Present and past activity at the Galactic center - Gabriele Ponti INAF OA Brera - MPE - INAF OAS
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AGN - Starbursts influence CGM AGN Starburst M 82: Hubble/Spitzer/Chandra Outstanding progress ➜ Understand feedback between nuclear activity and CGM MS 0735.6+7421: Chandra/Hubble/VLA
Do galaxies influence their CGM? Quiescent galaxy Does the nuclear activity of quiescent galaxies influence their CGM? ➜ Let’s look to the Milky Way M83: Subaru/ESO/Hubble
The structure of the Milky Way Galactic bar mass Mass ~ 7×109 MSun Size ~ 3 kpc Binney +91; Bally +10; Ridley +17 From Spitzer/GLIMPSE data Churchwell +09
The central degrees of the Milky Way Molinari+11 Central Molecular Zone Herschel column density map Sgr A* 140 pc 1 deg Molinari+11 Abundant gas reservoir ~3×107 MSun Peculiar environment: forming stars at extremely low rate (10 times lower than expected) Nevertheless ➜ Mini starburst
The Central Molecular Zone in X-rays Exposure > 1.5 Ms (central 15’) More than 100 EPIC observations > 200 ks in the plane X-ray binaries No powerful starburst! Ponti+15 Sgr A* ➜ Very faint! What is the present activity of Sgr A*? Can Sgr A* influence our CGM? 140 pc 1 deg ESA News/XMM-Newton/G. Ponti+15
The Central Molecular Zone in X-rays Exposure > 1.5 Ms (central 15’) More than 100 EPIC observations > 200 ks in the plane Ponti+15 X-ray binaries Sgr A* ➜ Very faint! 140 pc 1 deg ESA News/XMM-Newton/G. Ponti+15
The Central Molecular Zone in X-rays Exposure > 1.5 Ms (central 15’) More than 100 EPIC observations > 200 ks in the plane Ponti+15 X-ray binaries Sgr A* ➜ Very faint! Sgr A’s bipolar lobes Gillessen +09; +12 140 pc 1 deg ESA News/XMM-Newton/G. Ponti+15 Ponti +15
Sgr A*’s quiescent emission X-ray (Chandra) Wang+13 0.08 pc NIR (VLT-NACO) 2 arcsec 1.1 pc LSgr A* ~ 10-9 LEdd 0.5 arcmin Optically thin synchrotron Best target to study low luminosity accretion r ~ 10 RS Linearly polarised Marrone +06 Yuan +03; Ponti +17b Thermal e- (ɣe~10) ne ~ 106 cm-3 Loeb +07; Genzel +10 B ~ 20-50 G Soon ➜ Event horizon telescope! RIAF radial dependence Radio flattening matter > 90 % outflow! Likely from a compact jet Falcke +98; Moscibrodzska +10 ADAF/RIAF Quiescent Sgr A*’s activity ➜ No influence on CGM Wang+13 Wang +13 Bremsstrahlung r ~ 105 RS extended (~1”) accretion from stars wind Falcke +98; Markoff +01; Yuan +03; Zhao +03; +04; Baganoff +03; kTe ~ 7×107 K Melia +92; Quataert Herrnstein +04; An +05; Xu +06; Marrone +06; +07; Schoedel +07; 02; Baganoff +03; +11; Dodds-Eden +09; Trap +11; Wang +13; Bower +15; +18; +19; ne ~ 100 cm-3 Cuadra +05; Xu +06; Brinkerink +15; Liu +16; Stone +16; Witzel +18; Lu +18; von Wang +13 Fellenberg 18; Fazio +18; Iwata +20 ; Gravity Coll. +20
X-ray flares of Sgr A* Ponti +15b Chandra (1999-2006) Sgr A*’s flare distribution Neilsen+13 ~ 1.9±0.3 Flaring rate ~ 1 day-1 Flares L>1035 erg s-1 ~ 0.1 day-1 Baganoff+01; Goldwurm+03; Porquet+03;+08; Belanger+05; Nowak+12; Neilsen+13;+15; Degenaar+13; Barriere+14; Ponti+15; Mossoux+16; Yuan+16; Zhang+17; Capellupo+17; Yuan+18; Leibowitz+18;+20; Fazio+18; Okuda+19; Boyce+19; Haggard+19; Bouffard+19; Gutierrez+20; Ball+20; Subroweit+20; Ripperda+20; Gravity Coll+20
Sgr A*’s emission during X-ray flares? Best target to study low luminosity accretion During flares ➜ IR ~ 1.6 IR polarised ➜ Synchrotron ɣe>106 ∆ =0.5 ADAF ɣe~102 ∆ =whatever Yuan +03 Ponti +17b For 15 years we wondered… Genzel +10 What is the radiative process in X-ray?
