10 research outputs found
ProtoEXIST: Advanced Prototype CZT Coded Aperture Telescopes for EXIST
{\it ProtoEXIST1} is a pathfinder for the {\it EXIST-HET}, a coded aperture
hard X-ray telescope with a 4.5 m CZT detector plane a 9070 degree
field of view to be flown as the primary instrument on the {\it EXIST} mission
and is intended to monitor the full sky every 3 h in an effort to locate GRBs
and other high energy transients. {\it ProtoEXIST1} consists of a 256 cm
tiled CZT detector plane containing 4096 pixels composed of an 88 array
of individual 1.95 cm 1.95 cm 0.5 cm CZT detector modules
each with a 8 8 pixilated anode configured as a coded aperture
telescope with a fully coded field of view employing
passive side shielding and an active CsI anti-coincidence rear shield, recently
completed its maiden flight out of Ft. Sumner, NM on the 9th of October 2009.
During the duration of its 6 hour flight on-board calibration of the detector
plane was carried out utilizing a single tagged 198.8 nCi Am-241 source along
with the simultaneous measurement of the background spectrum and an observation
of Cygnus X-1. Here we recount the events of the flight and report on the
detector performance in a near space environment. We also briefly discuss {\it
ProtoEXIST2}: the next stage of detector development which employs the {\it
NuSTAR} ASIC enabling finer (3232) anode pixilation. When completed
{\it ProtoEXIST2} will consist of a 256 cm tiled array and be flown
simultaneously with the ProtoEXIST1 telescope
Galaxy formation with Wave/Fuzzy Dark Matter: The core-halo structure
Dark matter-dominated cores have long been claimed for the well-studied local
group dwarf galaxies. More recently, extended stellar halos have been uncovered
around several of these dwarfs through deeper imaging and spectroscopy. Such
core-halo structures are not a feature of conventional cold dark matter (CDM),
based on collisionless particles where smooth, scale-free profiles are
predicted. In contrast, smooth and prominent dark matter cores are predicted
for Warm and Fuzzy/Wave Dark Matter (WDM/DM) respectively. The question
arises to what extent the visible stellar profiles should reflect this dark
matter core structure. Here we compare cosmological hydrodynamical simulations
of CDM, WDM DM, aiming to predict the stellar profiles for these
three DM scenarios. We show that cores surrounded by extended halos are
distinguishable for WDM and DM, with the most prominent cores in the case
of DM, where the stellar density is enhanced in the core due to the
presence of the relatively dense soliton. Our analysis demonstrates that such
behavior does not appear in CDM, implying that the small-scale cut-off in the
power spectrum present for WDM and DM provides a core-halo transition.
Consequently, we estimate the mass of the DM particle at this core-halo
transition point. Furthermore, we observe the anticipated asymmetry for
DM due to the soliton's random walk, a distinctive characteristic not
found in the symmetric distributions of stars in Warm and CDM models.Comment: 17 pages and 15 figure
Galaxy formation with Wave/Fuzzy Dark Matter: The core-halo structure
International audienceDark matter-dominated cores have long been claimed for the well-studied local group dwarf galaxies. More recently, extended stellar halos have been uncovered around several of these dwarfs through deeper imaging and spectroscopy. Such core-halo structures are not a feature of conventional cold dark matter (CDM), based on collisionless particles where smooth, scale-free profiles are predicted. In contrast, smooth and prominent dark matter cores are predicted for Warm and Fuzzy/Wave Dark Matter (WDM/DM) respectively. The question arises to what extent the visible stellar profiles should reflect this dark matter core structure. Here we compare cosmological hydrodynamical simulations of CDM, WDM DM, aiming to predict the stellar profiles for these three DM scenarios. We show that cores surrounded by extended halos are distinguishable for WDM and DM, with the most prominent cores in the case of DM, where the stellar density is enhanced in the core due to the presence of the relatively dense soliton. Our analysis demonstrates that such behavior does not appear in CDM, implying that the small-scale cut-off in the power spectrum present for WDM and DM provides a core-halo transition. Consequently, we estimate the mass of the DM particle at this core-halo transition point. Furthermore, we observe the anticipated asymmetry for DM due to the soliton's random walk, a distinctive characteristic not found in the symmetric distributions of stars in Warm and CDM models
Galaxy formation with Wave/Fuzzy Dark Matter: The core-halo structure
International audienceDark matter-dominated cores have long been claimed for the well-studied local group dwarf galaxies. More recently, extended stellar halos have been uncovered around several of these dwarfs through deeper imaging and spectroscopy. Such core-halo structures are not a feature of conventional cold dark matter (CDM), based on collisionless particles where smooth, scale-free profiles are predicted. In contrast, smooth and prominent dark matter cores are predicted for Warm and Fuzzy/Wave Dark Matter (WDM/DM) respectively. The question arises to what extent the visible stellar profiles should reflect this dark matter core structure. Here we compare cosmological hydrodynamical simulations of CDM, WDM DM, aiming to predict the stellar profiles for these three DM scenarios. We show that cores surrounded by extended halos are distinguishable for WDM and DM, with the most prominent cores in the case of DM, where the stellar density is enhanced in the core due to the presence of the relatively dense soliton. Our analysis demonstrates that such behavior does not appear in CDM, implying that the small-scale cut-off in the power spectrum present for WDM and DM provides a core-halo transition. Consequently, we estimate the mass of the DM particle at this core-halo transition point. Furthermore, we observe the anticipated asymmetry for DM due to the soliton's random walk, a distinctive characteristic not found in the symmetric distributions of stars in Warm and CDM models
Galaxy formation with Wave/Fuzzy Dark Matter: The core-halo structure
International audienceDark matter-dominated cores have long been claimed for the well-studied local group dwarf galaxies. More recently, extended stellar halos have been uncovered around several of these dwarfs through deeper imaging and spectroscopy. Such core-halo structures are not a feature of conventional cold dark matter (CDM), based on collisionless particles where smooth, scale-free profiles are predicted. In contrast, smooth and prominent dark matter cores are predicted for Warm and Fuzzy/Wave Dark Matter (WDM/DM) respectively. The question arises to what extent the visible stellar profiles should reflect this dark matter core structure. Here we compare cosmological hydrodynamical simulations of CDM, WDM DM, aiming to predict the stellar profiles for these three DM scenarios. We show that cores surrounded by extended halos are distinguishable for WDM and DM, with the most prominent cores in the case of DM, where the stellar density is enhanced in the core due to the presence of the relatively dense soliton. Our analysis demonstrates that such behavior does not appear in CDM, implying that the small-scale cut-off in the power spectrum present for WDM and DM provides a core-halo transition. Consequently, we estimate the mass of the DM particle at this core-halo transition point. Furthermore, we observe the anticipated asymmetry for DM due to the soliton's random walk, a distinctive characteristic not found in the symmetric distributions of stars in Warm and CDM models