Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userA giant Ly$alpha$ nebula and a small-scale clumpy outflow in the system of the exotic quasar J0952+0114 unveiled by MUSE
83
0
0.0
(
0
)
Added by
Raffaella Anna Marino
Publication date
2019
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
The well-known quasar SDSS J095253.83+011421.9 (J0952+0114) at z=3.02 has one of the most peculiar spectra discovered so far, showing the presence of narrow Ly$alpha$ and broad metal emission lines. Although recent studies have suggested that a Proximate Damped Ly$alpha$ system (PDLA) causes this peculiar spectrum, the origin of the gas associated with the PDLA is unknown. Here we report the results of MUSE observations that reveal a new giant ($approx$ 100 physical kpc) Lyman $alpha$ nebula. The detailed analysis of the Ly$alpha$ velocity, velocity dispersion, and surface brightness profiles suggests that the J0952+0114 Ly$alpha$ nebula shares similar properties of other QSO nebulae previously detected with MUSE, implying that the PDLA in J0952+0144 is covering only a small fraction of the QSO emission solid angle. We also detected bright and spectrally narrow CIV$lambda$1550 and HeII$lambda$1640 extended emission around J0952+0114 with velocity centroids similar to the peak of the extended and central narrow Ly$alpha$ emission. The presence of a peculiarly bright, unresolved, and relatively broad HeII$lambda$1640 emission in the central region at exactly the same PDLA redshift hints at the possibility that the PDLA originates in a clumpy outflow with a bulk velocity of about 500 km/s. The smaller velocity dispersion of the large scale Ly$alpha$ emission suggests that the high-speed outflow is confined to the central region. Lastly, the derived spatially resolved HeII/Ly$alpha$ and CIV/Ly$alpha$ maps show a positive gradient with the distance to the QSO hinting at a non-homogeneous ionization parameter distribution.
rate research
Read More
With a projected size of about 450 kpc at z~2.3, the Slug Ly-alpha nebula is a rare laboratory to study, in emission, the properties of the intergalactic gas in the Cosmic Web. Since its discovery, the Slug has been the subject of several spectroscopic follow-ups to constrain the properties of the emitting gas. Here we report the results of a deep MUSE integral-field spectroscopic search for non-resonant, extended HeII1640 and metal emission. Extended HeII radiation is detected on scales of about 100 kpc, but only in some regions associated with the bright Ly-alpha emission and a continuum-detected source, implying large and abrupt variations in the line ratios across adjacent regions in projected space. The recent detection of associated H-alpha emission and similar abrupt variations in the Ly-alpha kinematics, strongly suggest that the HeII/Ly-alpha gradient is due to large variations in the physical distances between the associated quasar and these regions. This implies that the overall length of the emitting structure could extend to physical Mpc scales and be mostly oriented along our line of sight. At the same time, the relatively low HeII/Ly-alpha values suggest that the emitting gas has a broad density distribution that - if expressed in terms of a lognormal - implies dispersions as high as those expected in the interstellar medium of galaxies. These results strengthen the possibility that the density distribution of intergalactic gas at high-redshift is extremely clumpy and multiphase on scales below our current observational spatial resolution of a few physical kpc.
We present deep MUSE integral-field unit (IFU) spectroscopic observations of the giant (~150 x 80 kpc) Ly-alpha halo around the z=4.1 radio galaxy TNJ J1338-1942. This 9-hr observation maps the two-dimensional kinematics of the Ly-alpha emission across the halo. We identify two HI absorbers which are seen against the Ly-alpha emission, both of which cover the full 150 x 80 kpc extent of the halo and so have covering fractions ~1. The stronger and more blue-shifted absorber (dv~1200 km/s) has dynamics that mirror that of the underlying halo emission and we suggest that this high column material (n(HI) ~ 10^19.4 /cm^2), which is also seen in CIV absorption, represents an out-flowing shell that has been driven by the AGN (or star formation) within the galaxy. The weaker (n(HI)~10^14 /cm^2) and less blue shifted (dv~500 km/s) absorber most likely represents material in the cavity between the out-flowing shell and the Ly-alpha halo. We estimate that the mass in the shell must be of order 10^10 Msol -- a significant fraction of the ISM from a galaxy at z=4. The large scales of these coherent structures illustrate the potentially powerful influence of AGN feedback on the distribution and energetics of material in their surroundings. Indeed, the discovery of high-velocity (~1000 km/s), group-halo-scale (i.e. >150 kpc) and mass-loaded winds in the vicinity of the central radio source are broadly in agreement with the requirements of models that invoke AGN-driven outflows to regulate star formation and black-hole growth in massive galaxies at early times.
