Fast Motions of Galaxies in the Coma I Cloud: A Case of Dark Attractor?

Караченцев, И. Д.; Nasonova, O. G.; Courtois, H. M.

doi:10.1088/0004-637x/743/2/123

Cited by 21 publications

(20 citation statements)

References 44 publications

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“…Numerous simulations of the evolution of large-scale structure [5,6] reveal the presence of coherent motions of field galaxies with amplitudes of a few hundred km/s on the scale of approximately (10-50) Mpc. The observational data on large peculiar motions of galaxies in the Coma I region give indications that there exists a possible "dark attractor" with a mass of around 10 14 M ⊙ at the distance of 15 Mpc from us [18].…”

Section: Discussionmentioning

confidence: 99%

Low density structures in the local universe. I. Diffuse agglomerates of galaxies

et al. 2012

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This paper is the first of a series considering the properties of distribution of nearby galaxies in the low density regions. Among 7596 galaxies with radial velocities V LG < 3500 km/s, absolute magnitudes M K < −18. m 4, and Galactic latitudes |b| > 15• there are 3168 field galaxies (i.e. 42%) that do not belong to pairs, groups or clusters in the Local universe.Applying to this sample the percolation method with a radius of r 0 = 2.8 Mpc, we found 226 diffuse agglomerates with n ≥ 4 number of members. The structures of eight most populated objects among them (n ≥ 25) are discussed. These non-virialized agglomerates are characterized by a median dispersion of radial velocities of about 170 km/s, the linear size of around 6 Mpc, integral K-band luminosity of 3 × 10 11 L ⊙ , and a formal virial-massto-luminosity ratio of about 700 M ⊙ /L ⊙ . The mean density contrast for the considered agglomerates is only ∆n/n ∼ 5, and their crossing time is about 30-40 Gyr.

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Section: Discussionmentioning

confidence: 99%

Low density structures in the local universe. I. Diffuse agglomerates of galaxies

et al. 2012

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“…Further complicating the nearby velocity field is the Coma I cloud just north of the HI1232+20 system. This complex of galaxies with peculiar velocities is centered around (α, δ) = (12.5h, +30 • ) (Karachentsev et al 2011). Still, we can make a crude but reliable estimate of the lower limit on the distance based on the fact that we do not resolve any individual stars in the optical counterpart of AGC 229385.…”

Section: Effects Of Distance Uncertainty and The Environmentmentioning

confidence: 93%

(Almost) Dark Hi Sources in the Alfalfa Survey: The Intriguing Case of Hi1232+20

Janowiecki

Józsa

Salzer

et al. 2015

ApJ

147

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We report the discovery and follow-up observations of a system of three objects identified by the ALFALFA extragalactic HI survey, cataloged as (almost) dark extragalactic sources, i.e., extragalactic HI detections with no discernible counterpart in publicly available, wide-field, imaging surveys. We have obtained deep optical imaging with WIYN pODI and HI synthesis maps with WSRT of the HI1232+20 system. The source with the highest HI flux has a newly discovered ultra-low surface brightness (LSB) optical counterpart associated with it, while the other two sources have no detected optical counterparts in our images. Our optical observations show that the detected LSB optical counterpart has a peak surface brightness of ∼26.4 mag/arcsec 2 in g , which is exceptionally faint. This source (AGC 229385) has the largest accurately measured HI mass-to-light ratio of an isolated object: M HI /L g =46 M /L , and has an HI mass of 7.2×10 8 M . The other two HI sources (with HI masses 2.0×10 8 and 1.2×10 8 M ) without optical counterparts have upper limit surface brightnesses of 27.9 and 27.8 mag/arcsec 2 in g , and lower limits on their gas mass-to-light ratio of M HI /L g >57 and >31 M /L . This system lies relatively close in projection to the Virgo Cluster, but velocity flow models indicate that it is located at 25 Mpc, substantially beyond Virgo. The system appears to be quite isolated, with no known object closer than ∼500 kpc. These HI sources may represent both sides of the threshold between "dark" star-less galaxies and galaxies with stellar populations. We discuss a variety of possible formation scenarios for the HI1232+20 system.

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“…As NGC 4414 is part of a group environment it is likely that (unless it is falling in the first time) it will have undergone some interaction with other group members in the past. The peculiar motions of galaxies in the Coma I region are however complex (Karachentsev et al 2011) and it is difficult to unambiguously define a candidate galaxy that could have caused the current H  morphology of NGC 4414.…”

Section: A U-shaped Warpmentioning

confidence: 99%

HALOGAS observations of NGC 4414: fountains, interaction, and ram pressure

Blok

Józsa

Patterson

et al. 2014

A&A

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We present deep H  imaging of the nearby spiral galaxy NGC 4414, taken as part of the Westerbork HALOGAS (Hydrogen Accretion in LOcal GAlaxieS) survey. The observations show that NGC 4414 can be characterized by a regularly rotating inner H  disk, and a more disturbed outer disk. Modeling of the kinematics shows that the outer disk is best described by a U-shaped warp. Deep optical imaging also reveals the presence of a low surface brightness stellar shell, indicating a minor interaction with a dwarf galaxy at some stage in the past. Modeling of the inner disk suggests that about 4 percent of the inner H  is in the form of extra-planar gas. Because of the disturbed nature of the outer disk, this number is difficult to constrain for the galaxy as a whole. These new, deep observations of NGC 4414 presented here show that even apparently undisturbed galaxies are interacting with their environment.

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Fast Motions of Galaxies in the Coma I Cloud: A Case of Dark Attractor?

Cited by 21 publications

References 44 publications

Low density structures in the local universe. I. Diffuse agglomerates of galaxies

Low density structures in the local universe. I. Diffuse agglomerates of galaxies

(Almost) Dark Hi Sources in the Alfalfa Survey: The Intriguing Case of Hi1232+20

HALOGAS observations of NGC 4414: fountains, interaction, and ram pressure

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