2,854 research outputs found

    Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. V. A New Size-Luminosity Scaling Relation for the Broad-Line Region

    Full text link
    This paper reports results of the third-year campaign of monitoring super-Eddington accreting massive black holes (SEAMBHs) in active galactic nuclei (AGNs) between 2014-2015. Ten new targets were selected from quasar sample of Sloan Digital Sky Survey (SDSS), which are generally more luminous than the SEAMBH candidates in last two years. Hβ\beta lags (τHβ\tau_{_{\rm H\beta}}) in five of the 10 quasars have been successfully measured in this monitoring season. We find that the lags are generally shorter, by large factors, than those of objects with same optical luminosity, in light of the well-known RHβL5100R_{_{\rm H\beta}}-L_{5100} relation. The five quasars have dimensionless accretion rates of M˙=10103\dot{\mathscr{M}}=10-10^3. Combining measurements of the previous SEAMBHs, we find that the reduction of Hβ\beta lags tightly depends on accretion rates, τHβ/τRLM˙0.42\tau_{_{\rm H\beta}}/\tau_{_{R-L}}\propto\dot{\mathscr{M}}^{-0.42}, where τRL\tau_{_{R-L}} is the Hβ\beta lag from the normal RHβL5100R_{_{\rm H\beta}}-L_{5100} relation. Fitting 63 mapped AGNs, we present a new scaling relation for the broad-line region: RHβ=α144β1min[1,(M˙/M˙c)γ1]R_{_{\rm H\beta}}=\alpha_1\ell_{44}^{\beta_1}\,\min\left[1,\left(\dot{\mathscr{M}}/\dot{\mathscr{M}}_c\right)^{-\gamma_1}\right], where 44=L5100/1044erg s1\ell_{44}=L_{5100}/10^{44}\,\rm erg~s^{-1} is 5100 \AA\ continuum luminosity, and coefficients of α1=(29.62.8+2.7)\alpha_1=(29.6_{-2.8}^{+2.7}) lt-d, β1=0.560.03+0.03\beta_1=0.56_{-0.03}^{+0.03}, γ1=0.520.16+0.33\gamma_1=0.52_{-0.16}^{+0.33} and M˙c=11.196.22+2.29\dot{\mathscr{M}}_c=11.19_{-6.22}^{+2.29}. This relation is applicable to AGNs over a wide range of accretion rates, from 10310^{-3} to 10310^3. Implications of this new relation are briefly discussed.Comment: 15 pages, 9 figures, 5 table, accepted for publication in The Astrophysical Journa

    A Unified Approach to the Classical Statistical Analysis of Small Signals

    Get PDF
    We give a classical confidence belt construction which unifies the treatment of upper confidence limits for null results and two-sided confidence intervals for non-null results. The unified treatment solves a problem (apparently not previously recognized) that the choice of upper limit or two-sided intervals leads to intervals which are not confidence intervals if the choice is based on the data. We apply the construction to two related problems which have recently been a battle-ground between classical and Bayesian statistics: Poisson processes with background, and Gaussian errors with a bounded physical region. In contrast with the usual classical construction for upper limits, our construction avoids unphysical confidence intervals. In contrast with some popular Bayesian intervals, our intervals eliminate conservatism (frequentist coverage greater than the stated confidence) in the Gaussian case and reduce it to a level dictated by discreteness in the Poisson case. We generalize the method in order to apply it to analysis of experiments searching for neutrino oscillations. We show that this technique both gives correct coverage and is powerful, while other classical techniques that have been used by neutrino oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with published version. A few small changes, plus the two substantive changes we made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C). It was inconsistent with our actual definition in Sec. VI. 2) "Note added in proof" at end of the Conclusio

    Evidence for e+eγχc1,2e^+e^-\to\gamma\chi_{c1, 2} at center-of-mass energies from 4.009 to 4.360 GeV

