Evidence for a pressure discontinuity at the position of the Coma relic from Planck Sunyaev–Zel'dovich effect data

Erler, Jens; Basu, Kaustuv; Trasatti, M.; Klein, U.; Bertoldi, F.

doi:10.1093/mnras/stu2750

Cited by 27 publications

(41 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using the GNFW model (Eq. (5)) fit for Coma (Erler et al 2015), we can confirm that the SZ contamination is indeed 10% at 5 GHz, so no current radio halo data has been seriously affected by this issue. However, because of the redshift independence of SZ brightness, the flux contamination for radio halos will increase rapidly with redshift.…”

Section: Side Topic: Sz Contamination For Radio Halosmentioning

confidence: 57%

“…CIZA J2248.8+5301 is not in the published Planck catalog because of its proximity to the Galactic plane, and some other known relic clusters are absent either because they are low mass systems or too compact. To keep uniformity over all the cluster mass calibration results, we extract Y 500 by fitting a GNFW model to an y-map extracted from the Planck all-sky data (see Erler et al 2015 for details). For CIZA J2248.8+5301 we obtain Y 500 = (3.6±0.1)×10 −3 arcmin 2 , which is about a factor 2 more than the GNFW model prediction based on the L X -derived mass (M X−ray 500 = 5.5 × 10 14 M ).…”

Section: The Sausage Relic In Ciza J22488+5301mentioning

confidence: 99%

“…In cluster simulations shocks are ubiquitous (e.g., Nuza et al 2012;Skillman et al 2013;Hong et al 2014), but their direct observation is still limited by small number statistics as detecting ICM shocks are hampered by their low surface brightness and projection effects, particularly in the cluster outskirts where the thermal signature is hard to detect in SZ or X-rays (e.g., Akamatsu & Kawahara 2013;Planck Collaboration X 2013;Erler et al 2015). Radio relics are elongated, diffuse synchrotron sources found in the cluster outskirts, have scale lengths on the order of ∼1 Mpc and are not associated with any AGN outflow (e.g., review by Feretti et al 2012).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The impact of the SZ effect on cm-wavelength (1–30 GHz) observations of galaxy cluster radio relics

Basu

Vazza

Erler

et al. 2016

A&A

View full text Add to dashboard Cite

Radio relics in galaxy clusters are believed to be associated with powerful shock fronts that originate during cluster mergers, and are a testbed for the acceleration of relativistic particles in the intracluster medium. Recently, radio relic observations have pushed into the cm-wavelength domain (1-30 GHz) where a break from the standard synchrotron power law spectrum has been found, most noticeably in the famous "Sausage" relic. Such spectral steepening is seen as an evidence for non-standard relic models, such as ones requiring seed electron population with a break in their energy spectrum. In this paper, however, we point to an important effect that has been ignored or considered insignificant while interpreting these new high-frequency radio data, namely the contamination due to the Sunyaev-Zel'dovich (SZ) effect that changes the observed synchrotron flux. Even though the radio relics reside in the cluster outskirts, the shock-driven pressure boost increases the SZ signal locally by roughly an order of magnitude. The resulting flux contamination for some well-known relics are non-negligible already at 10 GHz, and at 30 GHz the observed synchrotron fluxes can be diminished by a factor of several from their true values. At higher redshift the contamination gets stronger due to the redshift independence of the SZ effect. Interferometric observations are not immune to this contamination, since the change in the SZ signal occurs roughly at the same length scale as the synchrotron emission, although there the flux loss is less severe than single-dish observations. Besides presenting this warning to observers, we suggest that the negative contribution from the SZ effect can be regarded as one of the best evidence for the physical association between radio relics and shock waves. We present a simple analytical approximation for the synchrotron-to-SZ flux ratio, based on a theoretical radio relic model that connects the nonthermal emission to the thermal gas properties, and show that by measuring this ratio one can potentially estimate the relic magnetic fields or the particle acceleration efficiency.

show abstract

Section: Side Topic: Sz Contamination For Radio Halosmentioning

confidence: 57%

Section: The Sausage Relic In Ciza J22488+5301mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The impact of the SZ effect on cm-wavelength (1–30 GHz) observations of galaxy cluster radio relics

