scholarly journals The XXL Survey

2019 ◽  
Vol 633 ◽  
pp. A6 ◽  
Author(s):  
R. A. J. Eyles ◽  
M. Birkinshaw ◽  
V. Smolčić ◽  
C. Horellou ◽  
M. Huynh ◽  
...  
Keyword(s):  
General Population ◽  
Flux Density ◽  
Primary Beam ◽  
Spectral Indices ◽  
Number Density ◽  
X Ray ◽  
Density Limit ◽  
Linear Polarisation ◽  
Compact Array

Aims. We investigate the properties of the polarised radio population in the central 6.5 deg2 of the XXL-South field observed at 2.1 GHz using the Australia Telescope Compact Array (ATCA) in 81 pointings with a synthesised beam of FWHM 5.2″. We also investigate the ATCA’s susceptibility to polarisation leakage. Methods. We performed a survey of a 5.6 deg2 subregion and calculated the number density of polarised sources. We derived the total and polarised spectral indices, in addition to comparing our source positions with those of X-ray-detected clusters. We measured the polarisation of sources in multiple pointings to examine leakage in the ATCA. Results. We find 39 polarised sources, involving 50 polarised source components, above a polarised flux density limit of 0.2 mJy at 1.332 GHz. The number density of polarised source components is comparable with recent surveys, although there is an indication of an excess at ∼1 mJy. We find that those sources coincident with X-ray clusters are consistent in their properties with regard to the general population. In terms of the ATCA leakage response, we find that ATCA mosaics with beam separation of ≲2/3 of the primary beam FWHM have off-axis linear polarisation leakage ≲1.4% at 1.332 GHz.

scholarly journals Simultaneous X-ray and radio observations of the transitional millisecond pulsar candidate CXOU J110926.4–650224

2021 ◽  
Vol 655 ◽  
pp. A52
Author(s):  
F. Coti Zelati ◽  
B. Hugo ◽  
D. F. Torres ◽  
D. de Martino ◽  
A. Papitto ◽  
...  
Keyword(s):  
Radio Emission ◽  
Flux Density ◽  
Millisecond Pulsar ◽  
Radio Emissions ◽  
X Ray ◽  
Link Type ◽  
Upper Limit ◽  
Variability Pattern ◽  
Average Flux ◽  
Compact Array

We present the results of simultaneous observations of the transitional millisecond pulsar (tMSP) candidate CXOU J110926.4–650224 with the XMM-Newton satellite and the MeerKAT telescope. The source was found at an average X-ray luminosity of LX ≃ 7 × 1033 erg s−1 over the 0.3−10 keV band (assuming a distance of 4 kpc) and displayed a peculiar variability pattern in the X-ray emission, switching between high, low and flaring modes on timescales of tens of seconds. A radio counterpart was detected at a significance of 7.9σ with an average flux density of ≃33 μJy at 1.28 GHz. It showed variability over the course of hours and emitted a ≃10-min long flare just a few minutes after a brief sequence of multiple X-ray flares. No clear evidence for a significant correlated or anticorrelated variability pattern was found between the X-ray and radio emissions over timescales of tens of minutes and longer. CXOU J110926.4–650224 was undetected at higher radio frequencies in subsequent observations performed with the Australia Telescope Compact Array, when the source was still in the same X-ray sub-luminous state observed before, down to a flux density upper limit of 15 μJy at 7.25 GHz (at 3σ). We compare the radio emission properties of CXOU J110926.4–650224 with those observed in known and candidate tMSPs and discuss physical scenarios that may account for its persistent and flaring radio emissions.

scholarly journals New Radio Observations of Circinus X-1: A Summary

1998 ◽  
Vol 164 ◽  
pp. 343-344
Author(s):  
R. P. Fender
Keyword(s):  
Flux Density ◽  
Radio Flux ◽  
Radio Observations ◽  
X Ray ◽  
New Radio ◽  
Compact Array

