The Line Emission Region in III Zw 2: Kinematics and Variability

We have studied the Ly-al, Hbeta, Halpha and Mg II2798 line profiles of the Seyfert 1 galaxy III Zw 2. The shapes of these broad emission lines show evidence of a multicomponent origin and also features which may be identified as the peaks due to a rotating disk. We have proposed a two-component Broad Line Region (BLR) model consisting of an inner Keplerian relativistic disk and an outer structure surrounding the disk. The results of the fitting of the four Broad Emission Lines (BELs) here considered, are highly consistent in both the inner and outer component parameters. Adopting a mass of approx. 2 E8 sollar masses for the central object we found that the outer radius of the disk is approximately equal for the four considered lines (approx 0.01 pc). However, the inner radius of the disk is not the same: 0.0018 pc for Ly-alpha, 0.0027 pc for Mg II, and 0.0038 pc for the Balmer lines. This as well as the relatively broad component present in the blue wings of the narrow [OIII] lines indicate stratification in the emission-line region. Using long-term Hbeta observations (1972-1990, 1998) we found a flux variation of the BEL with respect to the [OIII] lines.Comment: ApJ, accepted, 22 pages, 10 figure

X-ray and Multiwavelength Insights into the Nature of Weak Emission-Line Quasars at Low Redshift

(Abridged) We report on the X-ray and multiwavelength properties of 11 radio-quiet quasars with weak or no emission lines identified by the Sloan Digital Sky Survey (SDSS) with redshift z=0.4-2.5. The distribution of relative X-ray brightness for our low-redshift weak-line quasar (WLQ) candidates is significantly different from that of typical radio-quiet quasars, having an excess of X-ray weak sources, but it is consistent with that of high-redshift WLQs. The X-ray weak sources generally show similar UV emission-line properties to those of the X-ray weak quasar PHL 1811; they may belong to the notable class of PHL 1811 analogs. The average X-ray spectrum of these sources is somewhat harder than that of typical radio-quiet quasars. Several other low-redshift WLQ candidates have normal ratios of X-ray-to-optical/UV flux, and their average X-ray spectral properties are also similar to those of typical radio-quiet quasars. The X-ray weak and X-ray normal WLQ candidates may belong to the same subset of quasars having high-ionization "shielding gas" covering most of the wind-dominated broad emission-line region, but be viewed at different inclinations. The mid-infrared-to-X-ray spectral energy distributions (SEDs) of these sources are generally consistent with those of typical SDSS quasars, showing that they are not likely to be BL Lac objects with relativistically boosted continua and diluted emission lines. However, one source in our X-ray observed sample is remarkably strong in X-rays, indicating that a small fraction of low-redshift WLQ candidates may actually be BL Lacs residing in the radio-faint tail of the BL Lac population. We also investigate universal selection criteria for WLQs over a wide range of redshift, finding that it is not possible to select WLQ candidates in a fully consistent way using different prominent emission lines as a function of redshift.Comment: ApJ in press; 26 pages, 11 figures and 7 tables. The full Table 3 is available upon reques

Genotoxic potential of Cotinus coggygria Scop. (Anacardiaceae) stem extract in vivo

The intention was to evaluate the possible in vivo genotoxic potential in different cell-types, of a methanol extract obtained from the plant stem of Cotinus coggygria Scop., using the sex-linked recessive lethal (or SLRL) test and alkaline comet assay. The SLRL test, revealed the genotoxic effect of this extract in postmeiotic and premeiotic germ-cell lines. The comet assay was carried out on rat liver and bone marrow at 24 and 72 h after intraperitoneal administration. For genotoxic evaluation, three concentrations of the extract were tested, viz., 500, 1000 and 2000 mg/kg body weight (bw), based on the solubility limit of the extract in saline. Comet tail moment and total scores in the group treated with 500 mg/kg bw, 24 and 72 h after treatment, were not significantly different from the control group, whereas in the groups of animals, under the same conditions, but with 1000 and 2000 mg/kg bw of the extract, scores were statistically so. A slight decrease in the comet score and tail moment observed in all the doses in the 72 h treatment, gave to understand that DNA damage induced by Cotinus coggygria extract decreased with time. The results of both tests revealed the genotoxic effect of Cotinus coggygria under our experimental conditions

Optically Selected BL Lacertae Candidates from the Sloan Digital Sky Survey Data Release Seven

