Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS

Hitomi Collaboration

    Research output: Contribution to journalArticle

    7 Citations (Scopus)

    Abstract

    Thanks to its high spectral resolution (∼5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV Heα line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ∼1.3 in the inner ∼30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.

    Original languageEnglish
    Article numberpsx127
    JournalPublications of the Astronomical Society of Japan
    Volume70
    Issue number2
    DOIs
    Publication statusPublished - 2018 Mar 1

    Fingerprint

    spectrometer
    scattering
    spectrometers
    gases
    gas
    emissivity
    x rays
    prediction
    predictions
    plasma
    ion
    spectral resolution
    radiative transfer
    metallicity
    ions
    anisotropy
    physical property
    physical properties
    retarding
    galaxies

    Keywords

    • Galaxies: clusters: individual (Perseus Cluster)
    • Galaxies: clusters: intracluster medium
    • X-rays: galaxies: clusters

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science

    Cite this

    Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS. / Hitomi Collaboration.

    In: Publications of the Astronomical Society of Japan, Vol. 70, No. 2, psx127, 01.03.2018.

    Research output: Contribution to journalArticle

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    title = "Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS",
    abstract = "Thanks to its high spectral resolution (∼5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV Heα line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ∼1.3 in the inner ∼30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.",
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    author = "{Hitomi Collaboration} and Felix Aharonian and Hiroki Akamatsu and Fumie Akimoto and Allen, {Steven W.} and Lorella Angelini and Marc Audard and Hisamitsu Awaki and Magnus Axelsson and Aya Bamba and Bautz, {Marshall W.} and Roger Blandford and Brenneman, {Laura W.} and Brown, {Gregory V.} and Esra Bulbul and Cackett, {Edward M.} and Maria Chernyakova and Chiao, {Meng P.} and Coppi, {Paolo S.} and Elisa Costantini and {De Plaa}, Jelle and {De Vries}, {Cor P.} and {Den Herder}, {Jan Willem} and Chris Done and Tadayasu Dotani and Ken Ebisawa and Eckart, {Megan E.} and Teruaki Enoto and Yuichiro Ezoe and Fabian, {Andrew C.} and Carlo Ferrigno and Foster, {Adam R.} and Ryuichi Fujimoto and Yasushi Fukazawa and Maki Furukawa and Akihiro Furuzawa and Massimiliano Galeazzi and Gallo, {Luigi C.} and Poshak Gandhi and Margherita Giustini and Andrea Goldwurm and Liyi Gu and Matteo Guainazzi and Yoshito Haba and Kouichi Hagino and Kenji Hamaguchi and Harrus, {Ilana M.} and Isamu Hatsukade and Katsuhiro Hayashi and Takayuki Hayashi and Jun Kataoka",
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    T1 - Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS

    AU - Hitomi Collaboration

    AU - Aharonian, Felix

    AU - Akamatsu, Hiroki

    AU - Akimoto, Fumie

    AU - Allen, Steven W.

    AU - Angelini, Lorella

    AU - Audard, Marc

    AU - Awaki, Hisamitsu

    AU - Axelsson, Magnus

    AU - Bamba, Aya

    AU - Bautz, Marshall W.

    AU - Blandford, Roger

    AU - Brenneman, Laura W.

    AU - Brown, Gregory V.

    AU - Bulbul, Esra

    AU - Cackett, Edward M.

    AU - Chernyakova, Maria

    AU - Chiao, Meng P.

    AU - Coppi, Paolo S.

    AU - Costantini, Elisa

    AU - De Plaa, Jelle

    AU - De Vries, Cor P.

    AU - Den Herder, Jan Willem

    AU - Done, Chris

    AU - Dotani, Tadayasu

    AU - Ebisawa, Ken

    AU - Eckart, Megan E.

    AU - Enoto, Teruaki

    AU - Ezoe, Yuichiro

    AU - Fabian, Andrew C.

    AU - Ferrigno, Carlo

    AU - Foster, Adam R.

    AU - Fujimoto, Ryuichi

    AU - Fukazawa, Yasushi

    AU - Furukawa, Maki

    AU - Furuzawa, Akihiro

    AU - Galeazzi, Massimiliano

    AU - Gallo, Luigi C.

    AU - Gandhi, Poshak

    AU - Giustini, Margherita

    AU - Goldwurm, Andrea

    AU - Gu, Liyi

    AU - Guainazzi, Matteo

    AU - Haba, Yoshito

    AU - Hagino, Kouichi

    AU - Hamaguchi, Kenji

    AU - Harrus, Ilana M.

    AU - Hatsukade, Isamu

    AU - Hayashi, Katsuhiro

    AU - Hayashi, Takayuki

    AU - Kataoka, Jun

    PY - 2018/3/1

    Y1 - 2018/3/1

    N2 - Thanks to its high spectral resolution (∼5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV Heα line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ∼1.3 in the inner ∼30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.

    AB - Thanks to its high spectral resolution (∼5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV Heα line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of ∼1.3 in the inner ∼30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, Heβ, Lyα) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.

    KW - Galaxies: clusters: individual (Perseus Cluster)

    KW - Galaxies: clusters: intracluster medium

    KW - X-rays: galaxies: clusters

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