Extended Hot Halos Around Isolated Galaxies Observed in the ROSAT All-Sky Survey

We place general constraints on the luminosity and mass of hot X-ray emitting gas residing in extended "hot halos" around nearby massive galaxies. We examine stacked images of 2165 galaxies from the 2MASS Very Isolated Galaxy Catalog (2MVIG), as well as subsets of this sample based on galaxy morphology and K-band luminosity. We detect X-ray emission at high confidence (ranging up to nearly 10\sigma) for each subsample of galaxies. The average L_X within 50 kpc is 1.0\pm0.1 (statistical) \pm0.2 (systematic) x10^40 erg/s, although the early-type galaxies are more than twice as luminous as the late-type galaxies. Using a spatial analysis, we also find evidence for extended emission around five out of seven subsamples (the full sample, the luminous galaxies, early-type galaxies, luminous late-type galaxies, and luminous early-type galaxies) at 92.7%, 99.3%, 89.3%, 98.7%, and 92.1% confidence, respectively. Several additional lines of evidence also support this conclusion and suggest that about 1/2 of the total emission is extended, and about 1/3 of the extended emission comes from hot gas. For the sample of luminous galaxies, which has the strongest evidence for extended emission, the average hot gas mass is 4x10^9 Msun within 50 kpc and the implied accretion rate is 0.4 Msun/yr.Comment: 23 pages, 21 figures, 4 tables. Accepted for publication in ApJ (v2 revised to reflect minor changes made in proofs

Polarization amplitudes in τ−→ντVP\tau^- \to \nu_{\tau} V P decay beyond the standard model

We use a recent formalism of the weak hadronic reactions $\tau^- \to \nu_{\tau} M_1 M_2$ to study the helicity amplitudes in $\tau^- \to \nu_{\tau} V P$ decay. This recent formalism maps the transition matrix elements at the quark level into hadronic matrix elements, and finally writes the weak matrix elements in terms of easy analytical formulas evaluated by means of an elaborate angular momentum algebra. The formalism provides directly the amplitudes for the different spin third components of the vector mesons involved. We extend the formalism to a general case, with the operator $\gamma^\mu -\alpha\gamma^\mu \gamma_5$, that can account for different models beyond the standard model and study in detail the $\tau^- \to \nu_{\tau} K^{*0} K^{-}$ reaction for the different helicities of the $K^{*0}$. The results are shown in terms of the $\alpha$ parameter that differs for each model. We find that $\frac{d \Gamma}{d M_{\rm inv}^{(K^{*0} K^{-} )}}$ is very different for the different components $M=\pm 1, 0$ and in particular the magnitude $\frac{d \Gamma}{d M_{\rm inv}^{(K^{*0} K^{-} )}}|_{M=+1} -\frac{d \Gamma}{d M_{\rm inv}^{(K^{*0} K^{-} )}}|_{M=-1}$ is very sensitive to the $\alpha$ parameter, which makes the investigation of this magnitude a most welcome initiative to test different models beyond the standard model.Comment: 20 pages, 6 figures, add some discussion

B0→D0Dˉ0K0B^0 \to D^0 \bar D^0 K^0, B+→D0Dˉ0K+B^+ \to D^0 \bar D^0 K^+ and the scalar DDˉD \bar D bound state

We study the $B^0$ decay to $D^0 \bar D^0 K^0$ based on the chiral unitary model that generates the X(3720) resonance, and make predictions for the $D^0 \bar D^0$ invariant mass distribution. From the shape of the distribution, the existence of the resonance below threshold could be induced. We also predict the rate of production of the X(3720) resonance to the $D^0 \bar D^0$ mass distribution with no free parameters.Comment: 9 pages, 17 figure

Impacts of land use, restoration, and climate change on tropical peat carbon stocks in the 21st century: Implications for climate mitigation

