imulating gravitation and cosmolog! in condensed matter and optical s!stems " #$% 2&/'(/2'1) Black-hole superradiance: probing the dark universe with compact objects and GWs *+bsolete,) overview: Brito. $ardoso. /ani. 0Superradiance1 " pringer 2ect. 4otes /h!s3 )'6 *2'15- - 1501.06570 Paolo Pani Sapienza University of Rome & INFN Roma1 https://web.uniroma1.it/#mun% http://www.DarkGRA.or#1/26 Average train delay yesterday in Italy: 3-4 hr 2/26 Outline /rimordial Black-holeBlack (B6) holessuperradiance: a primer black holes B6 superradiant instability triggered b! ultralight bosons & GW signatures Superradiance in stars and pulsar-timing constraints on dark photons Superradiance triggered by plasma: constraints on spinning primordial B6s P. Pani - Black-hole superradiance @ ECT Trento 2019 &/26 What’s superradiance? ;n ph!sics. superradiance is a radiation enhancement effect in several conte=ts including<>uantum mechanics. astroph!sics<and relativit!3 ?cit3 Wikipedia] P. Pani - Black-hole superradiance @ ECT Trento 2019 8/26 BH superradiance Leldovich. Press. %eukolsky *1)('s- Superradiant scattering off a Kerr ! when Thorne. Price. GacdonaldHs 0Gembrane /aradigm” *1)I6- Bequires dissi"ation → event horizon BichartDJ. Ph!s3Bev3 KI' *2'')- 128'16 Brito. Cardoso. //. 0 uperradiance1 pringer *2'15- EmpliFcation depends on the nat#re of the %osonic &eld P. Pani - Black-hole superradiance @ ECT Trento 2019 5/26 uperradiant scattering off a B6 scattering amplification factors 2arger amplification for GWs (S=2) and at high spin 4onlinear effects (slightl!- decrease efficiency ?East. BamaDanoPlu. /retorius /BK I) '615'& *2'18-@ mall effect, e.g. luminosity modulation in binary pulsars ?Bosa. /2B 2'15 7 /BK *2'1(-@ P. Pani - Black-hole superradiance @ ECT Trento 2019 6/26 uperradiance in the lab %orresJ. 4ature Physics 1&. I&&-I&6 *2'1(-. see 'il(e Wein$urtner*s tal( www.gravitylaborator!.com P. Pani - Black-hole superradiance @ ECT Trento 2019 (/26 BH superradiant instabilit! Kamour. Keruelle 7 BuOniQ /ress-%eukolsk!. KetweilerQ Louros 7 Eardley 1)I'sQR. hlapentokh-Bothman. 2'15 Superradiant scattering + Yukawa effective potential Spinning B6s are unstable against massive bosons +ast , -retori#s, -/0 12017) B6 energy/spin extraction → condensate $oupling parameter P. Pani - Black-hole superradiance @ ECT Trento 2019 I/26 Ultralight Felds in the dark universe? $ompelling dark-matter candidates alternative to W;G/s -22 Uuzzy DG: mass ~ 10 eW → no problems at sub-kpc scale 6ui. +striker. %remaine. Witten. /BK)5 '8&581 *2'1(- /lethora of sub-eW DG particles: X$K axion, stringy axion-like particles (A2/s), axiverse ErvanitakiJ. /BKI1 12&5&' *2'1'- Kark photons & hidden sectors, massive gravitons … $ommon properties: Bosonic fields -&& Small mass (from sub-eW down to 10 eW- Weakly coupled to SG (or not coupled at all,- P. Pani - Black-hole superradiance @ ECT Trento 2019 )/26 Dark sectors and ultralight particles #ssigJ. 1&113''2). 6uiJ. /BK 2'1(. ;rastorDa 7 BedondoJ 2'1I E=ion-like particles *E2/s- Kark photons CardosoJ. Y$EP 2'1I $ourtes! of J. Redondo earches Mor ultralight DM with strong gravit! P. Pani - Black-hole superradiance @ ECT Trento 2019 1'/26 BH superradiant instability spectrum ;nstability depends on spin of the B6 & particle spin (S): ;ncomplete timeline of (relatively) recent developments on the spectrum: Scalar. numerical spectrum ?Kolan /BK 2''(@ Wector. nonspinning case ?Bosa 7 Kolan /BK 2'12@ Wector. >uadratic in spin ?