Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userStudying the merging cluster Abell 3266 with eROSITA
99
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The galaxy cluster Abell 3266 is one of the X-ray brightest in the sky and is a well-known merging system. Using the ability of the eROSITA telescope onboard SRG (Spectrum Rontgen Gamma) to observe a wide field with a single pointing, we analyse a new observation of the cluster out to a radius of R_200. The X-ray images highlight substructures present in the cluster, including the northeast-southwest merger seen in previous ASCA, Chandra and XMM-Newton data, a merging group towards the northwest and filamentary structures between the core and one or more groups towards the west. We compute spatially-resolved spectroscopic maps of the thermodynamic properties of the cluster, including the metallicity. The merging subclusters are seen as low entropy material within the cluster. The filamentary structures could be the rims of a powerful AGN outburst, or most likely material stripped from the western group(s) as they passed through the cluster core. Seen in two directions is a pressure jump at a radius of 1.1 Mpc consistent with a shock with a Mach number of ~1.5-1.7. The eROSITA data confirm that the cluster is not a simple merging system, but is made up of several subclusters which are merging or will shortly merge. For the first time we find a radio halo associated with the system detected in GLEAM data. We compute a hydrostatic mass from the eROSITA data, finding good agreement with a previous XMM-Newton result. With this pointing we detect several extended sources, where we find for seven of them secure associations between z=0.36-1.0; i.e., background galaxy groups and clusters, highlighting the power of eROSITA to find such systems.
rate research
Read More
We present results from a BeppoSAX observation of the rich cluster Abell 3266. The broad band spectrum (2-50 keV) of the cluster, when fitted with an optically thin thermal emission model, yields a temperature of 8.1 +/- 0.2 keV and a metal abundance of 0.17 +/- 0.02 in solar units, and with no evidence of a hard X-ray excess in the PDS spectrum. By performing a spatially resolved spectral analysis we find that the projected temperature drops with increasing radius, going from ~ 10 keV at the cluster core to ~ 5 keV at about 1.5 Mpc. Our BeppoSAX temperature profile is in good agreement with the ASCA temperature profile of Markevitch et al. (1998). From our two-dimensional temperature map we find that the gradient is observed in all azimuthal directions. The temperature gradient may have been caused by a recent merger event also responsible for a velocity dispersion gradient measured in the optical band. The projected metal abundance profile and two-dimensional map are both consistent with being constant.
The most nearby clusters are the best places to study physical and enrichment effects in the faint cluster outskirts. A3158 located at z=0.059 is quite extended with a characteristic radius r$_{200}$=23.95 arcmin. In 2019, A3158 was observed as a calibration target in a pointed observation with the eROSITA telescope onboard the SRG mission. We determined 1d temperature, abundance and normalisation profiles from eROSITA and XMM-Newton and Chandra data as well as 2d maps of temperature distribution from eROSITA data. The velocity dispersion was determined and the cluster mass was calculated. The overall temperature was measured to be 4.725$pm$ 0.035 keV. The profiles of eROSITA all agree on a ~10% level with those determined with XMM-Newton and Chandra data. From the temperature map we see that the cluster lacks a cool core, as noted before. The presence of a previously detected off-centre cool clump West of the central cluster region is observed. Furthermore there is a bow shaped edge near the location of the cool gas clump West of the cluster centre. An extension of gas is detected for the first time further out in the West. The velocity dispersion of the cluster was measured to be 1058$pm$41 km s$^{-1}$. The total mass was determined as $M_{200}$=1.38$pm$ 0.25x10$^{15}$ $M_{odot}$. The mass estimate from the M-T relation is significantly lower at M$_{200}$=5.09$pm$ 0.59x10$^{14}M_{odot}$. An extended X-ray source located South of the cluster also coincides with a galaxy overdensity with redshifts in the range 0.05<z<0.07. These are indications that the cluster may be undergoing merger activity. Another extended source located North of the cluster is detected in X-rays and coincides with an overdensity of galaxies with redshifts in the range of 0.070<z<0.077. This is likely a background cluster not related to A3158. Additionally a known SPT cluster at z=0.53 was detected.