First NIR and X-ray spectrum of a flare Second brightest flare ever detected by XMM XMM NuSTAR Sinfoni Ponti +17b
First NIR and X-ray spectrum of a flare Ponti +17b IR = 1.7±0.1; X = 2.27±0.12 ➜ ∆ = 0.57±0.09 ➜ B = 9±3 G XMM+NuSTAR Synchrotron with cooling break! ɣe>106 Is this flare peculiar? We want spectroscopy of more flares
Sgr A*’s present activity Was Sgr A* brighter in the past? Ponti +13; +14; +15b; +17b Current activity ➜ No influence on CGM
Clouds: mirrors of past activity Sunyaev +93 ➜ Tool to study Sgr A*’s past activity Molinari +11 ➜ Tomography Central of cloud distribution Molecular Zone Herschel column density map Sgr A* L d A, nH 140 pc 1 deg nH × A× I FeK LSgrA* ∝ Molinari +11 d2
Clouds as X-ray mirrors GRANAT: Hard X-ray/MC ASCA: Fe K from some MC Sunyaev +93 Koyama +96
Are clouds reflecting Sgr A* radiation? Puzzling result: constant FeK emission Cosmic ray electrons Is theFeK ; Contours: 850μm; X-ray emission 20cm Revnivtsev +04 induced by cosmic rays? Yusef-Zadeh +02+07 Cosmic ray protons HESS TeV on FeK map Aharonian +06
Super-luminal echo ➜ clouds as mirrors XMM: Fe K emission Ponti +10 Significant variation of the Fe K emission Super-luminal Fe K LSgr A* ~ 2×1039 erg s-1 (106 times brighter) propagation Implies: ~102 years ago ➜ Rule out cosmic rays ➜ Clouds are mirrors of past activity Corroborated by several other super-luminal echoes Clavel +13; Terrier +18 e.g. Ponti +10;+13
Some recent major results Mori +15; Zhang +15 NuSTAR: 10-20 keV Emission in hard X-rays ➜ Reflection Clavel +13 Chandra light curves Clavel +13 2 years event 10 years event Multiple outbursts?
Some recent major results Terrier+18 Fe K⍺ emission All Fe K⍺ bright regions are variable See also Ponti+10;+13;+14; Clavel+13;+14; Yusef-Zadeh+13a,b;+19; Marin+14; Koyama+14;+18; Zhang+15; Mori+15; Nobukawa+15; +16; Walls+16; Krivonos+14;+17; Churazov+17a,b,c; Chuard+18; Chernyshov+18; Kuznetsova+19; Di Gesu+20; Khabibullin+20a,b
Future prospects: X-ray polarisation! Reflection Degree Compton of scattered polarisation Fe K⍺ emission Cloud distribution in central molecular zone Kruijssen +15 Churazov+17b ➜ polarised Angle and degree of polarisation Achievable with IXPE (2021) EXTP (2027) Churazov+02+17b; Di Gesu+20; Khabibullin+20b Churazov+17b See also Churazov+02; Di Gesu +20; Khabibullin+20b ➜ Derive Sgr A*’s light curve Churazov+17b ➜ Reconstruct 3-d distribution of clouds See also Ponti+10;+13;+14; Clavel+13;+14; Yusef-Zadeh+13a,b;+19; Marin+14; Koyama+14;+18; Zhang+15; Mori+15; Nobukawa+15; +16; Walls+16; Krivonos+14;+17; Churazov+17a,b,c; Chuard+18; Chernyshov+18; Kuznetsova+19; Di Gesu+20; Khabibullin+20a,b
Sgr A*’s present and past activity LSgr A* ~ 2×1039 erg s-1 ~102 years ago Can we go further back in time? Ponti +13; +14; +15b; +17b Although 106 times brighter ➜ No influence on CGM
