Constraints on turbulent pressure in the X-ray halos of giant elliptical galaxies from resonant scattering

Abstract

Abstract. The dense cores of X-ray emitting gaseous halos of large elliptical galaxies with temperatures below about 0.8 keV show two prominent Fe XVII emission features, which provide a sensitive diagnostic tool to measure the effects of resonant scattering. We present here highresolution spectra of five bright nearby elliptical galaxies, obtained with the Reflection Grating Spectrometers (RGS) on the XMM-Newton satellite. The spectra for the cores of four of the galaxies show the Fe XVII line at 15.01 Angstrom being suppressed by resonant scattering. The data for NGC 4636 in particular allow the effects of resonant scattering to be studied in detail. Using deprojected density and temperature profiles for this galaxy obtained with the Chandra satellite, we model the radial intensity profiles of the strongest resonance lines, accounting for the effects of resonant scattering, for different values of the characteristic turbulent velocity. Comparing the model to the data, we find that the isotropic turbulent velocities on spatial scales smaller than about 1 kpc are less than 100 km/s and the turbulent pressure support in the galaxy core is smaller than 5% of the thermal pressure at the 90% confidence level, and less than 20% at 99% confidence. Neglecting the effects of resonant scattering in spectral fitting of the inner 2 kpc core of NGC 4636 will lead to underestimates of the chemical abundances of Fe and O by about 10-20%. 297at https://www.cambridge.org/core/terms. https://doi

X-ray spectroscopy of galaxy clusters: studying astrophysical processes in the largest celestial laboratories

“…Following up the work by Xu et al (2002);Werner et al (2009) analyzed the XMM-Newton RGS data of five nearby bright elliptical galaxies and found that the Fe xvii lines in the cores of four galaxies show evidence for resonance scattering in the innermost region. The data for NGC 4636 in particular allowed the effects of resonant scattering to be studied in detail.…”

“…The data for NGC 4636 in particular allowed the effects of resonant scattering to be studied in detail. Werner et al (2009) used deprojected density and temperature profiles obtained by Chandra to model the radial intensity profiles of the strongest resonance lines, accounting for the effects of resonant scattering, for different values of the characteristic turbulent velocity. Comparing the model to the Fig.…”

“…In order to determine the amount of resonant scattering Werner et al (2009) studied the line ratios of the Fe xvii ion in 5 elliptical galaxies (see Sect. 3.5).…”