SCG 0018-4854: A YOUNG AND DYNAMIC GROUP V. Presotto1,2, A. Iovino1 , E. Pompei 3, G. Temporin4 Goodmorning everybody, during these days we have travelled back to the origin of the universe, now I will bring you back to the local universe talking about SCG0018 a young and dynamic compact group. 1INAF-OABrera, Milano, I 2Università dell’Insubria, Como, I 3ESO-Chile 4Institute fur Astrophysik, Innsbruck, A 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- OUTLINE What are compact groups and why they are important? SCG0018-4854 Results Conclusions 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- COMPACT GROUPS (CGs) Selection criteria: Richness: n≥4 with (m≤m1+3) Isolation: RN≥3RG Compactness: mG<26mag∙arcsec-2 Properties: Low dispersion: <s>≈200km/s High density: 300<dgroup<108h2Mpc-2 Lifetime ? tcross≈0.016 1/H0 (Hickson 1982;1992) Stephan’s quintet SCGs sample: Dmmember<Dmiso Dm=mest-mint>4 (Iovino 2002) Let me spend just few words to introduce you what are compact group. They are small, compact and isolated systems of few galaxies. Their most important characteristics are high density and low velocity dispersion. SCG0018 is part of the SCGs catalogue Seyfert’s sextet NEW 24-29 May 2009 Lucchin School -Bertinoro-

INTERACTIONS IN CGs Compact groups are perfect laboratories to test galaxies’ interactions Tidal forces => morphological distorsion and disturbed kinematics Gas infall => triggering of strong burst of star formation or feeding an AGN Galaxies merger => new galaxy + TDGs Aim: reveal evidence of interaction in SCG 0018-4854 to investigate its evolution history Compact groups are perfect laboratories to test galaxies interactions due to their typical density and dispersion. Infact tidal forces are really efficient in this environment. As a result, many galaxies in compact groups show morphological distortion, disturbed kinematic and intense activity. We then decide to reveal evidences of interaction in SCG0018 to investigate its evolutionary history. 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- SCG 0018-4854 From the SCGs cat (Iovino 2002) redshift: V≈3300 km/s (≈46Mpc) richness: 4 gal in close proximity, R≈20 kpc density2: 104.88 gal/Mpc-3 velocity dispersion2: ≈120 km/s Galaxy V1 (km/s) Class2 Activity2 Notes A (NGC 92) 3384 Saap SBG Tidal tail Double nuclei 3 B (NGC 89) 3284 SB0/a pec Sy2 Outflow 4 C (NGC 87) 3415 Irr SFG --- D (NGC 88) 3432 SBab pec LINER SCG0018 is a remarkably high density and low velocity dispersion group located at approximately 46 Mpc and it is composed by 4 gals. All four close members show disturbed morphology and late-type appearance. Note the extended tidal tail of gal A which was also supposed to have a double nucleus and gal B has a galactic-scale outflow well visible in Ha. Moreover all gals show intense activity. 1 This work 2 Pompei et al. 2007 3 Danks & Alcaino 1981 4 Temporin et al. 2005 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- SCG 0018-4854 Data from FORS2 @ VLT/ESO Multi-slit spectroscopy: M & m axis (except M axis NGC 88) Grism: 1400V with l0 5200Å 20.8Å/mm (0.49 Å/px) Texp: 4X2699s Photometry: all gal Filters: 1. R-band 6550Å (FWHM 1650Å) 2. Ha 6615Å (FWHM 61Å) Texp: 3X119s (R-band) 3X100s (Ha) R-band The study is based on VLT observations, we obtained spectra along both axis of each gal and R-Ha imaging. Here I summarize the main results of the study. 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 92 Let’s start with NGC 92 the dominant gal of the group 24-29 May 2009 Lucchin School -Bertinoro-

