reconstructing the past activity of the supermassive black hole at the galactic centre r. terrier,...

Reconstructing the past activity of the supermassive black hole

at the Galactic Centre

R. Terrier, APC Paris M. Clavel, A. Goldwurm, M. Morris, G. Ponti, S. Soldi

COSPAR, Aug. 2014, Moscow

Active and inactive SMBH in the Universe

IC 2497: an extinct quasar?

109 Mo SMBH

Light echo of past quasar emission emitted ~ 70 kyr ago

Current luminosity is up to 104 smaller

Timescale of ~ 10 kyr is consistent with state changes observed in Galactic XRB (~1h)

Schawinski et al. (2010)

Transition timescale for Sgr A*: 50 yrs

What timescales for state transition of SMBH?

Active and inactive SMBH in the Universe

GRB 110328a/Sw 1644+57: Stellar disruption by SMBH?

Burrows et al. (2011), Levan et al. (2011) etc

IGR J12480+0134: ~150 days transient

Peak luminosity at 1.5 1042 erg/s ~ 0.2 L

edd

Radiated energy ~ 1050 erg

a tidal capture of Jupiter-like object?Nikolajuk & Walter (2013)

Timescales and recurrence time of catastrophic events near

SMBH?

Diffuse non-thermal emission from the central 100 pc

100 pc

Hard X-ray continuum emission from the central 200pc detected by ART-P: reflection of X-ray source?

Sunyaev+93

Intense 6.4 keV FeK line emission resolved from GC clouds:Past Sgr A* flare (300 yrs ago)?

Koyama+96

ASCA 6.4 keV

100 pc XMM 6.4 keV

Diffuse non-thermal emission from the central 100 pc

Hard X-ray continuum emission from the central 200pc detected by ART-P: reflection of X-ray source?

Sunyaev+93

Intense 6.4 keV FeK line emission resolved from GC clouds:Past Sgr A* flare (300 yrs ago)?

Koyama+96

Hard X-rays from Sgr B2

100 pc

Integral discovered hard X-ray emission (up to >100 keV) from Sgr B2 and G0.11-0.11 clouds

Revnivtsev+04, Belanger+06

The 6.4 keV & hard X-ray continuum emission from Sgr B2 is consistent with an echo from some past Sgr A* intense activity 1039 erg/s ~ 300 yrs ago

Are there other possible explanations?

200 pc

Origin of the non thermal X-ray emission from GC clouds?

Cosmic-ray bombardement? Illumination by past bright X-ray source?

1 keV 10 keV 1 keV 10 keV

Key observable is time variability!

SF2A 2004

Hard X-ray echo of past activity

LineContinuum

Clavel 14

Early evidences for variations of the emission

PRELIMINARYSgr B2 (20-60 keV)

6.4 keV flux variations in Sgr B2 region Inui+09

Sgr B2 (20-60 keV)

100 pcXMM 6.4 keV

Moving continuum diffuse clumps seen by Chandra in Sgr A region

Muno+07

Hard X-ray emission from Sgr B2 is fading!

Analysis of 20 Ms of Integral data from 2003 to 2009

PRELIMINARYSgr B2 (20-60 keV) 2009

2005

2003

Sgr B2

Integral IBIS/Isgri : 20-60 keV

2007

Illumination !

Terrier+10

Sgr B2 (20-60 keV)

Oph cluster

= 8.2 ± 1.7 yr

Hard X-ray emission from Sgr B2 is fading!

Suzaku observes similar decay in 2009 at 6.4 keV and in hard continuum band

PRELIMINARY 2009

2005

2003

Sgr B2

Integral IBIS/Isgri : 20-60 keV

2007

Nobukawa+11

Sgr B2 (20-60 keV)

A past flare of the SMBH is illuminating Sgr B2!

Distance implies

•Sgr A* is the most likely candidate•

to Earth

L X ∝10 39erg.s−1 d100pc

2

Photons scattered by Sgr B2 were emitted ~ 100 yrs

•Parallax measurement: Sgr B2 is 130 ± 60 pc in front of Sgr A*•

direct pathscattered path

Delay 100 yrs (70-150)

•(H2O maser, VLBI, Reid et al, 2009)

Time variability in the Sgr A complex?

