We present 3-D modelling of the distribution and kinematics of the neutral
hydrogen in the spiral galaxy ESO 123-G23. The optical appearance of this
galaxy is an almost perfectly edge-on disk, while the neutral hydrogen is found
to extend vertically out to about 15 kpc on either side of the galactic plane.
The HI layer and the major features of the HI data cube can be successfully
explained by a model dominated by a strong (about 30 degrees) line-of-sight
warp. Other models were tried, including a flare model and a two-component
model, but they clearly do not reproduce the data. This is the first
unambiguous detection of a galactic warp that has the maximum deviation from
the central plane almost along the line-of-sight. No evidence for the presence
of any companion galaxy is found in the HI data cube. Line-of-sight warps in
edge-on galaxies are probably frequent, but escape detection as they are too
weak. Moreover they may easily be mistaken as flares or 'thick disks'. A 3-D
modelling of the HI layer as the one presented here is needed in order to
distinguish between these possibilities.Comment: 5 pages, 5 figures, accepted by A&

Becquaert

Bottema

Briggs

F. Fraternali

Fraternali

G. Gentile

García-Ruiz

Karachentsev

Ostriker

P. Salucci

Persic

Reshetnikov

Rogstad

Schwarz

Sofue

Swaters

Toomre

U. Klein

Verheijen

Warmels

English

arXiv

We present 3-D modelling of the distribution and kinematics of
the neutral hydrogen in the spiral galaxy ESO 123-G23. The optical appearance 
of this galaxy is an almost perfectly edge-on disk, while the neutral hydrogen is found
to extend vertically out to about 15 kpc on either side of the galactic plane. 
The H I layer and the major features of the H I data cube
can be successfully explained by a model dominated by a strong
(about 30°) line-of-sight warp. Other 
models were tried, including a flare model and a two-component model, but they clearly 
do not reproduce the data. 
This is the 
first unambiguous detection of a galactic warp that has the maximum deviation from the 
central plane almost along the line-of-sight.
No evidence for the presence of any 
companion galaxy is found in the H I data cube. 
Line-of-sight warps in edge-on galaxies are probably 
frequent, but escape detection as they are too weak. Moreover they may 
easily be mistaken as flares or “thick disks”. A 3-D modelling of the H I 
layer as the one presented here is needed in order to distinguish between 
these possibilities.

EDP Sciences OAI-PMH repository (1.2.0)

The line-of-sight warp of the spiral galaxy ESO 123-G23

Gentile, G

Fraternali, F

Klein, U

Salucci, P

University of Groningen

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 12-11-2019aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universita¨t Bonn, Auf demHu¨gel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the rst unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) { Galaxies: kinematics and dynamics { Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garca-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as \unfavourable", as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Dierent models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum dierent from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsgure !g1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1  1020 cm−2 (pseudo-3σdened similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ...  1020 cm−2. The HI beam is shown in thetop left corner. radopt1

