Revisiting the Fanaroff–Riley dichotomy and radio-galaxy morphology with the LOFAR Two-Metre Sky Survey (LoTSS)

Abstract The relative positions of the high and low surface brightness regions of radio-loud active galaxies in the 3CR sample were found by Fanaroff and Riley to be correlated with their luminosity. We revisit this canonical relationship with a sample of 5805 extended radio-loud active galactic nuclei (AGN) from the LOFAR Two-Metre Sky Survey (LoTSS), compiling the most complete data set of radio-galaxy morphological information obtained to date. We demonstrate that, for this sample, radio luminosity does not reliably predict whether a source is edge-brightened (FRII) or centre-brightened (FRI). We highlight a large population of low-luminosity FRIIs, extending three orders of magnitude below the traditional FR break, and demonstrate that their host galaxies are on average systematically fainter than those of high-luminosity FRIIs and of FRIs matched in luminosity. This result supports the jet power/environment paradigm for the FR break: low-power jets may remain undisrupted and form hotspots in lower mass hosts. We also find substantial populations that appear physically distinct from the traditional FR classes, including candidate restarting sources and ‘hybrids’. We identify 459 bent-tailed sources, which we find to have a significantly higher SDSS cluster association fraction (at z < 0.4) than the general radio-galaxy population, similar to the results of previous work. The complexity of the LoTSS faint, extended radio sources not only demonstrates the need for caution in the automated classification and interpretation of extended sources in modern radio surveys, but also reveals the wealth of morphological information such surveys will provide and its value for advancing our physical understanding of radio-loud AGN.

Download Full-text

Diffuse Cluster Radio Sources

Symposium - International Astronomical Union ◽

10.1017/s0074180900081006 ◽

1996 ◽

Vol 175 ◽

pp. 333-338 ◽

Cited By ~ 21

Author(s):

L. Feretti ◽

G. Giovannini

Keyword(s):

Surface Brightness ◽

Radio Galaxy ◽

Radio Sources ◽

Clusters Of Galaxies ◽

Rare Phenomenon ◽

Low Surface Brightness ◽

Extended Sources ◽

Formation And Evolution

Diffuse radio sources in clusters remain a poorly understood phenomenon. They are very extended sources (0.4-0.6 Mpc), of low surface brightness and steep spectrum, which cannot be identified with any active radio galaxy. They are a rare phenomenon, as they have been found so far in few clusters of galaxies. This paper reviews the current findings about this kind of sources, and the suggestions about their formation and evolution.

Download Full-text

The IAC stripe82 legacy project

Proceedings of the International Astronomical Union ◽

10.1017/s1743921316009005 ◽

2016 ◽

Vol 11 (S321) ◽

pp. 266-266

Author(s):

Javier Román ◽

Juergen Fliri ◽

Ignacio Trujillo

Keyword(s):

Surface Brightness ◽

Dwarf Galaxies ◽

Sloan Digital Sky Survey ◽

Diffuse Light ◽

Imaging Data ◽

Data Set ◽

Unique Possibility ◽

Sky Survey ◽

Low Surface Brightness

AbstractWe present new deep co-adds of data taken within Stripe 82 of the Sloan Digital Sky Survey (SDSS), especially stacked to reach the faintest surface brightness limits of this data set. Our reduction puts special emphasis on preserving the characteristics of the background (sky + diffuse light) in the input images using a non-aggressive sky subtraction strategy, resulting in an exquisite quality on extremely faint structures. The IAC Stripe 82 co-adds offer a rather unique possibility to study the low surface brightness Universe like stellar haloes and disc truncations, low surface brightness, tidal galactic interactions, extremely faint dwarf galaxies, intra-cluster light or diffuse light from galactic dust. The imaging data is publicly available at http://www.iac.es/proyecto/stripe82/.

