Galaxy pairs in the Sloan Digital Sky Survey – VIII. The observational properties of post-merger galaxies

By Sara L. Ellison, J. Trevor Mendel, David R. Patton, J. Scudder. 2013

190 citations recorded by the source corpus.

In order to investigate the effects of galaxy mergers throughout the interaction sequence, we present a study of 10,800 galaxies in close pairs and a smaller sample of 97 post-mergers identified in the Sloan Digital Sky Survey. We find that the average central star formation rate (SFR) enhancement (x 3.5) and the fraction of starbursts (20 per cent) peak in the post-merger sample. The post-mergers also show a stronger deficit in gas phase metallicity than the closest pairs, being more metal-poor than their control by -0.09 dex. Combined with the observed trends in SFR and the timescales predicted in merger simulations, we estimate that the post-mergers in our sample have undergone coalescence within the last few hundred Myr. In contrast with the incidence of star-forming galaxies, the frequency of active galactic nuclei (AGN) peaks in the post-mergers, outnumbering AGN in the control sample by a factor of 3.75. Moreover, amongst the galaxies that host an AGN, the black hole accretion rates in the closest pairs and post-mergers are higher by a factor of ~3 than AGN in the control sample. These results are consistent with a picture in which star formation is initiated early on in the encounter, with AGN activity peaking post-coalescence.

Subfields: Astronomy and Astrophysics, Atomic and Molecular Physics, and Optics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/b01e4282594cf7abe99202ba0d443e3cfa3635f8

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Atomic and Molecular Physics, and Optics

In Instrumentation

Citations in the corpus

GALAXY AND MASS ASSEMBLY (GAMA): MID-INFRARED PROPERTIES AND EMPIRICAL RELATIONS FROM WISE (2014, result): “Although initially counter-intuitive, and contrary to studies of local galaxy pairs compared to field control samples (see, for example, Ellison et al. 2013), it should be noted that ∼40% of GAMA galaxies reside within a group, with numerous mechanisms at play.”
Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey (2017, background): “Indeed, the fraction of AGN is seen to fall dramatically at large projected separations (e.g., Ellison et al. 2013; Satyapal et al. 2014a; Ricci et al. 2017).”
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): “…interested readers to other publications from our group (Ellison et al. 2008, Ellison et al. 2011, Scudder et al. 2012, Patton et al. 2013, and Ellison et al. 2013) as well as other references (Darg et al. 2010, Silverman et al. 2011, Hung et al. 2013, Robotham et al. 2013) which together…”
Growth and activity of black holes in galaxy mergers with varying mass ratios (2014, background): “Ellison et al. (2011), Silverman et al. (2011) and Ellison et al. (2013) study the enhancement in the AGN fraction for galaxies in pairs with respect to isolated galaxies.”
Galaxy pairs in the Sloan Digital Sky Survey – IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer (2014, methodology): “The sample of visually classified post-mergers is initiallydrawn from the Galaxy Zoo (Lintott et al. 2008) catalogue presented by Darg et al. (2010), with further visual inspection and refinement by Ellison et al. (2013).”
Morphologies of z ∼ 0.7 AGN host galaxies in CANDELS: no trend of merger incidence with AGN luminosity (2014, background): “This agrees with the findings of Ellison et al. (2013) that the AGN fraction is increased by a factor of almost 4 in post-merger systems when compared to control.”