Galaxy merging, the fundamental plane of elliptical galaxies and the MBH --  0 relation

Abstract

We explore the effects of dissipationless merging on the fundamental plane of elliptical galaxies using an N-body code based on a new, high-performance numerical scheme. We investigate the two extreme cases of galaxy growth by equal-mass merging and accretion of small stellar systems; in a subset of simulations we also consider the presence of dark matter haloes around the merging galaxies. Curiously, we found that the fundamental plane is preserved by major merging, while in the accretion scenario its edge-on thickness is only marginally reproduced, with substantial thickening in the case of merging with low angular momentum. We also found that both the Faber-Jackson and Kormendy relations are not reproduced by the simulations, in accordance with the results of a preliminary analysis based on a simple application of the virial theorem. Finally, we discuss the implications of our results for the origin of the M BH -σ 0 and Magorrian relations. We found that dissipationless merging is unable to reproduce the M BH -σ 0 relation, if the black hole masses add linearly (while the Magorrian relation is nicely reproduced); in contrast, a black hole merging with substantial emission of gravitational waves reproduces the M BH -σ 0 relation but fails to reproduce the Magorrian relation. We argue that our results strongly point towards a major role of dissipation in the formation of early-type galaxies and in the growth of their central supermassive black holes, thus supporting the idea of a link between galaxy formation and quasi-stellar object activity.

Mergers and Mass Accretion Rates in Galaxy Assembly: The Millennium Simulation Compared to Observations ofz≈ 2 Galaxies

“…Tacconi et al (2008) show (in their Fig. 5) that this requires that the SMG masses grow by about an order of magnitude by z ¼ 0, assuming dry mergers with structurally similar systems, following Nipoti et al (2003). We find that of the halos we have identified with the SMGs in x 3.2, %70% remain main branch halos to z ¼ 0 ( Fig.…”

A Survey of Merger Remnants. III. Are Merger Remnants Supported by Rotation or Anisotropy?

“…Other mechanisms, such as dissipationless mergers of bulge-dominated galaxies ) may be able to better reproduce the elliptical galaxies with the smallest (V/ ) Ã and most negativeā 4 /a parameters. However, this does raise a host of other problems, including reproducing the fundamental plane and M BH -0 relations (e.g., Nipoti et al 2003;Kazantzidis et al 2005), as well as the presence of intermediate-age stellar populations and globular clusters in elliptical galaxies (e.g., Schweizer et al 1990;Whitmore et al 1997Whitmore et al , 2002Rejkuba et al 2001;Thomas et al 2004;Goudfrooij et al 2004;Trager et al 2005). Moreover, with recent deep surveys indicating the presence of a red sequence in color-magnitude diagrams of galaxies as far back as z $ 1 (Hogg et al 2004;Bell et al 2004;McIntosh et al 2005), new questions have been raised concerning the limitations of disk-disk mergers versus other mechanisms, including dissipationless mergers between bulge-dominated galaxies.…”

Can Minor Merging Account for the Size Growth of Quiescent Galaxies? New Results From the Candels Survey

“…It has been extensively studied, particularly at high redshift where it is the most observationally accessible projection (e.g., Trujillo et al 2006Trujillo et al , 2007Toft et al 2007Toft et al , 2009Zirm et al 2007;Buitrago et al 2008;Cimatti et al 2008;van der Wel et al 2008;Damjanov et al 2009Damjanov et al , 2011Mancini et al 2010;Ryan et al 2010;Saracco et al 2011). The mass-size plane provides some of the most powerful constraints on the merger histories of galaxies (e.g., Nipoti et al 2003), which we exploit in Section 5.…”

“…The growth efficiency is commonly parameterized by α = d log R h /d log M * . For 1 : 1 mergers of spheroids, both the mass and radius approximately double and α 1 (e.g., Hernquist et al 1993;Nipoti et al 2003;Boylan-Kolchin et al 2006).…”