TEREZA JEŘÁBKOVÁ ESO GARCHING & UNIVERSITY OF BONN & CHARLES UNIVERSITY IN PRAGUE

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1 1 TEREZA JEŘÁBKOVÁ ESO GARCHING & UNIVERSITY OF BONN & CHARLES UNIVERSITY IN PRAGUE www: sirrah.troja.mff.cuni.cz/~tereza 17 MODEST UNDER PRAGUE S STARRY SKIES CZECH REPUBLIC OF SEPTEMBER 2017 STELLAR POPULATIONS IN EXTREME STAR BURST CLUSTERS AND ULTRA-COMPACT DWARF GALAXIES (UCD s) TH

2 MOTIVATION STELLAR POPULATIONS WHAT WE CAN SEE NEARBY? 2 Galactic star forming regions similar environments ( %, T,... ) and basically solar metallicity we observe very young objects (formation snapshot) BUT at similar initial conditions it is difficult to study environmental dependencies of star formation and stellar IMF s

3 MOTIVATION STELLAR POPULATIONS WHAT WE CAN SEE NEARBY? 3 Galactic star forming regions similar environments ( %, T,... ) and basically solar metallicity we observe very young objects (formation snapshot) BUT at similar initial conditions it is difficult to study environmental dependencies of star formation and stellar IMF Older objects - Galactic star clusters and GCs and extragalactic UCDs most likely formed under different physical conditions compared to local star formation BUT highly evolved systems degenerate with age (initial conditions?) we observe only low mass stars and dynamically evolved systems s s

4 MOTIVATION STELLAR POPULATIONS WHAT WE CAN SEE NEARBY? 4 Galactic star forming regions similar environments ( %, T,... ) and basically solar metallicity we observe very young objects (formation snapshot) BUT at similar initial conditions it is difficult to study environmental dependencies of star formation and stellar IMF Older objects - Galactic star clusters and GCs and extragalactic UCDs most likely formed under different physical conditions compared to local star formation BUT highly evolved systems degenerate with age we observe only low mass stars and dynamically evolved systems QUESTION: CAN WE OBSERVE PROGENITORS OF GC s AND UCD s?

5 LAYOUT OF THE PROJECT 5 see also (Renzini,A&A,2017) see e.g Glazebrook+(2017,Nat.) & Vanzella+(2017,MNRAS) Aim: How extreme star formation environments may appear at high redshifts. (Predictions of observables with James Web Space Telescope) 1. Construction of stellar population models for progenitors of UCDs and GCs Using PEGASE code (Fioc & Rocca-Volmerange 1997) 2. Computation of photometric (magnitudes, colours) and other (SN rates, spectral slopes) diagnostics With underlying question: Can a systematic variation of the stellar IMF in massive star-bursts be confirmed using observations with the JWST? + potential for constraining the formation of multiple stellar populations

6 ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE 1. Assumption: UCDs and GCs form by monolithic collapse (At least some need to Jerabkova +, A&A, 2017) + formation channel through merged star cluster complexes can be constrained 2. Assumption: Red-shift computed based on CDM and Planck data (Planck Collaboration +, 2016a,b) redshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang) 3. Assumption: General shape of the IMF: multi-power law Canonical IMF - nearby star forming regions (Kroupa 2001) - green in all plots 2 6 log (m)[relative] =1.3 2 =2.3 3 =2.3 Salpeter slope =2.3 canonical IMF log (m [M ])

7 ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE 7 1. Assumption: UCDs and GCs form by monolithic collapse (At least some need to Jerabkova +, A&A, 2017) + formation channel through merged star cluster complexes can be constrained 2. Assumption: Red-shift computed based on CDM and Planck data (Planck Collaboration +, 2016a,b) redshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang) 3. Assumption: General shape of the IMF: multi-power law Canonical IMF - nearby star forming regions (Kroupa 2001) - green in all plots Top-heavy IMF if: large densities, small [Fe/H] Larson (1998), Adams+(1996), Dib+(2007), Papadopoulos (20) Dabringhausen 2009&20,Marks+2012, Kirk+2012, Zonoozi+2016, Haghi+2017,Romano+(2017) Bottom-heavy IMF if: metal rich (Marks+2012) large densities (Conroy & van Dokkum) log (m)[relative] centres of ellipticals Chabrier+(2014) - increased density leads to bottom heavy IMF BUT potential problems: Bertelli Motta+(2016), Liptai+(2017) BOTTOM-HEAVY 1 =1.3 2 =2.3 more massive stars per cluster mass TOP-HEAVY 3 =2.3 Salpeter slope canonical IMF log (m [M ])

