The Dwarf Galaxy DDO 47 as a Dark Matter Laboratory: Testing Cusps Hiding in Triaxial Halos

By G. Gentile, Andreas Burkert, P. Salucci, Uli Klein, F. Walter. 2005

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We present an analysis of high-resolution H I data of the dwarf galaxy DDO 47, aimed at testing the hypothesis that dark halo triaxiality might induce noncircular motions resulting in rotation curves best fitted by cored halos, even if the dark matter halo is intrinsically cuspy. This hypothesis could be invoked in order to reconcile the predictions of the standard ΛCDM theory with the rotation curves of disk galaxies. DDO 47 is an ideal case to test this hypothesis because it has a very regular velocity field, its rotation curve is best fitted by a cored halo, and an NFW halo is inconsistent with the data. We analyze the velocity field through the higher order harmonic terms in order to search for kinematical signatures of alleged noncircular motions needed to "hide" a cusp: the result is that globally noncircular motions are at a level of 2-3 km s-1, and they are more likely to be associated with the presence of some spiral structure than with a global elongated potential (e.g., a triaxial halo). These noncircular motions are far from being sufficient to account for the discrepancy with the ΛCDM predictions. We therefore conclude that the dark matter halo around the dwarf galaxy DDO 47 is truly cored and that a cusp cannot be hidden by noncircular motions.

Subfields: Astronomy and Astrophysics, Instrumentation, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/302cb4e60cc2a63850e5caa655ee192531abea90

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Citations in the corpus

NGC 3741: the dark halo profile from the most extended rotation curve (2006, background): “Gentile et al. (2005) analysed the velocity field of DDO 47 (of which the rotation curve is best fitted by a cored halo) through its harmonic decomposition and found non-circular motions of the order of only 2–3 km s−1, an order of magnitude smaller than the discrepancy between the observations and…”
THE CENTRAL SLOPE OF DARK MATTER CORES IN DWARF GALAXIES: SIMULATIONS VERSUS THINGS (2010, background): “…as beam smearing, center offset and non-circular motions, which may play a role in hiding central cusps (Blais-Ouellette et al. 1999; van den Bosch et al. 2000; Bolatto et al. 2002; Swaters et al. 2003; Simon et al. 2003; Rhee et al. 2004; Gentile et al. 2005; Spekkens et al. 2005; Oh et al. 2008).”
The dark matter density at the Sun’s location (2010, background): “The accuracy of the “measurements” is excellent and the results are at the core of the present debates on Galaxy formation (e.g. Gentile et al. 2004, 2005; DeBlok 2010).”
Analysis of rotation curves in the framework of Rn gravity (2007, background): “This sample includes nearby galaxies of different surface brightnesses: DDO 47 (Gentile et al. 2005); ESO 116-G12, ESO 287-G13, NGC 7339 and 1090 (Gentile et al. 2004); UGC 8017, UGC 10981, UGC 11455 (Vogt et al. 2004); M31, M33 (Corbelli & Salucci 2007); IC 2574 (Martimbeau, Carignan & Roy 1994),…”
HIGH-RESOLUTION ROTATION CURVES AND GALAXY MASS MODELS FROM THINGS (2008, background): “This core has a typical size of order a kpc (e.g., Moore 1994; de Blok et al. 1996; de Blok & McGaugh 1997; de Blok et al. 2001; de Blok & Bosma 2002; Marchesini et al. 2002; Weldrake et al. 2003; Gentile et al. 2005; Kuzio de Naray et al. 2006; Gentile et al. 2007).”
On the frequency, intensity, and duration of starburst episodes triggered by galaxy interactions and mergers (2008, background): “This has been shown to be valid either for dwarf galaxies (Flores & Primack 1994; Marchesini et al. 2002; Gentile et al. 2005), or for Low Surface Brightness (LSB) galaxies (de Blok et al. 2001; McGaugh et al. 2001; Marchesini et al. 2002; Kuzio de Naray et al. 2006, 2008).”
A constant dark matter halo surface density in galaxies (2009, methodology): “…Rotation Curve (URC, PSS); (b) NGC3741, the most dark matter dominated Spiral in the local Universe and DDO 47, a very well studied dwarf spiral (Gentile et al. 2005) by χ2 modelling their kinematics; (c) the THINGS sample (Walter et al. 2008): disk galaxies with high quality RCs that have…”
Concentration, spin and shape of dark matter haloes as a function of the cosmological model: WMAP1, WMAP3 and WMAP5 results (2008, background): “…between the inner density slopes of dwarf and LSB galaxies and those predicted by CDM (e.g., Moore 1994; Flores & Primack 1994; van den Bosch & Swaters 2001; de Blok et al. 2001, 2002; Swaters et al. 2003, Dutton et al. 2005; Gentile et al. 2005; Simon et al. 2005; Kuzio de Naray et al. 2008).”
The Dynamical and Chemical Evolution of Dwarf Spheroidal Galaxies with GEAR (2009, background): “…is supported by observations of normal low brightness and dwarf galaxies (Blais-Ouellette et al. 2001; de Blok & Bosma 2002; Swaters et al. 2003; Gentile et al. 2004, 2005; Spekkens et al. 2005; de Blok 2005; de Blok et al. 2008; Spano et al. 2008; Walker & Peñarrubia 2011), including the…”
The Core-Cusp Problem (2009, background): “As described earlier, work on high-resolution velocity fields by Gentile et al. (2005), Trachternach et al. (2008) and Kuzio de Naray et al. (2009) has put significant observational constraints on the strength of non-circular motions and theellipticity of the (equatorial) potential.”
HIGH-RESOLUTION DARK MATTER DENSITY PROFILES OF THINGS DWARF GALAXIES: CORRECTING FOR NONCIRCULAR MOTIONS (2008, unknown): “For one dwarf LSB galaxy (DDO 47), Gentile et al. (2005) have quantified the noncircular motions and found them to be ∼2 km s−1, i.e., to small by about an order of magnitude to explain the ΛCDM discrepancy.”