We present a sample of 723 optically selected BL Lac candidates from the SDSS DR7 spectroscopic database encompassing 8250 deg^2 of sky; our sample constitutes one of the largest uniform BL Lac samples yet derived. Each BL Lac candidate has a high-quality SDSS spectrum from which we determine spectroscopic redshifts for ~60% of the objects. Redshift lower limits are estimated for the remaining objects utilizing the lack of host galaxy flux contamination in their optical spectra; we find that objects lacking spectroscopic redshifts are likely at systematically higher redshifts. Approximately 80% of our BL Lac candidates match to a radio source in FIRST/NVSS, and ~40% match to a ROSAT X-ray source. The homogeneous multiwavelength coverage allows subdivision of the sample into 637 radio-loud BL Lac candidates and 86 weak-featured radio-quiet objects. The radio-loud objects broadly support the standard paradigm unifying BL Lac objects with beamed radio galaxies. We propose that the majority of the radio-quiet objects may be lower-redshift (z<2.2) analogs to high-redshift weak line quasars (i.e., AGN with unusually anemic broad emission line regions). These would constitute the largest sample of such objects, being of similar size and complementary in redshift to the samples of high-redshift weak line quasars previously discovered by the SDSS. However, some fraction of the weak-featured radio-quiet objects may instead populate a rare and extreme radio-weak tail of the much larger radio-loud BL Lac population. Serendipitous discoveries of unusual white dwarfs, high-redshift weak line quasars, and broad absorption line quasars with extreme continuum dropoffs blueward of rest-frame 2800 Angstroms are also briefly described.Comment: 24 pages, 14 figures, 8 tables. Accepted for publication in A

An Intermediate Luminosity Transient in NGC300: The Eruption of a Dust-Enshrouded Massive Star

[abridged] We present multi-epoch high-resolution optical spectroscopy, UV/radio/X-ray imaging, and archival Hubble and Spitzer observations of an intermediate luminosity optical transient recently discovered in the nearby galaxy NGC300. We find that the transient (NGC300 OT2008-1) has a peak absolute magnitude of M_bol~-11.8 mag, intermediate between novae and supernovae, and similar to the recent events M85 OT2006-1 and SN2008S. Our high-resolution spectra, the first for this event, are dominated by intermediate velocity (~200-1000 km/s) hydrogen Balmer lines and CaII emission and absorption lines that point to a complex circumstellar environment, reminiscent of the yellow hypergiant IRC+10420. In particular, we detect broad CaII H&K absorption with an asymmetric red wing extending to ~1000 km/s, indicative of gas infall onto a massive and relatively compact star (blue supergiant or Wolf-Rayet star); an extended red supergiant progenitor is unlikely. The origin of the inflowing gas may be a previous ejection from the progenitor or the wind of a massive binary companion. The low luminosity, intermediate velocities, and overall similarity to a known eruptive star indicate that the event did not result in a complete disruption of the progenitor. We identify the progenitor in archival Spitzer observations, with deep upper limits from Hubble data. The spectral energy distribution points to a dust-enshrouded star with a luminosity of about 6x10^4 L_sun, indicative of a ~10-20 M_sun progenitor (or binary system). This conclusion is in good agreement with our interpretation of the outburst and circumstellar properties. The lack of significant extinction in the transient spectrum indicates that the dust surrounding the progenitor was cleared by the outburst.Comment: Submitted to ApJ; emulateapj style; 39 pages; 26 figure

LBT and Spitzer Spectroscopy of Star-Forming Galaxies at 1 < z < 3: Extinction and Star Formation Rate Indicators

We present spectroscopic observations in the rest-frame optical and near- to mid-infrared wavelengths of four gravitationally lensed infrared (IR) luminous star-forming galaxies at redshift 1 < z < 3 from the LUCIFER instrument on the Large Binocular Telescope and the Infrared Spectrograph on Spitzer. The sample was selected to represent pure, actively star-forming systems, absent of active galactic nuclei. The large lensing magnifications result in high signal-to-noise spectra that can probe faint IR recombination lines, including Pa-alpha and Br-alpha at high redshifts. The sample was augmented by three lensed galaxies with similar suites of unpublished data and observations from the literature, resulting in the final sample of seven galaxies. We use the IR recombination lines in conjunction with H-alpha observations to probe the extinction, Av, of these systems, as well as testing star formation rate (SFR) indicators against the SFR measured by fitting spectral energy distributions to far-IR photometry. Our galaxies occupy a range of Av from ~0 to 5.9 mag, larger than previously known for a similar range of IR luminosities at these redshifts. Thus, estimates of SFR even at z ~ 2 must take careful count of extinction in the most IR luminous galaxies. We also measure extinction by comparing SFR estimates from optical emission lines with those from far-IR measurements. The comparison of results from these two independent methods indicates a large variety of dust distribution scenarios at 1 < z < 3. Without correcting for dust extinction, the H-alpha SFR indicator underestimates the SFR; the size of the necessary correction depends on the IR luminosity and dust distribution scenario. Individual SFR estimates based on the 6.2 micron PAH emission line luminosity do not show a systematic discrepancy with extinction, although a considerable, ~0.2 dex scatter is observed.Comment: Accepted for publication in The Astrophysical Journal; 14 pages, 8 figure

