scholarly journals X-ray detected AGN in SDSS dwarf galaxies

2020 ◽  
Vol 492 (2) ◽  
pp. 2268-2284 ◽  
Author(s):  
Keir L Birchall ◽  
M G Watson ◽  
J Aird
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Growth Rates ◽  
Dwarf Galaxies ◽  
Optical Emission ◽  
Host Galaxy ◽  
X Ray ◽  
Wide Range ◽  
Accretion Rates ◽  
Parent Sample

ABSTRACT In this work we present a robust quantification of X-ray selected AGN in local (z ≤ 0.25) dwarf galaxies ($M_\mathrm{*} \le 3 \times 10^9 \, \mathrm{M_\odot }$). We define a parent sample of 4331 dwarf galaxies found within the footprint of both the MPA-JHU galaxy catalogue (based on SDSS DR8) and 3XMM DR7, performed a careful review of the data to remove misidentifications and produced a sample of 61 dwarf galaxies that exhibit nuclear X-ray activity indicative of an AGN. We examine the optical emission line ratios of our X-ray selected sample and find that optical AGN diagnostics fail to identify 85 per cent of the sources. We then calculated the growth rates of the black holes powering our AGN in terms of their specific accretion rates (∝ LX/M*, an approximate tracer of the Eddington ratio). Within our observed sample, we found a wide range of specific accretion rates. After correcting the observed sample for the varying sensitivity of 3XMM, we found further evidence for a wide range of X-ray luminosities and specific accretion rates, described by a power law. Using this corrected AGN sample we also define an AGN fraction describing their relative incidence within the parent sample. We found the AGN fraction increases with host galaxy mass (up to ≈6 per cent) for galaxies with X-ray luminosities between $10^{39} \, $ and $10^{42} \, \mathrm{erg\, s^{-1}}$, and by extrapolating the power law to higher luminosities, we found evidence to suggest the fraction of luminous AGN ($L_\mathrm{X} \ge 10^{42.4} \, \mathrm{erg\, s^{-1}}$) is constant out to z ≈ 0.7.

scholarly journals A Link Between Seyfert Emission-Line Widths and X-Ray Continuum Slopes

1997 ◽  
Vol 159 ◽  
pp. 248-251
Author(s):  
Th. Boile ◽  
W.N. Brandt
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Optical Emission ◽  
Emission Lines ◽  
Narrow Line ◽  
Rapid Variability ◽  
X Ray ◽  
Accretion Rates ◽  
Line Widths ◽  
Almost All

AbstractThis paper reports on AGN with extremely soft X-ray spectra observed with ROSAT. From their optical emission lines, these objects are classified as narrow-line Seyfert 1 galaxies (NLSl), almost all with extremely large Fe II/Hβ flux ratios and relatively narrow optical lines of hydrogen. NLSl have generally steeper soft X-ray continuum slopes than normal Seyfert 1s, and there may exist an anticorrelation between 0.1–2.4 keV continuum slope and the FWHM of the Hβ line. Objects with steep 0.1–2.4 keV continuum slopes and Hβ FWHM > 3000 km s−1 are clearly discriminated against by nature. When simple power-law models are fit to the data, photon indices reach values up to about 5, much higher than is usually seen in Seyfert 1s. Models with smaller-mass black holes and/or higher accretion rates show some promise to explain the relation between the FWHM of the Hβ line and the X-ray continuum slope. We further report evidence for persistent giant and rapid variability in the ultrasoft narrow-line Seyfert 1 galaxy IRAS 13224–3809.

An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750

2019 ◽  
Vol 15 (S356) ◽  
pp. 376-376
Author(s):  
Ingyin Zaw
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dwarf Galaxies ◽  
Dwarf Galaxy ◽  
Host Galaxy ◽  
Scaling Relations ◽  
Host Galaxies ◽  
Seed Formation ◽  
Maser Emission ◽  
Water Masers

AbstractNuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.

Single Crystal Wurtzitic Aluminum Nitride Growth on Silicon Using Supersonic Gas Jets

1995 ◽  
Vol 395 ◽  
Author(s):  
S. A. Ustin ◽  
L. Lauhon ◽  
K. A. Brown ◽  
D. Q. Hu ◽  
W. Ho
Keyword(s):  
Aluminum Nitride ◽  
Growth Rates ◽  
High Energy ◽  
X Ray Diffraction ◽  
Rutherford Back Scattering ◽  
X Ray ◽  
Supersonic Molecular Beam ◽  
Supersonic Beams ◽  
Wide Range

