On the Structure of the Coma Cluster of Galaxies

Baier, F. W.

doi:10.1002/asna.2113050403

“…It is believed that Coma has recently undergone a cluster-subcluster merger (Burns et al 1994b). This has been confirmed by several optical studies (Baier 1984;Fitchett & Webster 1987;Mellier et al 1988;Caldwell et al 1993;Zabludoff, Franx, & Geller 1993;Colless & Dunn 1996); however, the optical state of this cluster is still poorly understood (e. g. Geller & Beers 1982;Dressler & Schectman 1988;West & Bothun 1990). The merger hypothesis is supported by filamentary X-ray emission in the E and SE detected through a wavelet analysis (Vikhlinin, Forman & Jones 1997), and smaller X-ray subclumps detected by the Einstein IPC (Davis & Mushotzky 1993).…”

Section: O N C L U S I O N Ssupporting

confidence: 52%

“…Caldwell et al (1993) detected a number of 'EþA' (Dressler & Gunn 1983) galaxies, which are almost exclusively located to the SW of the cluster centre. This is a surprising result, since most of these post-starburst galaxies are detected in distant (z ϳ 0:2) clusters (Butcher & Oemler 1978, 1984Dressler & Gunn 1983;Couch & Sharples 1987). Abell 1795: Fig.…”

Section: A P P E N D I X a : I N D I V I D Ua L S O U R C E Smentioning

confidence: 94%

Cluster-subcluster mergers and the formation of narrow-angle tailed radio sources

Bliton¹,

Rizza²,

Burns³

et al. 1998

Monthly Notices of the Royal Astronomical Society

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firstpage-lastpage 1998 document firstpage abstract We have examined the ROSAT PSPC X-ray properties of a sample of 15 Abell clusters containing 23 narrow-angle tailed (NAT) radio galaxies. We find that clusters with NATs show a significantly higher level of substructure than a similar sample of radio-quiet clusters, indicating that NAT radio sources are preferentially located in dynamically complex systems. Also, the velocity distribution of the NAT galaxies is similar to that of other cluster members; these velocities are inadequate for producing the ram pressure necessary to bend the radio jets. We therefore propose a new model for NAT formation, in which NATs are associated with dynamically complex clusters undergoing merger events. The U-shaped NAT morphology is produced in part by the merger-induced bulk motion of the ICM bending the jets.

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“…It is believed that Coma has recently undergone a cluster-subcluster merger (Burns et al 1994b). This has been confirmed by several optical studies (Baier 1984;Fitchett & Webster 1987;Mellier et al 1988;Caldwell et al 1993;Zabludoff, Franx, & Geller 1993;Colless & Dunn 1996); however, the optical state of this cluster is still poorly understood (e. g. Geller & Beers 1982;Dressler & Schectman 1988;West & Bothun 1990). The merger hypothesis is supported by filamentary X-ray emission in the E and SE detected through a wavelet analysis (Vikhlinin, Forman & Jones 1997), and smaller X-ray subclumps detected by the Einstein IPC (Davis & Mushotzky 1993).…”

Section: O N C L U S I O N Smentioning

confidence: 53%

“…Caldwell et al (1993) detected a number of 'EþA' (Dressler & Gunn 1983) galaxies, which are almost exclusively located to the SW of the cluster centre. This is a surprising result, since most of these post-starburst galaxies are detected in distant (z ϳ 0:2) clusters (Butcher & Oemler 1978, 1984Dressler & Gunn 1983;Couch & Sharples 1987). Abell 1795: Fig.…”

Section: A P P E N D I X a : I N D I V I D Ua L S O U R C E Smentioning

confidence: 99%

Cluster-subcluster mergers and the formation of narrow-angle tailed radio sources

Bliton

¹

,

Rizza

²

,

Burns

³

et al. 1998

Monthly Notices RAS

View full text Add to dashboard Cite

firstpage-lastpage 1998 document firstpage abstract We have examined the ROSAT PSPC X-ray properties of a sample of 15 Abell clusters containing 23 narrow-angle tailed (NAT) radio galaxies. We find that clusters with NATs show a significantly higher level of substructure than a similar sample of radio-quiet clusters, indicating that NAT radio sources are preferentially located in dynamically complex systems. Also, the velocity distribution of the NAT galaxies is similar to that of other cluster members; these velocities are inadequate for producing the ram pressure necessary to bend the radio jets. We therefore propose a new model for NAT formation, in which NATs are associated with dynamically complex clusters undergoing merger events. The U-shaped NAT morphology is produced in part by the merger-induced bulk motion of the ICM bending the jets.

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“…The present study extends the photometry of BLE92a to a complete galaxy sample covering approximately four times the area (still centred on the core), and reaches to fainter limiting magnitudes. The extra coverage and depth will enable us to obtain colours for the abnormal spectrum ‘’ galaxies of Caldwell et al (1993; 1996), many of which are to be found in the south‐west corner of the cluster around a group of galaxies dynamically associated with NGC 4839 (Baier 1984; Escalera, Slezak & Mazure 1992; Colless & Dunn 1996). Significant advances in detector technology since the work of BLE92a allow us to use much larger CCDs with greater U ‐band sensitivity.…”

Section: Introductionmentioning

confidence: 99%

The colour-magnitude relation for galaxies in the Coma cluster

Terlevich

¹

,

Caldwell

²

,

Bower

³

2001

Monthly Notices of the Royal Astronomical Society

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We present a new photometric catalogue of the Coma galaxy cluster in the Johnson U and V bands. We cover an area of 3360 arcmin2 of sky, to a depth of in a 13‐arcsec diameter aperture, and produce magnitudes for ∼1400 extended objects in metric apertures from 8.8‐ to 26‐arcsec diameters. The mean internal rms scatter in the photometry is 0.014 mag in V, and 0.026 mag in U, for . We place new limits on the levels of scatter in the colour–magnitude relation (CMR) in the Coma cluster, and investigate how the slope and scatter of the CMR depend on galaxy morphology, luminosity and position within the cluster. As expected, the lowest levels of scatter are found in the elliptical galaxies, while the late‐type galaxies have the highest numbers of galaxies bluewards of the CMR. We investigate whether the slope of the CMR is an artefact of colour gradients within galaxies, and show that it persists when the colours are measured within a diameter that scales with galaxy size. Looking at the environmental dependence of the CMR, we find a trend of systematically bluer galaxy colours with increasing projected radius from the centre of the cluster. Surprisingly, this is accompanied by a decreased scatter of the CMR. We investigate whether this gradient could be caused by dust in the cluster potential, however the reddening required would produce too large a scatter in the colours of the central galaxies. The gradient appears to be better reproduced by a gradient in the mean galactic ages with projected radius.

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On the Structure of the Coma Cluster of Galaxies

Cited by 11 publications

References 43 publications

Cluster-subcluster mergers and the formation of narrow-angle tailed radio sources

Cluster-subcluster mergers and the formation of narrow-angle tailed radio sources

Cluster-subcluster mergers and the formation of narrow-angle tailed radio sources

The colour-magnitude relation for galaxies in the Coma cluster

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