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Local galaxies from the Sloan Digital Sky Survey (SDSS) are used to provide additional support for an evolutionary pathway in which active galactic nucleus activity is associated with star formation quenching. Composite, Seyfert 2, and LINER galaxies account for ∼60 per cent of all star formation in massive galaxies (M ⋆ > 1010.5 M⊙). Inclusion of these galaxies results in a 'turnover' in the star formation rate and stellar mass (SFR− M ⋆) relation for massive galaxies. Our analysis shows that bulge growth has already occurred in the most massive galaxies (M ⋆ > 1010.5 M⊙), and bulges continue to grow as galaxies quench and redden, (g − r)  = 0.5 → 0.75. Significant bulge growth is also occurring in low mass starburst galaxies (M ⋆ < 1010.5 M⊙) at 0.5 dex above the 'main sequence' (MS), where we find an increase in B/T from 0.1 → 0.3 and bluer colours, (g − r) < 0.25 compared to low-mass galaxies on the MS. [ABSTRACT FROM AUTHOR]

The ultra-luminous infrared galaxy (ULIRG) Mrk 273 contains two infrared nuclei, N and SW, separated by 1 arcsecond. A Chandra observation has identified the SW nucleus as an absorbed X-ray source with NH ∼ 4 x 1023 cm-2 but also hinted at the possible presence of a Compton-thick AGN in the N nucleus, where a black hole of ∼109 M☉ is inferred from the ionized gas kinematics. The intrinsic X-ray spectral slope recently measured by NuSTAR is unusually hard (Г ∼ 1:3) for a Seyfert nucleus, for which we seek an alternative explanation. We hypothesize a strongly absorbed X-ray source in N, of which X-ray emission rises steeply above 10 keV, in addition to the known X-ray source in SW, and test it against the NuSTAR data, assuming the standard spectral slope (Γ = 1:9). This double X-ray source model gives a good explanation of the hard continuum spectrum, deep Fe K absorption edge, and strong Fe K line observed in this ULIRG, without invoking the unusual spectral slope required for a single source interpretation. The putative X-ray source in N is found to be absorbed by NH = 1:4+0:7 -0:4 x 1024 cm-2. The estimated 20-10 keV luminosity of the N source is 1:3 x 1043 erg s-1, about a factor of 2 larger than that of SW during the NuSTAR observation. Uncorrelated variability above and below 10 keV between the Suzaku and NuSTAR observations appears to support the double source interpretation. Variability in spectral hardness and Fe K line flux between the previous X-ray observations is also consistent with this picture. [ABSTRACT FROM AUTHOR]

Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion on to supermassive black holes (SMBHs), giving rise to active galactic nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-selected local luminous and ultraluminous infrared galaxies in different merger stages in the hard X-ray band, where radiation is less affected by absorption, we find that the amount of material around SMBHs increases during the last phases of the merger. We find that the fraction of Compton-thick (CT, NH ≥ 1024 cm- 2) AGN in late-merger galaxies is higher (fCT=65-13+12 percent) than in local hard X-ray selected AGN (fCT = 27 ± 4 per cent), and that obscuration reaches its maximum when the nuclei of the two merging galaxies are at a projected distance of D12 ≃ 0.4-10.8 kpc (fCT=77-17+13percent). We also find that all AGN of our sample in late-merger galaxies have NH > 1023 cm-2, which implies that the obscuring material covers 95-8+4percent of the X-ray source. These observations show that the material is most effectively funnelled from the galactic scale to the inner tens of parsecs during the late stages of galaxy mergers, and that the close environment of SMBHs in advanced mergers is richer in gas and dust with respect to that of SMBHs in isolated galaxies, and cannot be explained by the classical AGN unification model in which the torus is responsible for the obscuration. [ABSTRACT FROM AUTHOR]

