ultraluminous x-ray sources with nustar & friends

M A T T E O B A C H E T T I T H E N U S TA R U L X P R O G R A M

M A T T E O B A C H E T T I W I T H D . B A R R E T, F. H A R R I S O N , J . M . M I L L E R , V. R A N A , D . W A LT O N , T H E N U S TA R U L X W G , A N D T H E N U S TA R T E A M D U B L I N , J U N E 1 9 T H, 2 0 1 4

U LT R A L U M I N O U S X - R AY S O U R C E S W I T H N U S TA R & F R I E N D S


W H Y “ U LT R A L U M I N O U S ” ?

LULX > 1039erg/s

Standard accretion limit on stellar-mass BHs

High BH mass?Super-Eddington accretion?

LEdd ⇡ 1.38 · 1038 M

M�erg/s

⇡ 1.38 · 1039 M

10M�erg/s


U L X S P E C T R A I N T H E X M M E R A

• Three main spectral shapes

• The same source can show one or more of these spectral states

• Broadened disk usually in low-luminosity sources

Sutton+13





Sutton+13



• Mostly Persistent!

• A soft excess(?)

• A hard turnover(?)



S P E C T R A L P R O P E R T I E S O F U L X S ( < 1 0 K E V )






• Standard disk cut at the ISCO? (IMBH! e.g. Miller+04)

• Blurred emission lines? (e.g. Caballero-Garcia+10)

• A partially covered disk? (e.g. Gladstone+09)

• A soft deficit? (e.g. Gonçalves+06)• Mostly Persistent!





• Standard disk cut at the ISCO? (IMBH! e.g. Miller+04)

• Blurred emission lines? (e.g. Caballero-Garcia+10)

• A partially covered disk? (e.g. Gladstone+09)

• A soft deficit? (e.g. Gonçalves+06)

• A cutoff? (e.g. Stobbart+06)

• A turnover due to a broadened iron complex? (e.g. Caballero-Garcia+10)

• A second disk component? (e.g. Miller+13)

• A conspiracy? An illusion?





P O S S I B L E M O D E L S B E F O R E N U S TA R


P O S S I B L E M O D E L S B E F O R E N U S TA R

• Standard low/hard state: low T, powerlaw. Below Eddington (-> implies IMBH)

• Reflection-dominated (Caballero-García & Fabian ’10)

• “Ultraluminous state” (Gladstone et al. 09)? Large “cold” corona, disk hidden -> favors stellar mass

• slim, or p-free, disk (Ebisawa et al, Kawaguchi et al.): deviation from SS73’s temperature-radius relation. Super-Edd accretion possible.

• beaming and outflows: large apparent luminosity due to beaming.

• “Patchy disks”


T H E N U S TA R U L X P R O G R A M

• ~10 ULXs to study (6 this year)

• For 2012-2013, a Large Program XMM+NuSTAR (~400ks), + Suzaku, Chandra



• ~10 ULXs to study (6 this year)

• For 2012-2013, a Large Program XMM+NuSTAR (~400ks), + Suzaku, Chandra

Harrison et al. 2013


• Sources were selected for flux and hardness in the XMM band

• Most sources of the sample historically in the hard and soft ultraluminous states



N G C 1 3 1 3 X - 1


N G C 1 3 1 3 X - 1

Bachetti+13, ApJ


C U T O F F S , C U T O F F S E V E R Y W H E R E

ALL sources in our sample show a cutoff above 10 keV


C U T O F F S , C U T O F F S E V E R Y W H E R E

ALL sources in our sample show a cutoff above 10 keV

Ho IX X-1

N1313 X-1

Cir ULX5IC 342 X-1

IC 342 X-2

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Ho II X-1

Bachetti+13, Walton+13, Walton+14, Rana+14

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E X C E S S E S , E X C E S S E S E V E R Y W H E R E ( ? )

Low energy: a disk-like component is detected in most sources below 1 keV.

High energy: In most cases the cutoff is not correctly described by single-kT Comptonization


E X C E S S E S , E X C E S S E S E V E R Y W H E R E ( ? )

Low energy: a disk-like component is detected in most sources below 1 keV.

High energy: In most cases the cutoff is not correctly described by single-kT Comptonization

IC 342 X-1

N1313 X-1

N1313 X-1

Bachetti+13, Rana+14


• Several sources showed a fast (~weeks) evolution of spectral shapes.

• Short-term variability appears mostly in the soft intermediate and broad disk states (as previously known).

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Ho IX X-1

N1313 X-2

Cir ULX5

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Cir ULX5

N1313 X-2






N5907 X-1

Walton+ in prep.


VA R I A B I L I T Y- W H AT W E H AV E L E A R N E D F R O M I T

• Temperature-luminosity relation deviates from SS disk in Cir ULX-5:

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• Spectral evolution highly non-standard

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VA R I A B I L I T Y- W H AT W E H AV E L E A R N E D F R O M I T

• Temperature-luminosity relation deviates from SS disk in Cir ULX-5:

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• Spectral evolution highly non-standard

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Walton+13, Walton+14

Ho IX X-1

Cir ULX5

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S U M M A R Y O F T H E P R O G R A M



• Sample of ULXs observed:

• NGC 1313 X-1, X-2 (XMM, NuSTAR, Chandra) -> Bachetti+13 ApJ, Miller+14 ApJL

• Cir ULX-5 (XMM, NuSTAR) -> serendipitous, Walton+13, ApJ

• IC 342 X-1, X-2 (XMM, NuSTAR) -> Rana+14, sub.

• Holmberg IX X-1 (or M81 X-9) (XMM, NuSTAR, Suzaku) -> Walton+14, acc.

• NGC 5204 X-1 (XMM, NuSTAR, Chandra) -> Mukherjee+ in prep.

• NGC 5907 X-1 (XMM, NuSTAR, Suzaku) -> Walton+ in prep.

• Holmberg II X-1










• Holmberg II X-1

• (+ HLX-1, M82 X-1, M51, ...)










• Holmberg II X-1

• (+ HLX-1, M82 X-1, M51, ...)

• Data analysis ongoing


C O N C L U S I O N S



• Thanks to NuSTAR, degeneracy of spectral models reduced drastically.




• Observed ULXs show common features (low-T cutoff, low-T disk or p disk-like spectra)





• No clear emission lines






• The hard state-like model is ruled out in all of them, as is the reflection-dominated regime in its simplest form. Spectrum more similar to “non-standard” very luminous BHs.







• An excess from single-component Comptonization?







• An excess from single-component Comptonization?

• -> No standard BH state. Favored interpretation quasi- or super-Eddington accretion in massive StMBHs


F U T U R E P L A N S



• Accepted (Swift+)XMM+NuSTAR program to sample more spectral states in NGC 1313 X-[12]



• Accepted (Swift+)XMM+NuSTAR program to sample more spectral states in NGC 1313 X-[12]

• New observations of NGC 5907 X-1 and other sources already planned

ultraluminous x-ray sources with nustar & friends

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