Un universo tridimensional con Gaia

Francesca FiguerasOn behalf of the UB- Gaia team

Universidad de Barcelona (Spain)

Index

• Basic principles and data reduction strategy • What Gaia will observe: the Gaia Simulator (GUMS and GOG)• Scientific challenges: some examples• On ground spectroscopic surveys complementary to Gaia

Gaia astrometric accuracy

~10 as/yr

Earth – Moon

Gaia astrometric accuracy

Gaia astrometric accuracy

Basic Principles

Scanning law

Scanning Space Astrometry: to transform positional information into timing data

Blue

Ph

otom

eter C

CD

sB

lue P

hoto

mete

r CC

Ds

Red

Ph

otom

eter C

CD

sR

ed P

hoto

mete

r CC

Ds

Radial Velocity Spectrometer CCDs

Radial Velocity Spectrometer CCDs

42,3

5cm

Scanning Space Astrometry: to transform positional information into timing data

Obtained from differential along-scan measurements between the two FoV. The error depend on the Γ angle (0.5 μas accuracy)

Parallactic displacement along the great cicle Sun-StarSensitivity AL is proportional to sin ξ sin Γ

ξ = Sun-spin axis angle = 45º for GaiaΓ = basic angle = 106.5º for Gaia

Optimal values between astrometry requirements - that call for a large angle - and implementation constraints - such as payload shading and solar array efficiency

Absolute parallaxes

Each CCD:

-calibrated geometrically-Calibrated photometrically

Chromaticity correction:

Asymmetric aberrations, the diffraction image of Gaia is wavelength-dependent.

The polychromatic image centroid is shifted: - aberration (FoV position)- Source SED (BP, RP spectra)

Instrumental calibration

Reduction Strategy

AGIS Core Processing

100 million “well-behaved” stars

Intermediate Data Update

• Requirements at 20 μas level (10-10 rad)• Colours are needed for PSF, LSF (centroiding) • Radial velocities enter in astrometric model• relativistic model (orbit, ephemerides, time)

• Models for stars not fitting the model: • Binaries• Variable stars

• Data Volume • ~500 TB – 1PB for 5 years• 1020-21 flop • CPU time: 1sec/star – 30 years

Astrometric Global Iterative Solution

What Gaia will observe?

the Gaia Simulator: GUMS and GOG

The Gaia Simulator(s)

Gaia Universe Model Simulator

Published: Robin et al. 2012 A&AAvailable at CDS

The Gaia Simulator: MW stars

Besançon Galaxy ModelDrimmel et al. (2003) 3D extinction

Variable stars:

Stars per square-deg (log10)

(Y,X)

(Z,X)

(Z,Y)

The Gaia Simulator: galactic populations

The Gaia Simulator: extragalactic objects

Unsolved Galaxies ~3.8·106

Z < 0.8

Quasars~ 5·105

Z < 4

GOG: Gaia Object Generator

An attempt to simulate Gaia productsGUMS + a model for Gaia errors

Goals: To fill the Gaia Archive For Science Exploitation

Equatorial coordinates, units: mas (Palmer, Luri et al., 2013, in prep)

Scanning law (large number of transits)

The Galactic Center (large number of

faint stars)

Sky map of the mean parallax error

Gaia and the Magellanic Clouds

The distance to LMC and SMC

GUMS: Based on a real catalogue, 7.5·106 (LMC), 1.5 106 (SMC) with G<20

Gaia data: Large error in individual distances

Maximum Likelihood techniques are mandatory (Luri et al., 1996)Relative error in mean distance: 0.5% (LMC), 1.5% (SMC) No 3D map

SMC with OGLE (Haschke et al., 2012): Cepheids (2522 stars): 63.1 3.0 kpc , 4.7 % accuracy RR Lyrae (1494 stars): 61.5 3.4 kpc , 5.5 % accuracy

GAIA’s view R136 (LMC)

Transverse velocities ~1-2 km/s accuracy

G=12-15 mag (~10 as/yr)

de Bruijne and de Marchi, 2011

R136, the star cluster in the Tarantula (30 Doradus)

Gaia (GIBIS) HST

GIBIS: Gaia Basic Image Simulator Stellar density at G<20 ~1.4 106 stars /sqdeg

de Bruijne and de Marchi, 2011

Gaia and the distance scale

33

1912: Henrietta Leavitt discovered the key for the distance scale of the Universe  

Period-Luminosity relation (25 cepheids in the SMC)

The Cepheids

Gaia will observe ~9000 Cepheids (extrapolated from Berdnikov et al. cat)Gaia: Metallicity dependence of the PL relation

Windmark et al., 2011

Hipparcos suspected binarity in Cepheids

~ 50 % binaries, the companion star affect the brightness and motionGaia will treat several of them as binaries (astrometric orbit)

Hipparcos vs. 'ground-based' parallax

Hipparcos: no allowance for binarity, thus the motion along the orbital arc could falsify the deduced parallax value.