The relation between the stellar mass (M*) and the star formation rate (SFR) characterizes how the instantaneous star formation is determined by the galaxy past star formation history and by the growth of the dark matter structures. We deconstruct the M*-SFR plane by measuring the specific SFR functions in several stellar mass bins from z = 0.2 out to z = 1.4 (specific SFR = SFR/M*, noted sSFR). Our analysis is primary based on a 24 μm selected catalogue combining the COSMOS and GOODS surveys. We estimate the SFR by combining mid- and far-infrared data for 20500 galaxies. The sSFR functions are derived in four stellar mass bins within the range 9.5 < log(M*/M☉) < 11.5. First, we demonstrate the importance of taking into account selection effects when studying the M*-SFR relation. Secondly, we find a mass-dependent evolution of the median sSFR with redshift varying as sSFR ∞ (1 + z)b, with b increasing from b = 2.88±0.12 to b = 3.78±0.60 between M* = 109.75 M☉ and M* = 1011.1 M☉, respectively. At low masses, this evolution is consistent with the cosmological accretion rate and predictions from semi-analytical models (SAM). This agreement breaks down for more massive galaxies showing the need for a more comprehensive description of the star formation history in massive galaxies. Third, we obtain that the shape of the sSFR function is invariant with time at z < 1.4 but depends on the mass. We observe a broadening of the sSFR function ranging from 0.28 dex at M* = 109.75 M☉ to 0.46 dex at M* = 1011.1 M☉. Such increase in the intrinsic scatter of the M*-SFR relation suggests an increasing diversity of star formation histories (SFHs) as the stellar mass increases. Finally, we find a gradual decline of the sSFR with stellar mass as log10(sSFR) ∞ -0.17M*.We discuss the numerous physical processes, as gas exhaustion in hot gas halos or secular evolution, which can gradually reduce the sSFR and increase the SFH diversity. [ABSTRACT FROM AUTHOR]

We present an empirical method of assessing the star formation rate (SFR) of star-forming galaxies based on their locations in the rest-frame color-color diagram (NUV - r) vs. (r - K). By using the Spitzer 24 μm sample in the COSMOS field (~16 400 galaxies with 0:2 ⩽ z ⩽ 1:3) and a local GALEX-SDSS-SWIRE sample (~700 galaxies with z ⩽ 0:2), we show that the mean infrared excess hIRXi = hLIR=LUVi can be described by a single vector, NRK, that combines the two colors. The calibration between hIRXi and NRK allows us to recover the IR luminosity, LIR, with an accuracy of σ ~ 0:21 for the COSMOS sample and 0.27 dex for the local one. The SFRs derived with this method agree with the ones based on the observed (UV+IR) luminosities and on the spectral energy distribution (SED) fitting for the vast majority (~85%) of the star-forming population. Thanks to a library of model galaxy SEDs with realistic prescriptions for the star formation history, we show that we need to include a two-component dust model (i.e., birth clouds and di use ISM) and a full distribution of galaxy inclinations in order to reproduce the behavior of the hIRXi stripes in the NUVrK diagram. In conclusion, the NRK method, based only on the rest-frame UV/optical colors available in most of the extragalactic fields, o ers a simple alternative of assessing the SFR of star-forming galaxies in the absence of far-IR or spectral diagnostic observations. [ABSTRACT FROM AUTHOR]

We present a rest-frame spectral stacking analysis of ∼1000 X-ray sources detected in the XMM-COSMOS field to investigate the iron-K line properties of active galaxies beyond redshift z ∼ 1. In Type I AGN that have a typical X-ray luminosity of LX ∼ 1.5 × 1044 (erg s-1) and z ∼ 1.6 the cold Fe K at 6.4 keV is weak (EW ∼ 0.05 keV), which agrees with the known trend. In contrast, high-ionization lines of Fe xxv and Fe xxvi are pronounced. These high-ionization Fe K lines appear to have a connection with high accretion rates. While no broad Fe emission is detected in the total spectrum, it might be present, albeit at low significance (∼2σ), when the X-ray luminosity is restricted to the range below 3 × 1044 erg s-1, or when an intermediate range of Eddington ratio around λ ∼ 0.1 is selected. In Type II AGN, both cold and high-ionzation lines become weak with increasing X-ray luminosity. However, we detected strong high-ionization Fe K (EW ∼ 0.3 keV) in the spectrum of objects at z > 2, while we found no 6.4 keV line. We also found that the primary source of the high-ionization Fe K emission are those objects detected with Spitzer-MIPS at 24 μm. Given their median redshift of z ≃ 2.5, their bolometric luminosity is likely to reach 1013 L☉ and the MIPS-detected emission most likely originates from hot dust heated by embedded AGN, probably accreting at high Eddington ratio. These properties match those of rapidly growing black holes in ultra-luminous infrared galaxies at the interesting epoch (z ∼ 2-3) of galaxy formation. [ABSTRACT FROM AUTHOR]

