Dynamically Close Galaxy Pairs and Merger Rate Evolution in the CNOC2 Redshift Survey

Patton, David R.; Pritchet, C. J.; Carlberg, R. G.; Marzke, Ronald O.; Yee, H. K. C.; Hall, Patrick B.; Lin, Huan; Morris, Simon L.; Sawicki, Marcin; Shepherd, C. W.; Wirth, Gregory D.

doi:10.1086/324543

Cited by 240 publications

(346 citation statements)

References 27 publications

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“…Following Patton et al (2000Patton et al ( , 2002 and our previous work, the number of close companions per galaxy is:…”

Section: Dataset and Methodologymentioning

confidence: 99%

“…The second weight is for galaxies close (within 500 km s −1 ) to the redshift limits of each volume-limited box, and accounts for possible companions missed because they lie just beyond these boundaries. As in Patton et al (2000Patton et al ( , 2002) the value of this weight is set at 2. Similar weights need to be applied to the primary sample as well, to account for missed primaries in the same manner (recall that both primary and secondary samples are the same):…”

Section: Dataset and Methodologymentioning

confidence: 99%

“…With the availability of large redshift databases from giant redshift surveys it is now possible to identify close pairs in 3D space (position and relative velocity), such that, if bound, these galaxies will merge within the dynamical friction timescale (≈ 1 Gyr). The formalism and its application to the SSRS2 and CFRS surveys have been presented in Patton et al (2000Patton et al ( , 2002; we have used this method to measure the local pair fraction and merger rate from the Millennium Galaxy Catalogue (MGC; Liske et al 2003;Driver et al 2005) in De Propris et al ( , 2007, where we also compared the results to asymmetrybased estimates (De Propris et al 2007). Several other studies have searched for dynamically close pairs out to z ∼ 1 (e.g.…”

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confidence: 99%

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Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Propris

Baldry

Bland-Hawthorn

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We derive the close pair fractions and volume merger rates for galaxies in the GAMA survey with −23 < M r < −17 (Ω M = 0.27, Ω Λ = 0.73, H 0 = 100 km s −1 Mpc −1 ) at 0.01 < z < 0.22 (lookback time of < 2 Gyr). The merger fraction is approximately 1.5% per Gyr at all luminosities (assuming 50% of pairs merge) and the volume merger rate is ≈ 3.5 × 10 −4 Mpc −3 Gyr −1 . We examine how the merger rate varies by luminosity and morphology. Dry mergers (between red/spheroidal galaxies) are found to be uncommon and to decrease with decreasing luminosity. Fainter mergers are wet, between blue/disky galaxies. Damp mergers (one of each type) follow the average of dry and wet mergers. In the brighter luminosity bin (−23 < M r < −20) the merger rate evolution is flat, irrespective of colour or morphology, out to z ∼ 0.2. The makeup of the merging population does not appear to change over this redshift range. Galaxy growth by major mergers appears comparatively unimportant and dry mergers are unlikely to be significant in the buildup of the red sequence over the past 2 Gyr. We compare the colour, morphology, environmental density and degree of activity (BPT class) of galaxies in pairs to those of more isolated objects in the same volume. Galaxies in close pairs tend to be both redder and slightly more spheroid-dominated than the comparison sample. We suggest that this may be due to 'harassment' in multiple previous passes prior to the current close interaction. Galaxy pairs do not appear to prefer significantly denser environments. There is no evidence of an enhancement in the AGN fraction in pairs, compared to other galaxies in the same volume

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“…Following Patton et al (2000Patton et al ( , 2002 and our previous work, the number of close companions per galaxy is:…”

Section: Dataset and Methodologymentioning

confidence: 99%

Section: Dataset and Methodologymentioning

confidence: 99%

mentioning

confidence: 99%

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Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Propris

