X-ray Emission and Orientation of Selected PF Galaxy Clusters

TL;DR

This study analyzes the X-ray emission and orientation of 35 galaxy clusters from the PF catalog, focusing on 22 clusters with extended X-ray haloes to compare their X-ray and optical orientations.

Contribution

It provides the first detailed comparison of X-ray and optical orientations for a subset of galaxy clusters, using XMM-Newton data.

Findings

22 clusters have extended elliptic X-ray haloes suitable for orientation analysis.

X-ray and optical orientations show correlation or discrepancy patterns.

Results enhance understanding of cluster morphology and alignment.

Abstract

X-ray counterparts for 35 galaxy clusters contained in the PF catalog of galaxy clusters and groups were found in XMM-Newton archive. 22 ones (all from ACO catalogue) have extended elliptic X-ray haloes appropriate for determination of orientation. Position angles and eccentricities were calculated and compared with cluster orientations optical band.

Tables

Table 1. Table 1: Orientation and eccentricitiesof X-ray PF galaxy clusters.

PF	ACO	PA	$P{A}_X$	$e_{PF}$	$e_X$
0004-3606	2717	160	36$\pm$17	0.29	0.37$\pm$0.08
0009-3469	2721	93	12$\pm$6	0.23	0.67$\pm$0.02
0022-1954	13	102	57$\pm$3	0.13	0.64$\pm$0.04
0034-2570	22	174	105$\pm$7	0.13	0.58$\pm$0.17
0042-3308	S 41	163	118$\pm$1	0.14	0.60$\pm$0.01
0068-2875	2811	119	65$\pm$10	0.24	0.48$\pm$0.05
0082-2951	S 84	6	58$\pm$11	0.17	0.48$\pm$0.06
0104-2195	133	65	16$\pm$6	0.09	0.55$\pm$0.03
0115-4600	2877	179	41$\pm$29	0.17	0.29$\pm$0.09
0168-5458	2933	70	22$\pm$3	0.08	0.75$\pm$0.30
0229-4765	S 239	148	198$\pm$8	0.16	0.59$\pm$0.06
0329-4427	3112	17	12$\pm$1	0.14	0.63$\pm$0.02
0350-5258	3128	162	139$\pm$5	0.14	0.91$\pm$0.05
0370-5364	3158	56	11$\pm$6	0.11	0.50$\pm$0.05
0480-3720	514	61	35$\pm$1	0.20	0.67$\pm$0.01
0500-3868	3301	43	69$\pm$3	0.08	0.48$\pm$0.02
2020-5671	3667	39	31$\pm$5	0.13	0.74$\pm$0.06
2070-3523	3705	122	115$\pm$6	0.29	0.47$\pm$0.04
2149-5088	3771	0	148$\pm$58	0.13	0.62$\pm$0.19
2181-3068	3814	60	16$\pm$4	0.17	0.50$\pm$0.03
2187-1958	2384	167	104$\pm$5	0.29	0.81$\pm$0.05
2229-3570	3854	27	57$\pm$10	0.29	0.41$\pm$0.10

Table 2. Table 2: PF clusters with X-ray sources not suitable for comparison of orientation.

PF	ACO	PA	$P{A}_X$	note
0093-2244	MCXC	131	-	point source
0120-3828	BAX	106	-	point source
0263-5237	3038	146	-	point source
0408-3720	new	180	-	point source
0451-6138	3266	106	-	interacting
0532-2498	Snow 20	24	-	point source
2230-3890	3856	-	50$\pm$4	diff. orient.
2256-3778	3888	-	166$\pm$6
2277-5266	3911	-	50$\pm$4
2323-4265	S 1101	-	147$\pm$1
2331-4225	S 1111	-	-	spherical
2378-2816	4038	-	32$\pm$6
2395-3453	4059	-	58$\pm$5

Table 3. Table 3: Notes on large differences in orientation. Most of such clusters has near-spherical X-ray halo. Optical orientation of last 5 clusters can not be determined because of their diffuse structure.

