1. Hydrogen emission from the ionized gaseous halos
of low redshift galaxies
Huanian Zhang, Dennis Zaritsky
The University of Arizona
September 16, 2016
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 1 / 5
2. Geometry
Observer
A
B
C
r1
r2
r3
r4
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 2 / 5
redshift of prime galaxy:
0.05 < z < 0.2.
3. Results
6400 6500 6600 6700
λ [ ˚A]
−4
−2
0
2
4
6
f[10−20
ergcm−2
s−1˚A
−1
]
prime
6400 6500 6600 6700
λ [ ˚A]
random
6400 6500 6600 6700
λ [ ˚A]
random
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 3 / 5
4. Results
¯s = a(rp/50 kpc)b + c, with ∆f = ¯s − c
10−2
10−1
100
rp [Mpc]
10−5
10−4
10−3
10−2
10−1∆f[10−17
ergcm−2
s−1˚A
−1
] Previous limit
Mean
Median
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 4 / 5
5. Discussion
In 50 < rp < 100 kpc, 3σ detection of Hα + [NII],
(1.87 ± 0.6) × 10−20 erg cm−2 s−1 arcsec−2.
Density profile (Werk J. K. et al., 2014, ApJ, 792, 8)
nH = 10−4.2
(rp/Rvir)−0.8
Recombination coefficient (cm3s−1) (Pequignot D., Petitjean P.,
Boisson C., 1991, A&A, 251, 680)
αeff
Hα = 10−13 2.274 T−0.659
1 + 1.939 T0.574
, T = 104
K
Gas temperature can be infered: 12,000 K.
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 5 / 5
6. homogeneity
Homogeneity: 10 < log L/L ≤ 11 and 2 < r50 ≤ 10 kpc.
Over 7.2 million lines of sight used for a sample of 491,469 galaxies.
10.0 10.5 11.0
log(L/L⊙)
102
103
104
105
Numberofgalaxies
0 2 4 6 8 10 12
r50 [kpc]
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 1 / 0
7. Results
3500 4500 5500 6500 7500
λ [ ˚A]
−1.0
−0.5
0.0
0.5
1.0
f[10−17
ergcm−2
s−1˚A
−1
]
[O II]
H9
Ca II
H δ
G Hβ
[O III]
Mg b Na I
Hα+
[N II]
[S II]
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 2 / 0
8. Residual spectra
6300 6400 6500 6600 6700 6800
λ [ ˚A]
−1.0
−0.5
0.0
0.5
1.0
f[10−17
ergcm−2
s−1˚A
−1
]
Huanian Zhang, Dennis Zaritsky (The Universities of Arizona)Hydrogen emission from the ionized gaseous halos of low redshift galaxiesSeptember 16, 2016 3 / 0
