THE MOLECULAR BARYON CYCLE OF M82 Chisholm, John; Matsushita, Satoki
The Astrophysical journal,
10/2016, Volume:
830, Issue:
2
Journal Article
Peer reviewed
Open access
ABSTRACT Baryons cycle into galaxies from the intergalactic medium and are converted into stars; a fraction of the baryons are ejected out of galaxies by stellar feedback. Here we present new ...high-resolution (3 9; 68 pc) 12CO(2-1) and 12CO(3-2) images that probe these three stages of the baryon cycle in the nearby starburst M82. We combine these new observations with previous 12CO(1-0) and Fe ii images to study the physical conditions within the molecular gas. Using a Bayesian analysis and the radiative transfer code RADEX, we model temperatures and densities of molecular hydrogen, as well as column densities of CO. Besides the disk, we concentrate on two regions within the galaxy: an expanding super-bubble and the base of a molecular streamer. Shock diagnostics, kinematics, and optical extinction suggest that the streamer is an inflowing filament, with a mass inflow rate of molecular gas of 3.5 yr−1. We measure the mass outflow rate of molecular gas of the expanding super-bubble to be 17 yr−1, five times higher than the inferred inflow rate and 1.3 times the star formation rate of the galaxy. The high mass outflow rate and large star formation rate will deplete the galaxy of molecular gas within eight million years, unless there are additional sources of molecular gas.
ABSTRACT The central image of a strongly lensed background source places constraints on the foreground lens galaxy's inner mass profile slope, core radius, and mass of its nuclear supermassive black ...hole. Using high-resolution long-baseline Atacama Large Millimeter/submillimeter Array (ALMA) observations and archival Hubble Space Telescope (HST) imaging, we model the gravitational lens H-ATLAS J090311.6+003906 (also known as SDP.81) and search for the demagnified central image. There is central continuum emission from the lens galaxy's active galactic nucleus (AGN) but no evidence of the central lensed image in any molecular line. We use the CO maps to determine the flux limit of the central image excluding the AGN continuum. We predict the flux density of the central image and use the limits from the ALMA data to constrain the innermost mass distribution of the lens. For a power-law profile with a core radius of 0 15 measured from HST photometry of the lens galaxy assuming that the central flux is attributed to the AGN, we find that a black hole mass of is preferred. Deeper observations with a detection of the central image will significantly improve the constraints of the innermost mass distribution of the lens galaxy.
Abstract
The lensing power spectra for gravitational potential, astrometric shift, and convergence perturbations are powerful probes to investigate dark matter structures on small scales. We report ...the first lower and upper bounds of these lensing power spectra on angular scale ∼1″ toward the anomalous quadruply lensed quasar MG J0414+0534 at a redshift
z
= 2.639. To obtain the spectra, we conducted observations of MG J0414+0534 using the Atacama Large Millimeter/submillimeter Array with high angular resolution (0.″02–0.″05). We developed a new partially nonparametric method in which Fourier coefficients of potential perturbation are adjusted to minimize the difference between linear combinations of weighted mean de-lensed images. Using positions of radio-jet components, extended dust emission on scales >1 kpc, and mid-infrared flux ratios, the range of measured convergence, astrometric shift, and potential powers at an angular scale of ∼1.″1 (corresponding to an angular wavenumber of
l
= 1.2 × 10
6
or ∼9 kpc in the primary lens plane) within 1
σ
are Δ
κ
= 0.021–0.028, Δ
α
= 7–9 mas, and Δ
ψ
= 1.2–1.6 mas
2
, respectively. Our result is consistent with the predicted abundance of halos in the line of sight and subhalos in cold dark matter models. Our partially nonparametric lens models suggest the presence of a clump in the vicinity of object Y, a possible dusty dwarf galaxy, and some small clumps in the vicinity of other lensed quadruple images. Although much fainter than the previous report, we detected weak continuum emission possibly from object Y with a peak flux of ∼100
μ
Jy beam
−1
at the ∼4
σ
level.