ABSTRACTHighly oriented aluminum nitride (0001) films have been grown on Si(001) and Si (111) substrates at temperatures between 550° C and 775° C with dual supersonic molecular beam sources. Triethylaluminum (TEA;[(C2H5)3Al]) and ammonia (NH3) were used as precursors. Hydrogen, helium, and nitrogen were used as seeding gases for the precursors, providing a wide range of possible kinetic energies for the supersonic beams due to the disparate masses of the seed gases. Growth rates of AIN were found to depend strongly on the substrate orientation and the kinetic energy of the incident precursor; a significant increase in growth rate is seen when seeding in hydrogen or helium as opposed to nitrogen. Growth rates were 2–3 times greater on Si(001) than on Si(111). Structural characterization of the films was done by reflection high energy electron diffraction (RHEED) and x-ray diffraction (XRD). X-ray rocking curve (XRC) full-width half-maxima (FWHM) were seen as small as 2.5°. Rutherford back scattering (RBS) was used to determine the thickness of the films and their chemical composition. Films were shown to be nitrogen rich, deviating from perfect stoichiometry by 10%–20%. Surface analysis was performed by Auger electron spectroscopy (AES).

scholarly journals Line-driven disc wind in near-Eddington active galactic nuclei: decrease of mass accretion rate due to powerful outflow

2020 ◽  
Vol 494 (3) ◽  
pp. 3616-3626 ◽  
Author(s):  
Mariko Nomura ◽  
Ken Ohsuga ◽  
Chris Done
Keyword(s):  
Black Holes ◽  
Mass Loss ◽  
Active Galactic Nuclei ◽  
Accretion Rate ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Radiation Hydrodynamics ◽  
Iterative Technique ◽  
X Ray ◽  
Mass Accretion Rate

ABSTRACT Based on recent X-ray observations, ultrafast outflows from supermassive black holes are expected to have enough energy to dramatically affect their host galaxy but their launch and acceleration mechanisms are not well understood. We perform two-dimensional radiation hydrodynamics simulations of UV line-driven disc winds in order to calculate the mass-loss rates and kinetic power in these models. We develop a new iterative technique that reduces the mass accretion rate through the inner disc in response to the wind mass-loss. This makes the inner disc less UV bright, reducing the wind power compared to previous simulations which assumed a constant accretion rate with radius. The line-driven winds in our simulations are still extremely powerful, with around half the supplied mass accretion rate being ejected in the wind for black holes with mass 108–$10^{10}\, \mathrm{ M}_\odot$ accreting at L/LEdd = 0.5–0.9. Our results open up the way for estimating the growth rate of supermassive black hole and evaluating the kinetic energy ejected into the interstellar medium (active galactic nuclei feedback) based on a physical model of line-driven disc winds.

scholarly journals The fates of merging supermassive black holes and a proposal for a new class of X-ray sources

2020 ◽  
Vol 498 (3) ◽  
pp. 3807-3816
Author(s):  
Charles Zivancev ◽  
Jeremiah Ostriker ◽  
Andreas H W Küpper
Keyword(s):  
Black Holes ◽  
Structure Formation ◽  
Hierarchical Structure ◽  
Dynamical Evolution ◽  
Supermassive Black Holes ◽  
Host Galaxy ◽  
X Ray ◽  
Massive Galaxies ◽  
New Class ◽  
Low Mass

ABSTRACT We perform N-body simulations on some of the most massive galaxies extracted from a cosmological simulation of hierarchical structure formation with total masses in the range 1012 M⊙ &lt; Mtot &lt; 3 × 1013 M⊙ from 4 ≥ z ≥ 0. After galactic mergers, we track the dynamical evolution of the infalling black holes (BHs) around their host’s central BHs (CBHs). From 11 different simulations, we find that, of the 86 infalling BHs with masses &gt;104 M⊙, 36 merge with their host’s CBH, 13 are ejected from their host galaxy, and 37 are still orbiting at z = 0. Across all galaxies, 33 BHs are kicked to a higher orbit after close interactions with the CBH binary or multiple, after which only one of them merged with their hosts. These orbiting BHs should be detectable by their anomalous (not low-mass X-ray binary) spectra. The X-ray luminosities of the orbiting massive BHs at z = 0 are in the range $10^{28}-10^{43}\, \mathrm{erg}~\mathrm{s}^{-1}$, with a currently undetectable median value of $10^{33}\, \mathrm{erg}~\mathrm{s}^{-1}$. However, the most luminous ∼5 per cent should be detectable by existing X-ray facilities.

