LAMOST Extragalactic Surveys (LEGAS) Yipeng Jing Shanghai Astronomical Observatory For the LEGAS working group

LAMOST 河外工作组视频会议纪要 2010/07/27 河外工作组件将首先制定北天的观测计划，用于 2011 年上半年的 LAMOST 观测。 南天的观测输入星表将基于 SDSS III 的 2010 年底的 正式释放和 U 波段巡天的结果，在 2011 年上半年制定。 在巡天计划方面，星系和类星体样本保持不变： 星系要求在 1 个半小 时的曝光内达到 r=19.5,S/N=10 ；类星体要求达到 i=20.5,S/N=5 。 EMG ：基于 SDSS III 的进展情况，计划放弃。 对于 ELG ，需要进行 细化巡天的相关参数（如选择判据，极限星等， sampling factor 等）。 对于光谱分辨率，在能够保持上述极限星等的情况下，在 范围内都是可以接受的。 将基于河内工作组提出的 SRS （ Sceience Requuirements Specification ）的基础上， 河外工作组将进一步细化河外巡天的 SRS ，具体由景益鹏和吴宏负责与邓李才沟通和实施。 在 2011 年正式观测前，需要进一步测试望远镜的相关性能。测试天区 和去年河外工作组所提相同， 但对于目标源，可根据科学目标进行适 当的调整（如增加 ELG 等）。 河外工作组计划利用 LAMOST 配套的相关经费招聘从事 LAMOST 河 外巡天工作的博士后（ LAMOST fellowship ）， 工资额度在 万 RMB 之间。

Oct 20, 2007

Structure of LAMOST MB mirror Fiber Positioning Fibers MA mirror Spectrographs CCDs

Main Parameters Main function spectroscopic sky survey Effective aperture 4 meter Focal length 20 meter Angular FOV5  （ linear FOV  1.75-meter ） Image quality 80% energy encircled in 2.0 acrsec Number of optical fiber 4000 Observing sky area -10   +90  24,000 square degrees Spectral resolution nm Survey capability taking spectral resolution 1nm, integration time 1.5 hours, max bj magnitude: 20.5 m at Xinlong Size of fiber 3.30 arcsec （  320  m linear ）

History and current planning reviewed approved Proposal Nov Apr Feasibility Study Jul Aug Preliminary Design Apr.-May 1999 Jun Detailed Design Sep Construction First Light, 3000 spectra at once 2008 Oct Commissioning Start surveys 2011/2010

Task: make a proposal

Contributions to LEGAS proposal Working Group: –Members: Jing Yipeng, Zhou Xu, Chen Xuelei, Wu Hong, Wu Xuebing, Zheng Xianzhong,Shen Shiyin, Wang Junxian, Li Cheng, Fan Xiaohui –LAMOST engineering contacts: Zhang Haotong, Zhang Yanxia, Luo Ali, Chen Jianjun. Wang Tinggui, Chu Yaoquan, Kong Xu, Yang Xiaohu, Zheng Zheng, Zhang Pengjie, Yuan Weimin, Gao Yu, Jun Pan, Zhou Hongyan, Shang Zhaohui, Lu Youjun, XiaXiaoyang, Liu Fengshan, Wang Jianling, Liang Yanchun, Zhang Wei, Fan Zuhui, Zhang Xinmin, Li Hong, Wang Yougang, Wu Fengquan…..(incomplete) 60 staff members + >120 students and postdocs in China are expected to analyze the LEGAS data

Cutting-edge problems for LAMOST (I) The physical properties of dark energy, the neutrino mass, the physical properties of initial density fluctuation in the early Universe etc, which can be addressed with a better determination of large scale structures on scales 100 h−1Mpc; The generic predictions of the cold dark matter model, such as dark matter halos and especially subhalos around galaxies, which can be tested with a bigger sample of groups of galaxies combined with future deep imaging surveys (e.g. Pan-Starrs and LSST) ;

Cutting-edge problems for LAMOST (II) The physical processes of galaxy formation, such as galaxy interaction, galaxy merging, energy feedback etc, which can be addressed with a denser sampling of structures to a fainter luminosity limit in our local Universe; The growth of supermassive black holes and the co-evolution with their host galaxies, which can be addressed with a better sampling of quasars at z=1-3 and a larger sample of low-z AGNs.