8 ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE 8 1. Assumption: UCDs and GCs form by monolithic collapse (At least some need to Jerabkova +, A&A, 2017) + formation channel through merged star cluster complexes can be constrained 2. Assumption: Red-shift computed based on CDM and Planck data (Planck Collaboration +, 2016a,b) redshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang) 3. Assumption: General shape of the IMF: multi-power law Canonical IMF - nearby star forming regions (Kroupa 2001) - green in all plots BOTTOM-HEAVY 2 1 =1.3, 2 = 3 =2.3 Top-heavy IMF 3 < 2.3 varies with initial conditions Marks+(2012), Bottom-heavy IMF 1 = 2 = 3 =2.3 Dabringhausen+(2008), SAL IMF 1 = 2 = 3 =3.0 log (m)[relative] van Dokkum&Conroy+(20), =1.3 2 =2.3 more massive stars per cluster mass TOP-HEAVY 3 =2.3 Salpeter slope canonical IMF log (m [M ])

9 ASSUMPTIONS & PARAMETRISATION OF THE STAR CLUSTER SPACE 9 1. Assumption: UCDs and GCs form by monolithic collapse (At least some need to Jerabkova +, A&A, 2017) + formation channel through merged star cluster complexes can be constrained 2. Assumption: Red-shift computed based on CDM and Planck data (Planck Collaboration +, 2016a,b) redshift considered: z=0,3,6,9 (13.5, 2.1, 0.9, 0.6 Gyr after Big-Bang) 3. Assumption: General shape of the IMF: multi-power law SAL IMF Kroupa(2001) Marks+(2012) Dabringhausen+(2008) van Dokkum&Conroy+(20) 4. Assumption: other parameters time grid: (1- Myr, -0 Myr, 0-00 Myr, 1-13 Gyr) initial stellar masses:, SFE = 0.33 [Fe/H] = -2, 0 6, 7, 8, 9 M Megeath+(2016), Banerjee(2017) Star formation history: simultaneous, constant over 5- Myr PEGASE time-dependent stellar population synthesis code Fioc&Rocca-Volmerange(1997) (comparison with SB99)

10 RESULTS For the introduced parameters we construct a grid of SEDs which allow us to construct observables and other characteristic. Luminosity, color-(color)magnitude diagrams, SED slopes Mass-to-light ratios, supernovae rates for each set of parameters For the first time we predict how the progenitors of UCDs and massive GCs might look like when formed at high redshifts and compute observability with the JWST. MKD IMF F [(ergs 1 cm 2 Hz 1 )] 11 12? 20Myr Marks et al. (2012) [Å] 6Myr 7Myr 8Myr 9Myr Myr 20Myr [Å] 6Myr 7Myr 8Myr 9Myr Myr mk mn Gyr z=9 zoomed plot m J m K log (time [Myr]) J and K filter cover similar wavelength range as F115W and F200W (NIRCam) N filter covers similar wavelength range as F00W (MIRI)

11 RESULTS: BOLOMETRIC LUMINOSITY 11 As bright as quasars! Supernova explosions may cause photometric variability Degeneracies 12 M UCD = 8 M L bol à M UCD (NOT for MKDP) QUASARS 25.0 Lbol [L ] M [Fe/H]= 2 [Fe/H]= 0 SUPERNOVAE Mbol [mag] larger stellar mass top-heavy IMF age of the system SAL IMF 8 M 7 M time [Myr] UCD DATA Consistency check

