Giant Nebula Research Articles

AGN feedback can produce metal enrichment on galaxy scales

Giant ($>$100 kpc) nebulae associated with active galaxies provide rich information about the circumgalactic medium around galaxies, its link with the interstellar medium of the hosts, and the mechanisms involved in their evolution. We have studied the giant nebula associated with the Teacup ($z$=0.085) quasar based on VLT MUSE integral field spectroscopy to investigate whether the well-known giant (sim 10 kpc) active galactic nucleus (AGN) -induced outflow has an impact on the distribution of heavy elements in and outside the host galaxy. We have mapped the oxygen and nitrogen gas relative abundances (O/H and N/O) in two spatial dimensions across the giant nebula and within the galaxy by means of comparing emission line ratios with photoionisation model predictions. The widely studied AGN-driven outflow responsible for the sim 10 kpc ionised bubble is enhancing the gas metal abundance up to sim 10 kpc from the AGN. O/H is solar or slightly higher at the edges of the bubble, in comparison with the subsolar abundances across the rest of the nebula median (O/Hsim 0.63 (O/H)$_ odot AGN feedback can produce metal enrichment at large extranuclear distances in galaxies (ge 10 kpc).

Serendipitous Catch of a Giant Jellyfish: An Ionized Nebula around 3C 275.1 with 170 kpc Long Tails

3C 275.1 is a blue quasar at z = 0.55522, hosting powerful outflows and residing in a complex environment. We present a serendipitously detected giant nebula surrounding 3C 275.1, which shows morphological features resembling those of objects known as “jellyfish galaxies,” with extremely long tails of ionized gas extending to 170 kpc in projection. We analyze its optical spectra taken by MUSE on the Very Large Telescope. The brighter part of this giant nebula exceeds 100 kpc, and its rotation curve does not flatten out, making it very different from those of normal spiral galaxies. This system shares some characteristics common to those formed via ram pressure stripping (RPS), yet its long narrow tails and higher ionization are unusual compared to known tails in jellyfish galaxies, not fully consistent with a simple RPS scenario. Our photoionization simulation and the inferred short recombination timescale both suggest that, besides the quasar 3C 275.1, an extra source of ionization is necessary to keep the gas ionized at such a distance from the nucleus, which could be related to RPS, tidal interaction, or active galactic nucleus outflow, providing new evidence of active dynamical interaction of a galaxy with the intracluster medium.

The essential sun: Its past, present, and future

The sun provides warmth and light essential to human life, making it important to investigate its formation, current state, and future evolution. This article includes information on the formation of the sun and an overview of its current state. The sun formed about 4.6 billion years ago from a giant nebula in one of the spiral arms of the Milky Way galaxy, after which the solar system formed from. As for its structure, the sun consists of six layers: core, radiative zone, convection zone, photosphere, chromosphere, and corona. The sun is a main sequence star and is situated at a considerable distance from the earth. This distance is calculated using the parallax method, which involves measuring the parallax angle and applying trigonometry. Another approach to determine the distance is by utilizing Kepler's Third Law. The sun continually undergoes fusion in its core due to specific conditions that allow for fusion reactions to occur, including extremely high temperatures, high density, and a suitable containment vessel. In the future, the sun will evolve into a red giant star before ultimately becoming a white dwarf star. Eventually, the earth will be engulfed by the sun as the sun evolves.

The first comprehensive study of a giant nebula around a radio-quiet quasar in the z < 1 Universe

ABSTRACT We present the first comprehensive study of a giant, ≈70 kpc-scale nebula around a radio-quiet quasar at z < 1. The analysis is based on deep integral field spectroscopy with Multi-Unit Spectroscopic Explorer of the field of HE 0238−1904, a luminous quasar at z = 0.6282. The nebula emits strongly in [O ii], $\rm H \beta$, and [O iii], and the quasar resides in an unusually overdense environment for a radio-quiet system. The environment likely consists of two groups which may be merging, and in total have an estimated dynamical mass of Mdyn ≈ 4 × 1013 to 1014 M⊙. The nebula exhibits largely quiescent kinematics and irregular morphology. The nebula may arise primarily through interaction-related stripping of circumgalactic and interstellar medium (CGM/ISM) of group members, with some potential contributions from quasar outflows. The simultaneous presence of the giant nebula and a radio-quiet quasar in a rich environment suggests a correlation between such circum-quasar nebulae and environmental effects. This possibility can be tested with larger samples. The upper limits on the electron number density implied by the [O ii] doublet ratio range from $\log (n_{\rm e, [O\,{\small II}]} /\mathrm{cm}^{-3})<1.2$ to 2.8. However, assuming a constant quasar luminosity and negligible projection effects, the densities implied from the measured line ratios between different ions (e.g. [O ii], [O iii], and [Ne v]) and photoionization simulations are often 10−400 times larger. This large discrepancy can be explained by quasar variability on a time-scale of ≈104−105 yr.

