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Structure and Kinematics of the Virgo Cluster of Galaxies? Olga G

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Structure and Kinematics of the Virgo Cluster of Galaxies? Olga G A&A 635, A135 (2020) Astronomy https://doi.org/10.1051/0004-6361/201936172 & c ESO 2020 Astrophysics Structure and kinematics of the Virgo cluster of galaxies? Olga G. Kashibadze1;??, Igor D. Karachentsev1, and Valentina E. Karachentseva2 1 Special Astrophysical Observatory of the Russian Academy of Sciences, Nizhnij Arkhyz, Karachay-Cherkessia 369167, Russia e-mail: [email protected] 2 Main Astronomical Observatory of the National Academy of Sciences, 27 Akademika Zabolotnoho St., Kyiv 03143, Ukraine Received 25 June 2019 / Accepted 24 January 2020 ABSTRACT Aims. This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities −1 ◦ ◦ VLG < 2600 km s situated within a region of ∆SGL = 30 and ∆SGB = 20 around M 87. About half of the galaxies have distance estimates. Methods. We selected 398 galaxies with distances in a (17 ± 5) Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster. Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extension filament. From a 1D 14 profile of the cluster, we obtain the virial mass estimate of (6:3 ± 0:9) × 10 M , which is in tight agreement with its mass estimate via the external infall pattern of galaxies. Conclusions. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius. Key words. galaxies: clusters: individual: Virgo 1. Introduction In this work, which is a continuation of the previous KKK18 study, we restrict our analysis with the region limited by ∆SGL = It is well known that a thousand of the brightest galaxies with ◦ ◦ m 30 and ∆SGB = 20 centred at M 87. The sample used in apparent magnitudes mB < 13 (Sandage & Tammann 1981) KKK18 was supplemented by galaxies with radial velocities form a planar structure across the sky, called the Local Super- −1 VLG = [2000−2600] km s and new distances from Cantiello cluster (de Vaucouleurs 1961). The most dense region of the et al.(2018) and Toloba et al.(2018). Local Supercluster (LSC) is the Virgo cluster of galaxies, It should be noted that the Virgo Cluster Catalog (VCC, with the centre usually identified by the radiogalaxy Virgo Binggeli et al. 1985) and the Extended Virgo Cluster Catalog A = M 87 = NGC 4486. (EVCC, Kim et al. 2014) have made a foundational contribu- In our previous paper (Kashibadze et al. 2018, KKK18), we tion to studies of the structure of the Virgo cluster. Both cat- considered the distribution and the radial velocity field of galax- alogues have expanded our insights into the dwarf population ies located within the equatorial belt of 100◦ by 20◦, centred ◦ of the nearest cluster of galaxies. Still, there are no measured on M 87 with its supergalactic coordinates SGL = 102.88 and radial velocities for most dwarf galaxies in the Virgo region, and − ◦ SGB = 2:35 . This region, including the whole Virgo cluster and their membership in the cluster is considered from some indirect its spurs, contains 2158 galaxies with radial velocities VLG < −1 indicators. Tonry et al.(2000) and Mei et al.(2007) performed 2000 km s relative to the Local group centroid. Half of them bulk distance measurements for members of the Virgo cluster. − have distance estimates D and peculiar velocities Vpec = VLG The surface-brightness-fluctuation method they had used pro- H0 × D, where H0 is the local Hubble parameter, which is set to −1 −1 vided distances for more than a hundred of the most bright E 73 km s Mpc . It has been found out that some galaxy groups in and S0 galaxies with an accuracy of ∼10−15%. The data are ∼ − −1 the belt have peculiar velocities up to (500 800) km s , com- very important for understanding the structure and the dynam- parable with virial velocities in rich clusters of galaxies. Using ics of the Virgo cluster, since radial velocities of galaxies in the the spherically symmetrical infall model, we estimated the radius ◦ vicinity of a massive attractor are ambiguous and uncertain indi- of the zero-velocity surface of the Virgo cluster as 23 , or cators of their distances. ± (7:8 0:3) Mpc, corresponding to the total mass of the clus- The ALFALFA HI-survey of galaxies in Arecibo (Haynes ± × 14 ter MT = (7:4 0:9) 10 M . Shaya et al.