We present an analysis of the Atacama Large Millimeter/submillimeter Array long baseline science verification data of the gravitational lens system SDP.81. We fit the positions of the brightest ...clumps at redshift z = 3.042 and a possible active galactic nucleus component of the lensing galaxy at redshift z = 0.2999 in the band 7 continuum image using a canonical lens model, a singular isothermal ellipsoid plus an external shear. Then, we measure the ratio of fluxes in some apertures at the source plane where the lensed images are inversely mapped. We find that the aperture flux ratios of band 7 continuum image are perturbed by 10–20 per cent with a significance at 2 ∼ 3σ level. Moreover, we measure the astrometric shifts of multiply lensed images near the caustic using the CO(8–7) line. Using a lens model best fitted to the band 7 continuum image, we reconstruct the source image of the CO(8–7) line by taking linear combination of inverted quadruply lensed images. At the 50th channel (rest-frame velocity 28.6 km s−1) of the CO(8–7) line, we find an imprint of astrometric shifts of the order of 0.01 arcsec in the source image. Based on a semi-analytic calculation, we find that the observed anomalous flux ratios and the astrometric shifts can be explained by intergalactic dark structures in the line of sight. A compensated homogeneous spherical clump with a mean surface mass density of the order of 108 M⊙ h
−1 arcsec−2 can explain the observed anomaly and astrometric shifts simultaneously.
We report on the first bird's-eye view of the innermost accretion disk around the high-mass protostellar object G353.273+0.641, taken by Atacama Large Millimeter/submillimeter Array long baselines. ...The disk traced by dust continuum emission has a radius of 250 au, surrounded by the infalling rotating envelope traced by thermal CH3OH lines. This disk radius is consistent with the centrifugal radius estimated from the specific angular momentum in the envelope. The lower-limit envelope mass is ∼5-7 M☉ and accretion rate onto the stellar surface is 3 × 10−3 M☉ yr−1 or higher. The expected stellar age is well younger than 104 yr, indicating that the host object is one of the youngest high-mass objects at present. The disk mass is 2-7 M☉, depending on the dust opacity index. The estimated Toomre's Q parameter is typically 1-2 and can reach 0.4 at the minimum. These Q values clearly satisfy the classical criteria for gravitational instability, and are consistent with recent numerical studies. Observed asymmetric and clumpy structures could trace a spiral arm and/or disk fragmentation. We found that 70% of the angular momentum in the accretion flow could be removed via the gravitational torque in the disk. Our study has indicated that the dynamical nature of a self-gravitating disk could dominate the early phase of high-mass star formation. This is remarkably consistent with the early evolutionary scenario of a low-mass protostar.
We used the Atacama Large Millimeter/submillimeter Array to map 12CO(J = 1-0), 12CO(J = 2-1), 12CO(J = 3-2), 13CO(J = 2-1), and C i(3P1-3P0) emission lines around the type 1 active galactic nucleus ...(AGN) of NGC 7469 (z = 0.0164) at ∼100 pc resolutions. The CO lines are bright in both the circumnuclear disk (central ∼300 pc) and the surrounding starburst (SB) ring (∼1 kpc diameter), with two bright peaks on either side of the AGN. By contrast, the C i(3P1-3P0) line is strongly peaked on the AGN. Consequently, the brightness temperature ratio of C i(3P1-3P0) to 13CO(2-1) is ∼20 at the AGN, as compared to ∼2 in the SB ring. Our local thermodynamic equilibrium (LTE) and non-LTE models indicate that the enhanced line ratios (or C i enhancement) are due to an elevated C0/CO abundance ratio (∼3-10) and temperature (∼100-500 K) around the AGN as compared to the SB ring (abundance ratio ∼1, temperature 100 K), which accords with the picture of the X-ray-dominated region. Based on dynamical modelings, we also provide CO(1-0)-to- and C i(3P1-3P0)-to-molecular mass conversion factors at the central ∼100 pc of this AGN as CO = 4.1 and C i = 4.4 M (K km s−1 pc2)−1, respectively. Our results suggest that the C i enhancement is potentially a good marker of AGNs that could be used in a new submillimeter diagnostic method toward dusty environments.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations at 233, 678, and 870 GHz of the Galactic Center black hole, Sagittarius A*. These observations reveal a flat spectrum over ...this frequency range with spectral index −0.3, where the flux density S ∝ . We model the submillimeter and far-infrared spectrum with a one-zone synchrotron model of thermal electrons. We infer electron densities n = (2-5) × 106 cm−3, electron temperatures Te = (1-3) × 1011 K, and magnetic field strength B = 10-50 G. The parameter range can be further constrained using the observed quiescent X-ray luminosity. The flat submillimeter spectrum results in a high electron temperature and implies that the emitting electrons are efficiently heated. We also find that the emission is most likely optically thin at 233 GHz. These results indicate that millimeter and submillimeter wavelength very long baseline interferometry of Sgr A* including those of the Event Horizon Telescope should see a transparent emission region down to event horizon scales.