12 RESULTS: COLOR-MAGNITUDE DIAGRAM 12 Also colours can be consistent with QSO! 25 QUASARS 25 QUASARS [Fe/H]=0 [Fe/H]= 2 20 time 20 time MV MV 15 9 M 8 M 7 M 15 UCD data M V M Ic 9 M 8 M 7 M M V M Ic dots/squares: 0 Myr, 500 Myr, 1 Gyr, 5 Gyr, Gyr QSO data: Dunlop+(1993),Dunlop+(2003),Souchay+(2015) high redshift quasars: Morltlock+(2011)

13 % remnants time [Myr] 3 7 M 8 M 9 M [Fe/H]=0 4 See our paper (Jerabkova+2017) 0% remnants % remnants NO remnants 3 4 SN kicks are not able to remove large fraction of BHs 1 2 % remnants NO remnants 3 SAL IMF 1 MBH ø 0 SAL IMF 7 M 8 M 9 M [Fe/H]=-2 MBH ø 1 M/LV M/LV RESULTS: MASS-TO-LIGHT RATIOS time [Myr] 3 4 and poster: The black hole retention fraction in star clusters (P2) no degeneracies, t < 0 Myr

14 % remnants time [Myr] 3 7 M 8 M 9 M [Fe/H]=0 4 % remnants NO remnants time [Myr] 3 M/LV SAL IMF 5 Gyr Gyr 13 Gyr [Fe/H]= MV [mag] [Fe/H]= 0 20 M/LV LV [LV ] 8 4 and poster: The black hole retention fraction in star clusters (P2) no degeneracies, t < 0 Myr 9, 8, 7 M MV [mag] See our paper (Jerabkova+2017) 0% remnants 3 4 SN kicks are not able to remove large fraction of BHs 1 2 % remnants NO remnants 3 SAL IMF 1 MBH ø 0 SAL IMF 7 M 8 M 9 M [Fe/H]=-2 MBH ø 1 M/LV M/LV RESULTS: MASS-TO-LIGHT RATIOS 6 observations 7 LV [LV ] 8 Results are sensitive to [Fe/H]

15 RESULTS: SUMMARY AND CONCLUSIONS Progenitors of UCDs and massive GCs are observable with JWST 2. For objects younger than 0 Myr we can constrain their IMF ( if we observe them) 3. Older objects suffer from degeneracies and constraining the IMF is more difficult 4. Some observed quasars have similar photometric properties as very young UCDs with top-heavy IMF (Are all quasars quasars?) 5. The kick retention fraction of stellar remnants is near to 0% for systems with birth masses larger than 7 M In prep.: Similar analysis aiming at multiple populations in young GCs Can we disentangle different formation scenarios? What is the effect of binaries? See also: Bekki, Jerabkova, Kroupa, MNRAS, 2017 (variable IMF in GCs) and: Yan, Jerabkova, Kroupa, A&A, 2017 (systematic variation of the IMF in python - on Github)

16 z=3 RESULTS: REDSHIFTED SED 16 J and K filter cover similar wavelength range as F115W and F200W (NIRCam) N filter covers similar wavelength range as F00W (MIRI) 30 8 Myr 8 Myr MKD IMF F [(ergs 1 cm 2 Hz 1 )] z=6 z=9 z=3 z=6 z=9 33 J filt. K filt. N filt. J filt. K filt. N filt [Å] [Å]

17 RESULTS: FORMATION AND WHERE TO LOOK 17 The most massive clusters are near the centres of galaxies with high star formation rate Ferrarese&Merritt (2002), Dabringhausen+(2012), Weidner+(2004), Randriamanakoto+(2013),Li+(2017) Possible formation scenario 1. Formation of massive galaxies - large star formation rates (large densities, merging of proto-galactic gas clumps) 2. The most massive clusters are forming as monolithically collapsed in the deepest potential wells of these (decouple from gas when become stellar systems) 3. Merging proto-galaxies - many formed clusters ending up on orbits about the central galaxy 4. Under more benign conditions we expect to form stellar systems from mergers of star cluster complexes