56 research outputs found
Moral Structure Falls Out of General Event Structure
The notion of agency has been explored within research in moral psychology and, quite separately, within research in linguistics. Moral psychologists have suggested that agency attributions play a role in moral judgments, while linguists have argued that agency attributions play a role in syntactic intuitions.
To explore the connection between these two lines of research, we report the results of an experiment in which we manipulate syntactic cues for agency and show a corresponding impact on moral judgments. This result suggests that the two effects observed previously — in morality and in syntax — might each be a reflection of a more general capacity to understand event structure
Overview of RS-25 Adaptation Hot-Fire Test Series for SLS, Status and Lessons Learned
No abstract availabl
The complex radio and X-ray structure in the nuclear regions of the active galaxy NGC1365
We present a multiwavelength analysis of the prominent active galaxy NGC1365,
in particular looking at the radio and X-ray properties of the central regions
of the galaxy.
We analyse ROSAT observations of NGC1365, and discuss recent ASCA results. In
addition to a number of point sources in the vicinity of NGC1365, we find a
region of X-ray emission extending along the central bar of the galaxy,
combined with an emission peak near the centre of the galaxy. This X-ray
emission is centred on the optical/radio nucleus, but is spatially extended.
The X-ray spectrum can be well fitted by a thermal plasma model, with
kT=0.6-0.8keV and a low local absorbing column. The thermal spectrum is
suggestive of starburst emission rather than emission from a central
black-hole.
The ATCA radio observations show a number of hotspots, located in a ring
around a weak radio nucleus. Synchrotron emission from electrons accelerated by
supernovae and supernova remnants (SNRs) is the likely origin of these
hotspots. The radio nucleus has a steep spectrum, indicative perhaps of an AGN
or SNRs. The evidence for a jet emanating from the nucleus is at best marginal.
The extent of the radio ring is comparable to the extended central X-ray
source.Comment: 13 pages, 5 figures, to be published in MNRA
Extragalactic H_2O masers and X-ray absorbing column densities
Having conducted a search for the 22 GHz water vapor line towards galaxies
with nuclear activity, large nuclear column densities or high infrared
luminosities, we present H_2O spectra for NGC2273, UGC5101 and NGC3393 with
isotropic luminosities of 7, 1500, and 400 L_sun. The H_2O maser in UGC5101 is
by far the most luminous yet found in an ultraluminous infrared galaxy. NGC3393
reveals the classic spectrum of a `disk maser', represented by three distinct
groups of Doppler components. As in all other known cases except NGC4258, the
rotation velocity of the putative masing disk is well below 1000 km/s. Based on
the literature and archive data, X-ray absorbing column densities are compiled
for the 64 galaxies with reported maser sources beyond the Magellanic Clouds.
For NGC2782 and NGC5728, we present Chandra archive data that indicate the
presence of an active galactic nucleus in both galaxies. The correlation
between absorbing column and H_2O emission is analyzed. There is a striking
difference between kilo- and megamasers with megamasers being associated with
higher column densities. All kilomasers (L_H_2O < 10 L_sun) except NGC2273 and
NGC5194 are Compton-thin, i.e. their absorbing columns are < 10^24 cm^-2. Among
the H_2O megamasers, 50% arise from Compton-thick and 85% from heavily obscured
(> 10^23 cm^-2) active galactic nuclei. These values are not larger but
consistent with those from samples of Seyfert 2 galaxies not selected on the
basis of maser emission. The similarity in column densities can be explained by
small deviations in position between maser spots and nuclear X-ray source and a
high degree of clumpiness in the circumnuclear interstellar medium.Comment: 16 pages, 7 figures, 5 tables. Accepted for publication in A&
XMM-Newton view of galaxy pairs: activation of quiescent black holes?
We report on XMM-Newton observations of three nearby galaxy pairs,
AM0707-273, AM1211-465, and AM2040-674. All six galaxies were previously
classified as HII galaxies based on optical and IR spectroscopic analysis. All
galaxies were detected with XMM-Newton and each member was isolated and
analyzed independently. The X-ray spectra reveal strong evidence of AGN
activity in the NE member of AM1211-465 pair. We measured a luminosity of
1.94(+0.11/-0.15)x10^42 erg/s in the 2-10 keV band and the presence of a
neutral FeK_alpha line with a confidence level of 98.8%. The high nH value,
2.2+/-0.2x10^22 cm^-2, would explain the misclassification of the source.