Integral Field Spectroscopy of the cometary starburst galaxy NGC 4861

ABSTRACT Using the PMAS Integral Field Unit on the Calar Alto 3.5 m telescope, we observed the southern component (Markarian 59) of the ‘cometary’ starburst galaxy NGC 4861. Mrk 59 is centred on a giant nebula and concentration of stars 1 kpc in diameter. Strong $\rm H\,\alpha$ emission points to a star-formation rate (SFR) at least 0.47 $\rm M_{\odot }\, yr^{-1}$. Mrk 59 has a very high [O iii] $\rm \lambda 5007/H\,\beta$ ratio, reaching 7.35 in the central nebula, with a second peak at a star-forming hotspot further north. Fast outflows are not detected but nebular motion and galaxy rotation produce relative velocities up to 40 km $\rm s^{-1}$. Spectral analysis of different regions with ‘Fitting Analysis using Differential evolution Optimization’ (FADO) finds that the stars in the central and ‘spur’ nebulae are very young, $\rm \le 125~Myr$ with a large $\rm \lt 10~Myr$ contribution. Older stars ($\rm \sim 1~Gyr$) make up the northern disk component, while the other regions show mixtures of 1 Gyr age with very young stars. This and the high specific SFR $\rm \sim 3.5~Gyr^{-1}$ imply a bimodal star formation history, with Mrk 59 formed in ongoing starbursts fuelled by a huge gas inflow, turning the galaxy into an asymmetric ‘green pea’ or blue compact dwarf. We map the He ii λ4686 emission, and identify a broad component from the central nebula, consistent with the emission of ∼300 Wolf–Rayet stars. About a third of the He ii λ4686 flux is a narrow line emitted from a more extended area covering the central and spur nebulae, and may have a different origin.

Gas and Stars in the Teacup Quasar Looking with the 6-m Telescope

New results on the radio-quiet type 2 quasar, known as the Teacup galaxy (SDSSJ1430+1339), based on the long-slit and 3D spectroscopic data obtained at the Russian 6-m telescope, are presented. The ionized gas giant nebula, which extends up to r=56 kpc in the [O iii] emission line, was mapped with the scanning Fabry–Perot interferometer. The direct estimation of the emission line ratios confirmed that the giant nebula is ionized by the AGN. Stars in the inner r<5 kpc are significantly younger than the outer host galaxy and have a solar metallicity. The central starburst age (∼1 Gyr) agrees with possible ages for the galactic merger events and the previous episode of the quasar outflow produced two symmetric arcs visible in the [O iii] emission at the distances r= 50–55 kpc. The ionized gas velocity field can be fitted by the model of a circular rotating disk significantly inclined or even polar to the stellar host galaxy.

A Giant Intragroup Nebula Hosting a Damped Absorber at z = 0.313

Abstract This Letter reports the discovery of spatially extended line-emitting nebula, reaching to ≈100 physical kpc (pkpc) from a damped absorber (DLA) at z DLA = 0.313 along the sightline toward quasi-stellar object (QSO) PKS 1127−145 (z QSO = 1.188). This DLA was known to be associated with a galaxy group of dynamical mass M group ∼ 3 × 1012 M ⊙, but its physical origin remained ambiguous. New wide-field integral field observations revealed a giant nebula detected in [O ii], Hβ, [O iii], Hα, and [N ii] emission, with the line-emitting gas following closely the motions of group galaxies. One of the denser streams passes directly in front of the QSO with kinematics that are consistent with the absorption profiles recorded in the QSO echelle spectra. The emission morphology, kinematics, and line ratios of the nebula suggest that shocks and turbulent mixing layers, produced as a result of stripped gaseous streams moving at supersonic speed across the ambient hot medium, contribute significantly to the ionization of the gas. While the DLA may not be associated with any specific detected member of the group, both the kinematic and dust properties are consistent with the DLA originating in streams of gas stripped from sub-L * group members at ≲25 pkpc from the QSO sightline. This study demonstrates that gas stripping in low-mass galaxy groups is effective in releasing metal-enriched gas from star-forming regions, producing absorption systems in QSO spectra, and that combining absorption and emission-line observations provides an exciting new opportunity for studying gas and galaxy co-evolution.