Name	RA	DEC	PA	e
ACO 2700	0.9567	2.0649	25 $\pm$ 11	0.51 $\pm$ 0.2
ACO 119	14.0675	-1.2489	110 $\pm$ 3	0.09 $\pm$ 0.01
ACO 122	14.3449	-26.281	84 $\pm$ 2	0.713 $\pm$ 0.327
ACO 2984	32.8544	-40.291	84 $\pm$ 1	0.52 $\pm$ 0.4
ACO 399	44.4756	13.0317	63 $\pm$ 15	0.31 $\pm$ 0.1
ACO 401	44.7414	13.5821	53 $\pm$ 1	0.39 $\pm$ 0.25
ACO 3112	49.4902	-44.2385	71 $\pm$ 5	0.62 $\pm$ 0.5
ACO 3158	55.7197	-53.6286	82 $\pm$ 4	0.212 $\pm$ 0.01
ACO S 384	56.4429	-41.204	38 $\pm$ 20	0.36 $\pm$ 0.25
ClG 0422-09	66.4638	-8.5605	19 $\pm$ 1	0.079 $\pm$ 0.01
ACO 496	68.4069	-13.2603	8 $\pm$ 3	0.2 $\pm$ 0.1
ClG 0451-03	73.5469	-3.0146	71 $\pm$ 8	0.17 $\pm$ 0.02
MCXC J0528.9-3927	82.2195	-39.4722	46 $\pm$ 39	0.28 $\pm$ 0.16
MCXC J0532.9-3701	83.2326	-37.0268	88 $\pm$ 1	0.19 $\pm$ 0.14
ACO 3378	91.4753	-35.3023	111 $\pm$ 20	0.45 $\pm$ 0.21
ACO 3391	96.5869	-53.6921	107 $\pm$ 3	0.22 $\pm$ 0.04
ACO 3404	101.371	-54.2267	45 $\pm$ 2	0.47 $\pm$ 0.3
ZwCl 0735+7421	115.435	74.2439	42 $\pm$ 11	0.15 $\pm$ 0.08
ClG 0745-1910	116.881	-19.2952	76 $\pm$ 2	0.17 $\pm$ 0.46
ACO 653	125.46	1.2003	$\pm$	$\pm$
ACO 689	129.353	14.9722	46 $\pm$ 34	0.14 $\pm$ 0.01
ACO 773	139.47	51.7275	103 $\pm$ 5	0.37 $\pm$ 0.25
ACO 901A	149.117	-9.9554	41 $\pm$ 20	0.36 $\pm$ 0.27
ACO 907	149.592	-11.0637	45 $\pm$ 22	0.42 $\pm$ 0.3
ZwCl 1021+0426	155.916	4.1864	35 $\pm$ 9	0.46 $\pm$ 0.4
ACO 1084	161.137	-7.0688	20 $\pm$ 6	0.51 $\pm$ 0.33
ACO 1201	168.228	13.4329	25 $\pm$ 15	0.5 $\pm$ 0.2
ClG J1115+5319	168.811	53.3323	$\pm$	$\pm$
ACO 1413	178.825	23.405	4 $\pm$ 2	0.63 $\pm$ 0.35
MCXC J1206.2-0848	181.552	-8.8018	59 $\pm$ 25	0.24 $\pm$ 0.17
ZwCl 1215+0400	184.42	3.6574	144 $\pm$ 9	0.49 $\pm$ 0.15
ACO S 700	189.172	-33.9246	8 $\pm$ 3	0.07 $\pm$ 0.01
ACO 3528	193.593	-29.013	10 $\pm$ 1	0.6 $\pm$ 0.4
ACO 1651	194.844	-4.1954	99 $\pm$ 3	0.35 $\pm$ 0.27
ACO 1656	194.944	27.9699	73 $\pm$ 3	0.18 $\pm$ 0.1
ACO 1663	195.718	-2.5148	48 $\pm$ 39	0.3 $\pm$ 0.2
ACO 1664	195.927	-24.2452	157 $\pm$ 5	0.48 $\pm$ 0.25
2E 2975	197.329	-1.6224	60 $\pm$ 15	0.28 $\pm$ 0.25
1RXS J132441.9-573650	201.195	-57.6103	45 $\pm$ 33	0.17 $\pm$ 0.1
ACO 3558	201.985	-31.495	43 $\pm$ 16	0.47 $\pm$ 0.3
ACO 1750N	202.795	-1.7292	140 $\pm$ 25	0.379 $\pm$ 0.24
ACO 3560	203.112	-33.1415	26 $\pm$ 14	0.32 $\pm$ 0.27
ACO 3562	203.397	-31.6744	150 $\pm$ 29	0.31 $\pm$ 0.14
ACO 1775	205.456	26.3719	136 $\pm$ 40	0.31 $\pm$ 0.23
ACO 3571	206.869	-32.8622	84 $\pm$ 2	0.3 $\pm$ 0.01
ClG J1347-1145	206.879	-11.7532	11 $\pm$ 6	0.15 $\pm$ 0.08
ACO 1835	210.258	2.8783	10 $\pm$ 5	0.21 $\pm$ 0.16
ACO 3581	211.871	-27.0173	69 $\pm$ 7	0.2 $\pm$ 0.06
2XMM J141830.6+251052	214.628	25.1812	30 $\pm$ 3	0.45 $\pm$ 0.3
NGC 5718 Group	220.175	3.4679	61 $\pm$ 2	0.22 $\pm$ 0.15
ClG J1504-0248	226.032	-2.8046	147 $\pm$ 17	0.1 $\pm$ 0.06
ACO 2050	229.076	0.0919	141 $\pm$ 34	0.47 $\pm$ 0.25
ACO 2052	229.172	7.0026	135 $\pm$ 6	0.48 $\pm$ 0.3
ACO 2051	229.185	-0.9698	64 $\pm$ 8	$\pm$
ACO 2055	229.691	6.2322	12 $\pm$ 12	0.31 $\pm$ 0.13
ACO 2063	230.77	8.6079	8 $\pm$ 4	0.25 $\pm$ 0.06
ACO 2204	248.196	5.5755	7 $\pm$ 5	0.087 $\pm$ 0.01
ClG J1720+2638	260.042	26.6252	70 $\pm$ 3	0.38 $\pm$ 0.01
MCXC J2011.3-5725	302.863	-57.4193	60 $\pm$ 15	0.28 $\pm$ 0.25
ACO 3667	303.112	-56.8345	8 $\pm$ 8	0.76 $\pm$ 0.08
2MAXI J2014-244	303.715	-24.5059	9 $\pm$ 1	0.52 $\pm$ 0.45
ACO 3693	308.583	-34.4935	39 $\pm$ 23	0.12 $\pm$ 0.08
ClG J2129+0005	322.416	0.0891	24 $\pm$ 1	0.5 $\pm$ 0.3
ACO 3814	327.281	-30.7011	65 $\pm$ 23	0.56 $\pm$ 0.27
XMMXCS J221656.6-172527.2	334.236	-17.4235	71 $\pm$ 6	0.22 $\pm$ 0.2
ACO 3854	334.441	-35.7253	37 $\pm$ 22	0.51 $\pm$ 0.37
ACO 3856	334.667	-38.9008	39 $\pm$ 10	0.56 $\pm$ 0.31
ACO S 1101	348.494	-42.7272	121 $\pm$ 2	0.45 $\pm$ 0.3
ACO 3992	349.919	-73.2259	2 $\pm$ 2	0.37 $\pm$ 0.1
ACO 2597	351.332	-12.1243	37 $\pm$ 1	0.17 $\pm$ 0.05
ACO 4010	352.807	-36.5111	148 $\pm$ 4	0.148 $\pm$ 0.01
ACO 2626	354.127	21.1462	156 $\pm$ 5	0.67 $\pm$ 0.06
ACO 2667	357.914	-26.0841	133 $\pm$ 27	0.403 $\pm$ 0.28
ACO 2670	358.562	-10.4172	132 $\pm$ 35	0.23 $\pm$ 0.14
ACO 13	3.4044	-19.4976	60 $\pm$ 20	0.41 $\pm$ 0.1
2XMMi J001737.3-005239	4.4058	-0.8777	149 $\pm$ 2	$\pm$
ClG 0016+16	4.6394	16.4368	$\pm$	$\pm$