Marginal evidence of AGN nature was found in the X-ray spectra of AM1211-465SW
and AM0707-273E. The X-ray emission of the three remaining galaxies can be
explained by starburst activity.Comment: Accepted for publication in A&
The composite starburst/AGN nature of the superwind galaxy NGC 4666
We report the discovery of a Compton-thick AGN and of intense star-formation
activity in the nucleus and disk, respectively, of the nearly edge-on superwind
galaxy NGC 4666. Spatially unresolved emission is detected by BeppoSAX only at
energies <10 keV, whereas spatially resolved emission from the whole disk is
detected by XMM-Newton. A prominent (EW ~ 1-2 keV) emission line at ~6.4 keV is
detected by both instruments. From the XMM-Newton data alone the line is
spectrally localized at E ~ 6.42 +/- 0.03 keV, and seems to be spatially
concentrated in the nuclear region of NGC 4666. This, together with the
presence of a flat (Gamma ~ 1.3) continuum in the nuclear region, suggests the
existence of a strongly absorbed (i.e., Compton-thick) AGN, whose intrinsic
2-10 keV luminosity is estimated to be L_{2-10} > 2 x 10^{41} erg/s. At
energies <1 keV the integrated (BeppoSAX) spectrum is dominated by a ~0.25 keV
thermal gas component distributed throughout the disk (resolved by XMM-Newton).
At energies ~2-10 keV, the integrated spectrum is dominated by a steep (G > 2)
power-law (PL) component. The latter emission is likely due to unresolved
sources with luminosity L ~ 10^{38} - 10^{39} erg/s that are most likely
accreting binaries (with BH masses <8 M_sun). Such binaries, which are known to
dominate the X-ray point-source luminosity in nearby star-forming galaxies,
have Gamma ~ 2 PL spectra in the relevant energy range. A Gamma ~ 1.8 PL
contribution from Compton scattering of (the radio-emitting) relativistic
electrons by the ambient FIR photons may add a truly diffuse component to the
2-10 keV emission.Comment: A&A, in press (10 pages, 14 figures.) Full gzipped psfile obtainable
from http://www.bo.iasf.cnr.it/~malaguti/r_stuff.htm
XMM-Newton unveils the complex iron K alpha region of Mrk 279
We present the results of a ~160 ks-long XMM-Newton observation of the
Seyfert 1 galaxy Mrk 279. The spectrum shows evidence of both broad and narrow
emission features. The Fe K alpha line may be equally well explained by a
single broad Gaussian (FWHM~10,000 km/s) or by two components: an unresolved
core plus a very broad profile (FWHM~14,000 km/s). For the first time we
quantified, via the "locally optimally emitting cloud" model, the contribution
of the broad line region (BLR) to the absolute luminosity of the broad
component of the Fe K alpha at 6.4 keV. We find that the contribution of the
BLR is only ~3%. In the two-line component scenario, we also evaluated the
contribution of the highly ionized gas component, which produces the FeXXVI
line in the iron K region. This contribution to the narrow core of the Fe K
alpha line is marginal <0.1%. Most of the luminosity of the unresolved,
component of Fe K alpha may come from the obscuring torus, while the very-broad
associated component may come from the accretion disk. However, models of
reflection by cold gas are difficult to test because of the limited energy
band. The FeXXVI line at 6.9 keV is consistent to be produced in a high column
density (N_H~10^23 cm^{-2}), extremely ionized (log\xi~5.5-7) gas. This gas may
be a highly ionized outer layer of the torus.Comment: 10 pages, 9 figures, accepted for publication in Astronomy and
Astrophysic
On the nature of unabsorbed Seyfert 2 galaxies
We present an analysis of six 12 um selected Seyfert 2 galaxies that have
been reported to be unabsorbed in the X-ray. By comparing the luminosities of
these galaxies in the mid-IR (12um), optical ([O III]) and hard X-ray (2-10
keV), we show that they are all under-luminous in the 2-10 keV X-ray band. Four
of the objects exhibit X-ray spectra indicative of a hard excess, consistent
with a heavily obscured X-ray component and hence a hidden nucleus. In these
objects the softer X-rays may be dominated by a strong soft scattered continuum