A 100 kpc nebula associated with the ‘Teacup’ fading quasar

We report the discovery of a ~100 kpc ionized nebula associated with the radio quiet type 2 quasar (QSO2) nicknamed the "Teacup" (z=0.085). The giant nebula is among the largest known around active galaxies at any z. We propose that it is part of the circumgalactic medium (CGM) of the QSO2 host, which has been populated with tidal debris by galactic interactions. This rich gaseous medium has been rendered visible due to the illumination by the powerful active nucleus (AGN). Subsolar abundances (~0.5Z(sun)) are tentatively favored by AGN photoionization models. We also report the detection of coronal emission (Fe+6) from the NE bubble, at ~9 kpc from the AGN. The detection of coronal lines at such large distances from the AGN and the [NII]/Halpha, [SII]/Halpha, [OI]/Halpha optical emission line ratios of the giant nebula are consistent with the fading quasar scenario proposed by Gagne et al. (2014). The fading rate appears to have been faster in the last ~46,000 yr. Deep wide field integral field spectroscopy of giant nebulae around powerful AGN such as the "Teacup's" with instruments such as MUSE on VLT opens up a way to detect and study the elusive material from the CGM around massive active galaxies thanks to the illumination by the luminous AGN.

Galaxy evolution. Quasar quartet embedded in giant nebula reveals rare massive structure in distant universe.

All galaxies once passed through a hyperluminous quasar phase powered by accretion onto a supermassive black hole. But because these episodes are brief, quasars are rare objects typically separated by cosmological distances. In a survey for Lyman-α emission at redshift z ≈ 2, we discovered a physical association of four quasars embedded in a giant nebula. Located within a substantial overdensity of galaxies, this system is probably the progenitor of a massive galaxy cluster. The chance probability of finding a quadruple quasar is estimated to be ∼10(-7), implying a physical connection between Lyman-α nebulae and the locations of rare protoclusters. Our findings imply that the most massive structures in the distant universe have a tremendous supply (≃10(11) solar masses) of cool dense (volume density ≃ 1 cm(-3)) gas, which is in conflict with current cosmological simulations.

Spectroscopy of 7 radio-loud QSOs at 2 < z < 6: giant Lyman α emission nebulae accreting on to host galaxies

We performed long-slit optical spectroscopy (GTC-OSIRIS) of 6 radio-loud QSOs at redshifts $2<z<3$, known to have giant ($\sim 50$-100 kpc) Lyman-$\alpha$ emitting nebulae, and detect extended Lyman-$\alpha$ emission for 4, with surface brightness $\sim10^{-16}$ ergs $\rm cm^{-2}s^{-1}arcsec^{-2}$ and line width FWHM 400-1100 (mean 863) km $\rm s^{-1}$. We also observed the $z\simeq 5.9$ radio-loud QSO, SDSS J2228+0110, and find evidence of a $\geq 10$ kpc extended Lyman-$\alpha$ emission nebula, a new discovery for this high-redshift object. Spatially-resolved kinematics of the 5 nebulae are examined by fitting the Lyman-$\alpha$ wavelength at a series of positions along the slit. We found the line-of-sight velocity $\Delta(v)$ profiles to be relatively flat. However, 3 of the nebulae appear systematically redshifted by 250-460 km $\rm s^{-1}$ relative to the Lyman-$\alpha$ line of the QSO (with no offset for the other two), which we argue is evidence for infall. One of these (Q0805+046) had a small ($\sim 100$ km $\rm s^{-1}$) velocity shift across its diameter and a steep gradient at the centre. Differences in line-of-sight kinematics between these 5 giant nebulae and similar nebulae associated with high-redshift radio galaxies (which can show steep velocity gradients) may be due to an orientation effect, which brings infall/outflow rather than rotation into greater prominence for the sources observed `on-axis' as QSOs.

