Core-Cusp revisited and Dark Matter Phase Transition Constrained at O(0.1) eV with LSB Rotation Curve

Recently a new particle physics model called Bound Dark Matter (BDM) has been proposed in which dark matter (DM) particles are massless above a threshold energy (Ec) and acquire mass below it due to nonperturbative methods. Therefore, the BDM model describes DM particles which are relativistic, hot dark matter, in the inner regions of galaxies and describes nonrelativistic, cold dark matter, where halo density is below rho_c = Ec^4. To realize this idea in galaxies we use a particular DM cored profile that contains three parameters: a scale length (rs) and density (rho_0) of the halo, and a core radius (rc) stemming from the relativistic nature of the BDM model. We test this model by fitting rotation curves of seventeen Low Surface Brightness galaxies from The HI Nearby Galaxy Survey (THINGS). Since the energy Ec parameterizes the phase transition due to the underlying particle physics model, it is independent on the details of galaxy or structure formation and therefore the DM profile parameters rs, rc, Ec are constrained, leaving only two free parameters. The high spatial and velocity resolution of this sample allows to derive the model parameters through the numerical implementation of the chi^2-goodness-of-fit test to the mass models. We compare the fittings with those of Navarro-Frenk-White (NFW), Burkert, and Pseudo-Isothermal (ISO) profiles. Through the results we conclude that the BDM profile fits better, or equally well, than NFW, Burkert, and ISO profiles and agree with previous results implying that cored profiles are preferred over the N-body motivated cuspy profile. We also compute 2D likelihoods of the BDM parameters rc and Ec for the different galaxies and matter contents, and find an average galaxy core radius rc=300 pc and a transition energy Ec = 0.11 eV when the DM halo is the only component. In Kroupa mass model, we obtain a core rc=1.48 kpc, and energy Ec=0.06 eV.Comment: 54 pages, 26 Figures. Submitted to Phys. Rev. D. Refer also to Phys.Rev.D84:121301,201

Galactic phase transition at Ec=0.11 eV from rotation curves of cored LSB galaxies and nonperturbative dark matter mass

We analyze the a set of seventeen rotation curves of Low Surface Brightness (LSB) galaxies from the The HI Nearby Galaxy Survey (THINGS) with different mass models to study the core structure and to determine a phase transition energy scale (E_c) between hot and cold dark matter, due to nonperturbative effects in the Bound Dark Matter (BDM) model. Our results agree with previous ones implying the cored profiles are preferred over the N-body motivated cuspy NFW profile. We find an average galactic core radius of r_c = 260 \times 10^{+/- 1.3} pc and a phase transition energy E_c = 0.11\times 10^{+/- 0.46} eV, that is of the same order of magnitude as the sum of the neutrino masses.Comment: 5 pages, 1 figure

The impact of human expert visual inspection on the discovery of strong gravitational lenses

We investigate the ability of human ’expert’ classifiers to identify strong gravitational lens candidates in Dark Energy Survey like imaging. We recruited a total of 55 people that completed more than 25% of the project. During the classification task, we present to the participants 1489 images. The sample contains a variety of data including lens simulations, real lenses, non-lens examples, and unlabeled data. We find that experts are extremely good at finding bright, well-resolved Einstein rings, whilst arcs with g-band signal-to-noise less than ∼25 or Einstein radii less than ∼1.2 times the seeing are rarely recovered. Very few non-lenses are scored highly. There is substantial variation in the performance of individual classifiers, but they do not appear to depend on the classifier’s experience, confidence or academic position. These variations can be mitigated with a team of 6 or more independent classifiers. Our results give confidence that humans are a reliable pruning step for lens candidates, providing pure and quantifiably complete samples for follow-up studies