From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies

Knierman, Karen; Gallagher, S. C.; Charlton, Jane C.; Hunsberger, S.; Whitmore, Bradley C.; Kundu, Arunav; Hibbard, J. E.; Zaritsky, Dennis

doi:10.1086/377481

Cited by 78 publications

(123 citation statements)

References 66 publications

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“…5), which Tacconi et al (1999) found to display a velocity gradient and interpreted as due to a self-gravitating gas disc located in between the nuclei, is puzzling, since from merger simulations this is generally not expected to occur. We could be seeing a collapsed gas clump in a tidal arm -such features are found to occur quite often in simulations of merging galaxies above a certain gas fraction (Wetzstein et al 2007;Bournaud et al 2008), and are also seen in observations (Knierman et al 2003). An alternative, and perhaps more likely, interpretation of this gas concentration is a tidal bridge connecting the two nuclei that is viewed in projection.…”

Section: Merger Geometry and Stage And Cold Gas Concentrationsupporting

confidence: 53%

NGC 6240: merger-induced star formation and gas dynamics

Engel

Davies

Genzel

et al. 2010

A&A

111

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We present spatially resolved integral field spectroscopic K-band data at a resolution of 0.13 (60 pc) and interferometric CO(2-1) line observations of the prototypical merging system NGC 6240. Despite the clear rotational signature, the stellar kinematics in the two nuclei are dominated by dispersion. We use Jeans modelling to derive the masses and the mass-to-light ratios of the nuclei. Combining the luminosities with the spatially resolved Brγ equivalent width shows that only 1/3 of the K-band continuum from the nuclei is associated with the most recent star forming episode; and that less than 30% of the system's bolometric luminosity and only 9% of its stellar mass is due to this starburst. The star formation properties, calculated from typical merger star formation histories, demonstrate the impact of different assumptions about the star formation history. The properties of the nuclei, and the existence of a prominent old stellar population, indicate that the nuclei are remnants of the progenitor galaxies' bulges.

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Section: Merger Geometry and Stage And Cold Gas Concentrationsupporting

confidence: 53%

NGC 6240: merger-induced star formation and gas dynamics

Engel

Davies

Genzel

et al. 2010

A&A

111

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“…Subsequent observations (Mirabel et al 1991;Hernquist 1992) and numerical simulations (Barnes & Hernquist 1992;Elmegreen et al 1993) demonstrated that the existence of dwarf galaxies as a result of a major interaction is possible. Since then and up until now, several observing campaigns have been launched in interacting systems, such as those in NGC 2782 (Yoshida et al 1994), Arp 105 (Duc & Mirabel 1994;Duc et al 1997), NGC 7252 (Hibbard et al 1994), NGC 5291 (Duc & Mirabel 1998;Higdon et al 2006), Arp 245 , small samples (Weilbacher et al 2000(Weilbacher et al , 2003Knierman et al 2003;Monreal-Ibero et al 2007), and Arp 305 (Hancock et al 2009). Hibbard & Mihos (1995) also developed a successful dynamical N-body model of NGC 7252.…”

Section: Introductionmentioning

confidence: 99%

Extranuclear Hα-emitting complexes in low-z(U)LIRGs: precursors of tidal dwarf galaxies?

