Reverberation Mapping of IC 4329A Bentz, Misty C.; Onken, Christopher A.; Street, Rachel ...
The Astrophysical journal,
02/2023, Letnik:
944, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
We present the results of a new reverberation mapping campaign for the broad-line active galactic nucleus (AGN) in the edge-on spiral IC 4329A. Monitoring of the optical continuum with
V-
...band photometry and broad emission-line flux variability with moderate-resolution spectroscopy allowed emission-line light curves to be measured for H
β
, H
γ
, and He
ii
λ
4686. We find a time delay of
16.3
−
2.3
+
2.6
days for H
β
, a similar time delay of
16.0
−
2.6
+
4.8
days for H
γ
, and an unresolved time delay of
−
0.6
−
3.9
+
3.9
days for He
ii
. The time delay for H
β
is consistent with the predicted value from the relationship between AGN luminosity and broad-line region radius, after correction for the ∼2.4 mag of intrinsic extinction at 5100 Å. Combining the measured time delay for H
β
with the broad emission-line width and an adopted value of 〈
f
〉 = 4.8, we find a central supermassive black hole mass of
M
BH
=
6.8
−
1.1
+
1.2
×
10
7
M
⊙
. Velocity-resolved time delays were measured across the broad H
β
emission-line profile and may be consistent with an “M”-like shape. Modeling of the full reverberation response of H
β
was able to provide only modest constraints on some parameters, but does exhibit agreement with the black hole mass and average time delay. The models also suggest that the AGN structure is misaligned by a large amount from the edge-on galaxy disk. This is consistent with expectations from the unified model of AGNs, in which broad emission lines are expected to be visible only for AGNs that are viewed at relatively face-on inclinations.
ABSTRACT We present the results of a reverberation campaign targeting MGC-06-30-15. Spectrophotometric monitoring and broad-band photometric monitoring over the course of four months in spring 2012 ...allowed a determination of a time delay in the broad Hβ emission line of τ = 5.3 1.8 days in the rest frame of the active galactic nucleus (AGN). Combined with the width of the variable portion of the emission line, we determine a black hole mass of MBH = (1.6 0.4) × 106 M . Both the Hβ time delay and the black hole mass are in good agreement with expectations from the RBLR-L and MBH- relationships for other reverberation-mapped AGNs. The Hβ time delay is also in good agreement with the relationship between Hβ and broad-band near-IR delays, in which the effective size of the broad-line region is ∼4-5 times smaller than the inner edge of the dust torus. Additionally, the reverberation-based mass is in good agreement with estimates from the scaling relationship of the break in the X-ray power spectral density, and with constraints based on stellar kinematics derived from integral field spectroscopy of the inner ∼0.5 kpc of the galaxy.
We present spectroscopic and photometric monitoring of NGC 3783 conducted throughout the first half of 2020. Time delays between the continuum variations and the response of the broad optical ...emission lines were clearly detected, and we report reverberation measurements for Hβ, He ii λ4686, Hγ, and Hδ. From the time delay in the broad Hβ emission line and the line width in the variable portion of the spectrum, we derive a black hole mass of M . This is slightly smaller than, but consistent with, previous determinations. However, our significantly improved time sampling (Tmed = 1.7 days compared to Tmed = 4.0 days) has reduced the uncertainties on both the time delay and the derived mass by ∼50%. We also detect clear velocity-resolved time delays across the broad Hβ profile, with shorter lags in the line wings and a longer lag in the line core. Future modeling of the full velocity-resolved time-delay response will further improve the reverberation-based mass for NGC 3783, adding it to the small but growing sample of active galactic nuclei for which we have constrained the black hole mass as well as the geometry and kinematics of the broad-ine region. Upcoming MUSE observations at the Very Large Telescope will also allow NGC 3783 to join the smaller sample of black holes where reverberation masses and masses from stellar dynamical modeling may be directly compared.
