G. Trinchieri, S. Pellegrini, G. Fabbiano, R. Fu, N. J. Brassington, A. Zezas, D. -W. Kim, J. Gallagher, L. Angelini, R. L. Davies, V. Kalogera, A. R. King, S. Zepf
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Accepted for publication in The Astrophysical Journal
We report the discovery of a faint (L_x ~ 4 10^37 erg/s, 0.5-2 keV), out-flowing gaseous hot interstellar medium (ISM) in NGC 3379. This represents the lowest X-ray luminosity ever measured from a hot phase of the ISM in a nearby early type galaxy. The discovery of the hot ISM in a very deep Chandra observation was possible thanks to its unique spectral and spatial signatures, which distinguish it from the integrated stellar X-ray emission, responsible for most of the unresolved emission in the Chandra data. This hot component is found in a region of about 800 pc in radius at the center of the galaxy and has a total mass M~ 3 10^5 solar masses. Independent theoretical prediction of the characteristics of an ISM in this galaxy, based on the intrinsic properti es of NGC 3379, reproduce well the observed luminosity, temperature, and radial distribution and mass of the hot gas, and indicate that the gas is in an outflowing phase, predicted by models but not observed in any system so far.
Motivated by the low-collisionality of gas accreted onto black holes in Sgr A* and other nearby galactic nuclei, we study a family of 2D advective accretion solutions with thermal conduction. While we only impose global inflow, the accretion flow spontaneously develops bipolar outflows. The role of conduction is key in providing the extra degree of freedom (latitudinal energy transport) necessary to launch these rotating thermal outflows. The sign of the Bernoulli constant does not discriminate between inflowing and outflowing regions. Our parameter survey covers mass outflow rates from ~ 0 to…
Observations and numerical magnetohydrodynamic (MHD) simulations indicate the existence of outflows and ordered large-scale magnetic fields in the inner region of hot accretion flows. In this paper we present the self-similar solutions for advection-dominated accretion flows (ADAFs) with outflows and ordered magnetic fields. Stimulated by numerical simulations, we assume that the magnetic field has a strong toroidal component and a vertical component in addition to a stochastic component. We obtain the self-similar solutions to the equations describing the magnetized ADAFs, taking into account…
Using the Submillimeter Array we report the discovery of a compact low mass bipolar molecular outflow from L1014-IRS and confirm its association with the L1014 dense core at 200 pc. Consequently, L1014-IRS is the lowest luminosity (L \~0.09 Lsun) and perhaps the lowest mass source known to be driving a bipolar molecular outflow, which is one of the smallest known in size (~500 AU), mass (< 10^{-4} Msun), and energetics (e.g., force < 10^{-7} Msun km/s/yr).
We present observations made with the Berkeley-Illinois-Maryland Association millimeter array of the H2S 2(2,0)-2(1,1) and C18O 2-1 transitions toward a sample of four hot molecular cores associated with ultracompact HII regions: G9.62+0.19, G10.47+0.03, G29.96-0.02 and G31.41+0.31. The angular resolution varies from 1.5 to 2.4 arcsec, corresponding to scales of ~0.06 pc at the distance of these sources. High-velocity wings characteristic of molecular outflows are detected toward all four sources in the H2S line. In two cases (G29.96 and G31.41) red- and blueshifted lobes are clearly defined a…
eta Carinae is a stellar binary system with a period of 5.54 years. It harbors one of the brightest and most massive stars in our galaxy. This paper presents spectroscopic evidence for a fast (up to 2,000 km/s) X-ray outflow of ionized gas launched from eta Carinae just before what is believed to be the binary periastron (point of smallest binary separation). The appearance of this high-velocity component, just as the irregular flares in the X-ray light curve, can not be explained by the simple continuous binary wind interaction, adding to the intrigue of the eta Carinae system.
