The properties of early-type galaxies in the Ursa Major cluster

Pak, Mina; Rey, Soo-Chang; Lisker, Thorsten; Lee, Youngdae; Kim, S.; Sung, Eon‐Chang; Jerjen, Helmut; Chung, Jiwon

doi:10.1093/mnras/stu1722

Cited by 35 publications

(59 citation statements)

References 90 publications

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“…Major (Pak et al 2014, and references therein) have noted the presence of tidal gas around NGC 3998, which is also seen in the Serra et al (2012) results. This is likely connected to the fact that NGC 3998 is located in a region of fairly high galaxy density (Cappellari et al 2011b).…”

Section: Overview Of Ngc 3998supporting

confidence: 62%

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

Frank

Morganti

Oosterloo

et al. 2016

A&A

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We study the nearby lenticular galaxy NGC 3998. This galaxy is known to host a low-power radio AGN with a kpc-size one-sided jet and a large, nearly polar H i disc. It is therefore a good system to study to understand the relation between the availability of cold-gas and the triggering of AGNs in galaxies. Our new WSRT data reveal two faint, S-shaped radio lobes extending out to ∼10 kpc from the galaxy centre. Remarkably, we find that the inner H i disc warps back towards the stellar mid-plane in a way that mirrors the warping of the radio lobes. We suggest that the polar H i disc was accreted through a minor merger, and that the torques causing it to warp in the inner regions are also responsible for feeding the AGN. The "S" shape of the radio lobes would then be due to the radio jets adapting to the changing angular momentum of the accreted gas. The extended radio jets are likely poorly collimated, which would explain their quick fading and, therefore, their rarity in galaxies similar to NGC 3998. The fuelling of the central super-massive black hole is likely occurring via "discrete events", suggested by the observed variability of the radio core and the extremely high core dominance, which we attribute to the formation and ejection of a new jet resulting from a recent fuelling event.

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Section: Overview Of Ngc 3998supporting

confidence: 62%

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

Frank

Morganti

Oosterloo

et al. 2016

A&A

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“…(Müller et al 2015), and M106 group (Kim et al 2011), respectively. The dashed line denotes the color-magnitude relation obtained from the early-type galaxies in less massive and less dense Ursa Major cluster (Pak et al 2014), while the dotted line from the early-type dwarf galaxies in more massive and more dense Virgo cluster (Lisker et al 2008). , and Sérsic-n (c) versus total absolute magnitudes of the dwarf galaxies.…”

Section: Discussionmentioning

confidence: 99%

“…The (B − V ) 0 mean color is similar to those for the M106 ( (B − V ) 0 ≈ 0.73; Kim et al 2011) and the M83 groups ( (B − V ) 0 ≈ 0.82; Müller et al 2015). For comparison, we overlay the values of dwarf galaxies in other groups (M83 from Müller et al (2015), M106 from Kim et al (2011)) and the colormagnitude relations of the early-type galaxies in clusters (Virgo from Lisker et al (2008), and Ursa Major from Pak et al (2014)). We conclude that the color distributions are consistent and that the NGC 2784 dwarfs are mostly early-type galaxies.…”

Section: Comparison To Dwarf Galaxies In Other Systemsmentioning

confidence: 99%

Dwarf Galaxy Discoveries from the KMTNet Supernova Program. I. The NGC 2784 Galaxy Group^*

Park

Moon

Zaritsky

et al. 2017

ApJ

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We present BV I surface photometry of 31 dwarf galaxy candidates discovered in a deep image stack from the KMTNet Supernova Program of ∼ 30 square degrees centered on the nearby NGC 2784 galaxy group. Our final images have a 3σ surface brightness detection limit of µ V ≈ 28.5 mag arcsec −2 . The faintest central surface brightness that we measure is µ 0,V = 26.1 mag arcsec −2 . If these candidates are at the distance of NGC 2784, then they have absolute magnitudes greater than M V = −9.5 mag and effective radii larger than 170 pc. Their radial number density decreases exponentially with distance from the center of NGC 2784 until it flattens beyond a radius of 0.5 Mpc. We interpret the baseline density level to represent the background contamination and so estimate that 22 of the 31 new candidates are dwarf members of the group. The candidate's average color, (B − V ) 0 ≈ 0.7, and Sérsic structural parameters are consistent with those parameters for the dwarf populations of other groups. We find that the central population of dwarfs is redder and brighter than the rest of the population. The measured faint end slope of the luminosity function, α ≈ −1.33, is steeper than that of the Local Group but consistent with published results for other groups. Such comparisons are complicated by systematic differences among different studies, but will be simpler when the KMTNet survey, which will provide homogenous data for 15 to 20 groups, is completed.

