The DART Imaging And CaT Survey of the Fornax Dwarf Spheroidal Galaxy

By G. Battaglia, E. Tolstoy, A. Helmi, M. Irwin, B. Letarte, P. Jablonka, V. Hill, K. Venn, M. Shetrone, N. Arimoto and 6 more. 2006

258 citations recorded by the source corpus.

Aims. As part of the DART project we have used the ESO ESO/2.2m Wide Field Imager in conjunction with the VLT/FLAMES(star star) GIRAFFE spectrograph to study the detailed properties of the resolved stellar population of the Fornax dwarf spheroidal galaxy out to and beyond its tidal radius. Fornax dwarf spheroidal galaxy has had a complicated evolution and contains significant numbers of young, intermediate age and old stars. We investigate the relation between these different components by studying their photometric, kinematic and abundance distributions. Methods. We re-derived the structural parameters of the Fornax dwarf spheroidal using our wide field imaging covering the galaxy out to its tidal radius, and analysed the spatial distribution of the Fornax stars of different ages as selected from colour-magnitude diagram analysis. We have obtained accurate velocities and metetallicities from spectra in the Ca II triplet wavelength region for 562 Red Giant Branch stars which have velocities consistent with membership of the Fornax dwarf spheroidal. Results. We have found evidence for the presence of at least three distinct stellar components: a young population ( few 100 Myr old) concentrated in the centre of the galaxy, visible as a Main Sequence in the colour-magnitude diagram; an intermediate age population ( 2-8 Gyr old); and an ancient population ( (> 10 Gyr), which are distinguish distinguishable from each other kinematically, from the metallicity, distribution and in the spatial distribution of stars found in the colour-magnitude diagram. Conclusions. From our spectroscopic analysis we find that the "metal rich" stars ([Fe/H] > -1.3) show a less extended and more concentrated spatial distribution, and display colder kinematics than the "metal poor" stars ([Fe/H] <-1.3). There is tentative evidence that the ancient stellar population in the centre of Fornax does not exhibit equilibrium kinematics. This could be a sign of a relatively recent accretion of external material, such as the mer merger of another galaxy or other means of gas accretion at some point in the fairly recent past, consistent with other recent evidence of substructure ( Coleman et al. 2004, AJ, 127, 832; 2005, AJ, 129, 1443).