or contamination from the host galaxy, which is responsible for the unabsorbed
X-ray spectra observed, and accounts for the anomalously low 2-10 keV X-ray
luminosity. We confirm this assertion in NGC4501 with a Chandra observation,
which shows hard X-ray emission coincident with the nucleus, consistent with
heavy absorption, and a number of contaminating softer sources which account
for the bulk of the softer emission. We point out that such 'Compton thick'
sources need not necessarily present iron Ka emission of high EW. An example in
our sample is IRASF01475-0740, which we know must host an obscured AGN as it
hosts a HBLR seen in scattered light (Tran 2003). The X-ray spectrum is
nonetheless relatively unobscured and the iron Ka line only moderate in
strength. These observations can be reconciled if the hidden nuclear emission
is dominated by transmitted, rather than reflected X-rays, which can then be
weak compared to the soft scattered light or galactic emission. Despite these
considerations, we conclude that NGC3147 & 3660 may intrinsically lack a BLR,
confirming the recent results of Bianchi et al. (2008) for NGC3147. Neither
X-ray spectrum shows signs of hidden hard emission and both sources exhibit
X-ray variability leading us to believe we are viewing the nucleus directly.Comment: 10 pages, 5 figures, accepted for publication at MNRA
BeppoSAX observations of LINER-2 galaxies
We present BeppoSAX observations of 6 ``type-2'' LINER and ``transition''
galaxies (NGC3379, NGC3627, NGC4125, NGC4374, NGC5195 and NGC5879)from the
Ho et al. (1997) spectroscopic sample of nearby galaxies. All objects are
detected in the 2-10 keV band, having luminosities in the range L(2-10 keV)
~ 1x10^{39}- 1x10^{40} erg s-1. The PDS upper limits above 10 keV place
constraints on the presence of a heavily obscured AGN in the case of NGC3379
and NGC4125. No significant variability is detected in any of the objects.
The spectra are described in most cases by a simple power-law model with a
spectral slope of 1.7-2.5 while there is evidence neither for a significant
absorption above the Galactic nor for an FeK emission line. Therefore, based on
the spectral properties alone, it is difficult to differentiate between a
low-luminosity AGN or a star-forming galaxy scenario.
However, imaging observations of NGC3627 and NGC5195 with
Chandra ACIS-S reveal very weak nuclear sources while most of the X-ray flux
originates either in off-nuclear point sources or in diffuse emission. The
above clearly argue in favour of a star-forming origin for the bulk of the
X-ray emission, at least in the above two sources.Comment: 10 pages, to appear in A&
The X-ray emission of local luminous infrared galaxies
We study the X-ray emission of a representative sample of 27 local luminous
infrared galaxies (LIRGs). The median IR luminosity of our sample is log
L_IR/L_sun = 11.2, thus the low-luminosity end of the LIRG class is well
represented. We used new XMM-Newton data as well as Chandra and XMM-Newton
archive data. The soft X-ray (0.5-2 keV) emission of most of the galaxies
(>80%), including LIRGs hosting a Seyfert 2 nucleus, is dominated by
star-formation related processes. These LIRGs follow the star-formation rate
(SFR) versus soft X-ray luminosity correlation observed in local starbursts. We
find that ~15% of the non-Seyfert LIRGs (3 out of 20) have an excess hard X-ray
emission relative to that expected from star-formation that might indicate the
presence of an obscured AGN. The rest of the non-Seyfert LIRGs follow the SFR
versus hard X-ray (2-10 keV) luminosity correlation of local starbursts. The
non-detection of the 6.4 keV Fe K alpha emission line in the non-Seyfert LIRGs
allows us to put an upper limit to the bolometric luminosity of an obscured
AGN, L_bol <1043 erg s-1 . That is, in these galaxies, if they hosted a low
luminosity AGN, its contribution to total luminosity would be less than 10%.
Finally we estimate that the AGN contribution to the total luminosity for our
sample of local LIRGs is between 7% and 10%.Comment: Accepted for Publication in A&A, 22 pages, 9 figure
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