Virgo status and its upgrades - Rencontres de Moriond
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Virgo status and its upgrades Original talk from Jo van den Brandt, Nikhef & VU University Amsterdam & and Alessio Rocchi, INFN Roma Tor Vergata. Presented by Marie Anne Bizouard, ARTEMIS CNRS/Observatoire de la Cote d’Azur/Université de Nice on behalf of the Virgo collaboration. Moriond Gravitation 2019, La Thuile 24 March 2019
LIGO and Virgo
Observe together as a network of GW detectors. LVC have integrated their data analysis.
2
Observing scenarios
Observing run 3 starts on April 1st!
60-85
3
Advanced Virgo
Most infrastructure installed for Advanced Virgo. It features many improvements with respect to Virgo and
Virgo+. However the absence of Signal Recycling has great impact.
Instrumentation improvements for Observing run 2
• Larger beam: 2.5x larger at ITMs
• Heavier mirrors: 2x heavier
• Higher quality optics: residual roughness < 0.5 nm
• Improved coatings for lower losses:
absorption < 0.5 ppm, scattering < 10 ppm
• Reducing shot noise: arm finesse of cavities are
3 x larger than in Virgo+
• Thermal control of aberrations: compensate for cold
and hot defects on the core optics:
ring heaters
double axicon CO2 actuators
CO2 central heating
diagnostics: Hartmann sensors & phase cameras
• Stray light control: suspended optical benches in
vacuum, and new set of baffles and diaphragms to
catch diffuse light
• Improved vacuum: 10-9 mbar instead of 10-7 mbar
5
Scientific output: new era in physics & astronomy
Astrophysics of compact objects Fundamental physics
Cosmology Multi-messenger astronomy
6
Scientific output: new era in physics & astronomy
Astrophysics of compact objects Fundamental physics
Cosmology Multi-messenger astronomy
See all presentations from the
LIGO Scientific collaboration
&
the Virgo collaboration
7
Catalogue of known GW sources
released on December 2018
“GWTC-1: A Gravitational-Wave Transient Catalog of Compact Binary Mergers
Observed by LIGO and Virgo during the First and Second Observing Runs”, The LIGO &
Virgo Collaboration, arXiv:1811.12907
●
Extract information on masses, spins, energy radiated, position, distance, inclination,
polarization. Population distribution may shed light on formation mechanisms.
8
GW data going public … including Virgo data!
https://www.gw-openscience.org O2 data have been released on Feb 28th
9
Towards O3
11
Projected sensitivity evolution for Virgo
From the 2013 ‘‘Observing Scenario’’, arXiv:1304.0670. We projected at least 60 Mpc for O3.
Note that LIGO aims at > 120 Mpc
All four test masses are suspended with steel wires
12
12Towards O3: Virgo performance at the end of O2
Advanced Virgo has
no signal recycling
LIGO-Virgo sensitivities on
August 17th 2017
13Hardware changes after O2
14Hardware changes : Nov 2017 – Mar 2018
15Squeezer installation & commissioning
● The AEI squeezer installed in Virgo’s
DET lab.
– Fully functional and an automated stand-
alone in-air squeezed light laser source.
– Approximately 1 m2 in footprint.
– Duty cycle almost 100%.
Phase noise about 3 mrad.
– Easy to maintain.
● Lab experiments have shown that:
– this squeezer can provide up to 14 dB of
squeezing for downstream application at
very low pump powers.
– 12 dB measured with diagnostic
homodyne detector introducing additional
loss, therefore derived 14dB for
application.
Delivered in Cascina on January 2018 16And then started the commissioning ….
● Reach a good sensitivity already in June
172018 commissioning
● Best BNS range 35 Mpc in June;
● Following the commissioning plan, ITF input
power increased to 25 W (now 18 W).
– Long tuning and recovery required.
– Timing distribution system upgraded.
– Intracavity losses reduced.
– Two campaigns for stray light
mitigation on detection benches.
– Several issues (laser amplifier power
unit, OMC1, SSFS/IMC and SDB2
minitower suspension) slowed the
operations.
● Difficult summer with very low duty cycle.
● New mystery noise appeared at low frequency.
● A lot of work done with no sensitivity pay-off.
182018 commissioning
● October 2018: go back to 18 W instead of 25W → increase of the duty cycle
→ possibility to investigate
A. Rocchi - AdV commissioning
192018 fall commissioning
● Low frequency “f-2..3” origin found: mirror charged by faulty electronics (random movement
of charge on mirror surface).
● Mid frequency noise investigation.
● Inject squeezed light.
202018 fall commissioning
Discharger prototype
21Squeezed light in advanced Virgo
● 12 dB produced by the source.
● Measured a peak SQZ injection of almost 3 dB (O3 target), equivalent to increasing
the input power by a factor of 2 (from 18 W to 36 W).
● BNS range increases by 2-3 Mpc when squeezed light is injected.
22Commisioning: other activities
● Injection fast unlocks fixed
● Output mode cleaners match losses decrease
● Detection bench stray light hunting
● Detection bench suspension fixed
23Best sensitivity reached in feb 2019
BNS 55 Mpc with 18 W
and squeezing
Obs. Scenario plots evaluated @ 25 W of
input power
24Virgo sensitivity: significant improvement wrt O2
Comparison to the best sensitivity obtained in O2. Monolithic suspensions are now installed.
