35 research outputs found
A Far-Ultraviolet View of Starburst Galaxies
Recent observational and theoretical results on starburst galaxies related to
the wavelength regime below 1200 A are discussed. The review covers stars,
dust, as well as hot and cold gas. This wavelength region follows trends
similar to those seen at longer wavelengths, with several notable exceptions.
Even the youngest stellar populations show a turn-over in their spectral energy
distributions, and line-blanketing is much more pronounced. Furthermore, the O
VI line allows one to probe gas at higher temperatures than possible with lines
at longer wavelengths. Molecular hydrogen lines (if detected) provide a glimpse
of the cold phase. I cover the crucial wavelength regime below 912 A and the
implications of recent attempts to detect the escaping ionizing radiation.Comment: 8 pages, 3 figures, Invited Talk, Starbursts--From 30 Doradus to
Lyman-Break Galaxies, ed. R. de Grijs & R. M. Gonzalez Delgado (Dordrecht:
Kluwer
The Fueling and Evolution of AGN: Internal and External Triggers
In this chapter, I review the fueling and evolution of active galactic nuclei
(AGN) under the influence of internal and external triggers, namely intrinsic
properties of host galaxies (morphological or Hubble type, color, presence of
bars and other non-axisymmetric features, etc) and external factors such as
environment and interactions. The most daunting challenge in fueling AGN is
arguably the angular momentum problem as even matter located at a radius of a
few hundred pc must lose more than 99.99 % of its specific angular momentum
before it is fit for consumption by a BH. I review mass accretion rates,
angular momentum requirements, the effectiveness of different fueling
mechanisms, and the growth and mass density of black BHs at different epochs. I
discuss connections between the nuclear and larger-scale properties of AGN,
both locally and at intermediate redshifts, outlining some recent results from
the GEMS and GOODS HST surveys.Comment: Invited Review Chapter to appear in LNP Volume on "AGN Physics on All
Scales", Chapter 6, in press. 40 pages, 12 figures. Typo in Eq 5 correcte
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Active Galactic Nuclei at the Crossroads of Astrophysics
Over the last five decades, AGN studies have produced a number of spectacular
examples of synergies and multifaceted approaches in astrophysics. The field of
AGN research now spans the entire spectral range and covers more than twelve
orders of magnitude in the spatial and temporal domains. The next generation of
astrophysical facilities will open up new possibilities for AGN studies,
especially in the areas of high-resolution and high-fidelity imaging and
spectroscopy of nuclear regions in the X-ray, optical, and radio bands. These
studies will address in detail a number of critical issues in AGN research such
as processes in the immediate vicinity of supermassive black holes, physical
conditions of broad-line and narrow-line regions, formation and evolution of
accretion disks and relativistic outflows, and the connection between nuclear
activity and galaxy evolution.Comment: 16 pages, 5 figures; review contribution; "Exploring the Cosmic
Frontier: Astrophysical Instruments for the 21st Century", ESO Astrophysical
Symposia Serie
"Tomography" of the cluster structure of light nuclei via relativistic dissociation
These lecture notes present the capabilities of relativistic nuclear physics
for the development of the physics of nuclear clusters. Nuclear track emulsion
continues to be an effective technique for pilot studies that allows one, in
particular, to study the cluster dissociation of a wide variety of light
relativistic nuclei within a common approach. Despite the fact that the
capabilities of the relativistic fragmentation for the study of nuclear
clustering were recognized quite a long time ago, electronic experiments have
not been able to come closer to an integrated analysis of ensembles of
relativistic fragments. The continued pause in the investigation of the "fine"
structure of relativistic fragmentation has led to resumption of regular
exposures of nuclear emulsions in beams of light nuclei produced for the first
time at the Nuclotron of the Joint Institute for Nuclear Research (JINR,
Dubna). To date, an analysis of the peripheral interactions of relativistic
isotopes of beryllium, boron, carbon and nitrogen, including radioactive ones,
with nuclei of the emulsion composition, has been performed, which allows the
clustering pattern to be presented for a whole family of light nuclei.Comment: ISBN 978-3-319-01076-2. 55 pages, 28 figure
Galaxy bulges and their massive black holes: a review
With references to both key and oft-forgotten pioneering works, this article
starts by presenting a review into how we came to believe in the existence of
massive black holes at the centres of galaxies. It then presents the historical
development of the near-linear (black hole)-(host spheroid) mass relation,
before explaining why this has recently been dramatically revised. Past
disagreement over the slope of the (black hole)-(velocity dispersion) relation
is also explained, and the discovery of sub-structure within the (black
hole)-(velocity dispersion) diagram is discussed. As the search for the
fundamental connection between massive black holes and their host galaxies
continues, the competing array of additional black hole mass scaling relations
for samples of predominantly inactive galaxies are presented.Comment: Invited (15 Feb. 2014) review article (submitted 16 Nov. 2014). 590
references, 9 figures, 25 pages in emulateApJ format. To appear in "Galactic
Bulges", E. Laurikainen, R.F. Peletier, and D.A. Gadotti (eds.), Springer
Publishin
Probing evolutionary population synthesis models in the near infrared with early-type galaxies
We performed a near-infrared (NIR; ~1.0 -2.4 μm) stellar population study in a sample of early-type galaxies. The synthesis was performed using five different evolutionary population synthesis libraries of models. Our main results can be summarized as follows: low-spectral-resolution libraries are not able to produce reliable results when applied to the NIR alone, with each library finding a different dominant population. The two newest higher resolution models, on the other hand, perform considerably better, finding consistent results to each other and to literature values. We also found that optical results are consistent with each other even for lower resolution models. We also compared optical and NIR results and found out that lower resolution models tend to disagree in the optical and in the NIR, with higher fraction of young populations in the NIR and dust extinction ~1 mag higher than optical values. For higher resolution models, optical and NIR results tend to agree much better, suggesting that a higher spectral resolution is fundamental to improve the quality of the results.© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.LGDH thanks CAPES and CNPq. RR thanks CNPq and FAPERGS for partial funding of this project. ARA thanks CNPq for partial support to this work. LPM thanks CNPQ and FAPESP for partial funding of this project. CK acknowledges support through the research project AYA2017-79724-C4-4-P from the Spanish PNAYA. This research made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This study uses data provided by the Calar Alto Legacy Integral Field Area (CALIFA) survey (http://califa.caha.es/). Based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut fur Astronomie and the Instituto de Astrofisica de Andalucia (CSIC). We thank the referee Reynier Peletier for carefully reading our paper and for giving such constructive comments which substantially helped improving the quality of the paper