Possible evolution of dim radio quiet neutron star 1E 1207.4-5209 based on a B-decay model

Dim radio-quiet neutron star (DRQNS) 1E 1207.4-5209 is one of the most heavily examined isolated neutron stars. Wide absorption lines were observed in its spectrum obtained by both XMM-Newton and Chandra X-ray satellites. These absorption lines can be interpreted as a principal frequency centered at 0.7 keV and its harmonics at 1.4, 2.1 and possibly 2.8 keV. The principal line can be formed by resonant proton cyclotron scattering leading to a magnetic field which is two orders of magnitude larger than the perpendicular component of the surface dipole magnetic field (B) found from the rotation period (P) and the time rate of change in the rotation period (\.{P}) of 1E 1207.4-5209. Besides, age of the supernova remnant (SNR) G296.5+10.0 which is physically connected to 1E 1207.4-5209 is two orders of magnitude smaller than the characteristic age ($\tau$=P/2\.{P}) of the neutron star. These huge differences between the magnetic field values and the ages can be explained based on a B-decay model. If the decay is assumed to be exponential, the characteristic decay time turns out to be several thousand years which is three orders of magnitude smaller than the characteristic decay time of radio pulsars represented in an earlier work. The lack of detection of radio emission from DRQNSs and the lack of point sources and pulsar wind nebulae in most of the observed SNRs can also be partly explained by such a very rapid exponential decay. The large difference between the characteristic decay times of DRQNSs and radio pulsars must be related to the differences in the magnetic fields, equation of states and masses of these isolated neutron stars.Comment: 13 pages, 1 figur

X-ray Picture of Superclusters of Galaxies

Galaxies gravitationally attract each other and form galaxy groups (similar to 50) or galaxy clusters (> 100). Nevertheless galaxy clusters are not the end of structure formation. Clusters further get together and form Superclusters. Recent studies have shown that the Universe forms cosmic filaments and voids. The superclusters are the intersection points of these filaments. In this work we present an analysis of SCC100 and Shapley supercluster members. Using X-ray data we try to understand the mutual interactions between individual clusters. Since they are the best representatives of the Universe, we try to address large scale properties of the universe

PROBING THE COSMIC FILAMENTS BY MEANS OF X-RAY OBSERVATIONS

Recent observations and numerical simulations show that galaxies are not distributed in the Universe randomly. They are placed like the pearls of a necklace. The matter is spread into the space in the form of cosmic filaments and voids. The intersection regions of these cosmic filaments are what we observe as "clusters of galaxies". In this work we selected 9 clusters of galaxies (A1644, A1736, A3528, A3530, A3532, A3556, A3558, A3560, A3562) from SHAPLEY super cluster region, the largest concentration of galaxies in our nearby Universe. The XMM-Newton and Chandra archival data are used for the analysis. We interpret the morphology of the clusters in the region and gravitational perturbations as a result of close encountering in the Shapley. The cosmic filaments and webs are portrayed from the Shapley super cluster region analysis results

STRUCTURAL ANALYSIS OF A2034 CLUSTERS OF GALAXIES

We present the analysis of X-ray and optical observations of Abell 2034. It is located at the moderate redshift of z=0.113. X-ray data are taken from the XMM-Newton archive. The best-fit single temperature of 7.6 keV model well defines the diffuse hot plasma. The cluster is observed by ground based optical Turkish National Observatory RTT-150 telescope. X-ray spectra of the individual sources from the cluster outskirts are studied. The intra cluster medium (ICM) temperature and metal distributions are constructed using wavelet algorithms. We explore the morphology and dynamical history of the cluster based on our multi-wavelength analysis results

Structural Analysis of Abell 3560 Cluster of Galaxies

In this work we study the A3560 cluster, which is located at the Shapley concentration core close to A3562 and A2558 (< 8 Mpc). Imaging analysis shows that the X-ray brightness is elliptical. The elongation is in the south-east to north-west direction which is the direction to A3558. This is interpreted as the mutual interaction of clusters in high density super-cluster regions of the sky. The ICM physical properties and distributions are studied by newly developed spectral mapping algorithms. The temperature and metal abundance maps show small scale variations. The coldest north-west peak has also the lowest metal abundance value which is a strong indicator of a recent sub-group merger with different physical properties

Search for dark matter in clusters of galaxies

Clusters of galaxies have an exceptional place in the chain of structural formation. They are&nbsp;the largest gravitational entities and the best of cosmic laboratories. Their mass is orders of&nbsp;magnitude higher than the Jeans mass scale (&asymp; 1015 M ), and hence still preserve the knowledge&nbsp;of early universe baryon and dark matter mixture (fgas = Mgas/Mtot &asymp; ?b/?M) as the clusters&nbsp;grow from large-scale structures. The assumption of an extended isothermal gas sitting in&nbsp;hydrostatic equilibrium is used to estimate the M &minus;T relation. We described the temperature,&nbsp;density, and pressure of the intra-cluster medium and measured the cluster gas mass fraction&nbsp;for our moderately large sample.</p

DYNAMICS OF FAINT CLUSTERS OF GALAXIES

Recent studies with high-resolution cameras have extensively showed that clusters of galaxies are not as relaxed as we assumed. With its advent technology XMM-Newton allows us to obtain the temperature and metal abundance map in detail. In this study, we present our results related to six (A194, A1056, A1674, A1882, A2634, A2638) nearby (z<0.14) clusters. These clusters have very poor X-ray atmosphere (ICM) and therefore it is very efficient to study individual galaxies and their evolution within ICM. Based on the temperature maps and morphology of bright member galaxies, we try to understand the perturbed galaxy emissions and dynamics of the clusters itself

Suzaku Analysis of Galactic Supernova Remnants G27.4+0.0 and G12.0-0.1

We present Suzaku results of galactic supernova remnants (SNRs) G27.4 +0.0 and G12.0-0.1. From the spectra some important parameters like galactic hydrogen column density (N-H), electron temperature (kT(e)), ionization timescale (n(e)t) are calculated. Furthermore, the abundances of Mg, Si, S are derived from the spectra of G27.4+0.0 indicating that G27.4+0.0 has originated from a core-collapse supernova explosion

TURKISH NATIONAL OBSERVATORY (TUG) VIEW OF CLUSTERS OF GALAXIES

We present the results of the optical observations of clusters of galaxies trough photometric observations with RTT150 telescope. We have selected a sample of 10 nearby (z < 1.2) Abell clusters from the northern sky. Properties of the extended X-ray intra-cluster medium (ICM) are studied using Chandra and XMM-Newton archival data. Considering possible relations of X-ray and radio plasma, the extended radio halo and jets are studied. The intent of our observations is to map galaxy densities in the optical band and to define sub-clustering if there is any. The X-ray (temperature and metal distributions) and radio features, combined with galaxy distributions are used to diagnose morphology, structure and evolutional history of the clusters