How AGN feedback drives the size growth of the first quasars

Quasars at $z \,=\, 6$ are powered by accretion onto supermassive black holes with masses $M_{\rm BH} \sim 10^9 \rm \, M_{\odot}$. Their rapid assembly requires efficient gas inflow into the galactic nucleus, sustaining black hole accretion at a rate close to the Eddington limit, but also high central star formation rates. Using a set of cosmological 'zoom-in' hydrodynamic simulations performed with the moving mesh code Arepo, we show that $z \,=\, 6$ quasar host galaxies develop extremely tightly bound stellar bulges with peak circular velocities $300$ - $500$ km s$^{-1}$ and half-mass radii $\approx 0.5 \, \rm kpc$. Despite their high binding energy, we find that these compact bulges expand at $z \, < \, 6$, with their half-mass radii reaching $\approx 5$ kpc by $z \, = \, 3$. The circular velocity drops by factors $\approx 2$ from their initial values to $200$ - $300$ km s$^{-1}$ at $z \, \approx \, 3$ and the stellar profile undergoes a cusp-core transformation. By tracking individual stellar populations, we find that the gradual expansion of the stellar component is mainly driven by fluctuations in the gravitational potential induced by bursty AGN feedback. We also find that galaxy size growth and the development of a cored stellar profile does not occur if AGN feedback is ineffective. Our findings suggest that AGN-driven outflows may have profound implications for the internal structure of massive galaxies, possibly accounting for their size growth, the formation of cored ellipticals as well as for the saturation of the $M_{\rm BH}$ - $\sigma_{\star}$ seen at high velocity dispersions $\sigma_{\star}$.Comment: 17 pages, 11 figures, 2 tables, accepted for publication in MNRA

Measuring the Milky Way in M-dwarfs

We report 274 M-dwarfs found in the Brightest of Reionizing Galaxies (BoRG) survey for high redshift galaxies. Using these, we fitted a model for the disk and halo with a fixed scale length at h = 2.6 kpc. We found a scale height z0 of 0.60±0.03 kpc, flattening parameter κ of 0.45±0.04 and a powerlaw-index p of 2.4±0.07. For the total number of M-dwarfs in the disk and halo we found 26.7_(-6.2)^(+9.3)×10^9. The upper limit for the halo fraction of M-dwarfs in the halo is 7_(-4)^(+5) %. The total mass upper limit was determined to be 1.99_(-0.5)^(+0.73)×10^9 Solar masses

The size and shape of the Milky Way disc and halo from M-type brown dwarfs in the BoRG survey.

We have identified 274 M-type brown dwarfs in the Hubble Space Telescope\u27s Wide Field Camera 3 pure parallel fields from the Brightest of Reionizing Galaxies (BoRG) survey for high-redshift galaxies. These are near-infrared observations with multiple lines of sight out of our Milky Way. Using these observed M-type brown dwarfs, we fitted a Galactic disc and halo model with a Markov chain Monte Carlo analysis. This model worked best with the scalelength of the disc fixed at h = 2.6 kpc. For the scaleheight of the disc, we found z0=0.29+0.02−0.019 z0=0.29−0.019+0.02 kpc and for the central number density, ρ0=0.29+0.20−0.13 ρ0=0.29−0.13+0.20 # pc−3. For the halo, we derived a flattening parameter κ = 0.45 ± 0.04 and a power-law index p = 2.4 ± 0.07. We found the fraction of M-type brown dwarfs in the local density that belong to the halo to be fh = 0.0075 +0.0025−0.0019 −0.0019+0.0025 . We found no correlation between subtype of M-dwarf and any model parameters. The total number of M-type brown dwarfs in the disc and halo was determined to be 58.2+9.81−6.70×109 58.2−6.70+9.81×109 . We found an upper limit for the fraction of M-type brown dwarfs in the halo of 7 +5−4 −4+5  per cent. The upper limit for the total Galactic disc mass in M-dwarfs is 4.34+0.73−0.5×109 4.34−0.5+0.73×109 M⊙, assuming all M-type brown dwarfs have a mass of 80 MJ

CCDC 1429820: Experimental Crystal Structure Determination

XAJNII : Chloro-(2,4-di-t-butyl-6-((2-(diphenylphosphino)phenyl)amino)phenol)-gold(i) chloroform solvate Space Group: P 1 (2), Cell: a 9.6157(4)Å b 9.7984(4)Å c 20.5321(9)Å, α 85.875(2)° β 79.286(2)° γ 63.703(2)° Related Article: Daniël L. J. Broere, Dieuwertje K. Modder, Eva Blokker, Maxime A. Siegler and Jarl Ivar van der Vlugt|2016|Angew.Chem.,Int.Ed.|55|2406|doi:10.1002/anie.201509412,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 1429114: Experimental Crystal Structure Determination

XAJNEE : bis(μ2-2,4-Di-t-butyl-6-((2-(diphenylphosphino)phenyl)imino)cyclohexa-2,4-dien-1-olato radical)-gold-nickel hexafluorophosphate deuteroacetonitrile solvate Space Group: P b c a (61), Cell: a 15.6769(3)Å b 25.6953(6)Å c 31.0221(6)Å, α 90° β 90° γ 90° Related Article: Daniël L. J. Broere, Dieuwertje K. Modder, Eva Blokker, Maxime A. Siegler and Jarl Ivar van der Vlugt|2016|Angew.Chem.,Int.Ed.|55|2406|doi:10.1002/anie.201509412,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 1429112: Experimental Crystal Structure Determination

XAJMUT : bis(μ2-2,4-Di-t-butyl-6-((2-(diphenylphosphino)phenyl)imino)cyclohexa-2,4-dien-1-olato radical)-dichloro-di-gold-nickel dichloromethane solvate Space Group: P 1 (2), Cell: a 9.4197(3)Å b 13.4681(3)Å c 13.5232(3)Å, α 89.3981(19)° β 88.130(2)° γ 71.941(2)° Related Article: Daniël L. J. Broere, Dieuwertje K. Modder, Eva Blokker, Maxime A. Siegler and Jarl Ivar van der Vlugt|2016|Angew.Chem.,Int.Ed.|55|2406|doi:10.1002/anie.201509412,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 1429113: Experimental Crystal Structure Determination

XAJNAA : bis(μ2-2,4-Di-t-butyl-6-((2-(diphenylphosphino)phenyl)imino)cyclohexa-2,4-dien-1-olato radical)-dibromo-di-gold-nickel tetrahydrofuran solvate Space Group: P 21/c (14), Cell: a 13.4429(4)Å b 14.7209(5)Å c 18.3728(5)Å, α 90° β 106.793(3)° γ 90° Related Article: Daniël L. J. Broere, Dieuwertje K. Modder, Eva Blokker, Maxime A. Siegler and Jarl Ivar van der Vlugt|2016|Angew.Chem.,Int.Ed.|55|2406|doi:10.1002/anie.201509412,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.