Simulating the mass assembly history of Nuclear Star Clusters

Transcription

1 Simulating the mass assembly history of Nuclear Star Clusters The imprints of cluster inspirals Alessandra Mastrobuono-Battisti Sassa Tsatsi Hagai Perets Nadine Neumayer Glenn vad de Ven Ryan Leyman David Merritt Roberto Capuzzo-Dolcetta Fabio Antonini Avi Loeb Stellar Aggregates, Bad Honnef,

2 Nuclear Star Clusters (NSCs) are observed at the center of most galaxies 10 = 87pc 1.2kpc x 1.2kpc Neumayer et al 2011, Carollo et al. 1998, Matthews et al. 1999, Böker et al. 2002, 2003, 2004, Böker 2010, Côte et al. 2006

3 Nuclear Star Clusters (NSCs) are observed at the center of most galaxies 10 = 87pc NSC 1.2kpc x 1.2kpc Neumayer et al 2011, Carollo et al. 1998, Matthews et al. 1999, Böker et al. 2002, 2003, 2004, Böker 2010, Côte et al. 2006

4 The Milky Way has a NSC hosting a central Massive Black Hole

5 NSCs form through cluster infall and/or insitu star formation The in-situ star formation or gas model (Loose et al. 1982, Schinnerer et al. 2008, Milosavljevic 2004, Pflamm-Altenburg, Jan & Kroupa 2009), possibly in a disk like configuration. The cluster merger scenario (Tremaine et al. 1975, Ostriker 1988, Antonini, Capuzzo Dolcetta, MB & Merritt 2012, Antonini 2013, Gnedin et al and references therein). Both processes can work in concert, and both could be important for the formation and evolution of NSCs.

6 We modelled NSC formation from cluster infalls using N-body simulations Initially: only the nuclear bulge of the galaxy; An MBH (4x10 6 M ) is at the center of the galaxy; The NSC is build up by consecutive infalls; Collisional evolution of the NSC. Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt, 2012 ApJ; Perets & Mastrobuono- Battisti,2014, ApJ; Mastrobuono-Battisti, Perets & Loeb, 2016, ApJ; Tsatsi, Mastrobuono-Battisti et al., 2016, MNRAS

7 We modelled NSC formation from cluster infalls using N-body simulations 10 8 M Nuclear bulge Massive Black Hole M (Milky Way-like) Initially: only the nuclear bulge of the galaxy; An MBH (4x10 6 M ) is at the center of the galaxy; The NSC is build up by consecutive infalls; Collisional evolution of the NSC. Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt, 2012 ApJ; Perets & Mastrobuono- Battisti,2014, ApJ; Mastrobuono-Battisti, Perets & Loeb, 2016, ApJ; Tsatsi, Mastrobuono-Battisti et al., 2016, MNRAS

8 We modelled NSC formation from cluster infalls using N-body simulations 10 8 M Nuclear bulge Massive Black Hole M (Milky Way-like) Initially: only the nuclear bulge of the galaxy; 12 GCs with random orientations An MBH (4x10 6 M ) is at the center of the galaxy; 1.1 The 10 6 MNSC is build up by consecutive infalls; Collisional evolution of the NSC. Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt, 2012 ApJ; Perets & Mastrobuono- Battisti,2014, ApJ; Mastrobuono-Battisti, Perets & Loeb, 2016, ApJ; Tsatsi, Mastrobuono-Battisti et al., 2016, MNRAS

9 We modelled NSC formation from cluster infalls using N-body simulations 10 8 M Nuclear bulge Initially: only the nuclear bulge of the galaxy; 12 GCs with random orientations An MBH (4x10 6 M ) is at the center of the galaxy; ~12 Gyr Nuclear Star Cluster Massive Black Hole M (Milky Way-like) 1.1 The 10 6 MNSC is build up by consecutive infalls; Collisional evolution of the NSC M Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt, 2012 ApJ; Perets & Mastrobuono- Battisti,2014, ApJ; Mastrobuono-Battisti, Perets & Loeb, 2016, ApJ; Tsatsi, Mastrobuono-Battisti et al., 2016, MNRAS

