CINXE.COM

<!DOCTYPE html><html lang="en-US"><head><title>Just a moment...</title><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=Edge"><meta name="robots" content="noindex,nofollow"><meta name="viewport" content="width=device-width,initial-scale=1"><style>*{box-sizing:border-box;margin:0;padding:0}html{line-height:1.15;-webkit-text-size-adjust:100%;color:#313131;font-family:system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica Neue,Arial,Noto Sans,sans-serif,Apple Color Emoji,Segoe UI Emoji,Segoe UI Symbol,Noto Color Emoji}body{display:flex;flex-direction:column;height:100vh;min-height:100vh}.main-content{margin:8rem auto;max-width:60rem;padding-left:1.5rem}@media (width <= 720px){.main-content{margin-top:4rem}}.h2{font-size:1.5rem;font-weight:500;line-height:2.25rem}@media (width <= 720px){.h2{font-size:1.25rem;line-height:1.5rem}}#challenge-error-text{background-image:url(data:image/svg+xml;base64,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);background-repeat:no-repeat;background-size:contain;padding-left:34px}@media (prefers-color-scheme:dark){body{background-color:#222;color:#d9d9d9}}</style><meta http-equiv="refresh" content="390"></head><body class="no-js"><div class="main-wrapper" role="main"><div class="main-content"><noscript><div class="h2"><span id="challenge-error-text">Enable JavaScript and cookies to continue</span></div></noscript></div></div><script>(function(){window._cf_chl_opt={cvId: '3',cZone: "academic.oup.com",cType: 'managed',cRay: '918756bd8ef3fd80',cH: '6kiBwH7ZHZ481v06rsjV3Zn_zCVBfIlZPMnp5UbREqk-1740650541-1.2.1.1-ow5n0u2TFi6bnGoHXvmDBAThbfHGRN3hGH1Idcfo_sLMbn_TWOWaBHRpkuvsP4j_',cUPMDTk: "\/mnras\/article\/513\/2\/2239\/6568929?__cf_chl_tk=ol14rTQVu4DGriDf_dlesWqu_2gMbqzQZFDgutkMGTs-1740650541-1.0.1.1-N9YungP.4U0LLoTIATMhjR4EJhNbJRr0zt3WfKv8BVA",cFPWv: 'b',cITimeS: '1740650541',cTTimeMs: '1000',cMTimeMs: '390000',cTplC: 0,cTplV: 5,cTplB: 'cf',cK: "",fa: "\/mnras\/article\/513\/2\/2239\/6568929?__cf_chl_f_tk=ol14rTQVu4DGriDf_dlesWqu_2gMbqzQZFDgutkMGTs-1740650541-1.0.1.1-N9YungP.4U0LLoTIATMhjR4EJhNbJRr0zt3WfKv8BVA",md: "LQhdKq5Sco1hhcBd3w6IgvgqSPx3tmvifkjDoY8NTP4-1740650541-1.2.1.1-fgdTjEIkA2iLSelIksoARYzYRV8VJcFYJw9.CBlY5S6Bbk_hKPorhH.dsInX4frNQ_57oyt1Je.T_gD0I1VHFmKphxrrPwU9JW1hRrYBt9EQXMUpa8Qi_KXy0qYiKuMDL7Z01swpZu8uyCbfpTEhjgc365nobHQ909dD9T4VRyRqumbgFIV.yiAoFOf7kwOf7uvzl9Naub30cI.gXun5Cl_lssrNQLWlC0xrT1Rp7PZ02QHzyWliAh0pdHwfF2xjLBRq3.BduGMv1Na7bYXHd0Y9x9y1DBaTOGwE.s5FQgtTCb3UJ4z.oq.Ncc.HQVt0hQ.W90mbdnHahyNNnAMu1aWRXzqwLlJ.UGMcoKcs_GhmNa7cf9TWM8J3Rsc8wncHgDwh2IF8hvVq3lP_p7s8OGVgOHv3txpTRLET58