Full text

X-RAY EMISSION AND ORIENTATION

OF SELECTED PF GALAXY CLUSTERS

A.V. Tugay1, S.S. Dylda1, E.A. Panko2

1 Astronomy and Space Physics Department, Faculty of Physics,

Taras Shevchenko National University of Kyiv,

Glushkova ave., 4, Kyiv, 03127, Ukraine, tugay.anatoliy@gmail.com

2 Department of Theoretical Physics and Astronomy,

I.I. I. I. Mechnikov Odessa National University,

Shevchenko Park, Odessa, 65014, Ukraine, panko.elena@gmail.com

ABSTRACT. X-ray counterparts for 35 galaxy clusters contained in the PF catalog of galaxy clusters and groups were found in XMM-Newton archive. 22 ones (all from ACO catalogue) have extended elliptic X-ray haloes appropriate for determination of orientation. Position angles and eccentricities were calculated and compared with cluster orientations optical band.

Keywords: Galaxies: clusters; X-rays: galaxies: clusters.

**1. Introduction

**

The study of morphology of galaxy clusters is important for understanding the large scale structure of Universe. Orientation of galaxies and clusters may give information about clusterisation and cosmologic evolution. The best way to consider orientation of extragalactic objects is the usage of special large and uniform catalog of galaxy clusters. Clusters are also suitable for orientation analysis in X-ray band because they contain a haloes of hot intergalactic gas.

Since (Binggeli, 1984) orientation of galaxies in clusters was the subject of numerous studies. Orientations of galaxies in 247 rich Abell clusters were studied in detail in Godlowski et al. (2010) and Panko et al. (2013) with corresponding statistical analysis and simulations. Orientation of galaxies from compact sample can be numerically described by the distribution of anisotropy parameter. The parameter was calculated for edge-on galaxies in Parnovsky & Tugay (2007) and for nearby galaxy groups in Godlowski et al.(2012). Orientation of galaxies in nearby groups was studied by Pajowska et al.(2012) too.

