Studying the merging cluster Abell 3266 with eROSITA

Sanders, J. S.; Biffi, V.; Brüggen, M.; Bülbül, Esra; Dennerl, K.; Dolag, K.; Erben, T.; Freyberg, M. J.; Gatuzz, E.; Ghirardini, Vittorio; Hoang, D. N.; Klein, Matthias; Liu, Ang; Merloni, A.; Pacaud, F.; Ramos-Ceja, M. E.; Reiprich, T. H.; ZuHone, John

doi:10.1051/0004-6361/202141501

Cited by 27 publications

(15 citation statements)

References 64 publications

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“…However, this difference is small, namely of 10-15% in the full 0.7−7 keV band for low-temperature clusters (<4 keV) to which we are sensitive in the eFEDS observations. Our preliminary calibration studies with eROSITA showed that, in general, eROSITA temperatures are in good agreement with Chandra and XMM-Newton temperatures (Sanders et al 2022;Veronica et al 2022;Iljenkarevic et al 2022;Whelan et al 2021). Turner et al (2021) recently cross-matched the eFEDS cluster catalog (Liu et al 2022a) with the XMM-Newton Cluster Survey (XCS, Romer et al 2001) sample and found luminosities of 29 cross-matched clusters to be in excellent agreement.…”

Section: Resultssupporting

confidence: 62%

The eROSITA Final Equatorial-Depth Survey (eFEDS)

Bahar

Bülbül

Clerc

et al. 2022

A&A

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Context. Scaling relations link the physical properties of clusters at cosmic scales. They are used to probe the evolution of large-scale structure, estimate observables of clusters, and constrain cosmological parameters through cluster counts. Aims. We investigate the scaling relations between X-ray observables of the clusters detected in the eFEDS field using Spectrum-Roentgen-Gamma/eROSITA observations taking into account the selection effects and the distributions of observables with cosmic time. Methods. We extract X-ray observables (LX, Lbol, T, Mgas, YX) within R500 for the sample of 542 clusters in the eFEDS field. By applying detection and extent likelihood cuts, we construct a subsample of 265 clusters with a contamination level of <10% (including AGNs and spurious fluctuations) to be used in our scaling relations analysis. The selection function based on the state-of-the-art simulations of the eROSITA sky is fully accounted for in our work. Results. We provide the X-ray observables in the core-included <R500 and core-excised 0.15 R500-R500 apertures for 542 galaxy clusters and groups detected in the eFEDS field. Additionally, we present our best-fit results for the normalization, slope, redshift evolution, and intrinsic scatter parameters of the X-ray scaling relations between LX - T, LX - Mgas, LX - YX, Lbol - T, Lbol - Mgas, Lbol - YX, and Mgas - T. We find that the best-fit slopes significantly deviate from the self-similar model at a >4σ confidence level, but our results are nevertheless in good agreement with the simulations including non-gravitational physics, and the recent results that take into account selection effects. Conclusions. The strong deviations we find from the self-similar scenario indicate that the non-gravitational effects play an important role in shaping the observed physical state of clusters. This work extends the scaling relations to the low-mass, low-luminosity galaxy cluster and group regime using eFEDS observations, demonstrating the ability of eROSITA to measure emission from the intracluster medium out to R500 with survey-depth exposures and constrain the scaling relations in a wide mass-luminosity-redshift range.

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Section: Resultssupporting

confidence: 62%

The eROSITA Final Equatorial-Depth Survey (eFEDS)

Bahar

Bülbül

Clerc

et al. 2022

A&A

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“…Furthermore, if an emission bridge does connect the two clusters, the eRASS image will provide its observation. More generally, given the early eROSITA results on cluster outskirts and infall regions (e.g., Reiprich et al 2021;Ghirardini et al 2021;Churazov et al 2021;Veronica et al 2022;Whelan et al 2021;Sanders et al 2022), and given the close correspondence to similar structures observed in cosmological hydrodynamical simulations (e.g., Biffi et al 2022), we may expect that bridges and clumpy filaments will be discovered in several more nearby systems in the future in the eRASS. These systems can then be studied in detail after the eight surveys are completed using the SRG/eROSITA scanning mode, with which areas of tens of square degrees can be scanned efficiently, homogeneously, and deeply.…”

