Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers
Abstract Ne viii absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas...
Gespeichert in:
| Veröffentlicht in: | Monthly notices of the Royal Astronomical Society 2017-04, Vol.466 (3), p.3133-3142 |
|---|---|
| Hauptverfasser: | , , , , |
| Format: | Artikel |
| Sprache: | eng |
| Schlagworte: | |
| Online-Zugang: | Volltext bestellen |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| container_end_page | 3142 |
|---|---|
| container_issue | 3 |
| container_start_page | 3133 |
| container_title | Monthly notices of the Royal Astronomical Society |
| container_volume | 466 |
| creator | Hussain, Tanvir Khaire, Vikram Srianand, Raghunathan Muzahid, Sowgat Pathak, Amit |
| description | Abstract
Ne viii absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas. Here, we study the implications of the recently updated UVB at low z to understand the ionization mechanisms of intervening Ne viii absorbers. With the updated UVB, one typically needs higher density and metallicity to reproduce the observed ionic column densities under photoionization. Both reduce the inferred line-of-sight thicknesses of the absorbers. We find a critical density of ≥5 × 10−5 cm−3 above which the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
can be reproduced by pure collisional processes. If the gas is of near solar metallicity (as measured for the low ions) then the cooling time-scales will be small ( |
| doi_str_mv | 10.1093/mnras/stw3265 |
| format | Article |
| fullrecord | <record><control><sourceid>proquest_TOX</sourceid><recordid>TN_cdi_proquest_miscellaneous_1884113140</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><oup_id>10.1093/mnras/stw3265</oup_id><sourcerecordid>4314255451</sourcerecordid><originalsourceid>FETCH-LOGICAL-c364t-7f4b5dbb633bb502dff9413441af302f9c5a739e4572f973bb0a0e40eb6ca6bd3</originalsourceid><addsrcrecordid>eNqN0T1PwzAQBmALgUQpjOyWWFhC7fgjyYgqPipVsMAc2YnduiR2sJ0imFj5m_wSQlsJiQWm00nPne70AnCK0QVGBZm01oswCfGFpJztgREmnCVpwfk-GCFEWJJnGB-CoxBWCCE6qBHws7ZrTCWicTZAp6GwsO9qEVUN-yZ6sTauURFKUT0tvOttDbXzMC4VHCbM22YQtqpaCmtCu1lhbFR-rayxC3inPt8_1sYYKGRwXiofjsGBFk1QJ7s6Bo_XVw_T22R-fzObXs6TinAak0xTyWopOSFSMpTWWhcUE0qx0ASluqiYyEihKMuGJhsQEkhRpCSvBJc1GYPz7d7Ou-dehVi2JlSqaYRVrg8lznOKMcEU_YNmWU5YltOBnv2iK9d7OzwyKJ6zFBOCB5VsVeVdCF7psvOmFf61xKj8DqvchFXuwvo5wPXdH_QLKPaaTQ</addsrcrecordid><sourcetype>Aggregation Database</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype><pqid>1868521331</pqid></control><display><type>article</type><title>Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers</title><source>Oxford Journals Open Access Collection</source><creator>Hussain, Tanvir ; Khaire, Vikram ; Srianand, Raghunathan ; Muzahid, Sowgat ; Pathak, Amit</creator><creatorcontrib>Hussain, Tanvir ; Khaire, Vikram ; Srianand, Raghunathan ; Muzahid, Sowgat ; Pathak, Amit</creatorcontrib><description>Abstract
Ne viii absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas. Here, we study the implications of the recently updated UVB at low z to understand the ionization mechanisms of intervening Ne viii absorbers. With the updated UVB, one typically needs higher density and metallicity to reproduce the observed ionic column densities under photoionization. Both reduce the inferred line-of-sight thicknesses of the absorbers. We find a critical density of ≥5 × 10−5 cm−3 above which the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
can be reproduced by pure collisional processes. If the gas is of near solar metallicity (as measured for the low ions) then the cooling time-scales will be small (<108 yrs). Therefore, a continuous injection of heat is required in order to enhance the detectability of the collisionally ionized gas. Using photoionization models we find that in almost all Ne viii systems the inferred low ion metallicity is near solar or supersolar. If we assume the Ne viii phase to have similar metallicities then photoionization can reproduce the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