AbstractNew radio observations from the Australia Telescope Compact Array of the radio jet X-ray binary Circinus X-1 are summarized. Radio flux density monitoring around nearly an entire orbit is presented, confirming continued radio flaring around phase 0.1 (near periastron passage) as well as a lesser enhancement half an orbit later.

scholarly journals POS0045 LEAST SIGNIFICANT CHANGE IN BONE DENSITOMETRY IN PATIENTS WITH OBESITY

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 227.2-228
Author(s):  
D. Claire ◽  
M. Geoffroy ◽  
L. Kanagaratnam ◽  
C. Isabelle ◽  
A. Hittinger ◽  
...  
Keyword(s):  
Bone Mineral Density ◽  
Lumbar Spine ◽  
General Population ◽  
Bone Mineral ◽  
Bone Densitometry ◽  
Dual Energy ◽  
Mineral Density ◽  
Least Significant Change ◽  
X Ray ◽  
Significant Change

Background:Dual energy X-ray absoprtiometry is the reference method to mesure bone mineral density (1). Loss of bone mineral density is significant if it exceeds the least significant change. The threshold value used in general population is 0,03 g/cm2 (2). Patients with obesity are known for having a higher bone mineral density due to metabolism and physiopathology characteristics (3,4).Objectives:The aim of our study was to determine the least significant change in bone densitometry in patients with obesity.Methods:We conducted an interventionnal study in 120 patients with obesity who performed a bone densitometry. We measured twice the bone mineral density at the lumbar spine, the femoral neck and the total hip in the same time (5,6). We determined the least significant change in bone densitometry from each pair of measurements, using the Bland and Altman method. We also determined the least significant change in bone densitometry according to each stage of obesity.Results:The least significant change in bone densitometry in patients with obesity is 0,046g/cm2 at the lumbar spine, 0.069 g/cm2 at the femoral neck and 0.06 g/cm2 at the total hip.Conclusion:The least significant change in bone densitometry in patients with obesity is higher than in general population. These results may improve DXA interpretation in this specific population, and may personnalize their medical care.References:[1]Lees B, Stevenson JC. An evaluation of dual-energy X-ray absorptiometry and comparison with dual-photon absorptiometry. Osteoporos Int. mai 1992;2(3):146-52.[2]Briot K, Roux C, Thomas T, Blain H, Buchon D, Chapurlat R, et al. Actualisation 2018 des recommandations françaises du traitement de l’ostéoporose post-ménopausique. Rev Rhum. oct 2018;85(5):428-40.[3]Shapses SA, Pop LC, Wang Y. Obesity is a concern for bone health with aging. Nutr Res N Y N. mars 2017;39:1-13.[4]Savvidis C, Tournis S, Dede AD. Obesity and bone metabolism. Hormones. juin 2018;17(2):205-17.[5]Roux C, Garnero P, Thomas T, Sabatier J-P, Orcel P, Audran M, et al. Recommendations for monitoring antiresorptive therapies in postmenopausal osteoporosis. Jt Bone Spine Rev Rhum. janv 2005;72(1):26-31.[6]Ravaud P, Reny JL, Giraudeau B, Porcher R, Dougados M, Roux C. Individual smallest detectable difference in bone mineral density measurements. J Bone Miner Res. août 1999;14(8):1449-56.Disclosure of Interests:None declared.

scholarly journals A Comparison of the X-ray Spectra of Quasars and BL Lac Objects

1989 ◽  
Vol 134 ◽  
pp. 197-198
Author(s):  
D. M. Worrall ◽  
B. J. Wilkes
Keyword(s):  
Power Law ◽  
Radio Spectrum ◽  
Spectral Indices ◽  
Mean Power ◽  
Bl Lac Objects ◽  
X Ray ◽  
Bl Lac ◽  
Infrared Frequencies

