TY  - JOUR
A1  - Abeysekara, A. U.
A1  - Archer, A.
A1  - Benbow, Wystan
A1  - Bird, Ralph
A1  - Brill, A.
A1  - Brose, Robert
A1  - Buchovecky, M.
A1  - Calderon-Madera, D.
A1  - Christiansen, J. L.
A1  - Cui, W.
A1  - Daniel, M. K.
A1  - Falcone, A.
A1  - Feng, Q.
A1  - Fernandez-Alonso, M.
A1  - Finley, J. P.
A1  - Fortson, Lucy
A1  - Furniss, Amy
A1  - Gent, A.
A1  - Giuri, C.
A1  - Gueta, O.
A1  - Hanna, David
A1  - Hassan, T.
A1  - Hervet, Oliver
A1  - Holder, J.
A1  - Hughes, G.
A1  - Humensky, T. B.
A1  - Johnson, Caitlin A.
A1  - Kaaret, P.
A1  - Kertzman, M.
A1  - Kieda, David
A1  - Krause, Maria
A1  - Krennrich, F.
A1  - Kumar, S.
A1  - Lang, M. J.
A1  - Maier, Gernot
A1  - Moriarty, P.
A1  - Mukherjee, Reshmi
A1  - Nievas-Rosillo, M.
A1  - Ong, R. A.
A1  - Pfrang, Konstantin Johannes
A1  - Pohl, Martin
A1  - Prado, R. R.
A1  - Pueschel, Elisa
A1  - Quinn, J.
A1  - Ragan, K.
A1  - Reynolds, P. T.
A1  - Ribeiro, D.
A1  - Richards, G. T.
A1  - Roache, E.
A1  - Rovero, A. C.
A1  - Sadeh, Iftach
A1  - Santander, M.
A1  - Sembroski, G. H.
A1  - Shahinyan, Karlen
A1  - Sushch, Iurii
A1  - Svraka, T.
A1  - Weinstein, A.
A1  - Wells, R. M.
A1  - Wilcox, Patrick
A1  - Wilhelm, Alina
A1  - Williams, David Arnold
A1  - Williamson, T. J.
A1  - Zitzer, B.
T1  - Measurement of the Extragalactic Background Light Spectral Energy Distribution with VERITAS
JF  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - The extragalactic background light (EBL), a diffuse photon field in the optical and infrared range, is a record of radiative processes over the universe?s history. Spectral measurements of blazars at very high energies (>100 GeV) enable the reconstruction of the spectral energy distribution (SED) of the EBL, as the blazar spectra are modified by redshift- and energy-dependent interactions of the gamma-ray photons with the EBL. The spectra of 14 VERITAS-detected blazars are included in a new measurement of the EBL SED that is independent of EBL SED models. The resulting SED covers an EBL wavelength range of 0.56?56 ?m, and is in good agreement with lower limits obtained by assuming that the EBL is entirely due to radiation from cataloged galaxies.
KW  - Extragalactic astronomy
KW  - Active galactic nuclei
KW  - Diffuse radiation
KW  - Cosmology
Y1  - 2019
U6  - https://doi.org/10.3847/1538-4357/ab4817
SN  - 0004-637X
SN  - 1538-4357
VL  - 885
IS  - 2
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Baushev, Anton N.
T1  - The real and apparent convergence of N-body simulations of the dark matter structures: Is the Navarro-Frenk-White profile real?
JF  - Astroparticle physics
N2  - While N-body simulations suggest a cuspy profile in the centra of the dark matter halos of galaxies, the majority of astronomical observations favor a relatively soft cored density distribution of these regions. The routine method of testing the convergence of N-body simulations (in particular, the negligibility of two-body scattering effect) is to find the conditions under which formed structures is insensitive to numerical parameters. The results obtained with this approach suggest a surprisingly minor role of the particle collisions: the central density profile remains untouched and close to the Navarro-Frenk-White shape, even if the simulation time significantly exceeds the collisional relaxation time tau(r). In order to check the influence of the unphysical test body collisions we use the Fokker-Planck equation. It turns out that a profile rho proportional to r(-beta) where beta similar or equal to 1 is an attractor: the Fokker-Planck diffusion transforms any reasonable initial distribution into it in a time shorter than tau(r), and then the cuspy profile should survive much longer than tau(r), since the Fokker-Planck diffusion is self-compensated if beta similar or equal to 1. Thus the purely numerical effect of test body scattering may create a stable NFW-like pseudosolution. Moreover, its stability may be mistaken for the simulation convergence. We present analytical estimations for this potential bias effect and call for numerical tests. For that purpose, we suggest a simple test that can be performed as the simulation progresses and would indicate the magnitude of the collisional influence and the veracity of the simulation results. (C) 2014 Elsevier B.V. All rights reserved.
KW  - Dark matter
KW  - Singularities
KW  - Cosmology
KW  - Dwarf galaxies
Y1  - 2015
U6  - https://doi.org/10.1016/j.astropartphys.2014.07.012
SN  - 0927-6505
SN  - 1873-2852
VL  - 62
SP  - 47
EP  - 53
PB  - Elsevier
CY  - Amsterdam
ER  -