New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data
We present the Ly α Continuum Analysis Network (LyCAN), a convolutional neural network that predicts the unabsorbed quasar continuum within the rest-frame wavelength range of 1040–1600 Å based on the red side of the Ly α emission line (1216–1600 Å). We developed synthetic spectra based on a Gaussian...
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| author | Wynne Turner Paul Martini Naim Göksel Karaçaylı J. Aguilar S. Ahlen D. Brooks T. Claybaugh A. de la Macorra A. Dey P. Doel K. Fanning J . E. Forero-Romero S. Gontcho A Gontcho A. X. Gonzalez-Morales G. Gutierrez J. Guy H. K. Herrera-Alcantar K. Honscheid S. Juneau T. Kisner A. Kremin A. Lambert M. Landriau L. Le Guillou A. Meisner R. Miquel J. Moustakas E. Mueller A. Muñoz-Gutiérrez A. D. Myers J. Nie G. Niz C. Poppett F. Prada M. Rezaie G. Rossi E. Sanchez E. F. Schlafly D. Schlegel Michael F. Schubnell H. Seo D. Sprayberry G. Tarlé B. A. Weaver H. Zou |
| author_facet | Wynne Turner Paul Martini Naim Göksel Karaçaylı J. Aguilar S. Ahlen D. Brooks T. Claybaugh A. de la Macorra A. Dey P. Doel K. Fanning J . E. Forero-Romero S. Gontcho A Gontcho A. X. Gonzalez-Morales G. Gutierrez J. Guy H. K. Herrera-Alcantar K. Honscheid S. Juneau T. Kisner A. Kremin A. Lambert M. Landriau L. Le Guillou A. Meisner R. Miquel J. Moustakas E. Mueller A. Muñoz-Gutiérrez A. D. Myers J. Nie G. Niz C. Poppett F. Prada M. Rezaie G. Rossi E. Sanchez E. F. Schlafly D. Schlegel Michael F. Schubnell H. Seo D. Sprayberry G. Tarlé B. A. Weaver H. Zou |
| author_sort | Wynne Turner |
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| description | We present the Ly α Continuum Analysis Network (LyCAN), a convolutional neural network that predicts the unabsorbed quasar continuum within the rest-frame wavelength range of 1040–1600 Å based on the red side of the Ly α emission line (1216–1600 Å). We developed synthetic spectra based on a Gaussian mixture model representation of nonnegative matrix factorization (NMF) coefficients. These coefficients were derived from high-resolution, low-redshift ( z < 0.2) Hubble Space Telescope/Cosmic Origins Spectrograph (COS) quasar spectra. We supplemented this COS-based synthetic sample with an equal number of DESI Year 5 mock spectra. LyCAN performs extremely well on testing sets, achieving a median error in the forest region of 1.5% on the DESI mock sample, 2.0% on the COS-based synthetic sample, and 4.1% on the original COS spectra. LyCAN outperforms principal component analysis (PCA) and NMF-based prediction methods using the same training set by 40% or more. We predict the intrinsic continua of 83,635 DESI Year 1 spectra in the redshift range of 2.1 ≤ z ≤ 4.2 and perform an absolute measurement of the evolution of the effective optical depth. This is the largest sample employed to measure the optical depth evolution to date. We fit a power law of the form $\tau {(z)={\tau }_{0}(1+z)}^{\gamma }$ to our measurements and find τ _0 = (2.46 ± 0.14) × 10 ^−3 and γ = 3.62 ± 0.04. Our results show particular agreement with high-resolution, ground-based observations around z = 2, indicating that LyCAN is able to predict the quasar continuum in the forest region with only spectral information outside the forest. |
| format | Article |
| id | doaj-art-6a5d26c52e2d4015ac387400d9e08a14 |
| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj-art-6a5d26c52e2d4015ac387400d9e08a142024-11-19T06:16:31ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01976114310.3847/1538-4357/ad8239New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 DataWynne Turner0https://orcid.org/0009-0008-3418-5599Paul Martini1https://orcid.org/0000-0002-0194-4017Naim Göksel Karaçaylı2https://orcid.org/0000-0001-7336-8912J. Aguilar3S. Ahlen4https://orcid.org/0000-0001-6098-7247D. Brooks5https://orcid.org/0000-0002-8458-5047T. Claybaugh6A. de la Macorra7https://orcid.org/0000-0002-1769-1640A. Dey8https://orcid.org/0000-0002-4928-4003P. Doel9K. Fanning10https://orcid.org/0000-0003-2371-3356J . E. Forero-Romero11https://orcid.org/0000-0002-2890-3725S. Gontcho A Gontcho12https://orcid.org/0000-0003-3142-233XA. X. Gonzalez-Morales13https://orcid.org/0000-0003-4089-6924G. Gutierrez14J. Guy15https://orcid.org/0000-0001-9822-6793H. K. Herrera-Alcantar16https://orcid.org/0000-0002-9136-9609K. Honscheid17S. Juneau18https://orcid.org/0000-0002-0000-2394T. Kisner19https://orcid.org/0000-0003-3510-7134A. Kremin20https://orcid.org/0000-0001-6356-7424A. Lambert21M. Landriau22https://orcid.org/0000-0003-1838-8528L. Le