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“…Côté et al 2007;Chen et al 2010;Kormendy & Bender 2012), but also since their identification Appendices are available in electronic form at http://www.aanda.org and detailed analysis are not yet possible at higher shifts (see Barazza et al 2009 for dEs in a z = 0.165 cluster). Clues to the origin of dEs may be given by the presence of weak disk features in a significant fraction of them (Jerjen et al 2000;De Rijcke et al 2003;Lisker et al 2006b), the presence of residual star formation activity in dEs outside of the densest environments (Lisker et al 2006a;Tully & Trentham 2008;Pak et al 2014) and the finding that these have significantly flatter shapes than dEs with low relative velocities in the Virgo cluster core ). Taken together, this may be regarded as supporting the hypothesis that many dEs were formed from disk galaxies that were affected and eventually transformed by a dense environment (for further observational aspects related to this hypothesis, see also Kormendy 1985;Binggeli et al 1990;De Rijcke et al 2005;Beasley et al 2006;Smith et al 2012;Ryś et al 2014).…”

Section: Introductionmentioning

confidence: 99%

On the occurrence of galaxy harassment

Bialas

Lisker

Olczak

et al. 2015

A&A

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Context. Tidal interactions of galaxies in galaxy clusters have been proposed as one potential explanation of the morphology-density relation at low masses. Earlier studies have shown that galaxy harassment is a suitable mechanism for inducing a morphological transformation from low-mass late-type disk galaxies to the abundant early-type galaxies. Aims. The efficiency of tidal transformation is expected to depend strongly on the orbit of a galaxy within the cluster halo. The orbit determines both the strength of the cluster's global tidal field and the probability of encounters with other cluster members. Here we aim to explore these dependencies. Methods. We use a combination of N-body simulation and Monte-Carlo method to study the efficiency of the transformation of late-type galaxies by tidal interactions on different orbits in a galaxy cluster. Additionally, we investigate the effect of an inclination between the disk of the infalling galaxy and its orbital plane. We compare our results to observational data to assess the possible relevance of such transformations for the existing cluster galaxy population. Results. We find that galaxies that entered a cluster from the outskirts are unlikely to be significantly transformed (stellar mass loss ≤6%). Closer to the cluster centre, tidal interactions are a more efficient mechanism (stellar mass loss up to 50%) for producing harassed galaxies. The inclination of the disk can reduce the mass loss significantly, yet it amplifies the thickening of the galaxy disk. Galaxies with smaller sizes on intermediate orbits are nearly unaffected by tidal interactions. The tidal influence on an infalling galaxy and the likelihood that it leads to galaxy harassment make a very stochastical process that depends on the galaxy's specific history. Conclusions. We conclude that harassment is a suitable mechanism that could explain the transformation of at least a fraction of galaxies inside galaxy clusters. However, the transformation would have to start at an early epoch in protocluster environments and continue until today, in order to result in a complete morphological transformation.

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The properties of early-type galaxies in the Ursa Major cluster

Cited by 35 publications

References 90 publications

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

Dwarf Galaxy Discoveries from the KMTNet Supernova Program. I. The NGC 2784 Galaxy Group^*

On the occurrence of galaxy harassment

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The properties of early-type galaxies in the Ursa Major cluster

Cited by 35 publications

References 90 publications

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

A rare example of low surface-brightness radio lobes in a gas-rich early-type galaxy: the story of NGC 3998

Dwarf Galaxy Discoveries from the KMTNet Supernova Program. I. The NGC 2784 Galaxy Group*

On the occurrence of galaxy harassment

Contact Info

Product

Resources

About

Dwarf Galaxy Discoveries from the KMTNet Supernova Program. I. The NGC 2784 Galaxy Group^*