4,470 research outputs found

    The incidence of AGN in galaxies with different stellar population ages

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    It has been argued that recycled gas from stellar mass loss in galaxies might serve as an important fuelling source for black holes (BHs) in their centers. Utilizing spectroscopic samples of galaxies from the Sloan Digital Sky Survey (SDSS) at z=00.35z = 0-0.35 and the Large Early Galaxy Astrophysics Census (LEGA-C) survey at z=0.61z = 0.6-1 that have X-ray coverage from XMM-Newton or Chandra, we test this stellar mass loss fuelling scenario by investigating how AGN activity and BH growth vary with the break strength at 4000 A˚\r{A}, Dn4000\rm D_{n}4000 (which is closely related to the age of stellar populations), as younger galaxies are considered to have higher stellar mass loss rates. We found that when controlling for host-galaxy properties, the fraction of log LXL_{\rm X}/MM_\star > 32 (which roughly corresponds to Eddington ratios 1\gtrsim 1%) AGN and sample-averaged black hole accretion rate (BHAR\rm \overline{BHAR}) decrease with Dn4000\rm D_{n}4000 among Dn4000\rm D_{n}4000 \lesssim 1.9 galaxies, suggesting a higher level of AGN activity among younger galaxies, which supports the stellar mass loss fuelling scenario. For the oldest and most massive galaxies at z=00.35z = 0-0.35, this decreasing trend is not present anymore. We found that, among these most massive galaxies at low redshift, the fraction of low specific-accretion-rate (31 << log LXL_{\rm X}/MM_\star << 32) AGNs increases with Dn4000\rm D_{n}4000, which may be associated with additional fuelling from hot halo gas and/or enhanced accretion capability.Comment: 24 pages, 28 figures. Accepted for publication in MNRA

    The relationship between the incidence of X-ray selected AGN in nearby galaxies & star-formation rate

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    We present the identification and analysis of an X-ray selected AGN sample that lie within the local (z < 0.35) galaxy population. From a parent sample of 22 079 MPA-JHU (based on SDSS DR8) galaxies, we identified 917 galaxies with central, excess X-ray emission (from 3XMM-DR7) likely originating from an AGN. We measured the host galaxies' star formation rates and classified them as either star-forming or quiescent based on their position relative to main sequence of star formation. Only 72 per cent of the X-ray selected sample were identified as AGN using BPT selection; this technique is much less effective in quiescent hosts, only identifying 50 per cent of the X-ray AGN. We also calculated the growth rates of the black holes powering these AGN in terms of their specific accretion rate (∝ LX/M∗) and found quiescent galaxies, on average, accrete at a lower rate than star-forming galaxies. Finally, we measured the sensitivity function of 3XMM so we could correct for observational bias and construct probability distributions as a function of accretion rate. AGN were found in galaxies across the full range of star formation rates () in both star-forming and quiescent galaxies. The incidence of AGN was enhanced by a factor 2 (at a 3.5σ significance) in star-forming galaxies compared to quiescent galaxies of equivalent stellar mass and redshift, but we also found a significant population of AGN hosted by quiescent galaxies

    Hidden Little Monsters: Spectroscopic Identification of Low-mass, Broad-line AGNs at z > 5 with CEERS

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    We report on the discovery of two low-luminosity, broad-line active galactic nuclei (AGNs) at z > 5 identified using JWST NIRSpec spectroscopy from the Cosmic Evolution Early Release Science (CEERS) survey. We detect broad H α emission in the spectra of both sources, with FWHM of 2060 ± 290 km s ^−1 and 1800 ± 200 km s ^−1 , resulting in virial black hole (BH) masses that are 1–2 dex below those of existing samples of luminous quasars at z > 5. The first source, CEERS 2782 at z = 5.242, is 2–3 dex fainter than known quasars at similar redshifts and was previously identified as a candidate low-luminosity AGN based on its morphology and rest-frame optical spectral energy distribution (SED). We measure a BH mass of M _BH = (1.3 ± 0.4) × 10 ^7 M _⊙ , confirming that this AGN is powered by the least massive BH known in the Universe at the end of cosmic reionization. The second source, CEERS 746 at z = 5.624, is inferred to be a heavily obscured, broad-line AGN caught in a transition phase between a dust-obscured starburst and an unobscured quasar. We estimate its BH mass to be in the range of M _BH ≃ (0.9–4.7) × 10 ^7 M _⊙ , depending on the level of dust obscuration assumed. We perform SED fitting to derive host stellar masses, M _⋆ , allowing us to place constraints on the BH–galaxy mass relationship in the lowest mass range yet probed in the early Universe. The M _BH / M _⋆ ratio for CEERS 2782, in particular, is consistent with or higher than the empirical relationship seen in massive galaxies at z = 0. We examine the narrow emission line ratios of both sources and find that their location on the BPT and OHNO diagrams is consistent with model predictions for moderately low metallicity AGNs with Z / Z _⊙ ≃ 0.2–0.4. The spectroscopic identification of low-luminosity, broad-line AGNs at z > 5 with M _BH ≃ 10 ^7 M _⊙ demonstrates the capability of JWST to push BH masses closer to the range predicted for the BH seed population and provides a unique opportunity to study the early stages of BH–galaxy assembly

