Possible Signatures of a Cold-Flow Disk from MUSE using a z=1 galaxy--quasar pair towards SDSSJ1422-0001

We use a background quasar to detect the presence of circum-galactic gas around a $z=0.91$ low-mass star forming galaxy. Data from the new Multi Unit Spectroscopic Explorer (MUSE) on the VLT show that the host galaxy has a dust-corrected star-formation rate (SFR) of 4.7$\pm$0.2 Msun/yr, with no companion down to 0.22 Msun/yr (5 $\sigma$) within 240 kpc (30"). Using a high-resolution spectrum (UVES) of the background quasar, which is fortuitously aligned with the galaxy major axis (with an azimuth angle $\alpha$ of only $15^\circ$), we find, in the gas kinematics traced by low-ionization lines, distinct signatures consistent with those expected for a "cold flow disk" extending at least 12 kpc ($3\times R_{1/2}$). We estimate the mass accretion rate $\dot M_{\rm in}$ to be at least two to three times larger than the SFR, using the geometric constraints from the IFU data and the HI column density of $\log N_{\rm HI} \simeq 20.4$ obtained from a {\it HST}/COS NUV spectrum. From a detailed analysis of the low-ionization lines (e.g. ZnII, CrII, TiII, MnII, SiII), the accreting material appears to be enriched to about 0.4 $Z_\odot$ (albeit with large uncertainties: $\log Z/Z_\odot=-0.4~\pm~0.4$), which is comparable to the galaxy metallicity ($12+\log \rm O/H=8.7\pm0.2$), implying a large recycling fraction from past outflows. Blue-shifted MgII and FeII absorptions in the galaxy spectrum from the MUSE data reveal the presence of an outflow. The MgII and FeII doublet ratios indicate emission infilling due to scattering processes, but the MUSE data do not show any signs of fluorescent FeII* emission.Comment: 17 pages, 11 figures, in press (ApJ), minor edits after the proofs. Data available at http://muse-vlt.eu/science/j1422

Gas Accretion in Star-Forming Galaxies

Cold-mode gas accretion onto galaxies is a direct prediction of LCDM simulations and provides galaxies with fuel that allows them to continue to form stars over the lifetime of the Universe. Given its dramatic influence on a galaxy's gas reservoir, gas accretion has to be largely responsible for how galaxies form and evolve. Therefore, given the importance of gas accretion, it is necessary to observe and quantify how these gas flows affect galaxy evolution. However, observational data have yet to conclusively show that gas accretion ubiquitously occurs at any epoch. Directly detecting gas accretion is a challenging endeavor and we now have obtained a significant amount of observational evidence to support it. This chapter reviews the current observational evidence of gas accretion onto star-forming galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springer. This chapter includes 22 pages with 7 Figure

A far-ultraviolet-driven photoevaporation flow observed in a protoplanetary disk.

Most low-mass stars form in stellar clusters that also contain massive stars, which are sources of far-ultraviolet (FUV) radiation. Theoretical models predict that this FUV radiation produces photodissociation regions (PDRs) on the surfaces of protoplanetary disks around low-mass stars, which affects planet formation within the disks. We report James Webb Space Telescope and Atacama Large Millimeter Array observations of a FUV-irradiated protoplanetary disk in the Orion Nebula. Emission lines are detected from the PDR; modeling their kinematics and excitation allowed us to constrain the physical conditions within the gas. We quantified the mass-loss rate induced by the FUV irradiation and found that it is sufficient to remove gas from the disk in less than a million years. This is rapid enough to affect giant planet formation in the disk

Reproduzierbarkeit und Aufloesungsvermoegen faseroptischer Temperaturmessungen fuer Bohrlochanwendungen Untersuchungen in der Klimakammer des GFZ

SIGLEAvailable from TIB Hannover: RR 6134(99/19) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Understanding the environment around the intermediate mass black hole candidate ESO 243-49 HLX-1

Aims. ESO 243-49 HLX-1, otherwise known as HLX-1, is an intermediate mass black hole (IMBH) candidate located 8′′ (3.7 Kpc) from the centre of the edge-on S0 galaxy ESO 243-49. How the black hole came to be associated with this galaxy, and the nature of the environment in which it resides, remain unclear. Using multi-wavelength observations we aim to investigate the nature of the medium surrounding HLX-1, search for evidence of past mergers with ESO 243-49 and constrain parameters of the galaxy, including the mass of the expected central supermassive black hole, essential for future modelling of the interaction of the IMBH and ESO 243-49. Methods. We have reduced and analysed integral field unit observations of ESO 243-49 that were taken with the MUSE instrument on the VLT. Using complementary multi-wavelength data, including X-shooter, HST, Swift, Chandra and ATCA data, we have further examined the vicinity of HLX-1. We additionally examined the nature of the host galaxy and estimate the mass of the central supermassive black hole in ESO 243-49 using (black hole mass)–(host spheroid) scaling relations and the fundamental plane of black hole activity. Results. No evidence for a recent minor-merger that could result in the presence of the IMBH is discerned, but the data are compatible with a scenario in which minor mergers may have occurred in the history of ESO 243-49. The MUSE data reveal a rapidly rotating disc in the centre of the galaxy, around the supermassive black hole. The mass of the supermassive black hole at the centre of ESO 243-49 is estimated to be 0.5−23 × 107M⊙. Studying the spectra of HLX-1, that were taken in the low and hard state, we determine Hα flux variability to be at least a factor 6, compared to observations taken during the high and soft state. This Hα flux variability over one year indicates that the line originates close to the intermediate mass black hole, excluding the possibility that the line emanates from a surrounding nebula or a star cluster. The large variability associated with the X-ray states of HLX-1 confirms that the Hα line is associated with the object and therefore validates the distance to HLX-1

POSSIBLE SIGNATURES of A COLD-FLOW DISK from MUSE USING A z ∼ 1 GALAXY-QUASAR PAIR TOWARD SDSS J1422-0001

We use a background quasar to detect the presence of circumgalactic gas around a z = 0.91 low-mass star-forming galaxy. Data from the new Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope show that the galaxy has a dust-corrected star formation rate (SFR) of 4.7 ± 2.0 M⊙ yr-1, with no companion down to 0.22 M⊙ yr-1 (5σ) within 240 h-1 kpc ("30"). Using a high-resolution spectrum of the background quasar, which is fortuitously aligned with the galaxy major axis (with an azimuth angle α of only 15°), we find, in the gas kinematics traced by low-ionization lines, distinct signatures consistent with those expected for a "cold-flow disk" extending at least 12 kpc (3 × R1/2). We estimate the mass accretion rate Ṁin to be at least two to three times larger than the SFR, using the geometric constraints from the IFU data and the H I column density of log NH I/cm-2 ≃ 20.4 obtained from a Hubble Space Telescope/COS near-UV spectrum. From a detailed analysis of the lowionization lines (e.g., Zn II, Cr II, Ti II, Mn II, Si II), the accreting material appears to be enriched to about 0.4 Z⊙ (albeit with large uncertainties: log Z/Z⊙ = -0.4 ± 0.4), which is comparable to the galaxy metallicity (12 + log O/H = 8.7 ± 0.2), implying a large recycling fraction from past outflows. Blueshifted Mg II and Fe II absorptions in the galaxy spectrum from the MUSE data reveal the presence of an outflow. The Mg II and Fe II absorption line ratios indicate emission infilling due to scattering processes, but the MUSE data do not show any signs of fluorescent Fe II∗ emission