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= Click here for instructions on how to join the WEAVE Science Team and g= uidelines for existing Science Team members.
WEAVE (WHT Enhanced Area Velocity E= xplorer) is the next-generation wide-field survey facility for the W= illiam Herschel Telescope (WHT). Expected to start operations in early 2023= , its goals are to complement the major space- and ground-based programmes = in the current and coming decade, including Gaia, LOFAR and Apertif, by pro= viding a dedicated wide-field optical spectroscopic instrument in the North= ern Hemisphere.
Its wide-ranging science goals cover vari= ous fields of Galactic and extragalactic astronomy. There are currently eig= ht independent WEAVE surveys planned, each with their own dedicated Science= Teams, that will use a large fraction of 5 years of WHT time. WEAVE, with = its nearly 1000-fibre MOS mode and IFU modes, will also be accessible to th= e wider astronomical community through open competition outside of this tim= e.
A shor= t overview of each of the planned WEAVE surveys is provided below, starting= from surveys focusing on the nearby Universe and extending towards higher = redshifts.
Click here for = a photo gallery of the Science Team Leads.
The WEAVE Science Case is available to the public here: WEAVE-SCI-002 The WEAVE Science Case v3.2.pdf
The Milky Way (MW) is the only galaxy for= which we can determine a precise chemo-dynamical formation and evolutionar= y history. The Gaia satellite is revolutionising the study of the MW and it= s satellite companions by delivering photometry, 3-D positions, and proper = motions for 1.8 billion stars brighter than G =3D 20.8.
Fully exploiting the Gaia data requires o= btaining accurate radial velocities and elemental abundances for stars that= are too faint for Gaia's Radial Velocity Spectrometer (RVS). For stars wit= h V magnitude fainter than 15-16 (radial velocities) or V fainter than 12 (= elemental abundances), WEAVE's Galactic Archaeology survey will provide exa= ctly such data, enabling the determination of fundamental Galactic paramete= rs (mass, mass assembly over time, etc.), the origin of the thick stellar d= isk, identifying/characterising streams of stars in the Galaxy's halo to un= derstand the fraction of the halo originating in accreted systems, and perf= orming fundamental galaxy-dynamics experiments to understand the r=C3=B4le = of non-axisymmetries in disk substructures.
WEAVE's vantage point from the Northern H= emisphere is crucial for targeting the outer MW disk. The WEAVE Galactic Ar= chaeology survey will be unique; no other existing or proposed optical faci= lity (e.g. LAMOST, DESI, SDSS) will provide such a survey to similar depth = or spectral resolution, while the southern sky inaccessible to WEAVE will b= e covered by ESO's forthcoming 4MOST facility. The Galactic Archaeology sur= vey is divided into sub-surveys targeting the Galactic halo, disk(s) and op= en clusters, using both the low and high-resolution modes of WEAVE (R~5000 = and R~20000, respectively), targeting millions of stars.
The Milky Way's disk is an outstanding lo= cation for studying the physics of the many, poorly understood, short-lived= phases of stellar evolution, from the most massive O stars, through Cephei= ds, to stellar remnants and their ejecta. The SCIP survey will target these= stars along with their environment (i.e. the circumstellar and interstella= r medium) over more than 1200 sq. deg. of the Galactic disk; this will allo= w WEAVE to address questions regarding the relations between star formation= , evolution, and the ISM seen both in emission and absorption. For the youn= gest OBA stars, the SCIP survey will complete the kinematics of stars with = Gaia astrometry. A high-spectral-resolution focus on the Great Cygnus Rift = star-forming region and the Galactic Anticentre will enable targeted studie= s of, respectively, high-mass stars within an important complex, and of Gal= actic structure and dynamics in the Anticentre region.
The Galaxy Clusters survey will focus on = three different science areas. A survey of low-mass cluster galaxies will t= race the evolution of bright dwarf galaxies in X-ray-selected nearby galaxy= clusters up to a redshift of 0.04. In the infall-regime survey, the focus = will be on characterising the transformation of galaxies during their infal= l process towards the cluster centre. For this purpose, a total of 20 galax= y clusters with a range of masses at z~0.05 will be targeted. Lastly, the c= osmological clusters survey will study the evolution of galaxies in cores o= f clusters out to a redshift of 0.5, also placing constraints on cosmologic= al parameters and global scaling relations using a complete sample of Sunya= ev-Zeldovich clusters.
