49 research outputs found
Narrow Line Seyfert 1s in the IBISCO sample
We present the broad-band soft and hard X-ray spectral analysis of 8 Narrow
Line Seyfert 1 galaxies extracted from the IBISCO Sample. The study also
focuses on the properties of the NLS1 in our sample in relation to those of the
IBISCO parent Seyfert population. The IBISCO sample comprises 57 AGN selected
from the INTEGRAL IBIS AGN catalogue (in the 20-100 keV band), with z0.05
and covering a wide range of luminosities, BH masses and absorption. All AGN
have also measurements of the molecular gas (H) content of their host
galaxies, through the detection of CO emission lines. The main goals of this
analysis are to accurately determine the X-ray continuum emission, investigate
the presence of absorption features around 7 keV (indicative of the presence of
outflows) and measure the bolometric luminosity in order to study the accretion
parameters of the eight IBISCO NLS1, and study the accretion mechanisms and
investigate the feeding and feedback cycle in these peculiar AGN. Preliminary
results show that NLS1 tend to have higher Eddington ratios and larger
molecular gas fractions than their parent Seyfert population in the IBISCO
sample. Nuclear (AGN) vs. host galaxy properties scaling relations of NLS1 in
relation to the parent Seyfert population are also explored.Comment: 4 pages, 2 figures, 1 table. Proceedings of the conference
"Revisiting narrow-line Seyfert 1 galaxies and their place in the Universe ",
Padova 9-13 April 201
Radio recombination lines from obscured quasars with the SKA
We explore the possibility of detecting hydrogen radio recombination lines
from 0 < z < 10 quasars. We compute the expected Hnalpha flux densities as a
function of absolute magnitude and redshift by considering (i) the range of
observed AGN spectral indices from UV to X-ray bands, (ii) secondary
ionizations from X-ray photons, and (iii) stimulated emission due to nonthermal
radiation. All these effects are important to determine the line fluxes. We
find that the combination of slopes: alpha_X,hard = -1.11, alpha_X,soft = -0.7,
alpha_EUV = -1.3, alpha_UV = -1.7, maximizes the expected flux, f_Hnalpha = 10
microJy for z = 7 quasars with M_AB = -27 in the n = 50 lines; allowed SED
variations produce variations by a factor of 3 around this value. Secondaries
boost the line intensity by a factor of 2 to 4, while stimulated emission in
high-z quasars with M_AB = -26 provides an extra boost to RRL flux observed at
nu = 1 GHz if recombinations arise in HII regions with T_e = 10^3-5 K, n_e =
10^3-5 cm^-3. We compute the sensitivity required for a 5sigma detection of
Hnalpha lines using the SKA, finding that the SKA-MID could detect sources with
M_AB < -27 (M_AB < -26) at z < 8 (z < 3) in less than 100 hrs of observing
time. These observations could open new paths to searches for obscured SMBH
progenitors, complementing X-ray, optical/IR and sub-mm surveys.Comment: 11 pages, 9 figures; to be published in Monthly Notices of the Royal
Astronomical Society Main Journa
Black hole-galaxy co-evolution and the role of feedback
Active galactic nuclei (AGN) are accreting supermassive black holes
co-evolving with their host galaxies through a complex interplay of feeding and
feedback. In this chapter, we first discuss AGN fuelling in galaxies, both in
interacting and isolated systems, focusing on the role that instabilities have
on the angular momentum budget of the gas. We then review observations and
models of feedback through AGN-driven winds from nuclear, sub-pc scales out to
galactic and circumgalactic medium scales. We continue with an overview of
surveys and statistical properties of the AGN population, before concluding
with a discussion on the prospects for the future facilities, focusing in
particular on Athena.Comment: Invited Chapter of Section "Active Galactic Nuclei in X- and
Gamma-rays" (Section Editors: A. De Rosa and C. Vignali) of the "Handbook of
X-ray and Gamma-ray Astrophysics" (Editors: C. Bambi and A. Santangelo),
Springer Natur
X-ray spectroscopy of the z=6.4 quasar J1148+5251
We present the 78-ks Chandra observations of the quasar SDSS
J1148+5251. The source is clearly detected in the energy range 0.3-7 keV with
42 counts (with a significance ). The X-ray spectrum is
best-fitted by a power-law with photon index absorbed by a gas
column density of .