Proposed LEGAS Surveys (the most optimistic) Spectroscopic Surveys of galaxies and QSOs in the NGC of 8000 sq degrees (SDSS sky) and in the SGC of about 3500 sq degrees: –LAMOST Galaxy Deep Survey; 2.3 million of r<19.5 in 3400 sq deg; –LAMOST Galaxy Shallow Survey; 2.4 million of r<19.0 in the rest 8100 sq deg ； –LAMOST Early Massive Galaxy (EMG) Survey; 1 million of ideV<20.0 ； –LAMOST Quasar Survey; 0.4 million of i<20.5; A data base of 6 million extragalactic spectra

SRD To r=19 with 0.1 mag in 1.5 hours for galaxies (S/N>10) To i=20.5 (S/N>5) Resolution R>1000 (secondary compared to the depth) >3000 square degrees

Pilot surveys 140 square degrees sky areas at high Galactic latitude –r<19.5 galaxies (800/deg**2) –i<20 EMGs (100/deg**2) –19.1<i<20.5 point sources (2000/deg**2) 40 dark nights 120 regions of rich clusters for early science +calibration in ALL LEGAS region Determine how many transparent nights are available for LEGAS each year?

Another LEGAS proposal The current one: –Competition from SDSS III on EMGs –According to the telescope design parameters A “descoped” one, but still unique and very powerful: –Shallow survey (r<19) in square degrees (3.8 million) –QSO survey (19.1<i<20.5) (0.6 million) –Exposure time: 30 minutes –3.3 years; 90 % complete for galaxies and 100% complete for QSOs; fiber usage rate is 56%

LAMOST Galaxy Deep Survey Spectroscopic survey of galaxies to a magnitude r = 19.5 in selected areas of 3400 square degrees at NGC and SGC; The spectra will be taken with an exposure of 90 min during dark nights; Main Scientific Objectives: –Study galaxy properties (including AGNs) to a low luminosity, as function of local & global environments; –Quantify galaxy evolution from z=0.4 to z=0

LAMOST Galaxy Shallow Survey Spectroscopic Survey of galaxies to a magnitude r = 19.0 in the area (8100 sq deg) other than that of the Deep Survey in NGC and SGC. Taken with exposure time of 30 minutes. Main Scientific Objectives: –Combining with Deep Survey, to construct the structures from small (10 Kpc/h; groups) to very large (200 Mpc/h) scales (including BAO)

LAMOST Early Massive Galaxy (EMG) Survey Spectroscopic Survey of intrinsically bright and massive galaxies to a magnitude ideV = 20. The exposure time is set following Deep and Shallow surveys in the same sky area; Main Scientific Objectives: –Large scale structures and BAOs –Evolution of the massive galaxies from z=0.8 to z=0

LAMOST Quasar Survey Spectroscopic Survey of quasars to a magnitude i = 20.5, with the exposure time set to follow Deep and Shallow surveys in the same sky area. The quasars will be selected using SDSS photometry and the UKIDSS infrared photometry where available. Main Scientific Objectives –Uncover quasars at z=2.5 by SDSS QSO Sep.survey –Uncover dust obscured QSOs and those missed by the SDSS QSO color criteria with the UKIDSS photometry

Main parameters galaxy deep, galaxy shallow, quasar, and early massive galaxies (EMG), –Spectrum resolution R=1000 for all (available right now); 2000 fine, but not fixed. –The signal to noise S/N limit is set to be 15, 10, 15, 5 (in a pixel) for the four subsurveys respectively; –The mean number density of the objects is about 800, 400, 100, 100 per square degrees respectively; –Each subsurvey requires the completeness above 90 percent.

SSS (Survey Strategy Software) simulation (6 years; fiber usage is 55%)

Shen Shiyin provides

Science Case 1. Clustering of galaxies on the largest ever scales Will combine LRGs, QSOs and galaxy samples to explore the clustering of galaxies on large scales (>50 Mpc/h), including BAO. The results will give new constraints on dark energy, inflation theories, Non-Gaussianity, modified gravity, and neutrinos mass;

Simulations of NGC EMGs 距今 42 亿年 距今 67 亿年 赤道两侧 3 度范围内的亮红 星系的分布情况（模拟） SLOAN 2 LAMOST SLOAN 2 Two-point CF Cheng LI

Constraining the EOS of dark energy, e.g.,w(z)=w0+w1 z/(1+z) Wang,X, Chen,X et al. Hong LI et al.

