Gas bulk motion in galaxy clusters

Tamura, Takayuki; Sekiya, Norio; Hayashida, Kentaro; Ueda, Shutaro; Nagai, Michiko

doi:10.1063/1.3696229

Cited by 16 publications

(22 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Substructures of the ICM are also known in X-ray observations (Briel et al 1991;Briel & Henry 1994;Sun et al 2002). Using the X-ray satellite Suzaku, Tamura et al (2011) estimated radial velocity difference of ∼ 1500 km s −1 in gas bulk motions of the substructures. There are two distinct ICM components with temperatures ∼ 7 keV and ∼ 4.5 keV (Sun et al 2002).…”

Section: Cluster Of Galaxies Abell 2256mentioning

confidence: 99%

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

Ozawa

Nakanishi

Akahori

et al. 2015

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

We report polarimetry results of a merging cluster of galaxies Abell 2256 with Karl G. Jansky Very Large Array (JVLA). We performed new observations with JVLA at S-band (2051-3947 MHz) and X-band (8051-9947 MHz) in the C array configuration, and detected significant polarized emissions from the radio relic, Source A, and Source B in this cluster. We calculated the total magnetic field strengths toward the radio relic using revised equipartition formula, which is 1.8-5.0 µG. With dispersions of Faraday rotation measure, magnetic-field strengths toward Sources A and B are estimated to be 0.63-1.26 µG and 0.11-0.21 µG, respectively. An extremely high degree of linear polarization, as high as ∼ 35 %, about a half of the maximum polarization, was detected toward the radio relic, which indicates highly ordered magnetic lines of force over the beam sizes (∼ 52 kpc).The fractional polarization of the radio relic decreases from ∼ 35 % to ∼ 20 % around 3 GHz as the frequency decreases and is nearly constant between 1.37 and 3 GHz. Both analyses with depolarization models and Faraday tomography suggest multiple depolarization components toward the radio relic and imply the existence of turbulent magnetic fields.

show abstract

Section: Cluster Of Galaxies Abell 2256mentioning

confidence: 99%

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

Ozawa

Nakanishi

Akahori

et al. 2015

Publications of the Astronomical Society of Japan

View full text Add to dashboard Cite

show abstract

“…Suzaku observed the radio relic region in A 2256 (OBSID: 801061010, Tamura et al 2011) with an exposure time of 95.2 ks. The satellite X-ray Imaging Spectrometer (XIS: Koyama et al 2007) has a very low detector background, which allows us to investigate weak X-ray emission targets such as cluster outskirts (see Reiprich et al 2013, for a review).…”

Section: X-ray Observations and Data Reductionmentioning

confidence: 99%

The radio relic in Abell 2256: overall spectrum and implications for electron acceleration

Trasatti

Akamatsu

Lovisari

et al. 2015

A&A

View full text Add to dashboard Cite

Context. Radio relics are extended synchrotron sources thought to be produced by shocks in the outskirts of merging galaxy clusters. The cluster Abell 2256 hosts one of the most intriguing examples in this class of sources. It has been found that this radio relic has a rather flat integrated spectrum at low frequencies that would imply an injection spectral index for the electrons that is inconsistent with the flattest allowed by the test particle diffusive shock acceleration (DSA). Aims. We aim at testing the origins of the radio relic in Abell 2256. Methods. We performed new high-frequency observations at 2273, 2640, and 4850 MHz. Combining these new observations with images available in the literature, we constrain the radio-integrated spectrum of the radio relic in Abell 2256 over the widest sampled frequency range collected so far for this class of objects (63−10 450 MHz). Moreover, we used X-ray observations of the cluster to check the temperature structure in the regions around the radio relic. Results. We find that the relic keeps an unusually flat behavior up to high frequencies. Although the relic integrated spectrum between 63 and 10 450 MHz is not inconsistent with a single power law with α 10 450 63 = 0.92 ± 0.02, we find hints of a steepening at frequencies >1400 MHz. The two frequency ranges 63−1369 MHz and 1369−10 450 MHz are, indeed, best represented by two different power laws, with α 1369 63 = 0.85 ± 0.01 and α 10 450 1369 = 1.00 ± 0.02. This broken power law would require special conditions to be explained in terms of test-particle DSA, e.g., non-stationarity of the spectrum, which would make the relic in A2256 a rather young system, and/or non-stationarity of the shock. On the other hand, the single power law would make of this relic the one with the flattest integrated spectrum known so far, even flatter than what is allowed in the test-particle approach to DSA. We find a rather low temperature ratio of T 2 /T 1 ∼ 1.7 across the G region of the radio relic and no temperature jump across the H region. However, in both regions projection effects might have affected the measurements, thereby reducing the contrast.

show abstract

“…A first significant detection of a bulk motion has been achieved with Suzaku for the merging subclump in A2256 (Tamura et al 2011). The radial velocity difference between the main cluster and the subclump is 1500±300±300 km s −1 (where the two sets of uncertainties refer to statistical and systematical ones, respectively).…”

Section: Observational Constraintsmentioning

confidence: 98%

“…This level of detail would provide a breakthrough in modelling the dynamics of the merging subclumps. Since the flux of A2256 subclump is comparable to that of the central region of similar size in A2256 (Tamura et al, 2011), the above calculations yield an approximate estimate of the expected velocity mapping precision level in the bright nearby cluster centres with XMS.…”

Section: A2256 and The Subclumpmentioning

confidence: 98%

See 1 more Smart Citation

Bulk motion measurements in clusters of galaxies with ATHENA‐like missions

Nevalainen¹

2013

Astron Nachr

View full text Add to dashboard Cite

The hierarchical formation of clusters of galaxies by accretion of material releases gravitational energy which dissipates into the intracluster gas. The process heats the material and generates gas turbulence and bulk motions and thus kinetic pressure. Mapping the velocity fields of the moving subunits would enable a new diagnostics tool for cluster formation studies and unbiased X-ray mass estimates. The required spatially resolved high resolution spectroscopy is not currently available. I demonstrate here the feasibility of detecting and mapping the velocities of the bulk motions using the Doppler shift of the Fe XXV Kα line with the proposed ATHENA satellite.

show abstract

Gas bulk motion in galaxy clusters

Cited by 16 publications

References 0 publications

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

JVLA S- and X-band polarimetry of the merging cluster Abell 2256

The radio relic in Abell 2256: overall spectrum and implications for electron acceleration

Bulk motion measurements in clusters of galaxies with ATHENA‐like missions

Contact Info

Product

Resources

About