    Full text link
    Using data samples collected at center-of-mass energies of s\sqrt{s} = 4.009, 4.230, 4.260, and 4.360 GeV with the BESIII detector operating at the BEPCII collider, we perform a search for the process e+eγχcJe^+e^-\to\gamma\chi_{cJ} (J=0,1,2)(J = 0, 1, 2) and find evidence for e+eγχc1e^+e^-\to\gamma\chi_{c1} and e+eγχc2e^+e^-\to\gamma\chi_{c2} with statistical significances of 3.0σ\sigma and 3.4σ\sigma, respectively. The Born cross sections σB(e+eγχcJ)\sigma^{B}(e^+e^-\to\gamma\chi_{cJ}), as well as their upper limits at the 90% confidence level are determined at each center-of-mass energy.Comment: 8 pages, 7 figures, 3 table

    Observation of χc1\chi_{c1} decays into vector meson pairs ϕϕ\phi\phi, ωω\omega\omega, and ωϕ\omega\phi

    Get PDF
    Decays of χc1\chi_{c1} to vector meson pairs ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi are observed for the first time using (106±4)×106(106\pm4)\times 10^6 \psip events accumulated at the BESIII detector at the BEPCII e+ee^+e^- collider. The branching fractions are measured to be (4.4±0.3±0.5)×104(4.4\pm 0.3\pm 0.5)\times 10^{-4}, (6.0±0.3±0.7)×104(6.0\pm 0.3\pm 0.7)\times 10^{-4}, and (2.2±0.6±0.2)×105(2.2\pm 0.6\pm 0.2)\times 10^{-5}, for χc1ϕϕ\chi_{c1}\to \phi\phi, ωω\omega\omega, and ωϕ\omega\phi, respectively. The observation of χc1\chi_{c1} decays into a pair of vector mesons ϕϕ\phi\phi, ωω\omega\omega and ωϕ\omega\phi indicates that the hadron helicity selection rule is significantly violated in χcJ\chi_{cJ} decays. In addition, the measurement of χcJωϕ\chi_{cJ}\to \omega\phi gives the rate of doubly OZI-suppressed decay. Branching fractions for χc0\chi_{c0} and χc2\chi_{c2} decays into other vector meson pairs are also measured with improved precision.Comment: 4 pages, 2 figure

    Genome-wide association study of endometrial cancer in E2C2

    Get PDF
    Endometrial cancer (EC), a neoplasm of the uterine epithelial lining, is the most common gynecological malignancy in developed countries and the fourth most common cancer among US women. Women with a family history of EC have an increased risk for the disease, suggesting that inherited genetic factors play a role. We conducted a two-stage genome-wide association study of Type I EC. Stage 1 included 5,472 women (2,695 cases and 2,777 controls) of European ancestry from seven studies. We selected independent single-nucleotide polymorphisms (SNPs) that displayed the most significant associations with EC in Stage 1 for replication among 17,948 women (4,382 cases and 13,566 controls) in a multiethnic population (African America, Asian, Latina, Hawaiian and European ancestry), from nine studies. Although no novel variants reached genome-wide significance, we replicated previously identified associations with genetic markers near the HNF1B locus. Our findings suggest that larger studies with specific tumor classification are necessary to identify novel genetic polymorphisms associated with EC susceptibility. Electronic supplementary material The online version of this article (doi:10.1007/s00439-013-1369-1) contains supplementary material, which is available to authorized users

    Improved measurement of the absolute branching fraction of D+Kˉ0μ+νμD^{+}\rightarrow \bar K^0 \mu^{+}\nu_{\mu}