We measure an intrinsic luminosity at 2-10 keV and 10-40 keV equal to , comparable with luminous local and
intermediate-redshift quasar properties. Moreover, the X-ray to optical
power-law slope value () of J1148 is consistent
with the one found in quasars with similar rest-frame 2500 \AA ~luminosity
(\AA). Then we use Chandra data
to test a physically motivated model that computes the intrinsic X-ray flux
emitted by a quasar starting from the properties of the powering black hole and
assuming that X-ray emission is attenuated by intervening, metal-rich () molecular clouds distributed on kpc scales in the host
galaxy. Our analysis favors a black hole mass and a molecular hydrogen mass , in good agreement with estimates obtained from previous studies. We
finally discuss strengths and limits of our analysis.Comment: 9 pages, 3 figures, 1 table, MNRAS in pres
Dynamical signature of a stellar bulge in a quasar host galaxy at
We present a dynamical analysis of a quasar-host galaxy at (SDSS
J2310+1855) using a high-resolution ALMA observation of the [CII] emission
line. The observed rotation curve was fitted with mass models that considered
the gravitational contribution of a thick gas disc, a thick star-forming
stellar disc, and a central mass concentration, which is likely due to a
combination of a spheroidal component (i.e. a stellar bulge) and a supermassive
black hole (SMBH). The SMBH mass of , previously
measured using the CIV and MgII emission lines, is not sufficient to explain
the high velocities in the central regions. Our dynamical model suggests the
presence of a stellar bulge with a mass of in this object, when the Universe was younger than 1 Gyr. To finally
be located on the local relation, the bulge mass
should increase by a factor of 40 from to 0, while the SMBH mass
should grow by a factor of 4 at most. This points towards asynchronous
galaxy-BH co-evolution. Imaging with the JWST will allow us to validate this
scenario.Comment: 8 pages, 4 figures, 3 tables. Accepted by A&
The Rise of Active Galactic Nuclei in the GAlaxy Evolution and Assembly semi-analytic model
We present a new implementation of the GAlaxy Evolution and Assembly (GAEA)
semi-analytic model, that features an improved modelling of the process of cold
gas accretion onto supermassive black hole (SMBHs), derived from both analytic
arguments and high-resolution simulations. We consider different scenarios for
the loss of angular momentum required for the available cold gas to be accreted
onto the central SMBHs, and we compare different combinations of triggering
mechanisms, including galaxy mergers and disc instabilities in star forming
discs. We compare our predictions with the luminosity function (LF) observed
for Active Galactic Nuclei (AGN) and we confirm that a non-instantaneous
accretion timescale (either in the form of a low-angular momentum reservoir or
as an assumed light curve evolution) is needed in order to reproduce the
measured evolution of the AGN-LF and the so-called AGN-downsizing trend.
Moreover, we also study the impact of AGN feedback, in the form of AGN-driven
outflows, on the SF properties of model galaxies, using prescriptions derived
both from empirical studies or from numerical experiments. We show that
AGN-driven outflows are effective in suppressing the residual star formation
rate in massive galaxies () without changing their overall
assembly history. These winds also affect the SFR of lower mass galaxies,
resulting in a too large fraction of passive galaxies at .
Finally, we study the Eddington ratio distribution as a function of SMBH mass,
showing that only objects more massive than are already in a
self-regulated state as inferred from observations.Comment: 19 pages, 12 figures, 1 table, replaced with MNRAS accepted versio
The lively accretion disc in NGC 2992. III. Tentative evidence of rapid Ultra Fast Outflow variability
We report on the 2019 XMM-Newton+NuSTAR monitoring campaign of the Seyfert
galaxy NGC 2992, observed at one of its highest flux levels in the X-rays. The
time-averaged spectra of the two XMM-Newton orbits show Ultra Fast Outflows
(UFOs) absorbing structures above 9 keV with significance. A
detailed investigation of the temporal evolution on a 5 ks time scale
reveals UFO absorption lines at a confidence level 95% (2) in 8 out
of 50 XMM-Newton segments, estimated via Monte Carlo simulations. We observe a
wind variability corresponding to a length scale of 5 Schwarzschild radii
. Adopting the novel Wind in the Ionised Nuclear Environment (WINE) model,
we estimate the outflowing gas velocity (), column density
() and ionisation state ($\log(\xi_0/erg\ cm\
s^{-1})=3.7-4.7\dot{M}_{out}\simeq0.3-0.8 M_{\odot} yr^{-1}\dot{p}_{out}\simeq 20-90 L_{Bol}/c\dot{E}_K \simeq 2-25 L_{Bol}\approx\approx\approx 5 r_S, 10^{11} {cm}^{-3}$, respectively.Comment: Accepted for publication in the Astrophysical Journal. 21 pages, 11
figure
The IBISCO survey: I. Multiphase discs and winds in the Seyfert galaxy Markarian 509
