Quantified H i morphology - III. Merger visibility times from H i in galaxy simulations

Holwerda, Benne W.; Pirzkal, Norbert; Cox, Thomas J.; Blok, W. J. G. de; Weniger, J.; Bouchard, Antoine; Blyth, S. L.; Heyden, K. J. van der

doi:10.1111/j.1365-2966.2011.18940.x

Cited by 44 publications

(84 citation statements)

References 32 publications

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“…But for S > 0.3 the tail dissipation time-scale may extend to ∼1 Gyr and in this case the tail may fragment to form TDGs (Barnes 1992;Oh et al 2008). However four pieces of evidence support an interaction within the times-cales derived from the Oh et al (2008) models: (i) H i morphological perturbation signatures from a full merger of galaxies with total baryonic masses of the same order as NGC 90, only remain identifiable for a maximum of ∼4 × 10 8 yr to 7 × 10 8 yr (Holwerda et al 2011 • counter-clockwise from a line joining the optical centres of NGC 90 and NGC 93. If we assume that the NGC 90/NGC 93 bridge formed along an axis joining the two galaxies soon after their closest approach, as interaction models predict, then the current ∼60…”

Section: Evidence Of An Interaction Between Ngc 90 and Ngc 93mentioning

confidence: 99%

Arp 65 interaction debris: massive H I displacement and star formation

Sengupta

Scott

Paudel

et al. 2015

A&A

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Context. Pre-merger tidal interactions between pairs of galaxies are known to induce significant changes in the morphologies and kinematics of the stellar and interstellar medium components. Large amounts of gas and stars are often found to be disturbed or displaced as tidal debris. This debris then evolves, sometimes forming stars and occasionally forming tidal dwarf galaxies. Here we present results from our H i study of Arp 65, an interacting pair hosting extended H i tidal debris.Aims. In an effort to understand the evolution of tidal debris produced by interacting pairs of galaxies, including in situ star and tidal dwarf galaxy formation, we are mapping H i in a sample of interacting galaxy pairs. The Arp 65 pair is the latest member of this sample to be mapped. Methods.Our resolved H i 21 cm line survey is being carried out using the Giant Metrewave Radio Telescope. We used our H i survey data as well as available SDSS optical, Spitzer infra-red and GALEX UV data to study the evolution of the tidal debris and the correlation of H i with the star-forming regions within it.Results. In Arp 65 we see a high impact pre-merger tidal interaction involving a pair of massive galaxies (NGC 90 and NGC 93) that have a stellar mass ratio of ∼1:3. The interaction, which probably occurred ∼1.0-2.5 × 10 8 yr ago, appears to have displaced a large fraction of the H i in NGC 90 (including the highest column density H i) beyond its optical disk. We also find extended on-going star formation in the outer disk of NGC 90. In the major star-forming regions, we find the H i column densities to be ∼4.7 × 10 20 cm −2 or lower. But no signature of star formation was found in the highest column density H i debris SE of NGC 90. This indicates conditions within the highest density H i debris remain hostile to star formation and it reaffirms that high H i column densities may be a necessary but not sufficient criterion for star formation.

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Section: Evidence Of An Interaction Between Ngc 90 and Ngc 93mentioning

confidence: 99%

Arp 65 interaction debris: massive H I displacement and star formation

Sengupta

Scott

Paudel

et al. 2015

A&A

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“…As an example, they are used for galaxy morphology classification in the analysis of the HST and SDSS galaxy surveys (Abraham et al 2003;Conselice 2003;Lotz et al 2004;Zamojski et al 2007;Holwerda et al 2011a;Wang et al 2012). Abraham et al (2003), Lotz et al (2004), andWang et al (2012) also revealed the inter-relation between Gini, concentration and M 20 , as well as the possible inter-change between the concentration and Gini parameter for high-z galaxies.…”

Section: Introduction Of Morphology Parametersmentioning

confidence: 99%

“…The combination of morphology parameters has been successfully used to classify different galaxy morphologies (Zamojski et al 2007;Scarlata et al 2007;Holwerda et al 2011a), so we want to investigate their usefulness in galaxy cluster classification. Our focus is not limited to separating galaxy clusters into relaxed and non-relaxed categories, but to study correlations between X-ray gas properties and morphology parameters, as well as the evolution of morphological properties of galaxy clusters from the high redshift universe up to the present.…”