Distribution of remnants and outflows Ponti +15 Si xiii, S xv, Ar xvii 140 pc 1 deg Possible Atlas of all (~15) influence SNR in the region on CGM? ➜ Powering outflows to 3.5×10-4 yr-1 < SN rate < 15×10-4 yr-1 Galactic center lobe? Law +11; Crocker +11; 12; Massive kinetic energy input > 1.1×1040 erg s-1 Yoast-Hull +14; Jouvin +15
Discovery of high latitude hot plasma What is this? Ponti +15 AFGL 5376 Intensity of 1 keV Sgr A* thermal plasma
Galactic center radio lobe Radio emission Galactic Center Radio Lobe Law +08
What is the origin of this hot plasma? Hot atmosphere of the Galactic center? Base of Galactic wind? Crocker +12 Past Sgr A*’s AGN-like activity? Bland-Hawthorn & Cohen 03 Extensive X-ray scan Ponti +15 AFGL 5376 Intensity of 1 keV Sgr A* thermal plasma
Suspense….
ESA News/XMM-Newton/G. Ponti 2019, Nature 1.5-2.6 keV 2.35-2.56 S xv 2.7-3.0 keV Hot outflow Flow molecular matter
The Galactic ESA News/XMM-Newton/G. Ponti 2019, Nature 1.5-2.6 keV 2.35-2.56 S xv 2.7-3.0 keV center 1 Chimneys Ponti +2019, Nature Counts s-1 (keV-1 cm-2 arcmin-2) Ne ix Mg xi Si xiii S xv Ar xvii Ca xix Fe K Galactic latitude b = 0º b = -1.5º 10-5 -1 10-6 -1 1 2 5 Energy (keV) ➜ Measure kT, n, p, abundances of hot plasma -2 1 0 359 Galactic longitude
ESA News/XMM-Newton/G. Ponti 2019, Nature Hot plasma properties Surface brightness 10-3 Conical outflow Sgr A’s 1 bipolar lobes 10-4 5 Galactic latitude Chimneys ➜ impact on CGM Density (cm-3) 1 0.5 0.1 -1 Pressure (keV cm-3) 1 Hot plasma 0.1 flow -2 1 0 359 10 100 Galactic longitude Latitudinal distance in pc from Sgr A*
The radio view of the Chimneys ESA News/XMM-Newton/G. Ponti 2019, Nature Radio traces edges of Chimneys MeerKAT 1 Galactic latitude -1 Heywood +19, Nature Hot plasma flow -2 1 0 Galactic longitude 359 Outflow has radio counterpart
Multi-phase multi-epoch Galactic outflow Ponti+20 Hot plasma (X-rays) Coherent features warm dust (mid-IR) ➜ on > 102 pc scales SNR shocks (radio) SNR ➜ Deeply interconnected and linked to the Galactic outflow ➜ Strong shocks at the chimney-ISM interface (radio + shorter-lived dust emission) ➜ AFGL 5376 > 0.1 kpc molecular shock Uchida+94 Foreground Foreground SNR SNR X-rays: 1.5-2.6 keV Mid-IR: 22.2/12.08 μm Radio: 1.284 GHz
Large scale cold Galactic outflow Ponti+20 Base Fermi bubbles Base Fermi bubbles Di Teodoro+18 Di Teodoro+18 McClure-Griffith+13; Di Teodoro+18;+20; Lockman+20 AFGL 5376 similar to clouds at the base of the Fermi bubbles
Small scale molecular Galactic outflow Ponti+20 Molecular outflow (Polar Arc) Hsieh+16 X-ray only Ponti+15 Sgr A’s bipolar lobes Sgr A* . Molecular outflow (Hourglass feature) Hsieh+15;+16 Molecular outflow detected tens of parsec from Sgr A* 15 pc
Multi-phase multi-epoch Galactic outflow Ponti+20 Hot plasma (X-rays) Coherent features warm dust (mid-IR) ➜ on > 102 pc scales SNR shocks (radio) SNR ➜ Deeply interconnected and linked to the Galactic outflow ➜ Strong shocks at the chimney-ISM interface (radio + shorter-lived dust emission) H3+ survey ➜ outflow of warm diffuse gas Oka+20 ➜ AFGL 5376 > 0.1 kpc molecular shock Foreground ➜ Multi-phase (hot, molecular, warm-diffuse) Foreground SNR ➜ Multi-scale and multi-epoch outflow SNR X-rays: 1.5-2.6 keV Mid-IR: 22.2/12.08 μm Radio: 1.284 GHz