Download Full-text

A radio spectral index map and catalogue at 147–1400 MHz covering 80 per cent of the sky

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx3125 ◽

2017 ◽

Vol 474 (4) ◽

pp. 5008-5022 ◽

Cited By ~ 28

Author(s):

F de Gasperin ◽

H T Intema ◽

D A Frail

Keyword(s):

Galaxy Evolution ◽

Spectral Index ◽

Radio Galaxy ◽

Galactic Plane ◽

Cosmic Radio ◽

Large Area ◽

Sky Survey ◽

Combining Data ◽

Extended Sources ◽

Lower Limits

Abstract The radio spectral index is a powerful probe for classifying cosmic radio sources and understanding the origin of the radio emission. Combining data at 147 MHz and 1.4 GHz from the TIFR GMRT Sky Survey (TGSS) and the NRAO VLA Sky Survey (NVSS), we produced a large-area radio spectral index map of ∼80 per cent of the sky (Dec. > − 40 deg), as well as a radio spectral index catalogue containing 1396 515 sources, of which 503 647 are not upper or lower limits. Almost every TGSS source has a detected counterpart, while this is true only for 36 per cent of NVSS sources. We released both the map and the catalogue to the astronomical community. The catalogue is analysed to discover systematic behaviours in the cosmic radio population. We find a differential spectral behaviour between faint and bright sources as well as between compact and extended sources. These trends are explained in terms of radio galaxy evolution. We also confirm earlier reports of an excess of steep-spectrum sources along the galactic plane. This corresponds to 86 compact and steep-spectrum source in excess compared to expectations. The properties of this excess are consistent with normal non-recycled pulsars, which may have been missed by pulsation searches due to larger than average scattering along the line of sight.

Download Full-text

Discovery of 178 Giant Radio Galaxies in 1059 deg2 of the Rapid ASKAP Continuum Survey at 888 MHz

Galaxies ◽

10.3390/galaxies9040099 ◽

2021 ◽

Vol 9 (4) ◽

pp. 99

Author(s):

Heinz Andernach ◽

Eric F. Jiménez-Andrade ◽

Anthony G. Willis

Keyword(s):

Radio Galaxy ◽

Angular Size ◽

Radio Galaxies ◽

Infrared Images ◽

Host Galaxies ◽

Photometric Redshifts ◽

Dark Energy Survey ◽

Optical Images ◽

Extended Radio ◽

Energy Survey

We report the results of a visual inspection of images of the Rapid ASKAP Continuum Survey (RACS) in search of extended radio galaxies (ERG) that reach or exceed linear sizes on the order of one Megaparsec. We searched a contiguous area of 1059 deg2 from RAJ = 20h20m to 06h20m, and −50∘<DecJ<−40∘, which is covered by deep multi-band optical images of the Dark Energy Survey (DES) and in which previously only three ERGs larger than 1 Mpc had been reported. For over 1800 radio galaxy candidates inspected, our search in optical and infrared images resulted in hosts for 1440 ERG, for which spectroscopic and photometric redshifts from various references were used to convert their largest angular size (LAS) to projected linear size (LLS). This resulted in 178 newly discovered giant radio sources (GRS) with LLS >1 Mpc, of which 18 exceed 2 Mpc and the largest one is 3.4 Mpc. Their redshifts range from 0.02 to ∼2.0, but only 10 of the 178 new GRS have spectroscopic redshifts. For the 146 host galaxies, the median r-band magnitude and redshift are 20.9 and 0.64, while for the 32 quasars or candidates these are 19.7 and 0.75. Merging the six most recent large compilations of GRS results in 458 GRS larger than 1 Mpc, so we were able to increase this number by ∼39% to 636.

Download Full-text

The eMERLIN and EVN View of FR 0 Radio Galaxies

Galaxies ◽

10.3390/galaxies9040106 ◽

2021 ◽

Vol 9 (4) ◽

pp. 106

Author(s):

Ranieri D. Baldi ◽

Gabriele Giovannini ◽

Alessandro Capetti

Keyword(s):

