分类： 天文学 >> 天文学 提交时间： 2023-02-19
Elise Darragh-Ford
John F. Wu
Yao-Yuan Mao
Risa H. Wechsler
Marla Geha
Jaime E. Forero-Romero
ChangHoon Hahn
Nitya Kallivayalil
John Moustakas
Ethan O. Nadler
Marta Nowotka
J. E. G. Peek
Erik J. Tollerud
Benjamin Weiner
J. Aguilar
S. Ahlen
D. Brooks
A. P. Cooper
A. de la Macorra
A. Dey
摘要： We introduce the DESI LOW-Z Secondary Target Survey, which combines the wide
area capabilities of the Dark Energy Spectroscopic Instrument (DESI) with an
efficient, low-redshift target selection method. Our selection consists of a
set of color and surface brightness cuts, combined with modern machine learning
methods, to optimally target low-redshift dwarf galaxies (z 95% complete in target
selection at z < 0.03 between 19
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ting-Wen Lan
R. Tojeiro
E. Armengaud
J. Xavier Prochaska
T. M. Davis
David M. Alexander
A. Raichoor
Rongpu Zhou
Christophe Yeche
C. Balland
S. BenZvi
A. Berti
R. Canning
A. Carr
H. Chittenden
S. Cole
M. -C. Cousinou
K. Dawson
Biprateep Dey
K. Douglass
摘要： The Dark Energy Spectroscopic Instrument (DESI) Survey has obtained a set of spectroscopic measurements of galaxies to validate the final survey design and target selections. To assist in these tasks, we visually inspect (VI) DESI spectra of approximately 2,500 bright galaxies, 3,500 luminous red galaxies (LRGs), and 10,000 emission line galaxies (ELGs), to obtain robust redshift identifications. We then utilize the VI redshift information to characterize the performance of the DESI operation. Based on the VI catalogs, our results show that the final survey design yields samples of bright galaxies, LRGs, and ELGs with purity greater than $99\%$. Moreover, we demonstrate that the precision of the redshift measurements is approximately 10 km/s for bright galaxies and ELGs and approximately 40 km/s for LRGs. The average redshift accuracy is within 10 km/s for the three types of galaxies. The VI process also helps improve the quality of the DESI data by identifying spurious spectral features introduced by the pipeline. Finally, we show examples of unexpected real astronomical objects, such as Ly$\alpha$ emitters and strong lensing candidates, identified by VI. These results demonstrate the importance and utility of visually inspecting data from incoming and upcoming surveys, especially during their early operation phases.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
David M. Alexander
Tamara M. Davis
E. Chaussidon
V. A. Fawcett
Alma X. Gonzalez-Morales
Ting-Wen Lan
Christophe Yeche
S. Ahlen
J. N. Aguilar
E. Armengaud
S. Bailey
D. Brooks
Z. Cai
R. Canning
A. Carr
S. Chabanier
Marie-Claude Cousinou
K. Dawson
A. de la Macorra
A. Dey
摘要： A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (~70%) of the main-survey targets are spectroscopically confirmed as quasars, with ~16% galaxies, ~6% stars, and ~8% low-quality spectra lacking reliable features. A non-negligible fraction of the quasars are misidentified by the standard spectroscopic pipeline but we show that the majority can be recovered using post-pipeline "afterburner" quasar-identification approaches. We combine these "afterburners" with our standard pipeline to create a modified pipeline to improve the overall quasar yield. At the depth of the main DESI survey both pipelines achieve a good-redshift purity (reliable redshifts measured within 3000 km/s) of ~99%; however, the modified pipeline recovers ~94% of the visually inspected quasars, as compared to ~86% from the standard pipeline. We demonstrate that both pipelines achieve an median redshift precision and accuracy of ~100 km/s and ~70 km/s, respectively. We constructed composite spectra to investigate why some quasars are missed by the standard spectroscopic pipeline and find that they are more host-galaxy dominated (i.e., distant analogs of "Seyfert galaxies") and/or dust reddened than the standard-pipeline quasars. We also show example spectra to demonstrate the overall diversity of the DESI quasar sample and provide strong-lensing candidates where two targets contribute to a single spectrum.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. Guy