It is remarkable that all negative parallax values plotted in the figure belong to known binaries (open clicles).

(Laszlo Szabados, 2010)

~500 000 Quasars

- The Reference Frame - How to detect them?- Lensed QSO in Gaia survey? - Astrometry for astrophysics- …

Inertiality of the Gaia Celestial Reference Frame

Accuracy of the residual rotation (units: as/yr), Mignard (2011)

Confusion matrix

QSO with low EWs emission lines removed , they are confused with cool

(4000–8000 K) highly reddened (AV = 8–10) stars

QSO Detection

SVM (Super Vector Machine) using BP/RP and astrometryBayler-Jones et al. (2008)

BP/RP spectra for QSO (red) and stars (blue)

Number of lensed Quasars in Gaia Survey?0.6% of quasars will consist of multiple lensed QSO images (~3000)

Finet et al. 2011

AGNs

A set of selected AGNs revealed photocenter jitters at mas levelperturbations in the accretion disk emissivity? (no, Popovic et al. 2012) energetic processes occurring therein (SN, GammaRays)?

Radio-quiet 1620+172 (Mrk 877), R=16, z=0.112, 2pc/mas (Antón et al., 2011)

The transient sky by Gaia

Ground contact: 8h /day Analysis and anomaly detection at Cambridge Alerts issued in 24-48 hours after observations

See: Wyrzykowski et al. 2013, IAU 298

The Red Clump Stars The Galactic Bar (s) and the Spirals

Galactic disk space distribution function

Red clump surface density

1/ is a biased estimates of the true distance!!

Does our Galaxy have one/two bars?work in the space of the observables!

distances parallaxes

Romero-Gómez, Aguilar et al.

Does our Galaxy have one/two bars?work in the space of the observables!

Extinction is critical: A new 3D new map using Gaia and IR

Red Clump: accuracy in tangential velocities

Gaia data Gaia + IR distances (10%) Mandatory to combine Gaia and IR data

Hyper-Runaway Stars

HIP 60350 (Runaway, B-star, 3.5 kpc)

At the moment, the quality of the observational data is insufficient to pinpoint the precise origin of the star within the spiral arm (cluster birthplace?)

Gaia parallax accuracy ~10 as (G~11), 3 % accuracy in the relative parallax

Was the star originated some ≈15 Myr ago, in the Crux-Scutum spiral arm?

Irrgang, A., et al. 2010

Solar System minor bodies

~100 TNO: orbit, binarity detection, …~2·105 asteroids: orbit, rotation, shape, …Can Gaia discover new Earth Trojans?

Can Gaia discover Earth Trojan?

Solar system fossils

Solar system star formation

Oct-2010: 1st 2010TK7

Difficult from Earth:

Rather close to the Sun

Very dispersed on sky

Region of highest probability forDetection (Todd et al. 2011 )

Gaia disadvantages:

Only up to G=20High along and across scan velocity(loss of signal, out of CCD window) Is 2010 TK7 the largest? If yes, prob. detection is low

Can Gaia discover Earth Trojan?

Gaia advantages:

Earth’s L2 Lagrangian pointCo-orbital nature with ETContinuous scanning modeRegions surveyed multiple times Down to a Solar elongation of 45ºNo limitation on local zone No limitation on airmass

ET simulationsTodd et al. 2012

On-ground Spectroscopic Surveys complementary to Gaia

Gaia-ESO survey (GES)

Public large spectroscopic survey with FLAMES@VLTStarted Feb/2012 + 5 years (300 nights)Ips: Randich, Gimore + ~300 Co-Ips All stellar populations: Halo, Bulge, Thick/Thin disk + open clusters

Products: 105 Giraffe spectra (R~16000-25000)104 UVES spectra (R~47000) + ESO archive

An optical Multi-Object-Spectrograph (2017)WEAVE@ WHTCanary Island

Radial velocities 2 km/s V=20Abundances V17

The Gaia Archive

Data Archive: Goals

I. A validated and well documented set of Gaia dataII. A functional, single point access to all Gaia science dataIII. A defined API to allow the development of high throughput access

applications and visualization tools. IV. A set of advanced applications for data manipulation and visualization V. Tools and content for outreach (social impact of the mission)