Radio Galaxy ◽

Lorentz Factor ◽

Radio Galaxies ◽

Relativistic Jets ◽

Radio Structure ◽

Extended Radio ◽

Twin Jets ◽

Core Components ◽

Galaxy Population ◽

5 Ghz

We present the results from high-resolution observations carried out with the eMERLIN UK-array and the European VLBI network (EVN) for a sample of 15 FR 0s, i.e., compact core-dominated radio sources associated with nearby early-type galaxies (ETGs), which represent the bulk of the local radio galaxy population. The 5 GHz eMERLIN observations available for five objects exhibit sub-mJy core components and reveal pc-scale twin jets for four out of five FR 0s once the eMERLIN and JVLA archival visibilities data are combined. The 1.66 GHz EVN observations available for 10 FR 0s display one- and two-sided jetted morphologies and compact cores. The pc-scale core emission contributes, on average, to about one tenth of the total extended radio emission, although we noted an increasing core contribution for flat-/inverted-spectrum sources. We found an unprecedented linear correlation between the pc-scale core luminosity (∼1021.3–1023.6 W Hz−1) and [O III] line luminosity, generally considered as proxy of the accretion power, for a large sample of LINER-type radio-loud low-luminosity active nuclei, all hosted in massive ETGs, which include FR 0s and FR Is. This result represents further evidence of a common jet–disc coupling in FR 0s and FR Is, despite then differing in kpc-scale radio structure. For our objects and for other FR 0 samples reported in the literature, we estimated the jet brightness sidedness ratios, which typically range between one and three. This parameter roughly gauges the jet bulk Lorentz factor Γ, which turns out to range from 1 to 2.5 for most of the sample. This corroborates the scenario that FR 0s are characterized by mildly relativistic jets, possibly as a result of lower-spinning black holes (BHs) than the highly spinning BHs of relativistic-jetted radio galaxies, FR Is.

Download Full-text

SuperWASP variable stars: classifying light curves using citizen science

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab140 ◽

2021 ◽

Vol 502 (1) ◽

pp. 1299-1311

Author(s):

Heidi B Thiemann ◽

Andrew J Norton ◽

Hugh J Dickinson ◽

Adam McMaster ◽

Ulrich C Kolb

Keyword(s):

Variable Stars ◽

Eclipsing Binaries ◽

Light Curves ◽

Data Set ◽

Resultant Data ◽

Sky Survey ◽

Short Period ◽

Contact Binaries ◽

Analysis Of Results

ABSTRACT We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 million classifications corresponding to >500 000 object–period combinations, provided by citizen–scientist volunteers. Volunteer-classified light curves have ∼89 per cent accuracy for detached and semidetached eclipsing binaries, but only ∼9 per cent accuracy for rotationally modulated variables, based on known objects. We demonstrate that this Zooniverse project will be valuable for both population studies of individual variable types and the identification of stellar variables for follow-up. We present preliminary findings on various unique and extreme variables in this analysis, including long-period contact binaries and binaries near the short-period cut-off, and we identify 301 previously unknown binaries and pulsators. We are now in the process of developing a web portal to enable other researchers to access the outputs of the SuperWASP variable stars project.

Download Full-text

Incidence and treatment of feline renal lymphoma: 27 cases

Journal of Feline Medicine and Surgery ◽

10.1177/1098612x20984363 ◽

2021 ◽

pp. 1098612X2098436

Author(s):

Ashlyn G Williams ◽

Ann E Hohenhaus ◽

Kenneth E Lamb

Keyword(s):

