Search Publications
INTEGRAL constraints on the Galactic hard X-ray background from the Milky Way anticenter
Sunyaev, R.; Krivonos, R.; Tsygankov, S. +3 more
We present results of a study of the Galactic ridge X-ray emission (GRXE) in hard X-rays with the IBIS telescope onboard INTEGRAL in the region near the Galactic anticenter (GA) at l = 155°. We assumed a conservative 2σ upper limit on the flux from the GA in the 25-60 keV energy band of 1.25 × 10-10 erg s-1 cm-2 (1…
Deprojected analysis of Abell 1835 observed with Chandra and compared with XMM-Newton
Chen, Y.; Li, C. K.; Jia, S. M. +3 more
Using a deprojection technique, we study the X-ray properties of the galaxy cluster Abell 1835 observed with Chandra, including temperature, abundance, electron density, gas mass fraction, and total mass. A comparison with the results without deprojection shows that the properties do not change much. When we compare the results with those of XMM-N…
Properties of dust at the Galactic center probed by AKARI far-infrared spectral mapping. Detection of a dust feature
Takahashi, H.; Nakagawa, T.; Okada, Y. +5 more
Aims: We investigate the properties of interstellar dust in the Galactic center region toward the Arches and Quintuplet clusters.
Methods: With the Fourier Transform Spectrometer of the AKARI/Far-Infrared Surveyor, we performed the far-infrared (60-140 cm-1) spectral mapping of an area of about 10' × 10' that includes both clu…
The area asymmetry in bipolar magnetic fields
Yamamoto, T. T.
Context. The area asymmetry between the preceding and following regions of opposite magnetic polarity in a bipolar sunspot group has been known since the studies of Hale and his colleagues in the early 20th century. This area asymmetry, however, has not yet been investigated quantitatively using magnetograms.
Aims: We quantitatively define th…
Angular fluctuations in the CXB: is Fe 6.4 keV line tomography of the large-scale structure feasible?
Sunyaev, R.; Gilfanov, M.; Hütsi, G.
Context. Active galactic nuclei (AGN) are known to account for a major portion, if not all, of the cosmic X-ray background (CXB) radiation. The dominant sharp spectral feature in their spectra is the 6.4 keV fluorescent line of iron, which may contribute to as much as ~5-10% of the CXB spectral intensity at ~2-6 keV. Owing to cosmological redshift…
A new visual - near-infrared diagnostic to estimate the metallicity of cluster and field dwarf stars
Milone, A. P.; Lagioia, E. P.; Bono, G. +3 more
We present a theoretical calibration of a new metallicity diagnostic based on the Strömgren index m1 and on visual - near-infrared (NIR) colors to estimate the global metal abundance of cluster and field dwarf stars. To perform the metallicity calibration we adopt α-enhanced evolutionary models transformed into the observational plane b…
Polarimetric coronagraphy of BD + 31°643
Olofsson, G.; Florén, H. -G.; Nilsson, R. +2 more
Context. The binary B5 V star BD + 31°643 exhibits a disk-like structure detected at optical wavelengths. Even though the feature is well centered on the star, it has been argued, based on Spitzer observations, that the feature is a filament not directly associated to the binary star.
Aims: The purpose of the present paper is to investigate w…
Magnetic-topology evolution in NOAA AR 10501 on 2003 November 18
Somov, B. V.; Oreshina, A. V.; Oreshina, I. V.
Context. NOAA AR 10501 produced three flares on 2003 November 18. Two of them were associated with coronal mass ejections (CMEs).
Aims: We model the magnetic-field structure of the active region, study the magnetic-topology evolution, and propose a scenario of the observed events.
Methods: The coronal magnetic field is reconstructed usin…
Deep optical observations of the massive galaxy cluster Abell 1413
Pointecouteau, E.; Benoist, C.; Maurogordato, S. +4 more
Aims: We investigate the morphology and dynamics of the massive nearby galaxy cluster Abell 1413.
Methods: Using wide field imaging and spectroscopic data obtained from observations at the Canada-France-Hawaii Telescope and archival SDSS data, we build a sample of more than 250 galaxies covering a region centered on the cluster and exten…
Retrograde wind accretion - an alternative mechanism for long spin-period of SFXTs
Wang, J.; Chang, H. -K.
A new class of high-mass X-ray binaries (HMXBs) - supergiant fast X-ray transients (SFXTs) - are discovered by INTEGRAL, which are associated with OB supergiants and present long spin periods. Observational evidence indicates that some accreting neutron stars in HMXBs display accretion reversals. It has been suggested that the inverted torque can …