X-ray study of the merging galaxy cluster Abell 3411-3412 with XMM-Newton and Suzaku

Abstract

Context. Previous Chandra observations of the Abell 3411-3412 merging galaxy cluster system revealed an outbound bullet-like sub-cluster in the northern part and many surface brightness edges at the southern periphery, where multiple diffuse sources are also reported from radio observations. Notably, a southeastern radio relic associated with fossil plasma from a radio galaxy and with a detected X-ray edge provides direct evidence of shock re-acceleration. The properties of the reported surface brightness features have yet to be constrained from a thermodynamic viewpoint. Aims. We use the XMM-Newton and Suzaku observations of Abell 3411-3412 to reveal the thermodynamical nature of the previously reported re-acceleration site and other X-ray surface brightness edges. We also aim to investigate the temperature profile in the low-density outskirts with Suzaku data. Methods. We performed both imaging and spectral analysis to measure the density jump and the temperature jump across multiple known X-ray surface brightness discontinuities. We present a new method to calibrate the vignetting function and spectral model of the XMM-Newton soft proton background. Archival Chandra, Suzaku, and ROSAT data are used to estimate the cosmic X-ray background and Galactic foreground levels with improved accuracy compared to standard blank sky spectra. Results. At the southeastern edge, temperature jumps revealed by both XMM-Newton and Suzaku point to a ℳ ∼ 1.2 shock, which agrees with the previous result from surface brightness fits with Chandra. The low Mach number supports the re-acceleration scenario at this shock front. The southern edge shows a more complex scenario, where a shock and the presence of stripped cold material may coincide. There is no evidence for a bow shock in front of the northwestern “bullet” sub-cluster. The Suzaku temperature profiles in the southern low-density regions are marginally higher than the typical relaxed cluster temperature profile. The measured value kT500 = 4.84 ± 0.04 ± 0.19 keV with XMM-Newton and kT500 = 5.17 ± 0.07 ± 0.13 keV with Suzaku are significantly lower than previously inferred from Chandra.

The Coma Cluster at LOFAR Frequencies. II. The Halo, Relic, and a New Accretion Relic

“…For MOS, the scale factor was calculated using the ratio of out-of-field-of-view (OoFoV) count rates. For pn, even the OoFoV area can be contaminated by soft protons, and it cannot be used for an accurate rescaling of the NXB (Gastaldello et al 2017;Zhang et al 2020;Marelli et al 2021). On the other hand, the pn instrumental background shows a similar long-term variability to that of Chandraʼs ACIS-S3 chip; therefore, we used this information for rescaling the pn NXB level in the observations (details are provided in Zhang et al, in preparation).…”

The Coma cluster at LOFAR frequencies II: the halo, relic, and a new accretion relic

“…For MOS, the scale factor was calculated using the ratio of out-of-field-of-view (OoFoV) count rates. For pn, even the OoFoV area can be con-2 http://xmm-tools.cosmos.esa.int/external/xmm user support/documentation/sas usg/USG/removingOoTimg.html taminated by soft protons, and cannot be used for an accurate rescaling of the NXB (Gastaldello et al 2017;Zhang et al 2020;Marelli et al 2021). On the other hand, the pn instrumental background shows a similar long term variability as that of Chandra's ACIS-S3 chip; therefore we used this information for rescaling the pn NXB level in the observations (details are provided in Zhang et al in prep).…”

Deep Chandra observations of merging galaxy cluster ZwCl 2341+0000

“…Using Eqs. C.4 and C.5 in Zhang et al (2020) and assuming the log N − log S relation is identical to the Chandra Deep Field South (Lehmer et al 2012), the corresponding point source exclusion limit is 3 × 10 −15 erg s −1 cm −2 and the CXB residual uncertainty on a 1 arcmin 2 area is 57%. For any of the spectra in the analysis, the CXB residual uncertainty is scaled from 57% by a factor of A −1/2 , where A is the extraction area converted from the backscal value in the spectrum header.…”