Guillou23https://orcid.org/0000-0001-7178-8868A. Meisner24https://orcid.org/0000-0002-1125-7384R. Miquel25https://orcid.org/0000-0002-6610-4836J. Moustakas26https://orcid.org/0000-0002-2733-4559E. Mueller27A. Muñoz-Gutiérrez28A. D. Myers29J. Nie30https://orcid.org/0000-0001-6590-8122G. Niz31https://orcid.org/0000-0002-1544-8946C. Poppett32https://orcid.org/0000-0003-0512-5489F. Prada33https://orcid.org/0000-0001-7145-8674M. Rezaie34https://orcid.org/0000-0001-5589-7116G. Rossi35E. Sanchez36https://orcid.org/0000-0002-9646-8198E. F. Schlafly37https://orcid.org/0000-0002-3569-7421D. Schlegel38https://orcid.org/0000-0002-5042-5088Michael F. Schubnell39H. Seo40https://orcid.org/0000-0002-6588-3508D. Sprayberry41https://orcid.org/0000-0001-7583-6441G. Tarlé42https://orcid.org/0000-0003-1704-0781B. A. Weaver43H. Zou44https://orcid.org/0000-0002-6684-3997Department of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; turner.1839@osu.edu; Center for Cosmology & AstroParticle Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USADepartment of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; turner.1839@osu.edu; Center for Cosmology & AstroParticle Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USA; Department of Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USADepartment of Astronomy, The Ohio State University , 140 West 18th Avenue, Columbus, OH 43210, USA ; turner.1839@osu.edu; Center for Cosmology & AstroParticle Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USA; Department of Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USAPhysics Department, Boston University , 590 Commonwealth Avenue, Boston, MA 02215, USADepartment of Physics & Astronomy, University College London , Gower Street, London, WC1E 6BT, UKLawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USAInstituto de Física, Universidad Nacional Autónoma de México , Ciudad de México C.P. 04510, MexicoNSF NOIRLab , 950 North Cherry Ave., Tucson, AZ 85719, USADepartment of Physics & Astronomy, University College London , Gower Street, London, WC1E 6BT, UKKavli Institute for Particle Astrophysics and Cosmology, Stanford University , Menlo Park, CA 94305, USA; SLAC National Accelerator Laboratory , Menlo Park, CA 94305, USADepartamento de Física, Universidad de los Andes , Carrera 1 No. 18A-10, Edificio Ip, CP 111711, Bogotá, Colombia; Observatorio Astronómico, Universidad de los Andes , Carrera 1 No. 18A-10, Edificio H, CP 111711 Bogotá, ColombiaLawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USAConsejo Nacional de Ciencia y Tecnología , Avenida Insurgentes Sur 1582. Colonia Crédito Constructor, Del. Benito Juárez C.P. 03940, México D.F. Mexico; Departamento de Física, Universidad de Guanajuato—DCI , C.P. 37150, Leon, Guanajuato, MexicoFermi National Accelerator Laboratory , PO Box 500, Batavia, IL 60510, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USADepartamento de Física, Universidad de Guanajuato—DCI , C.P. 37150, Leon, Guanajuato, MexicoCenter for Cosmology & AstroParticle Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USA; Department of Physics, The Ohio State University , 191 West Woodruff Avenue, Columbus, OH 43210, USANSF NOIRLab , 950 North Cherry Ave., Tucson, AZ 85719, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USASorbonne Université , CNRS/IN2P3, Laboratoire de Physique Nucléaire et de Hautes Energies (LPNHE), FR-75005 Paris, FranceNSF NOIRLab , 950 North Cherry Ave., Tucson, AZ 85719, USAInstitució Catalana de Recerca i Estudis Avançats , Passeig de Lluís Companys, 23, 08010 Barcelona, Spain; Institut de Física d’Altes Energies (IFAE), The Barcelona Institute of Science and Technology , Campus UAB, 08193 Bellaterra Barcelona, SpainDepartment of Physics and Astronomy, Siena College , 515 Loudon Road, Loudonville, NY 12211, USADepartment of Physics and Astronomy, University of Sussex , Brighton BN1 9QH, UKInstituto de Física, Universidad Nacional Autónoma de México , Ciudad de México C.P. 04510, MexicoDepartment of Physics & Astronomy, University of Wyoming , 1000 East University, Department 3905, Laramie, WY 82071, USANational Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Chaoyang District, Beijing, 100012, People's Republic of ChinaDepartamento de Física, Universidad de Guanajuato—DCI , C.P. 37150, Leon, Guanajuato, Mexico; Instituto Avanzado de Cosmología A. C. , San Marcos 11—Atenas 202. Magdalena Contreras, 10720. Ciudad de México, MexicoLawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USA; Space Sciences Laboratory, University of California , Berkeley, 7 Gauss Way, Berkeley, CA 94720, USAInstituto de Astrofísica de Andalucía (CSIC) , Glorieta de la Astronomía, s/n, E-18008 Granada, SpainDepartment of Physics, Kansas State University , 116 Cardwell Hall, Manhattan, KS 66506, USADepartment of Physics and Astronomy, Sejong University , Seoul, 143-747, Republic of KoreaCIEMAT , Avenida Complutense 40, E-28040 Madrid, SpainSpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USALawrence Berkeley National Laboratory , 1 Cyclotron Road, Berkeley, CA 94720, USADepartment of Physics, University of Michigan , Ann Arbor, MI 48109, USADepartment of Physics & Astronomy, Ohio University , Athens, OH 45701, USANSF NOIRLab , 950 North Cherry Ave., Tucson, AZ 85719, USADepartment of Physics, University of Michigan , Ann Arbor, MI 48109, USANSF NOIRLab , 950 North Cherry Ave., Tucson, AZ 85719, USANational Astronomical Observatories, Chinese Academy of Sciences , A20 Datun Road, Chaoyang District, Beijing, 100012, People's Republic of ChinaWe present the Ly α Continuum Analysis Network (LyCAN), a convolutional neural network that predicts the unabsorbed quasar continuum within the rest-frame wavelength range of 1040–1600 Å based on the red side of the Ly α emission line (1216–1600 Å). We developed synthetic spectra based on a Gaussian mixture model representation of nonnegative matrix factorization (NMF) coefficients. These coefficients were derived from high-resolution, low-redshift ( z < 0.2) Hubble Space Telescope/Cosmic Origins Spectrograph (COS) quasar spectra. We supplemented this COS-based synthetic sample with an equal number of DESI Year 5 mock spectra. LyCAN performs extremely well on testing sets, achieving a median error in the forest region of 1.5% on the DESI mock sample, 2.0% on the COS-based synthetic sample, and 4.1% on the original COS spectra. LyCAN outperforms principal component analysis (PCA) and NMF-based prediction methods using the same training set by 40% or more. We predict the intrinsic continua of 83,635 DESI Year 1 spectra in the redshift range of 2.1 ≤ z ≤ 4.2 and perform an absolute measurement of the evolution of the effective optical depth. This is the largest sample employed to measure the optical depth evolution to date. We fit a power law of the form $\tau {(z)={\tau }_{0}(1+z)}^{\gamma }$ to our measurements and find τ _0 = (2.46 ± 0.14) × 10 ^−3 and γ = 3.62 ± 0.04. Our results show particular agreement with high-resolution, ground-based observations around z = 2, indicating that LyCAN is able to predict the quasar continuum in the forest region with only spectral information outside the forest.https://doi.org/10.3847/1538-4357/ad8239Convolutional neural networksCosmologyDark energyIntergalactic mediumLarge-scale structure of the universeLyman alpha forest |
| spellingShingle | Wynne Turner Paul Martini Naim Göksel Karaçaylı J. Aguilar S. Ahlen D. Brooks T. Claybaugh A. de la Macorra A. Dey P. Doel K. Fanning J . E. Forero-Romero S. Gontcho A Gontcho A. X. Gonzalez-Morales G. Gutierrez J. Guy H. K. Herrera-Alcantar K. Honscheid S. Juneau T. Kisner A. Kremin A. Lambert M. Landriau L. Le Guillou A. Meisner R. Miquel J. Moustakas E. Mueller A. Muñoz-Gutiérrez A. D. Myers J. Nie G. Niz C. Poppett F. Prada M. Rezaie G. Rossi E. Sanchez E. F. Schlafly D. Schlegel Michael F. Schubnell H. Seo D. Sprayberry G. Tarlé B. A. Weaver H. Zou New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data The Astrophysical Journal Convolutional neural networks Cosmology Dark energy Intergalactic medium Large-scale structure of the universe Lyman alpha forest |
| title | New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data |
| title_full | New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data |
| title_fullStr | New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data |
| title_full_unstemmed | New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data |
| title_short | New Measurements of the Lyα Forest Continuum and Effective Optical Depth with LyCAN and DESI Y1 Data |
| title_sort | new measurements of the lyα forest continuum and effective optical depth with lycan and desi y1 data |
| topic | Convolutional neural networks Cosmology Dark energy Intergalactic medium Large-scale structure of the universe Lyman alpha forest |
| url | https://doi.org/10.3847/1538-4357/ad8239 |
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