تقرير
The diffuse radio emission in the high-redshift cluster PSZ2 G091.83+26.11: total intensity and polarisation analysis with Very Large Array 1-4 GHz observations
العنوان: | The diffuse radio emission in the high-redshift cluster PSZ2 G091.83+26.11: total intensity and polarisation analysis with Very Large Array 1-4 GHz observations |
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المؤلفون: | Di Gennaro, G., Brüggen, M., van Weeren, R. J., Simionescu, A., Brunetti, G., Cassano, R., Forman, W. R., Hoeft, M., Ignesti, A., Röttgering, H. J. A., Shimwell, T. W. |
المصدر: | A&A 675, A51 (2023) |
سنة النشر: | 2023 |
المجموعة: | Astrophysics |
مصطلحات موضوعية: | Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics |
الوصف: | We present the peculiar case of PSZ2G091.83+26.11 at z=0.822. This cluster hosts a Mpc-scale radio halo and an elongated radio source, whose location with the respect to the intracluster medium (ICM) distribution and to the cluster centre is not consistent with a simple merger scenario. We use VLA data at 1-4 GHz to investigate the spectral and polarisation properties of the diffuse radio emission. We combine them with previously published data from LOFAR n the 120-168 MHz band, and from the uGMRT at 250-500 and 550-900 MHz. We also complement the radio data with Chandra X-ray observations to compare the thermal and non-thermal emission of the cluster. The elongated radio emission is visible up to 3.0 GHz and has an integrated spectral index of $-1.24\pm0.03$, with a steepening from $-0.89\pm0.03$ to $-1.39\pm0.03$. These values correspond to Mach numbers $\mathcal{M}_{\rm radio,int}=3.0\pm0.19$ and $\mathcal{M}_{\rm radio,inj}=2.48\pm0.15$. Chandra data reveals a surface brightness discontinuity at the location of the radio source, with a compression factor of $\mathcal{C}=2.22^{+0.39}_{-0.30}$ (i.e. $\mathcal{M}_{\rm Xray}=1.93^{+0.42}_{-0.32}$). We also find that the source is polarised at GHz frequencies. We estimate an intrinsic polarisation fraction of $\sim0.2$, a Rotation Measure of $\sim50~{\rm rad~m^{-2}}$ (including the Galactic contribution) and an external depolarisation of $\sim60~{\rm rad~m^{-2}}$. The $B$-vectors are aligned with the major axis of the source, suggesting magnetic field compression. Hence, we classify this source as a radio relic. We also find a linear/super-linear correlation between the non-thermal and thermal emission. We propose an off-axis merger and/or multiple merger events to explain the position and orientation of the relic. Given the properties of the radio relic, we speculate that PSZ2G091.83+26.11 is in a fairly young merger state. Comment: 21 pages, 17 figures, 9 tables; accepted for publication in Astronomy & Astrophysics |
نوع الوثيقة: | Working Paper |
DOI: | 10.1051/0004-6361/202345905 |
URL الوصول: | http://arxiv.org/abs/2304.05893 |
رقم الأكسشن: | edsarx.2304.05893 |
قاعدة البيانات: | arXiv |
DOI: | 10.1051/0004-6361/202345905 |
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