S. Bailey
A. Kremin
Shadab Alam
D. M. Alexander
C. Allende Prieto
S. BenZvi
A. S. Bolton
D. Brooks
E. Chaussidon
A. P. Cooper
K. Dawson
A. de la Macorra
A. Dey
Biprateep Dey
G. Dhungana
D. J. Eisenstein
A. Font-Ribera
J. E. Forero-Romero
E. Gaztañaga
摘要： We describe the spectroscopic data processing pipeline of the Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey of about 40 million galaxies and quasars using a purpose-built instrument on the 4-m Mayall Telescope at Kitt Peak National Observatory. The main goal of DESI is to measure with unprecedented precision the expansion history of the Universe with the Baryon Acoustic Oscillation technique and the growth rate of structure with Redshift Space Distortions. Ten spectrographs with three cameras each disperse the light from 5000 fibers onto 30 CCDs, covering the near UV to near infrared (3600 to 9800 Angstrom) with a spectral resolution ranging from 2000 to 5000. The DESI data pipeline generates wavelength- and flux-calibrated spectra of all the targets, along with spectroscopic classifications and redshift measurements. Fully processed data from each night are typically available to the DESI collaboration the following morning. We give details about the pipeline's algorithms, and provide performance results on the stability of the optics, the quality of the sky background subtraction, and the precision and accuracy of the instrumental calibration. This pipeline has been used to process the DESI Survey Validation data set, and has exceeded the project's requirements for redshift performance, with high efficiency and a purity greater than 99 percent for all target classes.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Rongpu Zhou
Biprateep Dey
Jeffrey A. Newman
Daniel J. Eisenstein
K. Dawson
S. Bailey
A. Berti
J. Guy
Ting-Wen Lan
H. Zou
J. Aguilar
S. Ahlen
Shadab Alam
D. Brooks
A. de la Macorra
A. Dey
G. Dhungana
K. Fanning
A. Font-Ribera
S. Gontcho A Gontcho
摘要： The Dark Energy Spectroscopic Instrument (DESI) is carrying out a 5-year
survey that aims to measure the redshifts of tens of millions of galaxies and
quasars, including 8 million luminous red galaxies (LRGs) in the redshift range
of $0.4
分类： 天文学 >> 天文学 提交时间： 2023-02-19
DES Collaboration
T. M. C. Abbott
M. Aguena
A. Alarcon
O. Alves
A. Amon
J. Annis
S. Avila
D. Bacon
E. Baxter
K. Bechtol
M. R. Becker
G. M. Bernstein
S. Birrer
J. Blazek
S. Bocquet
A. Brandao-Souza
S. L. Bridle
D. Brooks
D. L. Burke
摘要： We constrain extensions to the $\Lambda$CDM model using measurements from the Dark Energy Survey's first three years of observations and external data. The DES data are the two-point correlation functions of weak gravitational lensing, galaxy clustering, and their cross-correlation. We use simulated data and blind analyses of real data to validate the robustness of our results. In many cases, constraining power is limited by the absence of nonlinear predictions that are reliable at our required precision. The models are: dark energy with a time-dependent equation of state, non-zero spatial curvature, sterile neutrinos, modifications of gravitational physics, and a binned $\sigma_8(z)$ model which serves as a probe of structure growth. For the time-varying dark energy equation of state evaluated at the pivot redshift we find $(w_{\rm p}, w_a)= (-0.99^{+0.28}_{-0.17},-0.9\pm 1.2)$ at 68% confidence with $z_{\rm p}=0.24$ from the DES measurements alone, and $(w_{\rm p}, w_a)= (-1.03^{+0.04}_{-0.03},-0.4^{+0.4}_{-0.3})$ with $z_{\rm p}=0.21$ for the combination of all data considered. Curvature constraints of $\Omega_k=0.0009\pm 0.0017$ and effective relativistic species $N_{\rm eff}=3.10^{+0.15}_{-0.16}$ are dominated by external data. For massive sterile neutrinos, we improve the upper bound on the mass $m_{\rm eff}$ by a factor of three compared to previous analyses, giving 95% limits of $(\Delta N_{\rm eff},m_{\rm eff})\leq (0.28, 0.20\, {\rm eV})$. We also constrain changes to the lensing and Poisson equations controlled by functions $\Sigma(k,z) = \Sigma_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}$ and $\mu(k,z)=\mu_0 \Omega_{\Lambda}(z)/\Omega_{\Lambda,0}$ respectively to $\Sigma_0=0.6^{+0.4}_{-0.5}$ from DES alone and $(\Sigma_0,\mu_0)=(0.04\pm 0.05,0.08^{+0.21}_{-0.19})$ for the combination of all data. Overall, we find no significant evidence for physics beyond $\Lambda$CDM.