10 GCs decay and merge, forming the NSC: models based on Milky Way data y(pc) 0 z(pc) x (pc) 12 GCs, initially at 20pc 1.1x10 6 M each ~800Myr between each infall x (pc) Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt (2012); Perets & Mastrobuono-Battisti (2014)

11 GCs decay and merge, forming the NSC: models based on Milky Way data y(pc) 0 z(pc) x (pc) 12 GCs, initially at 20pc 1.1x10 6 M each ~800Myr between each infall x (pc) Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt (2012); Perets & Mastrobuono-Battisti (2014)

12 GCs decay and merge, forming the NSC: snapshots 1st 2nd 3rd 4th 4th 6th 7th 8th 9th 10th 11th 12th Antonini, Capuzzo-Dolcetta, Mastrobuono-Battisti & Merritt 2012,

13 The infall scenario forms an NSC with a large core-like structure #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

14 The infall scenario forms an NSC with a large core-like structure #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

15 The infall scenario forms an NSC with a large core-like structure #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

16 The infall scenario forms an NSC with a large core-like structure Gyr #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

17 The infall scenario forms an NSC with a large core-like structure Gyr #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

18 The infall scenario forms an NSC with a large core-like structure Gyr 3 10Gyr #infalls Antonini et al. 2012, Mastrobuono Battisti et al. 2014, Perets & MB 2014

19 The Milky Way s is the closest NSC MNSC ~10 7 M Schödel (2010) It hosts a massive BH: Sgr A* MBH = M (Genzel et al. 2010; Ghez et al. 2008; Gillessen et al. 2009; Eisenhauer et al. 2005) Tangentially anisotropic, : (Merritt 2010). Flattened with q = 0.71±0.02 (Schödel et al. 2014).

20 The Milky Way s is the closest NSC MNSC ~10 7 M It hosts a massive BH: Sgr A* MBH = M (Genzel et al. 2010; Ghez et al. 2008; Gillessen et al. 2009; Eisenhauer et al. 2005) Tangentially anisotropic, : (Merritt 2010). Flattened with q = 0.71±0.02 (Schödel et al. 2014).

21 The Milky Way s is the closest NSC MNSC ~10 7 M 10Gyr It hosts a massive BH: Sgr A* MBH = M (Genzel et al. 2010; Ghez et al. 2008; Gillessen et al. 2009; Eisenhauer et al. 2005) Tangentially anisotropic, : (Merritt 2010). Flattened with q = 0.71±0.02 (Schödel et al. 2014).

