Deblending issues working report

MontePorzio 16-04-08 CU5#DU11 Luigi Pulone@ INAF-OA Roma

• INAF - Teramo Observatory: Anna Piersimoni, Giorgia Busso

• INAF - Rome Observatory (Monte Porzio Catone): Giacinto Iannicola, Luigi Pulone, Marco Castellani

• ASI – ASDC (Frascati) : Licia Troisi, Roberto Buonanno, Giuliano Giuffrida

Main Task Obtain a clean spectrum for every observed

source, resolved in the astrometric field

DU11 in CU5: Leiden (NL), Cambridge (UK), Roma,Teramo (IT)

Data Processing and Analysis Consortium

ESA Gaia project team ESA Ground segment oversight

GAIA Science Team DPAC

CU3Core processing

CU1System architecture

CU6Spectroscopic processing

CU5Photometric processing

CU2Simulazioni

CU4Object analysis

CU7Variability analysis

CU8Astrophysical parameters

Coordination Unit 5

Riduzione fotometrica e calibrazione sia in banda G che negli spettri

• Estrazione dei parametri delle identificazioni per ogni passaggio nel campo astrometrico

• Elaborazione ed accumulazione dei dati in banda G, RP, BP

• Identificazione stelle standard, variabili, analisi

oggetti multipli

• Calibrazione interna ed esterna dati fotometrici

• Photometric science alerts

Gli obbiettivi di GAIA

Accuratezza-4 μarcsec a V=10 10 μarcsec a V=15 0.2 marcsec a V=20

-Velocità radiali con accuratezza di qualche km/s complete fino a V=17.5

- Survey celeste con risoluzione spaziale di 0.1 arcsec fino a V=20

- spettrofotometria multi-epoca fino a V=20

- definizione di un sistema inerziale legato ai quasar più lontaniRisultati

- GAIA posizionerà 300 milioni di stelle nello spazio delle fasi a 6 dimensioni e 1 miliardo di stelle nello spazio delle fasi a 5 dimensioni

Formazione stellare nella Via Lattea

Astrofisica stellare

Struttura Galattica

Fisica fondamentale

Sistema di riferimentoSistema

solarePianeti extrasolari

Binarie e nane brune

Confronto fra Hipparcos e GAIA

Oggetti

galassie

quasarSupernovae extrag.

Nuovi asteroidibinarie

Nane bianche

Nane brune

Sistemi planetari

Catalogue

Schedule

2000 2004 2008 2012 2016 2020

Acceptance

Technology Development

Design, Build, Test

Launch

Observations

Analysis

Early Data

Concept & Technology Study ESA SCI 2000(4)

Re-Assessment: Ariane Soyuz

To L2

Assumed start of Phase B2

Satellite and System

• Mass: 1700 kg (payload 800 kg)• Power: 2000 W (payload 1200 W)

• ESA only mission• Launch date: 2011 • Lifetime: 5 years• Launcher: FREGAT• Orbit: L2• Ground station: Perth or Madrid• Data rate: 1 Mbps

Il percorso ottico

spettrofotometro B

spettrofotometro R

GAIA – Simulazione campo stellare media densità

15 BP/ RP Flux extraction

Time intervalidentif iers

Scan coverage

I oADPCdata-base

Raw BP/ RPimages

Raw BP/ RPimages

Apply basiccalibrations 15.2

Calibrated BP/ RPimages

Evaluate sourcecrowding attransit level

15.3

I dentif y observationswithin scan coverage

15.1

I solatedimages

Crowdedimages

Basic f luxextraction

15.4Crowded f ield

f lux extraction 15.5Extracted and cleaned

BP/ RP spectra

I oADPCdata-base

I oADPCdata archive

I oADPCdata archive

Nominalattitude

evaluation

4.2

AB Apr. 2007

I oADPCdata-base

Calibrationf iles

ESAC data base

Auxilliary dataG, source positions,

window conf igurations,etc

OA Teramo

OA Roma, ASI-ASDC

Teramo group• Background modelling

• Studying relationships between AL and AC size of the source and APs

• Source crowding evaluation at source and transit level

• Create connected groups on the basis of the contamination degree

• Individuate isolated objects

BP photometer:AC width vs. G mag

AC

AL

BP photometer:AL length vs. G mag

High density regions, like Galactic bulge low-extinction regions and central regions of the Large Magellanic Cloud, present a challenge both for board data-handling and for the ground-based reduction while being crucial for the Gaia science case.

A recent result: expected frequency of the deblending procedure for the whole mission lifetime (~10%) taking into account the overlapping of the two field of view.

Figures from Marrese & Busso 2007

● Deblending of connected groups

due to:

• overlapping of spectra of different sources in connected windows

• objects in nearby windows whose spectra extend into the program window

• objects for which the on-board detection software has not assigned a window • barely detectable sources beyond the survey magnitude limit (20 < G < 22).

Rome group

The numerical approach

The analytical approach, has shown some limitations in reproducing high metallicity and low temperature spectra.

The Rome group is now developing and testing a new deblending technique based a Marquardt-like method for non linear least square minimization.

This approach is much more straightforward and makes use of the entire morphology of the spectrum simultaneously in both the Blue and Red bands.

First results appear encouraging.

new approach

template library 3500 < Teff <

20000°K, -5.00 < [M/H] <

1.00 comparison between templates and input spectrummodels interpolation

OLD ANALYTICAL vs NEW NUMERICAL APPROACH

OLD

NEW

M/H = -5

T=8000 K

Logg=4.5

Av=0.

testT = 9250°K, [M/H]= -4.5, -0.2, 1.0

9250°K

[M/H] Teff Teff/Teff

Simulated B Flux

Fitted B flux

fB/fbSimulat

ed R Flux

Fitted R Flux

fR/fR

-4.5 9112 0.015 49564 49263 0.0061 28014 27873 0.0050

-0.2 9254 0.0004 49006 49274 0.0055 27626 27349 0.0100

1.0 9244 0.0006 49345 49064 0.0057 27202 27250 0.002

Two blended spectra in the same window

Teff=20000°K, [M/H]=-4.5 + Teff=9000°K, [M/H]=0.00Shift: 10 pixel

Recovering of blended spectra

Teff Teffest Teff/Teff

Simulated B Flux

Fitted B flux

fB/fbSimulat

ed R Flux

Fitted R Flux

fR/fR

9000°K 9393 0.0437 48346 48740 0.0081 27113 27115 0.0000

20000°K 20000 0.0000 54101 50466 0.0672 20822 19526 0.0622

Teff=20000°K, [M/H]=-4.5 + Teff=9000°K, [M/H]=0.00Shift 10 pixel

Central star: V=13 T=6000 [M/H]=0Blended 1: V=14 T=10000 [M/H]=0.5 dX=15 px dY=2 pxBlended 2: V=15 T=8000 [M/H]=-0.5 dX=13 dY=3

Next steps:

• Include log g into the reference theoretical template

• Take into account the Av

• Consider the paving strategy, cut windows etc. to rebuild connected and contaminated spectra