We present self-similar solutions for advection -dominated accretion flows with thermal conduction in the presence of outflows. Possible effects of outflows on the accretion flow are parametrized and a saturated form of thermal conduction, as is appropriate for the weakly-collisional regime of interest, is included in our model. While the cooling effect of outflows is noticeable, thermal conduction provides an extra heating source. In comparison to accretion flows without winds, we show that the disc rotates faster and becomes cooler because of the angular momentum and energy flux which are ta…
Measurements of interstellar absorption lines in 18 ultraluminous infrared galaxies (ULIGs) have been combined with published data, in order to reassess the dependence of galactic outflow speeds on starburst luminosity and galactic mass. The Doppler shifts reveal outflows of relatively cool gas at $330 \pm 100$km/s. The outflow speeds increase with the star formation rate (SFR) as roughly $v \propto SFR^{0.35}$. This result is surprising since, in the traditional model for starburst-driven winds, these relatively cool gas clouds are accelerated by the ram pressure of a hot, supernova-heated wi…
We present the first fully sampled map of 12CO (1-0) emission from M82 covering the entire galaxy. Our map contains a 12 x 15 kpc^2 area. We find that extraplanar CO emission, previously reported at short distances above the galactic plane, extends to heights of up to 6 kpc above the disk. Some of this emission is associated with tidal arms seen in HI, implying either that M82 contained substantial amounts of molecular gas in the outer disk, or that molecular gas formed after the tidal features. CO emission along the direction of the outflow extends to distances of 3 kpc above and below the di…
We present a 5-37 micron infrared spectrum obtained with the Spitzer Space Telescope toward the southeastern lobe of the young protostellar outflow HH211. The spectrum shows an extraordinary sequence of OH emission lines arising in highly excited rotational levels up to an energy E/k~28200K above the ground level. This is, to our knowledge, by far the highest rotational excitation of OH observed outside Earth. The spectrum also contains several pure rotational transitions of H2O (v=0), H2 (v=0) S(0) to S(7), HD (v=0) R(3) to R(6), and atomic fine-structure lines of [Fe II], [Si II], [Ne II], […
The Eskimo Nebula (NGC 2392) is a double-shell planetary nebula (PN) known for the exceptionally large expansion velocity of its inner shell, ~90 km/s, and the existence of a fast bipolar outflow with a line-of-sight expansion velocity approaching 200 km/s. We have obtained XMM-Newton observations of the Eskimo and detected diffuse X-ray emission within its inner shell. The X-ray spectra suggest thin plasma emission with a temperature of ~2x10^6 K and an X-ray luminosity of L_X = (2.6+/-1.0)x10^31 (d/1150 pc)^2 ergs/s, where d is the distance in parsecs. The diffuse X-ray emission shows notice…
We present high sensitivity 12CO and 13CO (1-0) molecular line maps covering the full extent of the parsec scale Haro~6-10 Herbig-Haro (HH) flow. We report the discovery of a molecular CO outflow along the axis of parsec-scale HH flow. Previous molecular studies missed the identification of the outflow probably due to their smaller mapping area and the confusing spectral features present towards the object. Our detailed molecular line study of the full 1.6 pc extent of the optical flow shows evidence for both blueshifted and redshifted gas set in motion by Haro~6-10 activity. The molecular out…
The 24 M Jupiter mass brown dwarf 2MASS1207-3932 has for some time been known to show clear signs of classical T Tauri-like accretion. Through analysis of its oxygen forbidden emission we have discovered that it is driving a bipolar outflow. Blue and red-shifted components to the [OI] 6300 forbidden emission line are seen at velocities of - 8 km/s and +4 km/s. Spectro-astrometry recovers the position of both components relative to the BD, at ~ 0.08 arcseconds(in opposing directions). A position velocity diagram of the line region supports the spectro-astrometric results. The H-alpha and HeI 66…
