The first IRAM/PdBI polarimetric millimeter survey of active galactic nuclei

Trippe, Sascha; Neri, R.; Krips, M.; Castro-Carrizo, A.; Bremer, M.; Piétu, V.; Winters, J. M.

doi:10.1051/0004-6361/201118563

Cited by 16 publications

(19 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even though the values we derive for RM and B || are fairly high, they are by no means extraordinary. Values of |RM| ≈ 5 × 10 5 rad m −2 can be seen also in the radio nucleus of the Seyfert 1 galaxy 1637+574 (Trippe et al ) and, most notably, in the Galactic Centre radio source Sagittarius A* (Macquart et al ; Marrone et al ). Magnetic fields with

B_{| |} \approx 100 μ

G are compatible to those found in the centre of the Milky Way, where field strengths in the range of ≈100 μG–1 mG have been reported (e.g.…”

Section: Discussionmentioning

confidence: 91%

A search for linear polarization in the active galactic nucleus 3C 84 at 239 and 348 GHz

Trippe

Bremer

Krichbaum

et al. 2012

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

We report a search for linear polarization in the active galactic nucleus (AGN) 3C 84 (NGC 1275) at observed frequencies of 239 and 348 GHz, corresponding to rest‐frame frequencies of 243 and 354 GHz. We collected polarization data with the IRAM Plateau de Bure Interferometer via Earth rotation polarimetry. We do not detect linear polarization. Our analysis finds 3σ upper limits on the degree of polarization of 0.5 and 1.9 per cent at 239 and 348 GHz, respectively. We regard the influence of Faraday conversion as marginal, leading to expected circular polarizations ≲0.3 per cent. Assuming depolarization by a local Faraday screen, we constrain the rotation measure, as well as the fluctuations therein, to be ≳ 106 rad m−2. From this we estimate line‐of‐sight magnetic field strengths of ≳100 μG. Given the physical dimensions of 3C 84 and its observed structure, the Faraday screen appears to show prominent small‐scale structure, with ΔRM ≳ 106 rad m−2 on projected spatial scales ≲1 pc.

show abstract

B_{| |} \approx 100 μ

G are compatible to those found in the centre of the Milky Way, where field strengths in the range of ≈100 μG–1 mG have been reported (e.g.…”

Section: Discussionmentioning

confidence: 91%

A search for linear polarization in the active galactic nucleus 3C 84 at 239 and 348 GHz

Trippe

Bremer

Krichbaum

et al. 2012

Monthly Notices of the Royal Astronomical Society

Self Cite

View full text Add to dashboard Cite

show abstract

“…ALMA observations of 3C 273 reveal RM= (3.6 ± 0.3) × 10 5 rad m −2 (Hovatta et al 2018). Trippe et al (2012) reports RMs as large as 10 5 rad m −2 for AGN at wavelengths near millimeter wavelength. These large RMs are interpreted as originating from the accretion flow, relativistic jet, or the dense gas of the nuclear region (e.g., Mościbrodzka et al 2017).…”

Section: Discussionmentioning

confidence: 97%

ALMA Polarimetry of Sgr A*: Probing the Accretion Flow from the Event Horizon to the Bondi Radius

Bower¹,

Broderick

Dexter

et al. 2018

ApJ

View full text Add to dashboard Cite

Millimeter polarimetry of Sgr A* probes the linearly polarized emission region on a scale of ∼ 10 Schwarzschild radii (R S ) as well as the dense, magnetized accretion flow on scales out to the Bondi radius (∼ 10 5 R S ) through Faraday rotation. We present here multi-epoch ALMA Band 6 (230 GHz) polarimetry of Sgr A*. The results confirm a mean rotation measure, RM ≈ −5 × 10 5 rad m −2 , consistent with measurements over the past 20 years and support an interpretation of the RM as originating from a radiatively inefficient accretion flow (RIAF) withṀ ≈ 10 −8 M y −1 . Variability is observed for the first time in the RM on time scales that range from hours to months. The long-term variations may be the result of changes in the line of sight properties in a turbulent accretion flow. Short-term variations in the apparent RM are not necessarily the result of Faraday rotation and may be the result of complex emission and propagatation effects close to the black hole, some of which have been predicted in numerical modeling. We also confirm the detection of circular polarization at a mean value of −1.1 ± 0.2%. It is variable in amplitude on time scales from hours to months but the handedness remains unchanged from that observed in past centimeter-and millimeter-wavelength detections. These results provide critical constraints for the analysis and interpretation of Event Horizon Telescope data of Sgr A*, M87, and similar sources.

show abstract

“…The frequency dependence of RM has been used to constrain the location of the Faraday screen in several previous studies (e.g., Kang et al 2015;Lee et al 2015;Algaba 2013;Jorstad et al 2007;Trippe et al 2012). By assuming that the Faraday rotation generates within or in close proximity of the jet, a simple jet model yielded a frequency dependence of RM as |RM(ν)| ∝ν a , where ν is the observing frequency and the power index a corresponds to the power index of the evolution of electron density in jet as n e ∝ r −a , where n e is the electron density and r is the distance of the emitting region from the central engine.…”

Section: Discussionmentioning

confidence: 99%

Detection of millimeter-wavelength intraday variability in polarized emission from S5 0716+714

Lee

Kang

et al. 2016

A&A

View full text Add to dashboard Cite

We report the detection of millimeter-wavelength intraday variability in polarized emission from S5 0716+714 based on multifrequency polarization observations using the Korean VLBI Network (KVN) radio telescopes. The observations were conducted on November 7, 2013 at 22, 43, and 86 GHz in dual polarization using two 21 m radio telescopes belonging to KVN Yonsei and Ulsan. We found significant variations in the degree of linear polarization at 86 GHz and in polarization angle at 43 and 86 GHz during ∼10 h. We measured mean flux densities of 2.8 Jy, 2.8 Jy, and 2.7 Jy at 22, 43, and 86 GHz, respectively, with a flux modulation index ranging from 1.5% to 7.2% at the frequencies. The spectrum of the source is quite flat with spectral indices of −0.07 to 0.07 at 22−43 GHz and −0.23 to 0.04 at 43−86 GHz. The measured degree of the linear polarization ranges from 2.3% to 3.3% at 22 GHz from 0.9% to 2.2% at 43 GHz and from 0.4% to 4.0% at 86 GHz, yielding prominent variations at 86 GHz over 4−5 h. The linear polarization angle is in the range of 4• to 12• at 22 GHz, −39• to 81• at 43 GHz, and 66• to 119• at 86 GHz with a maximum rotation of 110 • at 43 GHz over ∼4 h. We estimated the Faraday rotation measures (RM) ranging from −9200 to 6300 rad m −2 between 22 and 43 GHz, and from −71 000 to 7300 rad m −2 between 43 and 86 GHz, respectively. The frequency dependency of RM was investigated, yielding a mean power-law index, a, of 2.0. This implies that the polarized emission from S5 0716+714 at 22−86 GHz moves through a Faraday screen in or near the jet of the source.

show abstract

The first IRAM/PdBI polarimetric millimeter survey of active galactic nuclei

Cited by 16 publications

References 46 publications

A search for linear polarization in the active galactic nucleus 3C 84 at 239 and 348 GHz

A search for linear polarization in the active galactic nucleus 3C 84 at 239 and 348 GHz

ALMA Polarimetry of Sgr A*: Probing the Accretion Flow from the Event Horizon to the Bondi Radius

Detection of millimeter-wavelength intraday variability in polarized emission from S5 0716+714

Contact Info

Product

Resources

About