Median Survival ◽

Clinical Stage ◽

Large Population ◽

Clinical Signs ◽

Treatment Protocol ◽

Central Nervous System Involvement ◽

Data Set ◽

Hematopoietic Malignancy ◽

Renal Lymphoma ◽

Multicentric Lymphoma

Objectives Lymphoma is the most common feline hematopoietic malignancy. Incidence of renal lymphoma has not been reported as a subset of a large population of feline lymphoma cases. Previous studies have reported renal lymphoma as both a singular entity as well as a component of multicentric disease. The clinical presentation, diagnostic evaluation, therapy and outcomes related to renal lymphoma have not been reported since Mooney et al in 1987. This retrospective study aimed to describe the incidence of renal lymphoma, clinical signs, treatment and survival. Methods Using a database of cats diagnosed with lymphoma between January 2008 and October 2017, cats with renal lymphoma were selected for further analysis. Cases were retrospectively staged according to Mooney et al (1987) and Gabor et al (1998). Data collected included age, clinical signs, clinicopathologic data, diagnostic imaging findings, lymphoma diagnostic method(s), treatment protocol(s) and survival time. Analyses comparing median survival based on therapy administered, renal lymphoma vs multicentric lymphoma, central nervous system involvement, presence of azotemia, anemia and International Renal Interest Society (IRIS) stage at diagnosis were performed. Results From a population of 740 cats with lymphoma, 27 cats had renal lymphoma (incidence, 3.6%), and 14 of those cats had multicentric lymphoma. Fewer stage IV and V cases were identified in this data set compared with Mooney et al; however, not all cats were completely staged. Median survival (range) for cats receiving corticosteroids alone compared with those receiving an L-CHOP (L-asparaginase, vincristine, cyclophosphamide, doxorubicin, prednisolone)-based protocol was 50 days (20–1027 days) in the corticosteroid group and 203 days (44–2364 days) for the L-CHOP group ( P = 0.753) for cats that died secondary to lymphoma. Conclusions and relevance Neither clinical stage nor other factors were predictive of survival. Prospective studies are required to determine the optimal chemotherapy protocol.

Download Full-text

Visual Analysis of Biomarkers Reveals Differences in Lipid Profiles and Liver Enzymes before and after Gastric Sleeve and Bypass

Obesity Facts ◽

10.1159/000510401 ◽

2021 ◽

pp. 1-11

Author(s):

Marijn Marthe Georgine van Berckel ◽

Saskia L.M. van Loon ◽

Arjen-Kars Boer ◽

Volkher Scharnhorst ◽

Simon W. Nienhuijs

Keyword(s):

Bariatric Surgery ◽

Visual Analytics ◽

Biochemical Markers ◽

Visual Analysis ◽

Large Population ◽

High Volume ◽

Cholesterol Concentration ◽

Health State ◽

Data Set ◽

Before And After

Introduction: Bariatric surgery results in both intentional and unintentional metabolic changes. In a high-volume bariatric center, extensive laboratory panels are used to monitor these changes pre- and postoperatively. Consecutive measurements of relevant biochemical markers allow exploration of the health state of bariatric patients and comparison of different patient groups. Objective: The objective of this study is to compare biomarker distributions over time between 2 common bariatric procedures, i.e., sleeve gastrectomy (SG) and gastric bypass (RYGB), using visual analytics. Methods: Both pre- and postsurgical (6, 12, and 24 months) data of all patients who underwent primary bariatric surgery were collected retrospectively. The distribution and evolution of different biochemical markers were compared before and after surgery using asymmetric beanplots in order to evaluate the effect of primary SG and RYGB. A beanplot is an alternative to the boxplot that allows an easy and thorough visual comparison of univariate data. Results: In total, 1,237 patients (659 SG and 578 RYGB) were included. The sleeve and bypass groups were comparable in terms of age and the prevalence of comorbidities. The mean presurgical BMI and the percentage of males were higher in the sleeve group. The effect of surgery on lowering of glycated hemoglobin was similar for both surgery types. After RYGB surgery, the decrease in the cholesterol concentration was larger than after SG. The enzymatic activity of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphate in sleeve patients was higher presurgically but lower postsurgically compared to bypass values. Conclusions: Beanplots allow intuitive visualization of population distributions. Analysis of this large population-based data set using beanplots suggests comparable efficacies of both types of surgery in reducing diabetes. RYGB surgery reduced dyslipidemia more effectively than SG. The trend toward a larger decrease in liver enzyme activities following SG is a subject for further investigation.

Download Full-text

Clustering and Halo Occupation Distribution of Active Galactic Nuclei

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314003937 ◽

2013 ◽

Vol 9 (S304) ◽

pp. 243-243

Author(s):

Takamitsu Miyaji ◽

M. Krumpe ◽

A. Coil ◽

H. Aceves ◽

B. Husemann

Keyword(s):