Quasars with similar core-compact radio properties can be classified by their differences at optical and infrared frequencies. Their X-ray properties might be expected to be similar if the synchrotron self-Compton mechanism relates their radio and X-ray emission. We have compared the 0.2–3.5 keV mean power-law energy spectral indices, , for 4 quasar classes: 12 Highly Polarized QSOs (HPQs), 19 Flat Radio Spectrum, core-compact, low-polarization, QSOs (FRS QSOs), 24 radio-selected BL Lac objects, and 7 X-ray-selected BL Lac objects.

scholarly journals Radio Outbursts from Cygnus X-3

1974 ◽  
Vol 60 ◽  
pp. 401-405 ◽  
Author(s):  
V. A. Hughes ◽  
M. R. Viner ◽  
A. Woodsworth
Keyword(s):  
Flux Density ◽  
Periodic Modulation ◽  
X Ray ◽  
Infrared Wavelengths

The variation in flux density obtained at 10522 MHz for Bursts 2, 3, and 4 is compared with that obtained by others at frequencies down to 365 MHz. The bursts appear to have a quasi-periodic modulation with a period of 3–4 h, which is different from the 4.8-h periodicity observed at X-ray and infrared wavelengths. The modulation is attributed to a fluctuation in the size of the expanding cloud of particles produced by either an instability in the atmosphere of Cygnus X-3 or by a built-in instability in the cloud itself.

scholarly journals The Evolution and Distance to SCORPIUS X-1

1998 ◽  
Vol 164 ◽  
pp. 339-340
Author(s):  
E. B. Fomalont ◽  
C. F. Bradshaw ◽  
B. J. Geldzahler
Keyword(s):  
Flux Density ◽  
X Ray ◽  
The Third ◽  
Trigonometric Parallax ◽  
Relative Luminosity ◽  
5 Ghz ◽  
Eddington Limit

AbstractFrom three VLBA observations at 5 GHz, spanning 13 months, we have measured the trigonometric parallax of Sco X-1 of 0.23 ± 0.28 mas; hence its distance is > 1300 pc. This supports the hypothesis that the the x-ray luminosity is near the Eddington Limit.All three VLBA observations show a radio core of flux density 0.5 mJy and size < 4 mas. However, the third VLBA observation revealed two additional radio components, separated by 12 mas (≈ 20 au) on opposite sides of the radio core. The evolution of these new components is unknown until additional observations can be made. The relative luminosity and separation of the two radio components are inconsistent with the Doppler beaming of two identical ejecta from the radio core.

scholarly journals Anomalous Grazing X-ray Reflectometry for Determining the Number Density of Atoms in the Near-Surface Region

1996 ◽  
Vol 37 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Masatoshi Saito ◽  
Eiichiro Matsubara ◽  
Yoshio Waseda
Keyword(s):  
Surface Region ◽  
Number Density ◽  
Near Surface ◽  
X Ray

scholarly journals Clinical signs of early osteoarthritis: reproducibility and relation to x ray changes in 541 women in the general population.

1991 ◽  
Vol 50 (7) ◽  
pp. 467-470 ◽  
Author(s):  
D J Hart ◽  
T D Spector ◽  
P Brown ◽  
P Wilson ◽  
D V Doyle ◽  
...  
Keyword(s):  
General Population ◽  
Clinical Signs ◽  
Early Osteoarthritis ◽  
X Ray

scholarly journals Radio continuum observations of massive stars in open cluster NGC 6231 and the Sco OB1 association

2003 ◽  
Vol 212 ◽  
pp. 230-231 ◽  
Author(s):  
Diah Y.A. Setia Gunawan ◽  
Jessica M. Chapman ◽  
Ian R. Stevens ◽  
Gregor Rauw ◽  
Claus Leitherer
Keyword(s):  
Massive Stars ◽  
Open Cluster ◽  
Radio Continuum ◽  
Spectral Indices ◽  
Program Show ◽  
Compact Array

We present results of the Australia Telescope Compact Array (ATCA) radio continuum observations of massive stars in the Sco OB1 association. Most stars detected in the program show spectral indices lower than value expected from thermal free-free emission.

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