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
J. Adamek
R. E. Angulo
C. Arnold
M. Baldi
M. Biagetti
B. Bose
C. Carbone
T. Castro
J. Dakin
K. Dolag
W. Elbers
C. Fidler
C. Giocoli
S. Hannestad
F. Hassani
C. Hernández-Aguayo
K. Koyama
B. Li
R. Mauland
P. Monaco
摘要： The measurement of the absolute neutrino mass scale from cosmological large-scale clustering data is one of the key science goals of the Euclid mission. Such a measurement relies on precise modelling of the impact of neutrinos on structure formation, which can be studied with $N$-body simulations. Here we present the results from a major code comparison effort to establish the maturity and reliability of numerical methods for treating massive neutrinos. The comparison includes eleven full $N$-body implementations (not all of them independent), two $N$-body schemes with approximate time integration, and four additional codes that directly predict or emulate the matter power spectrum. Using a common set of initial data we quantify the relative agreement on the nonlinear power spectrum of cold dark matter and baryons and, for the $N$-body codes, also the relative agreement on the bispectrum, halo mass function, and halo bias. We find that the different numerical implementations produce fully consistent results. We can therefore be confident that we can model the impact of massive neutrinos at the sub-percent level in the most common summary statistics. We also provide a code validation pipeline for future reference.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Euclid Collaboration
A. Fumagalli
A. Saro
S. Borgani
T. Castro
M. Costanzi
P. Monaco
E. Munari
E. Sefusatti
N. Aghanim
N. Auricchio
M. Baldi
C. Bodendorf
D. Bonino
E. Branchini
M. Brescia
J. Brinchmann
S. Camera
V. Capobianco
C. Carbone
摘要： Aims. We validate a semi-analytical model for the covariance of real-space 2-point correlation function of galaxy clusters. Methods. Using 1000 PINOCCHIO light cones mimicking the expected Euclid sample of galaxy clusters, we calibrate a simple model to accurately describe the clustering covariance. Then, we use such a model to quantify the likelihood analysis response to variations of the covariance, and investigate the impact of a cosmology-dependent matrix at the level of statistics expected for the Euclid survey of galaxy clusters. Results. We find that a Gaussian model with Poissonian shot-noise does not correctly predict the covariance of the 2-point correlation function of galaxy clusters. By introducing few additional parameters fitted from simulations, the proposed model reproduces the numerical covariance with 10 per cent accuracy, with differences of about 5 per cent on the figure of merit of the cosmological parameters $\Omega_{\rm m}$ and $\sigma_8$. Also, we find that the cosmology-dependence of the covariance adds valuable information that is not contained in the mean value, significantly improving the constraining power of cluster clustering. Finally, we find that the cosmological figure of merit can be further improved by taking mass binning into account. Our results have significant implications for the derivation of cosmological constraints from the 2-point clustering statistics of the Euclid survey of galaxy clusters.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
S. Contarini
G. Verza
A. Pisani
N. Hamaus
M. Sahlén
C. Carbone
S. Dusini
F. Marulli
L. Moscardini
A. Renzi
C. Sirignano
L. Stanco
M. Aubert
M. Bonici
