1. Gravitational Wave-related projects at OAR
Virgo/LIGO + eLISA Sources
Multimessenger follow up
Instrumentation
Virgo EGO Science Forum (VESF)
Luigi Stella
(with thanks to Enzo Brocato and Marica Branchesi for several slides) 1

2. Double White Dwarf Binaries (AM CVn-like)
Nov 2002
Nov 2001
RXJ : a double degenerate binary
system (2WDs) with an orbital period of 5.4min !!
One of the best target for gravitational wave
Detection by eLISA

3. Magnetars: Bursts energy release ~1038-1041 ergs subsecond duration
- often emitted in bunches

4. SGR 1806-20: Giant Flare of 2004 Dec 27
(Palmer et al. 2005
Hurley et al. 2005)
Moon reverberation seen !
(Mereghetti et al. 2005)

5. The B-field of Magnetars
Very strong internal B-fields in a newborn differentially rotating fast-spinning neutron star
For initial spin periods of Pi∼1–2 ms, differential rotation can store ∼1052(Pi/1 ms)2 ergs,
that can be converted into a magnetic field of up to 3x1017 (Pi/1ms)-1 G.
(efficient dynamo might be limited to ~3x1016 G) (Duncan & Thompson 1992) Bd Bt
Fast spin (few ms) and
differential rotation generate
internal toroidal field B > 1015 G
Bd ~ G outer dipole field (spin-down, pulsations)
inferred from spin-down rate (and confirmed through the
energetics and fast variability properties of the “ringing tail”
of Giant Flares from SGRs)
Bt > 1015 G inner toroidal field (energy reservoir):
lower limit from: L(persistent) x age ~ 1047 ergs

6. Newborn Magnetars as Gravitaional Wave Sources
(for Virgo Cluster distance, 20 Mpc)
GW signal at ~1 kHz evolving in 1 week
- Consider initial spin period of 2ms
Most promising region is Bt > G and Bd < 1014 G
Required no. of templates is very large
Expected magnetar birth rate in the ~2000 galaxies of Virgo: ~ 1 yr-1 !
Potentially Very Interesting GW Event Rate in Advanced LIGO/Virgo-class instruments
~ 1 week, ~ 108cycles
2x1016 G
6x1016 G

7. Short Gamma-Ray Bursts
GRBs duration distribution is bimodal (e.g. Briggs et al. 2002)
0.1-1 s -> Short bursts
s -> Long bursts
Short GRBs are harder than long GRBs
(e.g. Fishman & Meegan, 1995;Tavani 1996).

8. GRB970228: the 1st X-ray and Optical afterglow
Fast follow up with the BeppoSAX-NFIs (8hr) led to the discovery of a bright unknown X-ray source.
A second pointing 3 days after showed that source had faded.
(Costa, et al., 1997)
Accurate (~1 arcmin) X-ray position led to the identification of a fading optical source from ground based telescopes
(Pedichini et al 1997)
(Van Paradijs, et al., 1997)

9. GRB970508: the 1st redshift GRBs have: X-ray afterglows > 90%
Images in the 2-10 keV range by the BSAX WFC ( sec after the GRB) and by the BSAX MECS (6 hrs and 3 days).
The BSAX observation led the Caltech group to the measurement of the first redshift and Frail et al to the discovery of the 1st radio afterglow and direct measurement of relativistic expansion
GRBs have:
X-ray afterglows > 90%
Optical afterglows ~ 40% - 50%
Radio afterglows ~ 35% - 40%
Metzeger et al., 1997
Long GRBs: cosmological distances !

10. Swift
Instrumentation
Burst alert telescope (BAT) keV
X-ray telescope (XRT) keV
UV-optical telescope (UVOT) U-I
- USA, I, UK mission
dedicated to GRB Science
Burst Alert Telescope triggers on GRB, calculates position to < 4 arcmin
Spacecraft autonomously slews to GRB position in s
X-ray Telescope determines position to < 5 arcseconds
UV/Optical Telescope images field, transmits finding chart to ground
BAT Burst Image
T<10 s,  < 4'
BAT Error
Circle
XRT Image
T<100 s,  < 5''
T<300 s
UVOT Image

11. Host Galaxies of Short GRBs
- Short GRBs are located inside or close to early type galaxies with low star
formation activity, BUT some are found in galaxies with star formation activity.
GRB050509b
GRB050709
Short GRBs are NOT associated to Supernovae
Short GRB are at cosmological distances but at smaller redshifts than Long GRBs
Short GRB are ~100 times less energetic than Long GRBs

