A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission
Reconstruction techniques for intrinsic quasar continua are crucial for the precision study of Lyman-$\alpha$ (Ly-$\alpha$) and Lyman-$\beta$ (Ly-$\beta$) transmission at $z>5.0$, where the $\lambda
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| creator | Bosman, S. E. I Ďurovčíková, D Davies, F. B Eilers, A. C |
| description | Reconstruction techniques for intrinsic quasar continua are crucial for the
precision study of Lyman-$\alpha$ (Ly-$\alpha$) and Lyman-$\beta$ (Ly-$\beta$)
transmission at $z>5.0$, where the $\lambda |
| doi_str_mv | 10.48550/arxiv.2006.10744 |
| format | Article |
| fullrecord | <record><control><sourceid>arxiv_GOX</sourceid><recordid>TN_cdi_arxiv_primary_2006_10744</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><sourcerecordid>2006_10744</sourcerecordid><originalsourceid>FETCH-arxiv_primary_2006_107443</originalsourceid><addsrcrecordid>eNqFjrEOgjAURbs4GPUDnOzASi0K6mqMxsHRkYQ8a5Em0MJrIeLXC4S4Ot3ck5ubQ8gy4Cw8RBFfA75Vwzac71jA92E4Jc2RClOUgMoaTU1KqxosIJWFslZ1CKUw2jqsheurkyLTqqqlpalB6n3il6wixj16awvQvhdDXmbgUdDPH3pI1xGHoO14OyeTFHIrF2POyOpyvp-u_mCYlKgKwDbpTZPBdPt_8QXD8UnK</addsrcrecordid><sourcetype>Open Access Repository</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype></control><display><type>article</type><title>A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission</title><source>arXiv.org</source><creator>Bosman, S. E. I ; Ďurovčíková, D ; Davies, F. B ; Eilers, A. C</creator><creatorcontrib>Bosman, S. E. I ; Ďurovčíková, D ; Davies, F. B ; Eilers, A. C</creatorcontrib><description><![CDATA[Reconstruction techniques for intrinsic quasar continua are crucial for the
precision study of Lyman-$\alpha$ (Ly-$\alpha$) and Lyman-$\beta$ (Ly-$\beta$)
transmission at $z>5.0$, where the $\lambda<1215 A$ emission of quasars is
nearly completely absorbed. While the number and quality of spectroscopic
observations has become theoretically sufficient to quantify Ly-$\alpha$
transmission at $5.0<z<6.0$ to better than $1\%$, the biases and uncertainties
arising from predicting the unabsorbed continuum are not known to the same
level. In this paper, we systematically evaluate eight reconstruction
techniques on a unified testing sample of $2.7<z<3.5$ quasars drawn from eBOSS.
The methods include power-law extrapolation, stacking of neighbours, and six
variants of Principal Component Analysis (PCA) using direct projection, fitting
of components, or neural networks to perform weight mapping. We find that
power-law reconstructions and the PCA with fewest components and smallest
training sample display the largest biases in the Ly-$\alpha$ forest
($-9.58\%/+8.22\%$ respectively). Power-law extrapolations have larger scatters
than previously assumed of $+13.1\%/-13.2\%$ over Ly-$\alpha$ and
$+19.9\%/-20.1\%$ over Ly-$\beta$. We present two new PCAs which achieve the
best current accuracies of $9\%$ for Ly-$\alpha$ and $17\%$ for Ly-$\beta$. We
apply the eight techniques after accounting for wavelength-dependent biases and
scatter to a sample $19$ quasars at $z>5.7$ with IR X-Shooter spectroscopy,
obtaining well-characterised measurements for the mean flux transmission at
$4.7<z<6.3$. Our results demonstrate the importance of testing and, when
relevant, training, continuum reconstruction techniques in a systematic way.]]></description><identifier>DOI: 10.48550/arxiv.2006.10744</identifier><language>eng</language><subject>Physics - Astrophysics of Galaxies ; Physics - Cosmology and Nongalactic Astrophysics</subject><creationdate>2020-06</creationdate><rights>http://arxiv.org/licenses/nonexclusive-distrib/1.0</rights><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>228,230,776,881</link.rule.ids><linktorsrc>$$Uhttps://arxiv.org/abs/2006.10744$$EView_record_in_Cornell_University$$FView_record_in_$$GCornell_University$$Hfree_for_read</linktorsrc><backlink>$$Uhttps://doi.org/10.1093/mnras/stab572$$DView published paper (Access to full text may be restricted)$$Hfree_for_read</backlink><backlink>$$Uhttps://doi.org/10.48550/arXiv.2006.10744$$DView paper in arXiv$$Hfree_for_read</backlink></links><search><creatorcontrib>Bosman, S. E. I</creatorcontrib><creatorcontrib>Ďurovčíková, D</creatorcontrib><creatorcontrib>Davies, F. B</creatorcontrib><creatorcontrib>Eilers, A. C</creatorcontrib><title>A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission</title><description><![CDATA[Reconstruction techniques for intrinsic quasar continua are crucial for the
precision study of Lyman-$\alpha$ (Ly-$\alpha$) and Lyman-$\beta$ (Ly-$\beta$)
transmission at $z>5.0$, where the $\lambda<1215 A$ emission of quasars is
nearly completely absorbed. While the number and quality of spectroscopic
observations has become theoretically sufficient to quantify Ly-$\alpha$
transmission at $5.0<z<6.0$ to better than $1\%$, the biases and uncertainties
arising from predicting the unabsorbed continuum are not known to the same
level. In this paper, we systematically evaluate eight reconstruction
techniques on a unified testing sample of $2.7<z<3.5$ quasars drawn from eBOSS.
