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A Giant Sloshing Cold Front in Abell 2142 (+Bonus)

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A Giant Sloshing Cold Front in Abell 2142 (+Bonus) A giant sloshing cold front in Abell 2142 (+Bonus) Dominique Eckert Department of Astronomy, University of Geneva Collaborators: Mariachiara Rossetti, Sabrina De Grandi, Fabio Gastaldello, Simona Ghizzardi, Elke Roediger, Silvano Molendi, Larry Rudnick, Damon Farnsworth D. Eckert January 15, 2013 The case of Abell 2142 A2142 (z=0.09): first cluster where CFs have been observed (Markevitch et al. 2000) Markevitch & Vikhlinin 2007 D. Eckert January 15, 2013 Tittley & Henriksen (2005) classify the CFs in A2142 as sloshing ! Owers et al. 2011 ... However this interpretation is hard to reconcile with the galaxy velocity distribution The riddle of the dynamical state In the discovery paper M00 interpreted A2142 as a merging cluster and the CFs as remnant cores D. Eckert January 15, 2013 Tittley & Henriksen (2005) classify the CFs in A2142 as sloshing ! MINOR MERGERS IN A2142 AND RXJ1720 9 The riddle of the dynamical state Figure 4. Phase space diagrams used for defining cluster membership forA2142(left panel)andRXJ1720(right panel). The red curves show the cluster limits in phase-space and are determined from the cluster mass profile (see the text for a description). Black crosses In the discoveryshow paper cluster membersM00 interpreted which lie on the red A2142 sequence, as while a mergingbluestarswithinthephasespacelimitsshowthoseclustermemb cluster ers which lie blueward of the red sequence. Red boxes show fore- and background galaxies. Red boxes filled with blue stars show non-members which and the CFs asare remnant bluer than the cores cluster red sequence. Owers et al. 2011 ... However this interpretation is hard to reconcile with the galaxy velocity distribution D. Eckert January 15, 2013 Figure 5. The velocity distribution for all 956 cluster members (top left panel), 463 members with 1500 <Rproj< 3000 kpc (top right), 270 members with 750 <Rproj< 1500 kpc (bottom left)and223memberswithRproj< 750 kpc (bottom right). In each panel, the best fitting Gaussian parameters, the Gauss-Hermite terms h3 and h4,representingtheasymmetricandsymmetricdeviationsfromaGaussian shape, and their associated level of significance (see text) are given in the upper right corner. The histograms show the observed velocity (1./3.) distribution and the bin size is set to 3S/(Ngal) ,whereNgal is the number of galaxies listed above. The solid black line shows the best fitting Gaussian, while the dashed red line shows the Gauss-Hermite reconstriction of the velocity distribution. The riddle of the dynamical state In the discovery paper M00 interpreted A2142 as a merging cluster and the CFs as remnant cores MINORMERGERSINA2142ANDRXJ1720 17 Owers et al. 2011 ... However this interpretation is hard to reconcile with the galaxy velocity distribution Tittley & Henriksen (2005) classify the CFs in A2142 as sloshing ! D. Eckert January 15, 2013 Figure 12. Top panel: The black circles show regions selected for the KMManalysesbasedonsubstructurerevealedinFigure7and 10. Black contours show galaxy surface density as in Figure 7.Thestarsarecolorcodedtomatchthecorrespondingvelocity components shown in the lower panels. Black points reveal the positions of the remaining cluster members. The riddle of the dynamical state Unlike all known sloshing clusters, A2142 is not a cool core 2 (K0 = 68 keV cm ) Ghizzardi et al. 2010 D. Eckert January 15, 2013 Sloshing ! Concentric edges as in simulations ! Optical subcluster identified as candidate perturber (Matt’s talk) % Not a relaxed, cool core cluster, flat entropy profile % Hosts a giant radio halo like major merger clusters (Damon’s talk) The origin of the CFs is still uncertain! We obtained a new 50 ks XMM observation to constrain the dynamics! The riddle of the dynamical state Pros and cons Remnant core ! Cometary shape of the edges ! Overall elongation in X-rays and in the optical in the SE-NW direction ! Not a relaxed, cool core cluster % Problem with the optical distribution: where are the galaxies associated to the NW CF? D. Eckert January 15, 2013 The origin of the CFs is still uncertain! We obtained a new 50 ks XMM observation to constrain the dynamics! The riddle of the dynamical state Pros and cons Remnant core Sloshing ! Cometary shape of the edges ! Concentric edges as in ! Overall elongation in X-rays simulations and in the optical in the ! Optical subcluster identified SE-NW direction as candidate perturber ! Not a relaxed, cool core (Matt’s talk) cluster % Not a relaxed, cool core % Problem with the optical cluster, flat entropy profile distribution: where are the % Hosts a giant radio halo like galaxies associated to the major merger clusters NW CF? (Damon’s talk) D. Eckert January 