Abstract
We describe the results of a new reverberation mapping program focused on the nearby Seyfert galaxy NGC 3227. Photometric and spectroscopic monitoring was carried out from 2022 December to ...2023 June with the Las Cumbres Observatory network of telescopes. We detected time delays in several optical broad emission lines, with H
β
having the longest delay at
τ
cent
=
4.0
−
0.9
+
0.9
days and He
ii
having the shortest delay with
τ
cent
=
0.9
−
0.8
+
1.1
days. We also detect velocity-resolved behavior of the H
β
emission line, with different line-of-sight velocities corresponding to different observed time delays. Combining the integrated H
β
time delay with the width of the variable component of the emission line and a standard scale factor suggests a black hole mass of
M
BH
=
1.1
−
0.3
+
0.2
×
10
7
M
⊙
. Modeling of the full velocity-resolved response of the H
β
emission line with the phenomenological code
CARAMEL
finds a similar mass of
M
BH
=
1.2
−
0.7
+
1.5
×
10
7
M
⊙
and suggests that the H
β
-emitting broad-line region (BLR) may be represented by a biconical or flared disk structure that we are viewing at an inclination angle of
θ
i
≈ 33° and with gas motions that are dominated by rotation. The new photoionization-based BLR modeling tool
BELMAC
finds general agreement with the observations when assuming the best-fit
CARAMEL
results; however,
BELMAC
prefers a thick-disk geometry and kinematics that are equally composed of rotation and inflow. Both codes infer a radially extended and flattened BLR that is not outflowing.
We have recently completed a 64-night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 12 nearby (z < 0.05) ...Seyfert 1 galaxies with expected masses in the range {approx}10{sup 6}-10{sup 7} M{sub sun} and also the well-studied nearby active galactic nucleus (AGN) NGC 5548. Nine of the objects in the sample (including NGC 5548) showed optical variability of sufficient strength during the monitoring campaign to allow for a time lag to be measured between the continuum fluctuations and the response to these fluctuations in the broad H{beta} emission, which we have previously reported. We present here the light curves for the H{alpha}, H{gamma}, He II {lambda}4686, and He I {lambda}5876 emission lines and the time lags for the emission-line responses relative to changes in the continuum flux. Combining each emission-line time lag with the measured width of the line in the variable part of the spectrum, we determine a virial mass of the central supermassive black hole from several independent emission lines. We find that the masses are generally consistent within the uncertainties. The time-lag response as a function of velocity across the Balmer line profiles is examined for six of the AGNs. We find similar responses across all three Balmer lines for Arp 151, which shows a strongly asymmetric profile, and for SBS 1116+583A and NGC 6814, which show a symmetric response about zero velocity. For the other three AGNs, the data quality is somewhat lower and the velocity-resolved time-lag response is less clear. Finally, we compare several trends seen in the data set against the predictions from photoionization calculations as presented by Korista and Goad. We confirm several of their predictions, including an increase in responsivity and a decrease in the mean time lag as the excitation and ionization level for the species increases. Specifically, we find the time lags of the optical recombination lines to have weighted mean ratios of {tau}(H{alpha}):{tau}(H{beta}):{tau}(H{gamma}):{tau}(He I):{tau}(He II) = 1.54:1.00:0.61:0.36:0.25. Further confirmation of photoionization predictions for broad-line gas behavior will require additional monitoring programs for these AGNs while they are in different luminosity states.
Abstract
A complete map of the youngest stellar populations of the Milky Way in the era of all-sky surveys is one of the most challenging goals in modern astrophysics. The characterization of the ...youngest stellar components is crucial not only for a global overview of the Milky Way’s structure, of the Galactic thin disk, and its spiral arms, but also for local studies. In fact, the identification of star-forming regions (SFRs) and the comparison with the environment in which they form are also fundamental to put SFRs in the context of the surrounding giant molecular clouds and to understand still unknown physical mechanisms related to star and planet formation processes. In 10 yr of observations, the Vera C. Rubin Legacy Survey of Space and Time (Rubin LSST) will achieve an exquisite photometric depth that will allow us to significantly extend the volume within which we will be able to discover new SFRs and to enlarge the region of our own Galaxy we have detailed knowledge about. We describe here a metric that estimates the total number of young stars with ages
t
< 10 Myr and masses >0.3
M
⊙
that will be detected with the Rubin LSST observations in the
gri
bands at a 5
σ
magnitude significance. We examine the results of our metric adopting the most recent simulated Rubin LSST survey strategies in order to evaluate the impact that different observing strategies might have on our science case.