IP: X. Luri (Univ. Barcelona)~300 Co-IPs

Gaia and other (future) large surveys

LSST and Gaia: complementary for studying the Milky Way

Gaia will provide calibration checks to astrometric LSST data LSST will extend the Gaia survey four magnitudes deeper.

end

Networks and coordinated projects

Scientific Exploitation: GREAT-FP7: European Union ‘Initial Training Network (32 institutions )REG: Red Española de Explotación Científica de Gaia (140 members, 30 institutions)GREAT-ESF: European Science Foundation (2011-2015) (17 countries, 90 institutions)

On Ground Complementary Data: GES: Gaia ESO Survey (2012-2016)

Gaia Data Achive: CU-9: Gaia DPAC (~300 participants)GENIUS-FP7:

Proper Motions at 20 μas/y (V=15)

• 20 μas/y = 10 m/s a100 pc (planets around 0.5 milion stars; Júpiter motion is 15 m/s)

• 20 μas/y = 1 km/s at 10 kpc (slower star’s motions detected at 10 kpc)

• 20 μas/y = 5 km/s at 50 kpc (internal LMC kinematics as the local kin. today, 5 km/s = 2.5 mas/y at 400 pc)

• 20 μas/y = 100 km/s at 1 Mpc (curva de rotación en M31?)

•Parallax accuracy 20 μas (V=15) = 1% in distance at 0.5 kpc (6D structure of the Orion complex 2pc resolution)

(MV=+10)

(MV=-10)

(MV=0)

(MV=-3.5)

General aspects

Can Gaia discover Earth Trojan?

Probability of existence of Earth trojans on stable orbits (Earth at longitude

=0), Todd et al. 2011

Fossils: Solar system formation

Oct-2010: 1st discov. 2010TK7

Difficult from Earth:

Rather close to the Sun

Very dispersed on sky

Gaia i els exo-planetes

Terceres Jornades d'Astronomia al Montsec

Resultats esperats:

• ~2000 exo-planetes (sistemes simples) detectats astrometricament.

• ~300 sistemes amb diversos planetes.

• òrbites ben determinades per ~1000 sistemes.

• ~5000 trànsits planetaris observats• Planetes amb masses fins per sota de

10 MTerra a 10 pc. 0

0.2

0.4

0.6

0.8

1

1.2

cos (")

1/01/00

1/01/01

1/01/02

1/01/03

1/07/00

1/07/01

1/07/02(")

0 0.2 0.4 0.6 0.8 1.0

Planète : = 100 mas P = 18 mois

Gaia capabilities / products

• Positions, proper motions and parallaxes for 1 billion stars (G < 20)

• Low resolution spectrophotometry for 1 billion stars, allowing estimations of Teff, logg, Av and [Fe/H]

• Radial velocities for 150 million stars (G < 16)

• Atmospheric parameters, reddening and rotational velocities for 5 million stars (G < 12)

• Detailed chemical abundances for 2 million stars (G < 11)

Proper direction:

Orbital data prec.: 150m, 2.5 mms-1

Field angles: ,

Proper direction: u

Sistema instrumental:z: Eje de spinx: Bisectriz de las dos direcciones astrométricas

Field angles

Attitude

• The attitude relates the SRS to the CoMRS (esentially the ICRS)

• Is given by A(t):

X,Y,Z components of u in CoMRS

x,y,z components of u in SRS

Expresed in quaternions:

Each CCD row calibrated geometrically

- (in,x,y), (in,x,y)

Each CCD photometrically defined- bias, flatfield, etc.

in=0,1x,y: position on the focal plane

Instrumental calibration

PSF, LSF calib.

Comparison of observed and calculated field angles

Differences explained by a lineal model as a function of a set of parameters, depending on what you want to measure

Global Iterative Solution

Attitude: B-spline coefficients.

