Calendar

Jul
3
Mon
Colloquium PhD Defense: Nigel Mathes
Jul 3 @ 2:00 pm – 3:00 pm
Colloquium PhD Defense: Nigel Mathes

The Vulture Survey of MgII and CIV Absorbers: Feasting on the Bones of Spectra Left to Die

Nigel Mathes, NMSU

Abstract:

We present detailed measurements of the absorption properties and redshift evolution of MgII and CIV absorbers as measured in archival spectra from the UVES spectrograph at the Very Large Telescope (VLT/UVES) and the HIRES spectrograph at the Keck Telescope (Keck/HIRES) to equivalent width detection limits below 0.01 angstroms. This survey examines 860 high resolution spectra from various archival data sets representing 700 unique sightlines, allowing for detections of intervening MgII absorbers spanning redshifts 0.1 < z < 2.6 and intervening CIV absorbers spanning redshifts 1 < z < 5. We employ an accurate, automated approach to line detection which consistently detects redshifted absorption doublets. We observe three distinct epochs of evolution in the circumgalactic medium (CGM) as traced by MgII and CIV absorbers. At high redshifts, from 3 < z < 5, galaxies rapidly build up a metal enriched halo where, despite significant evolution in the ionizing background, the production of metals through star formation driven outflows dominates observed trends increasing the number of observed absorbers per redshift path length towards z = 3. At mid redshifts, from 2 < z < 3, a large cosmic increase in the global star formation rate drives large numbers of high column density outflows into the halos of galaxies. At this time, metal line absorption of all species is increased above all other epochs. At low redshifts, for z < 2, the universe becomes more quiescent in both star formation and ionizing background. Weak, low column density MgII absorbers proliferate, while strong MgII absorbers likely fragment or re-accrete onto their host galaxy. Strong CIV absorbers, at this time, still increase in number per absorption path, while their weaker counterparts begin to disappear. MgII and CIV absorbers appear to originate in star formation driven outflows, but their different evolutionary properties imply they represent two physically distinct phases of gas. These two phases comprise the CGM and contribute separately to the cycle of baryons into and out of galaxies.

Aug
16
Thu
ASTR 620 – Planetary Processes
Aug 16 @ 8:55 am – 10:10 am
Aug
21
Tue
ASTR 620 – Planetary Processes
Aug 21 @ 8:55 am – 10:10 am
Aug
23
Thu
ASTR 620 – Planetary Processes
Aug 23 @ 8:55 am – 10:10 am
Aug
28
Tue
ASTR 620 – Planetary Processes
Aug 28 @ 8:55 am – 10:10 am
Aug
30
Thu
ASTR 620 – Planetary Processes
Aug 30 @ 8:55 am – 10:10 am
Sep
4
Tue
ASTR 620 – Planetary Processes
Sep 4 @ 8:55 am – 10:10 am
Sep
6
Thu
ASTR 620 – Planetary Processes
Sep 6 @ 8:55 am – 10:10 am
Sep
11
Tue
ASTR 620 – Planetary Processes
Sep 11 @ 8:55 am – 10:10 am
Sep
13
Thu
ASTR 620 – Planetary Processes
Sep 13 @ 8:55 am – 10:10 am