1,720,971 research outputs found
The most massive galaxies with large depleted cores: structural parameter relations and black hole masses
No full text23 páginasLuminous spheroids (M_(v) ≲ −21.50 ± 0.75 mag) contain partially depleted cores with sizes (R_(b)) typically 0.02–0.5 kpc. However, galaxies with R_(b) > 0.5 kpc are rare and poorly understood. Here, we perform detailed decompositions of the composite surface brightness profiles, extracted from archival Hubble Space Telescope and ground-based images, of 12 extremely luminous "large-core" galaxies that have R_(b) > 0.5 kpc and M_(v) ≲ −23.50 ± 0.10 mag, fitting a core-Sérsic model to the galaxy spheroids. Using 28 "normal-core" (i.e., R_(b) 0.5 kpc) galaxy from the literature, we constructed a final sample of 41 core-Sérsic galaxies. We find that large-core spheroids (with stellar masses M_(*) ≳ 10^(12)M☉) are not simple high-mass extensions of the less luminous normal-core spheroids having M_(*) ∼ 8 × 10^(10)–10^(12)M☉. While the two types follow the same strong relations between the spheroid luminosity L_(v) and R_(b) (R_(b)∝ L_(v)^(1.38±0.13), and the spheroid half-light radius R_(e) (R_(e) ∝ L_(v)^(1.8±0.13), for ellipticals plus Brightest Cluster Galaxies), we discover a break in the core-Sérsic σ–L_(v) relation occurring at M_(v) ∼ −23.50 ± 0.10 mag. Furthermore, we find a strong log-linear R_(b)–M_(BH) relation for the 11 galaxies in the sample with directly determined supermassive black hole (SMBH) masses M_(BH)—3/11 galaxies are large-core galaxies—such that R_(b)∝ M_(BH)^( 0.83 ± 0.10) . However, for the large-core galaxies the SMBH masses estimated from the M_(BH)–σ and core-Sérsic M_(BH)–L relations are undermassive, by up to a factor of 40, relative to expectations from their large Rb values, confirming earlier results. Our findings suggest that large-core galaxies harbor overmassive SMBHs (M_(BH) ≳ 10^(10) M☉), considerably (∼3.7–15.6σ and ∼0.6–1.7σ) larger than expectations from the spheroid σ and L, respectively. We suggest that the R_(b) –M_(BH) relation can be used to estimate SMBH masses in the most massive galaxies.Comunidad de MadridMinisterio de Ciencia, Innovación y Universidades (España)Depto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasInstituto de Física de Partículas y del Cosmos (IPARCOS)TRUEpu
LeMMINGs III. The e-MERLIN legacy survey of the Palomar sample: exploring the origin of nuclear radio emission in active and inactive galaxies through the [O III] - radio connection
Get PDF© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. Artículo firmado por 34 autores. We thank the referee for his or her comments, which helped to improve the paper. This research was supported by a Newton Fund project, DARA (Development in Africa with Radio Astronomy), and awarded by the UK's Science and Technology Facilities Council (STFC) - grant reference ST/R001103/1. This research was supported by European Commission Horizon 2020 Research and Innovation Programme under grant agreement No. 730884 (JUMPING JIVE). FS acknowledges support from a Leverhulme Trust Research Fellowship. JHK acknowledges support from the European Union'sHorizon 2020 research and innovation programme under Marie Sklodowska-Curie grant agreement no. 721463 to the SUNDIAL ITN network, from the State Research Agency (AEI) of the Spanish Ministry of Science and Innovation and the European Regional Development Fund (FEDER) under the grant with reference PID2019-105602GB-I00, and from IAC project P/300724, financed by the Ministry of Science and Innovation, through the State Budget and by the Canary Islands Department of Economy, Knowledge and Employment, through the Regional Budget of the Autonomous Community. IMV thanks the Generalitat Valenciana (funding from the GenT Project CIDEGENT/2018/021) and the MICINN (funding from the Research Project PID2019-108995GBC22). AA and MAPT acknowledge support from the SpanishMCIU through grant PGC2018-098915-B-C21 and from the State Agency for Research of the SpanishMCIU through the `Center of Excellence Severo Ochoa' award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). BTD