1,725,905 research outputs found
NGC 4993 and other short gamma-ray burst host galaxies
No full textWe present the spectral detailed modelling of NGC 4993 – the host galaxy of GW 170817 – and other short gamma-ray burst (SGRB) host galaxies. In order to determine their physical conditions and the element abundances, we have gathered spectroscopic and photometric data from the literature. The observation data are sometimes missing, preventing us from fully constraining the model. However, for most of the SGRB hosts the [OIII]5007/Hβ and [NII]6548/Hα line ratios are reported. The analysis of NGC 4993 by a composite model (photoionization+shock) confirms that an active galactic nucleus (AGN), most probably a low-ionization nuclear emission-line region (LINER) or a low-luminosity AGN (LLAGN) is the gas photoionization source. Shock velocities and preshock densities are similar to those found in the narrow line region of AGN. O/H and N/H have solar values. For the other SGRB of the sample, we found that O/H ratios are nearly solar, while N/H covers a much larger range of values at redshifts close to 0.4. In NGC 4993, the relative contribution to the spectral energy distribution of an old stellar population, characterized by a black-body temperature of Tbb = 4000 K, with respect to bremsstrahlung is higher by a factor of >100 than in most of the local AGN and starburst (SB) galaxies. For the other SGRB that compose the sample, Tbb ranges between 2000 K for SGRB 100206A and 8000 K for SGRB 111117A
Linked collectors and determiners for: Canadian Museum of Nature Parasite Collection.
No full textNatural history specimen data linked to collectors and determiners held within, "Canadian Museum of Nature Parasite Collection". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/00ed18ea-4993-4809-a656-62363baa4808">https://bionomia.net/dataset/00ed18ea-4993-4809-a656-62363baa4808</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/00ed18ea-4993-4809-a656-62363baa4808">https://gbif.org/dataset/00ed18ea-4993-4809-a656-62363baa4808</a>. Formatted as a Frictionless Data package
Linked collectors and determiners for: Canadian Museum of Nature Parasite Collection.
No full textNatural history specimen data linked to collectors and determiners held within, "Canadian Museum of Nature Parasite Collection". Claims or attributions were made on Bionomia by volunteer Scribes, <a href="http://bionomia.net/dataset/00ed18ea-4993-4809-a656-62363baa4808">https://bionomia.net/dataset/00ed18ea-4993-4809-a656-62363baa4808</a> using specimen data from the dataset aggregated by the Global Biodiversity Information Facility, <a href="https://gbif.org/dataset/00ed18ea-4993-4809-a656-62363baa4808">https://gbif.org/dataset/00ed18ea-4993-4809-a656-62363baa4808</a>. Formatted as a Frictionless Data package
The Distance to NGC 4993: The Host Galaxy of the Gravitational-wave Event GW170817
No full textThe historic detection of gravitational waves from a binary neutron star merger (GW170817) and its electromagnetic counterpart led to the first accurate (sub-arcsecond) localization of a gravitational-wave event. The transient was found to be ∼10″ from the nucleus of the S0 galaxy NGC 4993. We report here the luminosity distance to this galaxy using two independent methods. (1) Based on our MUSE/VLT measurement of the heliocentric redshift (z helio =0.009783 ±0.000023), we infer the systemic recession velocity of the NGC 4993 group of galaxies in the cosmic microwave background (CMB) frame to be v CMB =3231 ±53 km s -1 . Using constrained cosmological simulations we estimate the line-of-sight peculiar velocity to be v pec =307 ±230 km s -1 , resulting in a cosmic velocity of v cosmic =2924 ±236 km s -1 (z cosmic =0.00980 ±0.00079) and a distance of D z =40.4 ±3.4 Mpc assuming a local Hubble constant of H 0 =73.24 ±1.74 km s -1 Mpc -1 . (2) Using Hubble Space Telescope measurements of the effective radius (15.″5 ±1.″5) and contained intensity and MUSE/VLT measurements of the velocity dispersion, we place NGC 4993 on the Fundamental Plane (FP) of E and S0 galaxies. Comparing to a frame of 10 clusters containing 226 galaxies, this yields a distance estimate of D FP =44.0 ±7.5 Mpc. The combined redshift and FP distance is D NGC 4993 =41.0 ±3.1 Mpc. This "electromagnetic" distance estimate is consistent with the independent measurement of the distance to GW170817 as obtained from the gravitational-wave signal ( Mpc) and confirms that GW170817 occurred in NGC 4993
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
The distance to NGC 4993 : the host galaxy of the gravitational-wave event GW170817
Get PDFThe historic detection of gravitational waves from a binary neutron star merger (GW170817) and its electromagnetic counterpart led to the first accurate (sub-arcsecond) localization of a gravitational-wave event. The transient was found to be ∼1000 from the nucleus of the S0 galaxy NGC 4993. We report here the luminosity distance to this galaxy using two independent methods. (1) Based on our MUSE/VLT measurement of the heliocentric redshift (zhelio = 0.009783±0.000023) we infer the systemic recession velocity of the NGC 4993 group of galaxies in the cosmic microwave background (CMB) frame to be vCMB = 3231±53 km s−1 . Using constrained cosmological simulations we estimate the line-of-sight peculiar velocity to be vpec = 307±230 km s−1 , resulting in a cosmic velocity of vcosmic = 2924±236 km s−1 (zcosmic = 0.00980±0.00079) and a distance of Dz = 40.4±3.4 Mpc assuming a local Hubble constant of H0 = 73.24± 1.74 km s−1Mpc−1 . (2) Using Hubble Space Telescope measurements of the effective radius (15. 005±1. 005) and contained intensity and MUSE/VLT measurements of the velocity dispersion, we place NGC 4993 on the Fundamental Plane (FP) of E and S0 galaxies. Comparing to a frame of 10 clusters containing 226 galaxies, this yields a distance estimate of DFP = 44.0±7.5 Mpc. The combined redshift and FP distance is DNGC4993 = 41.0±3.1 Mpc. This ‘electromagnetic’ distance estimate is consistent with the independent measurement of the distance to GW170817 as obtained from the gravitational-wave signal (DGW = 43.8 +2.9 −6.9 Mpc) and confirms that GW170817 occurred in NGC 4993
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