Galaxy pairs in the Sloan Digital Sky Survey – II. The effect of environment on interactions

By Sara L. Ellison, David R. Patton, L. Simard, A. McConnachie, I. Baldry, J. Trevor Mendel. 2010

143 citations recorded by the source corpus.

We use a sample of close galaxy pairs selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) to investigate in what environments galaxy mergers occur and how the results of these mergers depend on differences in local galaxy density. The galaxies are quantified morphologically using two-dimensional bulge-plus-disc decompositions and compared to a control sample matched in stellar mass, redshift and local projected density. Lower density environments have fractionally more galaxy pairs with small projected separations (r p ) and relative velocities (Δυ), but even high-density environments contain significant populations of pairs with parameters that should be conducive to interactions. The connection between environment and Δυ also implies that the velocity selection of a pairs sample affects (biases) the environment from which the pairs are selected. Metrics of asymmetry and colour are used to identify merger activity and triggered star formation. The location of star formation is inferred by distinguishing bulge and disc colours and calculating bulge fractions from the SDSS images. Galaxies in the lowest density environments show the largest changes in star formation rate, asymmetry and bulge-to-total fractions at small separations, accompanied by bluer bulge colours. At the highest local densities, the only galaxy property to show an enhancement in the closest pairs is asymmetry. We interpret these results as evidence that whilst interactions (leading to tidal distortions) occur at all densities, triggered star formation is seen only in low-to-intermediate density environments. We suggest that this is likely due to the typically higher gas fractions of galaxies in low-density environments. Finally, by cross-correlating our sample of galaxy pairs with a cluster catalogue, we investigate the dependence of interactions on clustercentric distance. It is found that for close pairs the fraction of asymmetric galaxies is highest in the cluster centres.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c404708f8d4be826c14395753cdbf3975bc7c53b

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Citations in the corpus

The impact of gas inflows on star formation rates and metallicities in barred galaxies (2011, background): “…& Kenyon 2000; Lambas et al. 2003; Alonso et al. 2004; Nikolic, Cullen & Alexander 2004; Ellison et al. 2008a), with a clear tendency for the triggered star formation to be located in the galactic centres (Barton et al. 2000; Kewley, Geller & Barton 2006; Ellison et al. 2010; Patton et al. 2011).”
Bulge mass is king: the dominant role of the bulge in determining the fraction of passive galaxies in the Sloan Digital Sky Survey (2014, background): “Closer (interacting) pairs are found to provoke enhanced star formation (Ellison et al. 2008,2010, Scudder et al. 2012, Patton et al. 2013), and the final coalescence of galaxies at the end of the merger sequence leads initially to the highest enhancements in star formation (e.g. Ellison et al.…”
Galaxy pairs in the Sloan Digital Sky Survey - IV: Interactions trigger AGN (2011, background): “…Geller & Kenyon 2000; Lambas et al 2003; Alonso et al. 2004; Nikolic, Cullen & Alexander 2004; Woods, Geller & Barton 2006; Woods & Geller 2007; Ellison et al. 2008, 2010; Patton et al. 2011; Liu et al. 2011b) and evidence for gas inflows, as indicated byiluted interstellar medium…”
Galaxy pairs in the Sloan Digital Sky Survey – VI. The orbital extent of enhanced star formation in interacting galaxies (2013, methodology): “One method of dealing with this issue is to match paired and control galaxies on local density (Ellison et al. 2010; Scudder et al. 2012).”
THEORETICAL EVOLUTION OF OPTICAL STRONG LINES ACROSS COSMIC TIME (2013, background): “For example, interacting or merging galaxies typically have lower central metallicities due to large-scale gas infall (Kewley et al. 2006a, 2010; Rupke et al. 2010b; Ellison et al. 2010; Rich et al. 2012; Scudder et al. 2012).”
Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies (2013, methodology): “…either close spectroscopic pairs, or morphologically classified mergers have been used to investigate the impact of galaxy interactions on colours (Ellison et al. 2010; Patton et al. 2011; Alonso et al. 2012; Lambas et al. 2012), star formation rates (Nikolic, Cullen & Alexander 2004; Alonso et…”
A CATALOG OF BULGE+DISK DECOMPOSITIONS AND UPDATED PHOTOMETRY FOR 1.12 MILLION GALAXIES IN THE SLOAN DIGITAL SKY SURVEY (2011, methodology): “This catalog has already been used to study visual versus quantitative morphologies (Cheng et al. 2010), galaxy pairs (Ellison et al. 2008, 2010; Patton et al. 2011), disk scaling relations at low and high redshift (Dutton et al. 2011a,b), the disk size function (Kanwar et al. 2008, and Simard…”
Galaxy pairs in the Sloan Digital Sky Survey – V. Tracing changes in star formation rate and metallicity out to separations of 80 kpc (2012, background): “…Di Matteo et al. 2007; Montuori et al. 2010; Torrey et al. 2012) and observational works (e.g., Larson & Tinsley 1978; Donzelli & Pastoriza 1997; Barton et al. 2000; Lambas et al. 2003; Alonso et al. 2004, 2006; Woods & Geller 2007; Ellison et al. 2008b, 2010; Darg et al. 2010; Xu et al. 2010).”