Cross Correlation ◽

Dynamic Range ◽

Signal To Noise Ratio ◽

Sloan Digital Sky Survey ◽

Dark Matter Halo ◽

Bias Parameter ◽

X Ray ◽

Sky Survey ◽

Galaxy Population ◽

Halo Occupation Distribution

AbstractWe present the results of our series of studies on correlation function and halo occupation distribution of AGNs utilizing data the ROSAT All-Sky Survey (RASS) and the Sloan Digital Sky Survey (SDSS) in the redshift range of 0.07<z<0.36. In order to improve the signal-to-noise ratio, we take cross-correlation approach, where cross-correlation functions (CCF) between AGNs and much more numerous AGNs are analyzed. The calculated CCFs are analyzed using the Halo Occupation Distribution (HOD) model, where the CCFs are divided into the term contributed by the AGN-galaxy pairs that reside in one dark matter halo (DMH), (the 1-halo term) and those from two different DMHs (the 2-halo term). The 2-halo term is the indicator of the bias parameter, which is a function of the typical mass of the DMHs in which AGNs reside. The combination of the 1-halo and 2-halo terms gives, not only the typical DMH mass, but also how the AGNs are distributed among the DMHs as a function of mass separately for those at the center of the DMHs and satellites. The main results are as follows: (1) the range of typical mass of the DMHs in various sub-samples of AGNs log (MDMH/h−1MΘ) ~ 12.4–13.4, (2) we found a dependence of the AGN bias parameter on the X-ray luminosity of AGNs, while the optical luminosity dependence is not significant probably due to smaller dynamic range in luminosity for the optically-selected sample, and (3) the growth of the number of AGNs per DMH (N (MDMH)) with MDMH is shallow, or even may be flat, contrary to that of the galaxy population in general, which grows with MDMH proportionally, suggesting a suppression of AGN triggering in denser environment. In order to investigate the origin of the X-ray luminosity dependence, we are also investigating the dependence of clustering on the black hole mass and the Eddington ratio, we also present the results of this investigation.

Download Full-text

The Structure of the Stellar Hosts in Blue Compact Dwarf Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s174392130600665x ◽

2006 ◽

Vol 2 (S235) ◽

pp. 300-300

Author(s):

R.O. Amorín ◽

J.A.L. Aguerri ◽

L.M. Cairós ◽

N. Caon ◽

C. Muñoz-Tuñón

Keyword(s):

Galaxy Formation ◽

Dwarf Galaxies ◽

Dwarf Galaxy ◽

Structural Parameters ◽

Host Galaxy ◽

Host Galaxies ◽

Galaxy Formation And Evolution ◽

Radial Profiles ◽

Low Surface Brightness ◽

Formation And Evolution

AbstractBlue compact dwarf (BCD) galaxies are gas-rich, low-luminosity (Mb≳-18 mag) and compact systems, currently undergoing violent star-formation burst (Sargent & Searle 1970). While it was initially hypothesized that they were very young galaxies (e.g. Sargent & Searle 1970, et al. 1988), the subsecuent detection of an extended, redder stellar host galaxy showed that the vast majority of them are old systems (e.g. Gil de Paz et al. 2003,2005). BCDs play an important role for understanding the process of galaxy formation and evolution.The structural properties of the low surface brightness stellar host in BCDs are often studied by fitting r1/n models to the outer regions of their radial profiles. The limitations imposed by the presence of a large starburst emission overlapping the underlying component makes this kind of analysis a difficult task.We propose a two-dimensional fitting methodology in order to improve the extraction of the structural parameters of the LSB host Amorín et al. 2006, submitted). A set of ideal simulations are presented in order to test the reliability of the method and to determine its robustness and flexibility. We present the different steps of the method discussing its advantages and weaknesses. We compare the results for a sample of eight objects with those already obtained using a one-dimensional technique (Caon et al. 2005).We fit a PSF convolved Sérsic model to the BVR images with the GALFIT publicly software (Peng et al. 2002). We restrict the fit to the stellar host by masking out the starburst region and take special care to minimize the sky-subtraction uncertainties. Consistency checks are performed to assess the reliability and accuracy of the derived structural parameters.We obtain robust fits for all the sample galaxies, all of which, except one, show low Sérsic indices n—very close to 1—with good agreement in the three bands. These findings suggest that the stellar hosts in BCDs have near-exponential profiles. Since the Sérsic index n of host galaxies is important in the context of the possible structural and evolutionary connections among the different types of dwarf galaxies, we are currently extending the study to a larger sample of objects. This kind of studies will help us to understand the mechanisms that form and shape BCD galaxies, and how they relate to the other dwarf galaxy classes.

Download Full-text