We present the analysis of the ALMA CO(2 1) emission line and the underlying 1.2mm continuum of Mrk 509 with spatial resolution of similar to 270 pc. This local Seyfert 1.5 galaxy, optically classified as a spheroid, is known to host an ionised disc, a starburst ring, and ionised gas winds on both nuclear (ultra-fast outflows) and galactic scales. From CO(2 1) we estimate a molecular gas reservoir of M-H2 = 1.7 x10(9) M-circle dot, located within a disc of size similar to 5.2 kpc, with M-dyn = (2.0 +/- 1.1) x 10(10) M-circle dot inclined at 44 +/- 10 deg. The molecular gas fraction within the disc is mu(gas) = 5%, consistent with that of local star-forming galaxies with similar stellar mass. The gas kinematics in the nuclear region within r similar to 700 pc, that is only marginally resolved at the current angular resolution, suggests the presence of a warped nuclear disc. Both the presence of a molecular disc with ongoing star formation in a starburst ring, and the signatures of a minor merger, are in agreement with the scenario where galaxy mergers produce gas destabilisation, feeding both star formation and AGN activity. The spatially resolved Toomre Q-parameter across the molecular disc is in the range Q(gas) = 0.5-10, and shows that the disc is marginally unstable across the starburst ring, and stable against fragmentation at nucleus and in a lopsided ring-like structure located inside of the starburst ring. We find complex molecular gas kinematics and significant kinematics perturbations at two locations, one within 300 pc of the nucleus and one 1.4 kpc away close to the region with high Q(gas), that we interpret as molecular winds with velocity v(98) = 200-250 km s(-1). The total molecular outflow rate is in the range 6.4-17.0 M-circle dot yr(-1) for the optically thin and thick cases, respectively. The molecular wind total kinetic energy is consistent with a multiphase momentum-conserving wind driven by the AGN with P-of/P-rad in the range 0.06-0.5. The spatial overlap of the inner molecular wind with the ionised wind, and their similar velocity suggest a cooling sequence within a multiphase wind driven by the AGN. The second outer molecular wind component overlaps with the starburst ring, and its energy is consistent with a supernova-driven wind arising from the starburst ring
Star formation efficiency and AGN feedback in narrow-line Seyfert 1 galaxies with fast X-ray nuclear winds
We present the first systematic study of the molecular gas and star formation
efficiency in a sample of ten narrow-line Seyfert 1 galaxies selected to have
X-ray Ultra Fast Outflows and, therefore, to potentially show AGN feedback
effects. CO observations were obtained with the IRAM 30m telescope in six
galaxies and from the literature for four galaxies. We derived the stellar
mass, star formation rate, AGN and FIR dust luminosities by fitting the
multi-band spectral energy distributions with the CIGALE code. Most of the
galaxies in our sample lie above the main sequence (MS) and the molecular
depletion time is one to two orders of magnitude shorter than the one typically
measured in local star-forming galaxies. Moreover, we found a promising
correlation between the star formation efficiency and the Eddington ratio, as
well as a tentative correlation with the AGN luminosity. The role played by the
AGN activity in the regulation of star formation within the host galaxies of
our sample remains uncertain (little or no effect? positive feedback?).
Nevertheless, we can conclude that quenching by the AGN activity is minor and
that star formation will likely stop in a short time due to gas exhaustion by
the current starburst episode.Comment: Published in MNRAS, Volume 524, Issue 2, Pages 3130-314
The fraction and kinematics of broad absorption line quasars across cosmic time
Luminous quasars are powerful targets to investigate the role of feedback
from supermassive black-holes (BHs) in regulating the growth phases of BHs
themselves and of their host galaxies, up to the highest redshifts. Here we
investigate the cosmic evolution of the occurrence and kinematics of BH-driven
outflows, as traced by broad absorption line (BAL) features, due to the C IV
ionic transition. We exploit a sample of 1935 quasars quasars at
with bolometric luminosity log(erg s, drawn
from the Sloan Digital Sky Survey and from the X-shooter legacy survey of
Quasars at Reionisation (XQR-30). We consider rest-frame optical bright quasars
to minimise observational biases due to quasar selection criteria. We apply a
homogeneous BAL identification analysis, based on employing composite template
spectra to estimate the quasar intrinsic emission. We find a BAL quasar
fraction close to 20\% at , while it increases to almost 50\% at
. The velocity and width of the BAL features also increase at
. We exclude that the redshift evolution of the BAL properties is
due to differences in terms of quasar luminosity and accretion rate. These
results suggest significant BH feedback occurring in the 1 Gyr old Universe,
likely affecting the growth of BHs and, possibly, of their host galaxies, as
supported by models of early BH and galaxy evolution.Comment: Accepted for publication in Ap