Section: Discussionmentioning

confidence: 73%

eROSITA spectro-imaging analysis of the Abell 3408 galaxy cluster

Iljenkarevic

Reiprich

Pacaud

et al. 2022

A&A

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Context. The X-ray telescope eROSITA on board the newly launched Spectrum-Roentgen-Gamma (SRG) mission serendipitously observed the galaxy cluster Abell 3408 (A3408) during the performance verification observation of the active galactic nucleus 1H 0707–495. The field of view of eROSITA is one degree, which allowed us to trace the intriguing elongated morphology of the nearby (z = 0.0420) A3408 cluster. Despite its brightness (F500 ≈ 7 × 10−12 ergs s−1 cm−2) and large extent (r200 ≈ 21'), it has not been observed by any modern X-ray observatory in over 20 yr. A neighboring cluster in the NW direction, A3407 (r200 ≈ 18', z = 0.0428), appears to be close at least in projection (~1.7 Mpc). This cluster pair might be in a pre- or post-merger state. Aims. We aim to determine the detailed thermodynamical properties of this special cluster system for the first time. Furthermore, we aim to determine which of the previously suggested merger scenarios (pre- or post-merger) is preferred. Methods. We performed a detailed X-ray spectro-imaging analysis of A3408. We constructed particle-background-subtracted and exposure-corrected images and surface brightness profiles in different sectors. The spectral analysis was performed out to 1.4r500 and included normalization, temperature, and metallicity profiles determined from elliptical annuli aligned with the elongation of A3408. Additionally, a temperature map is presented that depicts the distribution of the intracluster medium (ICM) temperature. Furthermore, we make use of data from the ROSAT all-sky survey to estimate some bulk properties of A3408 and A3407, using the growth-curve analysis method and scaling relations. Results. The imaging analysis shows the complex morphology of A3408 with a strong elongation in the SE-NW direction. This is quantified by comparing the surface brightness profiles of the NW, SW, SE, and NE directions, where the NW and SE directions show a significantly higher surface brightness than the other directions. We determine a gas temperature kBr500 = (2.23 ± 0.09) keV in the range 0.2r500 to 0.5r500 from the spectral analysis. The temperature profile reveals a hot core within two arcminutes of the emission peak, ${k_{\rm{B}}}T = 3.04_{- 0.25}^{+ 0.29}$ keV. Employing a mass–temperature relation, we obtain M500 = (9.27 ± 0.75) × 1013M⊙ iteratively. The r200 of A3407 and A3408 are found to overlap in projection, which makes ongoing interactions plausible. The two-dimensional temperature map reveals higher temperatures in the W than in the E direction. Conclusions. The elliptical morphology together with the temperature distribution suggests that A3408 is an unrelaxed system. The system A3407 and A3408 is likely in a pre-merger state, with some interactions already affecting the ICM thermodynamical properties. In particular, increased temperatures in the direction of A3407 indicate adiabatic compression or shocks due to the starting interaction.

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“…Abell 3266 has been extensively observed at X-ray wavelengths (Markevitch et al 1998;Mohr et al 1999;De Grandi & Molendi 1999;Henriksen et al 2000;Sauvageot et al 2005;Finoguenov et al 2006;Sanders et al 2022). All observational results show that Abell 3266 is undergoing a complex merger event, presenting an elongated and asymmetric X-ray surface brightness distribution, as well as an asymmetric temperature profile.…”

Section: Abell 3266mentioning

confidence: 93%

Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA

Riseley

Bonnassieux

Vernstrom

et al. 2022

Monthly Notices of the Royal Astronomical Society

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Abell 3266 is a massive and complex merging galaxy cluster that exhibits significant substructure. We present new, highly sensitive radio continuum observations of Abell 3266 performed with the Australian Square Kilometre Array Pathfinder (0.8–1.1 GHz) and the Australia Telescope Compact Array (1.1–3.1 GHz). These deep observations provide new insights into recently reported diffuse non-thermal phenomena associated with the intracluster medium, including a ‘wrong-way’ relic, a fossil plasma source, and an as-yet unclassified central diffuse ridge, which we reveal comprises the brightest part of a large-scale radio halo detected here for the first time. The ‘wrong-way’ relic is highly atypical of its kind: it exhibits many classical signatures of a shock-related radio relic, while at the same time exhibiting strong spectral steepening. While radio relics are generally consistent with a quasi-stationary shock scenario, the ‘wrong-way’ relic is not. We study the spectral properties of the fossil plasma source; it exhibits an ultrasteep and highly curved radio spectrum, indicating an extremely aged electron population. The larger scale radio halo fills much of the cluster centre, and presents a strong connection between the thermal and non-thermal components of the intracluster medium, along with evidence of substructure. Whether the central diffuse ridge is simply a brighter component of the halo, or a mini-halo, remains an open question. Finally, we study the morphological and spectral properties of the multiple complex radio galaxies in this cluster in unprecedented detail, tracing their evolutionary history.

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Studying the merging cluster Abell 3266 with eROSITA

Cited by 27 publications

References 64 publications

The eROSITA Final Equatorial-Depth Survey (eFEDS)

The eROSITA Final Equatorial-Depth Survey (eFEDS)

eROSITA spectro-imaging analysis of the Abell 3408 galaxy cluster

Radio fossils, relics, and haloes in Abell 3266: cluster archaeology with ASKAP-EMU and the ATCA

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