We exploit wide-field Ly$alpha$ imaging with Subaru to probe the environment around TN J1338-1942, a powerful radio galaxy with a >100 kpc Ly$alpha$ halo at z=4.11. We used a sample of Ly$alpha$ emitters (LAEs) down to $log(L_{rm Lyalpha} [erg, s^{-1}])sim 42.8$ to measure the galaxy density around TNJ1338, compared to a control sample from a blank field taken with the same instrument. We found that TNJ1338 resides in a region with a peak overdensity of $delta_{rm LAE}=2.8pm 0.5$ on scales of $8, h^{-1}rm Mpc$ (on the sky) and $112, h^{-1}rm Mpc$ (line of sight) in comoving coordinates. Adjacent to this overdensity, we found a strong underdensity where virtually no LAEs are detected. We used a semi-analytical model of LAEs derived from the Millennium Simulation to compare our results with theoretical predictions. While the theoretical density distribution is consistent with the blank field, overdense regions such as that around TNJ1338 are very rare, with a number density of $6.4times 10^{-8}rm Mpc^{-3}$ (comoving), corresponding to the densest < 0.4 percentile at $zsimeq 4.1$. We also found that the Ly$alpha$ luminosity function in the TNJ1338 field differs from that in the blank field: the number of bright LAEs ($log(L_{rm Lyalpha}[erg,s^{-1}]) gtrsim 43.3$) is enhanced, while the number of fainter LAEs is relatively suppressed. These results suggest that some powerful radio galaxies associated with Ly$alpha$ nebulae reside in extreme overdensities on $sim 3$--$6, rm Mpc$ scales, where star-formation and AGN activity may be enhanced via frequent galaxy mergers or high rates of gas accretion from the surroundings.
Direct Ly $alpha$ imaging of intergalactic gas at $zsim2$ has recently revealed giant cosmological structures around quasars, e.g. the Slug Nebula (Cantalupo et al. 2014). Despite their high luminosity, the detection rate of such systems in narrow-band and spectroscopic surveys is less than 10%, possibly encoding crucial information on the distribution of gas around quasars and the quasar emission properties. In this study, we use the MUSE integral-field instrument to perform a blind survey for giant Ly $alpha$ nebulae around 17 bright radio-quiet quasars at $3<z<4$ that does not suffer from most of the limitations of previous surveys. After data reduction and analysis performed with specifically developed tools, we found that each quasar is surrounded by giant Ly $alpha$ nebulae with projected sizes larger than 100 physical kpc and, in some cases, extending up to 320 kpc. The circularly averaged surface brightness profiles of the nebulae appear very similar to each other despite their different morphologies and are consistent with power laws with slopes $approx-1.8$. The similarity between the properties of all these nebulae and the Slug Nebula suggests a similar origin for all systems and that a large fraction of gas around bright quasars could be in a relatively cold (T$sim$10$^4$K) and dense phase. In addition, our results imply that such gas is ubiquitous within at least 50 kpc from bright quasars at $3<z<4$ independently of the quasar emission opening angle, or extending up to 200 kpc for quasar isotropic emission.
We use spatially extended measurements of Ly$alpha$ as well as less optically thick emission lines from an $approx$80 kpc Ly$alpha$ nebula at $zapprox1.67$ to assess the role of resonant scattering and to disentangle kinematic signatures from Ly$alpha$ radiative transfer effects. We find that the Ly$alpha$, CIV, HeII, and CIII] emission lines all tell a similar story in this system, and that the kinematics are broadly consistent with large-scale rotation. First, the observed surface brightness profiles are similar in extent in all four lines, strongly favoring a picture in which the Ly$alpha$ photons are produced in situ instead of being resonantly scattered from a central source. Second, we see low kinematic offsets between Ly$alpha$ and the less optically thick HeII line ($sim$100-200 km s$^{-1}$), providing further support for the argument that the Ly$alpha$ and other emission lines are all being produced within the spatially extended gas. Finally, the full velocity field of the system shows coherent velocity shear in all emission lines: $approx$500 km s$^{-1}$ over the central $approx$50 kpc of the nebula. The kinematic profiles are broadly consistent with large-scale rotation in a gas disk that is at least partially stable against collapse. These observations suggest that the Ly$alpha$ nebula represents accreting material that is illuminated by an offset, hidden AGN or distributed star formation, and that is undergoing rotation in a clumpy and turbulent gas disk. With an implied mass of M(<R=20 kpc)$sim3times10^{11}$ $M_{odot}$, this system may represent the early formation of a large Milky Way mass galaxy or galaxy group.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