12. Coalescing binary models
Association of Short GRBs to low SFR galaxies + absence of SN :
Long delay (Gyrs) between the formation of the neutron star (or black hole) and the Short GRB explosion.
Merging (or Coalescing) binary models for Short GRBs
Neutron Star + Neutron star (NS-NS) or Neutron Star + Black hole (NS-BH)
Strong Gravitational Wave Sources !
Cartoon of the proposed model for GRB-supernovae from rotating black
holes (not to scale): core-collapse in an evolved massive star produces an active MeV-nucleus
consisting of a rotating black hole (Woosley 1993; Brown et al. 2000) surrounded by a torus
which may be magnetized with the magnetic field of the progenitor star (Paczynski 1998).
The torus assumes a state of suspended accretion, wherein it catalyzes black hole-spin energy
at an efficiency given by the ratio η = T /H of the angular velocity T of the torus and H
of the black hole. Because the nucleus is relativistically compact, the torus radiates this input
predominantly into gravitational radiation, and, to a lesser degree, into magnetic winds and
MeV-neutrino emissions. A small fraction of about θ4
H of black hole-spin energy is released in
baryon-poor jets along open magnetic flux-tubes along the rotational axis of the black hole,
where θH denotes the half-opening angle on the event horizon. This output serves as input
to the GRB-afterglow emissions. As these jets punch through the remnant stellar envelope
(MacFadyen & Woosley 1999), the GRB may be delayed by seconds (Woosley et al. 1999),
and thereby appear after the onset of gravitational wave-emissions. A radiatively driven
supernova appears subsequently in response to high-energy continuum emissions produced
by the magnetic torus winds. When the envelope has expanded sufficiently to becoming
optically thin, X-ray line-emissions may appear conceivably accompanied by radio emissions.

13. To summarise
- Newborn Magnetars are interesting GW sources for Advanced
LIGO/Virgo-class instruments.
Newborn magnetars can be detectable from the
whole Virgo Cluster, where their birth rate is ~1 magnetar/yr
Short Gamma Ray Burst, if (for the most part) due to coalescing
binaries, provide an independent way of estimating the NS-NS and
NS-BH merging and GW detection rates
Evidence that the local Short GRB rate is dominated by NS-NS
and NS-BH binaries formed in globular clusters through
dynamical interactions: this increases the local rate and
chances of detecting GWs from these events

14. Kilonovae and Radio Flares EM signature similar to Supernovae
Significant mass ( mo) is dynamically ejected
during NS-NS NS-BH mergers
at sub-relativistic velocity ( c)
(Piran et al. 2013, MNRAS, 430; Rosswog et al , MNRAS, 430)
EM signature similar to Supernovae
Macronova – Kilonova
short lived IR-UV signal (days) powered by the radioactive decay of heavy
elements synthesized in the ejected outflow
Kulkarni 2005, astro-ph ;
Li & Paczynski 1998,ApJL, 507
Metzger et al. 2010, MNRAS, 406;
Piran et al. 2013, MNRAS, 430
RADIO REMNANT
long lasting radio signals (years)
produced by interaction of ejected
sub-relativistic outflow with surrounding matter
Piran et al. 2013, MNRAS, 430 12

15. Kilonovae Light Curves
Source at distance of 200 Mpc 5 10 15 20 25 30
Kilonova model afterglow peaks about
a day after the merger/GW event
NS-BH Piran et al.
NS-NS Piran et al.
Blackbody Metzger. et al.
Fe-Opacity Metzger et al.
Red magnitude
Major uncertainty OPACITY of “heavy r-process elements”
Days
Opacities:
Fe r-process
M/Mo=10-2
-20
-15
-10
- 5 5
1042
1041
1040
1039
Fe-Kilonova, β=0.1
r-process, β=0.1
New simulations including
lanthanides opacities show:
broader light curve
suppression of UV/O emission
and shift to infrared bands
Magnitude
Luminosity(ergs/s)
Days
Days
Barnes & Kasen 2013, ApJ, 775 13

16. The Advanced VIRGO/LIGO Era
Growing emphasis on the search for the astrophysical counterparts of candidate gravitational wave (GW) event
From astrophysically triggered searches to searches triggered by GW candidate events.
Astrophysical counterparts required to confirm nature of GW events 17

17. Advanced GWdetector era observing scenario
Position uncertainties
with areas of tens to hundreds of sq. degrees
Summary of plausible observing scenario
LSC & Virgo collaboration
arXiv:
aLIGO/Virgo Range
Rate
Localization 18 18 18

18. GRB970228: the 1st X-ray and Optical afterglow
Fast follow up with the BeppoSAX-NFIs (8hr) led to the discovery of a bright unknown X-ray source.
A second pointing 3 days after showed that source had faded.
(Costa, et al., 1997)
Accurate (~1 arcmin) X-ray position led to the identification of a fading optical source from ground based telescopes
(Pedichini et al 1997)
(Van Paradijs, et al., 1997)

