13CO(J=1−−0)^{13}CO(J = 1 -- 0) Depression in Luminous Starburst Mergers

It is known that the class of luminous starburst galaxies tends to have higher $R =^{12}CO(J=1--0)/^{13}CO(J=1--0)$ integrated line intensity ratios ($R>20$) than normal spiral galaxies ($R \sim 10$). Since most previous studies investigated only $R$, it remains uncertain whether the luminous starburst galaxies are overabundant in $^{12}$CO or underabundant in $^{13}$CO. Here we propose a new observational test to examine this problem. Our new test is to compare far-infrared luminosities [$L$(FIR)] with those of $^{12}$CO and $^{13}CO [L(^{12}CO)$ and $L(^{13}CO)$, respectively]. It is shown that there is a very tight correlation between $L(^{12}CO)$ and L(FIR), as found in many previous studies. However, we find that the $^{13}$CO luminosities of the high-R galaxies are lower by a factor of three on the average than those expected from the correlation for the remaining galaxies with ordinary $R$ values. Therefore, we conclude that the observed high $R$ values for the luminous starburst galaxies are attributed to their lower $^{13}$CO line intensities.Comment: 9 pages (aaspp4.sty), 3 postscript figures (embedded). Accepted for publication in Astrophysical Journal Letter

A Review on the Extension of Hall’s Method of Quantification to Bulk Specimen X-Ray Microanalysis

The theoretical background and the experimental data described in this paper justify the application of the Hall\u27s continuum method of quantitation and the use of bulk crystals of known composition as standards, without ZAF correction, for the biological bulk specimen X-ray microanalysis, provided that proper criteria are respected during the realization of such measurements. The most important points are as follows: (i) Only crystals can be selected where the electrostatic charging is negligible or absent. This depends in part on the own characteristics of the crystals, and can also be facilitated by using low accelerating voltage, e.g. 10 kV, well-conducting specimen holders, and fast scanning rates; (ii) Apart from the element of interest (Na, K, Cl, etc.) all other accompanying components must be of low atomic number (11 or lower), in order to assure the similarity to the composition of the biological matrix where C, O, N and H are the most abundant elements. Comparison of the results in brain and liver cell nuclei and cytoplasm revealed that the elemental concentrations of Na and K are identical within the statistical scatter, if the continuum radiation used for the calculation of the peak-to-background ratios is selected under the respective elemental peak, or farther, in a peak-free region of the spectrum

Effect of a cognitive training program on the platelet app ratio in patients with alzheimer’s disease

In patients with Alzheimer’s disease (AD), synaptic plasticity seems to be involved in cognitive improvement induced by cognitive training. The platelet amyloid precursor protein (APP) ratio (APPr), i.e., the ratio between two APP isoforms, may be a useful peripheral biomarker to investigate synaptic plasticity pathways. This study evaluates the changes in neuropsychological/cognitive performance and APPr induced by cognitive training in AD patients participating in the “My Mind Project”. Neuropsychological/cognitive variables and APPr were evaluated in the trained group (n = 28) before a two-month experimental protocol, immediately after its termination at follow-up 1 (FU1), after 6 months at follow-up 2 (FU2), and after 24 months at follow-up 3 (FU3). The control group (n = 31) received general psychoeducational training for two months. Some memory and attention parameters were significantly improved in trained vs. control patients at FU1 and FU2 compared to baseline (∆ values). At FU3, APPr and Mini Mental State Examination (MMSE) scores decreased in trained patients. ∆ APPr correlated significantly with the ∆ scores of (i) MMSE at FU1, (ii) the prose memory test at FU2, and (iii) Instrumental Activities of Daily Living (IADL), the semantic word fluency test, Clinical Dementia Rating (CDR), and the attentive matrices test at FU3. Our data demonstrate that the platelet APPr correlates with key clinical variables, thereby proving that it may be a reliable biomarker of brain function in AD patients

