2,521 research outputs found
Electromagnetic counterparts of high-frequency gravitational waves having additional polarization states: distinguishing and probing tensor-mode, vector-mode and scalar-mode gravitons
GWs from extra dimensions, very early universe, and some high-energy
astrophysical process, might have at most six polarizations: plus- and
cross-type (tensor-mode gravitons), x-, y-type (vector-mode), and b-, l-type
(scalar-mode). Peak or partial peak regions of some of such GWs are just
distributed in GHz or higher frequency band, which would be optimal band for
electromagnetic(EM) response. In this paper we investigate EM response to such
high-frequency GWs(HFGWs) having additional polarizations. For the first time
we address:(1)concrete forms of analytic solutions for perturbed EM fields
caused by HFGWs having all six possible polarizations in background stable EM
fields; (2)perturbed EM signals of HFGWs with additional polarizations in
three-dimensional-synchro-resonance-system(3DSR system) and in
galactic-extragalactic background EM fields. These perturbative EM fields are
actually EM counterparts of HFGWs, and such results provide a novel way to
simultaneously distinguish and display all possible six polarizations. It is
also shown: (i)In EM response, pure cross-, x-type and pure y-type
polarizations can independently generate perturbative photon fluxes(PPFs,
signals), while plus-, b- and l-type polarizations produce PPFs in different
combination states. (ii) All such six polarizations have separability and
detectability. (iii)In EM response to HFGWs from extra-dimensions,
distinguishing and displaying different polarizations would be quite possible
due to their very high frequencies, large energy densities and special
properties of spectrum. (iv)Detection band(10^8 to 10^12 Hz or higher) of PPFs
by 3DSR and observation range(7*10^7 to 3*10^9 Hz) of PPFs by FAST
(Five-hundred-meter-Aperture-Spherical Telescope, China), have a certain
overlapping property, so their coincidence experiments will have high
complementarity.Comment: 27 pages, 16 figure
Distinguishing thermal histories of dark matter from structure formation
It is important to understand the implications of current observational
constraints and potential signatures on the thermal history of dark matter. In
this paper, we build the connection between the present-day velocities and the
production mechanism of dark matter and find that the current observation on
structure formation can be imposed to constrain the decoupling temperatures and
the phase-space distribution of dark matter. We further explore the potential
of distinguishing different possible thermal histories of dark matter with
hypothetical future observational data. Using the freeze-in/-out scenarios as
templates, we find that future precision data may uniquely identify the allowed
parameter spaces for freeze-in and freeze-out, or even completely rule out one
of the scenarios. This method can be more generally applied to other scenarios.Comment: 49 pages, 13 figures, 1 tabl
4-(4-Nitrobenzenesulfonamido)pyridinium chloride
In the title compound, C11H10N3O4S+·Cl−, the benzene ring makes an angle of 89.2 (1)° with the pyridinium ring. The dihedral angle between the nitro group and the benzene ring is 15.7 (1)°. The crystal structure is stabilized by N—H⋯Cl hydrogen bonds
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