    Get PDF
    By analyzing 2.93 fb1^{-1} of data collected at s=3.773\sqrt s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction B(D+Kˉ0μ+νμ)=(8.72±0.07stat.±0.18sys.)%{\mathcal B}(D^{+}\rightarrow\bar K^0\mu^{+}\nu_{\mu})=(8.72 \pm 0.07_{\rm stat.} \pm 0.18_{\rm sys.})\%, which is consistent with previous measurements within uncertainties but with significantly improved precision. Combining the Particle Data Group values of B(D0Kμ+νμ){\mathcal B}(D^0\to K^-\mu^+\nu_\mu), B(D+Kˉ0e+νe){\mathcal B}(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e}), and the lifetimes of the D0D^0 and D+D^+ mesons with the value of B(D+Kˉ0μ+νμ){\mathcal B}(D^{+}\rightarrow\bar K^0 \mu^{+}\nu_{\mu}) measured in this work, we determine the following ratios of partial widths: Γ(D0Kμ+νμ)/Γ(D+Kˉ0μ+νμ)=0.963±0.044\Gamma(D^0\to K^-\mu^+\nu_\mu)/\Gamma(D^{+}\rightarrow\bar K^0\mu^{+}\nu_{\mu})=0.963\pm0.044 and Γ(D+Kˉ0μ+νμ)/Γ(D+Kˉ0e+νe)=0.988±0.033\Gamma(D^{+}\rightarrow\bar K^0 \mu^{+}\nu_{\mu})/\Gamma(D^{+}\rightarrow\bar K^0 e^{+}\nu_{e})=0.988\pm0.033.Comment: 9 pages; 8 figure

    Common variants at theCHEK2gene locus and risk of epithelial ovarian cancer

    Get PDF
    Genome-wide association studies have identified 20 genomic regions associated with risk of epithelial ovarian cancer (EOC), but many additional risk variants may exist. Here, we evaluated associations between common genetic variants [single nucleotide polymorphisms (SNPs) and indels] in DNA repair genes and EOC risk. We genotyped 2896 common variants at 143 gene loci in DNA samples from 15 397 patients with invasive EOC and controls. We found evidence of associations with EOC risk for variants at FANCA, EXO1, E2F4, E2F2, CREB5 and CHEK2 genes (P ≤ 0.001). The strongest risk association was for CHEK2 SNP rs17507066 with serous EOC (P = 4.74 x 10(-7)). Additional genotyping and imputation of genotypes from the 1000 genomes project identified a slightly more significant association for CHEK2 SNP rs6005807 (r (2) with rs17507066 = 0.84, odds ratio (OR) 1.17, 95% CI 1.11-1.24, P = 1.1×10(-7)). We identified 293 variants in the region with likelihood ratios of less than 1:100 for representing the causal variant. Functional annotation identified 25 candidate SNPs that alter transcription factor binding sites within regulatory elements active in EOC precursor tissues. In The Cancer Genome Atlas dataset, CHEK2 gene expression was significantly higher in primary EOCs compared to normal fallopian tube tissues (P = 3.72×10(-8)). We also identified an association between genotypes of the candidate causal SNP rs12166475 (r (2) = 0.99 with rs6005807) and CHEK2 expression (P = 2.70×10(-8)). These data suggest that common variants at 22q12.1 are associated with risk of serous EOC and CHEK2 as a plausible target susceptibility gene.Other Research Uni

    Evidence that breast cancer risk at the 2q35 locus is mediated through IGFBP5 regulation.

    Get PDF
    GWAS have identified a breast cancer susceptibility locus on 2q35. Here we report the fine mapping of this locus using data from 101,943 subjects from 50 case-control studies. We genotype 276 SNPs using the 'iCOGS' genotyping array and impute genotypes for a further 1,284 using 1000 Genomes Project data. All but two, strongly correlated SNPs (rs4442975 G/T and rs6721996 G/A) are excluded as candidate causal variants at odds against >100:1. The best functional candidate, rs4442975, is associated with oestrogen receptor positive (ER+) disease with an odds ratio (OR) in Europeans of 0.85 (95% confidence interval=0.84-0.87; P=1.7 × 10(-43)) per t-allele. This SNP flanks a transcriptional enhancer that physically interacts with the promoter of IGFBP5 (encoding insulin-like growth factor-binding protein 5) and displays allele-specific gene expression, FOXA1 binding and chromatin looping. Evidence suggests that the g-allele confers increased breast cancer susceptibility through relative downregulation of IGFBP5, a gene with known roles in breast cell biology
    corecore