The Metamorphosis of Tidally Stirred Dwarf Galaxies

By Lucio Mayer, Fabio Governato, M. Colpi, B. Moore, Thomas R. Quinn, James Wadsley, Joachim Stadel, George Lake. 2001

314 citations recorded by the source corpus.

We present results from high-resolution N-body/SPH (smoothed particle hydrodynamic) simulations of rotationally supported dwarf irregular galaxies moving on bound orbits in the massive dark matter halo of the Milky Way. The dwarf models span a range in disk surface density and the masses and sizes of their dark halos are consistent with the predictions of cold dark matter cosmogonies. We show that the strong tidal field of the Milky Way determines severe mass loss in their halos and disks and induces bar and bending instabilities that transform low surface brightness dwarfs (LSBs) into dwarf spheroidals (dSphs) and high surface brightness dwarfs (HSBs) into dwarf ellipticals (dEs) in less than 10 Gyr. The final central velocity dispersions of the remnants are in the range 8-30 km s-1 and their final v/σ falls to values less than 0.5, matching well the kinematics of early-type dwarfs. The transformation requires the orbital time of the dwarf to be ≲3-4 Gyr, which implies a halo as massive and extended as predicted by hierarchical models of galaxy formation to explain the origin of even the farthest dSph satellites of the Milky Way, Leo I, and Leo II. We show that only dwarfs with central dark matter densities as high as those of Draco and Ursa Minor can survive for 10 Gyr in the proximity of the Milky Way. A correlation between the central density and the distance of the dwarfs from the primary galaxy is indeed expected in hierarchical models, in which the densest objects should have small orbital times because of their early formation epochs. Part of the gas is stripped and part is funneled to the center because of the bar, generating one strong burst of star formation in HSBs and smaller, multiple bursts in LSBs. Therefore, the large variety of star formation histories observed in Local Group dSphs arises because different types of dIrr progenitors respond differently to the external perturbation of the Milky Way. Our evolutionary model naturally explains the morphology-density relation observed in the Local Group and in other nearby loose groups. Extended low surface brightness stellar and gaseous streams originate from LSBs and follow the orbit of the dwarfs for several gigayears. Because of their high velocities, unbound stars projected along the line of sight can lead to overestimating the mass-to-light ratio of the bound remnant by a factor ≲2, but this does not eliminate the need of extremely high dark matter contents in some of the dSphs.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/21ed7305b79b0bbfcfd59c56658695ff5938f5a5