The StePS survey (Iovino et al., 2022, A&A, submitted) w= ill obtain high-quality spectra (typical S/N =E2=88=BC 10=C3=85=E2=88= =921 at R =E2=88=BC 5000) for a magnitude-limited (IAB <= ; 20.5) sample of =E2=88=BC 25,000 galaxies, the majority in the redshift r= ange between= 0.3 and 0.7. The survey goal is to provide precise spectral measurements in the = crucial interval that bridges the gap between LEGA-C and SDSS data. &= nbsp;StePS will use WEAVE to trace back in cosmic time the evolution of gal= axy stellar population properties as a function of galaxy stellar mass, sta= r formation activity and environment, thereby providing much needed empiric= al constraints on the physical mechanisms that regulate galaxy formation an= d assembly history.
Apertif is an innovative focal-plane arra= y system on the Westerbork synthesis radio telescope in Dwingeloo that will= allow wide-field HI surveys out to cosmological distances (z~0.2). With co= mmissioning expected to finish in early 2017, Apertif will provide radio-so= urce targets to WEAVE for optical follow-up of 100,000 massive gas-rich gal= axies in a timely fashion. The WEAVE-Apertif survey will be able to harness= WEAVE's dual integral-field-unit (IFU) capability, as the large IFU will b= e ideally suited for large nearby galaxies, while the multiple small IFUs w= ill be perfect for small and distant galaxies.
The Low Frequency Array (LOFAR) is a new-= generation radio telescope, with unparalleled sensitivity and survey speed = due to its very large instantaneous field of view, a result of its innovati= ve design. The LOFAR Surveys Key Science Project is producing tiered survey= s across the entire northern sky, providing precise positions for WEAVE, wh= ich will be its primary source of redshift information. The WEAVE-LOFAR sur= vey will perform multi-object and resolved optical spectroscopic follow-up = of more than a million low-frequency selected radio sources, enabling a ver= y wide and exciting range of science questions to be addressed. Topics rang= e from measuring the evolving relationship between star formation and accre= tion =E2=80=94 including accounting for the influence of mass and environme= nt =E2=80=94 to identifying radio galaxies deep in the epoch of reionisatio= n.
How did the accelerated expansion of the = universe emerge? How do galaxies regulate gas accretion and hence star form= ation? How is this star formation connected to (circumgalactic) environment= and the (intergalactic) cosmic web context? How do the sources of (re)ioni= sation imprint themselves onto the intergalactic medium? These are some of = the pressing questions motivating the extragalactic astrophysics planned wi= thin the WEAVE-QSOs survey. The primary target of observations will be the = Lyman-alpha forest =E2=80=94 a 'forest' of absorption lines seen along the = line of sight to distant QSOs that are caused by the intervening intergalac= tic medium (IGM) and circumgalactic medium (CGM). The WEAVE-QSOs survey wil= l provide IGM/CGM temperature, density, 3-D mapping and clustering. Cluster= ing information includes the measurement of Baryonic Acoustic Oscillations,= a 'standard ruler' enabling us to probe the accelerating expansion of the = Universe and thus gain a better understanding of 'dark energy'.
What is the star formation history in= the solar neighbourhood? How much mass do stars lose when they evolve off the main sequence? What = ;are the progenitors of type Ia s= upernovae routinely used to map the Universe? And what happens to the many known planetary systems = ;(including our solar system) onc= e their host stars reach the end of hydrogen-core burning? These fundamental questions are all addresse= d by the study of white dwar= fs, the endpoints of stellar evolution for ~95% of all stars. WEAVE-WD will obtain high-quality spectra= of ~60,000 white dwar= fs identified by the ESA Gaia mission, and the analysis of these data will provide accurate masses and = ages from which the local st= ar formation history, the initial mass function, and the initial-to-final mass function will be determi= ned. WEAVE-WD will be the la= rgest sample of spectroscopically confirmed white dwarfs, and <= span style=3D"color: rgb(0,0,0);">provide detailed statistics on the freque= ncy of double-degenerate whi= te dwarfs that will merge within a Hubble time, and on the bulk abundances of tidally disrupted planete= simals.