Abstract
We report the first unambiguous detection and mass measurement of an isolated stellar-mass black hole (BH). We used the Hubble Space Telescope (HST) to carry out precise astrometry of the ...source star of the long-duration (
t
E
≃ 270 days), high-magnification microlensing event MOA-2011-BLG-191/OGLE-2011-BLG-0462 (hereafter designated as MOA-11-191/OGLE-11-462), in the direction of the Galactic bulge. HST imaging, conducted at eight epochs over an interval of 6 yr, reveals a clear relativistic astrometric deflection of the background star’s apparent position. Ground-based photometry of MOA-11-191/OGLE-11-462 shows a parallactic signature of the effect of Earth’s motion on the microlensing light curve. Combining the HST astrometry with the ground-based light curve and the derived parallax, we obtain a lens mass of 7.1 ± 1.3
M
⊙
and a distance of 1.58 ± 0.18 kpc. We show that the lens emits no detectable light, which, along with having a mass higher than is possible for a white dwarf or neutron star, confirms its BH nature. Our analysis also provides an absolute proper motion for the BH. The proper motion is offset from the mean motion of Galactic disk stars at similar distances by an amount corresponding to a transverse space velocity of ∼45 km s
−1
, suggesting that the BH received a “natal kick” from its supernova explosion. Previous mass determinations for stellar-mass BHs have come from radial velocity measurements of Galactic X-ray binaries and from gravitational radiation emitted by merging BHs in binary systems in external galaxies. Our mass measurement is the first for an isolated stellar-mass BH using any technique.
We report the analysis of OGLE-2019-BLG-0960, which contains the smallest mass-ratio microlensing planet found to date (q = 1.2–1.6 × 10^(−5) at 1σ). Although there is substantial uncertainty in the ...satellite parallax measured by Spitzer, the measurement of the annual parallax effect combined with the finite source effect allows us to determine the mass of the host star (M(L) = 0.3–0.6 Mꙩ), the mass of its planet (m(p) = 1.4–3.1 Mꚛ), the projected separation between the host and planet (a(⊥) = 1.2–2.3 au), and the distance to the lens system (D(L) = 0.6–1.2 kpc). The lens is plausibly the blend, which could be checked with adaptive optics observations. As the smallest planet clearly below the break in the mass-ratio function, it demonstrates that current experiments are powerful enough to robustly measure the slope of the mass-ratio function below that break. We find that the cross-section for detecting small planets is maximized for planets with separations just outside of the boundary for resonant caustics and that sensitivity to such planets can be maximized by intensively monitoring events whenever they are magnified by a factor A > 5. Finally, an empirical investigation demonstrates that most planets showing a degeneracy between (s > 1) and (s < 1) solutions are not in the regime (|log s| ≫ 0) for which the "close"/"wide" degeneracy was derived. This investigation suggests that there is a link between the "close"/"wide" and "inner/outer" degeneracies and also that the symmetry in the lens equation goes much deeper than symmetries uncovered for the limiting cases.
The kinematics of isolated brown dwarfs in the Galaxy, beyond the solar neighborhood, is virtually unknown. Microlensing has the potential to probe this hidden population, as it can measure both the ...mass and five of the six phase-space coordinates (all except the radial velocity) even of a dark isolated lens. However, the measurements of both the microlens-parallax and finite-source effects are needed in order to recover the full information. Here, we combine the Spitzer satellite parallax measurement with the ground-based light curve, which exhibits strong finite-source effects, of event OGLE-2017-BLG-0896. We find two degenerate solutions for the lens (due to the known satellite-parallax degeneracy), which are consistent with each other except for their proper motion. The lens is an isolated brown dwarf with a mass of either 18 1 MJ or 20 1 MJ. This is the lowest isolated-object mass measurement to date, only ∼45% more massive than the theoretical deuterium-fusion boundary at solar metallicity, which is the common definition of a free-floating planet. The brown dwarf is located at either 3.9 0.1 kpc or 4.1 0.1 kpc toward the Galactic bulge, but with proper motion in the opposite direction of disk stars, with one solution suggesting it is moving within the Galactic plane. While it is possibly a halo brown dwarf, it might also represent a different, unknown population.
PDF