Miralles-Caballero

Colina

Arribas

2012

A&A

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This paper characterizes the physical and kinematic properties of external massive star-forming regions in a sample of (U)LIRGs. We use high angular resolution ACS images from the Hubble Space Telescope (HST) in F435W (∼B) and F814W (∼I) bands, as well as Hα-line emission maps obtained with integral field spectroscopy. We find 31 external Hα-emitting (i.e., young star-forming) complexes in 11 (U)LIRGs. These complexes have in general similar sizes (from few hundreds of pc to about 2 kpc), luminosities (M F435W < -10.65 and L(Hα) > 10 39 L ), and metallicities (12 + log (O/H) ∼ 8.5-8.7) to extragalactic giant HII regions and TDG candidates found in less luminous mergers and compact groups of galaxies. We assess the mass content and the likelihood of survival as TDGs of the 22 complexes with simple structures in the HST images based on their photometric, structural, and kinematic properties. The dynamical tracers used (radius-σ and luminosity-σ diagrams) indicate that most of the complexes might be self-gravitating entities. The resistance to forces from the parent galaxy is studied by considering the tidal mass of the candidate and its relative velocity with respect to the parent galaxy. After combining the results of previous studies of TDG searches in ULIRGs a total of 9 complexes satisfy most of the applied criteria and thus show a high-medium or high likelihood of survival, their total mass likely being compatible with that of dwarf galaxies. They are defined as TDG candidates. We propose that they probably formed more often during the early phases of the interaction. Combining all data for complexes with IFS data where a significant fraction of the system is covered, we infer a TDG production rate of 0.3 candidates with the highest probabilities of survival per system for the (U)LIRGs class. This rate, though, might decrease to 0.1 after the systems in (U)LIRGs have evolved for 10 Gyr, for long-lived TDGs, which would imply that no more than 5-10% of the overall dwarf population could be of tidal origin.

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“…Majewski (1994) reinvestigated this issue and added Sextans and perhaps Phoenix to the Fornax-Leo-Sculptor alignment, which is now known as the FL 2 S 2 plane. To explain the alignments, a common origin via the disruption of larger satellites orbiting in these planes is usually invoked, with the smaller dSph's forming as tidal condensations or broken-off fragments during the dynamical interaction between our Galaxy and a massive satellite (Kroupa 1997), much like the tidal dwarfs seen in extragalactic contexts (e.g., Knierman et al 2003). The parent satellite has been proposed to be the Large Magellanic Cloud (LMC) for the Magellanic plane and Fornax for the FL 2 S 2 plane (Lynden-Bell 1982).…”

Section: Introductionmentioning

confidence: 99%

Absolute Proper Motion of the Fornax Dwarf Spheroidal Galaxy from Photographic andHubble Space TelescopeWFPC2 Data

et al. 2004

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We have measured the absolute proper motion of the Fornax dwarf spheroidal galaxy from a combination of photographic plate material and Hubble Space Telescope Wide Field Planetary Camera 2 data that provide a time baseline of up to 50 yr. The extragalactic reference frame consists of eight QSO images and 48 galaxies. The absolute proper motion is cos ¼ 0:59 AE 0:16 mas yr À1 and ¼ À0:15 AE 0:16 mas yr À1 . The corresponding orbit of Fornax is polar, with an eccentricity of 0.27 and a radial period of 4.5 Gyr. Fornax's current location is near pericenter. The direction of the motion of Fornax supports the notion that Fornax belongs to the Fornax-Leo I-Leo II-Sculptor-Sextans stream as hypothesized by both Lynden-Bell and Majewski. According to our orbit determination, Fornax crossed the Magellanic plane $190 Myr ago, a time that coincides with the termination of the star formation process in Fornax. We propose that ram pressure stripping due to the passage of Fornax through a gaseous medium denser than the typical intragalactic medium left behind from the LMC may have caused the end of star formation in Fornax. The excess, anomalous clouds within the south Galactic pole region of the Magellanic Stream, whose origin has long been debated in the literature as constituents of either the Magellanic Stream or of the extragalactic Sculptor group, are found to lie along the orbit of Fornax. We speculate that these clouds are stripped material from Fornax as the dwarf crossed the orbit of the Magellanic Clouds.

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From Globular Clusters to Tidal Dwarfs: Structure Formation in the Tidal Tails of Merging Galaxies

Cited by 78 publications

References 66 publications

NGC 6240: merger-induced star formation and gas dynamics

NGC 6240: merger-induced star formation and gas dynamics

Extranuclear Hα-emitting complexes in low-z(U)LIRGs: precursors of tidal dwarf galaxies?

Absolute Proper Motion of the Fornax Dwarf Spheroidal Galaxy from Photographic andHubble Space TelescopeWFPC2 Data

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