SMU S.A. Y FILIALES ESTADOS FINANCIEROS
SMU S.A. Y FILIALES
2. BASES DE PRESENTACIÓN Y CONSOLIDACIÓN
In the last decade, a huge effort has been spent in the development of wide-field spectroscopic survey facilities, both ground- and space-based, which led to amazing discoveries and made possible the construction of detailed three-dimensional maps of the Universe to probe its large scale structure.
The 2-degree-Field Galaxy Redshift Survey6 [2dFGR;61] (1997-2002) obtained spectra for
about 220,000 objects, mainly galaxies, brighter than a nominal extinction-corrected magni- tude limit of bJ=19.45 by scanning an area of approximately 1500 deg2. The survey provided accurate measurements of the power spectrum of galaxies, allowing precise determinations of the total mass density of the Universe and the baryon fraction [225]. It measured the distortion of the clustering pattern in redshift space, providing independent constraints on the total mass density and the spatial distribution of dark matter [221,130]. It also provided evidence for a non-zero cosmological constant, and constraints on the equation of state of the dark energy [88, 227].
Its successor, the Sloan Digital Sky Survey7 [SDSS 323, 118, 270], has created the most
detailed 3D maps of the Universe ever made so far, with deep multi-color images of one third of the sky, and spectra for more than 3 million astronomical objects. Using the dedicated 2.5-m Sloan telescope [118] at the Apache Point Observatory, New Mexico, it has imaged the sky in five optical photometric bands (u, g, r, i, z) between 3000 and 10,000 Å, with a drift-scanning, mosaic CCD camera [117,106]. During the first stages of the mission, called SDSS-I (2000-2005) and SDSS-II (2005-2008), it obtained spectra and deep, multi-color images of ∼ 930, 000 galaxies and more than 120,000 quasars. In the second phase (2009- 2014), the SDSS-III Baryon Oscillation Spectroscopic Survey [BOSS; 90, 80] targeted 1.5 million galaxies up to z = 0.7 [8] and about 160,000 Lyman-α forest quasars in the redshift
6http://www.2dfgrs.net/ 7http://www.sdss.org/
range 2.2 < z < 3 [268]. BOSS has measured the Baryon Acoustic Oscillation (BAO) feature [91] in the clustering of galaxies and quasars with unprecedented accuracy, probing that the seeds of the large scale structure we see today in the Universe are quantum fluctuations which propagate as sound waves in the very early stages of the Universe. The SDSS high-precision maps of cosmic expansion history using baryon acoustic oscillations have been especially influential in quantifying these results, yielding exquisite constraints on the geometry and energy content of the universe. BAOs were first detected in galaxy clustering by the SDSS-I and in the contemporaneous 2dF Galaxy Redshift Survey, and have since also been detected in intergalactic hydrogen gas using Lyman-α forest techniques. These BAO measurements are complemented by the results of the SDSS-II Supernova Survey8, which has provided the
most precise measurements yet of cosmic expansion rates over the last four billion years. In addition, statistical measurements of galaxy motions and weak gravitational lensing provide some of the strongest evidence to date that Einstein�s General Relativity is an accurate description of gravity on cosmological scales.
Its extension, the ongoing SDSS-IV/extended Baryon Oscillation Spectroscopic Survey (Dawson et al. 2015, in prep.) plans to target about 350,000 Luminous Red Galaxies (LRGs) in the redshift range 0.6 < z < 0.8, 260,000 emission-line galaxies in 0.6 < z < 1 and 740,000 Ly-α forest quasars in 0.9 < z < 3.5. It will precisely measure the expansion history of the Universe throughout 80% of cosmic history, back to when the Universe was less than 3 billion years old, and improve constraints on the nature of dark energy.
The near-future Dark Energy Spectroscopic Instrument9 [DESI; 260] will use the 4-m
Mayall telescope located at Kitt Peak, Arizona, to survey about 14,000 deg2 of the sky to
unveil the dark ages of the Universe. It will measure the expansion of the Universe by observing the imprint of baryon acoustic oscillations set down in the first 380,000 years of its existence. This feature has the same source as the pattern seen in the cosmic microwave
8http://classic.sdss.org/supernova/aboutsupernova.html 9http://desi.lbl.gov/
background, but DESI will map it as a function of cosmic time, while the CMB can see it only at one instant. It is imprinted on all matter at large scales and can be viewed by observing galaxies of various kinds or by observing the distribution of neutral hydrogen (i.e. H II regions, see Sec.1.6) across the cosmos, showing up as excess correlations at the characteristic distance of the sound horizon at decoupling. DESI will collect about 10 million spectra of LRGs up to z = 1, ELGs up to z = 1.7 and Ly-α forest quasars up to z = 3.5. From these will come 3D maps of the distribution of matter covering unprecedented volume. This will help to establish whether cosmic acceleration is due to a mysterious component of the Universe, the dark energy, or a cosmic-scale modification of General Relativity, and will constrain models of primordial inflation. This survey will have a dramatic impact on our understanding of dark energy through its primary measurement, that of baryon acoustic oscillations. In addition to the constraints on dark energy, the galaxy and Ly-α flux power spectra will reflect signatures of neutrino mass, scale dependence of the primordial density fluctuations from inflation, and possible indications of modified gravity. To realize the potential of these techniques requires an enormous number of redshifts over a deep, wide volume and DESI was specifically designed with such requirements.
