Axions/axion-like particles (ALPs) are a well-motivated extension of the Standard Model and are generic within String Theory. The X-ray transparency of the intracluster medium (ICM) in galaxy ...clusters is a powerful probe of light ALPs (with mass ); as X-ray photons from an embedded or background source propagate through the magnetized ICM, they may undergo energy-dependent quantum mechanical conversion into ALPs (and vice versa), imprinting distortions on the X-ray spectrum. We present Chandra data for the active galactic nucleus NGC 1275 at the center of the Perseus cluster. Employing a 490 ks High Energy Transmission Gratings exposure, we obtain a high-quality 1-9 keV spectrum free from photon pileup and ICM contamination. Apart from iron-band features, the spectrum is described by a power-law continuum, with any spectral distortions at the <3% level. We compute photon survival probabilities as a function of ALP mass ma and ALP-photon coupling constant for an ensemble of ICM magnetic field models, and then use the NGC 1275 spectrum to constrain the -plane. Marginalizing over magnetic field realizations, the 99.7% credible region limits the ALP-photon coupling to (depending upon magnetic field model) for masses . These are the most stringent limit to date on for these light ALPs, and have already reached the sensitivity limits of next-generation helioscopes and light-shining-through-wall experiments. We highlight the potential of these studies with the next-generation X-ray observatories Athena and Lynx, but note the critical importance of advances in relative calibration of these future X-ray spectrometers.
We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically ...driven blind search for Fe xxv Heα and/or Fe xxvi Lyα absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E 6.7 keV in 20/51 sources at the P
MC ≥ 95 per cent level, which corresponds to ∼40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe xxv Heα and Fe xxvi Lyα at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N
H/cm−2) 23 and log (ξ/erg cm s−1) 4.5, respectively. Measured outflow velocities span a continuous range from <1500 km s−1 up to ∼100 000 km s−1, with mean and median values of ∼0.1 c and ∼0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.
Abstract
We analyze three prototypical black hole X-ray binaries, 4U 1630–472, GRO J1655–40, and H1743–322, in an effort to systematically understand the intrinsic state transition of the observed ...accretion disk winds between
wind-on
and
wind-off
states by utilizing state-of-the-art Chandra/HETGS archival data from multi-epoch observations. We apply our magnetically driven wind models in the context of magnetohydrodynamic (MHD) calculations to constrain (1) their global density slope (
p
), (2) their density (
n
17
) at the foot point of the innermost launching radius, and (3) the abundances of heavier elements (
A
Fe,S,Si
). Incorporating the MHD winds into
xstar
photoionization calculations in a self-consistent manner, we create a library of synthetic absorption spectra given the observed X-ray continua. Our analysis clearly indicates a characteristic bimodal transition of multi-ion X-ray winds; i.e., the wind density gradient is found to steepen (from
p
∼ 1.2–1.4 to ∼1.4–1.5) while its density normalization declines as the source transitions from the
wind-on
to the
wind-off
state. The model implies that the ionized wind remains physically present even in the
wind-off
state, despite its apparent absence in the observed spectra. Supersolar abundances for heavier elements are also favored. Our global multi-ion wind models, taking into account soft X-ray ions as well as Fe K absorbers, show that the internal wind condition plays an important role in wind transitions besides photoionization changes. Simulated XRISM/Resolve and Athena/X-IFU spectra are presented to demonstrate a high fidelity of the multi-ion wind model for a better understanding of these powerful ionized winds in the coming decades.
We present new XMM-Newton and NuSTAR observations of the galaxy merger IRAS F05189-2524, which is classified as an ultraluminous infrared galaxy and optical Seyfert 2 at z = 0.0426. We test a variety ...of spectral models that yield a best fit consisting of an absorbed power law with emission and absorption features in the Fe K band. Remarkably, we find evidence for a blueshifted Fe K absorption feature at E = 7.8 keV (rest frame) which implies an ultrafast outflow (UFO) with vout = 0.11 0.01c. We calculate that the UFO in IRAS F05189-2524 has a mass outflow rate of yr−1, a kinetic power of 8% LAGN, and a momentum rate (or force) of . Comparing the energetics of the UFO to the observed multi-phase outflows at kiloparsec scales yields an efficiency factor of f ∼ 0.05 for an energy-driven outflow. Given the uncertainties, however, we cannot exclude the possibility of a momentum-driven outflow. Comparing IRAS F05189-2524 with nine other objects with observed UFOs and large-scale galactic outflows suggests that there is a range of efficiency factors for the coupling of the energetics of the nuclear and galaxy-scale outflows that likely depend on specific physical conditions in each object.