19. High Energy Satellites:
* Wide field monitors (e.g. Swift), limited sensitivity
* X-ray optical design available (WFXT), but no approved program yet
- Optical/NIR: large field of view instruments needed
* Medium and Large telescopes have instruments < 1deg^2
* Few very small automated large field telescopes (~100 deg^2, R <10-12)
(Tortora, PiSky)
* Dawn of “Time Domain Astronomy”: PTF (1.2 m, 8 deg^2, R<21, 5d),
PanSTaRR (1.8 m, 9 deg^2, R< 22, 1 month)
* End of decade: LSST (8.4 m^2, 10 deg^2, R~24, ¼ sky twice/night)
Radio:
VLA, LOFAR, SKA
“Culture” of fast-response follow up observations: available especially in the SN and GRB communities. 20

20. Transient X-ray and radio sky is less populated than the optical sky
Optical transient sky
Kasliwal 2011, BASI, 39
Exploration of the optical transient sky at faint magnitudes and short timescale has started recently, but it is still unknown..
Optical contaminating transients:
foreground - asteroids, M-dwarf flares, CVs, Galactic variable stars
background - AGN, Supernovae
For rate see Rau et al. 2009, PASP, 121 and for fast transient (0.5 hr – 1d) see Berger et al. 2013, ApJ, 779
Transient X-ray and radio sky is less populated than the optical sky
X-ray contaminating transients:
tidal disruption events, AGN variability Ultra-luminous X-ray Source variability, background GRBs
Radio contaminating transients:
Supernovae, AGN variability
For rate see Mooley et al , ApJ,768
For rate in the Advanced LIGO/Virgo Horizon
see Kanner et al. 2013, ApJ, 774 27

21. PTF - Palomar Transient Factory
Other groups :
PTF - Palomar Transient Factory
Singer et al. 2013:
“We report the discovery of the optical afterglow of the γ-ray burst (GRB) A, identified upon searching 71 deg2 surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization.”
“The case of GRB A demonstrates for the first time that optical transients can be recovered from localization areas of ∼100 deg2, reaching a crucial milestone on the road to Advanced LIGO.”
8 deg
“The case of GRB A demonstrates for the first time that optical transients can be recovered from localization areas of ∼100 deg2, reaching a crucial milestone on the road to Advanced LIGO.”
“We report the discovery of the optical afterglow of the γ-ray burst (GRB) A, identified upon searching 71 deg2 surrounding the Fermi Gamma-ray Burst Monitor (GBM) localization.”
Detection limit: R ~ 20.5

22. INAF (Istituto Nazionale di Astrofisica) decided to participate in the EM follow-up program
as an Institution
by providing Italian observational resources
and the expertise in time domain astronomy

23. INAF- project: Gravitational Astrophysics
STEPS for an efficient EM-follow up
Reference Images
Observational strategy
Send data to Image Analysis Server
Wide-field telescope
FOV >1 sq.degree
VST
Image Analysis is performed by running specific pipelines.
The human intervention is not yet negligible.
Image Analysis Server “Fast” and “Smart” software
to select a sample of candidate counterparts
Spectra vs templates
Light Curves
Multi-wavelength analysis (Near-IR, Radio, hugh energy from space, ASTRI, CTA)
Candidate characterization
Time to react is very short so you have to be prepared and organised
VLT
LBT
The EM Counterpart of GW!

24. INAF- project: Gravitational Astrophysics
Advisory Board
P.I.: E. Brocato
Working Groups
WP 1
WP 2
WP 3
WP 4
WP 5
GW astronomy
Contact with LIGO / Virgo Collaboration
Search for EM candidates
Photometric software
Surveys, Ref. Images
Characterization
Spectroscopy
Light Curves
Multiwavelegthobservations
ToO proposals
Relationship EU partners
Space
Time Domain Astronomy
Swift
XMM
Chandra
Fermi
INTEGRAL
GW physical information
EM Observational strategies
Simulations
VLT
NTT
ESO telescopes
LBT
NOT / TNG (?)
REM
AZT-24 (NIR)
SRT (Radio)
VST
CITE
Asiago
TORTORA
Sicily (tbd)

25. INAF: WIDE-FOV telescopes to cover the GW error box
South America
VST m VLT Survey ESO telescope
 corrected FOV 1 deg x 1 deg, pixel scale of 0.21”/pixel
1 hour to cover a sky area of 40 sq. deg. in r’ band
reaching a magnitude of about 23
in 2016 the INAF-Guaranteed Time Observation
20% of the total observing VST time
Public Surveys: Reference Images available
REM (Rapid Eye Mount): 60 cm diameter fast robotic telescope
TORTORA camera (Telescopio Ottimizzato per la
Ricerca dei Transienti Ottici RApidi) FOV 24°x32°,
time resolution 0.1 s, B-limiting magnitude 11
 two cameras can observe simultaneously in optical and
NIR (J, H e K), FOV 10x10 arcmin