Science Case 2. Delineate filaments and study the environment dependence of galaxies Zhang et al. (2009)

Case 3. Formation of dwarf galaxies Filamentary structures in the Universe are delineated with the dense sampling; Understanding why dwarf galaxies have (or do not have ) formed, compared with LCDM (feedback processes) May constrain the properties of dark matter particles

LAMOST 主星系样本预研究 距今 24 亿年 距今 49 亿年 暗星系样本的两点相关函数暗星系样本的两点相关函数 星系的分布星系的分布 SLOAN LAMOST SLOAN

Mo et al. (2005)

Distribution of dwarf galaxies （ to ALFALFA HI limit ）： CDM vs Warm dark matter （ m ＝ 1kev) ； halo mass about 10**10 M_sun/h Zavala, Jing ， et al 2009, ApJ

Case 4. quantify dark matter distribution with groups Understanding galaxy property and evolution in dense environments Quantifying dark matter distribution within groups; Combining Pan Starrs or LSST, may be feasible to explore subhalos

LAMOST Case 5: Reveal the evolution of galaxies in the last 4 billion years (15 times GAMA) 4 billion years

Case 6: HOD of different galaxies Measuring the clustering and abundance of galaxies with different properties; Obtain Occupation Distribution of different galaxies in dark matter Halos (HOD) Study the evolution of galaxies from the HOD at different redshifts

HOD method: assuming N galaxies in halo of mass M ； First applied to Las Campanas Redshift survey ， getting alpha ＝ 0.09 Jing, Mo, Boerner 1998, ApJ, 494, 1

Idit Zehavi et al., ApJ, 630:1–27, 2005 ; Yang et al 2003 for 2dF Conditional luminosity functions of galaxies inferred from the best-fit HOD parameters for the luminosity-threshold samples, shown at three different halo mass scales 不同质量暗物质晕内部的 星系光度函数

Projected two-point auto-correlation functions and best- fit HODs for the two luminosity-threshold LRG samples. Zheng Zheng,…,JYP, et al., to be published （ a ）亮红星系的投 影两点相关函数； （ b ）不同质量暗物 质晕内部的亮红星系 数目等 （ c ）卫星星系的比 例 （ d ）

Case 7: QSO Luminosity Function and evolution obtain the most accurate quasar luminosity function, and to understand better about the black hole assambly from z = 3 Will probably detect the luminosity dependence of QSO clustering, and be very powerful to study the coevolution of galaxies and central black holes Will be an ideal sample to explore BAO and LSS at z=2, for constraining DE and physics of the Early Universe

Richards,G

Case 8: uncover obscured QSOs Since part of the QSO sample will be based on UKIDSS-SDSS, it is very useful for studying obscured quasars, testing the unified model of AGN and constraining the growth history of super massive black holes;

These cases are only examples!!! The list is not exclusive In SDSS, only half of the discoveries had been anticipated

Final Remarks and next steps SDSS II and 2DF have made great achievements in studying galaxy formation and cosmology. LAMOST, if can reach its design specifications, will definitely make many remarkable achievements in extragalactic astronomy in the post-SDSS(II) era;

Next Steps Manpower and expertise: –60 staff members + >100 postdoc and students, from almost all Chinese astronomical institutes –>30 members have strong science record, either in observations and/or in theoretical simulation modeling –There is no lack of expertise to convert the reduced data to science –Many of them are recent PHD returnees, having good connections with the international community, and are willing to collaborate with overseas experts

Data Reduction and Mask files –Data reduction at the science requirement level will be done by the LAMOST data reduction team, but the working group is willing and necessary to work closely with the data reduction team to understand the various “selection effects” –Make mask files –Test with large mock galaxy samples to understand and improve

More image data needed In the southern galactic cap, more image data in addition to SDSS is needed; in discussion with Pan Starrs;(before that, we use SDSS deg**2) U-band photometry is needed as well; is planned to be obtained by NAOC at the Bob 2.3 m telescope at Kitt Peak of Univ. Arizona (Led by Xu Zhou)

The input sources only include galaxy(r<19) and QSO(i<20.5). There are about 3.8 million galaxies and 0.6 million QSOs, each of them is set with an exposure time 0.5h. It takes about 3 years and 3 months to reach the completeness of 90%. The average fiber usage is 56%. Since the priority of QSO is higher than galaxy, the completeness of QSO is about 100%.

The surveys will be elaborated after the pilot survey data Thank you!