We report our high-resolution (0 03-0 07) Atacama Large Millimeter/submillimeter Array (ALMA) imaging of the quadruply lensed radio-loud quasar MG J0414+0534 at redshift z = 2.639 in the continuum ...and the broad CO(11−10) line at ∼340 GHz. With the help of strong lensing magnification and ALMA's high resolution, we succeeded in resolving the jet/dust and CO gas in the quasar host galaxy, both extending up to ∼1 kpc, with a resolution of ∼50 pc for the first time. Both the continuum emission and the CO(11−10) line have a similar bimodal structure aligned with the quasar jets (∼200 pc) observed by Very Long Baseline Interferometry at 5 and 8.4 GHz. The CO gas in the vicinity of both the eastern and western jet components at the location of ∼80 pc from the quasar core are moving at high velocities, up to 600 km s−1 relative to the core. The observed features show clear evidence of strong interaction between the jets and interstellar medium (ISM). High temperature and high-density environments in the ISM of the quasar host galaxy, as suggested from CO line ratios, also support this result. The small scale of the jets, the jet-ISM interaction, and the continuum spectral energy distribution of this source indicate that we are watching the infancy stage of quasar radio activity.
ABSTRACT
We present a supermassive black hole (SMBH) mass measurement in the Seyfert 1 galaxy NGC 7469 using Atacama Large Millimeter/submillimeter Array (ALMA) observations of the atomic-CI(1–0) and ...molecular-12CO(1–0) emission lines at the spatial resolution of ≈0${_{.}^{\prime\prime}}$3 (or ≈100 pc). These emissions reveal that NGC 7469 hosts a circumnuclear gas disc (CND) with a ring-like structure and a two-arm/bi-symmetric spiral pattern within it, surrounded by a starbursting ring. The CND has a relatively low σgas/V ≈ 0.35 (r ≲ 0${_{.}^{\prime\prime}}$5) and ≈0.19 (r > 0${_{.}^{\prime\prime}}$5), suggesting that the gas is dynamically settled and suitable for dynamically deriving the mass of its central source. As is expected from X-ray dominated region (XDR) effects that dramatically increase an atomic carbon abundance by dissociating CO molecules, we suggest that the atomic CI(1–0) emission is a better probe of SMBH masses than CO emission in active galactic nuclei (AGNs). Our dynamical model using the CI(1–0) kinematics yields a $M_{\rm BH}=1.78^{+2.69}_{-1.10}\times 10^7$ M⊙ and $M/L_{\rm F547M}=2.25^{+0.40}_{-0.43}$ (M⊙/L⊙). The model using the 12CO(1–0) kinematics also gives a consistent MBH with a larger uncertainty, up to an order of magnitude, i.e. $M_{\rm BH}=1.60^{+11.52}_{-1.45}\times 10^7$ M⊙. This newly dynamical MBH is ≈2 times higher than the mass determined from the reverberation mapped (RM) method using emissions arising in the unresolved broad-line region (BLR). Given this new MBH, we are able to constrain the specific RM dimensionless scaling factor of $f=7.2^{+4.2}_{-3.4}$ for the AGN BLR in NGC 7469. The gas within the unresolved BLR thus has a Keplerian virial velocity component and the inclination of $i\approx {11.0^\circ }_{-2.5}^{+2.2}$, confirming its face-on orientation in a Seyfert 1 AGN by assuming a geometrically thin BLR model.
ABSTRACT Compiling data from literature and the Atacama Large Millimeter/submillimeter Array archive, we show enhanced HCN(4-3)/HCO+(4-3) and/or HCN(4-3)/CS(7-6) integrated intensity ratios in ...circumnuclear molecular gas around active galactic nuclei (AGNs) compared to those in starburst (SB) galaxies (submillimeter HCN enhancement). The number of sample galaxies is significantly increased from our previous work. We expect that this feature could potentially be an extinction-free energy diagnostic tool of nuclear regions of galaxies. Non-LTE radiative transfer modelings of the above molecular emission lines involving both collisional and radiative excitation, as well as a photon trapping effect, were conducted to investigate the cause of the high line ratios in AGNs. As a result, we found that enhanced abundance ratios of HCN to HCO+ and HCN to CS in AGNs as compared to SB galaxies by a factor of a few to even 10 are a plausible explanation for the submillimeter HCN enhancement. However, a counterargument of a systematically higher gas density in AGNs than in SB galaxies can also be a plausible scenario. Although we cannot fully distinguish these two scenarios at this moment owing to an insufficient amount of multi-transition, multi-species data, the former scenario is indicative of abnormal chemical composition in AGNs. Regarding the actual mechanism to realize the composition, we suggest that it is difficult with conventional gas-phase X-ray-dominated region ionization models to reproduce the observed high line ratios. We might have to take into account other mechanisms such as neutral-neutral reactions that are efficiently activated in high-temperature environments and/or mechanically heated regions to further understand the high line ratios in AGNs.
PDF