Basu

Vazza

Erler

et al. 2016

A&A

View full text Add to dashboard Cite

show abstract

“…Additionally, at the resolution of AMI-LA and CARMA the largest scale detectable is limited by Additionally the AMI-SA observations measured a total SZE flux < 2 mJy, indicating the SZE contribution will be extremely small ( 50 µ Jy, or less than ∼ 5 per cent of the relic flux density) at AMI-LA resolution and at the large cluster-centric distances the 'Sausage' and 'Toothbrush' relics are located (1.5 Mpc). Even though the relics are located far away from the cluster centre, Erler et al (2015) argue that shock compression could boost the SZE signal, leading to up to 30 per cent decrease at 10 GHz for Effelsberg observations of the relic of Abell 2256 . There is an important difference between our observations and Abell 2256: the relic in Abell 2256 is about 500 kpc from the cluster center, while the 'Sausage' and 'Toothbrush' clusters are 1.5 Mpc away from the cluster centre.…”

Section: Sunyaev-zeldovich Decrementmentioning

confidence: 97%

The widest frequency radio relic spectra: observations from 150 MHz to 30 GHz

Stroe

Shimwell

Rumsey³

et al. 2015

Mon. Not. R. Astron. Soc.

155

View full text Add to dashboard Cite

Radio relics are patches of diffuse synchrotron radio emission that trace shock waves. Relics are thought to form when intra-cluster medium electrons are accelerated by cluster merger induced shock waves through the diffusive shock acceleration mechanism. In this paper, we present observations spanning 150 MHz to 30 GHz of the 'Sausage' and 'Toothbrush' relics from the Giant Metrewave and Westerbork telescopes, the Karl G. Jansky Very Large Array, the Effelsberg telescope, the Arcminute Microkelvin Imager and Combined Array for Research in Millimeter-wave Astronomy. We detect both relics at 30 GHz, where the previous highest frequency detection was at 16 GHz. The integrated radio spectra of both sources clearly steepen above 2 GHz, at the 6σ significance level, supports the spectral steepening previously found in the 'Sausage' and the Abell 2256 relic. Our results challenge the widely adopted simple formation mechanism of radio relics and suggest more complicated models have to be developed that, for example, involve re-acceleration of aged seed electrons.

show abstract

“…band the Mach number can be obtained in an independent way from the pressure jump estimated from the thermal Sunyaev-Zel'dovich measurements (e.g. Erler et al 2015), and possible detection of the nonthermal SZE can give information on the properties of the electrons which are not depending on the magnetic field properties (see e.g. Colafrancesco & Marchegiani 2011 for the case of radio galaxies lobes).…”

Section: Discussionmentioning

confidence: 99%

The correlation between radio power and Mach number for radio relics in galaxy clusters

Colafrancesco

Marchegiani

Paulo

2017

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We discuss a new technique to constrain models for the origin of radio relics in galaxy clusters using the correlation between the shock Mach number and the radio power of relics. This analysis is carried out using a sample of relics with information on both the Mach numbers derived from X-ray observation, M X , and using spectral information from radio observations of the peak and the average values of the spectral index along the relic, M R . We find that there is a lack of correlation between M X and M R ; this result is an indication that the spectral index of the relic is likely not due to the acceleration of particles operated by the shock but it is related to the properties of a fossil electrons population. We also find that the available data on the correlation between the radio power P 1.4 and Mach numbers (M R and M X ) in relics indicate that neither the DSA nor the adiabatic compression can simply reproduce the observed P 1.4 − M correlations. Furthermore, we find that the radio power is not correlated with M X , whereas it is not possible to exclude a correlation with M R . This also indicates that the relic power is mainly determined by the properties of a fossil electron population rather than by the properties of the shock. Our results require either to consider models of shock (re)acceleration that go beyond the proposed scenarios of DSA and adiabatic compression at shocks, or to reconsider the origin of radio relics in terms of other physical scenarios.

show abstract

Evidence for a pressure discontinuity at the position of the Coma relic from Planck Sunyaev–Zel'dovich effect data

Cited by 27 publications

References 30 publications

The impact of the SZ effect on cm-wavelength (1–30 GHz) observations of galaxy cluster radio relics

The impact of the SZ effect on cm-wavelength (1–30 GHz) observations of galaxy cluster radio relics

The widest frequency radio relic spectra: observations from 150 MHz to 30 GHz

The correlation between radio power and Mach number for radio relics in galaxy clusters

Contact Info

Product

Resources

About