9 research outputs found

    ALMA Observations of the Submillimeter Dense Molecular Gas Tracers in the Luminous Type-1 Active Nucleus of NGC 7469

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    We present ALMA Cycle 1 observations of the central kpc region of the luminous type-1 Seyfert galaxy NGC 7469 with unprecedented high resolution (0.5"" ×\times 0.4"" = 165 pc ×\times 132 pc) at submillimeter wavelengths. Utilizing the wide-bandwidth of ALMA, we simultaneously obtained HCN(4-3), HCO+^+(4-3), CS(7-6), and partially CO(3-2) line maps, as well as the 860 μ\mum continuum. The region consists of the central ∼\sim 1"" component and the surrounding starburst ring with a radius of ∼\sim 1.5""-2.5"". Several structures connect these components. Except for CO(3-2), these dense gas tracers are significantly concentrated towards the central ∼\sim 1"", suggesting their suitability to probe the nuclear regions of galaxies. Their spatial distribution resembles well those of centimeter and mid-infrared continuum emissions, but it is anti-correlated with the optical one, indicating the existence of dust obscured star formation. The integrated intensity ratios of HCN(4-3)/HCO+^+(4-3) and HCN(4-3)/CS(7-6) are higher at the AGN position than at the starburst ring, which is consistent to our previous findings (submm-HCN enhancement). However, the HCN(4-3)/HCO+^+(4-3) ratio at the AGN position of NGC 7469 (1.11±\pm0.06) is almost half of the corresponding value of the low-luminosity type-1 Seyfert galaxy NGC 1097 (2.0±\pm0.2), despite the more than two orders of magnitude higher X-ray luminosity of NGC 7469. But the ratio is comparable to that of the close vicinity of the AGN of NGC 1068 (∼\sim 1.5). Based on these results, we speculate that some other heating mechanisms than X-ray (e.g., mechanical heating due to AGN jet) can contribute significantly for shaping the chemical composition in NGC 1097.Comment: Fixed typos in the title. 15 pages, 8 figures, 4 tables: accepted for publication in ApJ. Comments welcom

    Protective Effect of Ferulic Acid against Hydrogen Peroxide Induced Apoptosis in PC12 Cells

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    Ferulic Acid (FA) is a highly abundant phenolic phytochemical which is present in plant tissues. FA has biological effects on physiological and pathological processes due to its anti-apoptotic and anti-oxidative properties, however, the detailed mechanism(s) of function is poorly understood. We have identified FA as a molecule that inhibits apoptosis induced by hydrogen peroxide (H2O2) or actinomycin D (ActD) in rat pheochromocytoma, PC12 cell. We also found that FA reduces H2O2-induced reactive oxygen species (ROS) production in PC12 cell, thereby acting as an anti-oxidant. Then, we analyzed FA-mediated signaling responses in rat pheochromocytoma, PC12 cells using antibody arrays for phosphokinase and apoptosis related proteins. This FA signaling pathway in PC12 cells includes inactivation of pro-apoptotic proteins, SMAC/Diablo and Bad. In addition, FA attenuates the cell injury by H2O2 through the inhibition of phosphorylation of the extracellular signal-regulated kinase (ERK). Importantly, we find that FA restores expression levels of brain-derived neurotrophic factor (BDNF), a key neuroprotective effector, in H2O2-treated PC12 cells. As a possible mechanism, FA increases BDNF by regulating microRNA-10b expression following H2O2 stimulation. Taken together, FA has broad biological effects as a neuroprotective modulator to regulate the expression of phosphokinases, apoptosis-related proteins and microRNAs against oxidative stress in PC12 cells
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