Trauma

Whittam, Benjamin; Karmazyn, Boaz; Cain, Mark P.

doi:10.1007/978-1-4614-8654-1_20

Cited by 15 publications

(35 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We refer to these sources as 'modelled' sources. Otherwise, we fix the central flux density to the LA value and the spectral index to the median of the spectral index distribution at the appropriate flux density (Whittam et al 2013); we refer to these as 'fixed' sources. We use a covariance matrix to account for the remaining source confusion at < 4𝜎 LA as well as the primordial CMB anisotropies and (uncorrelated) instrumental noise.…”

Section: Ami-sa Analysismentioning

confidence: 99%

A 15.5 GHz detection of the galaxy cluster minihalo in RXJ1720.1+2638

Perrott

Carvalho²,

Elwood

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

RXJ1720.1+2638 is a cool-core, ‘relaxed-appearing’ cluster with a minihalo previously detected up to 8.4 GHz, confined by X-ray-detected cold fronts. We present observations of the minihalo at 13 – 18 GHz with the Arcminute Microkelvin Imager telescope, simultaneously modelling the Sunyaev–Zel’dovich signal of the cluster in conjunction with Planck and Chandra data in order to disentangle the non-thermal emission of the minihalo. We show that the previously-reported steepening of the minihalo emission at 8.4 GHz is not supported by the AMI data and that the spectrum is consistent with a single power-law up to 18 GHz. We also show the presence of a larger-scale component of the minihalo extending beyond the cold fronts. Both of these observations could be explained by the ‘hadronic’ or ‘secondary’ mechanism for the production of relativistic electrons, rather than the currently-favoured ‘re-acceleration’ mechanism and/or multiple episodes of jet activity from the active galactic nucleus in the brightest cluster galaxy.

show abstract

Section: Ami-sa Analysismentioning

confidence: 99%

A 15.5 GHz detection of the galaxy cluster minihalo in RXJ1720.1+2638

Perrott

Carvalho²,

Elwood

et al. 2021

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

show abstract

“…The spectral index cut-off of -0.8 was chosen to ensure that in all flux density bins, any source with spectral index less than this value ought to be detected in NVSS, given its completeness limit of 3.4 mJy. Whittam et al (2013) subsequently studied the radio properties of a sub-sample of 296 10C sources in the Lockman Hole using much deeper surveys at 1.4 GHz and 610 MHz. They found that the median spectral index between 15.7 GHz and 610 MHz changes from -0.75 for S 15.7 > 1.5 mJy to -0.08 for S 15.7 < 0.8 mJy.…”

Section: Previous Workmentioning

confidence: 99%

“…We used data from Whittam et al (2013) to include points between 0.5 and 1.0 mJy when using a spectral index cut-off of -0.5. We used their published measurements of α 15.7 1.4 for 51 of the 296 sources which form a sample complete to 0.5 mJy and are between 0.5 and 1.0 mJy.…”

Section: Combining Data From the At20g 9c And 10c Surveysmentioning

confidence: 99%

“…Bottom: Same as above except that a spectral index cut-off of -0.5 is applied. '10C ⋆ ' designates a region of the 10C survey in the Lockman Hole in which spectral index information from Whittam et al (2013) was used. free-free and spinning dust.…”

Section: Comparison With the 5-ghz Source-count Model By Jackson And Wallmentioning

confidence: 99%

“…In contrast, in the 10C survey, which covers ≈ 27 deg 2 complete to 1.0 mJy and ≈ 12 deg 2 complete to 0.5 mJy, a completely different trend was found in which the fraction of steep-spectrum sources declined with flux density for these fainter sources. A subsample of 10C sources in the Lockman Hole was studied in detail by Whittam et al (2013) at 610 MHz and 1.4 GHz. They think it is likely that the faint, flat-spectrum sources are a result of the cores of FRI sources becoming dominant at 15.7 GHz.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Deep 20-GHz survey of the Chandra Deep Field South and SDSS Stripe 82: source catalogue and spectral properties

Franzen

Sadler

Chhetri

et al. 2014

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present a source catalogue and first results from a deep, blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array, with follow-up observations at 5.5, 9 and 18 GHz. The Australia Telescope 20 GHz (AT20G) deep pilot survey covers a total area of 5 deg 2 in the Chandra Deep Field South and in Stripe 82 of the Sloan Digital Sky Survey. We estimate the survey to be 90% complete above 2.5 mJy. Of the 85 sources detected, 55% have steep spectra (α 20 1.4 < −0.5) and 45% have flat or inverted spectra (α 20 1.4 −0.5). The steep-spectrum sources tend to have single power-law spectra between 1.4 and 18 GHz, while the spectral indices of the flat-or inverted-spectrum sources tend to steepen with frequency. Among the 18 inverted-spectrum (α 20 1.4 0.0) sources, 10 have clearly defined peaks in their spectra with α 5.51.4 > 0.15 and α 18 9 < −0.15. On a 3-yr timescale, at least 10 sources varied by more than 15% at 20 GHz, showing that variability is still common at the low flux densities probed by the AT20G-deep pilot survey.We find a strong and puzzling shift in the typical spectral index of the 15-20-GHz source population when combining data from the AT20G, Ninth Cambridge and Tenth Cambridge surveys: there is a shift towards a steeper-spectrum population when going from ∼ 1 Jy to ∼ 5 mJy, which is followed by a shift back towards a flatter-spectrum population below ∼ 5 mJy. The 5-GHz source-count model by Jackson & Wall (1999), which only includes contributions from FRI and FRII sources, and star-forming galaxies, does not reproduce the observed flattening of the flat-spectrum counts below ∼ 5 mJy. It is therefore possible that another population of sources is contributing to this effect.

show abstract

The Lockman Hole with LOFAR: Searching for GPS and CSS sources at low frequencies

et al. 2016

View full text Add to dashboard Cite

The Lockman Hole Project is a wide international collaboration aimed at exploiting the multi‐band extensive and deep information available for the Lockman Hole region, with the aim of better characterizing the physical and evolutionary properties of the various source populations detected in deep radio fields. Recent observations with the LOw‐Frequency ARray (LOFAR) extends the multi‐frequency radio information currently available for the Lockman Hole (from 350 MHz up to 15 GHz) down to 150 MHz, allowing us to explore a new radio spectral window for the faint radio source population. These LOFAR observations allow us to study the population of sources with spectral peaks at lower radio frequencies, providing insight into the evolution of GPS and CSS sources. In this general framework, I present preliminary results from 150 MHz LOFAR observations of the Lockman Hole field. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

show abstract

Trauma

Cited by 15 publications

References 48 publications

A 15.5 GHz detection of the galaxy cluster minihalo in RXJ1720.1+2638

A 15.5 GHz detection of the galaxy cluster minihalo in RXJ1720.1+2638

Deep 20-GHz survey of the Chandra Deep Field South and SDSS Stripe 82: source catalogue and spectral properties

The Lockman Hole with LOFAR: Searching for GPS and CSS sources at low frequencies

Contact Info

Product

Resources

About