The sources of sodium escaping from Io revealed by spectral high definition imaging

On Jupiter's moon Io, volcanic plumes and evaporating lava flows provide hot gases to form an atmosphere that is subsequently ionized. Some of Io's plasma is captured by the planet's strong magnetic field to form a co-rotating torus at Io's distance; the remaining ions and electrons form Io's ionosphere. The torus and ionosphere are also depleted by three time-variable processes that produce a banana-shaped cloud orbiting with Io, a giant nebula extending out to about 500 Jupiter radii, and a jet close to Io. No spatial constraints exist for the sources of the first two; they have been inferred only from modelling the patterns seen in the trace gas sodium observed far from Io. Here we report observations that reveal a spatially confined stream that ejects sodium only from the wake of the Io-torus interaction, together with a visually distinct, spherically symmetrical outflow region arising from atmospheric sputtering. The spatial extent of the ionospheric wake that feeds the stream is more than twice that observed by the Galileo spacecraft and modelled successfully. This implies considerable variability, and therefore the need for additional modelling of volcanically-driven, episodic states of the great jovian nebula.

VIMOS-VLT spectroscopy of the giant Ly nebulae associated with three z 2.5 radio galaxies

The morphological and spectroscopic properties of the giant (>60 kpc) Lyα nebulae associated with three radio galaxies at z∼ 2.5 (MRC 1558–003, 2025–218 and 0140–257) have been investigated using integral field spectroscopic data obtained with the Visible Multi-Object Spectrograph (VIMOS) on VLT. The morphologies are varied. The nebula of one source has a centrally peaked, rounded appearance. In the other two objects, it consists of two spatial components. The three nebulae are aligned with the radio axis within ≲30°. The total Lyα luminosities are in the range (0.3–3.4) × 1044 erg s−1. The Lyα spectral profile shows strong variation through the nebulae, with full width at half-maximum (FWHM) values in the range ∼400–1500 km s−1 and velocity shifts Voffset∼ 120–600 km s−1. We present an infall model that can successfully explain the morphology, size, surface brightness distribution and the velocity field of the Lyα nebula associated with MRC 1558–003. It can also explain why Lyα is redshifted relative to other emission lines and the FWHM values of the non-resonant He ii line. This adds further support to our previous conclusion that the quiescent giant nebulae associated with this and other high-redshift powerful radio galaxies are in infall. A problem for this model is the difficulty to reproduce the large Lyα FWHM values, which might be the consequence of a different mechanism. We have discovered a giant (∼85 kpc) Lyα nebula associated with the radio galaxy MRC 0140–257 at z= 2.64. It shows strikingly relaxed kinematics (FWHM < 300 km s−1 and Voffset≲ 120 km s−1), unique among high-z (≳2) radio galaxies.

The giant nebulae associated with 3C 227: emission-line profiles and kinematic modelling

The giant nebulae associated with 3C 227: emission-line profiles and kinematic modelling

Unresolved Wind-driven Shells and the Supersonic Velocity Dispersion in Giant H II Regions

The presence of giant shells or loops in giant H II regions is clear witness to the mechanical energy input from massive stars. Here we evaluate the impact that winds may have on the structure of giant nebulae and on their supersonic velocity dispersion. We follow the recent suggestion of Chu and Kennicutt to see whether a combination of a large number of unresolved wind-driven shells caused by massive stars could produce the integrated broad Gaussian profiles typical of giant H II regions. <P />The results, accounting for a wide range of energies, densities, and velocities or ages of the expanding shells, show that supersonic Gaussian profiles may arise only from a collection of unresolved wind-driven shells if the shells present a peculiar velocity distribution which implies a strongly peaked age distribution leading to an awkward star formation history. On the other hand, a uniform distribution of ages produces profiles with a flat-topped core defined by the terminal shell velocity and a steep decay as ν<SUP>-6</SUP>, up to the largest detectable shell speed. Thus, supersonic profiles can arise only if the final speed of the unresolved shells is supersonic. This implies an equally supersonic random speed of motions in the ionized gas disrupting the shells before they slow down to subsonic speeds. It also implies a mechanism, independent of the shells caused by massive stars, responsible for the supersonic stirring of the background medium. These facts, together with the conditions for shells to remain unresolved by present-day devices (energies, final speeds, and ages), indicate that the winds may be produced by low-mass stars. In the latter case, if the sources move supersonically in the gravitational potential of the whole system, they could stir the gas, with their cometary bow shocks, to a velocity dispersion σ<SUB>gas</SUB> σ<SUB>stars</SUB>, causing a supersonic local random speed of motions within the system.