1. Astrophysics: 2016 highlights and the way forward
(My objective view in 10min) Eli Waxman Weizmann Institute of Science
Eli Waxman | Weizmann Institute of Science

2. Eli Waxman | Weizmann Institute of Science

3. Gravitational Waves: Generation and detection
Electro-Magnetic Transmitter Receiver
Accelerating electric EM Wave Accelerating electric
charge (dipole) charge
Gravitational “Transmitter” Gravitational Antenna
Accelerating mass GW Accelerating mass
(quadrapole) e- e- m
Eli Waxman | Weizmann Institute of Science

4. The challenge: Signal strength
GW’s are a Fundamental prediction of General Relativity, 1916
Large masses, 2 x 10 Msun,
with extreme acceleration- nearly “touching” black holes
freely “floating”
test masses
𝑫~𝟏 Giga light years
𝒅~ 𝑹 𝑺 = 𝟐𝑮𝑴 𝒄 𝟐 =𝟑𝟎km,
𝐯~𝐜,
𝒇 𝑮𝑾 ~ 𝒄 𝟐𝝅 𝑹 𝑺 =𝟏 kHz, 𝒅𝑳 𝑳 =𝒉="𝒔𝒕𝒓𝒂𝒊𝒏"
𝑷 𝑮𝑾 ~𝟏 𝟎 𝟐𝟐 𝑷 Sun ~𝟏 𝟎 𝟏𝟏 𝑷 Galaxy > 𝑷 (Obs.) Universe . 𝒉~ 𝑹 𝑺 𝑫 ~𝟏 𝟎 −𝟐𝟏 d m L
L+dL m
Eli Waxman | Weizmann Institute of Science

5. Meeting the challenge: LIGO
m, mirror L
Laser light
L+dL
m, mirror
Change in
Escaping Light phase
(Michelson interferometer)
Eli Waxman | Weizmann Institute of Science

6. First direct detection of Gravitational Waves
A merger of
2x 30 solar mass black holes
(derived from 𝒇 𝑮𝑾 )
Distance ~ 1 Giga light years (from 𝒉).
Location on the sky poorly known
Host galaxy unknown
Exact distance unknown
Difficult to search for EM “afterglow”
Eli Waxman | Weizmann Institute of Science

7. What did we learn? GW exist as predicted by GR.
We already knew, indirectly
from the Hulse-Taylor binary
neutron star.
30 solar mass black holes exist.
Stellar evolution allows the formation of “tight” black hole binaries.
𝑀=1.4 𝑀 Sun
𝑅 ~ 10 km
𝑑= km
𝑀=30 𝑀 Sun
𝑅 ~ 100 km
𝑑 ~ 100 km
Eli Waxman | Weizmann Institute of Science

8. What Next? More black hole binaries, BH formation & evolution.
Neutron star mergers
More black hole binaries,
BH formation & evolution.
Improved LIGO +
Virgo, LIGO-India, KAGRA:
Detection of neutron star mergers,
~(10 deg x 10 deg) error boxes
(~2020).
Detection of EM afterglows- crucial:
Identify host galaxy,
Determine exact distance,
Matter properties at extreme densities,
Production of heavy elements (Au, Pt).
Radio to gamma-ray “Afterglow”
Eli Waxman | Weizmann Institute of Science

9. ULTRASAT UV Transient Astronomy Satellite
Will revolutionize our understanding
of the transient UV universe.
EM follow-ups of GW
X-rays: rare, 1:100 (jet aiming at us).
Radio: ~1yr delay, requires CSM.
IR: challenging (wide field inst.).
Optical: more difficult than UV.
ULTRASAT UV follow-up of GW
Instantaneous >50% of sky
(8 times better than ground based),
in <5 min for >2.5hr.
GW error box in a single image.
Sensitive to predicted UV.
Field of View
210 deg2
Band nm
Limiting mag
21.9 (5s, 900s)
Eli Waxman | Weizmann Institute of Science
Target of Opportunity access

10. Multi-messenger and transient astronomy
Astronomy with messengers other than photons:
Gravitational waves, Neutrinos.
Focus on transient (explosive) events.
Driven by fundamental physics and astrophysics questions:
The nature of gravity, the origin of neutrino masses…
Formation and evolutions of BHs and NSs, explosion mechanisms of stars, production of heavy elements…
Enabled by technology advances:
GW, neutrinos,
Wide field telescopes, fast follow-up capabilities.
Eli Waxman | Weizmann Institute of Science