Atomic Carbon in Galaxies

We present new measurements of the ground state fine-structure line of atomic carbon at 492 GHz in a variety of nearby external galaxies, ranging from spiral to irregular, interacting and merging types. In comparison with CO(1-0), the CI(1-0) intensity stays fairly comparable in the different environments, with an average value of the ratio of the line integrated areas in Kkm/s of CI(1-0)/CO(1-0) = 0.2 +/- 0.2. However, some variations can be found within galaxies, or between galaxies. Relative to CO lines, CI(1-0) is weaker in galactic nuclei, but stronger in disks, particularly outside star forming regions. Also, in NGC 891, the CI(1-0) emission follows the dust continuum at 1.3mm extremely well along the full length of the major axis where molecular gas is more abundant than atomic gas. Atomic carbon therefore appears to be a good tracer of molecular gas in external galaxies, possibly more reliable than CO. Atomic carbon can contribute significantly to the thermal budget of interstellar gas. Cooling due to C and CO amounts typically to 2 x 10^{-5} of the FIR continuum or 5% of the CII line. However, C and CO cooling reaches 30% of the gas total, in Ultra Luminous InfraRed Galaxies, where CII is abnormally faint. Together with CII/FIR, the emissivity ratio CI(1-0)/FIR can be used as a measure of the non-ionizing UV radiation field in galaxies.Comment: 26 pages, 8 figure

Detection of water at z = 0.685 towards B0218+357

We report the detection of the H_2O molecule in absorption at a redshift z = 0.68466 in front of the gravitationally lensed quasar B0218+357. We detect the fundamental transition of ortho-water at 556.93 GHz (redshifted to 330.59 GHz). The line is highly optically thick and relatively wide (15 km/s FWHM), with a profile that is similar to that of the previously detected CO(2--1) and HCO^+(2--1) optically thick absorption lines toward this quasar. From the measured level of the continuum at 330.59 GHz, which corresponds to the level expected from the power-law spectrum $S(\nu) \propto \nu^{-0.25}$ already observed at lower frequencies, we deduce that the filling factor of the H_2O absorption is large. It was already known from the high optical thickness of the CO, ^{13}CO and C^{18}O lines that the molecular clouds entirely cover one of the two lensed images of the quasar (all its continuum is absorbed); our present results indicate that the H_2O clouds are covering a comparable surface. The H_2O molecules are therefore not confined to small cores with a tiny filling factor, but are extended over parsec scales. The H_2O line has a very large optical depth, and only isotopic lines could give us the water abundance. We have also searched for the 183 GHz line in absorption, obtaining only an upper limit; this yields constraints on the excitation temperature.Comment: 4 pages, 3 figures, accepted in ApJ Letter

A Survey of Merger Remnants II: The Emerging Kinematic and Photometric Correlations

This paper is the second in a series exploring the properties of 51 {\it optically} selected, single-nuclei merger remnants. Spectroscopic data have been obtained for a sub-sample of 38 mergers and combined with previously obtained infrared photometry to test whether mergers exhibit the same correlations as elliptical galaxies among parameters such as stellar luminosity and distribution, central stellar velocity dispersion ($\sigma$$_{\circ}$), and metallicity. Paramount to the study is to test whether mergers lie on the Fundamental Plane. Measurements of $\sigma$$_{\circ}$ have been made using the Ca triplet absorption line at 8500 {\AA} for all 38 mergers in the sub-sample. Additional measurements of $\sigma$$_{\circ}$ were made for two of the mergers in the sub-sample using the CO absorption line at 2.29 \micron. The results indicate that mergers show a strong correlation among the parameters of the Fundamental Plane but fail to show a strong correlation between $\sigma$$_{\circ}$ and metallicity (Mg$_{2}$). In contrast to earlier studies, the $\sigma$$_{\circ}$ of the mergers are consistent with objects which lie somewhere between intermediate-mass and luminous giant elliptical galaxies. However, the discrepancies with earlier studies appears to correlate with whether the Ca triplet or CO absorption lines are used to derive $\sigma$$_{\circ}$, with the latter almost always producing smaller values. Finally, the photometric and kinematic data are used to demonstrate for the first time that the central phase-space density of mergers are equivalent to elliptical galaxies. This resolves a long-standing criticism of the merger hypothesis.Comment: Accepted Astronomical Journal (to appear in January 2006

