A Possible New Test of the M BH - Relation at Globular Cluster Masses

A Possible New Test of the MA Possible New Test of the MBHBH - -

Relation at Globular Cluster MassesRelation at Globular Cluster Masses

Steve ZepfSteve Zepf

Michigan State UniversityMichigan State University

Collaborators Collaborators Arunav KunduArunav Kundu Tom Maccarone Tom Maccarone Katherine Rhode Gilles Bergond Katherine Rhode Gilles Bergond Stephen Shih Chris Waters Stephen Shih Chris Waters

MMBHBH - - is a key relation for galaxies. What happens at low masses corresponding to dwarfs and GCs?

What does comparison of What does comparison of MMBHBH - - at high and low masses say at high and low masses say

about relationship between BH growth and galaxy about relationship between BH growth and galaxy growth? Is the growth? Is the MMBHBH - - relation one of the ways dwarfs relation one of the ways dwarfs

and GCs differ? and GCs differ?

•• Dwarfs tend to have too few stars near center for dynamical Dwarfs tend to have too few stars near center for dynamical measurements (radio may be more promising).measurements (radio may be more promising).

•• GCs better, but still a problem. All Galactic GCs are GCs better, but still a problem. All Galactic GCs are consistent with consistent with MMBHBH = 0 (M15 = 1000 +/- 1000 Msun, = 0 (M15 = 1000 +/- 1000 Msun,

47 Tuc 700 +/- 700 Msun).47 Tuc 700 +/- 700 Msun).

•• Also, no black-hole X-ray binaries in globular clusters, even Also, no black-hole X-ray binaries in globular clusters, even though many neutron-star XRBs in GCs.though many neutron-star XRBs in GCs.

Black Holes and Globular ClustersBlack Holes and Globular Clusters

Are BHs absent in GCs (ejection?,IMF?) or are they Are BHs absent in GCs (ejection?,IMF?) or are they hiding? hiding?

•• Well-known handful of LMXBs in extragalactic GCs have Well-known handful of LMXBs in extragalactic GCs have LLXX well above L well above LEddEdd for a neutron star, based on for a neutron star, based on matching Chandra data for LMXBs with HST and matching Chandra data for LMXBs with HST and ground-based spectroscopy of GCs (Irwin; Fabbiano ground-based spectroscopy of GCs (Irwin; Fabbiano & Kim; Kundu, Maccarone, & Zepf). & Kim; Kundu, Maccarone, & Zepf).

•• But…extragalactic GCs are not spatially resolved in X-But…extragalactic GCs are not spatially resolved in X-ray data, thus multiple NS sources possible, even likely ray data, thus multiple NS sources possible, even likely (KMZ07). This has been known for a long time. So has (KMZ07). This has been known for a long time. So has a solution (e.g. Kalogera, King & Rasio 2004) – a solution (e.g. Kalogera, King & Rasio 2004) – Variability is an unambiguous indicator of a BH, since Variability is an unambiguous indicator of a BH, since multiple NSs can’t conspire to vary together. multiple NSs can’t conspire to vary together.

•• Nothing really seen in a AR Chandra study (Irwin 2006)Nothing really seen in a AR Chandra study (Irwin 2006)but… but…

A Black Hole in a Globular Cluster!A Black Hole in a Globular Cluster! Maccarone, Kundu, Zepf, & Rhode 2007 NatureMaccarone, Kundu, Zepf, & Rhode 2007 Nature

- L- LXX 4 x 10 4 x 103939 ergs/s LMXB in NGC 4472 ergs/s LMXB in NGC 4472

- In a spectroscopically confirmed globular cluster- In a spectroscopically confirmed globular cluster- Metal-poor GC, 6.6’ from center (about 4 Re)- Metal-poor GC, 6.6’ from center (about 4 Re)

Why Black Hole?Why Black Hole?

•• XMM observations show decrease in soft X-ray flux by a XMM observations show decrease in soft X-ray flux by a factor of 7 over 10,000s. Rules out multiple NSs! Presence factor of 7 over 10,000s. Rules out multiple NSs! Presence in GC, and thus requirement of LMXB rules out other in GC, and thus requirement of LMXB rules out other extant non-BH explanations. extant non-BH explanations.

•• Drop in LDrop in LXX almost all at low energies, suggests eclipsing almost all at low energies, suggests eclipsing blackbody emission from inner disk. Ingress time blackbody emission from inner disk. Ingress time indicates precessing warped outer disk (Shih, Maccarone, indicates precessing warped outer disk (Shih, Maccarone, Kundu, & Zepf 2007)Kundu, & Zepf 2007)

XMM time series of NGC 4472 GC BH source, MKZR07XMM time series of NGC 4472 GC BH source, MKZR07

Shih, Maccarone, Kundu, & Zepf 2007, MNRAS, submitted Shih, Maccarone, Kundu, & Zepf 2007, MNRAS, submitted

Chandra observation 3.5 years earlier at high luminosity level. Chandra observation 3.5 years earlier at high luminosity level.

• • Separate work of ours using VLT Separate work of ours using VLT FLAMES multifiber FLAMES multifiber spectroscopy to study spectroscopy to study kinematics of GC system of kinematics of GC system of NGC 4472.NGC 4472.

• • Two independent fiber spectra of Two independent fiber spectra of GC hosting the black hole. GC hosting the black hole. Spectral resolution R=6000, Spectral resolution R=6000, wavelength coverage 5000Å < wavelength coverage 5000Å < λλ < 5800Å.< 5800Å.

