LAMOST.vs. Dark matter and Dark energy

大天区面积多目标光纤光谱天文 望远镜 The Large Sky Area Multi- Object Fiber Spectroscopic Telescope (LAMOST)

Location Xinglong Station, National Astronomical Observatories, Chinese Academy of Sciences Cost RMB 235 Million yuan (~$30M) Construction Period 7 years

Project Organization Xinglong Station, NAOC the site Nanjing: NIAOT (NAOC) Telescope Instruments Hefei: USTC Science Beijing: NAOC Project HQ Instruments & Software Science

Basic parameters of LAMOST 4-meter Schmidt telescope The declination of observable sky area ranges from -10  to +90 . 20 square degree of the FOV 4000 fibers Spectrum resolution: VPH (Volume Phase Holographic) Grating R=1000, 2000, 5000, 10000

ApertureField of View N. of Fibers N. of Spectra 2dF (Galaxy) SDSS (Galaxy) LAMOST (Galaxy)

Key Projects Extra-galactic spectroscopic survey — Galaxy and QSO redshift survey Stellar spectroscopic survey — Structure of the Galaxy, and so on. Cross identification of multi-waveband survey.

LAMOST will make possible a wide range of scientific projects a wide-field, multi-object, high-precision instrument on a 4m telescope can concentrate on large-scale (tens to hundreds of thousands of objects) scientific projects which can’t be carried out on 8-m telescopes, or in ‘single object’ mode on 4m telescopes.

Strategies of galaxy redshift survey Magnitude limited (B=20.5) sample Intrinsic faint object with mean z=0.2 Luminous Red Galaxy (LRG) Deep: 0.3 < z < 0.8

Redshift survey of Galaxy Low Resolution spectroscopy: To obtain the spectra of faint celestial objects (Galaxy and AGN) down to 20.5m with 1nm spectral resolution in 1.5 hours exposure. Wavelength range: 370—900 nm Dark night

LOCAL REDSHIFT SURVEY After 2dF and SDSS Make big local leaps in survey size/volume SDSS Collaboration 2002

Redshift distribution of LAMOST galaxies survey

LRG sample Advantage to select LRG Red color → easy to find the candidate Most luminous galaxy → Map large cosmological volume Correlated with cluster → To detect and study the clustering

The SDSS colour selection of LRGs is very efficient, so it could be make an large cosmological volume sample with high completeness and reliability.. Complementing to SDSS LRGs sample up to r < 20.5, to get galaxy redshift sample with 0.38 < z < 0.8. Overlap in redshift space between Galaxy and QSOs

Scientifically, there is a great benefit in having the two new surveys (Galaxy and QSDs) co-extensive since there is now a substantial overlap in redshift space, providing opportunities to compare the clustering and environments of the two classes of object.

QSO survey Combine the high quality digital image data of SDSS (5 colors) with powerful spectroscopic capabilities of LAMOST to conduct a deep wide field spectroscopic suevey for Quasars

Dark matter and Dark Energy 95% of the mass-energy is dark The “Dark Universe” takes at least two Form: Dark Matter Dark Energy

Two simulations of strong lensing by a massive cluster of galaxies: the same amount of mass is more smoothly distributed over the cluster, causing a very different distortion pattern.

Two simulations of strong lensing by a massive cluster of galaxies. dark matter is clumped around individual cluster galaxies (orange), causing a particular distortion of the background galaxies (white and blue).