This paper presents a large spectral line and continuum survey of 8 deeply embedded, low-mass protostellar cores using the Submillimeter Array. Each source was observed in high excitation lines of some of the most common molecular species, CO, HCO+, CS, SO, H2CO, CH3OH and SiO. Line emission from 11 species originating from warm and dense gas have been imaged at high angular resolution (1-3"; typically 200-600 AU) together with continuum emission at 230 GHz (1.3 mm) and 345 GHz (0.8 mm). Compact continuum emission is observed for all sources which likely originates in marginally optically thic…
We consider stationary, axisymmetric hydrodynamic accretion flows in Kerr geometry. As a plausible means of efficiently separating a small population of nonthermal particles from the bulk accretion flows, we investigate the formation of standing dissipative shocks, i.e. shocks at which fraction of the energy, angular momentum and mass fluxes do not participate in the shock transition of the flow that accretes onto the compact object but are lost into collimated (jets) or uncollimated (winds) outflows. The mass loss fraction (at a shock front) is found to vary over a wide range (0 - 95%) depend…
Spectroscopic observations of a solar limb flare recorded by SUMER on SOHO reveal, for the first time, hot fast magnetic reconnection outflows in the corona. As the reconnection site rises across the SUMER spectrometer slit, significant blue- and red-shift signatures are observed in sequence in the Fe XIX line, reflecting upflows and downflows of hot plasma jets, respectively. With the projection effect corrected, the measured outflow speed is between 900-3500 km/s, consistent with theoretical predictions of the Alfvenic outflows in magnetic reconnection region in solar impulsive events. Based…
We report the discovery of a massive SCUBA core with evidence of inflow and outflow motions. This core is detected by SCUBA at both 450 and 850 micro meter. Barely resolved by the telescope beam at 450 micro meter, it has a size of 10 arcsec, corresponding to 0.28 pc at a distance of 5.7 kpc. The dust temperature is estimated to be less than 29 K, the total mass is 820 solar mass and the average density is 1.1e-6 per cube-cm in a region with a radius of 5 arcsec. Follow-up spectral line observations, including HCN (3-2), HCO+ (3-2), H13CO+ (3-2) and C17O (2-1) reveal a typical blue profile whi…
We present a unified picture of outflowing gas from the X-ray binary system Hercules X-1/HZ Herculis. We suggest that the outflowing gas (a wind) causes UV emission seen in mid-eclipse, narrow UV absorption lines, and broad UV P Cygni lines. Observations with the FOS and STIS spectrographs on the Hubble Space Telescope (HST) show UV emission lines in the middle of X-ray eclipse, when the X-ray heated atmosphere of the normal star and accretion disk should be entirely hidden from view. Narrow absorption lines (FWHM~50 km/s) blueshifted by 500 km/s during observations in 1998 and by 400 km/s dur…
Motivated by relativistic jets observed in active galactic nuclei (AGN), we simulate outflows of electron-positron pairs strongly coupled with photons from normal electron-proton plasmas. Using multi-fluid approximation and a Monte Carlo method of radiative transfer, we obtain spherically symmetric, steady solutions of radiation and pair outflows for the luminosity $L \leq 10^{47}$ erg ${\rm s^{-1}}$. For microphysics, Coulomb scattering, Compton scattering, bremsstrahlung, electron-positron pair annihilation and creation are taken into account. Although a significant amount of pairs outflow b…
Spectroscopy of the infrared He I (10830A) line with KECK/NIRSPEC and IRTF/CSHELL, and of the ultraviolet C III (977A) and O VI (1032A) emission with FUSE reveals that the classical T Tauri star TW Hydrae exhibits P Cygni profiles, line asymmetries, and absorption indicative of a continuous, fast (~400 km/s), hot (~300,000 K) accelerating outflow with a mass loss rate \~10^-11 - 10^-12 solar masses per year, or larger. Spectra of T Tauri N appear consistent with such a wind. The source of the emission and outflow seems restricted to the stars themselves. Although the mass accretion rate is an …
A highly and rapidly variable bipolar mass outflow from StHa 190 has been discovered, the first time in a yellow symbiotic star. Permitted emission lines are flanked by symmetrical jet features and multi-component P-Cyg profiles, with velocities up to 300 km/sec. Given the high orbital inclination of the binary, if the jets leave the system nearly perpendicular to the orbital plane, the de-projected velocity equals or exceeds the escape velocity (1000 km/sec). StHa190 looks quite peculiar in many other respects: the hot component is an O-type sub-dwarf without an accretion disk or a veiling ne…
