Pietro Ubertini, IAPS-INAF on behalf of the INTEGRAL Gravitational Team

INTEGRAL GW Team members: A. Bazzano, E. Bozzo, S. Brandt, J. Chenevez, T. J.-L. Courvoisier, R. Diehl, A. Domingo, C. Ferrigno, L. Hanlon, E. Kuulkers, E. Jourdain, A. von Kienlin, P. Laurent, F. Lebrun, A. Lutovinov, A. Martin-Carrillo, S. Mereghetti, L. Natalucci, J. Rodi, J.-P. Roques, V. Savchenko, R. Sunyaev, and P. Ubertini, Et al….

P. Ubertini, IAPS-INAF

A DECADE OF AGILE: RESULTS, CHALLENGES AND PROSPECTS OF GAMMA - RAY ASTROPHYSICS December 11-13, 2017; Accademia dei Lincei, Palazzina Auditorium, Roma

INTEGRAL rivela raggi Gamma da due stelle di neutroni collassate

P. Ubertini

INTEGRAL ESA M2 mission of the

Horizon 2000 program, launched 2002

INTEGRAL main features: (Key for GW prompt and afterglow science) 3 keV-10 MeV energy range with unprecedented sensitivity Wide FoV: ≈ 100-1000 deg2 plus.. All-sky monitor capability in the range 80 keV - 2.5 MeV High time resolution: <120 μs absolute Arc min angular and keV energy resolution and Unique polarimetry capabity Very elliptical orbit with duty cycle >85% and all-sky coverage Long uninterrupted observations 2.7days 6 h perigee passage INTEGRAL is the link between the soft X-ray and high energy γ-ray

In fact, INTEGRAL has observed 5 out of 6 BH-BH mergers

LIGO-VIRGO detection INTEGRAL Observation GW150914 Savchenko et al., ApJL, 820, 2, L36, 2016, Abbot et al., ApJL, 826, L13, 2016 Abbot et al., ApJS., 225, 8A, 2016 LVT151012 Savchenko et al., A&A, 603, A46, 2017 GW151226 Missed, pergee passage GW170104 Savchenko et al., ApJL, 2017 GW170814 Savchenko et al., GCN GW170817 NS-NS Inspiral Savchenko et al., ApJL 848, L15, 2017, Abbott et al., ApJL 848, L12, 2017 Abbott et al., ApJL 848, L13, 2017

P. Ubertini, IAPS-INAF Credits: LIGO-VIRGO Collaboration

However , one of the main expected source

of GW is the inspiral of binary NS:

GW170817 = GRB170817A

is the text book case!!

Small BH, or Massive NS (EoS still realistic?), New physics object?.....

Before GW 170817 there were 2 missing informations: a signal in gamma-ray contemporary to the LVC trigger and an accurate error box: INTEGRAL and FERMI have detected for the first time a quasi- simultaneous GRB and improved in real time the error box

INTEGRAL Sensitivity to GW170817 direction

GRB FERMI-INTEGRAL error box

Zona di emissione della GW LIGO/VIRGO

Zona di cielo da cui vengono i segnali combinati LVC-FERMI-INTEGRAL

P. Ubertini, IAPS-INAF Credits: B.P. Abbot et al., ApJL, 2017, in press; Savchenko et al., ApJL, 2017, in press

INTEGRAL detects prompt gamma ray emission quasi-contemporary to GWs

Savchenko et al., A&A, 603, A46, 2017 Part of the error box was observed by All-sky detectors and part was in the FoV of the gamma-ray telescopes

INTEGRAL

Direzione di arrivo del segnale Gravitazionale (GW)

dalle due stelle di neutroni che si fondono (NS-NS)

Arrival sequence of the Signals: • Virgo (Pisa) • FERMI LEO • Geo Centre • LIGO Livingston • LIGO Hartford • INTEGRAL HEO

FERMI-GBM

P. Ubertini, IAPS-INAF

P. Ubertini

NOTICE and GCN sequences

• On 2017-08-17 at 12:41:04.47 UTC a signal consistent with the merger of a BNS was detected by the LIGO-Hanford detector

• The subsequent alert was issued in response to a public real-time Fermi/GBM trigger on a sGRB at 12:41:06.48 UTC

• FERMI/GBM trigger, GCN 21505, issued 2017-08-17 at 13:21:42 GMT

• INTEGRAL detection, GCN 21507, of prompt γ-ray counterpart to LIGO VIRGO G298048, coincident with GBM trigger, issued at 2017-08-17 at 13:57:47 GMT