acknowledges financial support from grant `Ayudas para la realización de proyectos de I + D para jóvenes doctores 2019' funded by Comunidad de Madrid and Universidad Complutense de Madrid under grant no. PR65/19-22417.What determines the nuclear radio emission in local galaxies? To address this question, we combine optical [O III] line emission, robust black hole (BH) mass estimates, and high-resolution e-MERLIN 1 .5-GHz data, from the LeMMINGs survey, of a statistically complete sample of 280 nearby optically active (LINER and Seyfert) and inactive [H II and absorption line galaxies (ALGs)] galaxies. Using [O III] luminosity (L-[o iii]) as a proxy for the accretion power, local galaxies follow distinct sequences in the optical-radio planes of BH activity, which suggest different origins of the nuclear radio emission for the optical classes. The 1 .5-GHz radio luminosity of their parsec-scale cores (L-core) is found to scale with BH mass (M-BH) and [O III] luminosity. Below M-BH similar to 10(6.5 )M(circle dot), stellar processes from non-jetted H II galaxies dominate with (Lcore) proportional to M(BH)(0.61 +/- 0.33 )and L-core proportional to L-[Oiii](0.79 +/- 0.30). Above M-BH similar to 10(6.5 )M(circle dot), accretion-driven processes dominate with L-core proportional to M(BH)(1.5-1.65 )and L-core proportional to L-[Oiii](0.99-1.31) for active galaxies: radio-quiet/loud LINERs, Seyferts, and jetted H II galaxies always display (although low) signatures of radio-emitting BH activity, with L-1.5GHz greater than or similar to 10(19.8) W Hz(-1) and M-BH greater than or similar to 10(7) M-circle dot, on a broad range of Eddington-scaled accretion rates ((m)over dot). Radio-quiet and radio-loud LINERs are powered by low-(m)over dot discs launching sub-relativistic and relativistic jets, respectively. Low-power slow jets and disc/corona winds from moderately high to high-(m)over dot discs account for the compact and edge-brightened jets of Seyferts, respectively. Jetted H II galaxies may host weakly active BHs. Fuel-starved BHs and recurrent activity account for ALG properties. In conclusion, specific accretion-ejection states of active BHs determine the radio production and the optical classification of local active galaxies.Unión Europea. Horizonte 2020Ministerio de Ciencia e Innovación (MICINN)/FEDERCentro de Excelencia Severo OchoaUniversidad Complutense de Madrid/Comunidad de MadridNewton Fund project, DARA (Development in Africa with Radio Astronomy)UK's Science and Technology Facilities Council (STFC) UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC)Leverhulme Trust Research FellowshipIAC project - Ministry of Science and Innovation, through the State BudgetCanary Islands Department of Economy, Knowledge and Employment, through the Regional Budget of the Autonomous CommunityGeneralitat Valenciana (GenT Project)Instituto de Astrofísica de AndalucíaDepto. de Física de la Tierra y AstrofísicaFac. de Ciencias FísicasTRUEpu
The nuclear activity and central structure of the elliptical galaxy NGC 5322
Get PDFWe have analysed a new high-resolution e-MERLIN 1.5 GHz radio continuum map together with HST and SDSS imaging of NGC 5322, an elliptical galaxy hosting radio jets, aiming to understand the galaxy’s central structure and its connection to the nuclear activity. We decomposed the composite HST + SDSS surface brightness profile of the galaxy into an inner stellar disc, a spheroid, and an outer stellar halo. Past works showed that this embedded disc counter-rotates rapidly with respect to the spheroid. The HST images reveal an edge-on nuclear dust disc across the centre, aligned along the major-axis of the galaxy and nearly perpendicular to the radio jets. After careful masking of this dust disc, we find a central stellar mass deficit Mdef in the spheroid, scoured by SMBH binaries with final mass MBH such that Mdef/MBH ∼ 1.3–3.4. We propose a three-phase formation scenario for NGC 5322, where a few (2–7) ‘dry’ major mergers involving SMBHs built the spheroid with a depleted core. The cannibalism of a gas-rich satellite subsequently creates the faint counter-rotating disc and funnels gaseous material directly on to the AGN, powering the radio core with a brightness temperature of TB, core ∼ 4.5 × 107 K and the low-power radio jets (Pjets ∼ 7.04 × 1020 W Hz−1), which extend ∼1.6 kpc. The outer halo can later grow via minor mergers and the accretion of tidal debris. The low-luminosity AGN/jet-driven feedback may have quenched the late-time nuclear star formation promptly, which could otherwise have replenished the depleted core
