entire map). Such a representation reflects well the evolution of the profile structure (the change in the relative contribution of different peaks etc.).
This work was partially supported by RFBR grants 07-02-01051 and 08-08-13734.
|(c) Space Research Institute, Moscow, Russia, 2008.|