without the line-of-sight thickness being unreasonably large and avoids cooling issues related to the collisional ionization at these metallicities. However, the indication of broad Lyα absorption in a couple of systems, if true, suggests that the Ne viii phase is distinct from the low ion phase having much lower metallicity.</description><identifier>ISSN: 0035-8711</identifier><identifier>EISSN: 1365-2966</identifier><identifier>DOI: 10.1093/mnras/stw3265</identifier><language>eng</language><publisher>London: Oxford University Press</publisher><subject>Absorption ; Astronomy ; Cooling ; Density ; Ionization ; Ions ; Line of sight ; Mathematical models ; Metallicity ; Photoionization ; Spectrum analysis ; Ultraviolet ; Ultraviolet radiation</subject><ispartof>Monthly notices of the Royal Astronomical Society, 2017-04, Vol.466 (3), p.3133-3142</ispartof><rights>2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society 2016</rights><rights>Copyright Oxford University Press, UK Apr 21, 2017</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c364t-7f4b5dbb633bb502dff9413441af302f9c5a739e4572f973bb0a0e40eb6ca6bd3</citedby><cites>FETCH-LOGICAL-c364t-7f4b5dbb633bb502dff9413441af302f9c5a739e4572f973bb0a0e40eb6ca6bd3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>314,777,781,1599,27905,27906</link.rule.ids><linktorsrc>$$Uhttps://dx.doi.org/10.1093/mnras/stw3265$$EView_record_in_Oxford_University_Press$$FView_record_in_$$GOxford_University_Press</linktorsrc></links><search><creatorcontrib>Hussain, Tanvir</creatorcontrib><creatorcontrib>Khaire, Vikram</creatorcontrib><creatorcontrib>Srianand, Raghunathan</creatorcontrib><creatorcontrib>Muzahid, Sowgat</creatorcontrib><creatorcontrib>Pathak, Amit</creatorcontrib><title>Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers</title><title>Monthly notices of the Royal Astronomical Society</title><description>Abstract
Ne viii absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas. Here, we study the implications of the recently updated UVB at low z to understand the ionization mechanisms of intervening Ne viii absorbers. With the updated UVB, one typically needs higher density and metallicity to reproduce the observed ionic column densities under photoionization. Both reduce the inferred line-of-sight thicknesses of the absorbers. We find a critical density of ≥5 × 10−5 cm−3 above which the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
can be reproduced by pure collisional processes. If the gas is of near solar metallicity (as measured for the low ions) then the cooling time-scales will be small (<108 yrs). Therefore, a continuous injection of heat is required in order to enhance the detectability of the collisionally ionized gas. Using photoionization models we find that in almost all Ne viii systems the inferred low ion metallicity is near solar or supersolar. If we assume the Ne viii phase to have similar metallicities then photoionization can reproduce the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
without the line-of-sight thickness being unreasonably large and avoids cooling issues related to the collisional ionization at these metallicities. However, the indication of broad Lyα absorption in a couple of systems, if true, suggests that the Ne viii phase is distinct from the low ion phase having much lower metallicity.</description><subject>Absorption</subject><subject>Astronomy</subject><subject>Cooling</subject><subject>Density</subject><subject>Ionization</subject><subject>Ions</subject><subject>Line of sight</subject><subject>Mathematical models</subject><subject>Metallicity</subject><subject>Photoionization</subject><subject>Spectrum analysis</subject><subject>Ultraviolet</subject><subject>Ultraviolet radiation</subject><issn>0035-8711</issn><issn>1365-2966</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2017</creationdate><recordtype>article</recordtype><recordid>eNqN0T1PwzAQBmALgUQpjOyWWFhC7fgjyYgqPipVsMAc2YnduiR2sJ0imFj5m_wSQlsJiQWm00nPne70AnCK0QVGBZm01oswCfGFpJztgREmnCVpwfk-GCFEWJJnGB-CoxBWCCE6qBHws7ZrTCWicTZAp6GwsO9qEVUN-yZ6sTauURFKUT0tvOttDbXzMC4VHCbM22YQtqpaCmtCu1lhbFR-rayxC3inPt8_1sYYKGRwXiofjsGBFk1QJ7s6Bo_XVw_T22R-fzObXs6TinAak0xTyWopOSFSMpTWWhcUE0qx0ASluqiYyEihKMuGJhsQEkhRpCSvBJc1GYPz7d7Ou-dehVi2JlSqaYRVrg8lznOKMcEU_YNmWU5YltOBnv2iK9d7OzwyKJ6zFBOCB5VsVeVdCF7psvOmFf61xKj8DqvchFXuwvo5wPXdH_QLKPaaTQ</recordid><startdate>20170421</startdate><enddate>20170421</enddate><creator>Hussain, Tanvir</creator><creator>Khaire, Vikram</creator><creator>Srianand, Raghunathan</creator><creator>Muzahid, Sowgat</creator><creator>Pathak, Amit</creator><general>Oxford University Press</general><scope>AAYXX</scope><scope>CITATION</scope><scope>8FD</scope><scope>H8D</scope><scope>L7M</scope><scope>7TG</scope><scope>KL.