We investigate the (large-scale) bar fraction in a mass-complete sample of disc galaxies at in the Cosmological Evolution Survey (COSMOS) field. The fraction of barred discs strongly depends on mass, disc morphology and specific star formation rate (SSFR). At intermediate stellar mass the bar fraction in early-type discs is much higher, at all redshifts, by a factor of ∼2, than that in late-type discs. This trend is reversed at higher stellar mass , where the fraction of bars in early-type discs becomes significantly lower, at all redshifts, than that in late-type discs. The bar fractions for galaxies with low and high SSFRs closely follow those of the morphologically selected early- and late-type populations, respectively. This indicates a close correspondence between morphology and SSFR in disc galaxies at these earlier epochs. Interestingly, the total bar fraction in discs is built up by a factor of ∼2 over the redshift interval explored, while for discs it remains roughly constant. This indicates that, already by , spectral and morphological transformations in the most massive disc galaxies have largely converged to the familiar Hubble sequence that we observe in the local Universe, while for intermediate-mass discs this convergence is ongoing until at least . Moreover, these results highlight the importance of employing mass-limited samples for quantifying the evolution of barred galaxies. Finally, the evolution of the barred galaxy populations investigated does not depend on the large-scale environmental density (at least, on the scales which can be probed with the available photometric redshifts). [ABSTRACT FROM AUTHOR]

We report an overdensity of bright submillimetre galaxies (SMGs) in the 0.15 deg2 AzTEC/COSMOS survey and a spatial correlation between the SMGs and the optical-IR galaxy density at . This portion of the COSMOS field shows a overdensity of robust SMG detections when compared to a background, or ‘blank-field’, population model that is consistent with SMG surveys of fields with no extragalactic bias. The SMG overdensity is most significant in the number of very bright detections (14 sources with measured fluxes mJy), which is entirely incompatible with sample variance within our adopted blank-field number densities and infers an overdensity significance of . We find that the overdensity and spatial correlation to optical-IR galaxy density are most consistent with lensing of a background SMG population by foreground mass structures along the line of sight, rather than physical association of the SMGs with the galaxies/clusters. The SMG positions are only weakly correlated with weak-lensing maps, suggesting that the dominant sources of correlation are individual galaxies and the more tenuous structures in the survey region, and not the massive and compact clusters. These results highlight the important roles cosmic variance and large-scale structure can play in the study of SMGs. [ABSTRACT FROM AUTHOR]

We present a 1.1 mm wavelength imaging survey covering 0.3 deg2 in the COSMOS field. These data, obtained with the AzTEC continuum camera on the James Clerk Maxwell Telescope, were centred on a prominent large-scale structure overdensity which includes a rich X-ray cluster at z≈ 0.73. A total of 50 mm-galaxy candidates, with a significance ranging from 3.5 to 8.5σ, are extracted from the central 0.15 deg2 area which has a uniform sensitivity of ∼1.3 mJy beam−1. 16 sources are detected with S/N ≥ 4.5, where the expected false-detection rate is zero, of which a surprisingly large number (9) have intrinsic (deboosted) fluxes ≥5 mJy at 1.1 mm. Assuming the emission is dominated by radiation from dust, heated by a massive population of young, optically obscured stars, then these bright AzTEC sources have far-infrared luminosities and star formation rates . Two of these nine bright AzTEC sources are found towards the extreme peripheral region of the X-ray cluster, whilst the remainder are distributed across the larger scale overdensity. We describe the AzTEC data reduction pipeline, the source-extraction algorithm, and the characterization of the source catalogue, including the completeness, flux deboosting correction, false-detection rate and the source positional uncertainty, through an extensive set of Monte Carlo simulations. We conclude with a preliminary comparison, via a stacked analysis, of the overlapping MIPS 24-μm data and radio data with this AzTEC map of the COSMOS field. [ABSTRACT FROM AUTHOR]