Section: Introductionmentioning

confidence: 99%

Morphology parameters: substructure identification in X-ray galaxy clusters

Parekh

Heyden

Ferrari

et al. 2015

A&A

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Context. In recent years multi-wavelength observations have shown the presence of substructures related to merging events in a large proportion of galaxy clusters. Clusters can be roughly grouped into two categories -relaxed and non-relaxed -and a proper characterisation of the dynamical state of these systems is crucial for both astrophysical and cosmological studies. Aims. In this paper we investigate the use of a number of morphological parameters (Gini, M 20 , concentration, asymmetry, smoothness, ellipticity, and Gini of the second-order moment, G M ) introduced to automatically classify clusters as relaxed or dynamically disturbed systems. Methods. We apply our method to a sample of clusters at different redshifts extracted from the Chandra archive and investigate possible correlations between morphological parameters and other X-ray gas properties. Results. We conclude that a combination of the adopted parameters is a very useful tool for properly characterising the X-ray cluster morphology. According to our results, three parameters -Gini, M 20 , and concentration -are very promising for identifying cluster mergers. The Gini coefficient is a particularly powerful tool, especially at high redshift, because it is independent of the choice of the position of the cluster centre. We find that high Gini (>0.65), high concentration (>1.55), and low M 20 (<-2.0) values are associated with relaxed clusters, while low Gini (<0.4), low concentration (<1.0), and high M 20 (>-1.4) characterise dynamically perturbed systems. We also estimate the X-ray cluster morphological parameters in the case of radio loud clusters. Since they are in excellent agreement with previous analyses we confirm that diffuse intracluster radio sources are associated with major mergers.

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“…Gasrich ellipticals, which may be merger remnants, sometimes exhibit large HI masses distributed in extended structures, but with surface densities that are insufficient to form new stars (Oosterloo et al 2007b). Indeed, it has been suggested that the long lifetimes of such extended HI structures, which may have no (or very low surface brightness) optical counterparts (Hibbard & Yun 1999;Buyle et al 2008) may be an effective way of identifying mergers long after optical disturbances have faded (Hibbard & van Gorkom 1996;Holwerda et al 2011;Lelli, Verheijen & Fraternali 2014).…”

Section: Introductionmentioning

confidence: 99%

The neutral gas content of post-merger galaxies

Ellison

Fertig

Rosenberg

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Measurements of the neutral hydrogen gas content of a sample of 93 post-merger galaxies are presented, from a combination of matches to the ALFALFA.40 data release and new Arecibo observations. By imposing completeness thresholds identical to that of the ALFALFA survey, and by compiling a mass-, redshift-and environment-matched control sample from the public ALFALFA.40 data release, we calculate gas fraction offsets (∆f gas ) for the post-mergers, relative to the control sample. We find that the post-mergers have HI gas fractions that are consistent with undisturbed galaxies. However, due to the relative gas richness of the ALFALFA.40 sample, from which we draw our control sample, our measurements of gas fraction enhancements are likely to be conservative lower limits. Combined with comparable gas fraction measurements by Fertig et al. in a sample of galaxy pairs, who also determine gas fraction offsets consistent with zero, we conclude that there is no evidence for significant neutral gas consumption throughout the merger sequence. From a suite of 75 binary merger simulations we confirm that star formation is expected to decrease the post-merger gas fraction by only 0.06 dex, even several Gyr after the merger. Moreover, in addition to the lack of evidence for gas consumption from gas fraction offsets, the observed HI detection fraction in the complete sample of post-mergers is twice as high as the controls, which suggests that the post-merger gas fractions may actually be enhanced. We demonstrate that a gas fraction enhancement in post-mergers, relative to a stellar mass-matched control sample, would indeed be the natural result of merging randomly drawn pairs from a parent population which exhibits a declining gas fraction with increasing stellar mass.

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Quantified H i morphology - III. Merger visibility times from H i in galaxy simulations

Cited by 44 publications

References 32 publications

Arp 65 interaction debris: massive H I displacement and star formation

Arp 65 interaction debris: massive H I displacement and star formation

Morphology parameters: substructure identification in X-ray galaxy clusters

The neutral gas content of post-merger galaxies

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