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Citations in the corpus

Formation and Evolution of Galaxy Dark Matter Halos and Their Substructure (2007, background): “All halos except one undergo pericenter passages that can lead to tidally induced changes in galaxy morphologies (Mayer et al. 2001a,b).”
THE ACS NEARBY GALAXY SURVEY TREASURY. VIII. THE GLOBAL STAR FORMATION HISTORIES OF 60 DWARF GALAXIES IN THE LOCAL VOLUME (2011, background): “Instead, Mayer et al. (2001a, 2006) advocate a more complex approach in which a combination of ram pressure stripping and stellar mass loss due to tidal effects provide a plausible model, ‘tidal stirring’, for the transformation of gas-rich dIs into gas-poor dSphs.”
FORTY-SEVEN MILKY WAY-SIZED, EXTREMELY DIFFUSE GALAXIES IN THE COMA CLUSTER (2014, background): “It seems unlikely that they are the product of galaxy harrassment (Moore et al. 1996) or tidal stirring (Mayer et al. 2001) of infalling galaxies: these processes tend toshrink galaxies, as the stars at larger radii are less bound than the stars at small radii (see, e.g., Mayer et al. 2001).”
Ultradiffuse galaxies: the high-spin tail of the abundant dwarf galaxy population (2016, background): “…the observed UDGs are incompatible with them being a population of disks, and their transformation from very extended disks to thin spheroids may well be caused by the interaction with the cluster, through ram pressure stripping and tidal stirring (e.g., Mayer et al. 2001; Kazantzidis et al. 2011).”
The Kinematic Status and Mass Content of the Sculptor Dwarf Spheroidal Galaxy (2008, background): “The presence of rotation in dSphs could support scenarios in which the progenitors of these objects were rotationally supported, disky systems, tidally stirred by the interaction with the MW (e.g. Mayer et al. 2001).”
Dark matter cores and cusps: the case of multiple stellar populations in dwarf spheroidals (2011, methodology): “This idea is supported by the universal flatness of the velocity dispersion profiles of the dSphs at least close to the centres (Evans, An, Walker 2009), as well as numerical simulations of tidal stirring of dSphs (Mayer et al. 2001).”
The stellar halo of the Galaxy (2008, background): “Such strong tides could give rise to a halo-like component (Mayer et al. 2001).”
The Tumultuous Lives of Galactic Dwarfs and the Missing Satellites Problem (2004, background): “Therefore, our results support the scenario that spheroidal systems form via strong tidal heating (Mayer et al. 2001b,a).”
A UNIVERSAL MASS PROFILE FOR DWARF SPHEROIDAL GALAXIES? (2009, methodology): “While Klimentowski et al. (2007) succesfully test their algorithm and mass estimator using an N-body simulation of a tidally “stirred” (Mayer et al. 2001a,b) satellite in which mass actually does follow light (after 99% of the initial dark mass is stripped), they do not demonstrate that their…”
Cusp-core transformations in dwarf galaxies: observational predictions (2012, background): “Galactic mergers (e.g. Searle & Zinn 1978; Read, Pontzen & Viel 2006b) and collisionless heating from a strong tidal field (e.g. Mayer et al. 2001; Lokas, Kazantzidis & Mayer 2011) both lead to stellar distributions with low v/σ .”
Galaxy formation theory (2010, background): “The generic results of such heating are to cause the galaxy to expand and to destroy cold, ordered structures such as disks (Mooreet al. 1996b, 1998; Mayer et al. 2001a,b; Gnedin 2003; Mastropietro et al. 2005a,b).”
A BARYONIC SOLUTION TO THE MISSING SATELLITES PROBLEM (2012, background): “…2001; D’Onghia et al. 2010a), and will lead to even faster disruption of a subhalo.9 Tidal heating of subhalos should also occur (Gnedin et al. 1999; Mayer et al. 2001; D’Onghia et al. 2010b; Kazantzidis et al. 2011), but requires very high resolution to capture (Choi et al. 2009) and is unlikely…”
Dynamical Evolution of Galaxies in Clusters (2003, background): “On a scale of the Local Group, Mayer et al. (2001) find that the observed dwarf spheroidal galaxies could be the remnants of tidally-disrupted LSB progenitors.”
The effects of photoionization on galaxy formation – I. Model and results at z=0 (2001, background): “Numerical simulations of satellites undergoing tidal interactions (e.g. Mayer et al. 2001) demonstrate that satellite mass profiles are affected by tidal interactions.”
The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run? (2007, methodology): “This behavior is reflected in some of the models of Mayer et al. (2001a, 2001b, 2006) although these authors did not explore orbits quite as eccentric as we are considering for Leo I.”
THE NATURE OF STARBURSTS. I. THE STAR FORMATION HISTORIES OF EIGHTEEN NEARBY STARBURST DWARF GALAXIES (2010, background): “It is unclear whether most dwarf galaxies experience starbursts during their evolution or whether only a subgroup of dwarf galaxies exhibit bursts (e.g., Marlowe et al. 1997; Mayer et al. 2001; van Zee et al. 2001b; Pasetto et al. 2003).”
The importance of tides for the Local Group dwarf spheroidals (2005, methodology): “We argue in this paper that the Local Group dSphs have not been significantly stripped interior to 1 kpc, but this need not invalidate the tidal transformation model proposed by Mayer et al. (2001a).”
THE SPLASH SURVEY: SPECTROSCOPY OF 15 M31 DWARF SPHEROIDAL SATELLITE GALAXIES (2011, background): “…in the scaling relations serves to lend further weight to this idea, and supports the notion that environment leaves an observable mark on the structural properties of satellites even in low-density groups like the LG (e.g., Mayer et al. 2001; Kazantzidis et al. 2011; Tollerud et al. 2011a).”
The DART Imaging And CaT Survey of the Fornax Dwarf Spheroidal Galaxy (2006, background): “The importance of these eff cts depends strongly on the orbital parameters of the satellite, th apocenter-to-pericenter ratio, and the time at which the sat llite enters the Milky Way potential.”
The Dark Matter Crisis: Falsification of the Current Standard Model of Cosmology (2012, background): “Satellite galaxies are, to a large extend, of the gas-poor type, which is naturally understood as a result of gas being stripped from initial gaseous dIrr-type satellite galaxies (Mayer et al. 2001).”