/aniJ /B2 2'12@ Scalar/vector. time-domain, an! spin ?WitekJ /BK 2'1&@ %ensor. linear in spin ?Brito. $ardoso. /ani /BK 2'1&@ #U% approach ?#ndlich 7 /enco. Y6#/ 2'1(@ Wector. 4ewtonian appro=imation ?Bar!akhtarJ /BK 2'1(@ Wector. fre>uenc! domain, /K#s. an! spin ?CardosoJ Y$E/ 2'1I@ Wector. separabilit!. an! spin ?UrolovJ /B2 2'1I@ Wector. numerical spectrum ?Kolan /BK 2'1I@ P. Pani - Black-hole superradiance @ ECT Trento 2019 11/26 #volution of the instabilit! 4irst nonlinear sim#lation: East , Pretori#s. -/L 2017 superradiant instabilit! GW emission GWs Separation of scales → adiabatic appro=. linearized analysis GW emission → quadrupole fails $an be also studied in terms of transition probabilities & occupation numbers ErvanitakiJ 2'18-2'16 %wo generic predictions: B6s should N+% spin fast in the presence of ultralight bosons /eriodic GW signal → continuous sources for L;GO/Virgo/L; E P. Pani - Black-hole superradiance @ ECT Trento 2019 12/26 5ote: → realfields Uor is negligible→ Backreaction $ondensate Engular momentum for complex field → forcomplex Evolution of the instabilit! the of Evolution quasi-stationary B6s quasi-stationary B6s P. Pani - Black-hole superradiance @ ECT Trento 2019 Trento ECT @ superradiance - Black-hole PaniP. Kerr B6s with scalarhair with B6s Kerr Zerr metric Zerr 6erdeiro 7 Badu 2'18-2'1I 7 6erdeiro Badu Brito. Cardoso. //. 2'15 Class3 Xuantum Grav. &2 1&8''1 Grav. 2'15 Class3 Xuantum //. Cardoso. Brito. Energ! densit! oM the cloud the oM densit! Energ! 1& /26 Bounds on light bosons #=cluded regions GW15')18 [-ra! data X$K a=ion E=ion-like particles String a=iverse Kark photons Girror KG Gassive photon Gassive spin-2 Gassive graviton stellar intermediate supermassive Generic prediction: 0gaps1 in the B6 “Regge plane1 ErvanitakiJ. /h!s3Bev3 KI& *2'11- '88'26 P. Pani - Black-hole superradiance @ ECT Trento 2019 18/26 ;mpact of multiple modes Small seed 2arge seed Uicarra. /ani. Witek. /BK 2'1) 1 mode 2 modes #volution depends on energ! of initial seed: Xuantum fluctuation → multiple modes negligible 2arge seed → impact of initial amplitude Gight be relevant for B6s formed from mergers Xuasi-adiabatic evolution agrees well with numerical simulations ?+kawaJ 2'1I@ P. Pani - Black-hole superradiance @ ECT Trento 2019 15/26 ErvanitakiJ 2'18-2'16 Bar!akhtar+ 2'1( GW signatures Brito+ 2'1( $ontinuous GW source at a frequency given by the axion mass BritoJ. /B2 2'1(. /BK 2'1( 0I'A 0I6789irgo :+CI67 %owards multiband GW constraints on ultralight fields P. Pani - Black-hole superradiance @ ECT Trento 2019 16/26 ErvanitakiJ 2'18-2'16 Bar!akhtar+ 2'1( GW direct detection Brito+ 2'1( 2; E *mass-spin- /ipeline in L;G+/Virgo ?K9Entonio 2'1I. ;siJ 2'1I@ P. Pani - Black-hole superradiance @ ECT Trento 2019 1(/26 BH mass-spin distribution ErvanitakiJ 2'18-2'16. Bar!akhtarJ 2'1(. BritoJ 2'1(. CardosoJ 2'1I 2; E will Fll the mass gap by detecting intermediate-mass B6s tronger constraints for dark photons and massive spin-2 Felds P. Pani - Black-hole superradiance @ ECT Trento 2019 1I/26 Uollow-up searches ErvanitakiJ 2'18-2'16. Bar!akhtar+ 2'1(. Ghosh+ 2'1I 0Exion1 counterpart for 2;GO/Wirgo P. Pani - Black-hole superradiance @ ECT Trento 2019 1)/26 tochastic background from axions BritoJ /B2. /BK 2'1( Uormation rate density Energ! spectrum per comoving volume $an affect direct detection Kirect bounds from L;GO O1 Ectual searches ?