LGG 6 LGG 9 LGG 14 LGG 18 CLoGS: the complete NGC 193 NGC 315 local-volume groups sample NGC 128 NGC 410 1 2 1 1 E. O’Sullivan , K. Kolokythas , J.M. Vrtilek , L. David , NGC 407 G. Schellenberger1, M. Gitti3, S. Giacintucci4, A. Babul5, 6 1: Harvard-Smithsonian Center for Astrophysics, 2: North-West University, South Africa & S. Raychaudhury 3: Universitá di Bologna & INAF-Instituto di Radioastronomia, 4: Naval Research Laboratory, 5: University of Victoria, Canada, 6: IUCAA, India 5' 2' 5' 5' LGG 42 LGG 72 LGG 97 LGG 100 LGG 103 LGG 113 LGG 31 Background NGC 1407 Cluster Background Cluster NGC 1395 NGC 1550 NGC 777 NGC 1066 NGC 1453 NGC 677 NGC 1060 NGC 1400 5' 5' 5' 5' 5' 5' 5' LGG 12 LGG 23 LGG 27 LGG 58 LGG 61 LGG 158 LGG117 Galaxy groups in the local universe: CO survey O’Sullivan et al. (2015, 2018) A&ABackground 573, A111 and A&A 618, A126 results from a complete sample Group Background: Galaxy groups are arguably the most important environment for our understandingNGC 252 of galaxy evolution, AGN feedback,NGC and 524 the development of NGC 2563 NGC 584 NGC 924 the hot intra-group and intra-cluster medium. Most previous studies of groups NGC 940 NGC 1587 have either used optically-selected samples to examine galaxy populations, or X-ray selected samples (usually derived from the Rosat All-Sky Survey) to investigate gas properties. While these approaches have yielded important results, their selection methods mean they are subject to significant biases. 4' Optically-selected5' samples often include false groups, since at low masses 5' 4' 5' 5' 5' selection must be made using only a few galaxies. X-ray selection tends to LGG 167 LGG 66 LGG 78 LGG 80 LGG 126 LGG 138 LGG 185 produce samples dominated by cool-core systems with centrally-concentrated surface brightness, since these central peaks are most easily detected. Background Cluster Sample: We have created the Complete Local-Volume Groups Sample NGC 2768 (CLoGS), an optically-selected statistically-complete sample of 53 groups in the NGC 1106 NGC 1779 nearby Universe (D<80 Mpc), with complete coverage in the X-ray (Chandra NGC 1167 NGC 3078 and XMM-NewtonNGC), multi-frequency978 radio (GMRT 235 and 610 MHz) and, for the NGC 2292 dominant galaxies, CO (IRAM 30m and APEX). This combination of data allows Background us to examine the gas content of the groups, their dynamical state, and the role Cluster of AGN feedback in maintaining their thermal balance. 2' We5' select our sample from the Lyon5' Galaxy Group catalogue (LGG, Garcia5' 5' 5' 5' LGG 236 1993, A&AS 100, 47), choosingLGG 177 groups which have: LGG 205 LGG 232 LGG 255 LGG 262 LGG 278 • ≥ 4 member galaxies (excluding pairs & triples which may lack a common halo) All 53 group-dominant early-type galaxies have been observed in CO(2-1) • ≥ 1 early-type member (as spiral-only groups tend to be hot gas poor) and/or CO(1-0) using the IRAM 30m or APEX telescopes. We detect CO in 21 7 10 galaxies (~40%), with masses 1-610 x10 M¤. This detection rate is roughly • Optical luminosity LB > 3x10 L¤ for the brightest member Background double that of the general early-type population. Comparing radio luminosity to QSO • Declination > -30° (to ensure visibility from GMRT and VLA) NGC 4261 NGC 3665 molecular gas mass (see Figure above),NGC 3923 we find that while some of our galaxies We then expand andNGC 2911refine the galaxy membershipNGC 3325 using the LEDA galaxy NGC 3613 NGC 4008 catalogue, and exclude systems judged to be too rich (clusters) or too poor (too have properties consistent with star formation (the grey band), a large fraction are AGN dominated. However, the presence of CO is not clearly linked to radio few NGCgalaxies 2914 to characterize the population). power, or to the presence of hot gas. This suggests that while group-dominant For more details of sample selection and X-ray properties, see galaxies can build up a CO reservoir through cooling from the hot halo (as in O’Sullivan et al. (2017, MNRAS 472, 1482). galaxy clusters), many acquire it through gas-rich mergers. 