Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA spectacular outflow in an obscured quasar
382
0
0.0
(
0
)
Authors
Jenny E. Greene
Ask ChatGPT about the research
No Arabic abstract
SDSS J1356+1026 is a pair of interacting galaxies at redshift z=0.123 that hosts a luminous obscured quasar in its northern nucleus. Here we present two long-slit Magellan LDSS-3 spectra that reveal a pair of symmetric ~10 kpc-size outflows emerging from this nucleus, with observed expansion velocities of ~250 km/s in projection. We present a kinematic model of these outflows and argue that the deprojected physical velocities of expansion are likely ~1000 km/s and that the kinetic energy of the expanding shells is likely 10^44-10^45 erg/s, with an absolute minimum of >10^42 erg/s. Although a radio counterpart is detected at 1.4GHz, it is faint enough that the quasar is considered to be radio-quiet by all standard criteria, and there is no evidence of extended emission due to radio lobes, whether aged or continuously powered by an ongoing jet. We argue that the likely level of star formation is probably insufficient to power the observed energetic outflow and that SDSS J1356+1026 makes a strong case for radio-quiet quasar feedback. In further support of this hypothesis, polarimetric observations show that the direction of quasar illumination is coincident with the direction of the outflow.
rate research
Read More
We present new detections of the CO(5-4), CO(7-6), [CI](1-0) and [CI](2-1) molecular and atomic line transitions towards the unlensed, obscured quasar AMS12 (z=2.7672), observed with the IRAM PdBI. This is the first unlensed, high redshift source to have both [CI] transitions detected. Continuum measurements between 70 $mu$m and 3 mm are used to constrain the FIR SED, and we find a best fit FIR luminosity of log[Lfir/Lsol] = 13.5+/-0.1, dust temperature T_d = 88+/-8 K and emissivity index {beta} = 0.6+/-0.1. The highly-excited molecular gas probed by CO(3-2), (5-4) and (7-6), is modelled with large velocity gradient (LVG) models. The gas kinetic temperature T_g, density n(H2), and the characteristic size r0, are determined using the dust temperature from the FIR SED as a prior for the gas temperature. The best fitting parameters are T_g = 90+/-8 K, n(H2) = 10^(3.9+/-0.1) cm^(-3) and r0 = 0.8+/-0.04 kpc. The ratio of the [CI] lines gives a [CI] excitation temperature of 43+/-10 K, indicating the [CI] and the high-excitation CO are not in thermal equilibrium. The [CI] excitation temperature is below that of T_d and T_g of the high-excitation CO, perhaps because [CI] lies at a larger radius where there may also be a large reservoir of CO at a cooler temperature, perhaps detectable through the CO(1-0). Using the [CI](1-0) line we can estimate the strength of the CO(1-0) line and hence the gas mass. This suggests that a significant fraction (~30%) of the molecular gas is missed from the high-excitation line analysis. The Eddington limited black hole mass is found from the bolometric luminosity to be Mbh >~ 1.5x10^9 Msol. Along with the stellar mass of 3x10^11 Msol, these give a black hole - bulge mass ratio of Mbh/Mbulge >~ 0.005. This is in agreement with studies on the evolution of the Mbh/Mbulge relationship at high redshifts, which find a departure from the local value ~0.002.