%sukadaJ. 1I123')622@ P. Pani - Black-hole superradiance @ ECT Trento 2019 2'/26 /robing superradiance in binaries Baumann+ /BK 2'1). 6annukselaJ 4ature Estron3 2'1) Resonant excitation of levels. depletion of the cloud #GB;s can probe the cloud mass function ?GacedoJ EpY 2'1&. 6annukselaJ 4at3 Estron3 2'1)@ P. Pani - Black-hole superradiance @ ECT Trento 2019 21/26 Coupling to photons BosaJ /B2 2'1I. Ikeda+ /B2 2'1). BoskovicJ /BK 2'1) Exion stimulated deca! to photon even in flat space Blasts of light from Kerr B6s iM Gillisecond radio burst from axions and primordial B6s ?BosaJ /B2 2'1I@ P. Pani - Black-hole superradiance @ ECT Trento 2019 22/26 Superradiant instabilities in stars $ardoso. /ani. Su. /BK 2'1( #lectrical conductivit! replaces the horiDon conductivit! uperradiant scattering of #G waves ;nstabilit! for dark photons P. Pani - Black-hole superradiance @ ECT Trento 2019 2&/26 Superradiant instabilities in stars $ardoso. /ani. Su. /BK 2'1( uperradiant-instabilit! time scale Geasured for several pulsars /ulsar-timing measurements of spin and spin-down rates put direct constraint on dark-photon models P. Pani - Black-hole superradiance @ ECT Trento 2019 28/26 Primordial BH bombs // & 2oeb. /h!s3Bev3 KII *2'1&- '81&'1 /lasma frequency Superradiant instability at different redshift Also investigated in the conte=t of Uast Badio Bursts $onlon 7 6erdeiro. /2B *2'1I- P. Pani - Black-hole superradiance @ ECT Trento 2019 25/26 /rimordial BH bombs // 7 2oeb. /h!s3Bev3 KII *2'1&- '81&'1 D ^ 1'& D ] 1'6 C thermalization ● )5_ confidence-level bounds due to μ and y CGB distortions Bounds depend linearl! on the /B6 spin *should be small ?6aradaJ 2'1(. Girbaba!iJ 2'1). Ke 2ucaJ 2'1)@- P. Pani - Black-hole superradiance @ ECT Trento 2019 26/26 $onclusion & Open ;ssues Smoking guns from B6 superradiant instabilities Gaps in the B6 Begge plane → highl!-spinning BHs disfavored /eriodic GW sources → detecting ultralight bosonic KG with 2;G+/Virgo? /ulsar-timing constraints on superradiant instabilities in neutron stars Bounds on spinning /B6s $ardoso-/ani. $#B4 $ourier 2017 +pen problems: Gassive spin-2, plasma, nonlinear coupling, effects in binaries, … P. Pani - Black-hole superradiance @ ECT Trento 2019 2(/26 Backup slides “Nothing is More Necessary than the Unnecessary” [cit.] P. Pani - Black-hole superradiance @ ECT Trento 2019 2I/26 Gaps in the BH “Regge plane” Generic prediction: 0gaps1 in the B6 0Regge plane1 ErvanitakiJ. /hys3Bev. KI& *2'11- '88'26 P. Pani - Black-hole superradiance @ ECT Trento 2019 2)/26 Evolution of BH-axion condensates Brito. Cardoso. //. 2'15 $lass3 Xuantum Grav3 &2 1&8''1 Soshino 7 Zodama. /%#P 2'18 *2'18- '8&#'2 Barausse. Cardoso. //. Phys3Bev. KI) *2'18- 1'8'5) P. Pani - Black-hole superradiance @ ECT Trento 2019 &'/26 Hidden conductivit! Mass basis Hidden conductivity P. Pani - Black-hole superradiance @ ECT Trento 2019 &1/26 Evolution of the SR instabilit! superradiant instability GW emission GWs P.