100 pc

Sgr A

PRELIMINARY

the central 30 pc observed for 8 years

XMM-NewtonFe K 6.4 keV: 2000-2004

30 pc

PRELIMINARY

Flux variations in the central 30 pc

Fe K 6.4 keV: 2000-2004

30 pc

Fe K flux

Fe K flux

PRELIMINARY

Some propagation effects?

Fe K 6.4 keV: 2000-2004

30 pc

PRELIMINARY

Apparent superluminal motion!

Most solid proof that Fe K emission is caused by illumination

Sgr A* is illuminating most of the clouds in the GCPonti+10

To the GC

Apparent superluminal motion? Effect discussed by Sunyaev & Churazov (1998)

Curves of constant delay (isochrons) : parabola

Apparent light crossing times:

120 yrs70 yrs45 yrs

•If the « bridge » and Sgr B2 are illuminated by the same flare (1039 erg/s): Bridge located 60 pc behing Sgr A* & flare began 400 years ago?

A possible lightcurve of Sgr A* over past centuries?

Ponti+10

SF2A 2004

Sgr A* is fed by winds of surrounding massive stars:•Intrinsic accretion rate variability likely to weak•Stochastic infall of clumps from nearby massive stellar winds?

Cuadra et al. (2008)

Origin of the high Sgr A* state?

SF2A 2004

Deceleration of jet produced by stellar tidal disruption event?Yu et al (2011)

Asteroids and planet disruption?Zubovas et al (2012)

Accretion of debris produced by stellar collisions? Sazonov et al. (2012)

Multiple cloud accretion events?•Czerny et al. (2013)


SF2A 2004

Intrinsic accretion rate variability due to stochastic infall of clumps from nearby massive stellar winds?

Cuadra et al. (2008)

Deceleration of jet produced by stellar tidal disruption event?Yu et al (2011)

Asteroids and planet disruption?Zubovas et al (2012)

Accretion of debris produced by stellar collisions? Sazonov et al. (2012)

Multiple cloud accretion events?•Czerny et al. (2013)


Can we determine the light curve of Sgr A* over the last centuries?

PRELIMINARY

Constraining Sgr A* light curve over the past centuries

To reconstruct Sgr A* past activity:L

Sgr A* is a function of cloud N

H and radius

Time delay given by cloud position along LoS

3D distribution of GC molecular clouds is critical!

or or ?

Sofue95 Molinari+11

Existing 3D models from radio measurements are very uncertain

PRELIMINARY

Constraining Sgr A* light curve over the past centuries

Solution:

Use X-rays to constrain the GC clouds Line of Sight (LoS) position

Different approaches:

•Use angular dependency of 6.4 keV Equiv. Width Capelli+12

•Use X-ray intrinsic NH and measure partial absorption of GC thermal

plasmas to locate cloud along LoSRyu+09, Ryu+13

•Use lightcurve of echoes to associate clouds with similar delays:•X-ray tomography of GC ISM

Clavel+13

SF2A 2004

•Constrain cloud position along the line of sight using EW of Fe K line, and deduce Sgr A* luminosity from N

H deduced from X-ray spectrum

Towards a Sgr A* lightcurve

Capelli+12

SF2A 2004

Towards a Sgr A* lightcurve

Ryu+13

Clavel+13

Detailed timing of the echoes with Chandra

Chandra Fe Kα line flux: 1999-2011

Variations & propagation in all Sgr A complex clouds

More complex pattern than previous studies suggest

30pc

Clavel+13

Propagation follow-up in 2011

Chandra Fe Kα line flux: 1999-2011

A new thin (0.2 pc!) filament : Flux increases by a factor greater than 10

Filament illuminated by LX>1039 erg/s

30pc

Size: 0.2 x 1.0 pc2

dSgrA*

≥ 23 pcN

H ≤ 1023 cm-2

2011

1999-2010

Clavel+13

Distinct timing behaviours in the Sgr A complex echoes

2 distinct time behaviours: 10 yr linear increase or decrease2 yr peaked variation

Systematic lightcurve extraction in 15'' boxes (4-8 keV)

Clavel+13

Two distinct events reflected in Sgr A complex!

