<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="static/style.xsl"?><OAI-PMH xmlns="http://www.openarchives.org/OAI/2.0/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/ http://www.openarchives.org/OAI/2.0/OAI-PMH.xsd"><responseDate>2026-04-14T04:35:57Z</responseDate><request verb="GetRecord" identifier="oai:www.recercat.cat:2445/218358" metadataPrefix="marc">https://recercat.cat/oai/request</request><GetRecord><record><header><identifier>oai:recercat.cat:2445/218358</identifier><datestamp>2025-12-05T16:13:54Z</datestamp><setSpec>com_2072_1057</setSpec><setSpec>col_2072_478904</setSpec><setSpec>col_2072_478917</setSpec></header><metadata><record xmlns="http://www.loc.gov/MARC21/slim" xmlns:dcterms="http://purl.org/dc/terms/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:doc="http://www.lyncode.com/xoai" xsi:schemaLocation="http://www.loc.gov/MARC21/slim http://www.loc.gov/standards/marcxml/schema/MARC21slim.xsd">
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      <subfield code="a">Arita, J.</subfield>
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      <subfield code="a">Kashikawa, N.</subfield>
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      <subfield code="a">Matsuoka, Y.</subfield>
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      <subfield code="a">He, W.</subfield>
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      <subfield code="a">Ito, K.</subfield>
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      <subfield code="a">Liang, Y.</subfield>
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      <subfield code="a">Ishimoto, R.</subfield>
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      <subfield code="a">Yoshioka, T.</subfield>
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      <subfield code="a">Takeda, Y.</subfield>
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      <subfield code="a">Iwasawa, Kazushi</subfield>
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      <subfield code="a">Onoue, M.</subfield>
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      <subfield code="a">Toba, Y.</subfield>
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      <subfield code="a">Imanishi, M.</subfield>
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      <subfield code="c">2025-01-31T16:54:48Z</subfield>
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      <subfield code="c">2025-01-31T16:54:48Z</subfield>
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      <subfield code="c">2025-01-31T16:54:48Z</subfield>
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      <subfield code="a">We present, for the first time, dark matter halo (DMH) mass measurement of quasars at z ∼ 6 based on a clustering analysis of 107 quasars. Spectroscopically identified quasars are homogeneously extracted from the Hyper Suprime-Cam Strategic Survey Program wide layer over 891 deg2. We evaluate the clustering strength by three different autocorrelation functions: projected correlation function, angular correlation function, and redshift–space correlation function. The DMH mass of quasars at z ∼ 6 is evaluated as with the bias parameter b = 20.8 ± 8.7 by the projected correlation function. The other two estimators agree with these values; though, each uncertainty is large. The DMH mass of quasars is found to be nearly constant ∼1012.5h−1M⊙ throughout cosmic time, suggesting that there is a characteristic DMH mass where quasars are always activated. As a result, quasars appear in the most massive halos at z ∼ 6, but in less extreme halos thereafter. The DMH mass does not appear to exceed the upper limit of 1013h−1M⊙, which suggests that most quasars reside in DMHs with  across most of the cosmic time. Our results supporting a significant increasing bias with redshift are consistent with the bias evolution model with inefficient active galactic nucleus feedback at z ∼ 6. The duty cycle (fduty) is estimated as 0.019 ± 0.008 by assuming that DMHs in some mass interval can host a quasar. The average stellar mass is evaluated from stellar-to-halo mass ratio as, which is found to be consistent with [C ii] observational results.</subfield>
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      <subfield code="a">Quàsars</subfield>
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      <subfield code="a">Forats negres (Astronomia)</subfield>
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      <subfield code="a">Galàxies</subfield>
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      <subfield code="a">Quasars</subfield>
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      <subfield code="a">Black holes (Astronomy)</subfield>
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      <subfield code="a">Galaxies</subfield>
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      <subfield code="a">Subaru High-z Exploration of Low-luminosity Quasars (SHELLQs). XVIII. The Dark Matter Halo Mass of Quasars at z ∼ 6</subfield>
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