اشترك بالحزمة الذهبية واحصل على وصول غير محدود شمرا أكاديميا
تسجيل مستخدم جديدShocked Molecular Hydrogen in the 3C 326 Radio Galaxy System
120
0
0.0
(
0
)
تأليف
Patrick Ogle
اسأل ChatGPT حول البحث
ﻻ يوجد ملخص باللغة العربية
The Spitzer spectrum of the giant FR II radio galaxy 3C 326 is dominated by very strong molecular hydrogen emission lines on a faint IR continuum. The H2 emission originates in the northern component of a double-galaxy system associated with 3C 326. The integrated luminosity in H2 pure-rotational lines is 8.0E41 erg/s, which corresponds to 17% of the 8-70 micron luminosity of the galaxy. A wide range of temperatures (125-1000 K) is measured from the H2 0-0 S(0)-S(7) transitions, leading to a warm H2 mass of 1.1E9 Msun. Low-excitation ionic forbidden emission lines are consistent with an optical LINER classification for the active nucleus, which is not luminous enough to power the observed H2 emission. The H2 could be shock-heated by the radio jets, but there is no direct indication of this. More likely, the H2 is shock-heated in a tidal accretion flow induced by interaction with the southern companion galaxy. The latter scenario is supported by an irregular morphology, tidal bridge, and possible tidal tail imaged with IRAC at 3-9 micron. Unlike ULIRGs, which in some cases exhibit H2 line luminosities of comparable strength, 3C 326 shows little star-formation activity (~0.1 Msun/yr). This may represent an important stage in galaxy evolution. Starburst activity and efficient accretion onto the central supermassive black hole may be delayed until the shock-heated H2 can kinematically settle and cool
قيم البحث
اقرأ أيضاً
We show the combined spectral analysis of emph{Chandra} high energy transmission grating (HETG) and emph{XMM-Newton} reflection grating spectrometer (RGS) observations of the broad-line radio galaxy 3C 111. The source is known to show excess neutral
absorption with respect to the one estimated from 21 cm radio surveys of atomic H I in the Galaxy. However, previous works were not able to constrain the origin of such absorber as local to our Milky Way or intrinsic to the source ($z = 0.0485$). The high signal-to-noise grating spectra allow us to constrain the excess absorption as due to intervening gas in the Milky Way, and we estimate a time averaged total column density of $N_H = (7.4pm0.1)times 10^{21}$ cm$^{-2}$, a factor of two higher than the tabulated H I value. We recommend to use the total average Galactic column density here estimated when studying 3C 111. The origin of the extra Galactic absorption of $N_H = 4.4times 10^{21}$ cm$^{-2}$ is likely due to molecular gas associated with the Taurus molecular cloud complex toward 3C 111, which is our nearest star-forming region. We also detect a weak (EW$=$$16pm10$ eV) and narrow (FWMH$<$5,500 km s$^{-1}$, consistent with optical H$alpha$) Fe K$alpha$ emission line at E$=$6.4 keV likely from the torus in the central regions of 3C 111, and we place an upper limit on the column density of a possible intrinsic warm absorber of $N_H$$<$$2.5times10^{20}$ cm$^{-2}$. These complexities make 3C 111 a very promising object for studying both the intrinsic properties of this active radio galaxy and the Galactic interstellar medium if used as a background source.
The energetic feedback that is generated by radio jets in active galactic nuclei (AGNs) has been suggested to be able to produce fast outflows of atomic hydrogen (HI) gas that can be studied in absorption at high spatial resolution. We have used the
Very Large Array (VLA) and a global very-long-baseline-interferometry (VLBI) array to locate and study in detail the HI outflow discovered with the Westerbork Synthesis Radio Telescope (WSRT) in the re-started radio galaxy 3C 236. We confirm, from the VLA data, the presence of a blue-shifted wing of the HI with a width of $sim1000mathrm{,km,s^{-1}}$. This HI outflow is partially recovered by the VLBI observation. In particular, we detect four clouds with masses of $0.28text{-}1.5times 10^4M_odot$ with VLBI that do not follow the regular rotation of most of the HI. Three of these clouds are located, in projection, against the nuclear region on scales of $lesssim 40mathrm{,pc}$, while the fourth is co-spatial to the south-east lobe at a projected distance of $sim270mathrm{,pc}$. Their velocities are between $150$ and $640mathrm{,km,s^{-1}}$ blue-shifted with respect to the velocity of the disk-related HI. These findings suggest that the outflow is at least partly formed by clouds, as predicted by some numerical simulations and originates already in the inner (few tens of pc) region of the radio galaxy. Our results indicate that all of the outflow could consist of many clouds with perhaps comparable properties as the ones detected, distributed also at larger radii from the nucleus where the lower brightness of the lobe does not allow us to detect them. However, we cannot rule out the presence of a diffuse component of the outflow. The fact that 3C 236 is a low excitation radio galaxy, makes it less likely that the optical AGN is able to produce strong radiative winds leaving the radio jet as the main driver for the HI outflow.
We present a Spitzer Infrared Spectrograph (IRS) map of H2 emission from the nearby galaxy NGC 4258 (Messier 106). The H2 emission comes from 9.4E6 Msun of warm molecular hydrogen heated to 240-1040 K in the inner anomalous arms, a signature of jet i
nteraction with the galaxy disk. The spectrum is that of a molecular hydrogen emission galaxy (MOHEG), with a large ratio of H2 over 7.7 micron PAH emission (0.37), characteristic of shocked molecular gas. We find close spatial correspondence between the H2 and CO emission from the anomalous arms. Our estimate of cold molecular gas mass based on CO emission is 10 times greater than our estimate of 1.0E8 Msun based on dust emission. We suggest that the X(CO) value is 10 times lower than the Milky Way value because of high kinetic temperature and enhanced turbulence. The H2 disk has been overrun and is being shocked by the jet cocoon, and much of the gas originally in the disk has been ejected into the galaxy halo in an X-ray-hot outflow. We measure a modest star formation rate of 0.08 Msun/yr in the central 3.4 square kpc that is consistent with the remaining gas surface density.
Recent analyses of the broad spectral energy distributions (SED) of extensive lobes of local radio-galaxies have confirmed the leptonic origin of their Fermi/LAT gamma-ray emission, significantly constraining the level of hadronic contribution. SED o
f distant (D > 125 Mpc) radio-galaxy lobes are currently limited to the radio and X-ray bands, hence give no information on the presence of non-thermal (NT) protons but are adequate to describe the properties of NT electrons. Modeling lobe radio and X-ray emission in 3C 98, Pictor A, DA 240, Cygnus A, 3C 326, and 3C 236, we fully determine the properties of intra-lobe NT electrons and estimate the level of the related gamma-ray emission from Compton scattering of the electrons off the superposed Cosmic Microwave Background, Extragalactic Background Light, and source-specific radiation fields.
We use statistical equilibrium equations to investigate the IRAC color space of shocked molecular hydrogen. The location of shocked H_2 in [3.6]-[4.5] vs [4.5]-[5.8] color is determined by the gas temperature and density of neutral atomic hydrogen. W
e find that high excitation H_2 emission falls in a unique location in the color-color diagram and can unambiguously be distinguished from stellar sources. In addition to searching for outflows, we show that the IRAC data can be used to map the thermal structure of the shocked gas. We analyze archival Spitzer data of Herbig-Haro object HH 54 and create a temperature map, which is consistent with spectroscopically determined temperatures.
سجل دخول لتتمكن من نشر تعليقات
التعليقات
جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
