The Type Ia supernova (SN Ia) 2016coj in NGC 4125 (redshift z = 0.00452 0.00006) was discovered by the Lick Observatory Supernova Search 4.9 days after the fitted first-light time (FFLT; 11.1 days ...before B-band maximum). Our first detection (prediscovery) is merely 0.6 0.5 days after the FFLT, making SN 2016coj one of the earliest known detections of an SN Ia. A spectrum was taken only 3.7 hr after discovery (5.0 days after the FFLT) and classified as a normal SN Ia. We performed high-quality photometry, low- and high-resolution spectroscopy, and spectropolarimetry, finding that SN 2016coj is a spectroscopically normal SN Ia, but the velocity of Si ii λ6355 around peak brightness (∼12,600 ) is a bit higher than that of typical normal SNe. The Si ii λ6355 velocity evolution can be well fit by a broken-power-law function for up to a month after the FFLT. SN 2016coj has a normal peak luminosity ( mag), and it reaches a B-band maximum ∼16.0 days after the FFLT. We estimate there to be low host-galaxy extinction based on the absence of Na i D absorption lines in our low- and high-resolution spectra. The spectropolarimetric data exhibit weak polarization in the continuum, but the Si ii line polarization is quite strong (∼0.9% 0.1%) at peak brightness.
The mass of the central black hole in the giant elliptical galaxy M84 has previously been measured by two groups using the same observations of emission-line gas with the Space Telescope Imaging ...Spectrograph (STIS) on the Hubble Space Telescope, giving strongly discrepant results: Bower et al. found M{sub BH} = (1.5{sup +1.1}{sub -0.6}) x 10{sup 9} M{sub sun}, while Maciejewski and Binney estimated M{sub BH} = 4 x 10{sup 8} M{sub sun}. In order to resolve this discrepancy, we have performed new measurements of the gas kinematics in M84 from the same archival data and carried out comprehensive gas-dynamical modeling for the emission-line disk within {approx}70 pc from the nucleus. In comparison with the two previous studies of M84, our analysis includes a more complete treatment of the propagation of emission-line profiles through the telescope and STIS optics, as well as inclusion of the effects of an intrinsic velocity dispersion in the emission-line disk. We find that an intrinsic velocity dispersion is needed in order to match the observed line widths, and we calculate gas-dynamical models both with and without a correction for asymmetric drift. Including the effect of asymmetric drift improves the model fit to the observed velocity field. Our best-fitting model with asymmetric drift gives M{sub BH} = (8.5{sup +0.9}{sub -0.8}) x 10{sup 8} M{sub sun} (68% confidence). This is a factor of {approx}2 smaller than the mass often adopted in studies of the M{sub BH}-{sigma}{sub *} and M{sub BH}-L relationships. Our result provides a firmer basis for the inclusion of M84 in the correlations between black hole mass and host galaxy properties.
Abstract
We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 observations of CO(2–1) emission from the circumnuclear disks in two early-type galaxies, NGC 1380 and NGC 6861. The ...disk in each galaxy is highly inclined (
i
∼ 75°), and the projected velocities of the molecular gas near the galaxy centers are ∼300 km s
−1
in NGC 1380 and ∼500 km s
−1
in NGC 6861. We fit thin disk dynamical models to the ALMA data cubes to constrain the masses of the central black holes (BHs). We created host galaxy models using Hubble Space Telescope images for the extended stellar mass distributions and incorporated a range of plausible central dust extinction values. For NGC 1380, our best-fit model yields
M
BH
= 1.47 × 10
8
M
⊙
with a ∼40% uncertainty. For NGC 6861, the lack of dynamical tracers within the BH’s sphere of influence due to a central hole in the gas distribution precludes a precise measurement of
M
BH
. However, our model fits require a value for
M
BH
in the range of (1–3) × 10
9
M
⊙
in NGC 6861 to reproduce the observations. The BH masses are generally consistent with predictions from local BH–host galaxy scaling relations. Systematic uncertainties associated with dust extinction of the host galaxy light and choice of host galaxy mass model dominate the error budget of both measurements. Despite these limitations, the measurements demonstrate ALMA’s ability to provide constraints on BH masses in cases where the BH’s projected radius of influence is marginally resolved or the gas distribution has a central hole.