University of Groningen Research Database

  
 University of Groningen
The line-of-sight warp of the spiral galaxy ESO 123-G23
Gentile, G; Fraternali, Filippo; Klein, U; Salucci, P
Published in:
Astronomy & astrophysics
DOI:
10.1051/0004-6361:20030733
IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from
it. Please check the document version below.
Document Version
Publisher's PDF, also known as Version of record
Publication date:
2003
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO
123-G23. Astronomy & astrophysics, 405(3), 969-973. DOI: 10.1051/0004-6361:20030733
Copyright
Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the
author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).
Take-down policy
If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately
and investigate your claim.
Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the
number of authors shown on this cover page is limited to 10 maximum.
Download date: 10-02-2018
aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23
G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4
G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universita¨t Bonn, Auf dem
Hu¨gel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands Kapteyn
Astronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,
Trieste, Italy Received / Accepted
We present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxy
ESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutral
hydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HI
layer and the major features of the HI data cube can be successfully explained by a model dominated by a
strong (about 30) line-of-sight warp. Other models were tried, including a flare model and a two-component
model, but they clearly do not reproduce the data. This is the rst unambiguous detection of a galactic
warp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence for
the presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxies
are probably frequent, but escape detection as they are too weak. Moreover they may easily be mistaken
as flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order to
distinguish between these possibilities.
Galaxies: individual (ESO 123-G23) { Galaxies: kinematics and dynamics { Galaxies: structure Intro-
duction
The outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garca-Ruiz et al.
garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to much
larger radii than the optical disk. HI warps obey some general rules, one of them being that they usually
start around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observed
HI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of the
various possible orientations that warps can have, one is considered as \unfavourable", as the warp becomes
less visible: this is when the largest deviation from the central plane occurs along the line-of-sight.
The origin of warps is still poorly understood. Dierent models have been proposed, for instance: the
precession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),
or the accretion of gas with angular momentum dierent from that of the disk (e.g. Ostriker & Binney
ostriker), but none is completely satisfactory.
In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culled
from the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-
lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-
minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurements
tracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−
G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithers
of−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthec
of − sight.Theotherpossibilitiesareclearlyruledout.
Observations
gure !g1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observed
data cube (top) and of the line-of-sight warp model (bottom). Contours are 1  1020 cm−2 (pseudo-3σ
dened similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ...  1020 cm−2. The HI beam is shown in the
top left corner. radopt
1


We present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxy ESO 123- G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutral hydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HI layer and the major features of the HI data cube can be successfully explained by a model dominated by a strong ( about 30') line-of-sight warp. Other models were tried, including a flare model and a two-component model, but they clearly do not reproduce the data. This is the first unambiguous detection of a galactic warp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence for the presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxies are probably frequent, but escape detection as they are too weak. Moreover they may easily be mistaken as flares or "thick disks". A 3-D modelling of the HI layer as the one presented here is needed in order to distinguish between these possibilities.</p

Proceedings - University of Groningen

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 03-06-2022aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universität Bonn, Auf demHügel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30◦) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the first unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) – Galaxies: kinematics and dynamics – Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garćıa-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as “unfavourable”, as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Different models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum different from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsfigure !fig1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1 × 1020 cm−2 (pseudo-3σdefined similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ... × 1020 cm−2. The HI beam is shown in thetop left corner. radopt1

Dissertations of the University of Groningen

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 16-07-2023aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universität Bonn, Auf demHügel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30◦) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the first unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) – Galaxies: kinematics and dynamics – Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garćıa-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as “unfavourable”, as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Different models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum different from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsfigure !fig1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1 × 1020 cm−2 (pseudo-3σdefined similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ... × 1020 cm−2. The HI beam is shown in thetop left corner. radopt1

ARTS repository - University of Groningen

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 04-12-2023aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universität Bonn, Auf demHügel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30◦) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the first unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) – Galaxies: kinematics and dynamics – Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garćıa-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as “unfavourable”, as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Different models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum different from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsfigure !fig1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1 × 1020 cm−2 (pseudo-3σdefined similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ... × 1020 cm−2. The HI beam is shown in thetop left corner. radopt1

Salucci, Paolo

SISSA Digital Library

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 04-06-2022aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universität Bonn, Auf demHügel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30◦) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the first unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) – Galaxies: kinematics and dynamics – Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garćıa-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as “unfavourable”, as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Different models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum different from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsfigure !fig1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1 × 1020 cm−2 (pseudo-3σdefined similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ... × 1020 cm−2. The HI beam is shown in thetop left corner. radopt1