SDSS J094533.99+100950.1 - the remarkable weak emission line quasar

Weak emission line quasars are a rare and puzzling group of objects. In this paper we present one more object of this class found in the Sloan Digital Sky Survey (SDSS). The quasar SDSS J094533.99+100950.1, lying at z = 1.66, has practically no C IV emission line, a red continuum very similar to the second steepest of the quasar composite spectra of Richards et al., is not strongly affected by absorption and the Mg II line, although relatively weak, is strong enough to measure the black hole mass. The Eddington ratio in this object is about 0.45, and the line properties are not consistent with the trends expected at high accretion rates. We propose that the most probable explanation of the line properties in this object, and perhaps in all weak emission line quasars, is that the quasar activity has just started. A disk wind is freshly launched so the low ionization lines which form close to the disk surface are already observed but the wind has not yet reached the regions where high ionization lines or narrow line components are formed. The relatively high occurrence of such a phenomenon may additionally indicate that the quasar active phase consists of several sub-phases, each starting with a fresh build-up of the Broad Line Region.Comment: 10 pages, 3 figures, 5 tables; accepted for publication in MNRA

The Lick AGN Monitoring Project 2011: Spectroscopic Campaign and Emission-Line Light Curves

In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the AGN continuum, and measurements of the broad H-beta line widths in mean and root-mean square (rms) spectra. For the most highly variable AGNs we also measured broad H-beta line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad H-beta width and luminosity, demonstrating that the broad-line region "breathes" on short timescales of days to weeks in response to continuum variations. We also find that broad H-beta velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593 the broad H-beta velocity shifted by ~250 km/s over a one-month duration. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.Comment: 33 pages, 28 figures, accepted for publication in ApJ Supplement Serie

Plasma Brain-Derived Neurotrophic Factor (BDNF) Concentration and BDNF/TrkB Gene Polymorphisms in Croatian Adults with Asthma

Brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B (TrkB) receptor might contribute to normal lung functioning and immune responses ; however, their role in asthma remains unclear. Plasma BDNF concentrations, as well as BDNF and NTRK2 (TrkB gene) polymorphisms, were investigated in 120 asthma patients and 120 healthy individuals using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively. The genotype and allele frequencies of BDNF Val66Met (rs6265) and NTRK2 rs1439050 polymorphisms did not differ between healthy individuals and asthma patients, nor between patients grouped according to severity or different asthma phenotypes. Although plasma BDNF concentrations were higher among healthy subjects carrying the BDNF Val66Met GG genotype compared to the A allele carriers, such differences were not detected in asthma patients, suggesting the influences of other factors. Plasma BDNF concentration was not affected by NTRK2 rs1439050 polymorphism. Asthma patients had higher plasma BDNF concentrations than control subjects ; however, no differences were found between patients subdivided according to asthma severity, or Type-2, allergic, and eosinophilic asthma. Higher plasma BDNF levels were observed in asthma patients with aspirin sensitivity and aspirin-exacerbated respiratory disease. These results suggest that plasma BDNF may serve as a potential peripheral biomarker for asthma, particularly asthma with aspirin sensitivity

Supernovae and AGN driven galactic outflows

We present analytical solutions for winds from galaxies with NFW dark matter halo. We consider winds driven by energy and mass injection from multiple supernovae, as well as momentum injection due to radiation from a central black hole. We find that the wind dynamics depends on three velocity scales: (a) v_star \sim (\dot{E} / 2 \dot{M})^{1/2} describes the effect of starburst activity, with \dot{E}, \dot{M} as energy and mass injection rate in a central region of radius R; (b) \vbh ~ (G\mbh / 2 R)^{1/2} for the effect of a central black hole of mass \mbh on gas at distance R and (c) v_{s} =(GM_h/ 2Cr_s)^{1/2} which is closely related to the galaxy circular velocity, with C as a function of halo concentration parameter. We find the wind terminal speed to be 2 (v_star^2 +1.5(\Gamma -1) \vbh^2 -v_s^2)^{1/2}, where \Gamma is the ratio of force due to radiation pressure to gravity of the central black hole. We also find that: (a) winds from quiescent star forming galaxies cannot escape from 10^{11.5} \le M_h \le 10^{12.5}Msun galaxies, (b) circumgalactic gas at large distances should be present for galaxies in this mass range, (c) for an escaping wind, the wind speed in low to intermediate mass galaxies is ~ 400--1000 km/s, consistent with observed X-ray temperatures; (d) winds from massive galaxies with AGN have speeds \gtrsim 1000 km/s. We also find that the ratio [2 v_star ^2 -(1 -\Gamma) \vbh^2]/ v_c^2 dictates the amount of gas lost. Used in conjunction with an appropriate relation between \mbh and M_h, and an appropriate opacity of dust grains in IR (K band), this ratio becomes minimum at a certain halo mass scale (M_h ~ 10^{12--12.5} Msun) that signifies the cross-over of AGN domination in outflow properties from starburst activity at lower masses. We find that stellar mass for massive galaxies scales as M_star \propto M_h^{0.26},and for low mass galaxies, M_star \propto M_h^{5/3}.Comment: 20 pages, 6 figures, Accepted in ApJ, Comments Welcom