G. Castignani
H. M. Courtois
S. Escoffier
D. Guinet
A. Kovacs
G. Lavaux
摘要： The Euclid mission $-$ with its spectroscopic galaxy survey covering a sky
area over $15\,000 \ \mathrm{deg}^2$ in the redshift range $0.9
分类： 天文学 >> 天文学 提交时间： 2023-02-19
M. Bonici
C. Carbone
S. Davini
P. Vielzeuf
L. Paganin
V. Cardone
N. Hamaus
A. Pisani
A. J. Hawken
A. Kovacs
S. Nadathur
S. Contarini
G. Verza
I. Tutusaus
F. Marulli
L. Moscardini
M. Aubert
C. Giocoli
A. Pourtsidou
S. Camera
摘要： The Euclid space telescope will survey a large dataset of cosmic voids traced by dense samples of galaxies. In this work we estimate its expected performance when exploiting angular photometric void clustering, galaxy weak lensing and their cross-correlation. To this aim, we implement a Fisher matrix approach tailored for voids from the Euclid photometric dataset and present the first forecasts on cosmological parameters that include the void-lensing correlation. We examine two different probe settings, pessimistic and optimistic, both for void clustering and galaxy lensing. We carry out forecast analyses in four model cosmologies, accounting for a varying total neutrino mass, $M_\nu$, and a dynamical dark energy (DE) equation of state, $w(z)$, described by the CPL parametrisation. We find that void clustering constraints on $h$ and $\Omega_b$ are competitive with galaxy lensing alone, while errors on $n_s$ decrease thanks to the orthogonality of the two probes in the 2D-projected parameter space. We also note that, as a whole, the inclusion of the void-lensing cross-correlation signal improves parameter constraints by $10-15\%$, and enhances the joint void clustering and galaxy lensing Figure of Merit (FoM) by $10\%$ and $25\%$, in the pessimistic and optimistic scenarios, respectively. Finally, when further combining with the spectroscopic galaxy clustering, assumed as an independent probe, we find that, in the most competitive case, the FoM increases by a factor of 4 with respect to the combination of weak lensing and spectroscopic galaxy clustering taken as independent probes. The forecasts presented in this work show that photometric void-clustering and its cross-correlation with galaxy lensing deserve to be exploited in the data analysis of the Euclid galaxy survey and promise to improve its constraining power, especially on $h$, $\Omega_b$, the neutrino mass, and the DE evolution.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
K. Naidoo
H. Johnston
B. Joachimi
J. L. van den Busch
H. Hildebrandt
O. Ilbert
O. Lahav
N. Aghanim
B. Altieri
A. Amara
M. Baldi
R. Bender
C. Bodendorf
E. Branchini
M. Brescia
J. Brinchmann
S. Camera
V. Capobianco
C. Carbone
J. Carretero
摘要： Cosmological constraints from key probes of the Euclid imaging survey rely critically on the accurate determination of the true redshift distributions, $n(z)$, of tomographic redshift bins. We determine whether the mean redshift, $$, of ten Euclid tomographic redshift bins can be calibrated to the Euclid target uncertainties of $\sigma()$ is measured in each tomographic redshift bin to an accuracy of order 0.01 or better. By measuring the clustering redshifts on subsets of the full Flagship area, we construct scaling relations that allow us to extrapolate the method performance to larger sky areas than are currently available in the mock. For the full expected Euclid, BOSS, and DESI overlap region of approximately 6000 deg$^{2}$, the uncertainties attainable by clustering redshifts exceeds the Euclid requirement by at least a factor of three for both $n(z)$ models considered, although systematic biases limit the accuracy. Clustering redshifts are an extremely effective method for redshift calibration for Euclid if the sources of systematic biases can be determined and removed, or calibrated-out with sufficiently realistic simulations. We outline possible future work, in particular an extension to higher redshifts with quasar reference samples.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