•• Observed 5031.2 +/-0.3 Å is Observed 5031.2 +/-0.3 Å is exactly the expected wavelength exactly the expected wavelength for [OIII] 5007 at the GC radial for [OIII] 5007 at the GC radial velocity of 1475 km/s. velocity of 1475 km/s.

•• Line has a FWHM of 4-6 Å, Line has a FWHM of 4-6 Å, instrumental resolution 0.9Å instrumental resolution 0.9Å Velocity width of 200-350 km/s.Velocity width of 200-350 km/s.

•• Rules out PNe and implicates BH Rules out PNe and implicates BH XRB as the source of the power XRB as the source of the power driving the [OIII] emission.driving the [OIII] emission.

[OIII] 5007 at refdshift of GC![OIII] 5007 at refdshift of GC!

Zepf, Maccarone, Bergond, Kundu, Rhode, & Salzer Zepf, Maccarone, Bergond, Kundu, Rhode, & Salzer 2007, APJL, submitted2007, APJL, submitted

Where does the line come from and what Where does the line come from and what does it ultimately say about Mdoes it ultimately say about MBHBH ? ?

[OIII] can either be collisionally or photoionized[OIII] can either be collisionally or photoionized

Possibility #1Possibility #1 – stellar mass black holes with mildly super- – stellar mass black holes with mildly super-Eddington LEddington LXX drive strong winds (e.g. Begelman, King, & drive strong winds (e.g. Begelman, King, & Pringle 2006). This wind will shock into ISM of GC, classic Pringle 2006). This wind will shock into ISM of GC, classic shock solutions work with GC sizes of ~10pc and observed shock solutions work with GC sizes of ~10pc and observed velocity width. Note sub-Eddington IMBHs will not drive velocity width. Note sub-Eddington IMBHs will not drive such winds (Proga 2007).such winds (Proga 2007).

Possibility #2 Possibility #2 – line is photoionized. Velocity width much greater – line is photoionized. Velocity width much greater than GC dispersion requires that this happen in accretion than GC dispersion requires that this happen in accretion disk around BH. May work for IMBHs, although tricky to get disk around BH. May work for IMBHs, although tricky to get enough mass at the right radius to make observed L[OIII] at enough mass at the right radius to make observed L[OIII] at right velocity. The broad lines seen in Galactic stellar mass right velocity. The broad lines seen in Galactic stellar mass BHs are higher ionization species, as expected from the small BHs are higher ionization species, as expected from the small distance from the BH required to get the observed velocity.distance from the BH required to get the observed velocity.

Collisional likely stellar mass BH, photoionized likely IMBHCollisional likely stellar mass BH, photoionized likely IMBH

MMBHBH - - Relation

•• If the XRB is a stellar mass BH, it is very unlikely an IMBH If the XRB is a stellar mass BH, it is very unlikely an IMBH is in the globular cluster. The BHs are the heaviest is in the globular cluster. The BHs are the heaviest objects in the cluster and quickly relax to the center. objects in the cluster and quickly relax to the center. There they either coalesce or are ejected. In a GC with There they either coalesce or are ejected. In a GC with an IMBH, any stellar mass BHs must spend most of their an IMBH, any stellar mass BHs must spend most of their time in the outer regions of the GC. However, this is time in the outer regions of the GC. However, this is exactly *not* where the stellar dynamical interactions exactly *not* where the stellar dynamical interactions that make close accreting binaries with BH primaries that make close accreting binaries with BH primaries occur. occur.

•• So how to tell if BH XRB is an IMBH or stellar mass BH:So how to tell if BH XRB is an IMBH or stellar mass BH:

1. 1. collisional vs. photoionizationcollisional vs. photoionization 2.2. Imaging size of emission line nebula (10 pc > 0.1”) Imaging size of emission line nebula (10 pc > 0.1”)2.5.2.5. Variability in emission line Variability in emission line

Conclusions

1. A black hole is confirmed in one globular cluster. 1. A black hole is confirmed in one globular cluster. (Maccarone, Kundu, Zepf, & Rhode 2007, Nature, 445, 183)(Maccarone, Kundu, Zepf, & Rhode 2007, Nature, 445, 183)

2. The variability that confirms the BH XRB in a globular cluster appears 2. The variability that confirms the BH XRB in a globular cluster appears to be due to a warped accretion disk precessing into the line of sight to be due to a warped accretion disk precessing into the line of sight (Shih, Maccarone, Kundu, & Zepf 2007, MNRAS, submitted)(Shih, Maccarone, Kundu, & Zepf 2007, MNRAS, submitted)

3. Optical spectroscopy reveals [OIII] 5007 emission from the BH XRB 3. Optical spectroscopy reveals [OIII] 5007 emission from the BH XRB system. May either be collisional or photoionization (Zepf et al. system. May either be collisional or photoionization (Zepf et al. 2007, ApJL, submitted). 2007, ApJL, submitted).

4. Collisional ionization would suggest a stellar mass BH, photoionization 4. Collisional ionization would suggest a stellar mass BH, photoionization an IMBH. an IMBH.

5. If it is a stellar mass BH, the GC is unlikely to host an IMBH and 5. If it is a stellar mass BH, the GC is unlikely to host an IMBH and would fall off of the extension of the would fall off of the extension of the MMBHBH - - relation. If it is an relation. If it is an IMBH, it is the second confirmed IMBH in a globular cluster (see IMBH, it is the second confirmed IMBH in a globular cluster (see Ulvestead, Greene, & Ho 2007, aUlvestead, Greene, & Ho 2007, arXiv:0704.1458 for G1)rXiv:0704.1458 for G1) .

A Possible New Test of the M BH - Relation at Globular Cluster Masses

Documents

Transcript of A Possible New Test of the M BH - Relation at Globular Cluster Masses