**2. Observational data

**

Our study in optic band based on PF catalogue of galaxy clusters and groups data. The catalogue contains 6188 structures of southern sky (Panko & Flin, 2006). Orientations and shapes of PF clusters were calculated taking into consideration galaxy $2D$ locations in the cluster field using the covariance ellipse method (Carter & Metcalfe, 1980; Biernacka et al., 2007). To select PF clusters counterparts in X-rays we used Xgal list of all X-ray extragalactic sources observed by XMM-Newton space observatory (Tugay, 2012). Xgal includes 5021 sources and approximately 30% of them are galaxy clusters. In the current study we found PF clusters counterparts in X-rays, calculated their orientations and eccentricities in X-ray band and compared obtained values with optical data.

**3. Method

**

Cross-correlation of PF and Xgal objects was performed on the base of condition of appearing Xgal source within PF cluster radius. We found 35 Xgal sources counterparts in PF catalogue. To estimate orientation of X-ray halo we selected at XMM images pixels with certain numbers of detected photons (two, three, four etc). Then we approximated each set of pixels with ellipse by the minimal square method and found positional angle PA and eccentricity e. We succeeded to find X-ray orientation for 28 Abell clusters (Abell, Corwin & Olowin, 1989) from PF catalog but 6 of them have no appropriate optical orientation. Common results are presented in Table 1. Table 2 shows PF clusters with X-ray sources that are unappropriate for orientation determination by any reason.

**3. The general notes on selected clusters

**

Here are general notes on selected clusters.

A 2717, A 2877, A S 1111. These clusters looks like spherical, but for first and second ones we determined PA.

A 13, A 2811, AO S 84, A S 239, AO 3158, A 3667, A 3771, A 3856. Orientation of cluster core differs from periphery. We didn’t determine PA for A 3856.

Double clusters: A 2933, A 3128, A 2384.

Faint clusters: A S 41, A 514, A 3301.

A 3705 - a pair of interacting clusters, but PA was found by X-ray image.

Clusters with undefined orientation or with large differences in optical and X-ray PA are presented in Table 3.

Except for 22 clusters with both optical and X-ray orientation there are 13 PF clusters with X-ray sources for which it is impossible to compare orientations.

4 point X-ray sources were found within PF clusters. No X-ray haloes of galaxy clusters were detected for these systems.

1. PF 0120-3828. BAX 017.9025-38.1867 cluster. X-ray source 2MASXJ00570192-3806028 galaxy (only 3 references in SIMBAD).

2. PF 0093-2244. MCXC J0056.9-2213 cluster. X-ray source RBS139 Seyfert 1 galaxy.

3. PF 0263-5237. Abell 3038 cluster. X-ray source ESO 198-24 Seyfert 1 galaxy.

4. PF 0532-2498. Snow 20 cluster (T.Snow, 1970). X-ray source - IC 411 galaxy (9 references).

PF 0408-3720 cluster was unknown in previous works. In the region of this cluster we found ESO 359-19 Seyfert 1 galaxy.

A 3266 - complex system of interacting clusters unappropriate for orientation estimation in X-rays.

Seven PF clusters (bottom of Table 2) does not show anisotropy in optical band, so we excluded them from comparison with X-ray data. Specifically, A 3856 shows different orientation of the core and periphery of X-ray halo; A 1111 has spherical halo; other clusters include A 1101, A 3888, A 3911, A 4038 and A 4059.

**4. Results and conclution

**

Analysis of Table 1 shows that PA tend to correlate. Eccentricity is larger in X-rays because visible hot gas halo lies close to the center of cluster in the region of larger potential. The correlation of orientation in two bands leads to issue that galaxies and gas halo in clusters are involved in significant gravitational interaction but the processes of cluster evolution continue in the current cosmological era.

Acknowledgements. This research has made use of NASA’s Astrophysics Data System.

**References

**

Abell G.O., Corwin H.G., Olowin, R.P.: 1989, ApJS, 70, 1.

Biernacka M., Flin P., Panko E., Juszczyk T.: 2007, Odessa Astron. Publ., 20, 26.

Binggeli B.: 1984, A& A, 107, 338

Carter D., Metcalf, N.: 1980 MNRAS, 191, 325. Godlowski W., Piwowarska P., Panko E., Flin P.: 2010, ApJ, 723, 985.

Godlowski M., Panko E., Pajowska P., Flin P.: 2012, JPhSt., 16, 3901.

Pajowska P., Godlowski M., Panko E., Flin P.: 2012, JPhSt., 16, 4901.

Panko E., Flin P.: 2006, JAD., 12, 1.

Panko E., Piwowarska P., Godlowska J., Godlowski W., Flin P.: 2013, Ap., 56, 322.

Parnovsky S., Tugay A.: 2007, JPhSt., 11, 366.

Tugay A.V.: 2012, Odessa Astron. Publ., 25, 142.

    http://arxiv.org/abs/1311.4333