22 Simulations vs Observations: Direct comparison with the Milky Way NSC

23 What do we learn from observations? arcsec ν arcsec σ arcsec arcsec arcsec 1pc ~ 26 Feldmeier arcsec

24 We can get similar maps for the simulated cluster

25 We can get similar maps for the simulated cluster

26 We can get similar maps for the simulated cluster

27 We can get similar maps for the simulated cluster

28 The real and simulated NSC look similar arcsec arcsec arcsec 1pc ~ 26 arcsec arcsec arcsec

29 The real and simulated NSC look similar arcsec arcsec arcsec 1pc ~ 26 arcsec arcsec arcsec

30 The similarity is apparent from radial plots

31 The similarity is apparent from radial plots Feldmeier arcsec arcsec

32 The similarity is apparent from radial plots Feldmeier arcsec arcsec

33 The similarity is apparent from radial plots Feldmeier arcsec arcsec Tsatsi, Mastrobuono-Battisti et al. 2017

34 The similarity is apparent from radial plots

35 The similarity is apparent from radial plots Feldmeier arcsec arcsec

36 The similarity is apparent from radial plots Feldmeier arcsec arcsec

37 The similarity is apparent from radial plots Feldmeier arcsec arcsec Tsatsi, Mastrobuono-Battisti et al. 2017

38 The similarity is apparent from radial plots Feldmeier arcsec arcsec Tsatsi, Mastrobuono-Battisti et al. 2017

39 Which role has the bulge?

40 Which role has the bulge?

41 Kinematic profiles are still consistent

42 Can we predict kinematic substructures? 60 V model 80 arcsec arcsec arcsec V data arcsec Velocity [km/s] Velocity [km/s] Fig. 8. Upper panel: kinemetric model velocity map of the cleaned data cube. Black dots denote Feldmeier the best fitting et ellipses. al The model goes only to r along the Galactic plane and to perpendicular to it. The

43 Can we predict kinematic substructures? Feldmeier+2014 Tsatsi, Mastrobuono-Battisti et al., 2017

44 Can we predict kinematic substructures? Feldmeier+2014 Kinemetry (Krajnovic +2006) Tsatsi, Mastrobuono-Battisti et al., 2017

45 Can we predict kinematic substructures? Feldmeier+2014 Kinemetry (Krajnovic +2006) Created by a polar merger Tsatsi, Mastrobuono-Battisti et al., 2017

46 Can we predict kinematic substructures? Feldmeier+2014 Kinemetry (Krajnovic +2006) Created by a polar merger Tsatsi, Mastrobuono-Battisti et al., 2017

47 Can we predict kinematic substructures? Feldmeier+2014 Kinemetry (Krajnovic +2006) Created by a polar merger Tsatsi, Mastrobuono-Battisti et al., 2017

48 The effect of IMBHs on the formation and evolution of NSCs

49 IMBHs may be present in dense clusters and decay with them Silk & Arons (1975): massive clusters may host an IMBH at their center: The merging model implies the presence of IMBHs in NSCs. Orbital radius of the last IMBH to fall in The other 11 IMBHs We introduced an IMBH in each GC Mastrobuono-Battisti et al., 2014

50 The presence of IMBHs causes the NSC to have a steep cusp and to be strongly mass segregated without IMBHs with IMBHs Mastrobuono-Battisti et al., 2014

51 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss

52 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss

53 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss

54 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss Komossa 2012; Khabibullin & Sazonov 2014

55 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss Komossa 2012; Khabibullin & Sazonov 2014

56 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss Komossa 2012; Khabibullin & Sazonov 2014

57 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss Komossa 2012; Khabibullin & Sazonov 2014

58 We can estimate the tidal disruption events rate Image credit: NASA/CXC/ M.Weiss Komossa 2012; Khabibullin & Sazonov 2014 No IMBHs in NSCs?

59 Conclusions

60 Conclusions N-body simulations to study the merger scenario

61 Conclusions N-body simulations to study the merger scenario Direct comparison with the Milky Way NSC: mock observational maps

62 Conclusions N-body simulations to study the merger scenario Direct comparison with the Milky Way NSC: mock observational maps The infall scenario reproduces most of the properties of the MW NSC, including its rotation

63 Conclusions N-body simulations to study the merger scenario Direct comparison with the Milky Way NSC: mock observational maps The infall scenario reproduces most of the properties of the MW NSC, including its rotation We also find kinematic substructures similar to the observed one: the infall scenario is really plausible!

64 Conclusions N-body simulations to study the merger scenario Direct comparison with the Milky Way NSC: mock observational maps The infall scenario reproduces most of the properties of the MW NSC, including its rotation We also find kinematic substructures similar to the observed one: the infall scenario is really plausible! No IMBHs in NSCss? more observations needed!

65 Conclusions N-body simulations to study the merger scenario Direct comparison with the Milky Way NSC: mock observational maps The infall scenario reproduces most of the properties of the MW NSC, including its rotation We also find kinematic substructures similar to the observed one: the infall scenario is really plausible! No IMBHs in NSCss? more observations needed! Can we predict chemical properties? (Leaman, MB, work in prog.)

66 Thank you!

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