2 distinct events are required (<2 yrs and ~10 yrs timescale) with LX>1039 erg/s

Absolute timing still unkown

short var.long var.

SF2A 2004

Intense hard non-thermal X-ray emission (~1.6 up to 30 keV) around the Arches cluster

Capelli+10, Tatischeff+12, Krivonos+13

Inverse bremstrahlung emission of subrelativistic ions? Required power in CR ions:

PCR

= (0.5 – 1.8)×1039 erg s-1

Powered by collision between the Arches cluster and ambient cloud?

The Arches cluster: an accelerator of CR ions?

Archescluster

• CR energy density: ~ 1000 eV cm-3 The Arches cluster: an extreme CR dominated

region?Tatischeff+12

SF2A 2004

The Arches cluster: an accelerator of CR ions?

Look for time variability of 6.4 keV and continuum emission over 13 yrs

A 30% flux variation observed in 2011-2013

Most of the non-thermal X-ray flux from Arches cluster surroundings is due to reflection of Sgr A* past flare

Clavel+14, see poster STW-S-132, presentation by R. Krivonos

continuum

Fe K

The Fe K emission of the CMZ 10 years apart

2000

2012

Comparison of XMM surveys reveals variations over the whole CMZ:•Overall decrease•Strong variations in Sgr C complex

See S. Soldi presentation

100 pc XMM, 6.4 keV FeK line

2012

Solid proof that Sgr A* activity has changed in recent past Hard X-ray and Fe K emission is highly variable in the central 200pc

Reflection of hard & energetic events from Sgr A* Arches emission is dominated by reflection

Towards a lightcurve of Sgr A* over the last millenium? Strong uncertainties in the LoS distribution of clouds

X-rays can be used to constrain it

Use X-ray echoes timing (tomography) and large scale surveys to improve knowledge on cloud position

Detailed Chandra monitoring reveal at least 2 distinct events High luminosities >1039 erg/s Durations: <2 yrs, ~10 yrs respectively

Disruption events? Strong fluctuations in accretion rate? Further constraints from XMM (Soldi's talk), Suzaku (Nobukawa's talk)

Conclusions

Sgr A* : the dormant SMBH of the Milky Way

0.3 pc

Faint Galactic Centre source Sgr A* powered by a 4 106 Mo SMBH

(Ghez et al., 2008, Gillessen et al, 2009)

Sgr A*: a laboratory to study dormant SMBH and their possible state transitions

Sgr A*: quiescent emission

Quiescent emission luminosity ~ 1036 erg/s i.e. a few 10-8 Ledd

Resolved by Chandra (r~1.4'' ~ Rbondi

), aligned with massive star disk

LX ~ 2 1033 erg/s Baganoff et al. (2003) , Wang et al. (2013)

Massive stars wind accretion rate at Bondi radius 10-5 Mo/yr

Accretion rate at the SMBH < 10-7 Mo/yr!

Sgr A*

Chandra

Genzel et al (2010)

Wang et al. (2013)

Looking for Sgr A* flares in hard X-rays

• Sgr A* exhibits flaring activity in X-rays

• Flare frequency: 1.1± 0.2 day-1 Typical duration: ~ 1 ks• dN/dL L-1.9

• Neilsen et al. (2013)

• Most intense flare detected at LX ~ 5 1035 erg/s

• (e.g. Goldwurm et al. 2003, Porquet et al. , 2008, Nowak et al 2012)

XMM-NewtonApr. 2007

Trap et al. (2010)

X-ray spectrum w.r.t. to LoS position

Constrain geometry with the full spectrum X-ray – hard X-rayNuStar/Astro-H?

reconstructing the past activity of the supermassive black hole at the galactic centre r. terrier,...

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