Prominent Fe Kα line emission is detected in theXMM–Newtonspectrum of the ultraluminous infrared galaxy Arp 220. The centroid of the line is found at an energy of 6.7 keV and the equivalent width of the line is(at 3.5σ significance). A few other spectral features are found at various degrees of significance in the lower energy range on a hard 2.5–10 keV continuum. The large EW of the Fe K line poses a problem with interpreting the hard X-ray emission as integrated X-ray binary emission. A thermal emission spectrum with a temperature ofmodified by absorption of, can describe the 2.5–10 keV continuum shape and the Fe K emission. A hot bubble that is shocked internally in a starburst region would have a similar temperature and gives a good explanation for the observed X-ray properties with a high star formation rate. An ensemble of radio supernovae in a dense environment, as suggested from VLBI imaging, could be another possibility, if such powerful supernovae are produced continuously at a high rate. However, the apparent lack of emission from X-ray binaries is incompatible with the high supernova rate (∼2 SNe yr−1) required by both interpretations. Highly photoionized, low-density gas illuminated by a hidden Compton-thick active galactic nucleus is a possible alternative for the hard X-ray emission, which can be tested by examining whether radiative recombination continua from highly ionized Ca and Fe are present in better quality data from a forthcoming observation. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to compare results of electromyographic assessment of muscular recruitment between nulliparous control subjects without pelvic floor dysfunction and parous subjects with genuine stress urinary incontinence and with pelvic organ prolapse. Interference pattern analysis is an electromyographic technique that reproducibly measures muscular recruitment by detecting both "turns" in the electromyographic signal produced by positive and negative peaks of the motor unit potentials and motor unit potential amplitude. Fewer turns can indicate loss of motor units or failure of central activation of contraction, whereas greater amplitude can indicate reinnervation after nerve damage.Study Design: We performed concentric needle electrode electromyographic examinations of the levator ani and external anal sphincter in 15 nulliparous control subjects and 20 parous subjects with abnormalities (n = 9 with genuine stress urinary incontinence, n = 11 with stage III or IV pelvic organ prolapse). We made digital recordings at multiple sites at rest and with moderate and maximal contraction. Interference pattern analysis yielded the number of turns per second and the mean signal amplitude (in microvolts) for each site at each contraction level. We compared individual patient data with data from the healthy population by means of cloud analysis. Mean values of number of turns per second and mean amplitude in each group were then compared with nonparametric methods and regression models.Results: Mean ages were 28.7 years (range, 20-49 years) for the control group, 54.3 years (range, 35-75 years) for subjects with genuine stress urinary incontinence, and 65 years (range, 41-77 years) for subjects with pelvic organ prolapse. Median clinical levator ani strengths were 9 (range, 5-9) in the control group, 5 (range, 2-7) in the genuine stress urinary incontinence group, and 5 (range, 2-8) in the pelvic organ prolapse group. Median external anal sphincter strengths were 9 (range, 7-9) in the control group, 5 (range, 3-9) in the genuine stress urinary incontinence group, and 8 (range, 4-9) in the pelvic organ prolapse group. The external anal sphincters of subjects with pelvic organ prolapse had the highest percentage of abnormal study results according to cloud analysis. Mean number of turns per second in levators was greater in control subjects than in subjects with abnormalities (P =.034). We found similar differences in number of turns per second for the external anal sphincter (P =.004). In contrast, we did not find differences between groups in mean amplitude in either the levator ani or the external anal sphincter. Comparison of patients with genuine stress urinary incontinence versus subjects with pelvic organ prolapse showed no significant difference in the number of turns per second in either muscle. Mean amplitude was greater in the pelvic organ prolapse group than in the genuine stress urinary incontinence group for both muscles (levator ani, P =.028; external anal sphincter, P =.048). Neither mean amplitude nor the number of turns per second could be predicted by clinically estimated levator ani strength, age, or fecal incontinence.Conclusion: Compared with nulliparous control subjects, patients with genuine stress urinary incontinence and pelvic organ prolapse had changes in the levator ani and external anal sphincter consistent with either motor unit loss or failure of central activation, or both. Subjects with pelvic organ prolapse had findings consistent with greater recovery than was found in those with genuine stress urinary incontinence. Measures of recruitment by interference pattern analysis correlated better with clinical external anal sphincter strength than with levator ani strength and were independent of age. [ABSTRACT FROM AUTHOR]

