Transcript GAIA A Stereoscopic Census of our Galaxy

ESA Gaia: Expectation
for Astroparticle Physics
René Hudec, Vojtěch Šimon, Lukáš Hudec
& Collaborators & Gaia CU7 consortium
Group of High Energy Astrophysics
Astronomical Institute of Academy of Sciences of the Czech
Republic, Ondřejov, Czech Republic
ISDC Versoix, Switzerland
Santa Fe GRB Workshop 2007
Reference: http://sci.esa.int/gaia/
ESA Mission Gaia
Unraveling the chemical and dynamical
history of our Galaxy
Albeit focusing on astrometry, Gaia will also provide
spectrophotometry for all objects down to mag 20 over 5 years
operation period. Typically 50 to 200 measurements per object
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including optical counterparts of HE sources.
Gaia: Design Considerations
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Astrometry (V < 20):
•
Photometry (V < 20):
– completeness to 20 mag (on-board detection)  109 stars
– accuracy: 10–25 μarcsec at 15 mag (Hipparcos: 1 milliarcsec at 9 mag)
– scanning satellite, two viewing directions
 global accuracy, with optimal use of observing time
– principles: global astrometric reduction (as for Hipparcos)
– non-negligible fraction TeV/VHE sources including OTs and OAs of GRBs
will be within the detection limit
– dark matter in the Galactic disk study measuring the distances and
motions of K giants
– astrophysical diagnostics (low-dispersion photometry) + chromaticity
 Teff ~ 200 K, log g, [Fe/H] to 0.2 dex, extinction
•
Radial velocity (V < 16–17):
– application:
• third component of space motion, perspective acceleration
• dynamics, population studies, binaries
• spectra: chemistry, rotation
– principles: slitless spectroscopy using Ca triplet (847–874 nm)
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Gaia: Complete, Faint, Accurate
Hipparcos
Gaia
Magnitude limit
Completeness
Bright limit
Number of objects
12
7.3 – 9.0
0
120 000
Effective distance
limit
Quasars
Galaxies
Accuracy
1 kpc
None
None
1 milliarcsec
Photometry
photometry
Radial
velocity
Observing
programme
2-colour (B and V)
None
Pre-selected
20 mag
20 mag
6 mag
26 million to V = 15
250 million to V = 18
1000 million to V = 20
1 Mpc
5 x 105
106 – 107
7 µarcsec at V = 10
10-25 µarcsec at V = 15
300 µarcsec at V = 20
Low-res. spectra to V = 20
15 km/s to V = 16-17
Complete and unbiased
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GAIA capabilities
<0.1% for 700 000 stars
Distances:
<1% for 21 million
million
<10% for 220
Transverse motions:
<0.5% km/s for 44 million <3 km/s for 210 million <10 km/s for 440
million
Radial velocities to a few km/s complete to V=17-18
15-band photometry (250-950nm) at ~100 epochs over 4 years
Complete survey of the sky to V=20, observing 109 objects:
108 binary star systems (detected astrometrically; 105 orbits)
200 000 disk white dwarfs
50 000 brown dwarfs
50 000 planetary systems
106-107 resolved galaxies
105 quasars
105 extragalactic supernovae
105-106 Solar System objects (65 000 presently known)
Satellite and System
• ESA-only mission
• Launch date: 2011
• Lifetime: 5 years
• Launcher: Soyuz–Fregat from CSG
• Orbit: L2
• Ground station: New Norcia and/or Cebreros
• Downlink rate: 4–8 Mbps
• Mass: 2030 kg (payload 690 kg)
• Power: 1720 W (payload 830 W)
Figures courtesy EADS-Astrium
Schedule
2004
2000
2008
2016
2012
2020
Concept & Technology Study
(ESA)
ESA acceptance
Re-assessment:
Ariane-5  Soyuz
Technology
Development
Design, Build,
Test
Launch
Cruise to L2
Observations
Data
Analysis
Early Data
Catalogue
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Payload and Telescope
Two SiC primary mirrors
1.45  0.50 m2 at 106.5°
Rotation axis (6 h)
Basic angle
monitoring system
SiC toroidal
structure
(optical bench)
Superposition of
two Fields of View
(FoV)
Combined
focal plane
(CCDs)
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Figure courtesy EADS-Astrium
Astrometric instrument: Light path
1
2
3
4
Photometry Measurement Concept
Blue photometer:
330–680 nm
Red photometer:
640–1000 nm
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Figures courtesy EADS-Astrium
1050
18
650
35
1000
16
30
950
Blue photometer
wavelength (nm)
600
550
25
500
20
450
15
400
10
350
5
300
0
0
5
10
15
20
AL pixels
25
30
35
wavelength (nm)
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spectral dispersion per pixel (nm) .