Abstract X-ray obscuration of active galactic nuclei (AGNs) is considered in the context of ionized winds of stratified structure launched from accretion disks. We argue that a Compton-thick layer of ...a large-scale disk wind can obscure continuum X-rays and also lead to broad UV absorption, such as in the blue wing of C iv ; the former originates from the inner wind and the latter from the outer wind, as a dual role. Motivated by a number of lines of observational evidence showing strong AGN obscuration phenomena in Seyfert 1 AGNs such as NGC 5548, we demonstrate in this work, by utilizing a physically motivated wind model coupled to post-process radiative transfer calculations, that an extended disk wind under certain physical conditions (e.g., morphology and density) could naturally cause a sufficient obscuration qualitatively consistent with UV/X-ray observations. Predicted UV/X-ray correlation is also presented as a consequence of variable spatial size of the wind in this scenario.
ABSTRACT We present a Hubble Space Telescope Space Telescope Imaging Spectrograph spectrum of ASASSN-14li, the first rest-frame ultraviolet (UV) spectrum of a tidal disruption flare (TDF). The ...underlying continuum is well fit by a blackbody with K, an order of magnitude smaller than the temperature inferred from X-ray spectra (and significantly more precise than previous efforts based on optical and near-UV photometry). Superimposed on this blue continuum, we detect three classes of features: narrow absorption from the Milky Way (probably a high-velocity cloud), and narrow absorption and broad (∼2000-8000 km s−1) emission lines at or near the systemic host velocity. The absorption lines are blueshifted with respect to the emission lines by Δv = −(250-400) km s−1. Due both to this velocity offset and the lack of common low-ionization features (Mg ii, Fe ii), we argue these arise from the same absorbing material responsible for the low-velocity outflow discovered at X-ray wavelengths. The broad nuclear emission lines display a remarkable abundance pattern: N iii, N iv, and He ii are quite prominent, while the common quasar emission lines of C iii and Mg ii are weak or entirely absent. Detailed modeling of this spectrum will help elucidate fundamental questions regarding the nature of the emission processes at work in TDFs, while future UV spectroscopy of ASASSN-14li would help to confirm (or refute) the previously proposed connection between TDFs and "N-rich" quasars.
Abstract
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 ultrafast outflows (UFOs) absorbing structures above 9 keV with >3
σ
significance. A detailed investigation of the temporal evolution on a ∼5 ks timescale reveals UFO absorption lines at a confidence level >95% (2
σ
) 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
r
S
. Adopting the novel Wind in the Ionized Nuclear Environment model, we estimate the outflowing gas velocity (
v
= 0.21–0.45
c
), column density (
N
H
= 4–8 × 10
24
cm
−2
) and ionization state (
log
(
ξ
0
/
erg
cm
s
−
1
)
=
3.7
–
4.7
), taking into account geometrical and special relativity corrections. These parameters lead to instantaneous mass outflow rates of
M
̇
out
≃
0.3
–
0.8
M
⊙
yr
−1
, with associated outflow momentum rates
p
̇
out
≃
20
–
90
L
Bol
/
c
and kinetic energy rates
E
̇
K
≃
2
–
25
L
Bol
. We estimate a wind duty cycle of ≈12% and a total mechanical power of ≈2 times the active galactic nuclei (AGN) bolometric luminosity, suggesting that the wind may drive significant feedback effects between the AGN and the host galaxy. Notably, we also provide an estimate for the wind launching radius and density of ≈5
r
S
, 10
11
cm
−3
, respectively.
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