We imaged with ALMA and ARGOS/LUCI the molecular gas and the dust and stellar continuum in XID2028, an obscured QSO at z=1.593, where the presence of a massive outflow in the ionized gas component traced by the [O III]5007 emission has been resolved up to 10 kpc. This target represents a unique test case to study QSO feedback in action at the peak epoch of AGN-galaxy coevolution. The QSO has been detected in the CO(5-4) transition and in the 1.3mm continuum, at ~30 and ~20 {sigma} significance respectively, with both emissions confined in the central (<4 kpc) radius area. Our analysis suggests the presence of a fast rotating molecular disc (v~400 km/s) on very compact scales, and well inside the galaxy extent seen in the rest-frame optical light (~10 kpc, as inferred from the LUCI data). Adding available measurements in additional two CO transitions, CO(2-1) and CO(3-2), we could derive a total gas mass of ~10$^{10}$ M$_odot$, thanks to a critical assessment of CO excitation and the comparison with Rayleigh-Jeans continuum estimate. This translates into a very low gas fraction (<5%) and depletion time scales of 40-75 Myr, reinforcing the result of atypical gas consumption conditions in XID2028, possibly due to feedback effects on the host galaxy. Finally, we also detect at ~5{sigma} the presence of high velocity CO gas, which we interpret as a signature of galaxy-scale molecular outflow, spatially coincident with the ionised gas outflow. XID2028 represents therefore a unique case where the measurement of total outflowing mass (~500-800 M$_odot$/yr) including the molecular and atomic components, in both the ionised and neutral phases, has been attempted for a high-z QSO.
BHR 71 is a well isolated Bok globule located at ~200 pc, which harbours a highly collimated bipolar outflow. The outflow is driven by a very young Class 0 protostar with a luminosity of ~9 L_sun. It is one of a very small number that show enhanced abundances of a number of molecular species, notably SiO and CH3OH, due to shock processing of the ambient medium. In this paper the properties of the globule and outflow are discussed.
In active galactic nuclei (AGN)-galaxy co-evolution models, AGN winds and outflows are often invoked to explain why super-massive black holes and galaxies stop growing efficiently at a certain phase of their lives. They are commonly referred to as the leading actors of feedback processes. Evidence of ultra-fast (v>0.05c) outflows in the innermost regions of AGN has been collected in the past decade by sensitive X-ray observations for sizable samples of AGN, mostly at low redshift. Here we present ultra-deep XMM-Newton and Chandra spectral data of an obscured (Nh~2x10^{23} cm^-2), intrinsically luminous (L2-10keV~4x10^{44} erg/s) quasar (named PID352) at z~1.6 (derived from the X-ray spectral analysis) in the Chandra Deep Field-South. The source is characterized by an iron emission and absorption line complex at observed energies of E~2-3 keV. While the emission line is interpreted as being due to neutral iron (consistent with the presence of cold absorption), the absorption feature is due to highly ionized iron transitions (FeXXV, FeXXVI) with an outflowing velocity of 0.14^{+0.02}_{-0.06}c, as derived from photoionization models. The mass outflow rate - ~2 Msun/yr - is similar to the source accretion rate, and the derived mechanical energy rate is ~9.5x10^{44} erg/s, corresponding to 9% of the source bolometric luminosity. PID352 represents one of the few cases where indications of X-ray outflowing gas have been observed at high redshift thus far. This wind is powerful enough to provide feedback on the host galaxy.
We announce the discovery of a quasar behind the disk of M31, which was previously classified as a remarkable nova in our neighbour galaxy. The paper is primarily aimed at the outburst of J004457+4123 (Sharov 21), with the first part focussed on the optical spectroscopy and the improvement in the photometric database. Both the optical spectrum and the broad band spectral energy distribution of Sharov 21 are shown to be very similar to that of normal, radio-quiet type 1 quasars. We present photometric data covering more than a century and resulting in a long-term light curve that is densely sampled over the past five decades. The variability of the quasar is characterized by a ground state with typical fluctuation amplitudes of ~0.2 mag around B~20.5, superimposed by a singular flare of ~2 yr duration (observer frame) with the maximum at 1992.81 where the UV flux has increased by a factor of ~20. The total energy in the flare is at least three orders of magnitudes higher than the radiated energy of the most luminous supernovae, provided that it comes from an intrinsic process and the energy is radiated isotropically. The profile of the flare light curve appears to be in agreement with the standard predictions for a stellar tidal disruption event where a ~10 M_sun giant star was shredded in the tidal field of a ~2...5 10^8 M_sun black hole. The short fallback time derived from the light curve requires an ultra-close encounter where the pericentre of the stellar orbit is deep within the tidal disruption radius. Gravitational microlensing provides an alternative explanation, though the probability of such a high amplification event is very low.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