Multi-phase multi-epoch Galactic outflow Ponti+20 Hot plasma (X-rays) Coherent features warm dust (mid-IR) ➜ on > 102 pc scales SNR shocks (radio) SNR ➜ Deeply interconnected and linked to the Galactic outflow n io s ➜ Strong shocks at the chimney-ISM ru ot Pr interface (radio + shorter-lived dust emission) ➜ AFGL 5376 > 0.1 kpc molecular shock Foreground ➜ Multi-phase (hot, molecular, warm-diffuse) Foreground SNR ➜ Multi-scale and multi-epoch outflow ➜ Vertical (dominant? B~0.1-1 mG) magnetic SNR field diverging beyond |b|~0.5º ➜ Hot (X-ray) plasma cannot drive outflow Relic? Dark? outflow What we do not understand: Radio: 1.284 GHz Origin of protrusion? X-rays: 1.5-2.6 keV Why not perfectly symmetric? Mid-IR: 22.2/12.08 μm Relic outflow? Dark outflow? Radio: 1.284 GHz AGN driven? Starburst?
5 kpc Fermi RGB image Selig +15
The channel feeding the Fermi bubbles Does have an effect on CGM! ESA News/XMM-Newton/G. Ponti et al. 2019, Nature
Summary X-ray polarisation ➜ Derive Sgr A*’s light curve ➜ 3-d distribution of clouds Normal galaxies hold outflows to CGM Or longer-lived Starbursts? How is the disc-CGM exchange? Synchrotron with cooling break! ➜ Discovered the channel connecting the activity at the Milky Way center with the Fermi bubbles ➜ Outflow multi-phase, multi-epoch and multi-scale Ponti +13; +14; +15b; +17b
eROSITA (Spektr-RG)’s launch Baikonur, July 13th, 2019 Source: Roscosmos Merloni, Munich JAC, 30/4/2020 43
Map the flows of hot Galactic Baryons Global outflow? Inner outflow outer inflow? ? ? ? Milky Way center ? Fountains? Chaotic flow?
Conclusions X-ray polarisation ➜ Derive Sgr A*’s light curve ➜ 3-d distribution of clouds ➜ Discovered the channel connecting the activity at the Milky Way center with the Fermi bubbles ➜ Outflow multi-phase, multi-epoch and multi-scale Starbursts? eROSITA ➜ flows of hot Baryons between the Galactic disc and halo Synchrotron with cooling break! Ponti +13; +14; +15b; +17b
How can a super-luminal echo happen? Projector Wall Velocity observed on the screen 1m/1s To change slide 1 s Wall distant 1 m e.g. Ponti +10;+13
How can a super-luminal echo happen? Wall Projector Velocity observed on the screen 3c!!! To change slide 1 s Wall distant ~900000 km The physical variations happens in the projector! e.g. Ponti +10;+13
Conclusions X-ray polarisation ➜ Derive Sgr A*’s light curve ➜ 3-d distribution of clouds Starburst? ➜ Discovered the channel connecting the Synchrotron with activity at the Milky Way center with the cooling break! Fermi bubbles ➜ Outflow multi-phase, multi-epoch and multi-scale Ponti +13; +14; +15b; +17b
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