(2017) obtained et al. 2011, 2018) brought radial velocities and HI-line widths nearly the same value of the radius of the zero-velocity surface, for many late-type galaxies in the Virgo cluster area. This ± (7:3 0:3) Mpc, considering trajectories of galaxies within the allowed us to estimate new distances for 380 irregular and spiral Numerical Action Method. galaxies in the sky region in question, doubling the total num- ? Full Table 1 is only available at the CDS via anonymous ftp ber of galaxies with known distances. This progress in distance to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc. estimates provided us with an opportunity to review the structure u-strasbg.fr/viz-bin/cat/J/A+A/635/A135 and dynamics of the Virgo cluster again. In total, we have a sam- ?? f.k.a. Nasonova. ple of 1537 galaxies inside the area of 30◦ by 20◦ with measured Article published by EDP Sciences A135, page 1 of9 A&A 635, A135 (2020) Table 1. Galaxies around M 87 with supergalactic coordinates SGL = [87.9, 117.9]◦, SGB = [−12.4, +7.6]◦, and radial velocities −1 VLG < 2600 km s . Name RA (2000) Dec SGL SGB Rp VLG Type BT KW50 m21 m − MD Meth (◦)(◦)(◦) (km s−1) (mag) (mag) (km s−1) (mag) (mag) (Mpc) PGC1664006 J113206.6+220731 88.93 −12.33 17.05 1091 Im 17.36 15.01 47 18.08 31.28 18.00 TF PGC1620526 J113554.4+201320 91.08 −12.24 15.31 1038 I 17.04 14.69 108 17.69 . PGC1597887 J113908.9+193460 91.97 −11.77 14.34 1636 I 18.28 15.93 . UGC06670 J114229.4+181959 93.45 −11.49 13.08 823 I 13.56 11.21 194 14.60 31.29 18.10 TF PGC1519757 J114440.7+165359 95.01 −11.51 12.04 813 BCD 16.98 14.63 91 17.97 . UGC06747 J114624.0+134938 98.11 −12.18 10.91 2574 Sdm 16.27 13.67 96 15.30 31.53 20.30 TFb EVCC2007 J114626.5+193012 92.69 −10.19 12.80 2086 Im 19.16 16.81 102 17.66 33.78 57.10 TFb AGC219628 J114714.0+184028 93.54 −10.31 12.22 1746 Sm 18.50 16.15 77 17.49 32.73 35.10 TFb SDSSJ114717 J114717.5+162005 95.77 −11.12 11.26 700 E 17.97 13.87 . PGC2806928 J114816.4+183833 93.65 −10.09 12.00 876 Im 16.64 14.29 65 16.41 31.31 18.24 TF SDSSJ114843 J114843.1+171053 95.08 −10.50 11.24 963 I 17.38 15.03 42 17.72 30.92 15.31 TF AGC219539 J114845.0+164423 95.51 −10.65 11.07 1510 I 18.60 16.25 72 17.18 32.64 33.85 TFb DDO097 J114857.4+235016 88.79 −8.09 15.16 452 I 15.12 12.77 86 15.50 30.69 13.74 bs PGC1528400 J114905.6+171520 95.04 −10.39 11.19 519 BCD 18.06 15.71 . AGC219541 J114921.7+171724 95.03 −10.32 11.15 1266 Im 18.20 15.85 66 17.50 32.55 32.33 TFb SDSSJ114931 J114931.0+151540 96.99 −10.98 10.42 747 E 17.85 13.75 . SDSSJ114957 J114957.1+161744 96.03 −10.53 10.64 1110 I 18.11 15.76 33 18.34 30.89 15.10 TF PGC036976 J115002.7+150124 97.26 −10.94 10.24 638 BCD 15.43 13.08 47 16.80 30.67 13.60 TF PGC037048 J115055.9+143542 97.74 −10.88 9.94 893 Im 15.52 13.17 52 15.70 30.32 11.60 TF KIG0506 J115201.9+135244 98.52 −10.87 9.56 847 I 16.12 13.77 79 16.61 31.31 18.30 TF SDSSJ115220 J115220.2+152736 97.03 −10.27 9.82 676 Im 17.53 15.18 68 17.65 . SDSSJ115300 J115300.3+160230 96.53 −9.93 9.86 823 I 18.53 16.18 23 19.93 . KK111 J115401.6+164323 95.96 −9.47 9.90 879 I 17.06 14.71 41 16.77 30.32 11.59 TFb AGC215145 J115412.5+122606 100.09 −10.84 8.93 880 I 19.00 16.65 32 16.80 29.57 8.20 TFb UGC06881 J115444.9+200323 92.85 −8.17 11.56 522 I 15.83 13.48 90 16.20 31.07 16.40 TF NGC3976 J115557.4+064459 105.74 −12.22 10.27 2348 Sb 12.45 8.60 436 13.27 32.53 32.70 tf PGC037490 J115602.5+064041 105.81 −12.23 10.30 2354 S0 15.83 11.73 . AGC215716 J115707.2+064032 105.90 −11.97 10.08 2358 Sm 17.70 15.35 100 17.39 33.75 56.20 TF PGC1488625 J115840.4+153534 97.42 −8.79 8.43 458 I 18.28 15.93 .
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