700
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Red photometer
900
12
850
10
800
8
750
6
700
4
650
2
600
0
0
5
10
15
20
25
30
35
AL pixels
RP spectrum of M dwarf (V=17.3)
Red box: data sent to ground
White contour: sky-background level
Colour coding: signal intensity
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Figures courtesy Anthony Brown
spectral dispersion per pixel (nm) .
Photometry Measurement Concept (2/2)
Figure courtesy Alex Short
Focal Plane
104.26cm
42.35cm
Basic
Angle
Monitor
Basic
Angle
Monitor
Red Photometer CCDs
Wave
Front
Sensor
Blue Photometer CCDs
Wave
Front
Sensor
Radial-Velocity
Spectrometer
CCDs
Star motion in 10 s
Sky Mapper
CCDs
Total field:
Astrometric Field CCDs
Sky mapper:
- detects all objects to 20 mag
- active area: 0.75 deg2
- rejects cosmic-ray events
- CCDs: 14 + 62 + 14 + 12
- FoV discrimination
- 4500 x 1966 pixels (TDI)
- pixel size = 10 µm x 30 µm
Astrometry:
= 59 mas x 177 mas - total detection noise: 6 e-
Photometry:
- two-channel photometer
- blue and red CCDs
Spectroscopy:
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- high-resolution spectra
- red CCDs
On-Board Object Detection
• Requirements:
– unbiased sky sampling (mag, color, resolution)
– no all-sky catalogue at Gaia resolution (0.1 arcsec) to V~20
• Solution: on-board detection:
– no input catalogue or observing programme
– good detection efficiency to V~21 mag
– low false-detection rate, even at high star densities
• Will therefore detect:
–
–
–
–
variable stars (eclipsing binaries, Cepheids, etc.)
supernovae: 20,000
microlensing events: ~1000 photometric; ~100 astrometric
Solar System objects, including near-Earth asteroids and KBOs
– fraction of OTs and OAs of GRBs
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Sky Scanning Principle
45o
Spin axis
Scan rate:
Spin period:
45o to Sun
60 arcsec/s
6 hours
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Figure courtesy Karen O’Flaherty
Scanning law
Observations over 5 months
Ecliptic co-ordinates
GAIA and our Galaxy
10 as = 10% distances at 10 kpc
10 as/yr = 1 km/sec at 20 kpc
Data Processing Concept (simplified)
From ground station
Community access
Overall system
architecture
ESAC
Object processing
(shell tasks)
+ Classification
CNES, Toulouse
Ingestion, preprocessing,
data base + versions,
astrometric iterative solution
ESAC (+ Barcelona + OATo)
Photometry
Cambridge (IOC)
+ Variability
Geneva (ISDC)
Data simulations
Barcelona
Spectroscopic
processing
CNES, Toulouse
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Status and contributions to be confirmed
*DPAC:
Data Processing and Analysis Consortium
**DPACE: DPAC Executive
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Czech Republic expected to join ESA as a full member in Jan 2009
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Gaia CU7 Sub-workpackage
on Optical Counterparts of
High-Energy Sources
René Hudec & Collaborators
Leuven, Nov 9-10, 2006
Motivation of the Gaia CU7 Subworkpackage on Optical Counterparts of
High-Energy Sources
• Many of HE&VHE sources (including OAs and OTs
of GRBs) have also optical emission, mostly variable
and accessible by Gaia
• Monitoring of this variable optical emission provides
important input to understanding the physics of the
source
• Multispectral analyses
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Optical Counterparts of High Energy Sources
The objective of the work package:
• The investigations and analyses of optical counterparts of high
energy astrophysics sources based on Gaia data and complex
analyses with additional data. Specifically:
• For selected targets, multispectral analyses using Gaia and other
databases (such as the satellite X-ray and gamma-ray data,
optical ground-based data etc) may be feasible.
• Analyses of long-term light changes and their evolution
• Analyses of active states and flares
• The study and understanding of related physical processes.
• Spectrophotometry, relation of brightness and spectrum/colour.
• For selected sources, dedicated complex analyses.
• Statistics of the whole sample of objects.
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Some examples
• LMXRB
• HMXRB
• Optical Afterglows and Optical
Transients of GRB
Optical LC of OT of
GRB060116,
Jelinek et al. 2006
Long-term optical changes of Sco X-1/V818
Sco, Hudec 1981
Inactive state optical LC of Her X-1/HZ Her, Hudec and Wenzel 1976
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Rapidly evolving light curves of some
LMXRB, Muhli et al., 2004
Thermonuclear bursts related to NS?
Gaia: Optically faint LMXB often suffer by
poor optical coverage/analyses, especially
on long-term time scales. Here can Gaia
provide important inputs.
