MAGIC observations of VHE gamma rays from the flaring blazar TXS coincident with high-energy neutrino IceCube A

Transcription

1 MAGIC observations of VHE gamma rays from the flaring blazar TXS coincident with high-energy neutrino IceCube A Elisa Bernardini,, Abelardo Moralejo, Michele Peresano, Elisa Prandini, Konstancja Satalecka, for the MAGIC collaboration TeVPA18, Berlin August 29th, 2018

2 Overview EHE A follow-up observations MAGIC detection of TXS MAGIC deep exposure and results Discussion and conclusions (Interpretation see Elisa Bernardini s talk for further details) The IceCube Collaboration et al., Science 361, 146 (2018) arxiv:

3 Overview EHE A follow-up observations MAGIC detection of TXS MAGIC deep exposure and results Discussion and conclusions (Interpretation see Elisa Bernardini s talk for further details) The IceCube Collaboration et al., Science 361, 146 (2018) arxiv: See also talks by: K. Satalecka+ E. Bernardini+A. Franckowiak++ The MAGIC Collaboration, ApJL 863, L10 (2018) arxiv:

4 EHE A follow-up observations: the MAGIC history 4

5 EHE A - Neutrino alert September 22nd Since September 24th September 27th ////////////////////////////////////// Better energy and direction reconstruction followed Fermi-LAT Collaboration followed-up the EHE A error circle ATEL TITLE: GCN/AMON NOTICE NOTICE_DATE: Fri 22 Sep 17 20:55:13 UT NOTICE_TYPE: AMON ICECUBE EHE [ ] SRC_RA: d {+05h 09m 08s} SRC_DEC: d {+05d 45' 06"} [ ] SRC_ERROR: [arcmin radius, stat+sys, 50% containment] [ ] DISCOVERY_TIME:...{20:54:30.43} UT N_EVENTS: 1 [number of neutrinos] [ ] ENERGY : e+02 [TeV] SIGNALNESS: e-01 [dn] CHARGE: [pe] [ ] ////////////////////////////////////// They found that TXS was showing brightening in the GeV band : all data used : weather cuts used Flare detected by MAGIC in VHE γ rays Hard spectrum in HE band ask for triggering VHE observations Flare detected by Fermi-LAT in HE γ rays 5

6 EHE A - Neutrino alert 6

7 MAGIC detection of TXS

8 MAGIC detection of TXS TS 12.9h between September 24th and October 4th Signal 6.2 sigma Firm detection 8

9 The blazar TXS TXS shows a synchrotron peak around 1014 Hz classified as LBL/IBL VHE The IceCube Collaboration et al., Science 361, 146 (2018) arxiv: VHE gamma-ray observations allowed computation of redshift upper limits with E. Prandini s method between 0.61 and 0.98 at 95% CL depending on EBL model used z = ± Paiano et al. 2018, ApJL 854, 2 arxiv:

10 MAGIC deep exposure 10

11 TXS deep exposure 41 hours of good-weather observations between September 24th and November 2nd Day-timescale variability detected Probability of constant flux < 0.3% 2 flares detected (Oct 3rd-4th and Oct 31st) Lower state detected (where F(E > 90 GeV) < cm 2 s 1) The MAGIC Collaboration, ApJL 863, L10 (2018) arxiv:

12 TXS deep exposure 41 hours of good-weather observations between September 24th and November 2nd Day-timescale variability detected Probability of constant flux < 0.3% 2 flares detected (Oct 3rd-4th and Oct 31st) Lower state detected (where F(E > 90 GeV) < cm 2 s 1) Flare 1 Flare 2 LS 12

13 TXS deep exposure Differential photon spectrum between 80 GeV to 400 GeV Modelled by simple power law with a spectral index ranging from -4.0 ± 0.3 to -3.5 ± 0.4 Significantly steeper than Fermi-LAT quasi-simultaneous spectrum No spectral variability Interpretation of observational results with onezone lepto-hadronic model see E. Bernardini s talk 13

14 Discussion and conclusions 14

15 Discussion Several questions arising after TXS detection TXS is the likely counterpart of the IceCube EHE A neutrino event a new multi-messenger correlation? Detected at VHE by MAGIC (one of the few VHE-detected IBLs) important info for modelers Can neutrinos be produced efficiently by BL Lac objects? MWL SED appears predominantly leptonic: potential hadronic contributions? Evidence of proton acceleration: can it be a source of UHECRs? Constraints from MWL SED including VHE 15

16 Conclusions Very exciting results! Source variable in VHE γ rays First detection of HE and VHE γ-ray emission in coincidence with neutrino alert! Theoretical interpretation suggesting probable origins of UHECRs see Elisa Bernardini s talk for further details on MAGIC results Thank you! 16