The Host Galaxies of Optical Bright QSOs: Molecular Gas in Z < 0.1 PG-QSOs

We present results of a CO(1-0) line survey in a complete sample of 12 low redshift (Z < 0.1), optically bright QSOs (PG QSOs with M_B < -23 mag). Six new CO detections are reported here at levels exceeding I_CO ~2 Jy km/s. Combined with three previously reported detections, we find that 9 of the 12 QSOs have abundant, dense ISMs characteristic of late type galaxies. In all 9 of the detected QSOs, the derived molecular gas masses are M(H2) > 1.0e9 M_solar, with the most massive being 1e10 M_solar ~(PG 0050+124 -- I Zw 1). In the three sources not yet detected in CO, the upper limits on the gas masses are ~ 1e9 M_solar and thus we cannot rule out abundant ISMs even in these objects. Since our sample was chosen entirely on the basis of low redshift and optical luminosity (and not selected for strong infrared emission), we conclude that the majority of luminous, low redshift QSOs have gas-rich host galaxies and therefore can not be normal elliptical galaxies.Comment: 13 pages, 2 figures, submitted to ApJ Letter

Spherical Infall in G10.6-0.4: Accretion Through an Ultracompact HII Region

We present high resolution (0.''12 x 0.''079) observations of the ultracompact HII region G10.6-0.4 in 23 GHz radio continuum and the NH3(3,3) line. Our data show that the infall in the molecular material is largely spherical, and does not flatten into a molecular disk at radii as small as 0.03 pc. The spherical infall in the molecular gas matches in location and velocity the infall seen in the ionized gas. We use a non-detection to place a stringent upper limit on the mass of an expanding molecular shell associated with pressure driven expansion of the HII region. These data support a scenario in which the molecular accretion flow passes through an ionization front and becomes an ionized accretion flow onto one or more main sequence stars, not the classical pressure-driven expansion scenario. In the continuum emission we see evidence for externally ionized clumps of molecular gas, and cavities evacuated by an outflow from the central source.Comment: Accepted for publication in Astrophysical Journal Letter

Atomic Carbon in APM 08279+5255 at z=3.91

We present a detection of [CI] line emission in the lensed quasar APM 08279+5255 at z=3.91 using the IRAM Plateau de Bure interferometer. The [CI] line velocity and width are similar to the values of previously detected high-J CO and HCN lines in this source, suggesting that the emission from all of these species arises from the same region. The apparent luminosity of the [CI] line is L'(CI) = (3.1 +/- 0.4)x10^10 K km/s pc^2, which implies a neutral carbon mass, M(CI) = (4.4+/-0.6)/m x10^7 M_sun, where m is the lensing magnification factor. The [CI] line luminosity is consistent with the large molecular gas mass inferred from the nuclear CO line luminosity ~10^11 /m M_sun. We also present an upper limit on the H2O line luminosity in APM 08279+5255 of, L'(H2O) < 1.8x10^10 K km/s pc^2 (3-sigma).Comment: Accepted for publication in the Astrophysical Journa

A Prediction of Brown Dwarfs in Ultracold Molecular Gas

A recent model for the stellar initial mass function (IMF), in which the stellar masses are randomly sampled down to the thermal Jeans mass from hierarchically structured pre-stellar clouds, predicts that regions of ultra-cold CO gas, such as those recently found in nearby galaxies by Allen and collaborators, should make an abundance of Brown Dwarfs with relatively few normal stars. This result comes from the low value of the thermal Jeans mass, considering that the hierarchical cloud model always gives the Salpeter IMF slope above this lower mass limit. The ultracold CO clouds in the inner disk of M31 have T~3K and pressures that are probably 10 times higher than in the solar neighborhood. This gives a mass at the peak of the IMF equal to 0.01 Msun, well below the Brown Dwarf limit of 0.08 Msun. Using a functional approximation to the IMF, the ultracold clouds would have 50% of the star-like mass and 90% of the objects below the Brown Dwarf limit. The brightest of the Brown Dwarfs in M31 should have an apparent, extinction-corrected K-band magnitude of ~21 mag in their pre-main sequence phase.Comment: 13 pages, 2 figures, to be published in Astrophysical Journal, Vol 522, September 10, 199