x_eyL0vpT6iU3oB7VtVef4hJbSAbiSRHEXMSKcxxGOKjf7h7LKyT1mLihhYqfUuuMelnC5zdt2DRJsfD8BSkU1g2L0IzV9DIoQEyNjjOIB7NN.zeXiDyXsxZxGTET.qFq5h730zo3RdliUk1hYcqgz6uNw5EqY331zViEJGeIJl5B9pGnM9VzEvWy4g.Q5EijcLquFk8U15hA7oSpZPl7v5wmOn4XmKnj3zfiXiHRA_WyKU5DRyr9mPCvac_ZFJIytZCb5KBD6wSWZj0ILCMGLEae12PX2jnfjFZb95IDox1yjBzlHp.9F7nl2bVBWR_d5o0dc94Y.Bdca69pEIUlzNpnrZ.AKMDXhtP7J3itKFLfFgvADs8nVnh8qL0Z9MWyqPSRP.oaYJn4IoTdlCO9MgNo8ePcSrUHC1c4rxQZNNenMqImla8Zap_SHUj6RWJeY1h3mtivSuedaJ1cUv2DVaU9JqMLylwrsgiID9Y4LPe3m7TeOPr5mF5PkE.EN241Y4zyeCKUMIoPguWmrkG6TBDHHLCZfSANlOMslilOzoiyDCec5_XHRQm2iYqEwu0GwCaDQC7Kh3Rr5POmSipyL73b.yQimVN190kwqwl4QgQcbgF9Z5moEWnjkSBEQhM4tKhA3TZsiu_S9azQ2s66U0PUt35cbs.r1M7matS0DbxNzqCfOl1GxxHXxidhiJ0T57mYzEp_7jiL3qjiBi0B72hsPqkrLqbtgfQ9_YBI6SHHB7BmfEgXyM_ycLTViFACCmtewJT7b_QauwIdIdXnbhIVmkSKIj2OJq3FYM8OgzD3ZySrbfPi0rOWw9ymZLh0BOZjRqYpUAziRUROgYHEXIFTJTUDGgsEIRJjlA0HLFhsQP5.OvlPzPQocd4QShVWn5FVkhI4HGWJqsYlYDR7N.j3k7eus5LNYOzoM0iHY1C7d1HsJNhYPGm5rQ_u88hc1Npzu.KGaYzMQOewxT4KMQUg7Poq3GhYLVlQbS6B8mB5F3SrPA.ZugS_lWsvoHhUMHsjZXOKIpCvhxICn7c85iJSFqc2qD8kquoN3ETY9gWj21B4iEg4edR9EkfSjwz7n3z_RpzbLwSDYa7mCQIRIix_lVFjuTzfAUWaZUTlBcUZ5OeMsto_LS4Mf7PuQ.RbMwViWWkSTfWbuXIhY0ljfYmaG9n32BEuCVch7RGdNBnt2oDEJDJC.YxHiwk9iUI8Q0ZVtLgjV_L5FMtpUpC.OEDPyDLgEVwzcvO9pxED3kNxSzuW8Oxn9YcigR1w5vSZK7U1Ss_b5xoAL6Jq5NazmT0fakQhQENCfMvGJCdTlRF7dRAYzcxWtZpFmVDQU_HONk81vq3BTaxrq7tkNnNF7JoxFORqDmWqFX6urLaN.Qd0K4lXDpOJfbSCVjNCvwPCAOdbaKAHDR04v7LK5rFr7_NzjH.7CH0HTze9PMyLnU2jZtAkdPWg08g1gRtLJzPeruhSez4e_4_Yn1bNSqn_arDJQY7IHIrsop9H3qgXDK2xZ_dyUcFbGaXcr2qCKYNHu_e.dDaiGzB_4AH_x4nFbTzgrzq_TOFgUWMBzYHiT4AaS1.cHoFhOxMNFwh.LwKk4MjzNO2nNvnjUPFyLPJzAEJnjE5jSY91q6HiPFTJoxnD4k1u1gxn5KlRu93OMtLkmwP95JdpjexoQESWD0iEVJh0xs72jnHoPAq8xg7jEMw.RSHEsSfND2d8K49GndRIJZkauG9HVR4oolwM2rgMSanWuRc9UZ2PYjLskDJNNDBxR7pP2tZQdEFbQWMdg_MZruFMjQ_z7sK7GWUPpqowta1diaxMDzY_x1saEdK.4UDpO4X8ZhXWrBB64tVSU.eX1o5Ox8bll_jngPdT7c1UFvk1BsMwHyPHh5V9le8JaGr3_8_d7tbAbo8w.tzsrcy4FknZJBPtA9lqly2dLhJNdYFAAK1INFeu_j_gSyRTq_RKJG1uNAhtfuX8HSZEajeNP_6lasaEl69G7zkDTbMrSVrEqdLhTk458qHdzo0U3GQkNmyk2hDDjT9ePNTWJtkiHPM7AhiRKkmcAUAvw9fKYqxjkfmfUpHCSNDOoChjBhoYKcISdvIrjzGM6tgDQmFyreLqdJhJRbyk3QHcJNEpLR1BLWdRUZ8EtmCYDD_C58uFnVGboMcDPWTAb1rE20Lac7R4",mdrd: "3lRIB5kzNloKn55ML2C3Z4EAJDqAWppoweKP2iVEuKI-1740650541-1.2.1.1-zO73MDcM1kpdnwRk_..KBFzZoEzBfzIadFQ0L1N15S4yOUKldu.V6qBGzIxIcwFrwPInhAfkDEdPxeBW37.MVep7M3ojbgKPhV12x9E_TamaHCuNZzaAIYjKIkdEsQ6ZwqHZmv1bP87r8wUI_a5ILw66IgrS5BPcwEhPk3wlMqWRFEr8bhF_sYflkOFSNjY3daDE6bo0Y7Tag9DdGv21xhy2SgsJPAoIRadVqhwkyatKQlnshmaNE.oKa_2.drR7MZ6C6BYXK8hCTujqbEkK6QJ0Om8ewQKzl2BPjS78ca4aMSSaeKuHKwEsdELdWiavVcLRTetsPmpngMNl9utqUksiKDZfrJ1bXrhODdz3qKB1dZi9UuYL2MwceW1zwyvYmiYFpf83XdfwUNJTER4F7z3Juf2atUD1EryAlC6BtH5dTvPOF8_5FrJoBP39tz_h3rOuxLawK3OcZjvWpUDLewVNjTypYxt6o0PwK6kFk10C4ooSk6KJPIaS8uT29KEU3NAmkZPg6tZSX5EOtMyf930g5YilQtETSETke_UHPvQtY62kNxfCaoBZJnyfnZrsIqAZJPZHmYWXQMMqCy1lfbtPlvVmn2urO50asVLiYOq1f6sWJJzvxrxsRF8NkTVGPZJUD04Y_f9QYc9aVztUre2_X02499O8NUiMUM.2eVPZmzP93dzGDhYn1gOUJaKVBLR82Zghn3rwNRV8X5klVixRB2V4BnH795WB93VIXcPjnyN6Lu1fL0ossdIUQq4KgASyJCcSHlys4BzqvtfllYjBHi2bwMQy79nYPac3dNKMptaLVinDCLJ8Zn8xZj3xXbmd4c4cOT9DNbBeG1xqwxUorWr8ritpgbC_oMDduwFj4gsYFaILSpc217eBq0cAan5Yt8YBitkEQ45roubIyW9h3yPGhs27kZVA_g1f6SsLeAje0mwcrE5KFj_L0xQtpmjyn6VucnqhH8VJs6n2upZddQDl9c2psAKRV7MC84.dvjiThxmhV.z9qrAhEPpatOj2KNQ6VS6K92y8wR8.u.08_Y5WYlm3LiTxXbFa8BEIbmo5LUXJsWW2G3nrZTGrYGWISgvYOhC10tuYWOOubyc7KAq8OIjZsCfCdLTUW1YzpebxOX1cRs2G3pq.roOXLN2mRmm8sgSzsm7Rr9kfGm9g0tsbXtk28ouEPcqWg5laPDcMrMmh0PYnzNyD_p5x2xP88pFHXlFpyzYxJNiQI8547IWxXdNN_MUGm6.7CfnJrV2TjWe_0OK1JkTnagovHtK8mP1GiVHrTVZ1Y.jz8BcWYP4Bg7Cn2UPayQ4Mh2RqRYpLpAUN00U8VaPl81Pel8KUVbWQwZBwXC1NoYj0XzO.KgbIxYiAIiupQq5gq9EChOrpd4aGAfrPzJRdFOmEK51C.224w9fcCH.r_rrPMgQdm18vcphqmWopXUi_tvmeHeI1x_URfv7RS5.tJo2.Jqh9pJd.amkumYoiSnVzxp8VmTSDAndp1KLhvGsYhYwqBFTMwDuYgL2T4Y9se.XnqQJ.393d5applRJ7uwq9.5ke7Wg88m8T7FKQ_r7ZwCvXpK3WhR8uBZfPOk7pJVxqO6bOXmqouhKNdMZIbjp5iEFDDA7Mo89iqpx5gpUTS0P_VbMkEcSwz8Sf34XuCmiedC7L.dKlZ87.ZqsdhQLwRfGcPL8uGObI1eeNcXpUdJrWD4wcL8bHKeK1U7bJRRIh3BQSEuSWPEjMbc8UNe542uZxyEL57Tc.nCsX.RF0e75HYIKwRdkXAqw7_ncEgJJM5UsYTec41MowH9uIMyipSrpJj0FaG_qo7.6nRRCvl1giLO8f0MZRdHwBbGqwNnJp3mUIe9pI7H4baub0RNKkMT0W5vZpSi.RPhLYGW3miSHDubKOLIltflhyH1EXu2RxLUzbE2S0rDJtow.O9Abl2PtNEax9ii8PRFXOL558ogLv0ZTFxmoRQ12WqegPHKeP"};var cpo = document.createElement('script');cpo.src = '/cdn-cgi/challenge-platform/h/b/orchestrate/chl_page/v1?ray=918756bd8ef3fd80';window._cf_chl_opt.cOgUHash = location.hash === '' && location.href.indexOf('#') !== -1 ? '#' : location.hash;window._cf_chl_opt.cOgUQuery = location.search === '' && location.href.slice(0, location.href.length - window._cf_chl_opt.cOgUHash.length).indexOf('?') !== -1 ? '?' : location.search;if (window.history && window.history.replaceState) {var ogU = location.pathname + window._cf_chl_opt.cOgUQuery + window._cf_chl_opt.cOgUHash;history.replaceState(null, null, "\/mnras\/article\/513\/2\/2239\/6568929?__cf_chl_rt_tk=ol14rTQVu4DGriDf_dlesWqu_2gMbqzQZFDgutkMGTs-1740650541-1.0.1.1-N9YungP.4U0LLoTIATMhjR4EJhNbJRr0zt3WfKv8BVA" + window._cf_chl_opt.cOgUHash);cpo.onload = function() {history.replaceState(null, null, ogU);}}document.getElementsByTagName('head')[0].appendChild(cpo);}());</script></body></html>