15, 2013 The riddle of the dynamical state Pros and cons Remnant core Sloshing ! Cometary shape of the edges ! Concentric edges as in ! Overall elongation in X-rays simulations and in the optical in the ! Optical subcluster identified SE-NW direction as candidate perturber ! Not a relaxed, cool core (Matt’s talk) cluster % Not a relaxed, cool core % Problem with the optical cluster, flat entropy profile distribution: where are the % Hosts a giant radio halo like galaxies associated to the major merger clusters NW CF? (Damon’s talk) The origin of the CFs is still uncertain! We obtained a new 50 ks XMM observation to constrain the dynamics! D. Eckert January 15, 2013 Abell 2142 as seen by XMM A2142 was observed by XMM for 50 ks on July 13, 2011 D. Eckert January 15, 2013 We discovered a third discontinuity 1 Mpc SE of the cluster core ∼ Abell 2142 as seen by XMM The two inner CFs are clearly visible D. Eckert January 15, 2013 Abell 2142 as seen by XMM The two inner CFs are clearly visible We discovered a third discontinuity 1 Mpc SE of the cluster core ∼ D. Eckert January 15, 2013 SB profiles in NW and SE directions SB discontinuity detected 10 arcmin from the∼ cluster center A2142 ROSAT/PSPC data The third discontinuity was not unexpected to us Clearly visible in the ROSAT residual image D. Eckert January 15, 2013 SB discontinuity detected 10 arcmin from the∼ cluster center A2142 ROSAT/PSPC data The third discontinuity was not unexpected to us Clearly visible in the ROSAT residual image SB profiles in NW and SE directions D. Eckert January 15, 2013 A2142 ROSAT/PSPC data The third NW sector SE sector discontinuity was not NW CF SE CF unexpected to us 10-1 ] Clearly visible in the -2 ROSAT residual 10-2 image arcmin -1 SB profiles in NW 10-3 and SE directions SB discontinuity SB [counts s 10-4 detected 10 arcmin ∼ from the cluster 1 10 center Distance [arcmin] Rossetti et al. subm. D. Eckert January 15, 2013 Third discontinuity: XMM/PN SB profile SE sector -1 ] 10 -2 arcmin -1 SB [counts s 10-2 10 Radius [arcmin] Rossetti et al. subm. Density jump: nin=nout = 1:79 0:06 Distance to the center: 947 3± kpc Linear size of the discontinuity:± 1.2 Mpc D. Eckert January 15, 2013 The shock hypothesis is excluded at > 5s The third discontinuity is the largest and outermost cold front ever detected Third discontinuity: temperature jump +0:45 +2:4 kTin = 6:13 0:37 keV kTout = 9:0 1:5 keV − − Source Source NXB NXB Halo CXB CXB QSP QSP Halo Local Local Bubble Bubble Rossetti et al. subm. D. Eckert January 15, 2013 Third discontinuity: temperature jump +0:45 +2:4 kTin = 6:13 0:37 keV kTout = 9:0 1:5 keV − − Source Source NXB NXB Halo CXB CXB QSP QSP Halo Local Local Bubble Bubble Rossetti et al. subm. The shock hypothesis is excluded at > 5s The third discontinuity is the largest and outermost cold front ever detected D. Eckert January 15, 2013 The CF is asymmetric, more extended toward the NE than toward the SW This is unlike the case of the remnant core in A3667 (Vikhlinin et al. 2001) Rossetti et al. subm. Rossetti M. et al.: Abell 2142 at large scales: An extreme case for sloshing? Source Source "'"! "'! "'"! "'! ! ! ! ! NXB 2708 2708 ! ! ! NXB ! & & ! ! !" !" Halo CXB CXB QSP % QSP % ! ! Halo !" !" ()*+,-./0123)4(5626 ()*+,-./0123)4(5626 Local Local Bubble Bubble $ $ ! ! !" ! #$!" !" ! #$!" 9(0*:;2<708= 9(0*:;2<708= Figure 3: XMM-Newton/MOS spectra of theStability IN (left) and OUT of (right) the regions NW and CF best-fit models. MOS1 data are shown in black, MOS2 in red. The contribution from the various background components (sky: local bubble, Galactic halo and CXB; internal: NXB and QSP) is compared to the best-fit source model.We studied the stability of the NW CF by measuring the SB jump in several sectors 27.250 27.200 27.150 IN Declination OUT 27.100 27.050 239.850 239.800 239.750 239.700 239.650 239.600 Right ascension Figure 4: Zoom on the SE (left) and NW (right) cold fronts, with the regions used for spectral and imaging analysis. details of the background modeling are described in Appendix. Hugoniot conditions predict an outer temperature of 3.9 keV. Spectral fitting to the spectra in the IN and OUT regions was per- Fixing the temperatureD. Eckert of the plasmaJanuary to 3.9 15, keV, 2013 we find a di↵er- formed using XSPEC v12.7.0 and the modified C-statistic. The ence in C-statistic ∆C = 28.1 with respect to the best-fit temper- appropriate e↵ective area was applied to the sky components, ature of 9.0 keV, which translates into a rejection of this hypoth- but not to the NXB and QSP components. The source spectrum esis at a confidence level of 5.3σ. Therefore, we can conclude was modeled with an absorbed APEC model with metal abun- with good confidence that this discontinuity is a cold front. At dance fixed to 0.3Z and redshift fixed to that of the cluster.
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