High-luminosity IRAS galaxies – I. The proportion of IRAS galaxies in interacting systems

Lawrence, Andy; Rowan‐Robinson, M.; Leech, K.; Jones, D. H. P.; Wall, J. V.

doi:10.1093/mnras/240.2.329

Cited by 67 publications

(59 citation statements)

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“…The current paradigm suggests that they are the result of numerous mergers between smaller galaxies (e.g., White & Rees 1978;Cole et al 2000). When the masses of two colliding galaxies are similar, such major mergers often result in a young starburst that easily outshines the underlying majority of old stellar populations (Lawrence et al 1989) and sometimes even changes the morphology of galaxies (e.g., Arp 1966;Toomre & Toomre 1972). In this respect, understanding the frequency of mergers and their impact on galaxy evolution is the key to an accurate reconstruction of the apparently complex history of massive galaxy formation.…”

Section: Introductionmentioning

confidence: 99%

Merger relics of cluster galaxies

Lee

Jung

et al. 2013

A&A

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Context. Sheen and collaborators recently found that a surprisingly large portion (38%) of massive early-type galaxies in heavy clusters show strong merger-related disturbed features. This contradicts the general understanding that massive clusters are hostile environments for galaxy mergers. Considering the significance of mergers in galaxy evolution, it is important to understand this. Aims. We aim to present a theoretical foundation that explains galaxy mergers in massive clusters. Methods. We used the N-body simulation technique to perform a cosmological-volume simulation and derive dark-halo merger trees. Then, we used the semi-analytic modeling technique to populate each halo with galaxies. We ran hydrodynamic simulations of galaxy mergers to estimate the lifetime of merger features for the imaging condition used by Sheen and collaborators. We applied this merger feature lifetime to our semi-analytic models. Finally, we counted the massive early-type galaxies in heavy model clusters that would show strong merger features. Results. While there still are substantial uncertainties, our preliminary results are remarkably close to the observed fraction of galaxies with merger features. Key ingredients for the success are twofold: firstly, the subhalo motion in dark haloes has been accurately traced, and, second, the lifetime of merger features has been properly estimated. As a result, merger features are expected to last very long in cluster environments. Many massive early-type galaxies in heavy clusters therefore show merger features not because they experience mergers in the current clusters in situ, but because they still carry their merger features from their previous halo environments. Conclusions. Investigating the merger relics of cluster galaxies is potentially important, because it uniquely allows us to backtrack the halo merger history.

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Section: Introductionmentioning

confidence: 99%

Merger relics of cluster galaxies

Lee

Jung

et al. 2013

A&A

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“…A smaller but systematic enhancement compared to isolated spirals is also seen in the disk radio power (Hummel 1981) and disk Hα emission (Kennicutt et al 1987) which is again attributed to interaction induced starformation activity. Additionally, the fraction of interacting systems found in IRAS-selected samples increases with FIR luminosity (Lawrence 1989;Gallimore & Keel 1993), suggesting that collisions play a major role in triggering powerful starbursts.…”

