Discovery of water vapor megamaser emission from Mrk1419 (NGC 2690): An analogue of NGC 4258?

Water vapor emission at 22 GHz is reported from the nucleus of the LINER galaxy Mrk 1419 (NGC 2960). Single-dish spectra of the maser source show properties that are similar to those seen in NGC 4258, namely (1) a cluster of systemic H2O features, (2) two additional H2O clusters, one red- and one blue-shifted by about 475 km/s, (3) a likely acceleration of the systemic features, and (4) no detectable velocity drifts in the red- and blue-shifted features. Interpreting the data in terms of the paradigm established for NGC 4258, i.e. assuming the presence of an edge-on Keplerian circumnuclear annulus with the systemic emission arising from the near side of its inner edge, the following parameters are derived: Rotational velocity: 330-600 km/s; radius: 0.13-0.43 pc; binding mass: about 10 million solar masses. With the galaxy being approximately ten times farther away than NGC 4258, a comparison of linear and angular scales (the latter via Very Long Baseline Interferometry) may provide an accurate geometric distance to Mrk 1419 that could be used to calibrate the cosmic distance scale.Comment: 4 pages, 5 Postscript figures, A&A Letter

Elements for the Expected Mechanisms on Reduced Emissions from Deforestation and Degradation, REDD under UNFCCC

Carbon emissions from deforestation and degradation account for 20% of the global anthropogenic emissions (IPCC WG I, 2007). Since the eleventh session of the Conference of the Parties to the United Nations Convention on Climate Change (UNFCCC) in December 2005, strategies and incentives for Reduced Emissions from Deforestation and Degradation (REDD) have emerged as one of the most attended negotiation items. It is not easy to build an international agreement on the role of REDD in a future climate change regime, but now we are close to an achievable historical decision on the future of forests: the Bali mandate on REDD. In this paper we suggest some elements for an effective long-term implementation of a REDD mechanism under the UNFCCC and for closing gaps in the forestry accounting system. These elements are related both to ecological and political processes, reflecting some of the most critical and debated negotiation points. The proposed elements are: a) carbon (C) losses from forests; b) incentives for all stages of reducing emissions, stabilizing and maintaining forest C stocks; c) national approach; d) data availability at national scale; e) conservativeness approach for carbon accounting.JRC.H.2-Climate chang

On the nuclear obscuration of H2O maser galaxies

To shed light onto the circumnuclear environment of 22 GHz H2O maser galaxies, we have analyzed some of their multi-wavelength properties, including the far infrared luminosity (FIR), the luminosity of the [O III]\lambda5007 emission line, the nuclear X-ray luminosity, and the equivalent width of the neutral iron Ka emission line (EW (Ka)). Our statistical analysis includes a total of 85 sources, most of them harboring an active galactic nucleus (AGN). There are strong anti-correlations between EW (Ka) and two "optical thickness parameters", i.e. the ratios of the X-ray luminosity versus the presumably more isotropically radiated [O III] and far infrared (FIR) luminosities. Based on these anti-correlations, a set of quantitative criteria, EW (Ka) > 300eV, L_{2-10keV} 600L_{2-10keV} can be established for Compton-thick nuclear regions. 18 H2O maser galaxies belong to this category. There are no obvious correlations between the EW (Ka), the [O III] luminosity and the isotropic H2O maser luminosity. When comparing samples of Seyfert 2s with and without detected H2O maser lines, there seem to exist differences in EW (Ka) and the fraction of Compton-thick nuclei. This should be studied further. For AGN masers alone, there is no obvious correlation between FIR and H2O maser luminosities. However, including masers associated with star forming regions, a linear correlation is revealed. Overall, the extragalactic FIR-H2O data agree with the corresponding relation for Galactic maser sources, extrapolated by several orders of magnitude to higher luminosities.Comment: 32 pages with 5 figures and 2 tables, accepted for publication in Ap

The density, the cosmic microwave background and the proton-to-electron mass ratio in a cloud at redshift 0.9

Based on measurements with the Effelsberg 100-m telescope, a multi-line study of molecular species is presented toward the gravitational lens system PKS 1830–211, which is by far the best known target to study dense cool gas in absorption at intermediate redshift. Determining average radial velocities and performing Large Velocity Gradient radiative transfer calculations, the aims of this study are (1) to determine the density of the gas, (2) to constrain the temperature of the cosmic microwave background (CMB), and (3) to evaluate the proton-to-electron mass ratio at redshift z ∼ 0.89. Analyzing data from six rotational HC_3N transitions (this includes the J = 7 ← 6 line, which is likely detected for the first time in the interstellar medium) we obtain n(H_2) ∼ 2600 cm^(−3) for the gas density of the south-western absorption component, assuming a background source covering factor, which is independent of frequency. With a possibly more realistic frequency dependence proportional to ν^(0.5) (the maximal exponent permitted by observational boundary conditions), n(H2) ∼ 1700 cm^(−3). Again toward the south-western source, excitation temperatures of molecular species with optically thin lines and higher rotational constants are, on average, consistent with the expected temperature of the cosmic microwave background, T^(CMB) = 5.14 K. However, individually, there is a surprisingly large scatter which far surpasses expected uncertainties. A comparison of CS J = 1 ← 0 and 4 ← 3 optical depths toward the weaker north-western absorption component results in T_(ex) = 11 K and a 1-σ error of 3 K. For the main component, a comparison of velocities determined from ten optically thin NH_3 inversion lines with those from five optically thin rotational transitions of HC_3N, observed at similar frequencies, constrains potential variations of the proton-to-electron mass ratio μ to Δμ/μ < 1.4 × 10^(−6) with 3-σ confidence. Also including optically thin rotational lines from other molecular species, it is emphasized that systematic errors are ΔV < 1 kms^(−1), corresponding to Δμ/μ < 1.0 × 10^(−6)