• LIGO/VIRGO identification of a binary neutron star candidate coincident with GBM trigger issued at 14:09:25 GMT: GW170817

INTEGRAL has detected a short GRB 1.7s after the NS-NS coalescence: this has been the first detection of the Kilonova resulted from the debris of the NS-NS fusion…. Just after the SGRB detection we have failed to detect any gamma ray afterglow, with the best sensitivity to the continuum and gamma-ray lines

NS-NS inspiral 120 My ago GW detected by LIGO-VIRGO T=0

NS-NS inspiral GW detected by LIGO-VIRGO T=0 Kilonova produced and sGRB emitted T=1.7s after the GW front

V. Savchenko et al. 2017 ApJL 848 L15 B. P. Abbott et al. 2017 ApJL 848 L13

INTEGRAL spent about 20ks in with the same aspect after the prompt detection, then was Repointed toward the most probable error-box (known at that time) and then toward the refined error box position for about 5 days

Allsky momitoring SPI-ACS + IBIS-PICsIT + IBIS-VETO

Pointed observations SPI + IBIS + JemX +OMC

Possible models published on 16 October, obtained from the prompt Short GRB seen by INTEGRAL and FERMI/GBM,

This were the best models available At the 30 November GSSI meeting

Figure 2. Schematic illustration of the various possible jet and dynamical ejecta scenarios. A) A jet seen on-axis, generating both the low-luminosity gamma-rays and the observed radio afterglow. This scenario cannot explain the late rise of the radio emission. It is also unable to explain11 how a low-luminosity jet penetrates the ejecta. It is therefore ruled out. B) A regular (luminous) SGRB jet seen off-axis, producing the gamma-rays and the radio. The continuous moderate rise in the radio light curve rules out this scenario. C) A choked jet giving rise to a mildly relativistic (ɣ~2-3) cocoon which generates the gamma-rays and the radio waves via an on-axis emission. This is the model that is most consistent with the data. It accounts for the observed gamma-rays, X-rays (possibly also ultraviolet and optical) and radio emission, and provides a natural explanation to the lack of an off-axis jet signature in the radio. D) A successful jet that drives a cocoon and remains hidden. The cocoon generates the gamma-rays and the radio emission, and outshines the jet at all wavelengths. This scenario is less likely based on theoretical considerations, which suggest that the jet and the cocoon should have comparable energies, in which case the jet signature would have been observed in the radio band. E) The fast velocity tail of the ejecta (β~0.8-0.6c) produces the radio emission. In this case, the jet must be choked (otherwise its off-axis emission should have been seen). While the radio emission is fully consistent with this scenario, the energy deposited in faster ejecta (ɣ~2-3) must be very low. It is unclear then what is the source of the observed gamma-rays.

A mildly relativistic wide-angle outflow in the neutron star merger GW170817 K. P. Mooley (1,2,3), E. Nakar (4), K. Hotokezaka (5), G. Hallinan (3), A. Corsi (6), D.A et al.

arXiv:1711.11573, 30 November 2017 Last week!

Current Work

• Common search of sub-threshold Ligo-Virgo signals coincident with INTEGRAL sGRBs • Search for past INTEGRAL/PICsIT GRBs previously

reported by other instruments, focus on short GRBs

• Spectral analysis of soft gamma-ray spectrum above ~300 keV to extend Fermi/GBM results

• Search of INTEGRAL/PICsIT and SPI/ACS data for faint SGRBs below trigger threshold

SGRBs seen by INTEGRAL & Fermi/GBM GRB170817a: The accurate measurement of the arrival time of GRB from INTEGRAL, AGILE,

FERMI, SWIFT, etc allow an accurate determination of the arrival direction of GW

• Develop Real-Time analysis to search for and report bursts immediate web alert (?)

