Low Surface Brightness Hα Observations of Local Intergalactic Hydrogen Clouds

Donahue, M.; Aldering, Greg; Stocke, John T.

doi:10.1086/316771

Cited by 81 publications

(97 citation statements)

References 46 publications

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“…In fact, it contains two relatively unique features: (i) five individual HI tidal features extending from the disk (Rand & van der Hulst 1993;Rand 1994); and (ii) two HI supershells associated with massive star forming regions that are expelling large masses of gas at high velocities (Rand & van der Hulst 1993). Moreover, there is extensive diffuse Hα emission throughout the gas halo (Donahue et al 1995), spatially coincident with the gaseous streams. We compare these data to investigate any potential associations between the stellar and gaseous substructures.…”

Section: The Stellar Stream Of Ngc 4631mentioning

confidence: 99%

A Stellar Tidal Stream Around the Whale Galaxy, NGC 4631

Martínez–Delgado

D’Onghia²,

Chonis

et al. 2015

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We report the discovery of a giant stellar tidal stream in the halo of NGC 4631, a nearby edge-on spiral galaxy interacting with the spiral NGC 4656, in deep images taken with a 40 cm aperture robotic telescope. The stream has two components: a bridge-like feature extending between NGC 4631 and NGC 4656 (stream SE ) and an overdensity with extended features on the opposite side of the NGC 4631 disk (stream NW ). Together, these features extend more than 85 kpc in projection. The orientation of stream SE relative to the orientations of NGC 4631 and NGC 4656 is not consistent with an origin from an interaction between these two spirals, and is more likely debris from a satellite encounter. The stellar tidal features can be qualitatively reproduced in an N-body model of the tidal disruption of a single, massive dwarf satellite on a moderately eccentric orbit (e = 0.6) around NGC 4631 over ∼3.5 Gyr. Both modeling and inferences from the morphology of the streams indicate these are not associated with the complex HI tidal features observed between both spirals, which likely originate from a more recent, gas-rich accretion event. The structure of stream NW suggests that it may contain the progenitor of the stream, in agreement with the N-body model. However, we cannot exclude other possibilities such as the satellite dwarf galaxy NGC 4627 being the progenitor based on these data. In addition, stream NW is roughly aligned with two very faint dwarf spheroidal candidates. The system of dwarf galaxies and the tidal stream around NGC 4631 can provide an additional interesting case for exploring the anisotropy distribution of satellite galaxies recently reported around Local Group spiral galaxies by means of future follow-up observations.

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Section: The Stellar Stream Of Ngc 4631mentioning

confidence: 99%

A Stellar Tidal Stream Around the Whale Galaxy, NGC 4631

Martínez–Delgado

D’Onghia²,

Chonis

et al. 2015

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“…As the reported 16 kpc detection by Donahue et al (1995) still needs to be confirmed, we assume a |z|-extent of the DIG-halo of about 5.4 kpc (based on Martin & Kern (2001), but adjusted to the distance of D = 7.5 Mpc). Figure 6 presents first XMM-Newton contour images for all energy bands overlaid onto the Hα image of Golla et al (1996).…”

Section: Ngc 4631mentioning

confidence: 99%

The multi-phase gaseous halos of star forming late-type galaxies

Tüllmann

Pietsch²,

Rossa³

et al. 2006

A&A

152

175

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This study presents first results from an X-ray mini-survey carried out with XMM-Newton to investigate the diffuse Hot Ionized Medium in the halos of nine nearby star-forming edge-on spiral galaxies. Diffuse gaseous X-ray halos are detected in eight of our targets, covering a wide range of star formation rates from quiescent to starburst cases. For four edge-on spiral galaxies, namely NGC 3044, NGC 3221, NGC 4634, and NGC 5775, we present the first published high resolution/sensitivity detections of extended soft X-ray halos. EPIC X-ray contour maps overlaid onto Hα imaging data reveals that in all cases the presence of X-ray halos is correlated with extraplanar Diffuse Ionized Gas. Moreover, these halos are also associated with non-thermal cosmic ray halos, as evidenced by radio continuum observations. Supplemental UV-data obtained with the OM-telescope at 210 nm show Diffuse Ionized Gas to be well associated with UV emission originating in the underlying disk. Beside NGC 891, NGC 4634 is the second non-starburst galaxy with a diffuse soft X-ray halo (|z| ≤ 4 kpc). In case of NGC 3877, for which we also present the first high resolution X-ray imaging data, no halo emission is detectable. EPIC pn spectra (0.3-12 keV) of the diffuse X-ray emission are extracted at different offset positions from the disk, giving evidence to a significant decrease of gas temperatures, electron densities, and gas masses with increasing distance to the plane. A comparison between dynamical and radiative cooling time scales implies that the outflow in all targets is likely to be sustained. We find very strong indications that spatially correlated multi-phase gaseous halos are created by star forming activity in the disk plane. In a forthcoming paper, we will present multi-frequency luminosity relations and evaluate key parameters which might trigger the formation of multi-phase galaxy halos.

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“…DIG in NGC 891 and NGC 5775 has been detected to about kpc (Rand 1997;Hoopes et al 1999) and z = 5 z = 6 kpc (Collins et al 2000), respectively, while deep, wide-field imaging of NGC 4631 indicates emission up to 16 kpc from the plane (Donahue, Aldering, & Stocke 1995).…”

Section: Introductionmentioning

confidence: 99%

Ionization, Kinematics, and Extent of the Diffuse Ionized Gas Halo of NGC 5775

Rand

2000

The Astrophysical Journal

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We present key results from deep spectra of the diffuse ionized gas halo of the edge-on galaxy NGC 5775.[N ii] l6583 has been detected up to kpc above the plane in one of two vertically oriented long slits-making z ≈ 13 this the spiral galaxy with the greatest spectroscopically detected halo extent in emission. Key diagnostic line ratios have been measured up to kpc, allowing the source of ionization and physical state to be probed. z ≈ 8 Ionization by a dilute radiation field from massive stars in the disk can explain some of the line ratio behavior, but departures from this picture are clearly indicated, most strongly by the rise of [O iii]/Ha with z. Velocities of the gas in both slits approach the systemic velocity of the galaxy at several kiloparsecs above the plane. We interpret this trend as a decrease in rotation velocity with z, with essentially no rotation at heights of several kiloparsecs. Such a trend was observed in the edge-on galaxy NGC 891, but here much more dramatically. This falloff is presumably due to the gravitational potential changing with z, but will also depend on the hydrodynamic nature of the disk-halo cycling of gas and projection effects. More detailed modeling of the ionization and kinematics of this and other edge-ons will be presented in future papers.

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Low Surface Brightness Hα Observations of Local Intergalactic Hydrogen Clouds

Cited by 81 publications

References 46 publications

A Stellar Tidal Stream Around the Whale Galaxy, NGC 4631

A Stellar Tidal Stream Around the Whale Galaxy, NGC 4631

The multi-phase gaseous halos of star forming late-type galaxies

Ionization, Kinematics, and Extent of the Diffuse Ionized Gas Halo of NGC 5775

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