Bar-driven AGN fuelling in SO galaxies with complex central structures
No full text<p>Nuclear stellar bars, rings and/or spirals in disk galaxies are thought to stimulate the inward funnelling of disk materials, fuelling the AGN. However, how such small-scale structures and the central AGN activities are actually related still remains uncertain. Therefore, we performed a detailed analysis of the structures and isophotal properties for three barred S0 galaxies NGC 2681, NGC 3945 and NGC 4371 having small-scale stellar bars, rings and a point source. Building on this and using our imaging of the narrow lines (Hβ, [O III], Hα, [N II], and [S II]) to measure the pertaining emission fluxes, we constructed the standard BPT diagnostic diagrams. Our results favor bar-related AGN fuelling and nuclear gas ionisation. However, we argue that the bar-driven scenario alone cannot account for the formation of these three S0s.</p
LeMMINGs - IV. The X-ray properties of a statistically complete sample of the nuclei in active and inactive galaxies from the Palomar sample
Get PDFArtículo firmado por 25 autores. We would like to acknowledge the support of the LeMMINGs project, upon which this study is based. We acknowledge funding from the Mayflower Scholarship from the University of Southampton afforded to David Williams to complete this work. This work was also supported by the Oxford Centre for Astrophysical Surveys, which is funded through generous support from the Hintze Family Charitable Foundation. MP acknowledges Royal Society-SERB Newton International Fellowship support funded jointly by the Royal Society, UK and the Science and Engineering Board of India (SERB) through Newton-Bhabha Fund. IMcH thanks the Royal Society for the award of a Royal Society Leverhulme Trust Senior Research Fellowship. RDB and IMcH also acknowledge the support of STFC under grant [ST/M001326/1]. SM gratefully acknowledges the support from the Chandra grant GO7-18080X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of the National Aeronautics Space Administration under contract NAS8-03060. AB is grateful to the Royal Society and SERB (Science and Engineering Research Board, India). AB is supported by an INSPIRE Faculty grant (DST/INSPIRE/04/2018/001265) by the Department of Science and Technology, Govt. of India. PGB acknowledges financial support from the STFC and the Czech Science Foundation project No. 19-05599Y. SA gratefully acknowledges support from an ERC Advanced Grant 789410 JHK acknowledges financial support from the European Union's Horizon 2020 research and innovation programme under Marie Skodowska-Curie grant agreement no. 721463 to the SUNDIAL ITN network, from the State Research Agency (AEI-MCINN) of the Spanish Ministry of Science and Innovation under the grant 'The structure and evolution of galaxies and their central regions' with reference PID2019-105602GB-I00/10.13039/501100011033, and from IAC project P/300724, financed by the Ministry of Science and Innovation, through the State Budget and by the Canary Islands Department of Economy, Knowledge, and Employment, through the Regional Budget of the Autonomous Community. BTD acknowledges support from a Spanish postdoctoral fellowship 'Ayudas 1265 para la atracción del talento investigador. Modalidad 2: jóvenes investigadores.' funded by Comunidad de Madrid under grant number 2016-T2/TIC-2039 and support from grant 'Ayudas para la realización de proyectos de I + D para jóvenes doctores 2019.' funded by Comunidad de Madrid and Universidad Complutense de Madrid under grant number PR65/19-22417. AA and MAPT acknowledge support