Numerical simulations suggest that active galactic nuclei (AGNs) play an important role in the formation of early-type galaxies by expelling gas and dust in powerful galactic winds and quenching star formation. However, the existence of AGN feedback capable of halting galaxy-wide star formation has yet to be observationally confirmed. To investigate this question, we have obtained spectra of 14 post-starburst galaxies at z~0.6 to search for evidence of galactic winds. In 10/14 galaxies we detect Mg II 2796,2803 absorption lines which are blueshifted by 490 - 2020 km/s with respect to the stars…
Aiming at a better understand of the physical and chemical processes in the hot molecular core stage of high-mass star formation, we observed the prototypical hot core G29.96-0.02 in the 862mu band with the Submillimeter Array (SMA) at sub-arcsecond spatial resolution. The observations resolved the hot molecular core into six submm continuum sources with the finest spatial resolution of 0.36''x0.25'' (~1800AU) achieved so far. Four of them located within 7800(AU)^2 comprise a proto-Trapezium system with estimated protostellar densities of 1.4x0^5 protostars/pc^3. The plethora of ~80 spectral l…
We present the discovery of several new regions of interaction between the ejecta and equatorial circumstellar ring of SN1987A, an interaction leading to a much expanded development of the supernova remnant. We also trace the development of the first such "hot spot," discovered in 1997, back to 1995. Later hot spots seem to have emerged by early 1999. We discuss mechanisms for the long delay between the first and later spots.
The radio lobes of Hydra A lie within cavities surrounded by a rim of enhanced X-ray emission in the intracluster gas. Although the bright rim appears cooler than the surrounding gas, existing Chandra data do not exclude the possibility that the rim is produced by a weak shock. A temperature map shows that cool gas extends out along the radio axis of Hydra A. The age of the radio source and equipartition pressure of the radio lobe argue against a shock, and comparison with similar structure in the Perseus Cluster also suggests that the rim is cool. We show that the cool bright rim cannot be th…
We present molecular line observations of the massive star forming region IRAS 17233-3606 aimed at studying the molecular core associated with the source. The observations were made using the Atacama Pathfinder Experiment telescope in the CO (3-2) and HCO^+ (4-3) transitions, and in the CH_3OH (6_K-5_K), (7_K-6_K) and CH_3CN (16_K-15_K) bands. For the CO(3-2) and HCO^+ (4-3) transitions, we obtained maps with a size of 70''\times 70''. The typical angular resolution of the data is ~18''. Our observations reveal an exceptionally rich molecular spectrum, a signpost of hot core activity. Comparis…
We report the results of spectroscopic mapping observations carried out toward a ~1 min x 1 min region within the northern lobe of the outflow from NGC 2071 using the Infrared Spectrograph (IRS) of the Spitzer Space Telescope. These observations covered the 5.2-37 um spectral region and have led to the detection of a number of ionic, atomic, and molecular lines, including fine-structure emission of Si+, Fe+, S++, S, the S(0)-S(7) pure rotational lines of H2, the R(3) and R(4) transitions of HD, and at least 11 transitions of H2O. In addition, the 6.2, 7.4, 7.6, 7.9, 8.6 and 11.3 um PAH emissio…
We detect a fast outflow of neutral and ionized gas with velocities up to about 1000 km/s from the central region of radio galaxy 3C 293. With optical spectroscopy we locate the bulk of the ionized gas outflow at the position of a bright radio hot-spot in the inner radio jet, about 1 kpc east of the nucleus. Given the presence of large amounts of cold gas and the distorted morphology of the radio jet in this region, we argue that the ISM is pushed out by a severe interaction with the radio plasma. The similarity of the outflow of HI with the ionized gas outflow that we see at the position of t…