The methods include power-law extrapolation, stacking of neighbours, and six
variants of Principal Component Analysis (PCA) using direct projection, fitting
of components, or neural networks to perform weight mapping. We find that
power-law reconstructions and the PCA with fewest components and smallest
training sample display the largest biases in the Ly-$\alpha$ forest
($-9.58\%/+8.22\%$ respectively). Power-law extrapolations have larger scatters
than previously assumed of $+13.1\%/-13.2\%$ over Ly-$\alpha$ and
$+19.9\%/-20.1\%$ over Ly-$\beta$. We present two new PCAs which achieve the
best current accuracies of $9\%$ for Ly-$\alpha$ and $17\%$ for Ly-$\beta$. We
apply the eight techniques after accounting for wavelength-dependent biases and
scatter to a sample $19$ quasars at $z>5.7$ with IR X-Shooter spectroscopy,
obtaining well-characterised measurements for the mean flux transmission at
$4.7<z<6.3$. Our results demonstrate the importance of testing and, when
relevant, training, continuum reconstruction techniques in a systematic way.]]></description><subject>Physics - Astrophysics of Galaxies</subject><subject>Physics - Cosmology and Nongalactic Astrophysics</subject><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2020</creationdate><recordtype>article</recordtype><sourceid>GOX</sourceid><recordid>eNqFjrEOgjAURbs4GPUDnOzASi0K6mqMxsHRkYQ8a5Em0MJrIeLXC4S4Ot3ck5ubQ8gy4Cw8RBFfA75Vwzac71jA92E4Jc2RClOUgMoaTU1KqxosIJWFslZ1CKUw2jqsheurkyLTqqqlpalB6n3il6wixj16awvQvhdDXmbgUdDPH3pI1xGHoO14OyeTFHIrF2POyOpyvp-u_mCYlKgKwDbpTZPBdPt_8QXD8UnK</recordid><startdate>20200618</startdate><enddate>20200618</enddate><creator>Bosman, S. E. I</creator><creator>Ďurovčíková, D</creator><creator>Davies, F. B</creator><creator>Eilers, A. C</creator><scope>GOX</scope></search><sort><creationdate>20200618</creationdate><title>A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission</title><author>Bosman, S. E. I ; Ďurovčíková, D ; Davies, F. B ; Eilers, A. C</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-arxiv_primary_2006_107443</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2020</creationdate><topic>Physics - Astrophysics of Galaxies</topic><topic>Physics - Cosmology and Nongalactic Astrophysics</topic><toplevel>online_resources</toplevel><creatorcontrib>Bosman, S. E. I</creatorcontrib><creatorcontrib>Ďurovčíková, D</creatorcontrib><creatorcontrib>Davies, F. B</creatorcontrib><creatorcontrib>Eilers, A. C</creatorcontrib><collection>arXiv.org</collection></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext_linktorsrc</fulltext></delivery><addata><au>Bosman, S. E. I</au><au>Ďurovčíková, D</au><au>Davies, F. B</au><au>Eilers, A. C</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission</atitle><date>2020-06-18</date><risdate>2020</risdate><abstract><![CDATA[Reconstruction techniques for intrinsic quasar continua are crucial for the
precision study of Lyman-$\alpha$ (Ly-$\alpha$) and Lyman-$\beta$ (Ly-$\beta$)
transmission at $z>5.0$, where the $\lambda<1215 A$ emission of quasars is
nearly completely absorbed. While the number and quality of spectroscopic
observations has become theoretically sufficient to quantify Ly-$\alpha$
transmission at $5.0<z<6.0$ to better than $1\%$, the biases and uncertainties
arising from predicting the unabsorbed continuum are not known to the same
level. In this paper, we systematically evaluate eight reconstruction
techniques on a unified testing sample of $2.7<z<3.5$ quasars drawn from eBOSS.
The methods include power-law extrapolation, stacking of neighbours, and six
variants of Principal Component Analysis (PCA) using direct projection, fitting
of components, or neural networks to perform weight mapping. We find that
power-law reconstructions and the PCA with fewest components and smallest
training sample display the largest biases in the Ly-$\alpha$ forest
($-9.58\%/+8.22\%$ respectively). Power-law extrapolations have larger scatters
than previously assumed of $+13.1\%/-13.2\%$ over Ly-$\alpha$ and
$+19.9\%/-20.1\%$ over Ly-$\beta$. We present two new PCAs which achieve the
best current accuracies of $9\%$ for Ly-$\alpha$ and $17\%$ for Ly-$\beta$. We
apply the eight techniques after accounting for wavelength-dependent biases and
scatter to a sample $19$ quasars at $z>5.7$ with IR X-Shooter spectroscopy,
obtaining well-characterised measurements for the mean flux transmission at
$4.7<z<6.3$. Our results demonstrate the importance of testing and, when
relevant, training, continuum reconstruction techniques in a systematic way.]]></abstract><doi>10.48550/arxiv.2006.10744</doi><oa>free_for_read</oa></addata></record> |
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| title | A comparison of quasar emission reconstruction techniques for $z\geq5.0$ Lyman-$\alpha$ and Lyman-$\beta$ transmission |
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