NGC 92 Ha K Asymmetric gas radial velocity curve: AP=23% => recent interaction: presence of a 8-shape1 along minor axis => Nuclear bar misaligned with respect to PA major axis Major axis kinematic reveal two main feature: gas rotates faster than stars and moreover it has an asymmetric rotation curve. We quantify this asymmetry with the AP. We obtain an high value which is a sign of recent interaction. Moreover we found double components in the emission line profile along the minor axis tracing an 8-shape. This is the sign of the presence of a nuclear bar. Therefore the bright knot thought to be a second nucleus is actually the elbow of the spiral arm pointing towards the observer as can be seen in the Ha and K-band image. 0.2Gyr<tcoll<0.7Gyr 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 89 Let’s talk about NGC 89. 24-29 May 2009 Lucchin School -Bertinoro-

NGC 89 Fig D Asymmetric stellar/gas radial velocity curve: AP=33-24% => recent interaction: 0.2Gyr<tcoll<0.7Gyr NLR: presence of gas multiple components (3/4) Once again we find asymmetric and perturbed kinematic along major axis which are consistent with recent interaction at least within the last 0.7 Gyr. Moreover this is a Sy2 gal and in the inner regions the emission line profiles are quite complex. There’s the presence of multiple gas components, we fit it with at least ¾ . 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 89 Ha Temporin et al. 2005 Slit along minor axis intercepts the galactic-scale outflow. We obtain spectroscopical confirmation of this outflow and as we can see in the plot there’s not a clear correlation between outflow and surrounding gas. Green triangles are the outflow whereas blue circles is the gas. SW direction: steep rise of gas velocity Spectroscopical confirmation of the galactic-scale outflow Not clear correlation between outflow & surrounding gas 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 88 Just few words for the other two gals: NGC 88 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 88 R-band We found a low surface brightness tidal tail in the SW direction which is the opposite direction with respect to GC 92, the other gal with a tidal tail. Moreover there’s a sort o regular pattern of rotation of the gas along minor axis. Low surface brightness tidal tail ≈14x10kpc SW direction Gas => regular pattern of rotation 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- NGC 87 24-29 May 2009 Lucchin School -Bertinoro-

NGC 87 (major & minor axis) Ha Face-on irregular Star forming regions Ha Velocity gradients along M&m axis + peculiar motions NGC 87 is a face-on irregular and we found velocity gradients along both axis. 24-29 May 2009 Lucchin School -Bertinoro-

CONCLUSIONS We found peculiar kinematics and morphological distortions probably due to interactions among galaxies No double nucleus for NGC 92 Recent interaction: 0.2Gyr<tcoll<0.7Gyr Spectroscopical confirmation of the galactic-scale outflow of NGC 89 In conclusion we found peculiar kinematics and morphological distortions probably due to interactions among galaxies recent interaction: 0.2Gyr<tcoll<0.7Gyr Spectroscopical confirmation of the galactic-scale outflow of NGC 89 Presotto et al. 2009 in preparation 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- Thanks 24-29 May 2009 Lucchin School -Bertinoro-

SCG 0018-4854 X-ray KT ≈ 0.2 keV => coolest system detected so far Coda mareale Regioni isolate Ha Emissione diffusa Ha Asy level + immagine Trinchieri et al. 2008 KT ≈ 0.2 keV => coolest system detected so far 24-29 May 2009 Lucchin School -Bertinoro-

SCG 0018-4854 X-ray Phase 3b Hi bridge between NGC 92 and NGC 88 NGC 89 completely stripped of HI Pompei et al.2007 24-29 May 2009 Lucchin School -Bertinoro-

Lucchin School -Bertinoro- SCG 0018-4854 gal properties Galaxy V1 (km/s) Class2 Activity2 Notes B mag1 M H (109 Mo)I A (NGC 92) 3384 Saap SBG Tidal tail Double nuclei 3 13.81 >3.29 B (NGC 89) 3284 SB0/a pec Sy2 Outflow 4 14.18 <0.02 C (NGC 87) 3415 Irr SFG --- 14.67 0.81 D (NGC 88) 3432 SBab pec LINER 14.98 2.52 24-29 May 2009 Lucchin School -Bertinoro-