S. Radinović
S. Nadathur
H. -A. Winther
W. J. Percival
A. Woodfinden
E. Massara
E. Paillas
S. Contarini
N. Hamaus
A. Kovacs
A. Pisani
G. Verza
M. Aubert
A. Amara
N. Auricchio
M. Baldi
D. Bonino
E. Branchini
M. Brescia
S. Camera
摘要： We investigate the cosmological constraints that can be expected from measurement of the cross-correlation of galaxies with cosmic voids identified in the Euclid spectroscopic survey, which will include spectroscopic information for tens of millions of galaxies over $15\,000$ deg$^2$ of the sky in the redshift range $0.9\leq z<1.8$. We do this using simulated measurements obtained from the Flagship mock catalogue, the official Euclid mock that closely matches the expected properties of the spectroscopic data set. To mitigate anisotropic selection-bias effects, we use a velocity field reconstruction method to remove large-scale redshift-space distortions from the galaxy field before void-finding. This allows us to accurately model contributions to the observed anisotropy of the cross-correlation function arising from galaxy velocities around voids as well as from the Alcock-Paczynski effect, and we study the dependence of constraints on the efficiency of reconstruction. We find that Euclid voids will be able to constrain the ratio of the transverse comoving distance $D_{\rm M}$ and Hubble distance $D_{\rm H}$ to a relative precision of about $0.3\%$, and the growth rate $f\sigma_8$ to a precision of between $5\%$ and $8\%$ in each of four redshift bins covering the full redshift range. In the standard cosmological model, this translates to a statistical uncertainty $\Delta\Omega_\mathrm{m}=\pm0.0028$ on the matter density parameter from voids, better than can be achieved from either Euclid galaxy clustering and weak lensing individually. We also find that voids alone can measure the dark energy equation of state to $6\%$ precision.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Euclid Collaboration
L. Gabarra
C. Mancini
L. Rodriguez Munoz
G. Rodighiero
C. Sirignano
M. Scodeggio
M. Talia
S. Dusini
W. Gillard
B. R. Granett
E. Maiorano
M. Moresco
L. Paganin
E. Palazzi
L. Pozzetti
A. Renzi
E. Rossetti
D. Vergani
V. Allevato
摘要： This work focuses on the pilot run of a simulation campaign aimed at investigating the spectroscopic capabilities of the Euclid Near-Infrared Spectrometer and Photometer (NISP), in terms of continuum and emission line detection in the context of galaxy evolutionary studies. To this purpose we constructed, emulated, and analysed the spectra of 4992 star-forming galaxies at $0.3 \leq z \leq 2.5$ using the NISP pixel-level simulator. We built the spectral library starting from public multi-wavelength galaxy catalogues, with value-added information on spectral energy distribution (SED) fitting results, and from Bruzual and Charlot (2003) stellar population templates. Rest-frame optical and near-IR nebular emission lines were included using empirical and theoretical relations. We inferred the 3.5$\sigma$ NISP red grism spectroscopic detection limit of the continuum measured in the $H$ band for star-forming galaxies with a median disk half-light radius of \ang{;;0.4} at magnitude $H= 19.5\pm0.2\,$AB$\,$mag for the Euclid Wide Survey and at $H = 20.8\pm0.6\,$AB$\,$mag for the Euclid Deep Survey. We found a very good agreement with the red grism emission line detection limit requirement for the Wide and Deep surveys. We characterised the effect of the galaxy shape on the detection capability of the red grism and highlighted the degradation of the quality of the extracted spectra as the disk size increases. In particular, we found that the extracted emission line signal to noise ratio (SNR) drops by $\sim\,$45$\%$ when the disk size ranges from \ang{;;0.25} to \ang{;;1}. These trends lead to a correlation between the emission line SNR and the stellar mass of the galaxy and we demonstrate the effect in a stacking analysis unveiling emission lines otherwise too faint to detect.
点击量
待评议
点击量
下载量
评论