Combine the high quality image of the lensing galaxy with powerful spectroscopy capabilities of LAMOST to conduct a deep wide-field spectroscopic sample of all these galaxies, it will be very helpful for the test of the distribution of Dark matter

Distribution of Galaxies Luminosity function of galaxies, Galaxy clustering depend the subset of galaxies: color, luminosity, type,… The redshift-space distortion of the large- scale clustering Topology of Large Scale Structure

Astrophysical challenge for the dark energy Since the dark energy will effect on the expansion of the universe, the dark energy affects all observations of astronomical objects at large redshift

Dark energy and Cosmological test Geometrical features of a universe with a cosmological constant Accelerating universe Angular diameter distance Luminosity distance The redshift-angular size and redshift- magnitude relations Galaxy counts

Dark energy has the following defining properties: (1) it emits no light; (2) it has large, negative pressure (3) it is approximately homogeneous (more precisely, does not cluster significantly with matter on scales at least as large as clusters of galaxies). Because its pressure is comparable in magnitude to its energy density, it is more “energy-like” than “matter-like” (matter being characterized by p<<ρ ). Dark energy is qualitatively very difierent from dark matter.

Dark energy and Cosmological test Age of the universe The gravitational lensing rate Dynamics and the mean mass density The baryon mass fraction in clusters of galaxies The cluster mass function Biasing and the development of nonlinear mass density fluctuations The mass autocorrelation function and nonbaryonic matter

The growth of matter density perturbations

Cosmological parameters from SDSS and WMAP

Dark energy measurements m or D L ~z of SNeIaGarnavich et al  ~z of distant sources Lima et al t~z of high-z objectsAlcaniz et al Einstein ring systemFutamase et al Counts of galaxiesNewman et al SZ cluster surveyHaiman et al SNIa + CMBEfstathiou 1999 SNIa + LSSPerlmutter et al SNIa + QSO’s redshiftNakamura et al …

Baryon oscillations provide a standard rod for mapping the evolution of the geometry of the universe with redshift measure the equation of state of the dark energy

Effect of the survey window function

BARYON ACOUSTIC PEAK IN THE LARGE SCALE CORRELATION FUNCTION OF GALAXIES

Galactic Structure and Evolution

It is evident that our own Milky Way galaxy is the only galaxy that we can presently study at sufficiently high spatial (and kinematical) resolution, and at sufficient depth, to address many of the open questions on the physics of galaxy formation

Stellar spectroscopy plays a crucial role in the study of our Galaxy, not only providing a key component of the 6-dimensional phase space of stellar positions and velocities, but also providing much-needed information on the chemical composition of individual stars. Taken together, information on space motion and composition can be used to unravel the formation process of the Galaxy.

Galactic Structure LAMOST will be able to detect and characterise stars in all of the major components of the Galaxy down to a magnitude limit of V~18 at low spectral resolution R=1000 or Middle spectral resolution for bright stars R=

The merger history of the Galaxy To identify streams as spatial overdensities, moving groups, and star groupings with similar metallicities/ages as determined from spectroscopic classifications of stars The number and inferred extent of identified substructures will be used to constrain the total number of mergers and typical sizes of the merged structures.

Dark matter clumpiness in the Milky Way By tracing the structure and kinematics of stars in our own Galaxy, we should be able to identify and characterize any existing structure in the dark matter distribution in our Galaxy

Progress of LAMOST project

Present Status reviewed approved Proposal Nov Apr Feasibility Study Jul Aug Preliminary Design Apr.-May 1999 Jun Detailed Design Sep Construction First Light 2007

LAMOST 倒计时计划 2005 圆顶设计、加工制造、安装 机架大件安装 块 M A 子镜、 3 块 M B 子镜拼接 小焦面板、 256 个光纤定位单元 一台光谱仪和 2 个 CCD 相机 块 M A 子镜、 37 块 M B 子镜 大焦面板、 4000 光纤定位单元 16 台光谱仪、 32 个 CCD 相机

Production of Mb mirrors Mirror blanks: Schott/Germany Polish: LZOS / Russia

Tests for active optics in outdoor Nanjing

Schmidt correction: FWHM~1.98″ Gravity correction: FWHM~3.6″

Test for Multi-fiber positioning 19 fiber positioning units (Univ. of Sci. & Tech. of China)

Focal Plane Fibers 4000 units (USTC) 2006: make 2007: install

Test model for spectrographs Nanjing

Thank you ！