The 4-meter Multi-Object Spectroscopic Telescope10[4MOST;81] located at Cerro Paranal,
Chile, will use the 4-m VISTA telescope to simultaneously measure spectra of 1 million Ac- tive Galactic Nuclei (AGN) out to z ∼ 5 and [OII] emission-lines up to z = 2, over 4 deg2 of
the sky. It will be able to simultaneously obtain spectra of ∼ 2400 objects distributed over an hexagonal field-of-view of 4 deg2. This high multiplex of 4MOST, combined with its high
spectral resolution, will enable detection of chemical and kinematic substructure in the stel- lar halo, bulge and thin and thick discs of the Milky Way, thus help unravel the origin of our home galaxy. The instrument will also have enough wavelength coverage to secure velocities of extra-galactic objects over a large range in redshift, thus enabling measurements of the evolution of galaxies and the structure of the cosmos. This instrument enables many science
goals, but the design is especially intended to complement three key all-sky, space-based observatories of prime European interest: Gaia11, EUCLID (see below), and eROSITA12.
The Prime Focus Spectrograph [PFS; 289, 269] of the Subaru Measurement of Images and Redshifts (SuMIRe) project is a multi-fiber optical/near-infrared spectrograph that will use the Subaru 8.2-m telescope at Mauna Kea, Hawaii, to simultaneously obtain spectra of 2400 cosmological/astrophysical targets in the wavelength range from 0.38− 1.3 µm, in the attempt to study galactic archaeology and galaxy/AGN evolution. Among its targets, it will collect spectra of emission-line galaxies up to z = 2 [269].
The above ground-based surveys have been complemented by space-based mission in the near-infrared which have provided precise measurements of [OII] and Hα fluxes from emission-line galaxies over a wide range of redshifts. The advantage of observing ELGs from space is that we can get rid of the diffuse thermal emission from the atmosphere. Among these facilities, the WFC3 Infrared Spectroscopic Parallel13 [WISP; 10] survey has collected
Hα spectra [11, 85] using the two infrared grisms (G102 with λ = 0.80− 1.17 µm, and G141
λ = 1.11− 1.67 µm) of the Wide Field Camera 3 of the Hubble Space Telescope14 (HST) in pure parallel mode, but for a very tiny area of the sky.
The near-future EUCLID15 [174,258] mission has been designed with characteristics very
similar to WISP, but much larger field of view. It is a near-IR slitless spectroscopic system with two deep-field instruments, the visual imager (VIS) providing high-quality images to carry out the weak lensing galaxy shear measurement, and the near-IR spectrometer pho- tometer (NISP) to provide photometric redshifts and slitless spectroscopy [174]. EUCLID will scan 15,000 deg2 of the sky using a 1.2-m telescope. The forecast for the spectroscopic
program is 25-50 million galaxies out to z = 2 in one visible riz broad band (550-920nm)
11http://sci.esa.int/gaia/ 12http://www.mpe.mpg.de/eROSITA
13http://wisps.ipac.caltech.edu/Home.html
14https://www.nasa.gov/mission_pages/hubble/main/ 15http://sci.esa.int/euclid/
down to magnitude AB=24.5 [174, 175], and their exact number will be limited by the Hα line flux. This corresponds to a look-back time of about 10 billion years, thus covering the period over which dark energy accelerated the expansion of the Universe. This instrument is optimized for two primary cosmological probes: galaxy weak lensing and baryon acoustic oscillations. With its wide-field capability and high-precision design, EUCLID will inves- tigate the properties of dark energy by accurately measuring both the acceleration as and the variation of the acceleration at different ages of the Universe. It will test the validity of general relativity on cosmic scales, explore the nature and properties of dark matter by mapping the 3D dark matter distribution in the Universe, and contribute to refine the initial conditions at the beginning of our Universe, which seed the formation of the cosmic struc- tures we see today. Euclid will also deliver morphologies, masses and star-formation rates with four times better resolution and 3 NIR magnitudes deeper than possible from ground [174]. It is poised to uncover new physics by challenging all sectors of the cosmological model and can thus be thought of as the low-redshift, 3D analogue and complement to the map of the high-z Universe provided by the Planck16 mission.