   University of GroningenThe line-of-sight warp of the spiral galaxy ESO 123-G23Gentile, G; Fraternali, F; Klein, U; Salucci, PPublished in:Astronomy & astrophysicsDOI:10.1051/0004-6361:20030733IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite fromit. Please check the document version below.Document VersionPublisher's PDF, also known as Version of recordPublication date:2003Link to publication in University of Groningen/UMCG research databaseCitation for published version (APA):Gentile, G., Fraternali, F., Klein, U., & Salucci, P. (2003). The line-of-sight warp of the spiral galaxy ESO123-G23. Astronomy & astrophysics, 405(3), 969-973. https://doi.org/10.1051/0004-6361:20030733CopyrightOther than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of theauthor(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons).The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license.More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne-amendment.Take-down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediatelyand investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons thenumber of authors shown on this cover page is limited to 10 maximum.Download date: 26-04-2023aa graphicx txfonts document The line-of-sight warp of the spiral galaxy ESO 123-G23G. Gentile 1 F. Fraternali 2,3 U. Klein 1 P. Salucci 4G. Gentile, ggentile@astro.uni-bonn.de Radioastronomisches Institut der Universität Bonn, Auf demHügel 71, 53121, Bonn, Germany ASTRON, P.O. Box 2, 7990 AA Dwingeloo, The Netherlands KapteynAstronomical Institute, Postbus 800, 9700 AV, Groningen, The Netherlands SISSA, via Beirut 4, 34013,Trieste, Italy Received / AcceptedWe present 3-D modelling of the distribution and kinematics of the neutral hydrogen in the spiral galaxyESO 123-G23. The optical appearance of this galaxy is an almost perfectly edge-on disk, while the neutralhydrogen is found to extend vertically out to about 15 kpc on either side of the galactic plane. The HIlayer and the major features of the HI data cube can be successfully explained by a model dominated by astrong (about 30◦) line-of-sight warp. Other models were tried, including a flare model and a two-componentmodel, but they clearly do not reproduce the data. This is the first unambiguous detection of a galacticwarp that has the maximum deviation from the central plane almost along the line-of-sight. No evidence forthe presence of any companion galaxy is found in the HI data cube. Line-of-sight warps in edge-on galaxiesare probably frequent, but escape detection as they are too weak. Moreover they may easily be mistakenas flares or ’thick disks’. A 3-D modelling of the HI layer as the one presented here is needed in order todistinguish between these possibilities.Galaxies: individual (ESO 123-G23) – Galaxies: kinematics and dynamics – Galaxies: structure Intro-ductionThe outer parts of the disks of spiral galaxies are frequently warped (Bosma bosma, Garćıa-Ruiz et al.garcia-ruiz). Warps are best seen with HI observations, since the neutral hydrogen extends out to muchlarger radii than the optical disk. HI warps obey some general rules, one of them being that they usuallystart around R25 (Briggs briggs). The measured angle between the inner plane and the outermost observedHI ring spans a wide range of values, from a few degrees to a few tens in some exceptional cases. Of thevarious possible orientations that warps can have, one is considered as “unfavourable”, as the warp becomesless visible: this is when the largest deviation from the central plane occurs along the line-of-sight.The origin of warps is still poorly understood. Different models have been proposed, for instance: theprecession of a disk embedded in a flattened dark halo, misaligned with the disk itself (e.g. Toomre toomre),or the accretion of gas with angular momentum different from that of the disk (e.g. Ostriker & Binneyostriker), but none is completely satisfactory.In an ongoing project to study the dark matter distribution of spiral galaxies a sample was culledfrom the list of Persic and Salucci (persic) selecting the best determined optical rotation curves; the se-lection criteria were: symmetry of the Hα rotation curve, high angular extent, high HI flux and low lu-minosity (Gentile et al., in prep.) The aim was to combine these optical data with HI measurementstracing the gravitational potentials much further out. One of these galaxies, the edge-on spiral ESO 123−G23, turnedouttolookremarkableinitsHIdistribution.IndeedtheHIemissionextendsfaraway(uptoabout15kpc)fromeithersof−sight.WehavethereforemodelledtheHIlayerofESO123−G23consideringthesepossibilities.Ouranalysisshowsthatthecof − sight.Theotherpossibilitiesareclearlyruledout.Observationsfigure !fig1.eps Optical DSS image (grey scale) overlayed with the HI total intensity map of the observeddata cube (top) and of the line-of-sight warp model (bottom). Contours are 1 × 1020 cm−2 (pseudo-3σdefined similarly to Verheijen & Sancisi verheijen), 4, 7, 10, ... × 1020 cm−2. The HI beam is shown in thetop left corner. radopt1

The line-of-sight warp of the spiral galaxy ESO 123-G23

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