Browsing by Author "Vacca, Valentina"

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    A high-resolution view of the filament of gas between Abell 399 and Abell 401 from the Atacama Cosmology Telescope and MUSTANG-2
    (2022) Hincks, Adam D.; Radiconi, Federico; Romero, Charles; Madhavacheril, Mathew S.; Mroczkowski, Tony; Austermann, Jason E.; Barbavara, Eleonora; Battaglia, Nicholas; Battistelli, Elia; Bond, J. Richard; Calabrese, Erminia; de Bernardis, Paolo; Devlin, Mark J.; Dicker, Simon R.; Duff, Shannon M.; Duivenvoorden, Adriaan J.; Dunkley, Jo; Dunner, Rolando; Gallardo, Patricio A.; Govoni, Federica; Hill, J. Colin; Hilton, Matt; Hubmayr, Johannes; Hughes, John P.; Lamagna, Luca; Lokken, Martine; Masi, Silvia; Mason, Brian S.; McMahon, Jeff; Moodley, Kavilan; Murgia, Matteo; Naess, Sigurd; Page, Lyman; Piacentini, Francesco; Salatino, Maria; Sarazin, Craig L.; Schillaci, Alessandro; Sievers, Jonathan L.; Sifon, Cristobal; Staggs, Suzanne; Ullom, Joel N.; Vacca, Valentina; Van Engelen, Alexander; Vissers, Michael R.; Wollack, Edward J.; Xu, Zhilei
    We report a significant detection of the hot intergalactic medium in the filamentary bridge connecting the galaxy clusters Abell 399 and Abell 401. This result is enabled by a low-noise, high-resolution map of the thermal Sunyaev-Zeldovich signal from the Atacama Cosmology Telescope (ACT) and Planck satellite. The ACT data provide the 1.65 arcmin resolution that allows us to clearly separate the profiles of the clusters, whose centres are separated by 37 arcmin, from the gas associated with the filament. A model that fits for only the two clusters is ruled out compared to one that includes a bridge component at > 5 sigma. Using a gas temperature determined from Suzaku X-ray data, we infer a total mass of (3.3 +/- 0.7) x 10(14) M-circle dot associated with the filament, comprising about 8 per cent of the entire Abell 399-Abell 401 system. We fit two phenomenological models to the filamentary structure; the favoured model has a width transverse to the axis joining the clusters of similar to 1.9 Mpc. When combined with the Suzaku data, we find a gas density of (0.88 +/- 0.24) x 10(-4) cm(-3), considerably lower than previously reported. We show that this can be fully explained by a geometry in which the axis joining Abell 399 and Abell 401 has a large component along the line of sight, such that the distance between the clusters is significantly greater than the 3.2 Mpc projected separation on the plane of the sky. Finally, we present initial results from higher resolution (12.7 arcsec effective) imaging of the bridge with the MUSTANG-2 receiver on the Green Bank Telescope.
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    The thermal and non-thermal components within and between galaxy clusters Abell 399 and Abell 401
    (2022) Radiconi, Federico; Vacca, Valentina; Battistelli, Elia; Bonafede, Annalisa; Capalbo, Valentina; Devlin, Mark J.; Di Mascolo, Luca; Feretti, Luigina; Gallardo, Patricio A.; Gill, Ajay; Giovannini, Gabriele; Govoni, Federica; Guan, Yilun; Hilton, Matt; Hincks, Adam D.; Hughes, John P.; Iacobelli, Marco; Isopi, Giovanni; Loi, Francesca; Moodley, Kavilan; Mroczkowski, Tony; Murgia, Matteo; Orru, Emanuela; Paladino, Rosita; Partridge, Bruce; Sarazin, Craig L.; Scherer, Jack Orlowski; Sifon, Cristobal; Vargas, Cristian; Vazza, Franco; Wollack, Edward J.
    We measure the local correlation between radio emission and Compton-y signal across two galaxy clusters, Abell 399 and Abell 401, using maps from the Low Frequency Array and the Atacama Cosmology Telescope + Planck. These data sets allow us to make the first measurement of this kind at similar to arcmin resolution. We find that the radio brightness scales as F-radio proportional to y(1.5) for Abell 401 and F-radio proportional to y(2.8) for Abell 399. Furthermore, using XMM-Newton data, we derive a sublinear correlation between radio and X-ray brightness for both the clusters (F-radio proportional to F-X(0.7)). Finally, we correlate the Compton-y and X-ray data, finding that an isothermal model is consistent with the cluster profiles, y proportional to F-X(0.5). By adopting an isothermal-beta model, we are able, for the first time, to jointly use radio, X-ray, and Compton-y data to estimate the scaling index for the magnetic field profile, B(r) proportional to n(e)(r)(eta) in the injection and re-acceleration scenarios. Applying this model, we find that the combined radio and Compton-y signal exhibits a significantly tighter correlation with the X-ray across the clusters than when the data sets are independently correlated. We find eta similar to 0.6-0.8. These results are consistent with the upper limit we derive for the scaling index of the magnetic field using rotation measure values for two radio galaxies in Abell 401. We also measure the radio, Compton-y, and X-ray correlations in the filament between the clusters but conclude that deeper data are required for a convincing determination of the correlations in the filament.