The climate mitigation potential of tropical peatlands has gained increased attention as Southeast Asian peatlands are being deforested, drained and burned at very high rates, causing globally significant carbon dioxide (CO2) emissions to the atmosphere. We used a process-based dynamic tropical peatland model to explore peat carbon (C) dynamics of several management scenarios within the context of simulated twenty-first century climate change. Simulations of all scenarios with land use, including restoration, indicated net C losses over the twenty-first century ranging from 10 to 100 % of pre-disturbance values. Fire can be the dominant C-loss pathway, particularly in the drier climate scenario we tested. Simulated 100 years of oil palm (Elaeis guineensis) cultivation with an initial prescribed burn resulted in 2400–3000 Mg CO2 ha−1 total emissions. Simulated restoration following one 25-year oil palm rotation reduced total emissions to 440–1200 Mg CO2 ha−1, depending on climate. These results suggest that even under a very optimistic scenario of hydrological and forest restoration and the wettest climate regime, only about one third of the peat C lost to the atmosphere from 25 years of oil palm cultivation can be recovered in the following 75 years if the site is restored. Emissions from a simulated land degradation scenario were most sensitive to climate, with total emissions ranging from 230 to 10,600 Mg CO2 ha−1 over 100 years for the wettest and driest dry season scenarios, respectively. The large difference was driven by increased fire probability. Therefore, peat fire suppression is an effective management tool to maintain tropical peatland C stocks in the near term and should be a high priority for climate mitigation efforts. In total, we estimate emissions from current cleared peatlands and peatlands converted to oil palm in Southeast Asia to be 8.7 Gt CO2 over 100 years with a moderate twenty-first century climate. These emissions could be minimized by effective fire suppression and hydrological restoration

High energy neutrinos from magnetars

Magnetars can accelerate cosmic rays to high energies through the unipolar effect, and are also copious soft photon emitters. We show that young, fast-rotating magnetars whose spin and magnetic moment point in opposite directions emit high energy neutrinos from their polar caps through photomeson interactions. We identify a neutrino cut-off band in the magnetar period-magnetic field strength phase diagram, corresponding to the photomeson interaction threshold. Within uncertainties, we point out four possible neutrino emission candidates among the currently known magnetars, the brightest of which may be detectable for a chance on-beam alignment. Young magnetars in the universe would also contribute to a weak diffuse neutrino background, whose detectability is marginal, depending on the typical neutrino energy.Comment: emulateapj style, 6 pages, 1 figure, ApJ, v595, in press. Important contributions from Dr. Harding added. Major revisions made. More conservative and realistic estimates about the neutrino threshold condition and emission efficiency performed. More realistic typical beaming angle and magnetar birth rate adopte

Helicity amplitudes in B→D∗νˉlB \to D^{*} \bar{\nu} l decay

We use a recent formalism of the weak hadronic reactions that maps the transition matrix elements at the quark level into hadronic matrix elements, evaluated with an elaborate angular momentum algebra that allows finally to write the weak matrix elements in terms of easy analytical formulas. In particular they appear explicitly for the different spin third components of the vector mesons involved. We extend the formalism to a general case, with the operator $\gamma^\mu -\alpha\gamma^\mu \gamma_5$, that can accommodate different models beyond the standard model and study in detail the $B \to D^{*} \bar{\nu} l$ reaction for the different helicities of the $D^*$. The results are shown for each amplitude in terms of the $\alpha$ parameter that is different for each model. We show that $\frac{d \Gamma}{d M_{\rm inv}^{(\nu l)}}$ is very different for the different components $M=\pm 1, 0$ and in particular the magnitude $\frac{d \Gamma}{d M_{\rm inv}^{(\nu l)}}|_{M=-1} -\frac{d \Gamma}{d M_{\rm inv}^{(\nu l)}}|_{M=+1}$ is very sensitive to the $\alpha$ parameter, which suggest to use this magnitude to test different models beyond the standard model. We also compare our results with the standard model and find very similar results, and practically identical at the end point of $M_{\rm inv}^{(\nu l)}= m_B- m_{D^*}$.Comment: 25 pages, 10 figure

Radiative decay of the dynamically generated open and hidden charm scalar meson resonances D_{s0}^*(2317) and X(3700)

We present the formalism for the decay of dynamically generated scalar mesons with open- or hidden-charm and give results for the decay of D^*_{s0} (2317) to \gamma D_s^* plus that of a hidden charm scalar meson state predicted by the theory around 3700 MeV decaying into \gamma J/\psi.Comment: Appendix adde