Dark Matter annihilation energy output and its effects on the high-z IGM

We study the case of DM self annihilation, in order to assess its importance as an energy injection mechanism, to the IGM in general, and to the medium within particular DM haloes. We consider thermal relic WIMP particles with masses of 10GeV and 1TeV and we analyse in detail the clustering properties of DM in a $\Lambda$CDM cosmology, on all hierarchy levels, from haloes and their mass function, to subhaloes and the DM density profiles within them, considering adiabatic contraction by the presence of a SMBH. We then compute the corresponding energy output, concluding that DM annihilation does not constitute an important feedback mechanism. We also calculate the effects that DM annihilation has on the IGM temperature and ionization fraction, and we find that assuming maximal energy absorption, at z ~ 10, for the case of a 1TeV WIMP, the ionization fraction could be raised to $6 \times 10^{-4}$ and the temperature to 10K, and in the case of a 10GeV WIMP, the IGM temperature could be raised to 200K and the ionization fraction to $8 \times 10^{-3}$. We conclude that DM annihilations cannot be regarded as an alternative reionization scenario. Regarding the detectability of the WIMP through the modifications to the 21 cm differential brightness temperature signal ($\delta$Tb), we conclude that a thermal relic WIMP with mass of 1TeV is not likely to be detected from the global signal alone, except perhaps at the 1-3mK level in the frequency range 30MHz < $\nu$ < 35MHz corresponding to 40 < z < 46. However, a 10GeV mass WIMP may be detectable at the 1-3mK level in the frequency range 55MHz < $\nu$ < 119MHz corresponding to 11 < z < 25, and at the 1-10mK level in the frequency range 30MHz < $\nu$ < 40MHz corresponding to 35 < z < 46.Comment: 23 pages, 12 figures, accepted for publication in MNRA

Frequency domain analysis of the mean and osculating trajectories of LAGEOS-1

Several crucial developments in orbital mechanics are obtained through the method of averaging, which is equivalent to integrating only the dominant harmonics of the Fourier series of the dynamics. Frequency analysis of the trajectory expressed in orbital elements facilitates an in-depth understanding of Earth satellite dynamics, and facilitates the interpretation of numerical results from special perturbations within the theoretical framework of celestial mechanics. In this work, we examine recent Two-Line Element series for LAGEOS-1 in the frequency domain, highlighting the presence of short-periodic terms that are likely introduced in the generation of TLEs from observations. We also propose employing well-established methods from signal processing, such as spectrograms, to examine the evolution of dissipative systems such as satellites in LEO

Discovery of 6.035GHz Hydroxyl Maser Flares in IRAS18566+0408

We report the discovery of 6.035GHz hydroxyl (OH) maser flares toward the massive star forming region IRAS18566+0408 (G37.55+0.20), which is the only region known to show periodic formaldehyde (4.8 GHz H2CO) and methanol (6.7 GHz CH3OH) maser flares. The observations were conducted between October 2008 and January 2010 with the 305m Arecibo Telescope in Puerto Rico. We detected two flare events, one in March 2009, and one in September to November 2009. The OH maser flares are not simultaneous with the H2CO flares, but may be correlated with CH3OH flares from a component at corresponding velocities. A possible correlated variability of OH and CH3OH masers in IRAS18566+0408 is consistent with a common excitation mechanism (IR pumping) as predicted by theory.Comment: Accepted for publication in the Astrophysical Journa

High Resolution Observations of the Massive Protostar in IRAS18566+0408

We report 3 mm continuum, CH3CN(5-4) and 13CS(2-1) line observations with CARMA, in conjunction with 6 and 1.3 cm continuum VLA data, and 12 and 25 micron broadband data from the Subaru Telescope toward the massive proto-star IRAS18566+0408. The VLA data resolve the ionized jet into 4 components aligned in the E-W direction. Radio components A, C, and D have flat cm SEDs indicative of optically thin emission from ionized gas, and component B has a spectral index alpha = 1.0, and a decreasing size with frequency proportional to frequency to the -0.5 power. Emission from the CARMA 3 mm continuum, and from the 13CS(2-1), and CH3CN(5-4) spectral lines is compact (i.e. < 6700 AU), and peaks near the position of VLA cm source, component B. Analysis of these lines indicates hot, and dense molecular gas, typical for HMCs. Our Subaru telescope observations detect a single compact source, coincident with radio component B, demonstrating that most of the energy in IRAS18566+0408 originates from a region of size < 2400 AU. We also present UKIRT near-infrared archival data for IRAS18566+0408 which show extended K-band emission along the jet direction. We detect an E-W velocity shift of about 10 km/sec over the HMC in the CH3CN lines possibly tracing the interface of the ionized jet with the surrounding core gas. Our data demonstrate the presence of an ionized jet at the base of the molecular outflow, and support the hypothesis that massive protostars with O-type luminosity form with a mechanism similar to lower mass stars

Long-term Variability of H2_2CO Masers in Star-forming Regions

We present results of a multi-epoch monitoring program on variability of 6$\,$cm formaldehyde (H$_2$CO) masers in the massive star forming region NGC$\,$7538$\,$IRS$\,$1 from 2008 to 2015 conducted with the GBT, WSRT, and VLA. We found that the similar variability behaviors of the two formaldehyde maser velocity components in NGC$\,$7538$\,$IRS$\,$1 (which was pointed out by Araya and collaborators in 2007) have continued. The possibility that the variability is caused by changes in the maser amplification path in regions with similar morphology and kinematics is discussed. We also observed 12.2$\,$GHz methanol and 22.2$\,$GHz water masers toward NGC$\,$7538$\,$IRS$\,$1. The brightest maser components of CH$_3$OH and H$_2$O species show a decrease in flux density as a function of time. The brightest H$_2$CO maser component also shows a decrease in flux density and has a similar LSR velocity to the brightest H$_2$O and 12.2$\,$GHz CH$_3$OH masers. The line parameters of radio recombination lines and the 20.17 and 20.97$\,$GHz CH$_3$OH transitions in NGC$\,$7538$\,$IRS$\,$1 are also reported. In addition, we observed five other 6$\,$cm formaldehyde maser regions. We found no evidence of significant variability of the 6$\,$cm masers in these regions with respect to previous observations, the only possible exception being the maser in G29.96$-$0.02. All six sources were also observed in the H$_2^{13}$CO isotopologue transition of the 6$\,$cm H$_2$CO line; H$_2^{13}$CO absorption was detected in five of the sources. Estimated column density ratios [H$_2^{12}$CO]/[H$_2^{13}$CO] are reported.Comment: 29 pages, 9 figure

Hadamard matrices of orders 60 and 64 with automorphisms of orders 29 and 31

A classification of Hadamard matrices of order $2p+2$ with an automorphism of order $p$ is given for $p=29$ and $31$. The ternary self-dual codes spanned by the newly found Hadamard matrices of order $60$ with an automorphism of order $29$ are computed, as well as the binary doubly even self-dual codes of length $120$ with generator matrices defined by related Hadamard designs. Several new ternary near-extremal self-dual codes, as well as binary near-extremal doubly even self-dual codes with previously unknown weight enumerators are found.Comment: 21 page