5' 5' 5' 5' 5' 5' 5' LGG 310 LGG 276 LGG 329 LGG 341 LGG 345 LGG 351 LGG 314 Radio properties X-ray properties Kolokythas et al. (2018, 2019) MNRAS, 481, 1550 and MNRAS, 489, 2488 Group detection fraction: Of our 53 systems, 41 NGC 4697 ESO 507-25 • 26 (~50%) have a full group-scale X-ray halo (>65 kpc extent, LX>10 erg/s) NGC 4169 NGC 4956 NGC 5061 NGC 5084 40 41 NGC 5153 • 16 (~30%) have a galaxy-scale halo (LX=10 -10 erg/s) NGC 4175 • the remainder have only point-source emission in the dominant galaxy. Of the group-scale halos, ~1/3 are dynamically active, showing signs of ongoing mergers or sloshing (indicating a recent minor merger or tidal encounter). Roughly 65% have cool cores, a higher fraction than in clusters (~50%). Unlike 4' 5' 5' 5' clusters, many of 4'the merging groups retain their cool4' cores. The temperature 5' LGG 338 13 LGG 350 LGG 421 range ofLGG our 457 systems is ~0.4-1.5 keV, equivalentLGG 463 to masses of ~0.5-5 x10 M¤. New groups Background One goal of our sample was to search for new groups, previously undetected in Cluster the X-ray. Of our 26 systems with a full-scale intra-group medium (IGM), 12 were NGC 5044 NGCidentified 7252 as X-ray bright groups NGCfor the7377 first time, of which 8 were undetected NGC 6658 in the Rosat All-Sky Survey (RASS). Examples include: LGG 402 / NGC 5982 41 (bottom row) a faint (LX=3x10 erg/s), cool (0.59 keV) group which lacks a cool NGC 5127 core; LGG 72 / NGC 1060 (above left) a train-wreck merger with a 100 kpc arc of stripped gas linking the two cores; and LGG 398 / NGC 5903 (bottom row) in Our GMRT 235 and 610 MHz observations (~4hrs/target, rms ~0.1mJy/bm which a combination of galaxy interactions and a powerful AGN outburst seem to @610 MHz, ~0.6mJy/bm @ 235 MHz) are well suited to identifying AGN over a have disrupted the5' group core (see O’Sullivan et al. 2018 MNRAS, 473, 5248 for 5' wide range of scales and ages. For the5' group-dominant ellipticals we find:5' 5' more details). In each case, the lack of a relaxed cool core with a strong surface LGG 360 LGG 363 brightness peak probably explains the RASS non-detection. • 46/53 (87%) are detected in our GMRT data (or the NVSS or FIRST surveys) • 13 host jet sources (implying a duty cycle ~1/3) Future plans • 28 host point-like sources NGC 5350 We are currently working on several aspects of the sample, including: • 5 host diffuse sources (e.g., LGGs 31, 117, 185, 310). The origin of emission • MUSE observations of 17 dominant galaxies, providing information on stellar NGC 5354 in these sources is unclear (star formation? disrupted jets? radio phoenices?) NGC 5322 populations and cooling from the hot gas halo. NGC 5353 • Collecting interferometric observations of our CO-detected systems (via 11 of the 13 galaxies with jet sources reside in systems with group-scale NOEMA and ALMA/ACA) to map the gas and understand its origin. X-ray halos and cool cores. The plot above shows cavity enthalpy vs. cooling • Detailed studies of particularly interesting individual systems, e.g., the time (P vs L ) for 5 of our richest groups. Three fall on the relation, with cav cool asymmetric radio source in LGG 113 / NGC 1550. cooling and heating in balance, but two (LGGs 9 and 278) have P =50xL , cav cool • Expanding the sample to include southern and spiral-dominated groups. suggesting that these AGN may be dramatically over-heating their groups. 5' 5' LGG 370 LGG 376 LGG 383 LGG 393 LGG 398 LGG 402 LGG 473 NGC 5846 NGC 7626 NGC 5903 NGC 5982 NGC 7619 NGC 5444 NGC 5490 NGC 5629 NGC 5985 NGC 5898 5' 5' 5' 5' 5' 5' 5' CLoGS gallery: Each panel shows an adaptively smoothed 0.5-2 keV image of a CLoGS group, with an 2.5’x2.5’ optical (DSS or SDSS) image of the dominant early-type galaxy inset. For radio-detected systems, GMRT 610 or 235 MHz contours are overlaid. http://www.sr.bham.ac.uk/~ejos/CLoGS.html.