Objectives: Our aims were to introduce a method of digital quantitative electromyography of the levator ani and external anal sphincter muscles and to establish reference values.Study Design: Fifteen nulliparous, symptom-free women underwent concentric needle electromyographic examination of the levator ani and external anal sphincter. We sampled the levator ani transvaginally at 4 sites and the external anal sphincter at 2 sites. The signal was filtered and amplified, and digital recordings were made at 3 levels of voluntary activation at each site. Analyses of motor unit action potentials and interference patterns were performed with the use of these taped signals. Normal ranges were generated and compared with those established for other striated muscles.Results: The mean age of the subjects was 28.7+/-7.5 years. A median of 24 motor unit action potentials was recorded in each levator ani, and a median of 6 was recorded in each external anal sphincter. Parameters of the levator ani action potentials were significantly greater than those of the external anal sphincter in amplitude (0.48 vs. 0.37 mV; P =.001), duration (10.40 vs. 8.27 ms; P =.002), number of turns per second (2. 80 vs. 2.28; P<.001), and area (0.65 vs. 0.36; P<.001). Parameters of the interference patterns were significantly greater in the levator ani than in the external anal sphincter in number of turns per second (241.6 vs. 183.9; P =.015), amplitude (302.7 vs. 225.3 microV; P<.0001), activity (95.6 vs 61.2; P =.004), envelope size (861.1 vs 567.6 microV; P<.0001), and number of small segments (105. 8 vs 81.4; P =.047). There were no significant differences between levator ani, external anal sphincter, and published parameters from the biceps muscle with regard to amplitude and duration of motor unit action potentials.Conclusions: Electromyography of the levator ani and external anal sphincter is feasible and well tolerated. Our findings confirm that the levator ani muscle has larger, more readily recruited motor units than does the external anal sphincter. Ranges for important quantitative electromyographic parameters for these muscles are similar to those published for the biceps. [ABSTRACT FROM AUTHOR]

At luminosities above 10[sup 11] , infrared galaxies become the dominant population of extragalactic objects in the local Universe (z <= 0.3), being more numerous than optically selected starburst and Seyfert galaxies and quasi-stellar objects at comparable bolometric luminosity. The trigger for the intense infrared emission appears to be the strong interaction/merger of molecular gas-rich spirals, and the bulk of the infrared luminosity for all but the most luminous objects is due to dust heating from an intense starburst within giant molecular clouds. At the highest luminosities (Lir > 10[sup 12] ), nearly all objects appear to be advanced mergers powered by a mixture of circumnuclear starburst and active galactic nucleus energy sources, both of which are fueled by an enormous concentration of molecular gas that has been funneled into the merger nucleus. These ultraluminous infrared galaxies may represent an important stage in the formation of quasi-stellar objects and powerful radio galaxies. They may also represent a primary stage in the formation of elliptical galaxy cores, the formation of globular clusters, and the metal enrichment of the intergalactic medium. [ABSTRACT FROM AUTHOR]

A modified line source model was used to simulate single muscle fibre action potentials and their radial decline as measured using a single fibre (SF), concentric needle (CN) and macroelectromyography (EMG) electrode. The 90 per cent attenuation distance, defined as the distance from the fibre at which the peak-to-peak amplitude of the action potential declines to 10 per cent of its value measured near the fibre, was determined. For the CN and macro electrode this distance was 1·4 and 4·1 times, respectively, the distance measured for the SF electrode Based on the decline characteristics obtained from our simulations and experimental data reported in the literature, we inferred that in a normal human biceps muscle the spike component of CN MUAPs is produced mainly by the action potentials of the closest one-six muscle fibres. This inference was used to interpret the changes in MUAP amplitude seen by clinical EMG in neuromuscular diseases. The decline of action potential amplitude with distance from the electrode was least when recordings were made by the macro-EMG electrode. The three electrodes differed in their uptake area and thus recordings made with them provided complementary information about the motor unit architecture and the way it changes in neuromuscular diseases. [ABSTRACT FROM AUTHOR]

In a patient with the Eaton-Lambert syndrome, 4-aminopyridine produced temporary improvement of clinical and electromyographic abnormalities. Application of the drug in vitro to intercostal muscle from the patient produced an increase in the evoked release of neurotransmitter from intramuscular nerves. [ABSTRACT FROM AUTHOR]