We have selected Abell 3266 to search for ram-pressure induced star formation as a global property of a merging cluster. Abell 3266 (z = 0.0594) is a high mass cluster that features a high velocity dispersion, an infalling subcluster near to the line of sight, and a strong shock front. These phenomena should all contribute to making Abell 3266 an optimum cluster to see the global effects of RPS induced star formation. Using archival X-ray observations and published optical data, we cross-correlate optical spectral properties ([OII, H$beta$]), indicative of starburst and post starburst, respectively with ram-pressure, $rho$v$^{2}$, calculated from the X-ray and optical data. We find that post-starburst galaxies, classified as E+A, occur at a higher frequency in this merging cluster than in the Coma cluster and at a comparable rate to intermediate redshift clusters. This is consistent with increased star formation due to the merger. However, both starburst and post-starburst galaxies are equally likely to be in a low or high ram pressure environment. From this result we infer that the duration of the starburst phase must be very brief so that: (1) at any time only a small fraction of the galaxies in a high ram pressure environment show this effect, and (2) most post-starburst galaxies are in an environment of low ram pressure due too their continued orbital motion in the cluster.
The X-ray telescope eROSITA onboard the newly launched SRG mission serendipitously observed the galaxy cluster A3408 ($z=0.0420$) during the PV observation of the AGN 1H0707-495. Despite its brightness and large extent, it has not been observed by any modern X-ray observatory. A neighbouring cluster in NW direction, A3407 ($z=0.0428$), appears to be close at least in projection ($sim 1.7$ Mpc). This cluster pair could be in a pre- or post-merger state. We perform a detailed X-ray analysis of A3408. We construct particle background subtracted and exposure corrected images and surface brightness profiles in different sectors. The spectral analysis is performed out to $1.4r_{500}$. Additionally, a temperature map is presented depicting the distribution of the ICM temperature. Furthermore, we make use of data from the RASS to estimate some bulk properties of A3408 and A3407, using the growth curve analysis method and scaling relations. The imaging analysis shows a complex morphology of A3408 with a strong elongation in 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 compared to the other directions. We determine a gas temperature ${rm k_B}T_{500}=(2.23pm0.09)$ keV. The T-profile reveals a hot core within $2$ of the emission peak, ${rm k_B}T=3.04^{+0.29}_{-0.25}$ keV. Employing a M-T relation, we obtain $M_{500}=(9.27pm0.75)times 10^{13}M_{odot}$ iteratively. The $r_{200}$ of A3407 and A3408 are found to overlap in projection which makes ongoing interactions plausible. The 2d T-map reveals higher temperatures in W than in E direction. A3407 and A3408 are likely in a pre-merger state, affecting the ICM properties, i.e., increased temperatures in the direction of A3407 indicate adiabatic compression or shocks due to the interaction.
Diffuse radio emission has been found in many galaxy clusters, predominantly in massive systems which are in the state of merging. The radio emission can usually be classified as relic or halo emission, which are believed to be related to merger shocks or volume-filling turbulence, respectively. Recent observations have revealed radio bridges for some pairs of very closeby galaxy clusters. The mechanisms that may allow to explain the high specific density of relativistic electrons, necessary to explain the radio luminosity of these bridge regions, are poorly explored. We analyse the galaxy cluster Abell 1430 with LoTSS data in detail and complement it with recent JVLA L-band observations, XMM-Newton, Chandra, and SDSS data. Moreover, we compare our results to clusters extracted from the The Three Hundred Project cosmological simulation. We find that Abell 1430 consists of two components, namely A1430-A and A1430-B. We speculate that the two components undergo an off-axis merger. The more massive component shows diffuse radio emission which can be classified as radio halo showing a low radio power given the mass of the cluster. Most interestingly, there is extended diffuse radio emission, dubbed as the `Pillow, which is apparently related to A1430-B and thus related to low density intracluster or intergalactic medium. To date, a only few examples for emission originating from such regions are known. These discoveries are crucial to constrain possible acceleration mechanisms, which may allow to explain the presence of relativistic electrons in these regions. Our results indicate a spectral index of $alpha_{144,text{MHz}}^{1.5,text{GHz}}=-1.4pm0.5$ for the Pillow. If future observations confirm a slope as flat as the central value of -1.4 or even flatter, this would pose a severe challenge for the electron acceleration scenarios.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