• Modify current on-board software to transmit PICsIT data in photo-by-photon mode during slews for better energy resolution – No data currently transmitted during slews

– Standard data in 8 broad energy channels with 16ms time resolution

Current Work

Summary INTEGRAL followed-up full GW localization region 5 out of 6 reported events, as expected with 85% duty cycle. Combination of the high duty cycle and high sensitivity is unique, and allowed us to contribute to the first joint GRB-GW Detection Detection of a GRB from an off-axis merger implies much more frequent GRB-BNS associations, which might happen regularly in O3, the bright triggers will be most probably immediately public Early GRB-GW detection: be prepared for unexpected optimistic scenario! Multimessenger observations open possibilities for studying processes in energetic events involving compact objects, implications that go beyond BNS mergers. Neutrino follow-ups remain very promising and tentative MM detections might soon reach the level of solid evidence

Ed Van Den Heuvel COMMENT NATURE sulla possibilita’ di osservare controparti elettromagnetiche in raggi gamma di Onde Gravitazionali dallo spazio: INTEGRAL

4 April 17 August …

Stay tuned!!

Thanks for your attention!

INTEGRL SPI-ACS

THANKS FOR YOUR

ATTENTION.. &..

STAY TUNED!!

INTEGRAL observations of GW150914

10-6 - ratio of energy in 75-2000 keV to GW energy

5

A milestone observation, also establishing an example of INTEGRAL capabilities, SPI-ACS

in this case, similar limits were obtained for LVT151012, GW170104, GW170814

VS 2016

Savchenko et al., ApJL, 820, 2, L36, 2016

The INTEGRAL GW Team meet 2 days ago and discussed the possibility to maintain on some of the all-sky detectors to increase the coverage from 85% to 90-95% ?

P. Ubertini

• La rivelazione contemporanea di Onde Gravitazionali e raggi Gamma da parte di LIGO-VIRGO, INTEGRAL e FERMI ha anche permesso per la prima volta di fare una misura accuratissima della velocita’ di propagazione delle onde gravitazionali. Infatti la differenza di tempo di arrivo tra i due segnali e’ di soli 1.74 secondi, dopo un viaggio durato circa 100 milioni di anni: quando i due segnali erano a circa meta’ percorso verso la terra si estinguevano i dinosauri!

• La differenza tra la velocita’ delle GW e della luce e’ tra −3 × 10−15

and +7 × 10−16 volte quella della luce.

• Queste misure hanno una rilevanza storica anche nel campo della fisica fondamentale e della fisica quantistica.

P. Ubertini, IAPS-INAF

INTEGRAL rivela raggi Gamma da due stelle di neutroni collassate

P. Ubertini, IAPS-INAF Credits: B.P. Abbot et al., ApJL, 2017, in press; Savchenko et al., ApJL, 2017, in press

La rivelazione multimessenger del segnale gravitazionale GW170817 e del GRB 170817A. Primo e secondo pannello dall’alto: segnale di FERMI GBM, banda di energia 10 - 50 keV e 50 - 300 keV Terzo pannello: segnale di INTEGRAL/SPI-ACS, banda di energia da 100 keV a 80 MeV. Pannello in basso: mappa delle frequenze registrate da LIGO-Hanford and LIGO-Livingston.

INTEGRAL rivela raggi Gamma da due stelle di neutroni collassate

P. Ubertini

INTEGRAL: ESA International Gamma Ray Observatory 15 years of scientific success Heading 2020

INTEGRAL main features: 3 keV-10 MeV energy range with unprecedented sensitivity Wide FoV:≈ 100-1000 deg2 plus.. Allsky monitor capability in the range 80 keV - 2.5 MeV High time resolution <120 μs absolute Arc min angular accuracy and keV energy resolution Unique polarimetry capabity Long uninterrupted observations 2.7days, 6 h perigee passage Real-Time GRB transmission to ground and web delivery

INTEGRAL is the link between soft X-ray and high energy γ-ray science

So far 1000 INTEGRAL papers published

102+7 on-going PhD thesis (15+1 Italy)

and 100+ press release

2/10/’17

15 YEARS

IN ORBIT

P. Ubertini, IAPS-INAF

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P. Ubertini

• La misura di INTEGRAL ha caratterizzato in modo completamente diverso le GW registrate precedentemente dimostrando, per la prima volta, la presenza di un segnale in raggi gamma, emesso dalla collisione di 2 stelle di neutroni.

• INTEGRAL ha individuato con precisione, insieme al satellite FERMI della NASA, la zona del cielo da cui venivano i segnali e permesso di puntare verso la direzione di arrivo osservatori Radio, Ottici e di Raggi-X, solo 11 ore dopo la scoperta dei raggi Gamma, e che hanno identificato la galassia da cui arrivavano i segnali rivelati.

P. Ubertini, IAPS-INAF

INTEGRAL rivela raggi Gamma da due stelle di neutroni collassate