26. INAF: WIDE-FOV telescopes to cover the GW error box
Europe
“Campo Imperatore Transient Experiment”:
60cm Schmidt telescope with a 2 sq. deg. FOV up to
V ~21mag (project to extend to 6 sq. degree)
 near-IR telescope, AZT-24 FoV of 4.4’x4.4’ for characterization
Funds to realize a 1m Telescope (FOV 8 sq. deg) in Sicily
+ SMALLER FOV telescopes like Asiago, Loiano, IRAIT can help during the search and/or are useful for the characterization

27. INAF: Characterization of the EM counterparts candidates
Large Binocular Telescope (Arizona)
excellent for characterization,
INAF GTO+ToO (25 % INAF) .
North America
two 8.4 meter primary mirrors
collecting area equivalent to an
11.8-meter circular aperture
Optical/IR spectrographs
Large Binocular Camera, FOV 23'x23' , sampling of 0.23”/pixel
South America
Very Large Telescope (VLT, ESO)
four unit telescopes with main mirrors of 8.2m diameter
very useful X-shooter spectrograph covering a very wide range of wavelengths [UV to near infrared] simultaneously
INAF intends to coordinate collaborative ToO proposal
involving other European groups working in the field

28. INAF: Characterization of the EM counterparts candidates
TNG (Telescopio Nazionale Galileo)
 3.58m optical/infrared telescope
 currently optimally equipped for “exoplanet search”
its position could be crucial for the EM-follow up,
few possibilities to set up instruments for this program
Canarie
NOT (Nordic Optical Telescope 2.5 m) (+ Xshooter?)
good candidate for GW follow-up, thanks to its
good optics and versatile instruments: e.g.  
ALFOSC (Andalucia Faint Object Spectrograph and Camera) 
GTO (fraction) + proposal for ToO

29. INAF: Radio facilities INAF: Space high-energy facilities
INAF radio antennas:
 Medicina (30 m parabolic antenna)
Noto (32 m parabolic antenna)
Sardinia Radio Telescope (64 m)
SMALL FOV  characterization
INAF: Space high-energy facilities
From space, INAF can guarantee access - through submission of regular or DDT proposal starting from
coordinated initiatives of the INAF scientists -  to Swift, XMM, Chandra, Fermi, INTEGRAL.
INAF: Archival search
LBT + VST image archives
ASDC Archive of space missions + ESO data archive

30. INAF- project: Gravitational Astrophysics
Large FoV (1x1 d)+ mag limits (< 23 m) + High resol. (0.2 p/”)
Characterization: up to 8m class telescopes
Site: southern and northern hemisphere
Wide wavelength coverage: ground based facilities from optical to radio + high-energy space facilities
Know-how: Time Domain Astronomy, Observational Strategy, Image analysis, Accurate Photometry in crowded fields, GRB astronomy, Data Interpretation, Theoretical models
Collaboration with Virgo teams is crucial
To remain in touch:
Collaboration with Virgo teams is crucial

31. VESF – Virgo EGO Science Forum
The scope of VESF is promoting the physics of gravitational
waves, and the collaborations among groups in different
countries
The Forum is intended to be open to scientists in the field of astrophysics,
astroparticle, general relativity, gravitation etc, that may be interested in
the data expected from Virgo and its future upgrades.
VESF presently comprises:
34 groups, 182 members from Virgo, 149 non-Virgo
belonging to European universities, laboratories and astronomical observatories.
It is a composite and lively community, developing different issues relevant to the theory and modeling of gravitational wave sources and to the data analysis.

32. VESF Executive Board. The executive board is presently composed by
- the EGO director (Federico Ferrini)
the Virgo spokesperson (Jean-Ives Vinet)
and four members elected by the VESF Council for a period of two years, to represent the following research areas
General Relativity (Nikolaos Stergioulas)
Theoretical Astrophysics and Cosmology (Toni Font)
Observational Astrophysics (Andrea Possenti)
Experimentation in fields related to GW detection not participating to Virgo (Guglielmo Tino)
The EB elected the VESF Coordinator, choosing in a pool of candidates
proposed by the VESF community (Luigi Stella)
Jan 2014 VESF EB Meeting: proposal of revised VESF Charter sent to VSC
the council is composed of the representatives of each group, The number of
representatives is equal to the number of persons belonging to the group divided by six
plus one.