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 Aya Kubota",
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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 - Kubota, Aya

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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