Strong Limits on Accreting IMBHs in Globular Clusters Laura Chomiuk - - PowerPoint PPT Presentation

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strong limits on accreting imbhs in globular clusters
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Strong Limits on Accreting IMBHs in Globular Clusters Laura Chomiuk - - PowerPoint PPT Presentation

Dec 13, 2023 284 likes •487 views

Strong Limits on Accreting IMBHs in Globular Clusters Laura Chomiuk (Michigan State) with Jay Strader (MSU) Laura Shishkovsky (MSU) Evangelia Tremou (MSU) Tom Maccarone (Texas Tech) James Miller-Jones (Curtin) Anil Seth (Utah) Craig

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SLIDE 1

Strong Limits on Accreting IMBHs in Globular Clusters

Laura Chomiuk (Michigan State) with

Jay Strader (MSU) Laura Shishkovsky (MSU) Evangelia Tremou (MSU) Tom Maccarone (Texas Tech) James Miller-Jones (Curtin) Anil Seth (Utah) Craig Heinke (Alberta) Greg Sivakoff (Alberta) Eva Noyola (UNAM)

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SLIDE 2

Expanding the sample of GCs with deep radio observations

M15 M22 Terzan 5 M10 M55 M4 M19 M62 47 Tuc M28 M5 NGC 6712 NGC 6352 NGC 3201

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SLIDE 3

Selecting clusters for likelihood of detecting IMBHs and stellar-mass BHs:

Massive & Nearby *or* Really massive

To be observed Yes, BH candidates No BH candidates

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SLIDE 4

Expansion Approved!

280 Hours on Jansky VLA: 28 GCs (Dec > -35 deg), each reaching sensitivity 1σ = 1.5 μJy 560 Hours on ATCA: 26 Southern GCs, each reaching sensitivity 1σ = 3.5 μJy

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SLIDE 5

Spanning a range of cluster properties

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SLIDE 6

Searching for IMBHs with the “Fundamental Plane” of BH activity


valid in low/hard state

Lr ~ Lx0.6

Merloni et al. 2003

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SLIDE 7

Predicting radio emission from IMBHs

  • 1. Globular clusters have gas

from giants

  • 2. Some gas will accrete onto

IMBH

  • 3. Accretion will produce X-ray

and radio emission with some efficiency

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SLIDE 8

formalism: Maccarone (2004), Maccarone & Servillat (2008), Strader et al (2012)

(i) ICM density: 0.2 cm-3 (ii) Accretion rate: 3% of Bondi (iii) efficiency: (not 0.1) (iv) (v) IMBH is on fundamental plane

Predicting radio emission from IMBHs

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SLIDE 9

Predicting radio emission from IMBHs: Typical Numbers

Accretion rate is 0.1%

  • f wind from a single

red giant.

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SLIDE 10

Predicting radio emission from IMBHs: Typical Numbers

Accretion rate is 0.1%

  • f wind from a single

red giant. Radiative efficiency comparable to Sgr A*.

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SLIDE 11

IMBH Non-detections in all GCs

(16, to date)

MBH <~ 980 M! MBH <~ 730 M! MBH <~ 360 M!

Strader et al (2012)

Ter 5 M62

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SLIDE 12

X-ray observations place similar limits.

ω Cen

(Haggard et al. 2013)

291 ks of Chandra time At center: < 1.6x1030 erg/s MBH < 4x103 M☉

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SLIDE 13

But radio observations are more efficient.

7 μJy radio (8 ks on VLA)

  • r

(36 ks on ATCA) *equivalent to* 1.6x1030 erg/s X-ray (291 ks on Chandra)

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SLIDE 14

Strong Limits on IMBHs in GCs

(16, to date) (Distance matters)

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SLIDE 15

IMBHs aren’t so massive. *or* Accretion is very inefficient .

1) ICM density 2) Fraction of Bondi 3) Radiative efficiency:

(Maccarone 2003). Requiring continuity es ϵ = 0.1 (( ˙ M/ ˙ Medd)/0.02) assume that ˙ is given by 3%

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SLIDE 16

Strong Limits on IMBHs in GCs

(16, to date)

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SLIDE 17

A clever strategy for expanding IMBH searches

Wrobel, Miller-Jones & Nyland in prep

Stack of 245 GCs in NGC 1023 (11 Mpc)

rms ~ 1.2 μJy/beam in just 5 minutes on source!

5 minute stack 10 hour single

M22 NGC 1023

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SLIDE 18

A clever strategy for expanding IMBH searches

Wrobel, Miller-Jones & Nyland in prep

Stack of 245 GCs in NGC 1023 (11 Mpc)

rms ~ 1.2 μJy/beam in just 5 minutes on source!

5 minute stack 10 hour stack 10 hour single

M22 NGC 1023

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SLIDE 19

Future stacks of MW GCs will give deepest limits.

Survey Stack

‹❯ ≲300 M☉ ›❰ at ‹❯ 7 kpc ›❰

Stay Tuned!