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

The star formation and chemical evolution history of the Fornax dwarf spheroidal galaxy (2012, methodology): “The results are consistent with previous determinations of the AMR (Pont et al. 2004; Battaglia et al. 2006), but determine the age of stars with greater accuracy, revealing the detailed effects of different populations.”
Dark matter cores and cusps: the case of multiple stellar populations in dwarf spheroidals (2011, result): “This result has been revised and extended by a number of later investigations (e.g., Babusiaux et al. 2005; Battaglia et al. 2006, 2008a; Walker & Peñarrubia 2011).”
The Velocity Dispersion Profile of the Remote Dwarf Spheroidal Galaxy Leo I: A Tidal Hit and Run? (2007, background): “The fact that population and /or chemical gradients are commonly seen in other local dwarfs (Harbeck et al. 2001; Tolstoy et al. 2004; Battaglia et al. 2006) suggests that tidal stirring could be a common process.”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, methodology): “Evidence of stellar population segregation has been reported in Sculptor (Tolstoy et al. 2004), Fornax (Battaglia et al. 2006), and Sextans (Battaglia et al. 2011).”
A MegaCam Survey of Outer Halo Satellites. III. Photometric and Structural Parameters (2018, unknown): “◦2; Battaglia et al. 2006).”
The Cold Dark Matter Halos of Local Group Dwarf Spheroidals (2007, background): “The presence of well-defined and kinematicallydistinct populations of stars within some dSphs (Sculptor, Tolstoy et al. 2004; Fornax, Battaglia et al. 2006; Canis Venatici, Ibata et al. 2006), indeed, argues against tides as a major driver in the evolution of a dSph, since tidal stirring would tend…”
Gaia DR2 proper motions of dwarf galaxies within 420 kpc (2018, background): “Are the metallicity gradients observed for several of the Milky Way “classical” dwarf spheroidal galaxies (e.g. Tolstoy et al. 2004; Battaglia et al. 2006, 2011) an intrinsic property of these systems or could interactions with the Milky Way have had a role in setting their presence or erasing them…”
Axion dark matter, solitons and the cusp–core problem (2015, background): “They use the fact that some dSphs have been shown to have at least two stellar populations that are chemodynamically distinct (see e.g. Tolstoy et al. 2004; Battaglia et al. 2006, 2011).”
STELLAR VELOCITIES IN THE CARINA, FORNAX, SCULPTOR, AND SEXTANS dSph GALAXIES: DATA FROM THE MAGELLAN/MMFS SURVEY (2008, methodology): “…an extra dimension of information that can be used to study stellar metallicity distributions (e.g., Koch et al. 2006, 2007b) to identify correlations between kinematics and metallicity (Tolstoy et al. 2004; Battaglia et al. 2006), and to help clean samples of contaminating foreground stars.”
One Law to Rule Them All: The Radial Acceleration Relation of Galaxies (2016, background): “Some dSphs, however, show chemo-dynamically distinct stellar components (Tolstoy et al. 2004; Battaglia et al. 2006): one can distinguish between a metal-rich (MR) and a metal-poor (MP) component with the former more centrally concentrated and kinematically colder than the latter.”
Detailed abundances of a large sample of giant stars in M 54 and in the Sagittarius nucleus (2010, methodology): “For Sculptor and Fornax, we obtained the 1σ rms scatter from the FWHM of the histograms of metallicities presented by Tolstoy et al. (2004) and Battaglia et al. (2006), respectively.”
A METHOD FOR MEASURING (SLOPES OF) THE MASS PROFILES OF DWARF SPHEROIDAL GALAXIES (2011, background): “Fornax exhibits the same sort of bimodal horizontal branch morphology, but while Sculptor stopped forming stars as long as∼ 10 Gyr ago, Fornax has a young main sequence population with age of order∼ 100 Myr (Stetson et al. 1998; Battaglia et al. 2006).”
Velocity Dispersion Profiles of Seven Dwarf Spheroidal Galaxies (2007, background): “REFERENCES Armandroff, T. E., Olszewski, E. W., & Pryor, C. 1995, AJ, 110, 2131 Battaglia et al. 2006, A&A, 459, 423 Belokurov, V., , & et al. 2007, ApJ, 654, 897 Hargreaves, J. C., Gilmore, G., Irwin, M. J., & Carter, D. 1994, MNRAS, 269, 957 Ibata, R., Chapman, S., Irwin, M., Lewis, G., & Martin,…”
MULTI-ELEMENT ABUNDANCE MEASUREMENTS FROM MEDIUM-RESOLUTION SPECTRA. III. METALLICITY DISTRIBUTIONS OF MILKY WAY DWARF SATELLITE GALAXIES (2010, background): “Since then, the Dwarf Abundances and Radial Velocities Team (DART) have measured MDFs for Carina and Sextans in addition to Fornax and Sculptor (Tolstoy et al. 2004; Helmi et al. 2006; Battaglia et al. 2006, 2008b, 2010).”
Formation of isolated dwarf galaxies with feedback (2009, background): “Spectroscopic surveys of individual stars in several dwarf spheroidal galaxies of the Local Group (e.g. Battaglia et al. 2006) have revealed surprisingly complex star formation histories, sometimes over several Gyrs, and at least in one case in multiple bursts (Koch et al. 2006, 2008; Orban et al.…”
The Kinematic Status and Mass Content of the Sculptor Dwarf Spheroidal Galaxy (2008, methodology): “Furthermore, the combination of metallicity ([Fe/H]) and kinematic information have unveiled the presence of multiple stellar components in the Sculptor (Scl) and Fornax dSphs (Tolstoy et al. 2004, hereafter T04; Battaglia et al. 2006), where the metal rich (MR) stars have a more centrally concentra”
The Observed Properties of Dark Matter on Small Spatial Scales (2007, background): “…have been mapped to the (rather poorly defined concept of an) optical edge (Mateo 1997; Kleyna et al. 2002; Wilkinson et al. 2004, 2006;Muñoz et al. 2005; Sohn et al. 2007; Koch et al. 2007b; Battaglia et al. 2006; Walker et al. 2006)—see Figure 2 for a sample of profiles obtained by our group.”
THE UNIVERSAL STELLAR MASS–STELLAR METALLICITY RELATION FOR DWARF GALAXIES (2013, background): “For example, Fornax experienced multiple discrete episodes of star formation rather than one smoothly varying SFR (Buonanno et al. 1999; Saviane et al. 2000; Battaglia et al. 2006; Gullieuszik et al. 2007; Coleman & de Jong 2008).”
Analysis and calibration of CaII triplet spectroscopy of red giant branch stars from VLT/FLAMES observations (2007, methodology): “A similar study was made of a central field in Fornax (Letarte et al., in preparation, expected in 2008; Letarte 2007), for which 36 stars overlap our LR sample (Battaglia et al. 2006).”