</scope></search><sort><creationdate>20170421</creationdate><title>Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers</title><author>Hussain, Tanvir ; Khaire, Vikram ; Srianand, Raghunathan ; Muzahid, Sowgat ; Pathak, Amit</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c364t-7f4b5dbb633bb502dff9413441af302f9c5a739e4572f973bb0a0e40eb6ca6bd3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2017</creationdate><topic>Absorption</topic><topic>Astronomy</topic><topic>Cooling</topic><topic>Density</topic><topic>Ionization</topic><topic>Ions</topic><topic>Line of sight</topic><topic>Mathematical models</topic><topic>Metallicity</topic><topic>Photoionization</topic><topic>Spectrum analysis</topic><topic>Ultraviolet</topic><topic>Ultraviolet radiation</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Hussain, Tanvir</creatorcontrib><creatorcontrib>Khaire, Vikram</creatorcontrib><creatorcontrib>Srianand, Raghunathan</creatorcontrib><creatorcontrib>Muzahid, Sowgat</creatorcontrib><creatorcontrib>Pathak, Amit</creatorcontrib><collection>CrossRef</collection><collection>Technology Research Database</collection><collection>Aerospace Database</collection><collection>Advanced Technologies Database with Aerospace</collection><collection>Meteorological & Geoastrophysical Abstracts</collection><collection>Meteorological & Geoastrophysical Abstracts - Academic</collection><jtitle>Monthly notices of the Royal Astronomical Society</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext_linktorsrc</fulltext></delivery><addata><au>Hussain, Tanvir</au><au>Khaire, Vikram</au><au>Srianand, Raghunathan</au><au>Muzahid, Sowgat</au><au>Pathak, Amit</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers</atitle><jtitle>Monthly notices of the Royal Astronomical Society</jtitle><date>2017-04-21</date><risdate>2017</risdate><volume>466</volume><issue>3</issue><spage>3133</spage><epage>3142</epage><pages>3133-3142</pages><issn>0035-8711</issn><eissn>1365-2966</eissn><abstract>Abstract
Ne viii absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas. Here, we study the implications of the recently updated UVB at low z to understand the ionization mechanisms of intervening Ne viii absorbers. With the updated UVB, one typically needs higher density and metallicity to reproduce the observed ionic column densities under photoionization. Both reduce the inferred line-of-sight thicknesses of the absorbers. We find a critical density of ≥5 × 10−5 cm−3 above which the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
can be reproduced by pure collisional processes. If the gas is of near solar metallicity (as measured for the low ions) then the cooling time-scales will be small (<108 yrs). Therefore, a continuous injection of heat is required in order to enhance the detectability of the collisionally ionized gas. Using photoionization models we find that in almost all Ne viii systems the inferred low ion metallicity is near solar or supersolar. If we assume the Ne viii phase to have similar metallicities then photoionization can reproduce the observed
$N({Ne \small{VIII}})/\rm N({O \small {VI}})$
without the line-of-sight thickness being unreasonably large and avoids cooling issues related to the collisional ionization at these metallicities. However, the indication of broad Lyα absorption in a couple of systems, if true, suggests that the Ne viii phase is distinct from the low ion phase having much lower metallicity.</abstract><cop>London</cop><pub>Oxford University Press</pub><doi>10.1093/mnras/stw3265</doi><tpages>10</tpages></addata></record> |
| fulltext | fulltext_linktorsrc |
| identifier | ISSN: 0035-8711 |
| ispartof | Monthly notices of the Royal Astronomical Society, 2017-04, Vol.466 (3), p.3133-3142 |
| issn | 0035-8711 1365-2966 |
| language | eng |
| recordid | cdi_proquest_miscellaneous_1884113140 |
| source | Oxford Journals Open Access Collection |
| subjects | Absorption Astronomy Cooling Density Ionization Ions Line of sight Mathematical models Metallicity Photoionization Spectrum analysis Ultraviolet Ultraviolet radiation |
| title | Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne viii absorbers |
| url | https://sfx.bib-bvb.de/sfx_tum?ctx_ver=Z39.88-2004&ctx_enc=info:ofi/enc:UTF-8&ctx_tim=2025-01-20T01%3A23%3A28IST&url_ver=Z39.88-2004&url_ctx_fmt=infofi/fmt:kev:mtx:ctx&rfr_id=info:sid/primo.exlibrisgroup.com:primo3-Article-proquest_TOX&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.genre=article&rft.atitle=Implications%20of%20an%20updated%20ultraviolet%20background%20for%20the%20ionization%20mechanisms%20of%20intervening%20Ne%E2%80%89viii%20absorbers&rft.jtitle=Monthly%20notices%20of%20the%20Royal%20Astronomical%20Society&rft.au=Hussain,%20Tanvir&rft.date=2017-04-21&rft.volume=466&rft.issue=3&rft.spage=3133&rft.epage=3142&rft.pages=3133-3142&rft.issn=0035-8711&rft.eissn=1365-2966&rft_id=info:doi/10.1093/mnras/stw3265&rft_dat=%3Cproquest_TOX%3E4314255451%3C/proquest_TOX%3E%3Curl%3E%3C/url%3E&disable_directlink=true&sfx.directlink=off&sfx.report_link=0&rft_id=info:oai/&rft_pqid=1868521331&rft_id=info:pmid/&rft_oup_id=10.1093/mnras/stw3265&rfr_iscdi=true |