    Lattices of varieties of plactic-like monoids

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    We study the equational theories and bases of meets and joins of several varieties of plactic-like monoids. Using those results, we construct sublattices of the lattice of varieties of monoids, generated by said varieties. We calculate the axiomatic ranks of their elements, obtain plactic-like congruences whose corresponding factor monoids generate varieties in the lattice, and determine which varieties are joins of the variety of commutative monoids and a finitely generated variety. We also show that the hyposylvester and metasylvester monoids generate the same variety as the sylvester monoid.Comment: 36 pages, 3 figures, 1 tabl

    TRINITY IV: Predictions for Supermassive Black Holes at z7z \gtrsim 7

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    We present predictions for the high-redshift halo-galaxy-supermassive black hole (SMBH) connection from the TRINITY model. Constrained by a comprehensive compilation of galaxy (0z100\leq z \leq 10) and SMBH datasets (0z6.50\leq z \leq 6.5), TRINITY finds: 1) The number of SMBHs with M>109MM_\bullet > 10^9 M_\odot in the observable Universe increases by six orders of magnitude from z10z\sim10 to z2z\sim2, and by another factor of 3\sim 3 from z2z\sim2 to z=0z=0; 2) The M>109/1010MM_\bullet > 10^9/10^{10} M_\odot SMBHs at z6z\sim 6 live in haloes with (23)/(35)×1012M\sim (2-3)/(3-5) \times 10^{12} M_\odot; 3) the new JWST AGNs at 7z117\lesssim z \lesssim 11 are broadly consistent with the median SMBH mass-galaxy mass relation for AGNs from TRINITY; 4) Seeds from runaway mergers in nuclear star clusters are viable progenitors for the SMBHs in GN-z11 (z=10.6z=10.6) and CEERS_1019 (z=8.7z=8.7); 5) z=610z=6-10 quasar luminosity functions from wide area surveys by, e.g., Roman and Euclid, will reduce uncertainties in the z=610z=6-10 SMBH mass-galaxy mass relation by up to 0.5\sim 0.5 dex.Comment: 15 pages, 12 figures, submitted to MNRAS. Questions and comments are welcome

    Global survival trends for brain tumors, by histology: Analysis of individual records for 67,776 children diagnosed in 61 countries during 2000–2014 (CONCORD-3): ntroduction: Tumors of the central nervous system are among the leading causes of cancer-related death in children. Population-based cancer survival reflects the overall effectiveness of a health care system in managing cancer. Inequity in access to care world-wide may result in survival disparities.Methods: We considered children (0-14 years) diagnosed with a brain tumor during 2000-2014, regardless of tumor behavior. Data underwent a rigorous, three-phase quality control as part of CONCORD-3. We implemented a revised version of the International Classification of Childhood Cancer (third edition) to control for under-registration of non-malignant astrocytic tumors. We estimated net survival using the unbiased nonparametric Pohar Perme estimator.Results: The study included 67,776 children. We estimated survival for 12 histology groups, each based on relevant ICD-O-3 codes. Age-standardized 5-year net survival for low-grade astrocytoma ranged between 84% and 100% world-wide during 2000-2014. In most countries, 5-year survival was 90% or more during 2000-2004, 2005-2009, and 2010-2014. Global variation in survival for medulloblastoma was much wider, with age-standardized 5-year net survival between 47% and 86% for children diagnosed during 2010-2014.Conclusions: To the best of our knowledge, this study provides the largest account to date of global trends in population-based survival for brain tumors in children, by histology. We devised an enhanced version of ICCC-3 to account for differences in cancer registration practices world-wide. Our findings may have public health implications, because low-grade glioma is 1 of the 6 index childhood cancers included by WHO in the Global Initiative for Childhood Cancer.

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    Abstract Introduction Tumors of the central nervous system are among the leading causes of cancer-related death in children. Population-based cancer survival reflects the overall effectiveness of a health care system in managing cancer. Inequity in access to care world-wide may result in survival disparities. Methods We considered children (0–14 years) diagnosed with a brain tumor during 2000–2014, regardless of tumor behavior. Data underwent a rigorous, three-phase quality control as part of CONCORD-3. We implemented a revised version of the International Classification of Childhood Cancer (third edition) to control for under-registration of non-malignant astrocytic tumors. We estimated net survival using the unbiased nonparametric Pohar Perme estimator. Results The study included 67,776 children. We estimated survival for 12 histology groups, each based on relevant ICD-O-3 codes. Age-standardized 5-year net survival for low-grade astrocytoma ranged between 84% and 100% world-wide during 2000–2014. In most countries, 5-year survival was 90% or more during 2000–2004, 2005–2009, and 2010–2014. Global variation in survival for medulloblastoma was much wider, with age-standardized 5-year net survival between 47% and 86% for children diagnosed during 2010–2014. Conclusions To the best of our knowledge, this study provides the largest account to date of global trends in population-based survival for brain tumors in children, by histology. We devised an enhanced version of ICCC-3 to account for differences in cancer registration practices world-wide. Our findings may have public health implications, because low-grade glioma is 1 of the 6 index childhood cancers included by WHO in the Global Initiative for Childhood Cancer
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