Strategy to Explore Magnetized Cosmic Web with Forthcoming Large Surveys of Rotation Measure

Akahori, Takuya

doi:10.3390/galaxies6040118

Cited by 2 publications

(4 citation statements)

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“…We find a net value of ≈ 10 rad m −2 for the ∆RM 2 signal for random pairs, or an rms contribution of ≈ 7 rad m −2 for each component. This is consistent with the asymptotic value of 5-10 rad m −2 summarized by Akahori (2018) (figure 1 of Akahori) when clusters are excluded from the line of sight, and corresponds to magnetic fields ranging from 0.01 nG to 100 nG, going from voids into filamentary structures. When clusters are included, σ RM is predicted to be 4-8 times larger, which is not consistent with our data.…”

Section: The Igm Contributionsupporting

confidence: 87%

“…These unknowns make it difficult to calculate an accurate and realistic limit. However, these effects are all embodied in cosmological MHD simulations, and so we compare our results to those, such as summarized recently by Akahori (2018). We find a net value of ≈ 10 rad m −2 for the ∆RM 2 signal for random pairs, or an rms contribution of ≈ 7 rad m −2 for each component.…”

Section: The Igm Contributionsupporting

confidence: 65%

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Differences in Faraday Rotation between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields

Vernstrom

Gaensler

Rudnick

et al. 2019

ApJ

112

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Faraday rotation measures (RMs) of extragalactic radio sources provide information on line-of-sight magnetic fields, including contributions from our Galaxy, source environments, and the intergalactic medium (IGM). Looking at differences in RMs, ∆RM, between adjacent sources on the sky can help isolate these different components. In this work, we classify adjacent polarized sources in the NVSS as random or physical pairs. We recompute and correct the uncertainties in the NVSS RM catalog, since these were significantly overestimated. Our sample contains 317 physical and 5111 random pairs, all with Galactic latitudes |b| ≥ 20 • , polarization fractions ≥ 2%, and angular separations between 1.5 and 20 . We find an rms ∆RM of 14.9 ± 0.4 rad m −2 and 4.6 ± 1.1 rad m −2 for random and physical pairs, respectively. This means polarized extragalactic sources that are close on the sky, but at different redshifts, have larger differences in RM than two components of one source. This difference of ∼ 10 rad m −2 is significant at 5σ, and persists in different data subsamples. While there have been other statistical studies of ∆RM between adjacent polarized sources, this is the first unambiguous demonstration that some of this RM difference must be extragalactic, thereby providing a firm upper limit on the RM contribution of the IGM. If the ∆RMs originate local to the sources, then the local magnetic field difference between random sources is a factor of two larger than between components of one source. Alternatively, attributing the difference in ∆RMs to the intervening IGM yields an upper limit on the IGM magnetic field strength of 40 nG.

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Section: The Igm Contributionsupporting

confidence: 87%

Section: The Igm Contributionsupporting

confidence: 65%

Differences in Faraday Rotation between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields

Vernstrom

Gaensler

Rudnick

et al. 2019

ApJ

112

View full text Add to dashboard Cite

show abstract

“…Takuya Akahori studied the optimum frequency range to detect intergalactic magnetic fields with Faraday tomography. He concluded that for fairly small bandwidths around the optimum 500 − 600 MHz, intergalactic Faraday depths of ∼ 5 rad m −2 should become detectable [23,24].…”

Section: Intergalactic Magnetic Fieldsmentioning

confidence: 99%

“…The workshop had 64 participants. The biggest group of these were Japanese (24), there were 19 from Europe (6 Germany,4 Netherlands,4 Italy, 2 UK, 1 France, 1 Spain), 8 from North America (5 Canada, 3 US), 8 from Australia, and 4 from Asia other than Japan (2 South-Korea, 1 Russia, 1 India). A relatively large part of these were young researchers: 28 postdocs, 12 PhD students and 2 MSc students.…”

Section: Introductionmentioning

confidence: 99%