Flat noise contribution in mid-frequency range, and significant 50 Hz noise
25
25O3 startup Virgo sensitivity
26O3 startup LIGO-Virgo sensitivity
O3 starts on April 1st!
27Low-latency searches during O3
● LIGO/Virgo low-latency alerts for transient event candidates
– CBC LL searches + Burst LL searches
– Notices and circulars available through the Gamma-ray Coordinates Network (GCN)
– Event candidates will be publicly available in https://gracedb.ligo.org
● MDC events are there now: search “category: MDC”
– There will be no human vetting for Preliminary notice
● LIGO/Virgo Public Alerts User Guide & Support
– https://emfollow.docs.ligo.org/userguide/quickstart.html
● What goes public?
– False alarm rate, sky map. Binaries: distance, probability of {BNS, BBH, NSBH,
MassGap, and terrestrial}, probability of NS present, probability of non-zero disk mass.
Bursts: Central frequency, duration.
28Low latency searches during O3
https://emfollow.docs.ligo.org/userguide/index.html
29What’s next?
30Towards a global network
KAGRA expected to join LIGO and Virgo in Observation run 3
31
31Planned observing timeline
One-year O3 planned to start in April 2019 with about twice the sensitivity in O3 (thus about 23 in
rate). During O3 LIGO and Virgo will release Open Public Alerts
Observation run O3
●
Three detectors and perhaps 1 event per week
●
KAGRA expected to join at the end of O3
Prospects
●
Contribute
for to Localizing
Observing and sky localization andwith
GW Transients PEaLIGO, AdV and KAGRA 7
~20% in 20 sq deg HLV 2019
Early Mid Late Design
60-80 60-100 120-170 190
Mpc Mpc Mpc Mpc
LIGO O1 O2 O3
25-30 65-85
60-85 65-115 125
Mpc Mpc Mpc Mpc
Virgo O2 O3 ~60% in 10 sq deg HIKLV 2024
25-40 40-140 140
Mpc Mpc Mpc
KAGRA
2015 2016 2017 2018 2019 2020 2021 2022 2023
Fig. 2 T h e p l a n n e d s e n s i ti v i ty ev o l u ti o n a n d o b s e r v i n g r u n s o f th e a L I G O , A d V a n d K A G R A d e te c to r s
B. P. Abbott et al., Prospects for Observing and Localizing Gravitational-Wave Transients 32
o v e r th ewithc o mAdvanced
i n g y e a r s .LIGO,
T h e c Advanced
o l o r e d b a r sVirgo
s h o wand
th eKAGRA,
o b s e r v i n2016,
g r u n s ,Living
w i th thRev.e e x pRelativity
e c te d s e n s i19
ti v i ti e s g i v e n b y
th e d a ta i n F i g u r e 1 f o r f u tu r e r u n s , a n d th e a c h i e v e d s e n s i ti v i ti e s i n O 1 a n d i n O 2 . T h e r e i s s i g n i fi c a n t
u n c e r ta i n ty i n th e s ta r t a n d e n d ti m e s o f p l a n n e d th e o b se r v i n g r u n s , e s p e c i a l l y f o r th o s e f u r th e r i n th e f u tu r e ,Advanced Virgo+
● Upgrade of Advanced Virgo
● Goal: sensitivity increase from ~100 Mpc to more than 200 Mpc
● Phase 1 (no invasive work):
– Signal recycling installation
– Higher laser power (O3 with 18 W)
– Frequency dependent squeezing (frequency independent squeezing already
done in advanced Virgo)
– Newtonian noise cancellation
● Phase 2 (invasive work)
– High power laser (200 W)
– Larger beams → 12 cm on end test masses
– 100 Kg test masses → end test masses, TBC on input test masses
– Better coating: depending on R&D results at the end of Phase I
33Newtonian Noise Cancellation Improvements to the infrastructure are expected to have a large impact Noise at central Building is about an order of magnitude higher than the noise in the vicinity of Virgo Need for emphasis on smart infrastructure for gravitational wave observatories • Smart infrastructure design • Newtonian noise modeling of infrastructure noise • HVAC modification
AdV+ upgrade and extreme mirror technology
Laboratoire des Matériaux Avancés LMA at Lyon produced the coatings used on the main mirrors of the two
working gravitational wave detectors: Advanced LIGO and Virgo. These coatings feature low losses, low
absorption, and low scattering properties
Features
- Flatness < 0.5 nm rms over central 160 mm of mirrors by using ion beam
polishing (robotic silica deposition was investigated)
- Ti:Ta2O5 and SiO2 stacks with optical absorption about 0.3 ppm
Expand LMA capabilities for next generation
LMA is the only coating group known to be capable of scaling up
LMAAdvanced Virgo+ planning
phase1 phase2
36Advanced Virgo+ anticipated sensitivities
37Summary
● Huge effort of commissioning, noise hunting, detecto characterization in the last year
→ Virgo is ready for O3 with almost the promised sensitivity.
● Virgo data are flowing through the low latency search pipelines.
● O3 will provide more CBC GW sources and maybe new type of sources: NSBH, intermediate
black hole mergers, core collapse supernovae, etc ...
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