Section: Introductionmentioning

confidence: 99%

Cold gas and star formation in a merging galaxy sequence

Georgakakis

Forbes

Norris³

2000

Monthly Notices RAS

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We explore the evolution of the cold gas (molecular and neutral hydrogen) and starformation activity during galaxy interactions, using a merging galaxy sequence comprising both pre-and post-merger candidates. Data for this study come from the literature but supplemented by some new radio observations presented here. Firstly, we confirm that the ratio of far-infrared luminosity to molecular hydrogen mass (L F IR /M (H 2 ); star-formation efficiency) increases close to nuclear coalescence. After the merging of the two nuclei there is evidence that the star-formation efficiency declines again to values typical of ellipticals. This trend can be attributed to M (H 2 ) depletion due to interaction induced star-formation. However, there is significant scatter, likely to arise from differences in the interaction details (e.g. disk-to-bulge ratio, geometry) of individual systems. Secondly, we find that the central molecular hydrogen surface density, Σ H2 , increases close to the final stages of the merging of the two nuclei. Such a trend, indicating gas inflows due to gravitational instabilities during the interaction, is also predicted by numerical simulations. Furthermore, there is evidence for a decreasing fraction of cold gas mass from early interacting systems to merger remnants, attributed to neutral hydrogen conversion into other forms (e.g. stars, hot gas) and molecular hydrogen depletion due to on-going star-formation. The evolution of the total-radio to blue-band luminosity ratio, reflecting the total (disk and nucleus) star-formation activity, is also investigated. Although this ratio is on average higher than that of isolated spirals, we find a marginal increase along the merging sequence, attributed to the relative insensitivity of disk star-formation to interactions. However, a similar result is also obtained for the nuclear radio emission, although galaxy interactions are believed to significantly affect the activity (star-formation, AGN) in the central galaxy regions. Nevertheless, the nuclear-radio to blue-band luminosity ratio is significantly elevated compared to isolated spirals. Finally, we find that the FIR-radio flux ratio distribution of interacting galaxies is consistent with star-formation being the main energising source.

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“…Armus, Heckman, andMiley 1987,1990;Fairclough 1986;Lawrence et al 1989;Sanders et al 1988a). Such samples are easily generated, but suffer from some ambiguity of interpretation (as noted above, there is still some controversy about what fraction of far-IR-luminous galaxies are indeed powered by nuclear starbursts vs. a "buried QSO" or even vs. an unusually heavily obscured "normal" stellar population).…”

Section: Evidence Linking Interactions T O Nuclear Activity a Inmentioning

confidence: 99%

“…This is not significantly different from the fraction of morphologically peculiar galaxies in randomly-selected samples of field galaxies (cf. Lawrence et al 1989;Armus, Heckman, and Miley 1987). It is important to realize that this luminosity range brackets the "knee" in the IR luminosity function of galaxies: thus, the galaxies that dominate IR-flux-limited samples do not have a strongly abnormal incidence rate of peculiar optical morphologies.…”

Section: Evidence Linking Interactions T O Nuclear Activity a Inmentioning

confidence: 99%

“…No one has yet made a rigorous effort to compare the fraction of "disturbed/interacting" QSO hosts to any realistic comparison sample of non-active galaxies (recall that the number of near-neighbors around low-z QSO's may or may not be unusually large, depending on the Hubble type of the QSO host). For example, Lawrence et al (1989) found that about 18% of optically-selected "field" galaxies with redshifts comparable to those of low-z QSO's were classified by them as morphologically peculiar. While this fraction is significantly smaller than the fractions of "peculiar" QSO hosts quoted above, it is slightly worrying that the morphological classifications of the QSO and field galaxies were not made by the same people using the same data.…”

Section: H) Morphology Of Qso Host Galaxiesmentioning

confidence: 99%

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Galaxy Interactions and the Stimulation of Nuclear Activity

Heckman

1990

International Astronomical Union Colloquium

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The idea that interactions between galaxies can lead to enhanced galactic activity has a long and noble lineage. Since the early days of Baade and Minkowski (1954), through the seminal paper of Toomre and Toomre (1977) with its “stoking the furnace” imagery, to the similarly colorful and influential “feeding the monster” paper of Gunn (1979), and the landmark work by Larson and Tinsley (1978), this idea was elaborated upon and generalized. The pace of development of this hypothesis has accelerated greatly on both the observational and theoretical fronts during the 1980’s, due in part to a growing perception that the AGN phenomenon could only be understood when the role of the environment in triggering or nurturing the activity was understood (cf. Balick and Heckman 1982). In recent years, the impact of the extragalactic IRAS database (on the observational side) and of the new generation of supercomputers and innovative software (on the numerical side) have led to an almost explosive growth in the number of papers written about this subject.

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High-luminosity IRAS galaxies – I. The proportion of IRAS galaxies in interacting systems

Cited by 67 publications

References 0 publications

Merger relics of cluster galaxies

Merger relics of cluster galaxies

Cold gas and star formation in a merging galaxy sequence

Galaxy Interactions and the Stimulation of Nuclear Activity

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