Ser X-1/MM Ser LMXRB & X-ray burster
Wachter 1997
Optical bursts related to X-ray bursts:
reprocessing of X-rays in a matter near the
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B magnitudy
8% 1%
1
13%
2
3
38%
40%
4
5
Even gamma-ray sources do
have optical counterparts
accessible by Gaia
Legend - B
1 = 2,29 - 5
2 = 5 -10
3 = 10 - 15
4 = 15 - 20
5 = 20 - 23
V magnitudy
5% 1%
17%
1
2
34%
3
4
43%
5
Legend - V
1 = 2,39 - 5
2 = 5 -10
3 = 10 - 15
4 = 15 - 20
5 = 20 - 21
>90% accessible with Gaia
Optical B and V magnitudes of optically identified INTEGRAL
gamma-ray sources … most are brighter than mag 20, and
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more than half are brighter than mag 15
Gaia and GRBs: Photometry
• There will be a variety of OTs detected by Gaia
• The real OTs and OAs of GRBs can be, among
these,
recognized
according
to
their
characteristic power-law fading profie
• However, the sampling provided by Gaia, is not
optimal for these goals, hence not always we
can expect realiable and confirmed detection of
OT of GRB based only on photometry by Gaia
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Gaia and GRBs: Spectroscopy
• The primary strength of Gaia for GRB
study is the fine spectro-photometry
• The OAs of GRBs are known to exhibit
quite typical colors, distiguishing them
from other types of astrophysical objects
(Simon et al. 2001, 2004)
• Hence a realiable classification of OTs
will be possible using this method
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Specific
colors of OAs
of GRBs
(Simon et al., 2001,
2004)
Notice the prominent
clustering of colors
and negligible color
evolution during
decline.
V-R vs. R-I diagram of OAs of GRBs (t-T0 <10.2 days) in observer frame, corrected for
the Galactic reddening. Multiple indices of the same OA are connected by lines for
convenience. The mean colors (centroid) of the whole ensemble of OAs (except for
GRB000131) are marked by the large cross. The colors of SN1998bw are shown only
for comparison. The representative reddening paths for EB-V=0.5 are also shown.29
Positions of the main-sequence stars are included only for comparison.
Gaia CU7 Sub-workpackage
on Cataclysmic Variables
René Hudec & Collaborators
Leuven, Nov 9-10, 2006
Cataclysmic Variables and Related Objects
The objective of the sub-work package:
• The investigations and analyses of Cataclysmic Variables
and related objects (including supernovae, novae,
recurrent novae, nova-like variables, dwarf novae, polars,
intermediate polars, symbiotic stars) based on Gaia data
(photometry and spectrophotometry) as well as complex
analyses with additional data.
• Some of the CVs are candidates for VHE emission (SNe,
AE Aqr, AM Her...)
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SN 1987A
Nova V1500 Cyg
RS Oph Recurrent Nova
U Gem Dwarf Nova
Z Cam Dwarf Nova
Z And Symbiotic Variable
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Gaia CU7 Sub-workpackage
on AGN
Gaia and AGN
• Gaia will detect all AGN brighter than
mag 20
• Photometry and spectro-photometry
• Including TeV AGN/blazars
• Providing valuable simultaneous and
quasi-simultaneous optical data for TeV
blazars
• Automated recognition of AGN by their
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spectra, searches for spectral changes
Variability studies based on low
dispersion spectra
Application of algorithms developed for
digitized astronomical archival plates
(Hudec L., 2007) on Gaia
Simulated low dispersion Gaia
spectrum
Real low dispersion spectrum
from digitized Schmidt spectral
plate
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Relation of spectral and
photometric variations
T. Jarzebowski,
1959
X Cam
Mira Variable
Spectral Variations
M0 to M6.5
Amplitude 1.4 mag
in R 36
Example spectra of cataclysmic variables &
blazars (digitised Hamburg Survey)
CV
CV
CV
CV
Blazar
Blazar
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Novel algorithms for automated
analyses of digitized spectral plates
• Developed by informatics students
• Automated classification of spectral
classes
• Searches for spectral variability (both
continuum and lines)
• Searches for objects with specific spectra
• Correlation of spectral and light changes
• Searches for transients
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The Motivation
• The archival spectral plates taken with
objective prisma offer the possibility to
simulate the Gaia low dispersion spectra and
related procedures such as searches for spectral
variability and variability analyses based on
spectro-photometry
• Focus on sets of spectral plates of the same sky
region covering long time intervals with good
sampling
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Automatic classification of stellar
objective prism spectra on digitised
plates, a simulation and a feasibilty
study for low-dispersion Gaia spectra
Left:
investigated
spectrum
Right:
Calibration
spectrum
(Hudec L.,
2007)
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The End
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