from the Spanish MCIU through grant PGC2018-098915-B-C21. JM acknowledges support from the grant RTI2018-096228-B-C31 (MICIU/FEDER, EU). AA, MAPT, and JM acknowledge financial support from the State Agency for Research of the Spanish MCIU through the 'Center of Excellence Severo Ochoa' award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709). CGM acknowledges support from Mrs Hiroko and Mr Jim Sherwin. FS acknowledges partial support from a Leverhulme Trust Research Fellowship. We also acknowledge Jodrell Bank Centre for Astrophysics, which is funded by the STFC. e-MERLIN and formerly, MERLIN, is a National Facility operated by the University of Manchester at Jodrell Bank Observatory on behalf of STFC. The scientific results reported in this article are based to a significant degree on observations made by the Chandra X-ray Observatory and on data obtained from the Chandra Data Archive.; This research has made use of software provided by the Chandra X-ray Center (CXC) in the application package ciao. DW would also like to thank Sam Connolly, Dimitrios Emmanolopoulos, and Sara Motta for useful discussions.All 280 of the statistically complete Palomar sample of nearby ( 20 degrees have been observed at 1.5 GHz as part of the LeMMINGs e-MERLIN legacy survey. IIere, we present Chandra X-ray observations of the nuclei of 213 of these galaxies, including a statistically complete sub-set of 113 galaxies in the declination range 40 degrees <delta < 65 degrees. We observed galaxies of all optical spectral types, including 'active' galaxies [e.g. low-ionization nuclear emission line regions (LINERs) and Seyferts] and 'inactive' galaxies like H II galaxies and absorption line galaxies (ALG). The X-ray flux limit of our survey is 1.65 x 10(-14) erg s(-1) cm(-2) (0.3-10 keV). We detect X-ray emission coincident within 2 arcsec of the nucleus in 150/213 galaxies, including 13/14 Seyferts, 68/77 LINERs, 13/22 ALGs and 56/100 H II galaxies, but cannot completely rule out contamination from non-AGN processes in sources with nuclear luminosities less than or similar to 10(39) erg s(-1). We construct an X-ray Luminosity function (XI,F) and find that the local galaxy XLF, when including all active galactic nucleus (AGN) types, can be represented as a single power law of slope -0.54 +/- 0.06. The Eddington ratio of the Seyferts is usually 2-4 decades higher than that of the LINERs, ALGs, and H II galaxies, which are mostly detected with Eddington ratios less than or similar to 10(-3). Using [O III] line measurements and black hole masses from the literature, we show that LINERs, H II galaxies and ALGs follow similar correlations to low luminosities, suggesting that some 'inactive' galaxies may harbour AGN.Unión Europea. Horizonte 2020Ministerio de Ciencia e Innovación (MICINN)/FEDERCentro de Excelencia Severo OchoaComunidad de MadridOxford Centre for Astrophysical Surveys from the Hintze Family Charitable FoundationRoyal Society, UK Royal Society of LondonScience and Engineering Board of India (SERB) through Newton-Bhabha FundRoyal Society of London European CommissionSTFCUK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC)Chandra grantNational Aeronautics Space Administration (NASA)Department of Science and Technology, Govt. of India Department of Science & Technology (India)STFC UK Research & Innovation (UKRI) Science & Technology Facilities Council (STFC)Czech Science Foundation Grant Agency of the Czech RepublicSpanish postdoctoral fellowship 'Ayudas 1265 para la atracción del talento investigador. Modalidad 2: jóvenes investigadores' - Comunidad de MadridGrant 'Ayudas para la realización de proyectos de I + D para jóvenes doctores 2019.' - Comunidad de MadridUniversidad Complutense de MadridLeverhulme Trust Research FellowshipSTFC. e-MERLINCanary Islands Department of Economy, Knowledge, and Employment, through the Regional Budget of the Autonomous CommunityDepto. de Estructura de la Materia, Física Térmica y ElectrónicaFac. de Ciencias FísicasTRUEpu
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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