We consider the X-ray emission due to bremsstrahlung processes from hot, low radiative-efficiency accretion flows around supermassive and galactic black holes. We calculate surface brightness profiles and Michelson visibility functions for a range of density profiles, rho ~ r^(-3/2+p), with 0 < p < 1, to allow for the presence of outflows. We find that although the 1 keV emitting region in these flows can always extend up to 10^6 Schwarzschild radii (R_S), their surface brightness profiles and visibility functions are strongly affected by the specific density profile. The advection-dominated s…
We investigate a scenario of photons scattering by electrons within a relativistic outflow. The outflow is composed of discrete shells with different speeds. One shell emits radiation for a short duration. Some of this radiation is scattered by the shell(s) behind. We calculate in a simple two-shell model the observed scattered flux density as a function of the observed primary flux density, the normalized arrival time delay between the two emission components, the Lorentz factor ratio of the two shells and the scattering shell's optical depth. Thomson scattering in a cold shell and inverse Co…
We show that the starburst-driven outflow in the peculiar galaxy NGC 2782 forms a well-defined collimated bubble which has an extent of $\sim$ 1 kpc and a closed shell at its edge, as seen in H$α$, [O III], and 5 GHz radio continuum. The shell coincides with the maximum in intensity and linewidths of [O III] lines in a blueshifted emission nebula which was previously detected via optical spectroscopy by Boer et al. (1992). Such a remarkable outflow morphology has not been observed to date in any other starburst galaxy of comparable luminosity. The radio continuum map reveals a second bubble of…
A survey of diffuse interstellar sight lines observed with the Far Ultraviolet Spectroscopic Explorer has led to the serendipitous discovery of a high-ionization nebula around the hot white dwarf KPD 0005+5106. The nebula has an OVI 1032A surface brightness of up to 25,000 photons/s/cm^2/sr, making it the brightest region of extended OVI emission in our survey. Photoionization models using the incident white dwarf continuum successfully reproduce the observed OVI intensity. The OVI emission arises in the highly ionized inner region of a planetary nebula around KPD 0005+5106. This newly discove…
We present initial results of a project to measure mean longitudinal magnetic fields in a group of sdB/OB/O stars. The project was inspired by the discovery of three super-metal-rich sdOB stars, each having metals (e.g. Ti, V) enhanced by factors of 10^3 to 10^5. Similar behaviour is observed in chemically peculiar A stars, where strong magnetic fields are responsible for the enrichment. With this in mind, we obtained circularly polarised spectra of two of the super-metal-rich sdOBs, two "normal" sdBs and two sdOs using FORS1 on the ESO/VLT. By examining circular polarisation in the hydrogen B…
We present polarisation measurements of sdB and sdO stars using FORS1 on the VLT. The observations were made as part of a project to determine whether magnetic fields in two super-metal-rich stars can explain their extreme abundance peculiarities. Field strengths of up to ~1.5 kG have been measured at varying levels of significance in each of our six targets, however no clear evidence was found between apparently normal subdwarfs and the metal-rich objects. The origin of the magnetic fields is unknown. We also discuss the implications of our measurements for magnetic flux conservation in late …
The discovery of collimated outflows associated to point-symmetric features in Planetary Nebulae has proliferated in recent years. The systematic variation of radial velocity that many of them show strongly suggests a uniform rotation or precession of the ejection direction. Although several physical processes have been invoked, the formation mechanism of precessing collimated outflows in PNe is currently an intriguing but unresolved problem.
We consider hot accretion disk outflows from black hole - neutron star mergers in the context of the nucleosynthesis they produce. We begin with a three dimensional numerical model of a black hole - neutron star merger and calculate the neutrino and antineutrino fluxes emitted from the resulting accretion disk. We then follow the element synthesis in material outflowing the disk along parameterized trajectories. We find that at least a weak r-process is produced, and in some cases a main r-process as well. The neutron-rich conditions required for this production of r-process nuclei stem direct…