In Situ Synchrotron X-ray Absorption Experiments and Modelling of the Growth Rates of Electrochemically Deposited ZnO Nanostructures

2007 ◽  
Vol 1017 ◽  
Author(s):  
Bridget Ingham ◽  
Benoit N. Illy ◽  
Jade R. Mackay ◽  
Stephen P. White ◽  
Shaun C. Hendy ◽  
...  
Keyword(s):  
Growth Rates ◽  
High Resolution Electron Microscopy ◽  
Ex Situ ◽  
X Ray ◽  
Deposition Parameters ◽  
Wide Range ◽  
Electrochemically Deposited ◽  
Electrochemical Current ◽  
X Ray Absorption

AbstractZnO is known to produce a wide variety of nanostructures that have enormous scope for optoelectronic applications. Using an aqueous electrochemical deposition technique, we are able to tightly control a wide range of deposition parameters (Zn2+ concentration, temperature, potential, time) and hence the resulting deposit morphology. By simultaneously conducting synchrotron x-ray absorption spectroscopy (XAS) experiments during the deposition, we are able to directly monitor the growth rates of the nanostructures, as well as providing direct chemical speciation of the films. In situ experiments such as these are critical to understanding the nucleation and growth of such nanostructures.Recent results from in situ XAS synchrotron experiments demonstrate the growth rates as a function of potential and Zn2+ concentration. These are compared with the electrochemical current density recorded during the deposition, and the final morphology revealed through ex situ high resolution electron microscopy. The results are indicative of two distinct growth regimes, and simultaneous changes in the morphology are observed.These experiments are complemented by modelling the growth of the rods in the transport-limited case, using the Nernst-Planck equations in 2 dimensions, to yield the growth rate of the volume, length, and radius as a function of time.

scholarly journals X-ray time lags from a pivoting power law in black holes

2004 ◽  
Vol 414 (3) ◽  
pp. 795-806 ◽  
Author(s):  
E. Körding ◽  
H. Falcke
Keyword(s):  
Black Holes ◽  
Power Law ◽  
Time Lags ◽  
X Ray

scholarly journals Wide-Angle Quasar Feedback

2015 ◽  
Vol 11 (S319) ◽  
pp. 58-58
Author(s):  
George Chartas ◽  
Sarah Strickland
Keyword(s):  
Black Holes ◽  
Spectral Line ◽  
Absorption Line ◽  
Inclination Angle ◽  
Solid Angle ◽  
Host Galaxy ◽  
Wide Angle ◽  
X Ray ◽  
Spectral Line Profile ◽  
Excess Component

AbstractWe present results from the detection of relativistic winds launched near the innermost stable circular orbits of supermassive black holes. A recent detection of a powerful wind in the X-ray-bright narrow absorption line (NAL) z=1.51 quasar HS 0810+2554 strengthens the case that quasars play a significant role in feedback. In both deep Chandra and XMM-Newton observations of HS 0810 we detected blueshifted absorption lines implying outflowing velocities ranging from 0.1c and 0.4c. The presence of both an emission line at 6.8 keV and an absorption line at 7.8 keV in the spectral line profile of HS 0810 is a characteristic feature of a P-Cygni profile supporting the presence of an expanding outflowing highly ionized Fe absorber. A hard excess component is detected in the XMM-Newton observation of HS 0810 possibly originating from reflection off the disk. Modelling of the XMM-Newton spectrum constrains the inclination angle to be < 35° (68% confidence). The presence of relativistic winds in both low inclination angle NAL quasars as well as in high inclination angle BAL quasars implies that the solid angle of quasar winds may be quite large. The larger solid angle of quasar winds would also indicate that their contribution to the regulation of the host galaxy may be more important than previously thought.

scholarly journals An X-Ray + Radio Search for Massive Black Holes in Blue Compact Dwarf Galaxies

2019 ◽  
Vol 884 (1) ◽  
pp. 78 ◽  
Author(s):  
Colin J. Latimer ◽  
Amy E. Reines ◽  
Richard M. Plotkin ◽  
Thomas D. Russell ◽  
James J. Condon
Keyword(s):  
Black Holes ◽  
Dwarf Galaxies ◽  
Massive Black Holes ◽  
X Ray

scholarly journals Ultrasoft Narrow-line Seyfert 1 Galaxies: An Extreme of Accretion onto Supermassive Black Holes

2000 ◽  
Vol 195 ◽  
pp. 207-208
Author(s):  
W. N. Brandt
Keyword(s):  
Black Holes ◽  
Supermassive Black Holes ◽  
High Mass ◽  
General Context ◽  
Narrow Line ◽  
X Ray ◽  
Basic Properties ◽  
The Future ◽  
Accretion Rates ◽  
New Phenomena

X-ray studies of ultrasoft narrow-line Seyfert 1 galaxies are revealing surprising new phenomena that are expanding our understanding of Seyfert activity, and they may well allow us to observe the effects of high mass accretion rates onto supermassive black holes. I briefly review the basic properties of these galaxies, their importance in a general context, and the prospects for studying them further in the future.

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