Tearing the Veil: Interaction of the Orion Nebula with its Neutral Environment

We present H I 21 cm observations of the Orion Nebula, obtained with the Karl G. Jansky Very Large Array, at an angular resolution of 7.''2 { imes} 5.''7 and a velocity resolution of 0.77 km s$^{-1}$. Our data reveal H I absorption in the Veil toward the radio continuum of the H II region, and H I emission arising from the Orion Bar photon-dominated region (PDR) and from the Orion-KL outflow. In the Orion Bar PDR, the H I signal peaks in the same layer as the H$_{2}$ near-infrared vibrational line emission, in agreement with models of the photodissociation of H$_{2}$. The gas temperature in this region is approximately 540 K, and the H I abundance in the interclump gas in the PDR is 5%-10% of the available hydrogen nuclei. Most of the gas in this region therefore remains molecular. Mechanical feedback on the Veil manifests itself through the interaction of ionized flow systems in the Orion Nebula, in particular the Herbig-Haro object HH 202, with the Veil. These interactions give rise to prominent blueward velocity shifts of the gas in the Veil. The unambiguous evidence for interaction of this flow system with the Veil shows that the distance between the Veil and the Trapezium stars needs to be revised downward to about 0.4 pc. The depth of the ionized cavity is about 0.7 pc, which is much smaller than the depth and the lateral extent of the Veil. Our results reaffirm the blister model for the M42 H II region, while also revealing its relation to the neutral environment on a larger scale.Interstellar matter and star formatio

A large-area near-infrared emission line survey for star forming galaxies at z=2.1-2.4

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

On measuring the Tully-Fisher relation at z > 1. A case study using strong Hα emitting galaxies at z > 1.5

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

The obscured circumnuclear region of the outflow galaxy NGC 3079

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Hα emitting galaxies and the cosmic star formation rate at z =~ 2.2

Wetensch. publicatieFaculteit der Wiskunde en Natuurwetenschappe

Herschel reveals a molecular outflow in a z = 2.3 ULIRG

We report the results from a 19-h integration with the Spectral and Photometric Imaging REceiver (SPIRE) Fourier Transform Spectrometer aboard the Herschel Space Observatory which has revealed the presence of a molecular outflow from the Cosmic Eyelash (SMM J2135−0102) via the detection of blueshifted OH absorption. Detections of several fine-structure emission lines indicate low-excitation H ii regions contribute strongly to the [C ii] luminosity in this z = 2.3 ultra-luminous infrared galaxy (ULIRG). The OH feature suggests a maximum wind velocity of 700 km s− 1, which is lower than the expected escape velocity of the host dark matter halo, ≈ 1000 km s− 1. A large fraction of the available molecular gas could thus be converted into stars via a burst protracted by the resulting gas fountain, until an active galactic nucleus (AGN)-driven outflow can eject the remaining gas

Herschel spectroscopic observations of the compact obscured nucleus in Zw 049.057

Context. The luminous infrared galaxy Zw 049.057 contains a compact obscured nucleus where a considerable amount of the galaxy's luminosity is generated. This nucleus contains a dusty environment that is rich in molecular gas. One approach to probing this kind of environment and to revealing what is hidden behind the dust is to study the rotational lines of molecules that couple well with the infrared radiation emitted by the dust. Aims. We probe the physical conditions in the core of Zw 049.057 and establish the nature of its nuclear power source (starburst or active galactic nucleus). Methods. We observed Zw 049.057 with the Photodetector Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) onboard the Herschel Space Observatory in rotational lines of H<inf>2</inf>O, H<inf>2</inf>¹⁸O, OH, ¹⁸OH, and [O I]. We modeled the unresolved core of the galaxy using a spherically symmetric radiative transfer code. To account for the different excitation requirements of the various molecular transitions, we use multiple components and different physical conditions. Results. We present the full high-resolution SPIRE FTS spectrum of Zw 049.057, along with relevant spectral scans in the PACS range. We find that a minimum of two different components (nuclear and extended) are required in order to account for the rich molecular line spectrum of Zw 049.057. The nuclear component has a radius of 10-30 pc, a very high infrared surface brightness (∼10¹⁴L<inf>⊙</inf>kpc^-2), warm dust (T<inf>d</inf> > 100 K), and a very large H<inf>2</inf> column density (N<inf>H</inf><inf>2</inf> = 10²⁴-10²⁵ cm^-2). The modeling also indicates high nuclear H<inf>2</inf>O (∼5 × 10^-6) and OH (∼4 × 10^-6) abundances relative to H<inf>2</inf> as well as a low ¹⁶O/¹⁸O-ratio of 50-100. We also find a prominent infall signature in the [O I] line. We tentatively detect a 500 km s^-1 outflow in the H<inf>2</inf>O 3<inf>13</inf> → 2<inf>02</inf> line. Conclusions. The high surface brightness of the core indicates the presence of either a buried active galactic nucleus or a very dense nuclear starburst. The estimated column density towards the core of Zw 049.057 indicates that it is Compton-thick, making a buried X-ray source difficult to detect even in hard X-rays. We discuss the elevated H<inf>2</inf>O abundance in the nucleus in the context of warm grain and gas-phase chemistry. The H<inf>2</inf>O abundance is comparable to that of other compact (ultra-)luminous infrared galaxies such as NGC 4418 and Arp 220 - and also to hot cores in the Milky Way. The enhancement of ¹⁸O is a possible indicator that the nucleus of Zw 049.057 is in a similar evolutionary stage as the nuclei of Arp 220 - and more advanced than NGC 4418. We discuss the origin of the extreme nuclear gas concentration and note that the infalling gas detected in [O I] implies that the gas reservoir in the central region of Zw 049.057 is being replenished. If confirmed, the H<inf>2</inf>O outflow suggests that the nucleus is in a stage of rapid evolution

High-J CO versus Far-infrared Relations in Normal and Starburst Galaxies

Galaxie

Red quasars blow out molecular gas from galaxies during the peak of cosmic star formation

Galaxie