Time interval, all the observations

Calibration: all the observations on a given column and time interval

Global Iterative Solution

Source: six astrometric parameters

All the observations of a given source

Global:

All the observations

Global Iterative Solution

Source: six astrometric parameters

All the observations of a given source

Global:

All the observations

Global Iterative Solution

• 1012 Individual measurements (transits) • 1010 Unknowns (all related, simultaneous determination)

• 5·109 stars(pos, pm,par)• 1.5·108 attitude• 10 - 50 106 calibration• Some tens of “global”

• Requirements at 20 μas level (10-10 rad)• Colours are needed for PSF, LSF (centroiding) • Radial velocities enter in astrometric model• relativistic model (orbit, ephemerides, time)

• Data Volume ~500 TB – 1PB for 5 years, 1020-21 flop • CPU time: 1sec/star – 30 years

Data reduction

WEAVE: optical MOS• For WHT • FoV = 2o

• MOS + mIFU + LIFU• R= 5k, ~1000 fibres

V=20 (R=5k, SNR=10, 1h)• R= 20k from grating change V=16 (R=20k, SNR=50, 1h)• = 0.37-1.00 μm Status: • Concept Study, 01/2011, first Science Case completed 2/2012• 03/2011 ASTRONET partners recommend North(WHT)+South(ESO) MOS• 06/2011 UK, NL commit funding for WEAVE to PDR (expected 2013)• 09/2011 IAC support construction of WEAVE• 2016: Instrument First Light

WEAVE & Gaia

• Formation scenarios for Galactic stellar halo. In-situ or accreted?– Total mass of the Milky Way out to 200 kpc– The shape of the Galactic gravitational potential within 50–100 kpc– Lumpiness of the Galactic dark matter distribution within 20–50 kpc

• The dynamics of the Galactic disk & chemical labeling– Configuration space and global phase-space constraints– Local substructures in phase-space, resonances, and stochasticity– Chemo-dynamical constraints

• Galactic open clusters– Formation and disruption– Tracers of chemical evolution of the disk

Gaia and LSST performances

Field angles: ,

Ellipse: instantaneous scan great-circle Rectangles: the two Gaia FoV (BAM = 106.5º)Sun: always 45º from the positive z axis

Comparison of observed and calculated field angles

Differences explained by a lineal model as a function of a set of parameters, depending on what you want to measure

Global Iterative Solution

Astrometric Global Iterative Solution

The Gaia Simulator: stars with planets

The Gaia simulator: extragalactic objects

Stars per square-deg (log10)

GOG

• Provides: – Epoch (transit) and combined (end-of-misssion) data – True data, data as observed by Gaia and their errors

• Is based on: – A model of the Gaia instruments – Error models provided by the CUs (DPAC) (final Gaia

data will be more complex)• Has two main simulation modes :

– The GUMS universe model (integrated in GOG)– An external list of sources provided by the user

units: as/yr (Palmer, Luri et al., 2013, in prep)The colour scale represents log density of objects in a bin size of 80mmag by 2 as/yr

Proper motion accuracy (End-of-mission)

R136, the star cluster in the Tarantula (30 Doradus)

Gaia (GIBIS) HST

de Bruijne and de Marchi, 2011

QSO with emission-line EWs less than 5000Å removed (they are confused

with cool highly reddened stars)

QSO Detection

SVM (Super Vector Machine) using BP/RP and astrometry

Està al revés?

QSO, galaxies and stars: astrometryAstrometry hardly improves the results

Bailer-Jones et al. (2008)

Gaia QSO catalogue

QSOs : crucial targets to define the Gaia Celestial Reference Frame (GCRF)

Unprecedented precision in photo-center position: astrometric stability of QSOs and the possible physical consequences inner quasar structure and physical processes

AGNsRadio emitter AGNs: defining the quasi-inertial International Celestial Reference Frame (ICRF). will help in the alignment between optical (Gaia) and radio reference frame

A set of selected AGNs revealed photocenter jitters at mas levelperturbations in the accretion disk emissivity? (no, Popovic et al. 2012) energetic processes occurring therein (SN, GammaRays)?

Radio-quiet 1620+172 (Mrk 877), R=16, z=0.112, 2pc/mas (Antón et al., 2011)

The Supernovae

≃ 6000 SNe (Type Ia + CC) SNe over the 5-year mission (G<19)Most distant observed type Ia SNe will be at 500Mpc (z 0.12). ≃ ≃About 1/3 of the SNe is expected to be observed before maximumScience Alert programme stablished

The Gaia Scanning Law

End-of-mission number of transits per source

The Gaia Scanning Law

Microlensing events during the Gaia mission

The Gaia Simulator: microlenses

Prediction of astrometric microlensing events during the

Gaia mission 43 astrometric microlensing effect during the Gaia mission. The effect allows a precise measurement of the mass of a

single star that is acting as a lens

The 2 events that should be observable with Gaia are plotted as green squares