We present a dynamical analysis to infer the structural parameters and properties of the two nearby, compact, high-velocity dispersion galaxies MRK 1216 and NGC 1277. Combining deep Hubble Space ...Telescope imaging, wide-field integral field unit stellar kinematics, and complementary long-slit spectroscopic data out to three effective radii, we construct orbit-based models to constrain their black hole masses, dark matter content and stellar mass-to-light ratios. We obtain a black hole mass of log(M
•/M⊙) = 10.1
$_{-0.2}^{+0.1}$
for NGC 1277 and an upper limit of log(M
•/M⊙) = 10.0 for MRK 1216, within 99.7 per cent (3σ) confidence. The stellar mass-to-light ratios span a range of ϒ
V
=
$6.5_{-1.5}^{+1.5}$
in NGC 1277 and ϒ
H
=
$1.8_{-0.8}^{+0.5}$
in MRK 1216 and are in good agreement with single stellar population models of a single power-law Salpeter initial mass function. Even though our models do not place strong constraints on the dark halo parameters, they suggest that dark matter is a necessary ingredient in MRK 1216, with a dark matter contribution of
$22^{+30}_{-20}$
per cent to the total mass budget within one effective radius. NGC 1277, on the other hand, can be reproduced without the need for a dark halo, and a maximal dark matter fraction of 13 per cent within the same radial extent. In addition, we investigate the orbital structures of both galaxies, which are rotationally supported and consistent with photometric multi-Sérsic decompositions, indicating that these compact objects do not host classical, non-rotating bulges formed during recent (z ≤ 2) dissipative events or through violent relaxation. Finally, both MRK 1216 and NGC 1277 are anisotropic, with a global anisotropy parameter δ of 0.33 and 0.58, respectively. While MRK 1216 follows the trend of fast-rotating, oblate galaxies with a flattened velocity dispersion tensor in the meridional plane of the order of β
z
∼ δ, NGC 1277 is highly tangentially anisotropic and seems to belong kinematically to a distinct class of objects.
Abstract
We have modeled the velocity-resolved reverberation response of the H
β
broad emission line in nine Seyfert 1 galaxies from the Lick Active Galactic Nucleus (AGN) Monitoring Project 2016 ...sample, drawing inferences on the geometry and structure of the low-ionization broad-line region (BLR) and the mass of the central supermassive black hole. Overall, we find that the H
β
BLR is generally a thick disk viewed at low to moderate inclination angles. We combine our sample with prior studies and investigate line-profile shape dependence, such as
log
10
(
FWHM
/
σ
)
, on BLR structure and kinematics and search for any BLR luminosity-dependent trends. We find marginal evidence for an anticorrelation between the profile shape of the broad H
β
emission line and the Eddington ratio, when using the rms spectrum. However, we do not find any luminosity-dependent trends, and conclude that AGNs have diverse BLR structure and kinematics, consistent with the hypothesis of transient AGN/BLR conditions rather than systematic trends.
ABSTRACT Located in the Perseus cluster, NGC 1271 is an early-type galaxy with a small effective radius of 2.2 kpc and a large bulge stellar velocity dispersion of 276 km s−1 for its K-band ...luminosity of . We present a mass measurement for the black hole in this compact, high-dispersion galaxy using observations from the Near-infrared Integral Field Spectrometer on the Gemini North telescope assisted by laser guide star adaptive optics, large-scale integral field unit observations with PPAK at the Calar Alto Observatory, and Hubble Space Telescope WFC3 imaging observations. We are able to map out the stellar kinematics both on small spatial scales, within the black hole sphere of influence, and on large scales that extend out to four times the galaxy's effective radius. We find that the galaxy is rapidly rotating and exhibits a sharp rise in the velocity dispersion. Through the use of orbit-based stellar dynamical models, we determine that the black hole has a mass of and the H-band stellar mass-to-light ratio is ( uncertainties). NGC 1271 occupies the sparsely populated upper end of the black hole mass distribution but is very different from the brightest cluster galaxies (BCGs) and giant elliptical galaxies that are expected to host the most massive black holes. Interestingly, the black hole mass is an order of magnitude larger than expectations based on the galaxy's bulge luminosity but is consistent with the mass predicted using the galaxy's bulge stellar velocity dispersion. More compact, high-dispersion galaxies need to be studied using high spatial resolution observations to securely determine black hole masses, as there could be systematic differences in the black hole scaling relations between these types of galaxies and the BCGs/giant ellipticals, thereby implying different pathways for black hole and galaxy growth.
Abstract
We carried out spectroscopic monitoring of 21 low-redshift Seyfert 1 galaxies using the Kast double spectrograph on the 3 m Shane telescope at Lick Observatory from 2016 April to 2017 May. ...Targeting active galactic nuclei (AGNs) with luminosities of
λ
L
λ
(5100 Å) ≈ 10
44
erg s
−1
and predicted H
β
lags of ∼20–30 days or black hole masses of 10
7
–10
8.5
M
⊙
, our campaign probes luminosity-dependent trends in broad-line region (BLR) structure and dynamics as well as to improve calibrations for single-epoch estimates of quasar black hole masses. Here we present the first results from the campaign, including H
β
emission-line light curves, integrated H
β
lag times (8–30 days) measured against
V
-band continuum light curves, velocity-resolved reverberation lags, line widths of the broad H
β
components, and virial black hole mass estimates (10
7.1
–10
8.1
M
⊙
). Our results add significantly to the number of existing velocity-resolved lag measurements and reveal a diversity of BLR gas kinematics at moderately high AGN luminosities. AGN continuum luminosity appears not to be correlated with the type of kinematics that its BLR gas may exhibit. Follow-up direct modeling of this data set will elucidate the detailed kinematics and provide robust dynamical black hole masses for several objects in this sample.
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