Baldry

Bland-Hawthorn

et al. 2014

Monthly Notices of the Royal Astronomical Society

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“…The 30 kpc separation employed is motivated by work which shows that star formation and AGN activity can be efficiently triggered when the separation between interacting galaxies is within 30 kpc (see e.g. Patton et al 2002;Scudder et al 2012;Scott & Kaviraj 2014). To quantify the role of merging in triggering our radio AGN, we perform an identical exercise (visual inspection + neighbours analysis) on our control sample of ETGs.…”

Section: T R I G G E R I N G O F L O C a L Ag Nmentioning

confidence: 99%

The triggering of local AGN and their role in regulating star formation

Kaviraj

Shabala

Deller

et al. 2015

Mon. Not. R. Astron. Soc.

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We explore the processes that trigger local AGN and the role of these AGN in regulating star formation, using ∼550 nearby galaxies observed by the mJy Imaging VLBA Exploration at 20 cm (mJIVE) survey. The 10 7 K brightness temperature required for an mJIVE detection cannot be achieved via star formation alone, allowing us to unambiguously detect nearby radio AGN and study their role in galaxy evolution. Radio AGN are an order of magnitude more common in early-type galaxies (ETGs) than in their late-type counterparts. The VLBI-detected ETGs in this study have a similar stellar mass distribution to their undetected counterparts, are typically not the central galaxies of clusters and exhibit merger fractions that are significantly higher than in the average ETG. This suggests that these radio AGN (which have VLBI luminosities >10 22 W Hz −1 ) are primarily fuelled by mergers, and not by internal stellar mass-loss or cooling flows. Our radio AGN are a factor of ∼3 times more likely to reside in the UV-optical red sequence than the average ETG. Furthermore, typical AGN lifetimes (a few 10 7 yr) are much shorter than the transit times from blue cloud to red sequence (∼1.5 Gyr). This indicates that nearby (merger-triggered) AGN appear several dynamical time-scales into the associated star formation episode. This implies that such AGN typically couple only to residual gas, at a point where star formation has already declined significantly, and are, therefore, unlikely to play a significant role in regulating the star formation episode.

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“…w θ is an angular incompleteness weight (see Patton et al 2000Patton et al , 2002 which we define as…”

Section: The Asymmetries Of Non-interacting Projected Pairsmentioning

confidence: 99%

Galaxy And Mass Assembly (GAMA): refining the local galaxy merger rate using morphological information

Casteels

Conselice

Bamford

et al. 2014

Monthly Notices of the Royal Astronomical Society

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We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass dependent merger fraction and merger rate using galaxy pairs and the CAS structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies, and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to M * = 10 8 M ⊙ with mass ratios of <100:1 and line of sight velocity differences of ∆V < 500 km s −1 . We find a significant increase in mean asymmetries for projected separations less than the sum of the individual galaxy's Petrosian 90 radii. For systems in major merger pairs with mass ratios of <4:1 both galaxies in the pair show a strong increase in asymmetry, while in minor merger systems (with mass ratios of >4:1) the lower mass companion becomes highly asymmetric, while the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass dependent major merger fraction is fairly constant at ∼ 1.3 − 2% between 10 9.5 < M * < 10 11.5 M ⊙ , and increases to ∼ 4% at lower masses. When the observability time scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total co-moving volume major merger rate over the range 10 8.0 < M * < 10 11.5 M ⊙ is (1.2 ± 0.5) × 10 −3 h 3 70 Mpc −3 Gyr −1 . Key words: galaxies: general -galaxies: evolution -galaxies: interactions -galaxies: statistics ⋆ E-mail: kcasteels@gmail.com (KRVC) 2 K. R. V. Casteels et al.

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Dynamically Close Galaxy Pairs and Merger Rate Evolution in the CNOC2 Redshift Survey

Cited by 240 publications

References 27 publications

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

Galaxy and Mass Assembly (GAMA): merging galaxies and their properties

The triggering of local AGN and their role in regulating star formation

Galaxy And Mass Assembly (GAMA): refining the local galaxy merger rate using morphological information

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